Research On The Ultimate Bearing Capacity And Failure Mode Of Soft Clay Foundation With Upper Hard Crust

Soft soil is widely distributed in coastal areas and inland plain areas in China, over which the hard crust layer is formed, with the long-term effect of evaporation of water, groundwater lowering, load moving and the deposition of soluble salts. Because of the special engineering quality of the hard crust layer, highway embankment has been directly built on it in some construction. However, its failure mode and ultimate bearing capacity under embankment still need to be studied further.Numerous relevant constructions and research results are analyzed. Based on a coastal highway construction, with the numerical analysis software of ABAQUS, the numerical models of various working conditions are established. The failure mode of soft soil foundation with upper hard crust is analyzed, based on which, the ultimate bearing capacity is studied, and a corrected formula is finally raised up, the major achievements and conclusions are as follows:1. Numerous relevant constructions and research results are summarized; current research status of the failure mode and the ultimate bearing capacity of soft soil foundation with upper hard crust are analyzed for further study.2. Based on practical construction and finite element method, with reasonable constitutive relation, parameters, boundary conditions and so on, the numerical model is established, which is validated by comparing with practical monitoring results.3. The special engineering qualities of the hard crust layer like stress dispersion effect and enclosing effect are studied, meanwhile how the failure mode and distribution of additional stress are affected by the elastic modulus ratio of hard crust layer and soft soil, the depth and cohesion of hard crust layer is also analyzed.4. Current ultimate bearing capacity of layered foundation soil theories are analyzed thoroughly, taking the special engineering qualities of the hard crust into account, a corrected formula is finally raised up, based on which, sensitivity analysis of factors which affect the ultimate bearing capacity is carried out.