大型储罐水泥粉煤灰碎石桩复合地基变形应力性状试验研究

EXPERIMENTAL RESEARCH ON DEFORMATION AND STRESS BEHAVIORS OF CFG PILE COMPOSITE FOUNDATION OF LARGE STORAGE TANK

以某大型储罐为依托工程,对其水泥粉煤灰桩(CFG桩)复合地基的变形应力性状进行试验研究。设置环墙沉降观测点,采用水管式沉降仪和孔隙水压力计等进行充水预压期间地基变形应力性状的原型观测和处理后地基的原位测试。通过现场试验,揭示了大型储罐柔性基础下CFG桩复合地基的变形应力性状:储罐地基沉降呈内大外小的碟形分布,在罐中心至0.5R范围内地基土沉降较大且变化幅度不大,0.5R至罐周范围的地基土沉降逐渐减小,环墙最小,CFG桩与桩间土的变形不符合等应变假定;超静孔隙水压力主要取决于土层性质特别是其渗透性和充水荷载引起的附加应力,孔隙水压力增长和消散的过程与充水荷载过程线相似,距罐中心(0.25~0.75)R范围内各测点超静孔隙水压力相差不大,环墙处最小,充水荷载作用下孔隙水压力的分布基本与储罐地基相应深度附加应力的分布规律一致。

Based on the project of a large storage tank,the deformation and stress behaviors of CFG pile composite foundation was studied by means of field tests.The experimental research on the deformation and stress behaviors of CFG pile composite foundation for large storage tank by means of on-site test and prototype observation with settlement measuring points in the ring wall,water pipe settlement gauges and pore water pressure gauges.The deformation and stress behaviors of CFG pile foundation of large storage tanks were revealed through field tests.It was revealed that the settlement distribution of foundation of storage tanks had the shape of the disc with large settlement inside and small one outside,and the settlement within the scope of 0.5R away from the center of foundation was large and had no great change through field tests.The deformation of the soil between piles and the deformation of CFG piles in the composite foundation did not obey the iso-strain assumption under the action of loads.The excess pore water pressure mainly was related to the physical properties of soil and the additional stress caused by the water-filled load.The process of pore water pressure growth and dissipation was similar to that of the process of water filling,and the excess pore water pressure at each measuring point had no great difference and that of the ring wall was the smallest.The distribution of the excess pore water pressure was consistent with that of the additional stress at the corresponding depth.