割线模量法在沉降计算中存在的问题及改进探讨

Study on some problems of settlement calculation with secant modulus method and its modification

割线模量法是近几年获得青睐的计算地基沉降的新方法。分析了割线模量法与e—p 曲线法在沉降计算中产生差异的原因,主要在于定义应变的参考构形跟自重应力状态不同,以及压缩应变与压力呈双曲线关系的假定两个因素。提出一修正系数用以改进割线模量法的计算结果。针对8 个试验土样,得到修正系数随埋深逐渐减小的变化规律。结合某工程,探讨了e—p 曲线法、割线模量法和改进法的沉降计算值的差别及原因。对于符合双曲线模型的地基土体,改进的割线模量法不仅便于电算,还能提高计算精度,值得推广。

Secant modulus method (SMM) is a new method to calculate foundation settlement in recent years. The reasons responsible for distinct difference between predicted settlements with SMM and e-p curve method are analyzed, which are due to the fact that the reference configuration defining strain differs from the equilibrium state of self-weight stress, and that the relation of compression strain to pressure is assumed to be a hyperbolic curve. A new compensation factor is put forward to correct the results predicted by SMM. According to oedometer test results of eight soil samples, the compensation factor is found to decrease with increasing depth. Through a case study, the results obtained with e-p curve method, SMM and modified SMM are contrasted in detail and the reasons responsible for the difference are explored. For soils in accordance with hyperbolic model, the presented modified SMM is not only convenient for computer-aided analysis, but can also improve accuracy.