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Changes in Particle Size Composition under Seepage Conditions of Reclaimed Soil in Xinjiang, China Zizhao Zhang 1,2 , Wanghua Sui 1, * , Kaikai Wang 2 , Guobin Tang 2 and Xiaoping Li 2 1 2

*

School of Resources and Geosciences, China University of Mining and Technology, Xuzhou 221116, China; [email protected] School of Geological and Mining Engineering, Xinjiang University, Urumqi 830046, China; [email protected] (K.W.); [email protected] (G.T.); [email protected] (X.L.) Correspondence: [email protected]; Tel.: +86-139-5219-9519; Fax: +86-516-8359-0998

Received: 15 September 2018; Accepted: 17 October 2018; Published: 20 October 2018

Abstract: The distribution of reclaimed soil particle size under seepage conditions after the management period will directly determine the success or failure of reclamation work. The geotechnical experimental method was used in this paper to study the changes in the granulometric composition of soil. The results show that the granulometric composition of the reclaimed soil varied obviously at different depths. The granulometric composition of the soil at a depth of 10 cm was not much different from undisturbed reclaimed soil (URS). At a depth of 30 cm, as the sharp decrease of the content of fine particles resulted in coarser reclaimed soil, the soil became more uniform, with an increase in porosity and water content. At a depth of 50 cm, the fine particle content was generally slightly lower than that of URS. At a depth of 70 cm, the fine particle content of the soil greatly exceeded that of the URS, with the finest soil particles and lowest porosity. The main reason for the above-mentioned changes of granulometric composition in the reclaimed soil was the seepage in soil caused by irrigation during the management period. The research results can provide a reference for management after land reclamation at non-metallic mines in Xinjiang, China. Keywords: Xinjiang; land reclamation; management period; soil particle size; fluid flow in reclaimed soil

1. Introduction There are vast non-metallic mineral resources in the northern foothills of the Tianshan Mountains in Xinjiang, and the large-scale exploitation of mineral resources is bound to cause irreversible damage to the fragile geological environment and ecological environment in this region. Non-metallic mines in this region include limestone, dolomite, and granite mines. The open-pit mining method is mainly adopted. Large and deep open pits, and a large number of massive hard waste rocks (Figures 1 and 2), will be formed after mining. For mines whose damaged lands are grassland and woodland, the land will be reclaimed after the pits are closed. To reclaim the land, the waste rock is backfilled into the open pits first, and then the surface of the land is covered with soil and vegetation is planted. In order to ensure the survival rate of the vegetation, a one-year management period is set. The quality of the reclaimed soil after the management period will directly determine the success or failure of the reclamation work [1], and the distribution of soil particle size will directly affect the soil fertility, texture, and water holding capacity [2].

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Figure 1.1.Open-pit mining area. Figure1. Open-pit mining Figure Open-pit miningarea. area.

Figure2. 2. Waste Waste rock Figure rockpiles. piles. Figure 2. Waste rock piles.

In recent years, research [3–17] on the physical properties of reclaimed soils has achieved great In recent recent years, years, research [3–17] [3–17] on on the the physical physical properties of of reclaimed reclaimed soils soils has has achieved achieved great In success. Research research on the granulometric composition properties of reclaimed soil mainly included the followinggreat success. Research on the granulometric composition of reclaimed soil mainly included the following following success. Research the granulometric composition of reclaimed soil mainly includedsoil the aspects: Using on multifractal theory to analyze the granulometric composition of reclaimed [18–20], aspects: Using multifractal multifractal theory to analyze analyze the soils granulometric composition ofmethods reclaimed soil [18– [18– granulometric composition analysis of reclaimed under different reclamation [21–24], aspects: Using theory to the granulometric composition of reclaimed soil 20], granulometric granulometric composition analysis ofsoil reclaimed soils under different reclamation methods [21– granulometric composition ofanalysis reclaimed before and after reclamation inreclamation different years [25–27], [21– 20], composition of reclaimed soils under different methods 24], granulometric granulometric composition of reclaimed reclaimed soil before before and after after composition reclamationofin inreclaimed differentsoil years [25– and using spectrum analytical methods to analyze the granulometric [28]. [25– 24], composition of soil and reclamation different years 27], and using spectrum analytical methods to analyze the granulometric composition of reclaimed The previous research mainly focused on the granulometric composition of reclaimed soil in coal 27], and using spectrum analytical methods to analyze the granulometric composition of reclaimed mining areas, with clay soil or loam soil focused as the main reclaimed soil.composition Different test methods were soil soil [28]. [28]. The previous research mainly ontype the of granulometric of reclaimed reclaimed soil The previous research mainly focused on the granulometric composition of soil used to study the granulometric composition of reclaimed soil under different reclamation modes or test in coal mining areas, with clay soil or loam soil as the main type of reclaimed soil. Different in coal mining areas, with clay soil or loam soil as the main type of reclaimed soil. Different test in different has been research directed at sandy loam, into account the effect of methods wereyears. usedThere to study study theless granulometric composition of taking reclaimed soil under under different methods were used to the granulometric composition of reclaimed soil different the irrigation water the management period, to study changes directed in the particle size ofloam, the soil reclamation modes or during in different different years. There There has been been lessthe research at sandy sandy taking reclamation modes or years. has less research directed at loam, taking at different depths orinwith different overlaying soil thickness under different compaction circumstance. into account account the the effect effect of of the the irrigation irrigation water water during during the the management management period, period, to to study study the the changes changes in in into In view of the limitations of the past studies and the importance of soil particle size to reclamation the particle size of the soil at different depths or with different overlaying soil thickness under the particle size of takes the soil at different different overlaying soil thickness under work, this study the typical sandydepths loam at or thewith non-metallic mines in the northern foothills of different compaction circumstance. the Tianshan Mountains in Xinjiang as a research object. An in-situ test method was used for the first different compaction circumstance. In view view of the thethe limitations ofeffect the of past studies and and the importance importance ofsoils. soil Furthermore, particle size size to to time to simulate compaction reclamation machinery on reclaimedof In of limitations of the past studies the soil particle reclamation work,indoor this study study takes the the typical sandy sandy loam at at the the statistical non-metallic mines inapplied the northern northern field sampling, geotechnical experiments, and mathematical analysis werein to reclamation work, this takes typical loam non-metallic mines the foothills of the Tianshan Mountains in Xinjiang as a research object. An in-situ test method was used studyofthe in the granulometric composition of the reclaimed soil in-situ under seepage conditions foothills thechanges Tianshan Mountains in Xinjiang as a research object. An test method was used afterfirst a one-year period. for the time tomanagement simulate the compaction effect of reclamation machinery on reclaimed soils.

for the first time to simulate the compaction effect of reclamation machinery on reclaimed soils. Furthermore, field field sampling, sampling, indoor indoor geotechnical geotechnical experiments, experiments, and and mathematical mathematical statistical statistical analysis analysis Furthermore, were applied to study the changes in the granulometric composition of the reclaimed soil under were applied to study the changes in the granulometric composition of the reclaimed soil under seepage conditions conditions after after aa one-year one-year management management period. period. seepage

2. Materials Materials and and Methods Methods 2. The reclaimed reclaimed soil soil in-situ in-situ test test was was conducted conducted at at the the Changji Changji Groundwater Groundwater Balance Balance Experiment Experiment The Site in Xinjiang. The reclaimed soil was taken from a limestone ore mine in Dabancheng, which


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Materialsto and Methods soil and 2. belonged sandy loam, with a bulk unit weight of 12.646 kN/m3, a porosity of 57.71%, and The reclaimed soilThe in-situ test was at the Changji Balance Experiment a water content of 11.76%. lower partconducted of the reclaimed soilGroundwater was backfilled with the waste rock Site in Xinjiang. The reclaimed soil was taken from a limestone ore mine in Dabancheng, which belongs produced by the limestone mining. to the northern foothills of the Tianshan Mountains in Xinjiang. The soil was calcic brown soil and A total of 6 test barrels were used in this test (Figures 3–6). The depth of the test barrels was 2 belonged to sandy loam, with a bulk unit weight of 12.646 kN/m3 , a porosity of 57.71%, and a water m. The test wasofdivided intolower 2 groups. In one group, was backfilled content 11.76%. The part of the reclaimed soilthe wasbarrel backfilled with the waste by rockoverlaying produced bysoil with a thickness of 30 cm,mining. 50 cm, and 70 cm without compaction, while in the other group, the overlying the limestone A total ofonce 6 testby barrels were usedbulldozer. in this test (Figures 3–6). part The depth the test barrels 2 m. soil was compacted a track-type The lower of theofreclaimed soilwas was backfilled The test was divided into 2 groups. In one group, the barrel was backfilled by overlaying soil with a of the with limestone waste rocks. The plate load test (Figure 7) was used to simulate the compaction thickness of 30 cm, 50 cm, and 70 cm without compaction, while in the other group, the overlying soil bulldozer based on the intensity of pressure of the bulldozer on the ground, which was different from was compacted once by a track-type bulldozer. The lower part of the reclaimed soil was backfilled previouswith conventional drop weight tests. In the management period, watering was conducted in limestone waste rocks. The plate load test (Figure 7) was used to simulate the compaction of accordance with thebased empirical of of thepressure irrigation and theground, number of times of irrigation in the bulldozer on thevalue intensity of thevolume bulldozer on the which was different previous conventional drop weight tests. of In the the land from reclamation and management period themanagement mine areaperiod, in thewatering foothillswas ofconducted XinjianginTianshan accordance with the empirical value of the volume irrigationwas volume and the of times of in Mountains (Figures 8 and 9). The irrigation related tonumber the thickness of irrigation the soil layer. The the land reclamation and management period of the mine area in the foothills of Xinjiang Tianshan thicker the soil layer was, the greater the irrigation volume would be. Irrigation was carried out a Mountains (Figures 8 and 9). The irrigation volume was related to the thickness of the soil layer. total of three times in the period of management. After one year of management, samples were taken The thicker the soil layer was, the greater the irrigation volume would be. Irrigation was carried out a at depthstotal of of 10three cm, times 30 cm, 50 period cm, and 70 cm depending the ofsamples the overlaying in the of management. After oneon year of thickness management, were takensoil, and at depths of 10sample cm, 30 cm, 50 400 cm, and 70 cmsamples depending on the thickness the overlaying soil, and for the particle the weight of each was g. The were then takenof into the laboratory weight of each sample was 400 g. The samples were then taken into the laboratory for particle size size analysis. Sieving analysis was adopted as the soil has a high content of sand and low content of analysis. Sieving analysis was adopted as the soil has a high content of sand and low content of clay clay (Figure 10). At the same time, the undisturbed soil samples were taken at the corresponding (Figure 10). At the same time, the undisturbed soil samples were taken at the corresponding depth for depth forlaboratory laboratory tests of its density and water content. tests of its density and water content.

Figure 3. Empty cylindrical test barrels.

Figure 3. Empty cylindrical test barrels.

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Figure 4. Backfilled waste rock in lower part of test barrels. Figure 4. Backfilled waste rock in lower part of test barrels. Figure Backfilledwaste waste rock rock in test barrels. Figure 4. 4. Backfilled in lower lowerpart partofof test barrels.

Figure 5. Uncompacted reclaimed soil test barrel. Figure 5. Uncompacted reclaimed soil test barrel. Figure 5. Uncompacted reclaimed soil test barrel. Figure 5. Uncompacted reclaimed soil test barrel.

Figure 6. Reclaimed soil after one-compaction test barrel.

Figure 6. Reclaimed soil after one-compaction test barrel. Figure 6. Reclaimed soil after one-compaction test barrel. Figure 6. Reclaimed soil after one-compaction test barrel.

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Figure 7. Illustration of the setup for plate load test. Figure 7. Illustration of the setup for plate load test. Figure 7. Illustration of the setup for plate load test.

Figure 7. Illustration of the setup for plate load test.

Figure 8. Uncompacted reclaimed soil test barrel after irrigation. Figure 8. Uncompacted reclaimed soil test barrel after irrigation. Figure 8. Uncompacted reclaimed soil test barrel after irrigation. Figure 8. Uncompacted reclaimed soil test barrel after irrigation.

Figure 9. One-compactionreclaimed reclaimed soil after irrigation. Figure 9. One-compaction soiltest testbarrel barrel after irrigation. Figure 9. One-compaction reclaimed soil test barrel after irrigation.

Figure 9. One-compaction reclaimed soil test barrel after irrigation.


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Figure 10.Sieving Sieving method. Figure 10. method.

3. Results and Discussions

3. Results and Discussions 3.1. Experimental Data Processing

3.1. Experimental Data Processing A total of 18 soil samples were obtained after a one-year management period for particle size analysis. This sampling can be conducted at the depth of the interface between the reclaimed soil and

A total ofrock, 18 soil samples a one-year management forsoil particle size waste mainly because were varyingobtained degrees ofafter subsidence (Figure 8) occurred in theperiod overlaying of analysis. the This sampling conducted at the depth the interface the reclaimed reclaimed soil can due be to surface irrigation during the of one-year period ofbetween management, and some ofsoil and the mainly soil particles could varying enter the lower partof of subsidence the waste rock. In order8)tooccurred ensure thein accuracy of the waste rock, because degrees (Figure the overlaying soil physical properties of soil (density, porosity, water content), another three samples were taken from of the reclaimed soil due to surface irrigation during the one-year period of management, and some each depth. Table 1 lists the experimental results. of the soil particles could enter the lower part of the waste rock. In order to ensure the accuracy of the physical properties of soil (density, porosity, water content), another three samples were taken from each depth. Table 1 lists the experimental results.


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Table 1. Results of the reclaimed soil particle size analysis after a one-year management period. Percentage (%) of Soil with Particle Size Less than dx (mm) by Mass

Characteristic Particle Size (mm)

Test Barrel No.

Sampling Depth (cm)

≤10.0

≤5.0

≤2.0

≤1.0

≤0.5

≤0.25

≤0.1

≤0.075

d10

d30

d50

d60

A1 A1 A2 A2 B1 B1 B1 B2 B2 B2 C1 C1 C1 C1 C2 C2 C2 C2 URS

10 30 10 30 10 30 50 10 30 50 10 30 50 70 10 30 50 70 -

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100

100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 90.97

93.54 94.19 91.41 94.35 95.76 98.96 98.56 97.01 97.35 89.35 96.10 97.83 98.83 98.70 97.02 96.29 97.90 98.49 87.56

91.11 90.44 83.26 81.15 92.33 93.16 96.11 91.06 93.50 82.90 88.75 92.30 92.98 96.73 95.19 89.74 94.52 96.84 81.83

70.53 71.38 74.58 66.22 73.95 71.91 71.68 69.66 61.90 61.75 57.90 45.20 64.63 80.08 79.14 67.84 68.34 80.16 63.70

40.08 13.96 43.68 26.32 36.60 15.41 37.58 42.71 23.40 35.10 31.95 7.67 26.43 60.18 39.46 25.66 30.24 60.23 39.58

4.43 2.42 6.33 0.85 2.65 4.61 3.83 7.41 3.45 2.15 2.47 0.67 1.68 18.7 6.33 5.73 3.71 21.8 5.45

0.8 0.28 1.03 0.32 0.30 1.13 0.53 0.98 0.87 0.35 0.45 0.32 0.28 8.50 0.95 0.50 0.88 6.67 0.70

0.12 0.23 0.11 0.16 0.13 0.21 0.13 0.11 0.15 0.13 0.14 0.27 0.15 0.08 0.12 0.14 0.14 0.08 0.12

0.20 0.32 0.18 0.28 0.22 0.31 0.22 0.19 0.29 0.22 0.24 0.40 0.28 0.14 0.20 0.28 0.25 0.09 0.19

0.32 0.39 0.29 0.38 0.33 0.39 0.33 0.30 0.41 0.37 0.41 0.54 0.39 0.20 0.31 0.38 0.37 0.19 0.34

0.39 0.43 0.36 0.45 0.39 0.43 0.38 0.39 0.49 0.48 0.53 0.62 0.46 0.26 0.36 0.44 0.43 0.26 0.45

Cu

n

θ (%)

3.20 1.92 3.13 2.85 2.90 2.09 2.88 3.48 3.15 3.58 3.88 2.25 3.04 3.23 3.11 3.24 3.13 3.20 3.77

0.542 0.520 0.489 0.503 0.536 0.523 0.510 0.504 0.520 0.513 0.530 0.525 0.511 0.472 0.515 0.520 0.504 0.492 0.577

13.70 23.28 13.60 23.23 13.93 23.73 21.52 14.00 23.81 16.07 14.09 24.01 23.51 20.93 13.85 24.19 22.28 22.44 13.58

Note: Test barrel A represents overlaying soil thickness of 30 cm, B represents overlaying soil thickness of 50 cm, and C represents overlaying soil thickness of 70 cm; 1 represents uncompacted, and 2 represents compacted; A1 represents that the overlaying soil thickness is 10 cm and is uncompacted. d10 is the effective particle. d50 is the average particle size. Cu = d60 /d10 is the non-uniform coefficient of the soil; Cu ≥ 5 indicates non-homogeneous soils, and Cu < 5 indicates homogeneous soils. URS represents a sample of undisturbed reclaimed soil. n represents porosity. θ represents volumetric water content.


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3.2. Granulometric Composition Analysis of Reclaimed Soil after the Management Period 3.2.1. Analysis of the Factors Affecting the Changes in Granulometric Composition of Reclaimed Soil after the Management Period According to the Kalkiski soil classification system for soil particle sizes [29], 0.25 mm was used as the classification standard to distinguish between fine sand and medium sand; in the international standard for soil particle size classification, 0.2 mm is used as the classification standard to distinguish between coarse sand and fine sand, while in soil science and soil mechanics, 0.1 mm is taken as the classification standard to distinguish between fine and coarse particles. In order to reflect the change in the granulometric composition of reclaimed soil after the one-year management period, 0.25 mm, 0.1 mm, and d50 were studied as the focus of analysis. For the data on the granulometric composition of the reclaimed soil after the one-year management period (Table 1), variance analysis was done with the use of the multivariate in the general linear model in IBM SPSS Statistics (IBM, Chicago, IL, US); the percentage of particles with a size of ≤0.25 mm, ≤0.1 mm, and d50 were used as the dependent variables, and soil thickness and sampling depth as fixed factors. Table 2 lists the results of variance analysis. The results show that soil thickness has an insignificant effect on particle distribution (p > 0.05), and sampling depth has a significant effect on particle distribution (p < 0.05). The overlying soil of non-metallic mines in the northern foothills of the Tianshan Mountains in Xinjiang is mainly composed of sandy soil with a large amount of sand. In order to reflect the changes in the grain size of reclaimed soils at different depths, especially the changes of the fine particles, the percentage of soil particles with a size of ≤0.25 mm was used in the comparison of particle sizes at different depths. Table 3 lists the comparative analysis results. The results show that the fine particle content at the depth of 70 cm is significantly different from those at other depths (p < 0.05), and there is also a significant difference between the fine particle content at the depth of 10 cm and that at the depth of 30 cm (p = 0.039). The difference between the fine particle content at the depth of 70 cm and the depth at 30 cm is the most significant (p = 0.002). Table 2. Test results of the inter-subject effect after variance analysis. Source

Dependent Variables

III-Type Sum of Square

df

Mean Square

F

Sig.

Correction Model

≤0.25 mm ≤0.1 mm d50

2179.926 a 506.317 b 0.066 c

5 5 5

435.985 101.263 0.013

3.987 25.118 3.352

0.023 0.000 0.040

Intercept

≤0.25 mm ≤0.1 mm d50

17,383.524 713.252 1.161

1 1 1

17,383.524 713.252 1.161

158.963 176.922 293.865

0.000 0.000 0.000

Soil Thickness

≤0.25 mm ≤0.1 mm d50

12.190 2.179 0.005

2 2 2

6.095 1.090 0.003

0.056 0.270 0.677

0.946 0.768 0.527

Sampling Depth

≤0.25 mm ≤0.1 mm d50

2017.396 440.730 0.065

3 3 3

672.465 146.910 0.022

6.149 36.441 5.492

0.009 0.000 0.013

Note: a R square = 0.624 (adjusted R square = 0.468); b R square = 0.913 (adjusted R square = 0.876); c R square = 0.583 (adjusted R square = 0.409). Sig. = significance, the values are the statistical p value, if p < 0.05, the difference is significant.


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Table 3. Results of multiple comparative analyses. Dependent Variables

(I) Sampling Depth (cm)

(J) Sampling Depth (cm)

Difference in the Means (I−J) a

Standard Deviation

Sig.

95% Confidence Interval Lower Limit

Upper Limit

10

30 50 70

14.0100 12.0758 −20.7917 a

6.03754 6.75017 8.53837

0.039 0.099 0.031

0.8553 −2.6315 −39.3952

27.1647 26.7832 −2.1882

30

10 50 70

−14.0100 a −1.9342 −34.8017 a

6.03754 6.75017 8.53837

0.039 0.779 0.002

−27.1647 −16.6415 −53.4052

−0.8553 12.7732 −16.1982

50

10 30 70

−12.0758 1.9342 −32.8675 a

6.75017 6.75017 9.05631

0.099 0.779 0.003

−26.7832 −12.7732 −52.5995

2.6315 16.6415 −13.1355

70

10 30 50

20.7917 a 34.8017 a 32.8675 a

8.53837 8.53837 9.05631

0.031 0.002 0.003

2.1882 16.1982 13.1355

39.3952 53.4052 52.5995

≤0.25 mm

Note: a The difference of means is significant at 0.05 level; Sig. = significance.

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3.2.2. Analysis of the Granulometric Composition of Reclaimed Soil after the Management Period 3.2.2. Analysis the Granulometric Composition of Reclaimed Soil after the Management Period under Differentof Overlaying Soil Thickness under Different Overlaying Soil Thickness The data of Table 1 is plotted into the gradation cumulative curve of the soil particles, where the The data of Table 1 is plotted into the gradation cumulative curve of the soil particles, where abscissa is the particle size (mm), and the ordinate is the mass (cumulative percentage) content of the the abscissa is the particle size (mm), and the ordinate is the mass (cumulative percentage) content soil which is smaller than a certain particle size. The figure shows the relative content of each particle of the soil which is smaller than a certain particle size. The figure shows the relative content of each group in the soil, and it is the basis for calculating d10, d30, and other characteristic values. The particle group in the soil, and it is the basis for calculating d10 , d30 , and other characteristic values. uniformity or the gradation of the soil can be roughly judged according to the slope of the curve. A The uniformity or the gradation of the soil can be roughly judged according to the slope of the curve. steep curve indicates that the soil particles are relatively uniform, and the quality of corresponding A steep curve indicates that the soil particles are relatively uniform, and the quality of corresponding granular group is relatively centralized. The situation is the opposite when the curve is gentle. granular group is relatively centralized. The situation is the opposite when the curve is gentle. The accumulative curve of the soil particle gradation with an overlaying soil thickness of 30 cm The accumulative curve of the soil particle gradation with an overlaying soil thickness of 30 cm is shown in Figure 11. It shows that when the overlaying soil thickness is 30 cm, regardless of if it is is shown in Figure 11. It shows that when the overlaying soil thickness is 30 cm, regardless of if it is compacted or not, the fine-grained soil content at the sampling depth of 30 cm is significantly smaller compacted or not, the fine-grained soil content at the sampling depth of 30 cm is significantly smaller than that of the undisturbed reclaimed soil (URS). This is because this depth is the interface between than that of the undisturbed reclaimed soil (URS). This is because this depth is the interface between soil and waste rock. The 30 cm overlaying soil is thin and the water would seep into the soil during soil and waste rock. The 30 cm overlaying soil is thin and the water would seep into the soil during irrigation, and the seepage process can easily carry the fine particles of the soil down to the pores in irrigation, and the seepage process can easily carry the fine particles of the soil down to the pores in the large waste rocks. Fine particle content of the uncompacted reclaimed soil is even smaller than the large waste rocks. Fine particle content of the uncompacted reclaimed soil is even smaller than the compacted reclaimed soil at the depth of 30 cm. This is because the surface soil is compacted, the the compacted reclaimed soil at the depth of 30 cm. This is because the surface soil is compacted, the water seepage is slow, and less fine particles would be carried down to the waste rock layer compared water seepage is slow, and less fine particles would be carried down to the waste rock layer compared with the uncompacted reclaimed soil. In the actual irrigation process, it can also be found that the with the uncompacted reclaimed soil. In the actual irrigation process, it can also be found that the uncompacted reclaimed soil would display a higher settlement in the process of irrigation compared uncompacted reclaimed soil would display a higher settlement in the process of irrigation compared with the compacted one (Figures 8 and 9). At the depth of 10 cm, the content of fine particles of with the compacted one (Figures 8 and 9). At the depth of 10 cm, the content of fine particles of compacted soil are slightly higher than that of the URS and uncompacted soil, which is mainly compacted soil are slightly higher than that of the URS and uncompacted soil, which is mainly because because the compaction results in an increase in the content of fine particles [20,23]. the compaction results in an increase in the content of fine particles [20,23].

Figure 11. Accumulative curvecurve of particle gradation of soilof with soil thickness of 30 cmof(A1 and A2). Figure 11. Accumulative of particle gradation soiloverlaying with overlaying soil thickness 30 cm (A1 and A2).

The accumulative curve of the soil particle gradation with an overlaying soil thickness of 50 cm is shown in Figure 12. curve Whenof the soil is 50 cm with thick,anthe irrigationsoil volume is larger The accumulative theoverlaying soil particle gradation overlaying thickness of 50than cm that of the 30 cm overlaying soil, and when the thickness of the soil overlayer increases, the seepage is shown in Figure 12. When the overlaying soil is 50 cm thick, the irrigation volume is larger than timeofinthe the30soil be longer. Thewhen results that the finesoil particle content is significantly less that cmwould overlaying soil, and theshow thickness of the overlayer increases, the seepage than that of the URS at the depth of 30 cm. Furthermore, the fine particle content in the uncompacted time in the soil would be longer. The results show that the fine particle content is significantly less reclaimed much less. Thisofis30 also result of thethe seepage in the content soil; thatinis, the water seeps than that ofsoil the is URS at the depth cm.the Furthermore, fine particle the uncompacted downward after irrigation, and the seepage is fast in uncompacted soil with a large downward seepage reclaimed soil is much less. This is also the result of the seepage in the soil; that is, the water seeps force, resulting in a large loss of fine particles at the depth of 30 cm. At the depth of 50 cm, which downward after irrigation, and the seepage is fast in uncompacted soil with a large downwardis the junction ofresulting soil and waste rock,loss theof fine particle content close to of the URS. This of is 50 mainly seepage force, in a large fine particles at theisdepth of that 30 cm. At the depth cm, because the soil layer is thick and the seepage is slow at this depth, with a smaller seepage force, and which is the junction of soil and waste rock, the fine particle content is close to that of the URS. This thus the loss of fine is insignificant. is mainly because theparticles soil layer is thick and the seepage is slow at this depth, with a smaller seepage

force, and thus the loss of fine particles is insignificant.


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Figure 12. Accumulative curve of particle gradation of soil with overlaying soil thickness of 50 cm (B1 and B2). Figure 12. Accumulative curve of particle gradation of soil withwith overlaying soil soil thickness of 50ofcm and B2). Figure 12. Accumulative curve of particle gradation of soil overlaying thickness 50 (B1 cm (B1 and TheB2). accumulative curve of the soil particle gradation with an overlaying soil thickness of 70 cm

The accumulative curve of the soil particle gradation with an overlaying soil thickness of 70 cm is shown shown in in Figure Figure 13. 13. The overlaying soil irrigation volume further is The thickness thickness of of the the overlaying soil and and the the irrigation volume are are further The accumulative curve of the soil particle gradation with an overlaying soil thickness of 70 cm increased. The greatest change compared with overlaying soil thicknesses of 30 cm and 50 cm is that that increased. The greatest change compared with overlaying soil thicknesses of 30 cm and 50 cm is is shown in Figure 13. The thickness of depth the overlaying soil junction and the of irrigation volume are further the fine particles sharply increase at the of 70 cm (the soil and waste rock). This is the fine particles sharply increase at the depth of 70 cm (the junction of soil and waste rock). This is increased. The greatest change compared with overlaying soil thicknesses of 30 cm and 50 cm is that because, as as the the soil soil layer layer becomes becomes thicker, the fine fine particle particle content content of of the the soil soil would would increase, increase, and and the the because, thicker, the the fine particles sharply increase at the depth of The 70 cm (the junctionare offormed soil andinto waste rock). This is downward seepage of the soil would get slower. finer particles sedimentation at downward seepage of the soil would get slower. The finer particles are formed into sedimentation at because, as the soil layer becomes thicker, the fine particle content of the soil would increase, and the the depth of 70 cm, resulting in a sharp increase in the fine particles. the depth of 70 cm, resulting in a sharp increase in the fine particles. downward seepage of the soil would get slower. The finer particles are formed into sedimentation at the depth of 70 cm, resulting in a sharp increase in the fine particles.

Figure 13. Accumulative curvecurve of particle gradation of soil overlaying soil thickness of 70ofcm Figure 13. Accumulative of particle gradation ofwith soil with overlaying soil thickness 70(C1 cm and (C1 C2). and C2). of Change in Granulometric Composition of Reclaimed Soil at Different Depths after 3.2.3.Figure Analysis 13. Accumulative curve of particle gradation of soil with overlaying soil thickness of 70 cm (C1 the Management Period and C2). 3.2.3. Analysis of Change in Granulometric Composition of Reclaimed Soil at Different Depths after

Figures 14–16Period show that after the one-year management period the content of fine particles at the the Management 3.2.3. Analysis of Change in Granulometric of Reclaimed Soilcontent at Different Depths afterof depth of 10 cm is not significantly differentComposition from that of the URS, and the of fine particles Figures 14–16 show that after the one-year management period the content of fine particles at the Management Period compacted reclaimed soil is slightly higher than that of the URS. This is because the surface compaction the depth of increase 10 cm is in not significantly different fromAt that the URS, the of particles results in an content particles. theof depth of 30and cm, the content content of fine fine particles Figures 14–16 showthe that after of thefine one-year management period the content of fine particles at of compacted reclaimed soil is slightly higher than that of the URS. This is because the surface is lower than that of the URS, and the lowest value arises in the test barrel of uncompacted overlaying the depth of 10 cm is not significantly different from that of the URS, and the content of fine particles compaction results inofan70increase in the by content of fine particles. At the depth of 30 cm, thesoil content soil with a thickness cm,isfollowed the test barrels of the uncompacted overlaying with of compacted reclaimed soil slightly higher than that of the URS. This is because the surface of fine particles is lower than that of the URS, and the lowest value arises in the test barrel of thicknesses of 50 cminand 30 cm. Atinthe depth of 50 cm, the fine particle is slightly lower than compaction results an increase the content of of fine70 particles. At thecontent depth of 30 cm, the content uncompacted overlaying soil with a thickness cm, followed by the test barrels of the that of the URS, while at the depth cm,URS, the fine content is much of the of fine particles is lower than thatofof70the andparticle the lowest value ariseshigher in thethan testthat barrel of uncompacted overlaying soilabove-mentioned with thicknesses phenomenon of 50 cm andis30the cm. At the depth ofthe 50management cm, the fine URS. The main reason for the irrigation during uncompacted overlaying soil with a thickness of 70 cm, followed by the test barrels of the particle content is slightly lowervaries than that the URS,overlaying while at thesoil depth of 70 cm, the fine particle period. The irrigation withofdifferent thicker the uncompacted overlayingvolume soil with thicknesses of 50 cm and 30 cm. Atthicknesses. the depth of The 50 cm, the fine particle content is slightly lower than that of the URS, while at the depth of 70 cm, the fine particle


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content is much higher than that of the URS. The main reason for the above-mentioned phenomenon content is much higher than of the URS. The mainThe reason for the above-mentioned phenomenon is the irrigation during thethat management period. irrigation volume varies with different Processes 2018, 6, 201 12 of 18 is the irrigation during the period. The irrigation volume varies volume with different overlaying soil thicknesses. Themanagement thicker the overlaying soil is, the greater the irrigation would overlaying soil thicknesses. The thicker the overlaying is, the volume would be. After irrigation, the water starts to flow downwardsoil along the greater pores ofthe theirrigation reclaimed soil from the be. After irrigation, the water starts to flow downward along the pores of the reclaimed soil from the surface. Thesoil seepage is fast uncompacted soil and slow in compacted soil. from overlaying is, thespeed greater the in irrigation volume would be. After irrigation, theTherefore, water starts to surface. Thetoseepage speed isof fast inreclaimed uncompacted soil and in compacted soil. Therefore, the surface the along deeper part theof soil, the speed gradually slows down, the flow downward the pores the reclaimed soilseepage fromslow the surface. The seepage speedand isfrom fast the surface to thebecomes deeper of the reclaimed soil, the seepage speed slows down, the seepage volume smaller. The seepage speed on the surface of the reclaimed soil isand large, in uncompacted soil andpart slow in compacted soil. Therefore, from gradually the surface to the deeper part seepage volume becomes smaller. The seepage speed on the surface of the reclaimed soil is large, with seepage volume and large downward seepage and it could carry the coarse becomes and fine of thegreat reclaimed soil, the seepage speed gradually slowsforce, down, and the seepage volume with great andthe large downward seepage it could carry the and fine particles inseepage the soil volume downward, causing the of force, the entire surface of theseepage soilcoarse and making it smaller. The seepage speed on surface of subsidence the reclaimed soil is and large, with great volume and particles in the soil downward, causing the subsidence of the entire surface of the soil and making it dense. Therefore,seepage the content ofand the itfine-grained at the depth of particles 10 cm does notsoil change much large downward force, could carry soil the coarse and fine in the downward, dense. Therefore, the content of the fine-grained soil at the depth of 10 cm does not change much compared with the fine particle content of the of URS. the depth of 30 itcm, the seepage speed causing the subsidence of the entire surface theAt soil and making dense. Therefore, thebecomes content compared with the fine particle content of the URS. At the depth of 30 cm, the seepage speed becomes slower and could only carry fine-grained soil into the pores of deep soil; the uncompacted reclaimed of the fine-grained soil at the depth of 10 cm does not change much compared with the fine particle slower could only fine-grained soil into the pores of deep soil; the reclaimed soil wasand and thecarry porosity is 30 large, causing the fine-grained soil to uncompacted move and content ofloose the URS. At the depth of cm, the seepage speed becomes slower and downward, could only carry soil was in loose and the porosity is large, causing the fine-grained soil and resulting asoil great loss fine-grained soil. the At the overlaying soil thickness of move 70loose cm,downward, the fine-grained into theofpores of deep soil; uncompacted reclaimed soil to was andfine-grained the porosity resulting in a great loss of fine-grained soil. At the overlaying soil thickness of 70 cm, the fine-grained soil content deceases the most greatly because the irrigation volume reaches maximum. At a is large, causing the fine-grained soil to move downward, and resulting in a greatthe loss of fine-grained soil deceases the greatly because irrigation volume reaches the maximum. At a depth 50 overlaying cm, the seepage speed further slows down, thus thesoil fine particle content is only soil. content Atofthe soilmost thickness of 70 cm, thethe fine-grained content deceases the mostslightly greatly depth of the 50 the seepage speed slows down, thus the fine isspeed only slightly reduced. At cm, the depth of 70 cm, thefurther seepage velocity isAt the most ofseepage the fine particles are because irrigation volume reaches the maximum. a slowest, depth of and 50particle cm, thecontent further reduced. At the depth of 70 cm, the seepage velocity is the slowest, and most of the fine particles are gathered here.thus the fine particle content is only slightly reduced. At the depth of 70 cm, the seepage slows down, gathered velocity ishere. the slowest, and most of the fine particles are gathered here.

Figure 14. Accumulative curve of particle gradation of soil at the sampling depth of 10 cm. Figure 14. 14. Accumulative Accumulative curve curve of of particle particle gradation gradation of of soil soil at at the the sampling sampling depth depth of of 10 10 cm. cm. Figure

Figure 15. Accumulative curve of particle gradation of soil at the sampling depth of 30 cm. Figure 15. Accumulative curve of particle gradation of soil at the sampling depth of 30 cm. Figure 15. Accumulative curve of particle gradation of soil at the sampling depth of 30 cm.


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Figure and 7070 cm. Figure 16. 16. Accumulative Accumulative curve curve of ofparticle particlegradation gradationofofsoil soilatatthe thesampling samplingdepths depthsofof5050cm cm and 3.2.4.cm. Effects of Changes in Granulometric Composition of Reclaimed Soil to Physical Properties after

the Management Period 3.2.4. Effects of Changes in Granulometric Composition of Reclaimed Soil to Physical Properties correlation afterThe the bivariate Management Periodanalysis method in SPSS was used to analyze the correlation between the variation of soil particle size (especially the change of fine particles) and the physical properties, such The bivariate correlation analysis method in SPSS was soil. usedTable to analyze the degree correlation between as porosity, water content, and soil homogeneity of reclaimed 4 lists the of correlation the variation of soil particle size (especially the change of fine particles) and the physical properties, between the percentage coposition of soil with a particle size less than or equal to 0.25 mm or 0.1 mm, as porosity, water content, and soil homogeneity of reclaimed soil. Table 4 lists the degree of dsuch 10 , d50 , the coefficient of inhomogeneity Cu , the porosity, and the water content of the soil after the correlation percentage coefficient copositiongrading of soil with particle size thanshow or equal to 0.25 managementbetween period; the the correlation used aSpearman. Theless results that there is mm or 0.1 mm, d 10, d50, the coefficient of inhomogeneity Cu, the porosity, and the water content of the a significant correlation between the percentage coposition of soil with a particle size less than or equal soil after period; thethe correlation coefficient grading used Spearman. period, The results to 0.25 mmthe or management 0.1 mm, d10 , d50 , Cu , and water content of the soil after the management and show that there is a significant correlation between the percentage coposition of soil with a particle they are unrelated only to the porosity of the soil after the management period. The porosity of the size isless than only or equal 0.25water mm or 0.1 mm, d10, soil d50, C u, and the water content of the soil after the soil related to d50to. The content of the after the one-year management period is only management andcoposition they are unrelated only particle to the porosity of the soil management related to the period, percentage of soil whose size is less than or after equalthe to 0.25 mm, d10 , period. The porosity of the soil is related only to d 50. The water content of the soil after the one-year and d50 . management period is only related to the percentage coposition of soil whose particle size is less than or equal to 0.25 mm, d10, and d50.


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Table 4. Spearman grading correlation coefficient results.

≤0.25 mm

Rho of Spearman

≤0.1 mm

d10

a

−0.967 0.000 19

d50 a

−0.904 0.000 19

Cu a

n

θ

0.532 0.019 19

−0.393 0.096 19

−0.742 a 0.000 19

b

≤0.25 mm

Correlation coefficient Sig. (bilateral) N

1.000 19

0.727 0.000 19

≤0.1 mm


0.727 a 0.000 19

1.000 19

−0.812 a 0.000 19

−0.806 a 0.000 19

0.404 0.087 19

−0.353 0.138 19

−0.365 0.124 19

d10


−0.967 a 0.000 19

−0.812 a 0.000 19

1.000 19

0.914 a 0.000 19

−0.581 a 0.009 19

0.368 0.121 19

0.686 a 0.001 19

d50


−0.904 a 0.000 19

−0.806 a 0.000 19

0.914 a 0.000 19

1.000 19

−0.279 0.247 19

0.484 b 0.036 19

0.611 a 0.005 19

Cu


0.532 b 0.019 19

0.404 0.087 19

−0.581 a 0.009 19

−0.279 0.247 19

1.000 19

0.007 0.977 19

−0.419 0.074 19

n


−0.393 0.096 19

−0.353 0.138 19

0.368 0.121 19

0.484 b 0.036 19

0.007 0.977 19

1.000 19

−0.068 0.781 19

θ


−0.742 a 0.000 19

−0.365 0.124 19

0.686 a 0.001 19

0.611 a 0.005 19

−0.419 0.074 19

−0.068 0.781 19

1.000 19

Note: a represents that when the confidence level (double test) is 0.01, the correlation is significant. is 0.05.

b

represents that the correlation is significant when the confidence level (double test)


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The of correlations The data data of correlations was was formed formed into into aa scatter scatter plot plot with with straight straight lines lines (Figures (Figures 17 17 and and 18). 18). Figure oror equal toto 0.25 mm is Figure 17 17 shows shows that that the thepercentage percentagecontent contentofofsoil soilwith withparticle particlesize sizeless lessthan than equal 0.25 mm basically consistent with the change trend of the C u values and the percentage content of the soil is basically consistent with the change trend of the Cu values and the percentage content of the soil whose particle particle size size is is less less than than or or equal equalto to0.1 0.1mm; mm;dd1010 and and dd50 50 are basically consistent with the change whose are basically consistent with the change trend of the the soil soil water water after after the the management management period, period, and and are are basically basically contrary the change change trend trend trend of contrary to to the of the percentage content of soil with particle size less than or equal to 0.25 and 0.1 mm. Soils with of the percentage content of soil with particle size less than or equal to 0.25 and 0.1 mm. Soils with particle size fine-grained soils, and thethe changes in particle size less less than than or or euqal euqalto to0.25 0.25mm mmand and0.1 0.1mm mmare areallall fine-grained soils, and changes their contents are mainly affected by the seepage of irrigation water in the reclaimed soil during the in their contents are mainly affected by the seepage of irrigation water in the reclaimed soil during period of management, and and therefore theirtheir changes are positively correlated; the value of theofnonthe period of management, therefore changes are positively correlated; the value the uniform coefficient Cu isCuless than 5, indicating that thethe reclaimed non-uniform coefficient is less than 5, indicating that reclaimedsoil soilall allbelongs belongsto to homogeneous homogeneous soil. Thenon-uniform non-uniformcoefficient coefficient reclaimed soil after the management is basically soil. The of of thethe reclaimed soil after the management periodperiod is basically smaller smaller than that of the URS, indicating that the soil becomes homogeneous under the of than that of the URS, indicating that the soil becomes homogeneous under the seepage of seepage water; and water; and theof reduction of the precentage of soil whose particle is or lessequal thanto or0.25 equal to the reduction the precentage content of content soil whose particle size is lesssize than mm 0.25 mm indicates that fine particles have decreased, and the soil is basically composed of coarse indicates that fine particles have decreased, and the soil is basically composed of coarse particles with particles with a good uniformity. Whencontent the fine particle the content the valueparticle of the a good uniformity. When the fine particle decreases, valuedecreases, of the characteristic characteristic size d10 and d50 would be greater, reflecting a coarser particle size of the soil on size d10 and dparticle 50 would be greater, reflecting a coarser particle size of the soil on the whole. Table 4 the whole. Table 4 shows thatofthe content ofafter the reclaimed soilmanagement after the one-year management shows that the water content thewater reclaimed soil the one-year period is corelated period is corelatedcontent to the precentage content of the soil with particle size lessto than equivalent to to the precentage of the soil with particle size less than or equivalent 0.25ormm, as well as 0.25 mm, as well as to d 10 and d50. Figure 17 shows that after the one-year management period, the to d10 and d50 . Figure 17 shows that after the one-year management period, the water content of the water content ofpositively the reclaimed soil istopositively corelated to d10 and d50, andtonegatively corelated reclaimed soil is corelated d10 and d50 , and negatively corelated precentage content to of precentage content of the soil whose particle size is less than or equivalent to 0.25 mm. This indicates the soil whose particle size is less than or equivalent to 0.25 mm. This indicates that the coarser the that thethe coarser thethe soil is, water the higher the will soil water content will be. This is because water content soil is, higher soil content be. This is because the water contentthe of the reclaimed of the reclaimed soil is generally higher at the depth of 30 cm. This position also happens to be the the soil is generally higher at the depth of 30 cm. This position also happens to be the location with location with the content At of fine particles. Atcm, thethe depth of 10 cm, the water content low due lowest content of lowest fine particles. the depth of 10 water content is low due to theisimpact of to the impact of evaporation of the ground, while at this position the particles are relatively finer. evaporation of the ground, while at this position the particles are relatively finer.

Figure 17. Scatter plot with straight lines of percentage content of soils ≤0.25 mm and ≤0.1 mm, d10 , Figure 17. Scatter plot with straight lines of percentage content of soils ≤0.25 mm and ≤0.1 mm, d10, d50 , Cu , and θ. d50, Cu, and θ.

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Figure 18. Scatter plot with straight lines of d and n. Figure 18. Scatter plot with straight lines of d5050and n.

Figure 18 shows that the overall porosity is positively correlated to d50 , indicating that the coarser Figure 18 shows that the overall porosity is positively correlated to d50, indicating that the coarser the particles of the reclaimed soil are, the greater the porosity will be. This is quite opposite to the the particles of the reclaimed soil the greater the porosity be. This quite oppositeuniform, to the general distribution of porosity in are, the soil. This is because, if thewill particle sizesisare completely general distribution of porosity in the soil. This is because, if the particle sizes are completely uniform, the porosity of coarse-grained and fine-grained soils will be the same. However, the porosity of the porosity of soils coarse-grained and fine-grained will be the same. However, porosity of coarse-grained is usually smaller than that ofsoils fine-grained soils, and the pores ofthe coarse-grained coarse-grained soils is usually smaller than that of fine-grained soils, and the pores of coarse-grained soils will be filled with smaller fine particles, while the pores of fine-grained soils will have none or soils will be filled with smaller particles, while thereclaimed pores of coarse-grained fine-grained soils have than nonethat or less smaller fine particles to fill fine in. The porosity of the soilwill is larger less smaller fine particles to fill in. The porosity of the reclaimed coarse-grained soil is larger than that of the fine-grained soil, because the fine particles in the coarse-grained soil are carried into the deeper of theof fine-grained soil,soil, because the fine in the coarse-grained soil are carried into the deeper part the reclaimed resulting in aparticles bigger pore volume and porosity. part of the paper reclaimed resulting in a bigger pore volume and porosity. This onlysoil, includes the uncompacted and one-compaction circumstances, and there were This paper only includes the uncompacted and one-compaction circumstances, there of were no tests for the situation of multiple compactions. In the future period of this study, and the effect the no tests for the situation of multiple compactions. In the future period of this study, the effect of the number of times of compaction on the change in granulometric composition of the reclaimed soil after number of times of compaction on the change in granulometric composition of the reclaimed soil the management period will be carried out. According to the results of the granulometric composition after periodmanagement will be carried out.the According to the results of the granulometric of thethe soilmanagement after the one-year period, most important factor affecting the change in composition of the soil after the one-year management period, the most important factor affecting granulometric composition is the transport of the water in the unsaturated zone of the reclaimed the change in granulometric composition is the transport of the water in the unsaturated zone of the soil. The future research could be conducted with a focus on the transport mechanism of the water in reclaimed soil. The future research could be conducted with a focus on the transport mechanism of reclaimed soil under different overlaying thickness and compaction circumstances. the water in reclaimed soil under different overlaying thickness and compaction circumstances. 4. Conclusions 4. Conclusions Studying the distribution of fine particles in reclaimed soil is very important for mined land Studying fine particlesexperimental in reclaimedmethods soil is very important mined land reclamation. the Thisdistribution paper usesofgeotechnical to analyze theforgranulometric reclamation. This paper uses geotechnical experimental methods to analyze the granulometric composition and the index of physical properties of the reclaimed soil in seepage conditions after a composition and the index of physical of the reclaimed soilanalysis, in seepage after a one-year management period. Throughproperties experimental results and data weconditions can conclude that one-year management period. Through experimental results and data analysis, we can conclude that the content of fine particles in reclaimed soil at the depth of the interface between the soil and waste the content fine particles in reclaimed soilmanagement at the depth period; of the interface between the soil and rock varies of greatly under seepage after the the thicker the overlaying soilwaste is, the rock varies undercontent seepage the management period; theof thicker the overlaying is, the higher the greatly fine particle atafter this depth. The sampling depth reclaimed soil has a soil significant higher thethe fine particle content at this depth. The sampling depth of significant reclaimed soil has a significant effect on granulometric composition of reclaimed soil. The most difference is between effect on the granulometric composition of reclaimed soil. The most significant difference is between the depth of 70 cm and 30 cm. The fine particle content varies at different depths of reclaimed soil. the depth of 70 cm and 30 cm. The fine particle content varies at different depths of reclaimed soil. The fine particle content at the depth of 10 cm is not much different from that of the URS. The fine The fine particle at thesoil depth of 10 cmbeen is not much different of of the10URS. fine particle content content of reclaimed which has compacted once atfrom the that depth cm isThe slightly particle content has been compacted once at depth of 10 cm lower is slightly higher than thatofofreclaimed the URS. soil The which fine particle content at the depth ofthe 30 cm is generally than higher than that of the URS. The fine particle content at the depth of 30 cm is generally lower than that of the URS, and reclaimed soil generally becomes coarser, and the fine particle content of the that of the URS,reclaimed and reclaimed soil generally becomes coarser, fine content particle at content of the uncompacted soil decreases more significantly. The and fine the particle the depth of uncompacted reclaimed soil decreases Theparticle fine particle content at the depth at of the 50 50 cm is slightly lower than that of themore URS.significantly. Finally, the fine content increases sharply cm is slightly lower that of thethat URS. Finally, depth of 70 cm, and than is greater than of the URS.the fine particle content increases sharply at the depth of 70 cm, and is greater than that of the URS.

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17 o

By comparing the fine Bygrain comparing By comparing contentthe of reclaimed fine the fine graingrain content soil content withofthe reclaimed ofphysical reclaimed soil properties with soil with theofphysical the soil, physical weproperties canproperties of soil, of soil, we c 17 of 18 see that the fine particle see that see content that the fine the affects fine particle the particle physical content content properties affects affects the such physical the physical as the properties homogeneity, properties suchsuch as porosity, the as homogeneity, the homogeneity, poros po and water content; the andoverall and water water change content; content; isthe thatoverall the theoverall coarser change change theis particles that is that the coarser are, the coarser the the more particles theuniform particles are, the are, the soil more the more uniform uniform the s By comparing fine grain content ofthe reclaimed soil withand the physical properties ofwill soil,be. we particles, the higherthe the particles, water particles, the content, higher the higher and the water the larger water content, the content, porosity and the will larger the be. larger the porosity the porosity will be. can see the fine particle affects physical properties such as guaranteeing the porosity, Thethat results of this paper Thecontent The results can results provide of this ofathe this paper basis paper for canguaranteeing provide can provide a basis athe basis for survival for homogeneity, guaranteeing rate of vegetation the survival the survival in rate rate of vegetation of vegeta and water content; the overall change is coarser the are, the more uniform the soil the reclaimed area of the Xinjiang reclaimed the reclaimed during areathe area ofthat management Xinjiang ofthe Xinjiang during during period. theparticles management the management period. period. particles, the higher the water content, and the larger the porosity will be. Author Contributions: Author Z.Z. Author and Contributions: W.S. Contributions: conceived Z.Z. Z.Z. and main W.S. and idea W.S. conceived of the conceived paper thethe main and thesurvival designed main idea idea of the the ofpaper the test scheme; and designed andK.W., designed thescheme; test schem K. The results of this paper can provide a the basis for guaranteeing rate of paper vegetation in the test G.T., and X.L. performed G.T., the G.T., and test X.L. and scheme; performed X.L. performed K.W. and the test G.T. the scheme; test analyzed scheme; K.W. the K.W. data; and G.T. and Z.Z. G.T. analyzed wrote analyzed the the paper; data; the data; W.S. Z.Z. worked Z.Z. wrote wrote the paper; the paper; W.S. W.S. work the reclaimed area of Xinjiang during the management period. Processes 2018, 6, 201

to modify figures and proofread to modify to modify the figures revised figures andversion. proofread and proofread the revised the revised version. version.

Author Contributions: Z.Z. and W.S. conceived the main idea of the paper and designed the test scheme; K.W., Funding: This researchFunding: wasFunding: funded Thisby This research theresearch Natural was was funded Science funded by Foundation the byNatural the Natural of Science Xinjiang Science Foundation (Grant Foundation No.of 2018D01C061) Xinjiang of Xinjiang (Grant (Grant No. 2018D01C0 No. 2018D G.T., and X.L. performed the test scheme; K.W. and G.T. analyzed the data; Z.Z. wrote the paper; W.S. worked to and the figures National Natural andScience the and National the Foundation National Natural Natural of China Science Science (Grant Foundation Foundation No. 41472268). of China of China (Grant (Grant No. 41472268). No. 41472268). modify and proofread the revised version.

Conflicts This of Interest: Conflicts authors Conflicts ofdeclare Interest: ofthe Interest: no The conflict authors The of authors interest. declare declare no conflict no conflict of interest. of interest. Funding: researchThe was funded by Natural Science Foundation of Xinjiang (Grant No. 2018D01C061) and the National Natural Science Foundation of China (Grant No. 41472268).

References References References Conflicts of Interest: The authors declare no conflict of interest. 1.

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