顶管管节壁后触变泥浆探地雷达探测研究

采用探地雷达对顶管顶进中管节壁后触变泥浆进行探测,通过对雷达探测图像的数据处理及解译测得触变泥浆的相对介电常数,获得管节壁后触变泥浆套的分布状况。结果表明:管节壁后泥浆套厚度并非均匀一致,但沿顶进方向能够形成致密的泥浆套且其厚度为理论建筑空隙厚度的8~17倍,而实际施工中泥浆套厚度为建筑空隙的6~7倍时即能达到同样的减摩效果,本次雷达探测能够优化顶管施工质量;此外,通过与盾构隧道管片壁后注浆进行对比发现:电磁波在顶管触变泥浆中的传播速度明显小于其在盾构隧道浆液的传播速度,浆液的含水量及水化速度是影响电磁波在介质中传播速度的关键。

Application of GPR to Detect Thixotropic Clay Slurry outside the Tube of Pipe Jacking

The thixotropic clay slurry outside the tube of pipe jacking was detected by the Ground Penetrating Radar(GPR). The thickness distribution of thixotropic clay slurry was obtained by the collected radar detection image after data processing, interpretation and the propagation velocity of electromagnetic wave in clay slurry derived from dielectric property test for thixotropic clay slurry samples. The results show that although the thickness of clay slurry was inconsistent in different sections, clay slurry could be formed along the longitudinal tube, and the thickness of the slurry detected was 8 to17 times of the thickness of the building gap, however, the anti-friction effect could be achieved when the ratio was 6 to 7, this radar detection realized the function to optimize the pipe jacking construction. In addition, the velocity of electromagnetic wave in clay slurry of pipe jacking is significantly slower when compared with the grouting behind the segment of shield tunnel, meanwhile the water content and hydration speed of slurry are the key factors which influence the velocity of electromagnetic wave.