Available online at www.sciencedirect.com
ScienceDirect Procedia Engineering 165 (2016) 308 – 314
15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development”
The methods use of the heterogeneous engineering-geological conditions diagnostic during shield underground tunneling Evgeny Pashkin a, Sergei Mazein a,* a
b
Russian state geological prospecting University, Russia Executive management of Russian Tunneling Association, Russia
Abstract
An analysis of using modern methods of heterogeneous engineering-geological conditions diagnostic during shield underground tunneling. Measurement of technological indicators penetrations may use to diagnose address characteristics of ground array: groundwater flow and level, as well as the type of soil and its physical properties (density and specific cohesion). Level sensors and suspension data may determine the filling speed camera dirt water at different pressures of air in the chamber. This water rate, measured in a particular location and corrected to normal atmospheric pressure conditions, can be used to select special techniques of tunnel structures in the vicinity of the measurements. Excavation volume measurement to diagnose the actual situation of the underground water level and adjust modes of penetration for improving the sustainability of the face. Information exploration wells from the surface can complement the geological descriptions of excavated material from the shield, and the ratio of the allocated two lithological differences horizontal bedding can be used to define boundaries between them in the vertical face plane. To diagnose soil density determined that the amount recoverable sandy soil per cycle has a direct relationship with a significant measure of the density of sand samples. Also during the sinking of the measured torque indicators rotor can diagnose value of specific cohesion of conglomerate rocks in the mine. ©2016 2016Published The Authors. Published by Elsevier © by Elsevier Ltd. This is an openLtd. access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Peer-review under theSustainable scientific committee of the 15th International scientific conference “Underground Urbanisation as a Urbanisation as aresponsibility Prerequisiteoffor Development. Prerequisite for Sustainable Development Keywords: shield tunneling, predictive diagnosis, groundwater level (GWL), extractable soil, process parameters.
* Corresponding author. Tel.: +7-495-608-80-32 E-mail address:
[email protected]
1877-7058 © 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license
(http://creativecommons.org/licenses/by-nc-nd/4.0/). Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development
doi:10.1016/j.proeng.2016.11.705
Evgeny Pashkin and Sergei Mazein / Procedia Engineering 165 (2016) 308 – 314
1. Introduction The emergence of new technologies in the field of tunneling equipment led to the presentation of adequate approaches and requirements to use engineering-geological information (regarding its optimality, targeting, redundancy) and improve the technological capabilities of mechanized shield TBMS. Currently identified some tunneling indicators the most dependent on interactions with geological conditions: extractable soil weight, cutterhead force and torque, etc. When the excluded indicators, of which there is no need, for example, the rate of filtration, as the tightness of the working part of the shield and traversed the tunnel part excludes groundwater into the tunnel. The specifics of the technology to the construction of tunnels using shield TBMs substantially changes not only to the quality and quantity of geological information about the array of subterranean shopping, but also to the use of new methods of diagnosing engineering-geological conditions of tunnel construction and structures. Excavation of underground tunnels in Moscow different sections is carried out tight shields with Earth Pressure Balance and universal set of cutting tools for tunneling in sandy, clayey and rocky grounds (Fig. 1). In addition, modern boards are equipped with the latest measuring devices to determine indicators of shield technology associated with reactions of various ground arrays. But such information feedbacks (influence on measured parameters array property technology) -unaddressed and investigated only sporadically. So to put such research on a permanent basis, it is proposed to examine the possibility of using methods of diagnosing heterogeneous and complex engineering-geological conditions with shield tunneling currently intensively for subways of Moscow.
Fig. 1. EPB TBM dimensions.
2. Diagnostics to identify complex engineering and geological conditions in shield tunneling Moscow area studied sufficiently not only by the number of wells selected samples of experienced field research, but many cases of emergencies. Emergency cases have opened a weak "painful" places in collaboration built tunnels and vulnerabilities in the geological space city, which created difficulties in drilling the tunnels. For example, Flint nodules formed by quartz, or chalcedony in the limestone of the upper and middle carbon in the form of lenses and the origin of power up to a few tens of centimeters, and sometimes up to 1.0 m, rarely as ball diameter of 8-12 cm are not allowed in 60-ies of the last century to use in these sediments tunnel shields. This and dips in the development zones paleo karst (span tunnels on theatre square); this collapse and dips in areas crossing flooded man-made soil filling the pre-glacial and pre-jurassic valleys of the Moskva River and its
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tributaries (the tunnel in the vicinity of the factory "Red Rose" and B. Dmitrovka Street); This localization and extent of erosive pull-quotes, linear and areal Flint, some wandering boulders and such, not yet identified, complications. Thus, the identification of such "painful" places becomes the prerogative of recognizing and identifying such sites based on the definition of the substance of these complications. This can help explore fully the traits and characterize confined weakness in the structure of the studied geological environment of the city. Moscow is, first of all, a number of unusual, exceptional properties and forms of expressions of different geological manifestations. To create safe conditions for the construction and operation of underground tunnels are important not only created conditions for rapid response emergency liquidation modern technical facilities, which in itself is important, but more importantly to identify locations and nature conditions provoking accidents for their timely detection and prevention ahead. This unconditional aid can have methods of diagnosis of conditions that generate emergency situations that could create an emergency situation in the production process works. In such cases, priority should belong to the preventive and pre-emptive action against occurrence of emergency situations. To accomplish this, there is a need to develop ways to diagnose species and degree of difficulties and risks under the terms of the interaction of tunnel construction technology used with the complexities of the geological environment of the city. Because diagnosis is included in the mode of production activities, it should be extended to the area of predictive background, including being part of the geological environment (as an object of forecasting) and conditions that determine the most difficult and dangerous areas. This forecasting stage should be regarded as predictive diagnosis. In this phase, systematic description of the forecast background in order to identify trends, complicating conditions of openings, as well as the development of diagnostic routines for identifying the nature and location of dangerous sites and for decisions on management of correction sinking tunnel. Modern methods of diagnosing the condition array rocks on the allocation and identification of the type and degree of heterogeneity and complications, leading to difficulties in applying the latest tunneling technology, unfortunately not developed. Only the first steps. In the long term requires a set of diagnostic methods of recognition of the basic signs, complicating the construction of tunnels in Moscow, and the most common take to diagnose "painful" places. One of those places that represent the projected background serve Planar erosion valleys adjacent to the r. Moskva great valley . They represent a trough developed mechanical erosion of carbonate rocks up to the horizon of strong silicified limestones and siliceous areal concretion, excluded the further development of the process of erosion. At the end of the erosive process, these hollows were filled with eluvia deposits and technological inputs. Boundary conditions between these flooded savings and silicified limestones can be quite complex for tunneling technology. This is evidenced by the forecast emergency situations that may arise in the future tunnel station of Kuntsevskaya" on the Western front the third transfer path after crossing the Moskva River Valley [1]. 3. Examples of the predictive diagnosis use Look at how technological parameters measured tunneling, possibly used as a predictive diagnosis targeted characteristics of ground array: water flow and ground water level marked in [2, 3], type of soil and its physical and mechanical properties (density and specific adhesion) that are listed in [4]. 3.1. The predictive diagnosis inflow on the rate of suspension level raising in the shield chamber When designing tunneling using TBM is no longer necessary to evaluate their filtration properties, because you no longer need, for example, in the definition of water inflows in sealed, what are the tunnels shield method of construction. However, when sinking support tunnel structures (approaching and connecting formulation), constructed the mountain way, avoid water inflows cannot be expected. So in this case when you select special techniques you need to know the amount of penetration of water inflows in tunnels and construction of the adjacent auxiliary facilities for the choice of the most appropriate ad hoc method.
Evgeny Pashkin and Sergei Mazein / Procedia Engineering 165 (2016) 308 – 314
For example, you can set the places of contiguity predictive diagnosis of water, for example, by raising the level of velocity in slurry shield chamber bashing. For this shield to stop in the future site of an adjunction with project formulation, establish the level of the suspension in a cell at the level axis shield (½). There is an opportunity to serve bentonite suspension not only in camera of slurry shield, but also EPB shield. Level sensors and suspension data may determine the rate of filling chamber groundwater under different air pressures in the chamber. This water rate, measured in a particular location and corrected to normal atmospheric pressure conditions, can be used to select special techniques of sinking tunnel structures in the vicinity of the measurements. 3.2. Definition of groundwater level on the weight change of the extractable soil Positioning method in detail the level of groundwater (GWL) to change the volume and weight of excavate was described previously [2]. Here the main condition is the intersection of tunnel groundwater level, i.e. the transition from soil-cement for flooded layers and vice versa. Such crossing in the subway construction quite often happens at the start and finish of the shields of relatively shallow open pits and falling of the central part of the subway tunnels. As demonstrated by monitoring the amount of dredging, the move of the shield under the GWL is accompanied by a gradual increase in the volume of air with lessening excavate its porosity during lifting GWL in the tunnel (Fig. 2). Research crossing GWL in tunnel (project S-353) showed that the change in the volume indicator excavate V can be used when updating the provisions of crossed construction, elaboration of GWL, pressure loading calculation [3].
a)
b)
Fig. 2 - Dependence of the volume (EPB-shield) and the weight (slurry-shield) excavated soil per cycle from the tunneling length: а – the slurryshield in the project S-353, b – the EPB shield in the project S-328-3
3.3. Definition of groundwater level on the weight change of the extractable soil The dependencies between the budgeted parameters and parameters of soil properties based on the materials of exploratory wells at carrying out geotechnical surveys and stock materials differ from the actual values because the interaction Panel breed is carried out according to the scheme of amalgamation of various lithological differences peculiar mixture of conglomerate and depending on the shield diameter and the number of layers and their power they are developed at the same time, forming different from specified, communication structure [5]. In this connection, to establish these dependencies in the process of sinking TBM with conveyor conglomerate mixture samples should be collected to assess its properties emerging in the process of developing different soils in the tunnel face and defining the scope of the forecast background. A set of such dependencies will after aggregation find certain combinations of soils of different composition to refine the engineering-geological section in difficult geological conditions, such as in the areas of the erosive pullquotes.
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On the one hand, when designing the road must TBM strive to rationalize the amount of research, actively using archived data from wells in "calm" geological conditions and exploring more detailed geological anomalies in order to avoid emergency situations (Fig. 3).
Fig. 3--Profile and plan of the left tunnel in the Depot "Likhobory".
Frequency of drilling exploration wells in the definition of "calm" geological conditions left the tunnel in the Depot "Likhobory" turned out to be even higher than in determining geological anomalies-erosive cutting Riverbed r. Likhoborka, however the entrance zone broke anomalies shield tunneling technology [4]. On the other hand, information exploration wells from the surface can complement the geological descriptions of excavated material and the ratio of the allocated two lithological differences horizontal bedding can be used to define boundaries between them in the vertical plane.
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3.4. Identification of forecast background dependences with tunneling process parameters On the status and properties of the soil, when to retrieve sinking, can be largely judged by the values of certain physical and mechanical characteristics, for example, its density. The value of this indicator reflects the extent of watering soil massif and correlates with performance in bulk or weight to retrieve soil in tunneling cycle. For example, it is established that the amount recoverable sandy soil per cycle has a significant direct relationship with sand density in samples. This illustrates the dependency graph in Fig. 4 received the project of the second Serebryany Bor tunnel.
Fig. 4. Linear dependence of the taken volume V (m3/cycle) of deaerated sand on the average density ρ (g/cm3) of soil samples.
When drilling the same tunnel was installed, this dependence of cutterhead torque m from weighted average specific soil adhesion in the bottom (Fig. 5). Obtained during the excavation of the tunnel information on measured cutterhead torque indicators was used to forecast specific soil adhesion values diagnosis conglomerate in the tunnel face.
Fig. 5. Linear dependence of cutterhead torque M (MN·m) on the average specific cohesion of soil C.
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4. Conclusion Engineering-geological conditions of tunnel construction in Moscow are complicated not only by the heterogeneity of rocks and their structure, but the main thing is that the terms of the interaction with these inhomogeneity TBM technologies have a negative impact on the rate of sinking tunnels. Becomes relevant use of new methods of diagnosing engineering-geological conditions of tunnel construction and tunnel structures. This diagnosis can be measuring devices to determine indicators allowing TBM shield technology associated with reactions of various ground arrays. According to the results of the work can be done the following conclusions: x Updated object structure prediction tunneling conditions selection difficult and dangerous sites, which are considered as predictive diagnosis, whose task is to draw up the diagnostic routines to identify dangerous sites and decision-making control correction sinking. x Shows how technological parameters used as predictive diagnosis of the State of soil Massif in relation to its water abundance, the situation of the groundwater level, the composition of the soil conglomerate mixes and its density. x The use of diagnostic methods for heterogeneous engineering-geological conditions in hollow sinking would enhance the effectiveness of the design-build tunnels under constant replenishment of information in the process of technological and geological monitoring. References [1] S.V. Mazein, V.V. Lekht, A.D. Prudnikov, Geotechnical condition analysis during choosing of subway tunnel laying to improve technical and economic characteristics of constructing and its safety, Metro and tunnels. 6 (2015) 22-26. [2] S.V. Mazein, M.A. Potapov, Monitoring of the Soil Pressure and the Volume of the Watered Massif Excavation for Safe EPB Tunneling, Occupational safety in industry. 11 (2012) 58-63. [3] S.V. Mazein, A.S. Voznesensky, TBM-monitoring of soil pressure and watered extractable volume, 6th International Symposium on Tunnels and Underground Structures in SEE 2016 „Urban Underground Structures in Karst“, March 16-18, Radisson Blu Resort, Split, 2016. [4] E.М. Pashkin, S.V. Mazein, E.B. Ryabov, Optimization of geological researches for subway planning in Moscow, SEE Tunnel – Promoting Tunneling in SEE Region. Proceedings of the ITA-AITES World Tunnel Congress 2015, 22-28 May, Dubrovnik, 2015, pp. 692-693. [5] E.M. Pashkin, S.V. Mazein, E.B. Ryabov, Technological typing development of geological conditions in Moscow underground construction, Metro and tunnels. 5 (2015) 13-15.
