静压桩对邻近埋地管道性能影响的数值分析
Numerical Analysis of Effect of Jacked Pile on Performance of Buried Pipes

为了分析静压沉桩过程对邻近埋地管道性能的影响，基于位移贯入法模拟静压沉桩的二维有限元数值方法，建立了桩-土、管-土接触面并在桩顶施加位移荷载实现动态压桩过程，并综合分析了压桩过程中沉桩深度、桩径大小、管道中心与桩体中心的水平距离以及管道的埋深等因素对管道变形与力学性能的影响.研究结果表明：同等条件下，增加管-桩水平距离，管道水平位移、径向变形和管周应力相应减小，近桩侧管周土体的最大水平应力约为不设置管道时的1.5倍；随着沉桩深度增大，初始使管道产生明显水平位移的临界沉桩深度约为管道上方1 m处，随后管道水平位移呈现先增大后略微减小，并最终趋于稳定的趋势，且当沉桩深度为2倍埋深时管道水平位移最大；管道埋深越大，管道受沉桩挤土效应的影响越明显；当埋深为5倍管径时，沉桩桩径减少25%时管道最大水平位移减少27.8%，表明减小桩径可显著降低沉桩对周边管道性能的影响.
：To analyse the influence of the driving process of jacked piles on the performance of adjacent buried pipes via the planar finite element method numerical simulation based on the displacement penetration method and achieve the dynamic pile driving process by establishing the pile-soil and pipe-soil contact surfaces and applying the displacement load at the top of the pile, comprehensive analysis was carried out to investigate the effect of the pile penetration depth, pile diameter, horizontal centre distance between the pile and buried pipe, and buried depth, on the performance of buried pipes during pile driving. The calculation results showed that when keeping other parameters identical and first increasing the horizontal distance, caused a decrease in the horizontal displacement, radial deformation, and stresses of pipes. The maximum horizontal stress of the soil surrounding the pipes is 1.5 times that of the soil without pipes. Secondly, with the increase in the pile penetration depth, there exists a critical penetration depth, after reaching it, the horizontal displacement of pipes increases significantly, then somewhat decreases, and finally becomes steady. Moreover, the maximum horizontal displacement of pipes can be reached when the penetration depth is equal to 2 times the buried depth of the pipe. Thirdly, increasing the buried depth of the pipe results in remarkable change in the deformation and mechanical performance of the pipes. For a buried depth of 5 times the diameter of pipe, the maximum horizontal displacement of the pipes reduced by 27.8% when the pile diameter decreased by 25%. This implied that reducing the diameter of jacked piles can considerably weaken its effect on buried pipes