The Raft Foundation Settlement Analysis In Condition Of Goaf Residual Deformation

With the rapid development of infrastructure in China, large-scale buildings in someareas have to pass through or to be built above the goaf in some areas. Under the effect ofthe building loads, some goafs which should have been in a relatively balanced state arelikely to be "activated” again, causing the surface to generate additional movement anddeformation, and thus threatening the stability and security of the building foundation andoverall structure. Raft foundation could improve the integrity of foundation and enhancethe capability of the structure to resist deformation, and it is widely used in the mined-outarea. Therefore, to carry out research on interaction between goaf raft and foundation soilhas an extremely important theoretical and practical value.With the methods of theoretical deduction and numerical simulation, the paper carriesout research on internal forces and deformation of the old mining buildings raft foundationabove the empty areas. The main work is as follows:(1) Based on the analysis of goaf residual principle on old mining surface, the goafresidual settlement model is established and guided by the key layer theory on goaf thetheory also combines elastic plate theory.(2) Applying the thin plate theory and based on the principle of minimum potentialenergy and analysis of the composition of the characteristics of the analytical solution, thepaper regards raft foundation as free sheets on the four edges of the elastic foundation andsimplify the original deflection formula, thus getting the simple solution that is moresuitable in engineering application and promotion.(3) The paper establishes the overall finite element model of old buildings above thegoaf, analyzes of frame structures under different circumstances the raft of internal forcesand deformation and finds that raft internal force and settlement are mainly affected by thesurface curvature, raft stiffness and rigidity of the upper structure.