洞庭湖区防洪堤坝地震液化判别及加固措施

Seismic liquefaction discrimination and reinforcement treatment of flood control dyke in Dongting Lake area

以洞庭湖区义合金鸡垸的防洪堤坝作为研究背景,利用ABAQUS软件对该防洪堤坝进行动静力分析,为了保证分析计算的准确与效率,对静力计算和动力计算采用不同的土体本构模型,静力计算选用Duncan-Chang模型,动力计算则采用等效黏弹性模型。基于抗液化剪应力法,再结合有限元计算的结果,对湖区堤坝地基的液化情况做出判别。并提出采用表面压重的加固措施,选取不同厚度计算验证,最后确定压重厚度为3.5m时,满足工程安全要求;静力作用下,防洪堤坝应力分布合理,加固后没有造成过大的沉降,而水压力引起的拉应力区域明显减少,向背水方向的水平位移也减小了一半;对加固前后应变较大的几个单元做出液化判别,结果表明,加固后堤坝地基在地震作用下不再发生液化现象。

Taking a section of flood control dam of Yihejinji polder land in Dongting Lake area as the research background,this paper carries out dynamic and static analysis of the flood control dam by ABAQUS software.In order to ensure the accuracy and efficiency of the analysis and calculation,different soil constitutive models are used for static calculation and dynamic calculation.The Duncan-Chang model is used for the former,and the equivalent linear viscoelastic model for the latter.Based on the anti-liquefaction shear stress method and the results of finite element calculation,this paper makes a judgment on the liquefaction of the dam foundation in the lake area.The reinforcement measures of surface cover weight are proposed,and different thicknesses are selected for calculation and verification.Finally,when the cover weight thickness is 3.5 m,the project safety requirements are met.Under the action of static force,the stress distribution of flood control dam is reasonable,and no excessive settlement is caused after reinforcement,while the tensile stress area caused by water pressure is obviously reduced,and the horizontal displacement to the backwater direction is also reduced by half.The liquefaction discrimination of several units with large strain before and after reinforcement is made.The results show that after reinforcement,the liquefaction of the dam foundation no longer occurs under the action of earthquake.