基于D-Rb-C耦合模型的破碎岩体注浆加固作用机制与规律

Mechanism of grouting diffusion and consolidation of rock mass based on D-Rb-C coupled model

注浆加固是工程岩体稳定性主动控制的有效方法,其作用机制主要是将浆液注入或渗入破碎岩体结构面中,形成注浆结实体,强化岩体稳定性和抵抗外力破坏的能力。为实现破碎围岩注浆扩散和固结全过程计算,提出了基于离散单元法的岩体注浆扩散-固结作用机制,考虑了注浆过程中离散单元体中的完整接触、水力破坏接触和力学破坏接触3种情况,建立了Bingham流体扩散-黏结-固结(D-Rb-C)耦合模型,给出了基于D-Rb-C耦合模型的解算原理,开展了模型校核和算例分析,实现了浆液扩散-黏结-固结全过程解算,结果表明:(1)单裂隙岩体全长注浆后,岩体剪切峰值强度较未注浆裂隙有一定提升,主要依赖于浆液凝固后所产生的剪切摩擦阻力;(2)在单裂隙岩体点注浆模拟实验中,随着注浆压力增加浆液不断扩散,岩体峰前剪切屈服阶段和峰后阶段不断强化。(3)对于工程尺度破碎岩体,随着注浆压力增加,扩散半径呈两阶段增大趋势;浆液向深处高应力区闭合裂隙扩展需克服更大压应力,才能继续流动;注浆压力升高以后,相邻钻孔扩散范围叠加,形成封闭巷道的注浆结石体;当浆液凝固黏结强度较低时,结构面仍是控制围岩破坏失稳的主控因素。

Grouting reinforcement is an effective method for controlling the stability of engineering rock mass.The mechanism is mainly to inject or infiltrate the grout into the fracture of rock mass to form a grouting entity,and strengthen the stability of rock mass and the ability to resist failures.In order to realize the calculation of the whole process of grouting diffusion and consolidation in broken surrounding rock,a diffusion-consolidation mechanism of grouting based on dis-crete element method was proposed.Also,the model checking and example analysis were carried out,and the results show that:①In the full-length grouting of single fracture scenario,the shear peak strength of the post-fractured rock mass is higher than that of the non-grouting fracture,which depends on the frictional resistance generated by the solidification and cohesion of the slurry.②In the point grouting simulation experiment,as the grouting pressure increases,the grout contin-ues to diffuse.Therefore,the pre-peak shear yielding and post-peak phases of the rock mass are strengthened.③For the engineering-scale simulation test,as the grouting pressure increases,the diffusion radius increases in two stages.When the grout expands to the high-stress area,it needs to overcome a greater compressive stress to achieve flow.After reaching a relative higher grouting pressure,the diffusion area of adjacent boreholes is superimposed to form a grouting whole body that surrounds the roadway.When the solidification bond strength of the grout is low,the failure of contact is still the main controlling factor to determine the failure and instability of the roadway.