软土蠕变固结特性研究

通过大量对比试验系统研究了广东典型软土的蠕变固结特性和计算模型。试验结果表明：软土的固结和次固结在变形中所占比例和发生受多种因素影响，包括初始荷载、加荷比、土体固结度、含水率、孔隙比；次固结系数与土体的应力历史、当前固结状态及加荷比有关，在预压荷载下会明显减小；次固结系数与压缩指数之比一般为常数，其值在0.025?0.10之间；剪切蠕变特性与土体所承受的固结压力有关，土样蠕变规律呈应变硬化特征；三轴蠕变特性与排水条件关系密切，固结作用可以削弱蠕变效应；同等加荷条件下，偏应力-轴向应变关系在排水剪切中呈线性关系。而在不排水剪切中呈非线性，并有明显的屈服特征；不排水剪切条件下持续加荷的加荷方式可以适当提高不排水强度。根据上述试验成果分别从考虑非线性本构关系和考虑排水条件分析了蠕变固结模型的建立路径。

Research on creep and consolidation characteristics of soft soil

Based on the mass of contrast tests, creep consolidation characteristics and calculating models of typical soft soil from Guangdong are systematically studied. The test results show that the deformation proportion of consolidation and secondary consolidation is related to the factors including initial load and loading ration in test, consolidation degree, water content and void ratio of soil samples. The complications of affecting secondary consolidation coefficient are loading history, loading ration and current consolidation state of soft soil. Preloading can reduce secondary consolidation coefficient. The scale between second consolidation coefficient and compression index is constant, about 0.025-0.10. Direct shear-creep characteristic is related to vertical consolidation pressure; and the creep rule presents strain hardening characteristics. Consolidation action can play down the creep effect, so the creep characteristic in triaxial test is connected with drainage condition. In coordination loading addition, the relationship between deviator stress and axial strain is nearly straight-line in CD test; but in CU test, it assumes nonlinear and there is visible yield characteristics. When the continuous loading manner is adopted in UU test, the failure strength will be improved. Bases of above results, the models of creep and consolidation are analyzed considering respectively nonlinear constitutive relationship and shear drainage condition.