基于浆液稠度时空变化的盾构隧道壁后注浆扩散机制

Grouting diffusion mechanism after shield wall based on spatial and temporal variation of slurry consistency

研究考虑幂律水泥浆液稠度时空变化对盾构隧道壁后注浆扩散半径及力学性质影响。首先,针对不同水灰比水泥浆液进行稠度时变性试验,简要分析浆液稠度时变规律,并获取各水灰比水泥浆液稠度时变系数;其次,分析盾构隧道壁后注浆扩散机理,重点研究浆液扩散稠度时空分布不均匀性;再次,建立恒定注浆速率条件下,考虑浆液稠度时空变化不均匀隧道壁后注浆的扩散模型,并推导浆液压力及管片承压时间与空间的分布方程,确定浆液注浆压力的时变规律;最后,以实际工程为例,分析注浆终压与管片承受压力、浆液扩散半径及注浆浆液压强时空分布的关系,并对比分析考虑与不考虑浆液稠度空间分布不均匀性的扩散半径及管片受力结果。研究结果表明:浆液质点的压强随距离注浆孔位置增加而减小;当注浆终压较低时,注浆浆液扩散半径随注浆终压增大而迅速提高;盾构隧道管片注浆终压增大,管片所承受的注浆总压力迅速增大;不考虑浆液空间分布不均匀性所得注浆压力为正常值的60倍以上,所得浆液扩散半径约为正常值的1/3,管片承受总压力相差20倍以上。

The effect of considering the power-law cement slurry consistency time-variation on the diffusion radius and mechanical properties of the slurry injected behind the shield tunnel wall was studied.Firstly,a timevarying consistency test was conducted for cement slurries with different water-cement ratios,brief analysis of the time-varying slurry consistency law was carried out,and the time-varying coefficients of cement slurry consistency for each water-cement ratio were obtained.Secondly,the mechanism of slurry diffusion in the shield tunnel wall post-injection grouting was analyzed,focusing on the inhomogeneity of the spatial and temporal distribution of the slurry diffusion consistency.Further,the diffusion model of post-wall slurry injection under constant grouting rate conditions,considering the spatial and temporal variation of slurry consistency,was established.The distribution equations of slurry pressure and tube sheet pressure-bearing time and space were derived to determine the time-varying law of slurry injection pressure.Finally,the relationship between final pressure of slurry injection and pressure on the tube sheet,spatial and temporal distribution of slurry diffusion radius and pressure of the slurry injection was analyzed by taking the actual project as an example.The results of the diffusion radius and the tube sheet force with and without considering the inhomogeneity of the spatial distribution of the slurry consistency were compared and analyzed.The results show that the pressure of slurry mass decreases with the increase of distance from the grouting hole position.When the final pressure of grouting is low,the diffusion radius of grouting slurry rapidly increases with the increase of final pressure of grouting.When the final pressure of shield tunnel tube piece grouting increases,the total pressure of grouting borne by the tube piece increases rapidly.The grouting pressure obtained without considering the unevenness of slurry spatial distribution is more than 60 times of the normal value,the resulting slurry diffusion radius is about 1/3 of the normal value,and the total pressure borne by the tube piece differs by more than 20 times.