本构模型与软黏土强度增长的关系研究

Research on correlation between soil model and shear strength gain in staged construction

已有的软黏土堆载固结强度增长计算方法虽然比较简单,但是无法考虑土的应力应变关系对其影响.从邓肯-张模型和魏汝龙-Khosla-Wu模型出发,建立了排水固结法加固软弱地基的强度增长计算公式.它不但与上覆荷重和有效内摩擦角有关,而且与有效内凝聚力、静止土压力系数、土的压缩模量和回弹模量等一系列本构模型参数有关.目前工程中应用的几个强度增长近似计算公式,仅考虑了上覆荷重和内摩擦角的影响,只能在一定的范围内与工程实际相符合.数值分析表明:当K0=0.5～1.0时,本文提出的强度增长公式与有效固结应力法提出的强度增长公式最大相差25%.

Some experiential methods to predict the shear strength gain during staged construction in soft ground are considerably simple since they do not take the soil stress-strain model into account. On the basis of Duncan-Chang model and Wei-Khosla-Wu model in the soft ground, a new formula for the strength gain in staged construction was established. This formula concerned the upper loading and a series of model parameters, such as the effective angle of internal friction, the effective cohesive intercept, the coefficient of earth pressure at rest K0, the modulus of compressibility, the modulus of resilience. Compared with the proposed formula, the former experiential formulae were only accurate in some conditions. The numerical analysis showed that the maximum discrepancy between the shear strength gain computed by the proposed formula and that computed by the effective consolidation stress formula was about 25% at K0=0.5-1.0.