基于三轴压缩试验的软岩遇水强度软化规律研究
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摘要
针对软岩遇水软化导致强度降低的现象,对云南省富源县的典型软岩试样进行了三轴压缩试验,讨论了软岩遇水软化的强度变化规律。试验首先获取了该软岩的矿物成分、扫描电镜图片和浸水前后的结构状态变化;然后分别对天然状态和饱水状态的两种试样开展了常规三轴压缩试验,测定不同围压(1、3、5 MPa)下的应力-应变关系曲线。试验结果表明:软岩在浸水12h后,其岩体结构出现明显的崩解现象,表明软岩的水敏性较强;分析软岩的三轴应力-应变曲线可以看出该试样主要经历初始压密、线弹性变形、塑性变形和破坏后软化4个阶段;通过对比两种状态试样的峰值强度发现该软岩试样的软化程度随围压的增加有一定程度的减弱。研究结果对于围岩支护工程中软岩的长期稳定性分析具有一定的参考价值。
In view of the phenomenon that soft rock softness in water leads to the decrease of strength,the triaxial compression test was carried out on typical soft rock samples in Fuyuan,Yunnan to discuss the strength change rule of soft rock softness in water.Firstly,the mineral composition,scanning electron microscope(sem)images and pre-post immersion structural state changes of the soft rock were obtained in the tests.Then,conventional triaxial compression tests were carried out on two samples in natural state and saturated state respectively to measure the stress-strain relationship curves under different confining pressures(1,3 and 5 MPa).The experimental results show that after the soft rock is immersed in water for 12 hours,its rock mass structure appears obvious disintegration phenomenon,indicating that the soft rock has strong water sensitivity.By analyzing the triaxial stress-strain curve of soft rock,it can be seen that the sample mainly goes through four stages:initial compaction,linear elastic deformation,plastic deformation and softening after failure.By comparing the peak strength of the two samples,it is found that the softening degree of the soft rock samples decreases with the increase of confining pressure.The research results have certain reference value for the long-term stability analysis of soft rock in surrounding rock support engineering.
In view of the phenomenon that soft rock softness in water leads to the decrease of strength,the triaxial compression test was carried out on typical soft rock samples in Fuyuan,Yunnan to discuss the strength change rule of soft rock softness in water.Firstly,the mineral composition,scanning electron microscope(sem)images and pre-post immersion structural state changes of the soft rock were obtained in the tests.Then,conventional triaxial compression tests were carried out on two samples in natural state and saturated state respectively to measure the stress-strain relationship curves under different confining pressures(1,3 and 5 MPa).The experimental results show that after the soft rock is immersed in water for 12 hours,its rock mass structure appears obvious disintegration phenomenon,indicating that the soft rock has strong water sensitivity.By analyzing the triaxial stress-strain curve of soft rock,it can be seen that the sample mainly goes through four stages:initial compaction,linear elastic deformation,plastic deformation and softening after failure.By comparing the peak strength of the two samples,it is found that the softening degree of the soft rock samples decreases with the increase of confining pressure.The research results have certain reference value for the long-term stability analysis of soft rock in surrounding rock support engineering.
引文
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