矩形顶管管土接触状态及顶进力研究

Study on Pipe-Soil Contact State and Jacking Force of Rectangular Jacking

为了合理预测矩形顶管管周摩阻力,进而更加精确地确定顶进力,对矩形顶管的管土接触状态进行分析发现:注浆效果良好时,矩形管节在泥浆中处于上浮状态;注浆效果一般或土体稳定性较差时,管土接触状态倾向于全接触。在此基础上提出管土全接触、管顶及两侧与土体接触、管顶及一侧与土体接触和管顶与土体接触为4种最有可能的接触状态。分别进行管土和管浆摩阻力理论计算公式的推导,结果表明:管浆摩阻力可以忽略,采取太沙基竖向土压力理论可以较好地预测矩形顶管管顶竖向压力大小,据此建立了不同管土接触状态下的管周摩阻力计算模型。考虑不同管土接触状态,开展矩形顶管顶进数值模拟,通过与工程实测顶进力进行对比,结果表明:在管顶及一侧与土体接触的假设下,数值模拟和理论计算得到的顶进力与实测值误差分别为13.2%和8.5%。

In order to reasonably predict the pipe friction resistance of rectangular pipe jacking and determine the jacking force more accurately,the pipe-soil contact state of rectangular pipe jacking is analyzed.When the grouting effect was good,the rectangular pipe section was floating in the mud;when the grouting effect was poor or the soil stability was poor,the contact state of pipe soil tended to be full contact.On this basis the four most likely contact states were full contact,contact on pipe roof together with both sides,contact on pipe roof together with one side,and contact on pipe roof.The theoretical calculation formulas of friction resistance between pipe and soil or slurry were derived respectively,the calculation results showed that the friction resistance could be ignored,the vertical pressure of rectangular jacking pipe could be well predicted by using the Terzaghi vertical earth pressure theory,and then the calculation models of friction resistance around pipe under different contact states were established.The numerical simulation of rectangular pipe jacking was carried out considering different pipesoil contact states.Compared with the actual jacking force,the results showed that the errors between the numerical simulation and theoretical calculation and the measured value were only 13.2%and 8.5%respectively under the assumption that the pipe roof together with one side contacted with the soil.