【摘要】 为优化复合桩(即水泥土桩与碎石桩组合)加固液化土地基,通过水泥土长桩与碎石短桩、碎石长桩与水泥土短桩及水泥土长短桩复合加固液化土进行振动台试验,分析了不同加固模型超静孔隙水压力和孔压比的变化规律,记录土体表面的高度变化,揭示多元复合桩加固液化土的机理。结果显示:碎石桩在振动过程中是主要的排水渠道,其中碎石长桩与水泥土短桩复合加固液化土不同埋深处超静孔隙水压力值曲线变化不大,峰值均在4.8 kPa左右,试验结束时均在3.5 kPa左右,说明碎石长桩可以排深层水;水泥土长桩与碎石短桩复合加固液化土中浅层的超静孔隙水压力曲线基本重合,峰值在5 kPa左右,结束时在2.5 kPa,说明碎石短桩主要排中浅层水;水泥土长短桩复合加固液化土浅层土的孔压比峰值为0.7,说明其抗液化效果主要体现在浅层地基,其主要起到对土体"隔栅"分隔、抑制震陷的作用。本研究结果可为今后实际工程加固液化土提供参考和依据。更多还原

【Abstract】 In order to optimize the composite pile(cement pile and gravel pile) to reinforce liquescent sand foundation,the shaking table tests of liquescent sand foundation reinforced by long cement pile and short gravel pile,long gravel pile and short cement pile,and long-short cement pile were conducted.The variation of the excess pore water pressure and the pore water pressure of different liquescent sand foundation models reinforced by multiple composite piles were analyzed,and the height change of soil surface was recorded to reveal the reinforced mechanism of the liquescent sand foundation reinforced by multiple composite piles.The test results show that the gravel pile is the main drainage channel in the process of vibration.The peak of the excess pore water pressure at different depth of long gravel pile and short cement pile is around 4.8 kPa,and when the test is over,the value is aroud 3.5 kPa,meaning that the long gravel pile can drain away deep water.The excess pore water pressure curves in the middle and low depth of the liquescent sand foundation reinforced by long cement pile and short gravel pile coincide basically.The peak of excess pore water pressure in different depth of long cement pile and short gravel pile is around 5 kPa and when the test is over,the value is aroud 2.5 kPa,meaning that the short gravel pile mainly drains away shallow water.The peak of pore water pressure in low depth of long-short cement pile is 0.7.The effect of the liquescent sand foundation reinforced by long-short cement pile mainly embodies in the shallow foundation and functions to separate soil-like barrier and restrain earthquake subsidence.This research may serve asa reference for liquefied soil reinforcement of practical engineering in the future.更多还原