饱和软黏土循环累积孔压模型及地铁隧道路基长期沉降计算

不同围压和固结方式下,在进行上海地区第4层饱和软黏土不排水循环三轴试验及累积孔压影响因素分析基础上,引入修正动偏应力水平,建立循环累积孔压显式模型;并利用循环三轴试验结果验证模型合理性。提出交通荷载作用下软土地基长期运营沉降分析方法,并应用于上海地铁隧道路基长期沉降预测。该方法采用拟静力有限元计算循环累积塑性变形和孔压显式模型相结合的方式,所需计算参数易于确定;对其他循环荷载作用下软土地基长期沉降预测有借鉴作用。

Cyclic Accumulative Pore Pressure Explicit Model of Saturated Soft Clay and Long-term Settlement Calculation of Subway Tunnel Roadbed

A series of undrained cyclic triaxial loading tests of the 4th saturated soft clay stratum in the Shanghai area were performed under the confining and consolidation pressure,and the factors affecting the accumulative pore pressure were analyzed.On this basis,introducing in the revised dynamic deviatoric stress level,the cyclic accumulative pore pressure explicit model was established.The validity of the model was verified with the undrained cyclic tri-axial test results.A practical method was proposed to calculate the long term settlements of soft roadbed subject to traffic loading,which was applied in predicting the long-term settlements of soft soil tunnel roadbed of the shanghai Metro lines.By utilizing the pseudo-static finite element method to calculate the cyclic accumulative plastic strain explicit model and cyclic accumulative pore pressure explicit model in combination,the calculation parameters required by the proposed method were easy to be obtained.The method provides reference to long-term settlement prediction of soft soil roadbed subject to other cyclic loading.