Diffusion radius is an important construction parameter, because it can significantly influence the grouting effectiveness. Theoretical models in predicting diffusion radius have been practiced, but there are still significant discrepancies between theoretical calculations and realistic results in the practical construction. One of the critical reasons for the misprediction is the time-dependent behavior of the cement grout, which is significantly affected by the water-cement ratio (W/C). Therefore, this paper experimentally and numerically studies the influence of W/C on the viscosity variation of the grout and grouting process. Firstly, the apparent viscosity of the cement grout under different W/C is tested by a rotational viscometer in a laboratory experiment. Subsequently, based on the laboratory tests, numerical models are established to investigate the influence of W/C on the diffusion process of cement grout in sand layers. According to the laboratory results, the apparent viscosity of cement grouts decreases with the increase of W/C. Besides, the apparent viscosity increases with time, while the increasing range of apparent viscosity firstly increases and then decreases as W/C increases. Based on the simulated results, when W/C changes from 0.8 to 1.1, the diffusion radius at 60 min experiences a less and less obvious increase under the given grouting pressure for permeation grouting in the sand layer. When W/C is 0.9, the relative error reaches to 37.65% at 60 min, which is slightly lower than that of 0.8. However, when W/C changes from 0.9 to 1.0, the relative error becomes very narrow (21.36%), and this figure is much lower than that of 0.8 or 0.9. The simulation results are verified by field test, and the relative error is 6%, which proves the effectiveness of the analysis. Therefore, the cement permeation model considering viscosity variation of the grout is a reasonable alternative in the real project. At the same time, the time-dependent behavior of cement grouts should be considered, especially when using cement grouts with a low water-cement ratio in the practical engineering.

中文翻译：

---

水灰比对渗透灌浆水泥浆粘度变化的影响

扩散半径是一个重要的施工参数，因为它可以显着影响注浆效果。预测扩散半径的理论模型已经得到实践，但在实际建设中，理论计算与实际结果仍存在较大差异。错误预测的关键原因之一是水泥浆随时间变化的行为，它受到水灰比 (W/C) 的显着影响。因此，本文通过实验和数值研究W/C对灌浆和灌浆过程的粘度变化的影响。首先，在实验室实验中，通过旋转粘度计测试了不同水灰比下水泥浆的表观粘度。随后，根据实验室测试，建立数值模型研究W/C对水泥浆在砂层中扩散过程的影响。根据实验室结果，水泥浆的表观粘度随着水灰比的增加而降低。此外，表观粘度随时间增加而增加，而表观粘度的增加范围随着W/C的增加而先增加后减小。根据模拟结果，当水灰比从 0.8 变为 1.1 时，在砂层渗透注浆给定注浆压力下，60 min 时的扩散半径增加越来越不明显。当水灰比为 0.9 时，60 min 时的相对误差达到 37.65%，略低于 0.8。但是，当W/C从0.9变为1.0时，相对误差变得很窄（21.36%），这个数字远低于0。8 或 0.9。仿真结果经现场试验验证，相对误差为6%，证明了分析的有效性。因此，考虑水泥浆粘度变化的水泥渗透模型在实际工程中是一个合理的替代方案。同时，应考虑水泥浆随时间变化的特性，尤其是在实际工程中使用低水灰比水泥浆时。