考虑水泥浆液析水作用的水平裂隙注浆扩散机制研究

Study on grouting mechanism of horizontal fractures considering the bleeding of cement slurry

水泥浆液是一种悬浊液且具有明显析水特性,浆液发生析水后,其自身黏度、密度明显变化,由此导致浆液在扩散区内黏度、密度等参数时空分布不均。为准确描述浆液发生析水后的裂隙注浆过程。简化浆液发生析水后在裂隙内的扩散运移形态,建立恒定注浆速率条件下,考虑浆液析水作用的裂隙注浆扩散理论模型,推导浆液扩散半径表达式与浆液微元体压力梯度方程。提出考虑析水作用的裂隙注浆计算方法,基于Matlab编程实现了浆液析水率与浆液压力的时空分布计算。利用自主研发的裂隙注浆模拟试验平台,对理论模型的合理性进行验证。研究结果表明,浆液析水率随浆液扩散距离的增加呈非线性变化;随着水灰比的增加,浆液析水率在空间上的分布差距明显增大;考虑浆液析水作用计算得到的注浆压力明显大于不考虑时的计算结果,并且随着浆液水灰比的增加,考虑析水与不考虑析水作用相比,二者计算得到的注浆压力差距越大;通过对比试验测试结果与理论计算值,理论计算得到的注浆压力是试验测试值的1.2～1.5倍,所建立的理论模型能够描述考虑析水作用下水泥浆液在裂隙中的扩散过程。

As a kind of suspension liquid,cement slurry has obvious characteristics of the bleeding.Once the bleeding occurs,the viscosity and the density of the slurry change obviously,which leads to the viscosity and the density of the slurry in time and space are not uniform at the penetration zone.In order to accurately describe the grouting process of the fracture under the function of the bleeding,a theoretical model of fracture grouting,considering the characteristic of cement bleeding,was established under the constant grouting rate,the expressions of the diffusion radius and the pressure gradient of slurry were derived,and a calculation method of fracture grouting considering the cement bleeding was put forward.Based on MATLAB programming,the distribution calculation of the bleeding rate and the grouting pressure in time and space was realized.The rationality of the theoretical model was verified by using the self-developed fracture grouting model test platform.The results show that the bleeding rate of the slurry shows a nonlinear change with the increase of the penetration length of the slurry.With increasing the water-cement ratio,the spatial distribution gap of the bleeding rate increases obviously.The grouting pressure calculated by considering cement bleeding is obviously higher than that of the unconsidered.With increasing the water-cement ratio of the slurry,the difference of the grouting pressure between two cases of considering and without considering cement bleeding rises.Comparison between the test results with the theoretical calculated values indicates that the grouting pressure obtained from the theoretical calculation is 1.2–1.5 times of the model test value.The established theoretical model can better describe the diffusion process of cement slurry in fracture grouting considering the effect of bleeding.