碎石桩复合地基抗液化性能的数值模拟

NUMERICAL SIMULATION OF ANTI-LIQUEFACTION CHARACTERISTIC OF STONE COLUMNS COMPOSITE FOUNDATION

将饱和砂土视为土-水两相介质,以Biot动力固结方程为基础,编制完全耦合的三维排水有效应力动力反应分析程序,通过模型试验验证程序的正确性。利用该程序对碎石桩复合地基进行地震响应分析,探讨不同土层构成和不同附加压重等因素对抗液化性能的影响。结果表明:经碎石桩加固后,桩间土中的超孔压比比未加固前减小;随时间的延长,出现了明显的超孔压消散现象,距离碎石桩越近,超孔压消散现象越明显;附加压重对地基中超孔隙水压力的增长有明显地抑制作用,在进行工程设计时应该考虑附加压重的有利影响,适当增加桩间距。

Saturated sand is looked as soil-water two-medium, the fully coupled three-dimension effective-stress dynamic analysis procedure is developed on the base of Biot dynamic theory and the right of procedure was proved. Stone columns composite foundation is analyzed by the developed procedure, the influence of different soil layer and different additive pressure on anti-liquefaction characteristic of composite foundation is discussed. The research shows that the excess pore water press ratio in the soil around column is smaller than that of reinforcement before. With decreasing of input earthquake acceleration, the dissipation of.excess pore water press is remarkable, the distance from stone columns is smaller, and the dissipation is more remarkable. Additive pressure can restrain the incensement of excess pore water pressure, this favourable factor should be considered in engineering design and the space of stone columns may be increscent.