黄土劈裂注浆过程数值模拟研究

Numerical Simulation of Fracture Grouting in Loess

劈裂注浆广泛应用于岩土工程用来改善土体的力学性能和降低土体的渗透性,然而,劈裂注浆过程中浆液扩散的全过程难以得到。为此,采用PFC2D离散元软件,研究得到了黄土劈裂注浆中劈裂缝的产生与扩展的全过程,以及注浆压力对浆脉扩展形态的影响规律。结果表明,整个劈裂注浆的过程中,土体孔隙率在土体二次劈裂之后增加明显。劈裂缝尖端形成拉应力集中,而劈裂缝的扩展主要是由劈裂缝尖端的拉应力引起。注浆压力对浆脉的扩展影响明显,随注浆压力的增大,浆脉分支的数量增多,注浆孔周边土体孔隙率增大。研究结果可为实际注浆工程中注浆参数的优化提供技术支撑。

Fracture grouting is widely used in tunnel engineering to improve the mechanical properties and reduce the permeability of soils.However,the processes of slurry diffusion in soil are difficult to directly observe.Therefore,by using the PFC2D discrete element software,the process of the generation and expansion of split cracks during fracture grouting in loess area,as well as the influence of grouting pressure and confining pressure on the propagation pattern of grout veins are studied.The results reveal the following,during the whole process of splitting and grouting,the porosity of soil increases significantly after the secondary splitting.The tensile stress is concentrated at the tip of the split crack,which is the main cause of the expansion of split cracks.The grouting pressure has a significant influence on the expansion of grout veins.With the increase of the grouting pressure,more grout vein branches appear,and the porosity of the soil around the grouting hole increases.The results obtained in this paper can provide technical support for optimization of the grouting parameter.