溶蚀岩体各向异性力学性质的试验研究

Experimental Study on Anisotropy Mechanical Properties of Corroded Rock Mass

溶蚀岩体通常对岩体工程稳定性具有关键控制作用.为了揭示富含层理溶蚀岩体各向异性力学性质演化规律,分别针对不同溶蚀率(K=0%,5%,10%,15%,20%)的岩体进行室内单轴抗压试验,获取每种溶蚀率条件下不同夹角(α=0°,30°,45°,60°,90°)抗压强度和弹性模量,分析岩体破坏特征,依据试验结果建立含层理溶蚀岩体抗压强度和弹性模量的预测模型,并进行实验验证.结果表明:抗压强度在α=0°,90°时最大,α=45°时最小,整体呈现对称U形;弹性模量在α=60°最小,α=90°最大,整体呈现不对称U形;完整岩体抗压强度以及弹性模量的各向异性指数最大,分别为1.98、3.05,随着溶蚀率增大其值逐渐减小,K=20%时,分别为1.10、1.36;溶蚀率较小岩体变形破坏受岩体基质和层理控制,以劈裂、错动剪切和滑动剪切为主;随着溶蚀率增大,变形破坏受溶蚀孔隙和骨架控制明显,以骨架鼓胀剪切错动、压碎破坏为主.

Corroded rock mass usually plays a key role in controlling the stability of rock mass engineering.In order to reveal the evolution law of anisotropic mechanical properties and failure characteristics of the bedded rock mass suffering corrosions,indoor uniaxial compression tests were carried out on rock masses with different corrosion rates(K=0%,5%,10%,15%,20%)to obtain their compressive strength and elastic modulus at different included angles(α=0°,30°,45°,60°,90°).Based on the test results,mathematic models for predicting the compressive strength and elastic modulus of the corroded rock mass with beddings were established and then validated by experiment.The results show that the compressive strength achieves its maximum value at the included angleα=0°,90°,and achieves its minimum value atα=45°,presenting a symmetrical U shape as a whole;while the elastic modulus is the smallest atα=60°and the largest atα=90°,showing an asymmetric U shape as a whole.The anisotropy indexes of compressive strength and elastic modulus(i.e.,RP and RE)of the intact rock mass are the largest,which are 1.98 and 3.05 respectively,and their values gradually decrease with the corrosion rate increasing.When K=20%,RP and RE are 1.10 and 1.36,respectively.The deformation and failure of rock mass with small corrosion rates are controlled by rock matrix and beddings,mainly by splitting,staggered shear and sliding shear.As the corrosion rate increases,the deformation and failure are obviously controlled by dissolution pores and skeleton,and the skeleton swelling,shear dislocation and crushing failure are the main types.