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研究目的:通过对上海虹桥综合交通枢纽虹桥高速铁路站区路基先张法预应力管桩沉桩施工过程中孔隙水压力变化、深层土体位移及桩顶标高的的监测,掌握沉桩过程对预应力管桩桩周土体的挤土效应,研究和采取有效降低挤土效应的具体措施,控制和降低沉桩过程对周围土体结构的影响程度。研究结论:监测发现,距打桩施工区的水平距离越近,受挤土效应的影响越大,超孔隙水压力累计增长量越大;深度越深,超孔隙水压力累计增长量越大。通过对超孔隙水压力及深层土体位移的监测,合理调整了桩基施工的速率和施工工序。管桩的挤土效应比较明显,位移主方向是打桩前进的相反方向。采取提前偏移措施投放桩位,可以减少打桩施工对已完成桩位的影响。在需要控制土体位移量的区域,严格控制打桩速度和打桩方向,同时采取跳打工艺,可以有效降低打桩的挤土效应。
Research purposes: Through the monitoring of the change of pore water pressure, the displacement of deep soil mass and the elevation of pile top during the construction of prestressed prestressed pipe pile in Shanghai Hongqiao High-speed Railway Station subgrade, grasp the process of pile sinking Study on the soil squeezing effect around the prestressed pipe pile and its concrete measures to effectively reduce the effect of squeezing soil to control and reduce the impact of pile driving on the surrounding soil structure. Research conclusions: The monitoring shows that the closer the horizontal distance from the piling construction area, the greater the effect of squeezed soil effect, the greater the cumulative increase of excess pore water pressure; the deeper the depth, the greater the cumulative increase of excess pore water pressure. By monitoring the displacement of excess pore water and deep soil mass, the rate of pile foundation construction and construction procedure are reasonably adjusted. Pipe pile squeeze effect is obvious, the main direction of displacement is the opposite direction of piling forward. Taking offsetting measures to put pile positions can reduce the impact of piling construction on the completed pile positions. In the area where soil displacement needs to be controlled, the piling speed and piling direction should be strictly controlled, and the hopping process should be adopted at the same time, which can effectively reduce the squeezing effect of piling.