砂层劈裂–压密注浆模拟试验系统研发及试验

Simulation tests on fracture-compaction grouting process in sand layer

劈裂–压密模式是砂层注浆扩散过程的主要模式之一。为研究砂层劈裂–压密注浆扩散过程,研发了一套可视化注浆模拟试验系统,该系统由模拟试验架、地应力加载模块、动态监测模块以及注浆控制模块4部分构成,可实现劈裂–压密注浆扩散过程的可视化模拟。以青岛地区含黏性土砂层为典型被注介质,开展了砂层劈裂–压密注浆模拟试验,揭示了注浆扩散过程中劈裂通道形态、注浆压力、应力场以及位移场随时间变化规律,获得了试验条件下的砂层劈裂–压密注浆影响范围。研究结果表明:砂层注浆起裂方向与劈裂通道扩展方向均与大主应力方向一致,浆脉厚度在浆脉扩展方向上存在明显衰减;注浆会引起与劈裂通道垂直方向的应力增加,且该应力沿劈裂通道扩展方向衰减,但注浆对平行劈裂通道扩展方向的应力没有显著影响;劈裂–压密注浆对劈裂通道两侧砂层的影响范围非常有限(20～40cm)。最后从单孔注浆量、钻孔布置方面对砂层劈裂–压密注浆设计方法提出了改进建议。

The fracture-compaction mode is the main diffusion mode of grouting process in sand layer.In order to study the diffusion process of fracture-compaction grouting mode in sand layer,a visible grouting simulation test system composed of test frame,stress loading module,dynamic monitoring module and grouting module is designed and developed.As the typical grouted medium,the clayey sand in Qingdao is used in the fracture-compaction grouting simulation tests.The characteristics of the dynamic evolution of the stress and displacement fields of sand layer and the propagation of fracture channel are derived.The influence scope of fracture-compaction grouting in sand layer is obtained.The results show that the initiation and propagation of fracture channel direction are consistent with those of the major principal stress in sand layer.The width of grouting vein decreases remarkably along the propagation direction.Under the influences of grouting,the vertical stress increases from the minor principal stress and decays spatially along the propagation direction.However,the horizontal stress has no obvious changes in the grouting process.The influence scope of fracture-compaction grouting in sand layer is very limited(20~40 cm).Finally,improvement suggestions for fracture-compaction grouting in sand layer are put forward from two aspects(grouting amount of single hole and arrangement of injection hole).