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上海第4层黏土是典型的结构性海相软土,用一个本构模型统一地模拟不同应力路径下的力学特性对数值计算具有重要意义。对UNIFIED模型的结构性及超固结发展函数进行了改进,并提出了一种确定原状土材料参数和初始状态的方法。为了验证修正模型的正确性,用块状取土法取得上海第4层原状土样,进行了固结试验和三轴排水、不排水剪切试验。通过比较试验结果和本构模拟结果,明确了新的本构模型仅用一组材料参数就能统一地模拟上海第4层黏土在固结、排水及不排水三轴试验得到的应力-应变关系。模拟结果揭示了上海第4层黏土的结构比较稳定,即使在经历三轴剪切发生35%轴应变后仍能保持较高位的结构性。
The 4th clay in Shanghai is a typical structural marine soft clay. It is of great importance to use a constitutive model to simulate the mechanical properties under different stress paths in a unified way. The structural and overconsolidated development function of the UNIFIED model is improved and a method of determining the parameters and initial state of undisturbed soil material is proposed. In order to verify the correctness of the correction model, the fourth soil sample in Shanghai was obtained by using block soil acquisition method. The consolidation test, triaxial drainage and undrained shear tests were carried out. By comparing the experimental results with the results of the constitutive simulation, it is clear that the new constitutive model can simulate the stress-strain relationship of the clay of the fourth layer in Shanghai with consolidation, drainage and undrained triaxial tests using only one set of material parameters . The simulation results reveal that the structure of clay in Shanghai No.4 clay layer is relatively stable, even though its structure is relatively high even after 35% axial strain under triaxial shear.