无水砂层地区顶管施工注浆减阻关键技术及作用机理分析

Key Technology and Mechanism Analysis of Grouting Drag Reduction in Pipe Jacking Construction in Anhydrous Sand Layer

本文基于乌兰布和沙漠引水工程,针对无水砂层顶管注浆减阻施工中顶力及注浆量异常波动且不可控的问题,采用室内试验结合工程现场施工要求的方法,配制出适用于无水砂层地区顶管施工性能要求的泥浆。通过改良泥浆配方后的顶力监测数据与试验段监测数据对比,验证了泥浆配比改良后的护壁效果,并得出如下结论:(1)由于泥浆性能不足,泥浆渗透进入土层后会进一步降低本就自稳能力极差的受扰动的干砂围岩强度,从而导致隧道孔壁坍塌,这是无水砂层地区顶管施工泥浆减阻效果不佳的主要原因;(2)在工程施工允许范围内,通过提升泥浆的黏度等流变性能参数,能够有效提升无水砂层地区顶管施工泥浆的护壁减阻效果;(3)泥浆的减阻能力首先应保证隧道孔壁不发生坍塌,这样才能更好地体现其润滑效果。

Based on the Ulan Bu and Desert Water Diversion Project,this paper aims at the problem of abnormal fluctuations and uncontrollable jacking force and grouting amount in the construction of pipe jacking and drag reduction in anhydrous sand layer,and uses indoor experiments combined with the construction requirements of the project site to prepare a mud suitable for the construction performance requirements of pipe jacking in anhydrous sand layer areas,and verifies the effect of the improved mud ratio and the retaining wall effect of the improved mud ratio by comparing the top force monitoring data after the improved mud formula with the monitoring data of the test section.And the following conclusions are drawn:1.Due to the insufficient performance of the mud,the strength of the disturbed dry sand surrounding rock that is already very poor in self-stabilizing ability is further reduced after the mud penetrates into the soil layer,resulting in the collapse of the tunnel hole wall,which is the main reason for the poor drag reduction effect of the pipe jacking construction in the anhydrous sand layer area;2.By improving the rheological performance parameters such as the viscosity of the mud within the allowable range of engineering construction,the drag reduction effect of the pipe jacking construction mud in the anhydrous sand layer area can be effectively improved;3.The drag reduction ability of mud should first ensure that the tunnel wall does not collapse,in order to better reflect its lubrication effect.