与扁宽地梁组合的墩式基础的设计和分析

通过比较墩式基础和一般独立刚性基础与挖孔扩底桩的力学性质，分析与扁宽地梁组合的墩式基础的工作机理、地基破坏模式和承载力等问题，讨论持力层土质、墩底直径、墩基埋深和土的密实度对地基承载力提高系数的影响，得到了墩式基础比同样条件的挖孔桩承载力大的结论，求得了墩式基础和人工挖孔桩基础的地基承载力提高系数的经验公式。同时，从人工挖孔桩基础和墩式基础的地基承载力提高系数的对比中还发现，按现行规范设计相对埋深较小的挖孔桩时，其单桩承载力偏大，这在实际工程中是偏于不安全的。

DESIGN AND ANALYSIS OF BELLED PIER FOUNDATION COMBINED WITH FLAT AND WIDE GRADE BEAMS

By comparing the mechanical properties of pier foundation with those of normal non-reinforced spread foundation and cast-in-situ pile with hand excavation, the working mechanism, ground failure mode, and bearing capacity about pier foundation combined with flat and wide grade beams are analyzed. The influence of soil groups of sustaining layer, bottom diameter of pier foundation, relative embedment depth and soil compactness on the increase coefficients of subgrade beating capacity in pier foundation are discussed. Then, the conclusion in which the bearing capacity of pier foundation is higher than that of cast-in-situ pile with hand excavation is achieved, and the empirical formulas for increase coefficients of subgrade bearing capacity in pier foundation and cast-in-situ pile with hand excavation are presented. It is also found that designing cast-in-situ pile with hand excavation with the smaller relative embedment depth according to the code, which is being used, will lead to a relatively larger calculation result. This will be danger in engineering application.