- Volume 10 Issue 5
The present research presents experimental and finite element studies to investigate the behavior of piled raft-tunnel system in a sandy soil. In the experimental work, a small scale model was tested in a sand box with load applied vertically to the raft through a hydraulic jack. Five configurations of piles were tested in the laboratory. The effects of pile length (L), number of piles in the group and the clearance distance between pile tip and top of tunnel surface (H) on the load carrying capacity of the piled raft-tunnel system are investigated. The load sharing percent between piles and rafts are included in the load-settlement presentation. The experimental work on piled raft-tunnel system yielded that all piles in the group carry the same fraction of load. The load carrying capacity of the piled raft-tunnel model was increased with increasing (L) for variable (H) distances and decreased with increasing (H) for constant pile lengths. The total load carrying capacity of the piled raft-tunnel model decreases with decreasing number of piles in the group. The total load carrying capacity of the piles relative to the total applied load (piles share) increases with increasing (L) and the number of piles in the group. The increase in (L/H) ratio for variable (H) distance and number of piles leads to an increase in piles share. ANSYS finite element program is used to model and analyze the piled raft-tunnel system. A three dimensional analysis with elastoplastic soil model is carried out. The obtained results revealed that the finite element method and the experimental modeling are rationally agreed.
piled raft;tunnel;load test;piles share;finite element
- Abdullah, M.H. and Taha, M.R. (2013), "A review of the effects of tunneling on adjacent piles", Elctric. J. Geotech. Eng., 18, 2739-2762.
- ANSYS 12.1 (2010), ANSYS 12.1 Finite element analysis system help, SAS IP, Inc.
- ASTM D422-2001 (2001), Standard test method for particle size-analysis of soils.
- ASTM D4253-2000 (2000), Standard test method for maximum index density and unit weight of soils using a vibratory table.
- ASTM D4254-2000 (2000), Standard test method for minimum index density and unit weight of soils and calculation of relative density.
- ASTM D854-2005 (2005), Standard test method for specific gravity of soil solids by water pycnometer.
- Benton, L.J. and Phillips, A. (1991), "The behavior of two tunnels beneath a building on piled foundations", Proceedings of the 10th European Conference on Soil Mechanics and Foundation Engineering, Florence, Italy, May, pp. 665-668.
- Calabrese, M. and Monaco, P. (2001), "Analysis of stresses induced in an old deep tunnel by pile driving from the surface", Proceedings of the 2nd FLAC Symposium on Numerical Modeling in Geomechanics, Lyon, France, October, pp. 199-204.
- Cheng, C.Y., Dasari, G.R., Leung, C.F. and Chow, Y.K. (2002), "A novel FE technique to predict tunneling induced ground movement in clays", Proceedings of the 15th KKCNN Symposium on Civil Engineering, Singapore, October, pp. 43-48.
- Chore, H.S. and Siddiqui, M.J. (2013), "Analysis of the piled raft for three load patterns: A parametric study", Coupled Syst. Mech., Int. J., 2(3), 289-302. https://doi.org/10.12989/csm.2013.2.3.289
- Cox, W.R., Dixon, D.A. and Murphy, B.S. (1984), "Lateral-load tests on 25.4-mm (1-in.) diameter piles in very soft clay in side-by-side and in-line groups, laterally loaded deep foundations: Analysis and performance", ASTM STP 835, pp. 122-139.
- Fattah, M.Y., Yousif, M.A. and Al-Tameemi, S.M.K. (2015), "Effect of pile group geometry on bearing capacity of piled raft foundations", Struct. Eng. Mech., Int. J., 54(5), 829-853. https://doi.org/10.12989/sem.2015.54.5.829
- Huang, M., Zhang, C. and Li, Z. (2009), "A simplified analysis method for the influence of tunneling on grouped piles", Tunn. Undergr. Space Technol., 24(4), 410-422. https://doi.org/10.1016/j.tust.2008.11.005
- Lee, Y.J. and Bassett, R.H. (2007), "Influence zones for 2D pile-soil-tunneling interaction based on model test and numerical analysis", Tunn. Undergr. Space Technol., 22(3), 325-342. https://doi.org/10.1016/j.tust.2006.07.001
- Meguid, M.A. and Mattar, J. (2009), "Investigation of tunnel-soil-pile interaction in cohesive soils", J. Geotech. Geoenviron. Eng., ASCE, 135(7), 973-979. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000004
- Mokwa, R.L. (1999), "Investigation of the resistance of pile caps to lateral loading", Ph.D. Dissertations; Virginia Polytechnic Institute and State University, Blacksburg, VA, USA.
- Mroueh, H. and Shahrour, I. (2003), "A full 3-D finite element analysis of tunneling-adjacent structures interaction", Comput. Geotech., 30(3), 245-253. https://doi.org/10.1016/S0266-352X(02)00047-2
- Surjadinata, J., Hull, T.S., Carter, J.P. and Poulos, H.G. (2006), "Combined finite- and boundary-element analysis of the effects of tunneling on single piles", Int. J. Geomech., 6(5), 374-377. https://doi.org/10.1061/(ASCE)1532-3641(2006)6:5(374)