长期浸泡作用下灌浆加固裂隙岩体劣化效应

The deterioration effect of fractured rock mass strengthened by grouting method under long-term immersion

为分析灌浆加固裂隙岩体在压力水长期浸泡作用下力学性能的劣化效应,在前期碳纤维水泥基复合灌浆材料加固裂隙岩体研究基础上开展了考虑水压力影响的灌浆加固裂隙岩体长期浸泡试验和在不同浸泡周进行直剪试验。研究结果表明,(1)压力水长期浸泡作用下灌浆加固裂隙岩样的剪应力-剪切位移曲线形态变化趋势明显,剪切刚度逐渐减小,达到峰值抗剪强度时的剪切位移逐渐增大;(2)随着浸泡周期增加,灌浆加固裂隙岩体的抗剪强度呈先陡后缓的劣化趋势,6个浸泡周期(150 d)后不同法向应力下峰值抗剪强度的劣化幅度为32.6%~39.9%,对应内摩擦角和黏聚力分别降低了19.3%、39.4%,其中前4个浸泡周期(0~90 d)抗剪强度参数劣化幅度占总劣化幅度的90%左右;(3)水压力作用下裂隙岩样发生溶解、溶蚀、润滑、软化等物理化学作用,浆体中的凝胶体被进入浆体内部的水分子软化,导致裂隙岩体和灌浆体本身的力学性质逐渐劣化,浆体与裂隙面之间的胶结作用、浆体与碳纤维之间粘结性能逐渐减弱,使得灌浆加固裂隙岩体抗剪性能逐渐劣化,剪切破坏面逐渐发展到浆体与裂隙面之间的胶结面。相关研究成果可为灌浆加固裂隙岩体的长期稳定性分析评价提供参考。

In order to analyze the deterioration effect of mechanical properties of the fractured rocks strengthened by grouting in a long-term immersion in pressurized water,the long-term immersion tests of reinforced fractured rock samples considering the influence of water pressure.These tests are based on the earlier research of strengthening the fractured rock mass using carbon fiber reinforced cement-based composites mixed with grouting materials.Besides,the shear tests were also carried out in different immersion periods.The results show that:(1)a significant change trend of the shear stress-shear displacement occurs for the fractured rock samples reinforced by grouting and immersed in the pressure water in the long-term,with the shear stiffness gradually decreases,and the shear displacement gradually increases when the shear strength reaches to its peak.(2)With the longer immersion period,shear strength of reinforced fractured rock mass shows a sharp degradation trend at first,and then a gentle degradation.After 6 cycles of soak periods(i.e.150 days),the degradation rate of the maximum shear strength under different normal stresses is in the range of32.6%-39.9%.It means that the internal friction angle and cohesion is reduced by 19.3%and 39.4%,respectively.The shear strength parameters in the first four soaking periods(0-90 d)account for about 90%of the total deterioration range.(3)Dissolution,corrosion,lubrication,softening of the fractured rocks occurs in the pressurized water.Besides,the gel in the slurry is softened by the water molecules entering into the interior of the slurry,which result in a gradually deterioration in mechanical properties of fractured rocks and grouting.Meanwhile,cementation between the slurry and fracture surface,and bond performance between the slurry and carbon fiber are gradually weakened.As a result,shear performance of grouting reinforced fractured rocks gradually deteriorates,and shear failure surface gradually developed to cementation surface between the slurry and fracture surface.The experimental results in this paper can provide reference for the long-term evaluation on stability analysis of fractured rock mass reinforced by grouting method.