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为了研究灌注桩套管振动贯入引起的施工效应,通过物理模型试验,对套管贯入过程及贯入过程中孔隙水压力、水平向挤土应力和土塞闭塞程度的变化规律进行了分析;建立了能够有效模拟灌注桩套管振动贯入过程的数值分析模型,并对物理模型试验进行大变形数值模拟及对比.研究结果表明:灌注桩套管贯入深度每增加0.2 m,超孔隙水压力和水平向挤土应力分别增加1 k Pa和8 k Pa,但挤土效应的影响范围主要集中在距离套管中心半径为6倍管径的范围内;由于套管壁与土体的反复剪切,产生不完全闭塞的土塞,套管端部形成环形土拱,此段土塞承担了80%的内摩阻力;随着套管直径增大,土塞闭塞程度由不完全闭塞过渡到完全非闭塞状态;套管贯入相同深度时,饱和砂土地基中土塞高度为干砂地基中土塞高度的1.2倍.
In order to study the construction effect caused by the vibration penetration of cast-in-place bored pile casing, the variation regularity of pore water pressure, horizontal soil compaction stress and soil plug occlusion during the process of casing penetration and penetration was analyzed by physical model test A numerical analysis model was established to simulate the penetration process of bored cast-in-place bushing effectively. The numerical simulation and comparison of large deformation of physical model test were carried out. The results show that for every 0.2 m increase in bored pile penetration depth, Water stress and horizontal squeezing soil stress increased by 1 kPa and 8 kPa, respectively, but the influence range of squeezing effect is mainly concentrated in the range of 6 times the radius of the center of the casing; due to the casing wall and the soil Repeated shear, resulting in incomplete occlusion of soil plug, the casing end of the formation of annular soil arches, this section of soil borne 80% of the internal friction resistance; With casing diameter, soil plug the degree of occlusion by incomplete occlusion Transition to a completely non-occluded state; when the casing penetrates into the same depth, the height of the soil plug in the saturated sand foundation is 1.2 times the height of the earth plug in the dry sand ground.