不同本构模型在开挖边坡有限元强度折减法中的应用

Application of Different Constitutive Models to Stability Analysis of Excavation Slope

通过不同模型计算所得的开挖边坡安全系数在理论上是一致和统一的,但是边坡特征点位移会由于计算采用的土体本构模型的不同而有很大差异.分别采用能反映真实开挖应力路径的剑桥系列弹塑性本构模型对开挖边坡开展有限元强度折减稳定性分析,然后与采用极限平衡法分析得到的结果进行比较.结果表明,采用不同模型计算得到的边坡稳定性安全系数具有统一性和一致性,但不同模型计算得到的边坡特征点位移不同.采用变形量失稳判据对开挖边坡开展有限元强度折减稳定性分析时必须采用能反映开挖应力路径的本构模型,这样才能结合现场变形观测有效预测开挖边坡工程的土体变形并有效评估开挖边坡的稳定性.

The safety factors of the excavation slopes calculated by different models are consistent and unified in theory.However,the displacement of characteristic points of slope is greatly different due to the different constitutive models of the soil used in the calculation.The stability analysis of excavated slope is carried out by the method of finite element strength reduction using the Cam-Clay elastoplastic constitutive models which can reflect the actual process of slope excavation,and the stability results obtained by the limit equilibrium method are compared with those results.The results show that the slope stability safety factors calculated by different models are unified and consistent,but the displacement of slope characteristic points calculated by different models is different.The constitutive model which can reflect the excavation stress path should be used in the FEM strength reduction stability analysis based on deformation instability criterion,which can make the prediction of the soil excavation deformation and the evaluation of stability of slope excavation more effectively by combining with field deformation observation.