Ain Shams Engineering Journal (2013) 4, 709–716
Ain Shams University
Ain Shams Engineering Journal www.elsevier.com/locate/asej www.sciencedirect.com
CIVIL ENGINEERING
Finite element model of Cairo metro tunnel-Line 3 performance S.A. Mazek *, H.A. Almannaei
1
Civil Engineering Department, Military Technical College, Cairo, Egypt Received 20 June 2012; revised 14 January 2013; accepted 11 April 2013 Available online 15 May 2013
KEYWORDS Tunnels; Surface settlement; Numerical modeling and analysis; Displacement; Design; Deformations
Abstract The Greater Cairo metro-Line 3, the major project of underground structure in Cairo city, Egypt, is currently under constructed. Ground movement is expected during the construction with tunneling boring machine as Cairo metro tunnel passes through sand soil. In the present study, finite element model is used to model tunnel system performance based on the case study. An elasto-plastic constitutive model is adopted to represent the soil behavior surrounding the tunnel. The effects are expressed in terms of surface displacement and soil stress change caused by tunneling. The subsoil stresses undergo three phases of change. At these phases, the loading steps of the tunnel construction are predicted using the 2-D finite element analysis. Ground movement and construction influence are obtained by the numerical model. A comparison is made between the computed tunnel performance and the observed behavior. The comparison reveals a good agreement between the calculated and the observed values. 2013 Ain Shams University. Production and hosting by Elsevier B.V. All rights reserved.
1. Introduction Tunneling is an effective solution to overcome high density population challenges such as transportation and utilities activities, so it is increasingly used. Tunnels are used for several purposes such as underground railways, water and power supply, and sewage [1,2]. Several tunnels have been constructed * Corresponding author. Tel.: +20 1226391261. E-mail addresses:
[email protected] (S.A. Mazek), hsnos@ hotmail.com (H.A. Almannaei). 1 Tel.: +20 1144332266. Peer review under responsibility of Ain Shams University.
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around the world and in Egypt to solve the transportation problems such as the Greater Cairo metro and the El-Azhar road tunnels [1,3]. These tunnels are considered as major projects in Cairo city. There are technologies to assist in excavation such as tunneling boring machine (TBM), new Austrian tunneling method (NATM), immersed-tube tunneling system, and cut and cover method [4]. It is necessary to investigate the geotechnical problems for better understanding the performance of the tunnel system. Many geotechnical problems were encountered during the construction of the Greater Cairo metro, El-Azhar road tunnels, and the Greater Cairo sewage tunnel [5,6]. Most problems are related to the damage of surrounding buildings due to surface and subsurface ground subsidence [5,6]. Finite element method is considered as the most appropriate analytical technique to solve geotechnical problems [7,8].
2090-4479 2013 Ain Shams University. Production and hosting by Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.asej.2013.04.002
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Darabi et al. [9] presented an appropriate model to predict the behavior of the tunnel in Tehran No. 3 subway line. They employed empirical methods to determine the variation of radial displacements along the longitudinal direction of a tunnel. They also determined the tunnel deformation using numerical analyses. Elsayed [10] used 2-D finite element analysis to model two phases of tunneling process. First phase, the excavation phase, was responsible to determine the pre-lining rock mass deformations and the reduced in situ stresses. Second phase, the interaction phase, modeled the compatibility of the rocklining system. The deformations and stresses of the rock-lining system and the final rock mass pressure acting on the lining were determined. Cavalaro et al. [11] analyzed the influence of the contact deficiencies between the segmented tunnel lining during the construction of tunnels and the consequent damage procedure with TBM. They used the finite element analysis to simulate the contact deficiencies. Kivi et al. [12] investigated settlement control of large span underground station in Tehran metro using 3-D finite element analysis. They discussed the impact of central beam column (CBC) on the rigidity of the supporting tunnel system. Liu et al. [13] discussed the ground movement property caused by shield tunneling and expanding construction. Ground movement and construction influence were obtained by numerical model. Wang et al. [14] used finite element analysis to predict surface settlement above tunnel in clay till. The influence of drainage condition on surface settlement was investigated. Wang et al. [15] applied finite element analysis to investigate the effect of tunneling induced ground movement on buried pipelines. Modeling of geotechnical properties and tunneling procedure is a sophisticated numerical problem [8,16–19]. The Greater Cairo metro tunnel-Line 3 is presented and discussed in the present study as a case study. Line 3 has been constructed since 2011. 2-D finite elements analysis (FEA) is used to understand performance of tunnel system based on a case study. The 2-D FEA is also adopted to estimate surface
Figure 1
settlement and vertical displacement at different locations and levels around tunnel system. The constitutive model for this analysis utilizes elasto-plastic materials. A yielding function of the Mohr–Coulomb type and a plastic potential function of the Drucker–Prager type are employed. A linear constitutive model is employed to represent the tunnel liner. Model boundaries and volume losses (VL) are discussed to understand the performance of the metro tunnel. The associated stress changes in soil are studied and presented based on different loading steps of the tunnel construction. The results obtained by the 2-D FEA are compared with those obtained by the field measurement to assess the accuracy of the 2-D finite element model. There is a good agreement between readings obtained by both the FEA and the filed data. 2. Greater Cairo metro-Line 3 (case study) The Greater Cairo metro-Line 3 passes through a wide range of soil condition [20]. Line 3 moves underground from Abbasia station to Attaba station. Line 3 is 4.3 km long. Fig. 1 shows the plan of the Greater Cairo metro-Line 3 [20]. The internal diameter of tunnel liner is 8.30 m, as shown in Fig. 2. Based on the project document prepared by the NAT [20], the soil profile is analyzed and discussed to use soil properties at the 2-D finite element model. Line 3 tunnel was excavated under the central region of Cairo city. Line 3 was built on alluvial deposits through the Nile valley. 3. Soil and metro tunnel interaction The analyzed project area lies within the alluvial plain, which covers the major area of the lowland portion of the Nile valley in Cairo vicinity [20]. Five distinct soil layers are encountered through the case study [20]. Site investigations along Line 3 alignment indicate that the soil profile consists of a surficial fill layer ranging from 2 to 4 m
Plan of the Greater Cairo metro (Line 3) (after NAT, 2009).
Finite element model of Cairo metro tunnel-Line 3 performance
Figure 2
Cross section of the Greater Cairo metro (Line 3) (after NAT, 2009).
in thickness. The fill is followed by upper sand layer. The upper sand layer is varied from dense to very dense poorly graded silty sand with a thickness varying from 2.1 m to 6.6 m. Underneath the upper sand layer, the soil is very dense sand. This sand layer is called middle sand below the upper sand layer. The thickness of the middle sand layer is varied from 5.5 m to 10 m. Beneath the middle sand layer, there is a very stiff silty clay layer with thickness of the layer which is varied from 1.5 m to 4.4 m. Below the silty clay layer, the soil layer is sand soil. This sand layer is called lower sand layer. The lower sand layer is very dense gravely sand. The lower sand layer is extended down to bedrock. The ground water table varies between two meters to four meters from the ground surface. The main soil parameters required to model the performance of the case study are analyzed by the authors and presented in Table 1 based on the soil report prepared by the National Authority for Tunnels (NAT) [20]. Fig. 3 shows the cross section of soil parameters. The tunnel liner is composed of 50-cm thick segments. The segments joints are never aligned along the tunnel, and the thickness reduction
Table 1
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is not as local construction as it is simulated in the model, which is conservative. The computed normal forces and bending moment values must comply with the strength of the 50-cm thick reinforced segments and the 30-cm thick joints between the segments. The tunnel liner is assumed to behave in a linear manner in the 2-D FEA. The characteristic of the tunnel liner is tabulated in Table 2. Effective stress is used in the finite element analysis, as the metro tunnel is located in the lower sand layer. The variation of soil modulus (Es) with confining pressure is related to effective pressure based on Janbu’s empirical equation [21] as presented in Eq. (1). The different soil parameters (m, n) are selected to simulate the behavior of different sand soil types [22,23]. n r3 Es ¼ mPa ð1Þ Pa In which, modulus number (m) and exponent number (n) are both pure numbers, Pa is the atmospheric pressure expressed in appropriate units, and r3 is an effective confining pressure.
Geotechnical properties in Central Cairo city-Line 3 (after NAT, 2009).
Layer 3
Bulk density cb (t/m ) Drained Poisson’s ratio ms Effective angle of initial friction (/) Effective cohesion, C (t/m2) Standard penetration (blows/0.3 m) Modulus number (m) Exponent number (n) Over consolidation ratio (OCR) Coefficient of lateral earth pressure, K0
Fill
Upper sand
Middle sand
Silty clay
Lower sand
1.7 0.3 27 0 4–20 300 0.74 1 1
1.9 0.3 36 0 28 400 0.55 – 0.412
1.95 0.3 38 0 32 500 0.52 – 0.385
1.8 0.35 29 0 13–15 325 0.6 1.5 0.8
1.95 0.30 38 0 35 400–700 0.5–0.6 – 0.385
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Figure 3
Cross section of soil parameters along the Greater Cairo metro-Line 3 tunnel.
4. Finite element model of Line 3 Table 2 Mechanical properties of metro tunnel liner (Line 3) (after NAT, 2009). Type Tunnel liner
Eb (t/m2) 6
2.1 · 10
t (cm)
Fc (t/m2)
c (t/m3)
V
50
4000
2.5
0.20
The construction of the metro tunnel is under the initial in situ stress condition. The excavation of the metro tunnel causes the soil around the excavated tunnel to respond in an unloading manner, and unload moduli are appropriate during this stage. Under the unload-reload condition, the ratio of the unload and reload modulus (Eur) to the vertical drained modulus (Ev) is used and considered to be two for sand soil [23,24]. A shear modulus (Gvh) is used in the finite element analysis. The ratio of the shear modulus to the vertical modulus Gvh/Ev is about 0.35 in initial loading condition for sand. In unloading condition, the Gvh/Ev ratio is about 0.25 for sand.
The finite element computer program (COSMOS/M) is used in the present study [25]. The finite element model (FEM) takes into account the effects of the vertical overburden pressure, the lateral earth pressure, the non-linear properties of the soil, and the linear properties of the metro tunnel liner. The numerical modeling of the metro tunnel must reflect the characteristic of the ground continuum and the metro tunnel. In addition, the interface between the soil media and the tunnel liner should be idealized in the numerical model. 2-D plane strain elements are used for modeling the soil media and 2-D beam elements for modeling the metro tunnel liner. Three-node triangular plane strain elements are adopted to simulate behavior of the soil media. The soil, the metro tunnel liner, and the interface medium are simulated using appropriate finite elements. The 2-D beam element and the triangular plane strain element interface is used between the soil media and the tunnel liner to ensure the compatibility conditions at the interface between them as well as the associated stress and strains along the interface surface.
Finite element model of Cairo metro tunnel-Line 3 performance The horizontal plane at the bottom of the mesh represented a rigid bedrock layer, and the movement at this plane is restrained in all directions. The vertical boundaries of the 2-D finite element model are restrained by roller supports to prevent a movement normal to the boundaries. The movement at the upper horizontal plane is free to simulate a free ground surface. The 2-D finite element mesh is shown in Fig. 4. The finite element analysis is carried out to simulate the construction of Line 3. The stress changes in surrounding soil due to tunneling are investigated to study the detailed soil behavior around the metro tunnel. The stresses in the subsoil have undergone three phases of change. At these phases, the loading steps of the metro tunnel construction are simulated using the 2-D finite element analysis. First, the initial principal stresses are computed with the absence of the metro tunnel. Second, the excavation of the metro tunnel is modeled by means of the finite element method. The excavation is simulated by the removal of those elements inside the boundary of the metro tunnel surface to be exposed by the excavation. The excavated tunnel boundary is free to move until the soil comes into contact with the metro tunnel liner resulting from volume loss. The volume loss is considered in this study. Third, the calculated changes in stresses are then added to the initial principal stresses computed from the first phase to determine the final principal stresses resulting from the metro tunnel construction. Fig. 5 shows final vertical stress around the metro tunnel system. The initial in situ stresses before tunneling are calculated and plotted in Fig. 6 at the right-hand side. The vertical stress change after tunneling is calculated and shown in Fig. 6 at the left-hand side. The results show that as the soil depth beneath the invert of the metro tunnel exceeds three times the tunnel diameter, there is no change in the soil stress due to tunneling process, as shown in Fig. 6. Based on the proposed 2-D FEM, the calculated vertical stress change in soil due to tunnel construction at 54 m below ground surface level is equal to zero value. At 54 m below the ground surface level, there is no soil displacement occurred due to tunneling. The results also reveal that the soil above the crown of the metro tunnel settles downward as the final vertical stress moves downward. The soil under the invert of the metro tunnel excavation heaves as the final vertical stress moves upward. 5. Geometric model boundaries A parametric study is conducted to choose the suitable geometric boundaries of the 2-D numerical model. The 2-D
713 numerical model should reflect the behavior of the metro tunnel in the field. The 2-D finite element mesh models soil block width and depth in x and y directions, respectively, as shown in Fig. 4. The soil media are modeled and simulated using an elasto-plastic constitutive model. A yielding function of the Mohr–Coulomb types and a plastic function of the Drucker– Prager type are adopted in this study [26]. At the plain strain condition for soil media, the Drucker–Prager model can be used to simulate the soil behavior at the 2-D FEA [26]. The element size is chosen to be three meters along the outer boundary of the soil block. The element size is chosen to be one meter along the boundary of the tunnel liner. The diameter of metro tunnel is 9.15 m. Numerical analysis is adopted for the metro tunnel located at 23 m depth from the ground surface, as shown in Fig. 1. The volume loss (VL) is the ratio of the difference between excavated soil volume and tunnel volume over excavated soil volume. In this section, the parametric study assumes volume loss to be 3%. In the present study, volume loss is studied and varied from 1.5% to 4.5% as discussed later in Section 6. The suitable geometric boundaries (model width and model height) are studied to reflect performance of tunnel system. Based on soil stress change along geometric model boundaries, the parametric study is conducted to determine the suitable dimensions beyond which no changes in soil stress and vertical displacement are occurred. In this study, the model width is varied from 40 m to 120 m. The calculated surface settlements of the metro tunnel against different model widths are shown in Fig. 7. The calculated crown settlement of the metro tunnel-Line 3 versus different model widths is also presented in Fig. 8. The calculated invert heave of the metro tunnel against different model widths is again presented in Fig. 9. Based on the finite element analysis, the 100-m model width is chosen for the rest of 2-D analysis to reflect the performance of the metro tunnel system beyond which no change in vertical displacement and soil stress is occurred. 6. Volume loss impact The suitable volume loss is studied to reflect the performance of the metro tunnel system-Line 3. The 100-m model width and 54-m model height are studied using the 2-D FEA based on different volume losses. The volume loss (VL) is ranged from (1.5% to 4.5%) [1]. In the presented study, the VL is varied from 1.5% to 4.5%. Surface settlement due to construction of the metro tunnel is calculated by the 2-D FEM. The calculated surface settlement against different volume losses is shown in Fig. 10. The results show that the increase in the volume loss leads to increase the surface settlements due to tunneling. The volume loss of 3% is chosen to practically reflect the performance of the metro tunnel system-Line 3. 7. The Greater Cairo metro tunnel-Line 3 performance
Figure 4 Line 3.
2-D finite element model of the Greater Cairo metro-
Based on the previous study, the 2-D non-linear finite element analysis is used to predict performance of the Greater Cairo metro tunnel-Line 3 to assess the accuracy of the numerical model (Line 3). The numerical results are compared with the recorded field measurement. The comparison is presented
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Figure 5
Calculated vertical stress around the metro tunnel system.
Figure 8 Calculated crown settlement of metro tunnel against different model widths due to tunneling.
Figure 6 Calculated vertical stress change before and after tunneling (The Greater Cairo metro tunnel-Line 3), Notes. point (1) shows that the calculated vertical stress change in soil due to tunnel construction at 54 m below ground surface level is equal to zero value.
Figure 9 Calculated invert heaves of metro tunnel against different model widths due to tunneling.
Figure 7 Calculated surface settlement against different model widths due to tunneling.
between the calculated results and the measured values at the ground surface in case of 3% volume loss. The comparison between the calculated results using the 2-D FEA and the mea-
sured values results is presented in Fig. 11. The study shows that the results calculated by the 2-D FEA have a good agreement with those obtained by the field measurements. However, this comparison is used to assess the accuracy of the proposed 2-D finite element model. The calculated surface settlement along centerline of Line 3 is shown in Fig. 12 at different levels. The crown settlement of the metro tunnel is calculated and presented in Fig. 12. The invert heave of the metro tunnel is calculated and shown in Fig. 12. The results show that the soil above the crown of
Finite element model of Cairo metro tunnel-Line 3 performance
715 8. Conclusions A 2-D finite element analysis is used to understand the performance of the metro tunnel system-Line 3. The analysis takes into account the change in stress, the non-linear behavior of the soil, and the construction progress. The following conclusions can be drawn regarding the performance of the metro tunnel under the effects of different factors.
Figure 10 Calculated surface settlement along C.L of metro tunnel based on different volume losses.
1. A 2-D numerical model is applicable to analyze and predict the detailed performance of the metro tunnel system-Line 3. 2. The results calculated by the proposed 2-D finite element model have a good agreement with the field data. The predicted surface settlements are underestimated by up 10% for Line 3 with respect to the field measurement. 3. The minimum width of the 2-D numerical model is set to be ten times the metro tunnel diameter. 4. Ground loss is an important parameter effect on the performance of the metro tunnel system.
Acknowledgement The authors acknowledge the National Authority for Tunnels (NAT) and the Egyptian Tunneling Society for the technical support. References Figure 11 Comparison between measured and calculated settlement of the Grater Cairo metro tunnel-Line 3.
Figure 12 Calculated vertical displacement at different levels along centerline of the metro tunnel-Line 3.
metro tunnel moves down due to the soil stress change. The soil stress change above the crown tunnel pushes soil to move downward. The soil under the invert of the metro tunnel heaves due to the soil stress change around tunnel excavation. The soil stress change beneath the tunnel invert pushes soil to move upward.
[1] El-Nahhass FM. Soft ground tunneling in Egypt. Geotechnical challenges and expectations. J Tunnel Underground Space Technol 1999;14(3):245–56. [2] Mazek SA, El-Tehawy EM. Impact of tunneling running side-byside to an existing tunnel on tunnel performance using non-linear analysis. In: Proceeding of the 7th ICCAE. Cairo, Egypt; 2008. [3] El-Nahhas FM. Spatial mode of ground subsidence above advancing shielded tunnels. In: Proceeding of international congress on large underground opening, Fireze, Italy, vol. 1; 1986.p. 720–5. [4] Bicel JO, Kuesel TR. Tunnel engineering hand book. New York, USA: Van Nostrand Reinhold Company; 1982. [5] Lee CJ, Chiang KH, Kuo CM. Ground movement and tunnel stability when tunneling in sandy ground. Proc J Chinese Inst Eng 2004;27(7):pp. 1021–1032. [6] Mazek SA, Law KT, Lau DT. Effect of grouting on soil reinforcing and tunnel deformation. In: International underground infrastructure research conference, Waterloo University, Kitchener, Canada; 2001a. [7] Abu-Krisha A. Settlement control of CWO Sewer tunnel during boring El-Azhar road tunnels in Cairo. In: Proceeding of the international world to congress Milano; 2001. p. 3–9. [8] Abu-Farsakh MY, Tumay MT, Fellow ASCE. Finite element analysis of ground response due to tunnel excavation in soils. In: Proceeding of the international journal for numerical and analytical methods in geomechanics engineering, AinShams University, Egypt, vol. 23; 1999. p. 524–5. [9] Darabi A, Ahangari Kaveh A, Noorzad A, Arab A. Subsidence estimation utilizing various approaches – a case study: Tehran No. 3 subway line. Tunnel Underground Space Technol 2012;31:117–27. [10] Elsayed A. Study of rock-lining interaction for circular tunnels using finite element analysis. Proc Jordan J Civ Eng 2011;5(1):50–64.
716 [11] Cavalaro SHP, Blom CBM, Walraven JC, Aguado A. 14Structure analysis of control deficiencies in segmented lining. Tunnel Underground Space Technol 2011;26, 651-127. [12] Kivi A Valizadeh, Sadaghiani MH, Ahmadi MM. Numerical modeling of ground settlement control large span underground metro station in Tehran metro using central beam column (CBC). Tunnel Underground Space Technol 2012;28:218–28. [13] Liu Jiangfeng, Qi Taiyue, Wu Zhanrui. Analysis of ground movement due to metro tunnel station driven with enlarging shield tunnels under building and its parameter sensitivity analysis. Tunnel Underground Space Technol 2012;28:287–96. [14] Wang Zhechao, Wong Ron CK, Li Shucai, Qiao Liping. Analysis of ground movement due to metro tunnel station driven with enlarging shield tunnels under building and its parameter sensitivity analysis. Tunnel Underground Space Technol 2012;30:85–92. [15] Wang Yu, Shi Jaingwei, Ng Charles. Numerical modeling of tunneling effect on buried pipelines. Can Geotech J 2011;48:1125–37. [16] Chehade FH, Shahrour I. Numerical analysis of the interaction between twin-tunnels: influence of the relative position and construction procedure. J Tunnel Underground Space Technol 2008;23:210–4. [17] Mazek SA, Law KT, Lau DT. 3-D Analysis on the performance of a grouted tunnel. Canadian geotechnical conference, Calgary, Canada, vol. 1. p. 111–9. [18] Mazek SA. Impact of grouting on an existing tunnel performance under passed by another tunnel. In: Proceeding of the 11th ICSGE, 17–19 May, Cairo, Egypt; 2005. [19] Vermeer PA, Moller SC. Numerical simulation of tunnel installation. J Tunnel Underground Space Technol 2008;23:461–75. [20] National Authority for Tunnels (NAT). Project Document; 2009. [21] Janbu N. Soil compressibility as determined by oedometer and triaxial tests. In: European conference on soil mechanics of foundation engineering, Wiesbaden, Germany, vol. 1; 1963. p. 19– 25. [22] Duncan JM, Chang CY. Nonlinear analysis of stress and strain in soils. J Soil Mech Found Div ASCE 1970;96(SM5), September. [23] Duncan JM, Byrne PM, Wong KS, Mabry P. Strength, stressstrain, and bulk modulus parameters for finite element analysis of stresses and movements in soil masses. University of California, Berkeley, CA. Report no. UCB/GT/80-01; 1980. [24] Byrne PM, Cheung H, Yan L. Soil parameters for deformation analysis of sand masses. Can Geotech J 1987;24:366–76. [25] COSMOS/M program. Structural research and analysis corporation, Los Angles, California, USA; 2005. [26] Chen WF, Mizuno E. Nonlinear analysis in soil mechanics. Netherlands: Elsevier Science Publishers B.V; 1990.
S.A. Mazek, H.A. Almannaei Dr. Sherif Abdel Aziz Mazek is an Associate Prof. of Civil Engineering Department, Military Technical College, Cairo, Egypt. He was born on October 7, 1968. He completed B.Sc. in Civil Engineering on July 1991. His Accumulated Evaluation was Excellent with Honor and final year evaluation was also Excellent. After graduation, he was worked as an Assistance Lecturer (1991–1998). He got a Egyptian scholarship from Faculty of Engineering, Carleton University, Ottawa, Canada (1999–2003) for Ph.D. Degree in Civil Engineering. His Affiliation was a faculty member at Military Technical College (2003–2010). He completed his M. Sc. on April 1997 (1993–1997). His M.Sc. Thesis Title was ‘‘Underpinning of tunnel and underground structure.’’ He got Faculty Graduation of M. Sc. in Military Technical College, Cairo, Egypt. He got Ph. D. on March 2003 (1999–2003). His Ph.D. Thesis Title was ‘‘Soil structure interaction modeling and analysis of tunnel structures.’’ And he got Faculty Graduation of Ph. D. in Faculty of Engineering, Carleton University, Ottawa, Canada. He joined as a Consultant Engineer on June 2007. He also finished a course, ‘‘Certification at Time Management,’’ from American University, Cairo. He teaches the following courses: (1) Reinforced Concrete, (2) Foundation Analysis and Design, (3) Tunnel and underground structure Engineering, (4) Finite element analysis, (5) Theory of structure. He supervised nine theses (two Ph.D. Theses and seven M.Sc. Theses). His scientific activities are as follows: (1) Member at Egyptian Society of Tunnels-Cairo-Egypt (Scientific Society), (2) Member at Intentional Society of Tunnels (Scientific Society), (3) Members at Egyptian Geotechnical Society (EGS), (4) Members at International Society of Soil Mechanics and Geotechnical Engineering (ISSMGE). He published 35 papers.
Eng. Hassan Abdul Wahab Almannai is a civil engineer at engineering department in Bahrain and at Ismail Khonji Associates (Consultant Engineers). He was born on December 26, 1984. He completed B.Sc. in Civil Engineering in July 2007 from Military Technical College, Cairo, Egypt. His accumulated evaluation was good and final year evaluation was also good. He completed his M.Sc. in civil engineering in September 2012 (2010– 2012). He also got M.Sc. from Military Technical College, Cairo, Egypt. His M.Sc. Thesis Title was ‘‘Modeling and analysis of underground reinforced concrete structure.
