基于预应力锚和自应力注的深部裂隙岩体锚注加固机制研究

Research on mechanism of bolt-grouting reinforcement for deep fractured rock mass based on prestressed anchor and self-stress grouting

针对深部裂隙岩体水泥基注浆加固后由于材料自收缩造成浆岩界面松弛及充填空隙的问题,提出了基于预应力锚和自应力注的裂隙岩体锚注加固方法。建立了单裂隙岩体的自应力浆液加固模型和新型预应力锚注加固模型,通过物理试验研究普通锚注和新型预应力锚注加固裂隙砂岩试样的力学特征,通过工程应用验证了新型预应力锚注加固的有效性。结果表明:在一定范围内浆液膨胀约束应力越大,对裂隙岩体的加固作用越强,浆液膨胀约束应力和锚杆轴向应力对裂隙岩体最大主应力的提高呈叠加关系;新型预应力锚注加固砂岩的峰值强度比普通锚注加固砂岩提高了10%以上,其峰值应变略低于普通锚注加固砂岩,新型预应力锚注砂岩的弹性变形阶段缩短,加固效果增强;锚网索支护、U36型钢支架支护、普通锚注支护均未能有效控制的变电所巷道围岩采用新型预应力锚注加固后,巷道表面围岩最大位移为83 mm,控制效果较好。

To solve the problem of grout-rock interface relaxation due to self-shrinkage of cement-based material grouting in deep fractured rock masses,a bolt-grouting reinforcement method for deep fractured rock masses based on prestressed anchor and self-stress grouting was proposed.A self-stressed grouting reinforcement model and a new prestressed bolt-grouting reinforcement model for a single fractured rock mass were established.The mechanical characteristics of fractured sandstone specimens with ordinary and new bolt-grouting reinforcement were studied in physical experiments.The effectiveness of the new prestressed bolt-grouting reinforced rock mass was verified in engineering applications.Results showed that within a certain range,the greater the expansion restraint stress of the slurry stone is,the stronger the reinforcement effect on the fractured rock mass is.The expansion restraint stress of the slurry stone and the axial stress of bolt both contributed to the increase of the maximum principal stress of the fractured rock mass.The peak strength of the new prestressed bolt-grouting reinforced sandstone was 10%higher than that of the ordinary bolt-grouting reinforced sandstone.Its peak strain was slightly lower than that of the ordinary bolt-grouting reinforced sandstone.Moreover,the elastic deformation stage of the new prestressed anchor-grouting reinforced sandstone was shortened,and its reinforcement effect was enhanced.The surrounding rock of the substation roadway,which could not be well controlled by anchor-net support,U36 steel support or ordinary bolt-grouting reinforcement,was effectively controlled by new prestressed bolt-grouting reinforcement,and the maximum displacement of the surrounding rock on the roadway surface was 83 mm.