深基坑微扰动成桩及紧邻高铁站房变形特性研究

Investigation of micro disturbance pile construction technique and deformation characteristics of adjacent high-speed railway station buildings

开展现场试验和考虑土体刚度小应变特性的三维数值模拟,研究了海安高铁站房扩建基坑卸荷对紧邻桩基础房屋的影响。结果表明:围护结构MJS工法桩施工引起的紧邻桩基位移小于0.25 mm。MJS工法桩和多支撑联合作用下,基坑围护结构最大侧向变形为(0.045%~0.11%)H(H为开挖深度)。站房桩基嵌入粉砂层中,基坑施工引起的桩基水平位移明显高于上部建筑沉降。高铁站房—基坑的水平净距增至1.5H(H为最终开挖深度)后,桩基水平位移接近于0,表明基坑施工对高铁站房的影响区域为1.5H。围护结构厚度从0.30 m增至0.63 m后,桩基最大水平位移降低了68.7%;继续增加围护结构厚度,桩基水平位移降幅不明显。基坑开挖宽度从0.83H增至2.0H时,桩基最大水平位移的增幅仅为29.7%,表明基坑开挖宽度对高铁站房的影响相对较小。

By conducting field tests and three-dimensional numerical simulations, the influence of basement excavation of the Hai’an High-speed Railway Station on the adjacent buildings was explored.The maximum pile displacement due to adjacent pile construction using MJS technique was less than 0.25 mm.Basement excavation-induced maximum lateral deformation in the retaining walls is controlled within in(0.045%~0.11%) H(H is excavation depth).Since the piles of high-speed railway station are embedded in silt sand stratum, basement excavation-induced lateral movement in the piles are much larger than the upper building settlement.When the clear distance between the pile foundation and basement reaches 1.5H, the horizontal movement of pile foundation is close to zero.It is indicated that the influence zone of basement excavation on adjacent building is 1.5H(His final excavation depth).By increasing the thickness of the retaining wall from 0.3 m to 0.63 m, the maximum horizontal displacement of the pile foundation is reduced by 68.7%. By further increasing the wall thickness, the decrease in the horizontal displacement of the pile foundation is not obvious.By increasing the excavation width from 0.83Hto 2.0H, the maximum horizontal displacement of the pile foundation tends to be stable, and the increase in the maximum horizontal displacement of the pile foundation is 29.7%.It is indicated that the excavation width has relatively small influence on the pile supported station building.