基于修正摩尔库伦模型的深基坑变形数值分析

为了探究深基坑变形数值分析中模型参数的重要性,运用MIDAS-GTS/NX有限元分析软件,分别采用摩尔库伦模型(MC)、参考应力不变的修正摩尔库伦模型(MMC)以及参考应力随基坑深度变化的修正摩尔库伦模型(MMC),进行排桩支护变形和地表沉降的数值模拟,并与实际监测结果进行对比分析,结果表明:在地表沉降预测上,摩尔库伦模型(MC)预测沉降值与实测值相差较大,预测沉降影响距离是实测沉降影响距离的2倍左右;在排桩水平位移预测上,MC模型预测位移完全大于实测位移,且发生最大水平位移处排桩深度与实际深度不符;MMC模型预测值与实测值相差不大,且两者位移规律曲线较为吻合.因此不同参考应力下的MMC本构模型比单一参考应力下的MMC本构模型预测变形更加精确,故使用不同参考应力下的MMC本构模型进行基坑开挖变形预测更具参考价值.

Numerical Analysis of Deep Foundation Pit Deformation Based on Modified Mohr-Coulomb Model

To explore the importance of model parameters in deep foundation pit deformation numerical analysis, the finite element analysis software MIDAS GTS/NX, respectively, using Mohr coulomb model (MC), the correction of a constant reference stress Mohr coulomb model (MMC) and reference stress changing with depth of foundation pit of the modified Mohr coulomb model (MMC), for the numerical simulation of the pile supporting deformation and surface subsidence, and compared with the actual monitoring results analysis, the results show that:(1) In the prediction of surface settlement, there is a big difference between the predicted settlement value of The Moorcoulomb model (MC) and the measured settlement value, and the predicted settlement impact distance is about 2 times that of the measured settlement impact distance;(2) In terms of the horizontal displacement prediction of pile row, the predicted displacement of MC model is completely greater than the measured displacement, and the depth of pile row at the place where the maximum horizontal displacement occurs is inconsistent with the actual depth;(3) The predicted values of MMC model differ little from the measured values, and the displacement regularity curves of the two models are in good agreement.Therefore, the MMC constitutive model under different reference stresses is more accurate than the MMC constitutive model under single reference stresses in deformation prediction of foundation pit excavation.