深基坑开挖全过程的数值模拟及工程实践

摘要

This paper is using both the Duncan-Chang hyperbolic model of non-linear elastic soil mechanics and the numerical method of analysis, to process in its contrast and research of the soil stress variation together with the consideration of surcharged loads added or ignored; investigating at the same the influence on the whole process of excavation due to the surcharges concerned. After studying a practical engineering case of deep pit excavation with surcharged loads introduced by adjacent constructions, it is mainly concluded that：under the action of surcharged loads,a ＂weak zone＂ with obviously reduced value of modulus of deformation appears in the area next to the loads,as the excavation is carried on,any small variation of loadings can bring substantial settlement of that zone, and a broad comprehension of such matter of its origin of stress variation and mechanism is reaching.%利用非线性弹性模型中的Duncan-Chang双曲线模型及数值分析方法，对比研究在开挖区外有和没有附加荷载的场地土在开挖全过程中的应力变化，探索这些荷载对开挖全过程的影响。通过模拟分析开挖区外有建筑物等附加荷载作用的深基坑开挖工程实例，得出了一个重要结论：在附加荷载作用下，土体会在靠近附加荷载侧边附近形成一个变形模量明显变小的‘软弱区’，随着开挖的进行，此处任何微小的荷载变化均可产生大量沉降，并揭示了在这些荷载作用下开挖全过程产生变化的原因和机理。