类砂质泥岩常规三轴浆压致裂起裂压力试验研究

为深入探究两淮矿区典型砂质泥岩劈裂注浆起裂机制，研制了常规三轴劈裂注浆试验装置，开展了类砂质泥岩浆压致裂起裂压力模型试验，基于试验结果分析了岩石强度与应力状态对注浆起裂压力、裂缝扩展形态影响规律，揭示了砂质泥岩劈裂注浆起裂机制。研究表明：起裂压力与岩石抗压强度呈正相关，且岩石抗压强度越高，劈裂路径越复杂；起裂压力对围压的敏感程度远高于轴压，且应力差 Δσ =σ_V ?σ_H越大，裂缝形态越规整；孔压三轴条件下，封闭裸孔段浆压致裂法确定的岩石抗拉强度值约为单轴抗拉强度的 2.5倍。该研究结果可为今后类似岩层劈裂注浆参数设计与施工提供参考。

Experimental research on fracture initiation pressure of conventional triaxial slurry fracturing in similar material of sandy mudstone

To further explore the fracture initiation mechanism of fracture grouting in typical sandy mudstone from Huainan and Huaibei mining areas in China, a conventional triaxial fracture grouting test device was developed, and the model test of fracture initiation pressure of slurry fracturing in similar material of sandy mudstone was carried out. Based on the test results, the influences of rock strength and stress state on grouting fracture initiation pressure and fracture propagation pattern were analyzed, and the fracture initiation mechanism of fracture grouting in sandy mudstone was revealed. The results show that there is a positive correlation between the initiation pressure and the compressive strength of rock; the larger the compressive strength of the rock is, the more complex the fracturing path is. The sensitivity of fracture initiation pressure to confining pressure is much greater than that of axial pressure; the larger the stress difference Δσ =σ_V ?σ_H is, the more regular the fracture shape is. Under the triaxial condition of pore pressure, the rock tensile strength determined by slurry fracturing method in sealed open hole section is approximately 2.5 times the uniaxial tensile strength. The research results can provide a reference for the design and construction of fracture grouting in similar rock strata in the future.