地基承载力确定标准的研究

现行规范根据载荷试验确定地基承载力时所依据的是线性变形理论,存在着保守的倾向.<工程地质手册>中的经验公式表明基础沉降与基础宽度之间为非线性关系.对砂性土和粘性土地基进行的多工况变直径的非线性数值模拟计算与分析,结果表明,随着基础宽度B的增大,基础沉降s增大的趋势迅速平缓,相对沉降s/B最终将收敛于零,表现出显著的非线性.据此,按照变形控制,结合工程实例,对规范中s/b的取值规定,按荷载板面积提出了初步的修改建议,一般可将承载力特征值提高20%～40%.

Study of Standard in Determining Ground Bearing Capacity

In current codes, the basis according to which we determine the subgrade bearing capacity by plate loading test is linear deformation theory. There is a conservative trend. The empirical equation in project geology handbook 2nd has shown that the relationship between foundation deformation and foundation width is nonlinear. It simulates the plate loading test in sand and clay ground by nonlinear numerical analysis. The conclusion is found that foundation settlement s will increase with the foundation width B, and relative settlement s/B will be convergent to zero ultimately. It is a nonlinear relation. So according to the principle of deformation controlling, for the different areas of loading plates, some primary suggestions on value of s/b are given respectively. Commonly, characteristic value of subgrade bearing capacity can be enhanced by 20 - 40%.