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波浪循环荷载通过堤身和砂质土置换层传递给软土地基,在软土地基中产生循环动应力,使软黏土发生不排水强度弱化现象,严重影响格型钢板桩防波堤承载性能。结合工程算例,基于动力有限元法建立考虑软土循环弱化效应的格型钢板桩防波堤三维弹塑性动力分析模型,对软土地基在循环荷载作用下最大孔压增长规律以及不排水强度弱化特性进行研究。建立格型钢板桩-软土地基系统动力稳定性分析方法,对格型钢板桩-软土地基系统的破坏模式、稳定性以及沉降变形特性进行分析。结果表明:最大孔隙水压力主要分布在格体周围软土层,主、副格仓底部及部分桩-土接触部位的不排水强度发生明显弱化。考虑软土地基循环弱化效应时,格型钢板桩-软土地基系统的稳定性安全系数显著降低。建议在实际工程中应考虑软土地基循环弱化效应对格型钢板桩防波堤稳定性的影响。
Wave cyclic loads are transferred to the soft ground through the embankment and sandy soil replacement layer to generate cyclic dynamic stress in the soft soil so that the undrained strength of the soft clay is weakened and seriously affect the bearing capacity of the lattice sheet pile breakwaters. Based on the dynamic finite element method, a three-dimensional elastic-plastic dynamic analysis model of steel sheet pile breakwater considering the effect of soft soil circulation weakening is established based on the dynamic finite element method. The law of maximum pore pressure increase under cyclic loading and the weakening characteristics of undrained strength research. The analytical method of dynamic stability of grid-supported steel sheet pile-soft soil foundation system is established, and the failure mode, stability and settlement deformation characteristics of grid steel sheet pile-soft soil foundation system are analyzed. The results show that the maximum pore water pressure is mainly distributed in the soft soil layer around the cell body, and the undrained strength of the bottom and part of the pile-soil contact parts of the main and auxiliary cells is weakened obviously. Considering the weakening effect of the soft soil foundation, the safety factor of the stability of the lattice steel sheet pile-soft soil foundation system is significantly reduced. It is suggested that the effect of weakening of soft soil foundation on the stability of lattice steel sheet breakwater should be considered in practical engineering.