天津滨海新区软黏土的蠕变特性及无屈服面模型研究

天津滨海新区大部分为围海造陆形成的陆域,主要为吹填土经真空预压加固的软黏土地基,具有鲜明的地域特征。其蠕变特性对该地区的建筑物和构筑物地基的变形和长期稳定性有很大影响。采用大直径原状试样进行了三轴不固结不排水蠕变试验,研究了滨海新区软黏土的蠕变变形的规律性。在此基础上建立天津滨海新区软黏土的无屈服面蠕变模型,该模型只有5个参数,各参数物理意义明确,且可以通过试验确定。采用建立的模型对试验结果进行对比分析,理论模型计算结果与试验数据的拟合曲线吻合较好。该模型可用来对软黏土地基上结构物的长期蠕变变形的发展趋势和地基稳定性进行预测。

Study of creep properties of soft clay in Tianjin Binhai New Area and no-yield-surface constitutive model

Most parts of the Tianjin Binhai New Areas consist of lands formed by reclamation. The foundation soil is hydraulically filled materials and strengthened by vacuum preloading technique. Therefore, the soil in this region has some unique properties, such as the creep characteristics, which has great influences on the long term displacement and stability of the soil foundations of upper structures. The creep properties of undisturbed soil samples taken from construction sites in this area are tested under unconsolidated and undrained triaxial conditions. Based on the test data, a no-yield-surface constitutive model is established, which can simulate the creep properties of foundation soils in the Tianjin Binhai New Areas. The model contains five parameters that have definite physical meanings and can be determined with the test data. The predicted results with the established model agree well with the observed data through the tests. The numerical model can be used to estimate the long term displacements and stability of the soil foundations of existing structures.