Stress and deformation due to embankment widening with different treatment techniques

Abstract

A two-dimensional (2-D) finite element (FE) model was developed to analyze the deformation and stress of embankment on soft ground due to widening with different treatment techniques. It is found that the embankment widening induces transverse gradient change due to differential settlements and horizontal outward movements at the shoulder of the existing embankment. Embankment widening also increases the shear stress along the slope of the existing embankment, especially at the foot of slope. The failure potential due to embankment widening may increase with the increase of widening width when the widening width is smaller than 8.5 m, but may decrease with the increase of widening width as the widening width is greater than 8.5 m. The effectiveness of four ground and embankment treatment techniques, including geosynthetic reinforcement, light-weight embankment, deep mixed columns, and separating wall were compared. The results indicate that these treatments reduce the differential settlements and improve the stability. The light-weight embankment has the most effectiveness among four treatments. By using the fly-ash backfill material in widening, the transverse gradient change decreases from 0.5%–1.3% to 0.26%–0.8% and the maximum horizontal displacement decreases from 2.76 cm to 1.44 cm.

Keywords

finite element model / ground treatment / road widening / geosynthetic reinforcement / light-weight embankment / deep mixed columns / separating wall

References

[1] LudlowS. J., ChenW. F., BourdeauP. L., LovellP. L.Embankment widening and grade raising on soft foundation soils. Phase 2, Research project final report: joint highway research project [R], 1993, West Lafayette, Purdue University

[2] VOS E, COUVREUR J F, VERMAUT M. Comparison of numerical analysis with field data of a road widening project on peaty soil [C]// Proceeding of International Workshop: Advances in Understanding and Modeling the Mechanical Behavior of Peat. Balkema, Rotterdam, 1994: 267–274.

[3] WANG Hao, HUANG Xiao-ming. Centrifuge model test and numerical analysis of embankment widening on soft ground [C]// Proc Applications of Advanced Technologies in Trans Eng of the 8th International Conf. ASCE T&DI, Beijing, China, 2004: 548–553.

[4] HAN Jie, HUANG Jie, LIU Song-yu, HONG Zhen-shun. Stresses and deformations induced by widening of existing embankments over soft soils [C]// Proceedings of the International Symposium of Lowland Technology. Saga, Japan, 2006: 201–205.

[5] LING Jian-ming, QIAN Jin-song, HUANG Qin-long. Failure mechanism and design criterion for low-volume roads subgrade widening [R]. Transportation Research Record 1989, TRB, National Research Council, Washington, D.C., 2007: 135–141.

[6] DeschampsR. J., HynesC. S., BourdeauP.Embankment widening design guidelines and construction procedures [R], 1999, West Lafayette, Purdue University

[7] HAN J, AKINS K. Case Studies of geogrid-reinforced and pile-supported earth structures on weak foundation soils [C]// O’NEILL M W, TOWSEND F C. Proceedings of the International Deep Foundation Congress, Geotechnical Special Publication No. 116, Deep Foundations 2002. Orlando (USA), ASCE, 2002: 668–679.

[8] van MEURS A, van den BERG A, VENMANS A A M, ZWABENBURG C. Embankment widening with the gap-method [C]// Proceedings of the 12th European Conference on Soil Mechanics and Geotechnical Engineering. Amsterdam, Netherlands, 1999: 1133–1138.

[9] ALLERSMA H G B, RAVENSWAAY L, VOS E. Investigation of road widening on soft soils using a small centrifuge [J]. Journal of Transportation Research Record, 1994(1462): 47–53.

[10] FORSMAN J, UOTINEN V. Synthetic reinforcement in the widening of a road embankment on soft foundation [C]// Geotechnical Engineering for Transportation Infrastructure. Balkema, Rotterdam, 1999: 1489–1496.

[11] HuangX.-m., WangHao.. Comparison between responses of reinforced and unreinforced embankments due to road widening [J]. Journal of Central South University of Technology, 2009, 16(5): 857-864

[12] HanJ., OztoprakS., ParsonsR. L., HuangJ.. Numerical analysis of foundation columns to support widening of embankments [J]. Computers and Geotechnics, 2007, 34: 435-448

[13] KRAHN J. Stress and deformation modeling with SIGMA/W [R]. GEO-SLOPE International, 2004.

[14] DuncanJ. M., ChangC.. Nonlinear analysis of stress and strain in soils [J]. Journal of the Soil Mechanics and Foundations Division, 1970, 96(5): 1629-1653

[15] ChenX.-b., ZhangJ.-s., AnG.-feng.. Test study of red stone granular soil’s rheological property in road embankment engineering [J]. Journal of Central South University of Technology: Science and Technology, 2007, 38(1): 154-159

[16] DendJ., BianLi.. Response and energy dissipation of rock under stochastic stress waves [J]. Journal of Central South University of Technology, 2007, 14(1): 111-114

[17] XuZ.-z., SuChao.. The design of ground treatment on the joint of Hu-ning and Xi-cheng expressway [J]. Advances in Science and Technology of Water Resources, 1998, 18(2): 49-51

[18] LiuH. L., CharlesW. W. N. G., FeiK.. Performance of a geogrid-reinforced and pile-supported highway embankment over soft clay: Case study [J]. Journal of Geotechnical and Geo-environmental Engineering, 2007, 133(12): 1483-1493

[19] GuoZ.-bian.The design and settlement analysis of the joint embankment on soft soil [D], 1999, Nanjing, Transportation College of HoHai University

[20] XuY., XieK.-h., LuT.-hao.. Consolidation analysis of composite ground with lime-fly ash columns by 3D FEM [J]. Chinese Journal of Geotechnical Engineering, 2002, 24(2): 254-256

[21] WangZ.-l., YinZ.-z., LiY.-chi.. Practical method for FEM analysis of embankment settlement with Duncan-Chang model [J]. Rock Science and Mechanics, 2005, 26(7): 1085-1089