Experimental and Simulation Study on the Influence of Slurry Thixotropy on Jacking Force of Pipe Jacking

Jacking force is the core basis for structural design and equipment selection in pipe jacking engineering. It is of great significance to optimize construction control by deeply exploring the influence mechanism of slurry thixotropy on jacking force. Aiming at the aging problem of thixotropic mud standing under the condition of soil-rock composite stratum, this paper takes Chongqing Hengda track age project as the engineering support, and studies the jacking force variation law of thixotropic mud after standing time of 24 h, 48 h and 72 h by carrying out model test with similarity ratio of 1:20 and ABAQUS numerical simulation. The test results show that the jacking force increases nonlinearly with the standing time. Under the working conditions of 24 h, 48 h and 72 h, the jacking force of the first pipe section replacement reaches 285.5 N, 299.1 N and 312.6 N, respectively, with an increase of 43.2%, 50.0% and 56.8%, respectively. The evolution of the friction ratio shows a three-stage characteristic of “sudden rise-attenuation-stability”, and the friction ratio is significantly positively correlated with the standing time. The numerical simulation shows that the increase of jacking force increases with time after standing, and the thixotropic activation efficiency decreases from 0.105 to 0.033, indicating that the reconstruction ability of slurry structure decreases significantly with the extension of standing time. The research results can provide theoretical support for the risk control of pipe jacking construction shutdown in soil-rock composite strata.