矩形顶管管周差异摩阻力对地层纵向水平位移的影响

矩形顶管施工过程中管周摩阻力是引起周围土体扰动的重要影响因素。为了更加准确地预测矩形顶管施工对地层位移的影响，结合管节受力分析和泥浆运动规律，假定“U”字形泥浆套状态，基于弹性力学Mindlin解建立土体水平位移计算公式，对正面附加应力、管周摩阻力等因素引起的地层纵向水平位移进行计算，最后与苏州某矩形顶管工程实测值进行对比分析。结果表明:在顶管机头顶进穿过某一断面前，正面附加应力对周围土体的影响大于管周差异摩阻力，而在穿过该断面后，由于管节数量的增多以及已穿过部分的管节管周摩阻力产生的“拉力”作用，后者的累计影响占比逐渐大于前者；管周差异摩阻力情况下比管周均一摩阻力情况下的计算值更贴近实测值，预测效果更好。 

Influence of differential frictional resistance around rectangular pipe jacking on longitudinal horizontal displacement of strata

In the process of rectangular box jacking, the friction resistance around the pipe is an important factor that causes the disturbance of the surrounding soil. To predict the influence of rectangular pipe jacking construction on stratum displacement more accurately, the calculation formula of horizontal displacement of soil is established based on the Mindlin solution of elastic mechanics, assuming the state of 'U' shaped mud sleeve combined with the stress analysis of pipe joint and the law of mud movement, and the vertical-horizontal displacement of stratum caused by additional stress on the front and friction resistance around the pipe is calculated. Finally, it is compared with the measured values of a rectangular box jacking project in Suzhou. The results show that before the pipe jacking head passes through a certain fracture, the effect of the additional stress on the surrounding soil is greater than the differential friction resistance around the pipe.However, after crossing the section, the cumulative effect of the latter is gradually greater than the former due to the increase inthe number of pipe segments and the "pull" effect of the friction resistance around the pipe jacking that haspassed through. The calculated value in the case of differential friction resistance is closer to the measured value than that in the case of uniform friction resistance, and the prediction effect is better.