考虑黏度时变性的水泥浆液盾构壁后注浆扩散规律及管片压力模型的试验研究

对水泥浆液黏度时变性进行了试验研究,证实了工程常用水灰比范围内水泥浆液服从宾汉姆流体特性;不同水灰比浆液黏度均随注浆时间增大而大幅度增加。根据试验结果,考虑注浆过程中水泥浆液黏度随时间的变化,对盾构壁后注浆水泥浆液的扩散规律及因注浆而造成的管片压力进行了推导及分析。计算表明:相同注浆时间条件下,水泥浆液扩散半径及注浆对管片产生的压力值均随注浆压力的增大而增大。考虑浆液黏度时变性后,扩散半径、注浆对管片压力值等均较不考虑浆液时变性时减小,且随注浆压力的增大,浆液黏度变化对管片压力值的影响更加明显。相同注浆压力条件下,浆液扩散半径及对管片产生的压力值均随注浆时间的增长而增加,但注浆前期增长速度较快,而后逐渐减缓。研究成果对于盾构壁后注浆工艺选择及参数设计具有较大的指导意义。

Backfilled grouting diffusion law and model of pressure on segments of shield tunnel considering viscosity variation of cement grout

Tests for time-dependent characteristics of cement grout are carried out, which find that cement grout of commonly used water-cement ratio conforms to Bingham fluid. Viscosities of grouts with different water-cement ratios increase greatly as grouting time increasing. According to the experimental results, considering the time-dependent characteristics of viscosity of cement grout, the diffusion law and model of pressure on segments of shield tunnel of backfilled cement grouting are found and derived respectively. A case is given. The results from theoretical calculation show that diffusion radius and pressure on the segments increase with the increase of grouting pressure when grouting time is constant on one hand. After considering viscosity variation of cement grout, diffusion radius and pressure on segment are smaller than the results obtained under fixed viscosity; and as the grouting pressure increases, the disturbance on pressure from viscosity of grout gets more obviously. On the other hand: when grouting pressure is constant, diffusion radius and pressure on the segments increase with the increase of grouting time. However, the values increase rapidly in the beginning and slow down later. The results can provide a guide to selecting appropriate techniques and parameters of cement grouting.