Study On The Bearing Capacity Of Foundation In Karst Areas Based On The Finite Element Upper Bound Limit Analysis

Karst landforms are widely distributed in the central and western China, with therapid advance of the Western Development Strategy and the process of urbanization,infrastructure and industrial buildings construction boom underway. Currently urbanand rural construction land shortages have become increasingly prominent, it becomesvery difficult to avoid Karst sites in Karst areas. Numerous engineering practicalexperiences show that the underlying Karst cavities foundation, if properly treated,can be used as building foundation. Before the Karst ground treatment programsdeveloped, the evaluation of capacity and stability of foundation in Karst areas isneeded; Because there are so many factors affecting the bearing capacity in Karstregion that the analysis and evaluation work is particularly complex. For the timebeing methods for evaluating the bearing capacity and stability of the underlying voidfoundation still rely on qualitative analysis and engineering experience, andquantitative evaluation is still in the exploratory stage so far. Methods for determiningthe bearing capacity of Karst foundation is deficient. It is of economic significanceand great application value in the engineering practice to carry out further research onthe bearing capacity and stability of Karst areas foundation and influencing factors, aswell as to provide guidance for the selection of building and the treatment programs.Faced with the lack of calculation methods on the bearing capacity of foundationwith underground void in Karst areas, the upper bound finite element limit analysiswas performance in this paper to study the problem of the bearing capacity offoundation with underground void in Karst area. Firstly, the basic plastic limitprinciples theories and assume, and classic upper lower bound limit theorems waselaborated, based on this, the upper bound finite element limit analysis is presentedin detail, including: discrete units,mathematical programming models establishment,optimization solving for programming models. Secondly, based on the upper boundfinite element limit analysis, the method of bearing capacity calculation in the Karstarea is promoted, the numerical method can take the effect of multiple factors intoconsideration, Numerical examples analysis show that the method is feasible and theresults is reasonable. Then, parameters H/B, D/B and φ and other factors influencedon the ultimate bearing capacity and the corresponding failure modes relying on theexamples discussed, three typical foundation failure mode including underground voids was given. Further, the chart of bearing capacity coefficients about soilcohesion, surface overloading and soil weight is calculated by use the upper boundfinite element limit analysis. Finally, the parameter H/B, D/B and φ influence on eachbearing capacity coefficients was analyzed.