小应变条件下隧道开挖引起的横向沉降槽分析

利用配备有局部高精度位移传感器STDTTS+UNSAT型号的高级应力路径三轴测试系统，对小应变条件下的土体进行了试验。采用三维数值分析方法和应用小应变模型及摩尔-库仑模型，分别对隧道施工引起横向沉降槽的影响展开了研究。结果表明，在小应变条件下土体表现出高模量以及模量随应变增加而衰减的特性，且当剪切应变应用对数坐标（lg）表示时，剪切模量随剪切应变增加而衰减的规律可以表示为带有2个拐点的反S型曲线，同时，利用式（1）对其进行很好地模拟；两类模型计算结果的规律性是相似的，采用小应变模型所得到的最大下沉位移符合工程实际，且横向沉降槽的宽度也能符合现场实测，即能够适当地解决采用一般模型所得到的最大下沉位移合理，而横向沉降槽的宽度过宽，或者横向沉降槽宽度合理，而最大下沉位移过小，两者间存在对立的问题。通过计算结果对比进一步验证了考虑小应变条件下土体特性的必要性以及二次开发所得到的模型的合理性与可适用性。

Analysis of tunneling-induced traverse settler under small strain

The soil properties under small strain are tested through advanced stress path triaxial test system (STDTTS+UNSAT) equipped with high precision local displacement tensor. Using three dimensional numerical simulations, the influence of tunneling on traverse settler was studied by the models of small strain and Mohr-Coulomb separately. Some conclusions are drawn. Firstly, there is high modulus of soil under small strain and modulus degrades with the increase of strain. When logarithm coordinates are applied to describe shear strain, the rule of shear modulus decaying with shear strain can be expressed by reversed S-shaped curve with two inflexion points; and the function of the curve is deduced. Secondly, rules of the results by both models are similar. Finally, both the maximum subsidence displacement and the width of traverse settler by using small strain model are accorded with practical project. While there is an incompatible problem by using the common models, that is, only the maximum subsidence displacement or the width of traverse settler is reasonable. The comparative analysis is made to validate the indispensability of small strain consideration, as well as the reasonability and feasibility of the second development model.