水体浸润作用下含原生裂隙岩石剪切性能及破断规律研究

Study on shear performance and fracture law of rock with primary cracks under influence of water infiltration

原生裂隙和水体会改变岩石物理力学特性,易诱发地质灾害。因此,水—裂隙作用下岩体失稳破坏行为特征成为当前地下岩土工程领域重要研究内容之一。基于D-P准则提出了不同含水条件下裂隙岩石断裂破坏临界条件,分析了原生裂隙影响下岩石可能存在的新生裂隙发育扩展形态,并对含水红砂岩开展剪切试验。结果表明,在本次试验范围内,含水裂隙岩样与预制原生裂隙以20°角为界呈分段式演化,随裂隙倾角增大,演变趋势由正相关转为负相关,20°时含水裂隙岩样抗剪强度最大;随含水率增大,水体浸润对岩样抗剪性能损伤弱化程度的增量减小,在含水率1.213%之后,随含水率继续增大,对岩样抗剪性能损伤弱化程度由增转降,可知饱和含水对裂隙岩样损伤弱化程度小于非饱和含水。剪切破坏面破坏形态呈现出剪切破坏—剪切破坏主导的拉剪复合破坏—拉剪复合破坏—拉伸破坏主导的拉剪复合破坏的变化趋势。研究结果可对多因素叠加影响下岩石破坏诱发突水事故的研究提供参考。

Primary fissures and water bodies will change the physical and mechanical properties of rocks and easily induce geological disasters.Therefore,the instability and failure behavior of rock mass under the action of water-fracture has become one of the important research contents in the field of underground geotechnical engineering.Based on the D-P criterion,the critical conditions of fracture failure of fractured rock under different water content conditions were put forward,and the possible development and expansion of new cracks in rock under the influence of primary cracks were analyzed.The shear test of water-bearing red sandstone was carried out.The results show that within the scope of this test,the water-bearing fracture rock sample and the prefabricated primary fracture evolve in a segmented manner with a 20°angle as the boundary.With the increase of fracture dip angle,the evolution trend changes from positive correlation to negative correlation,and the shear strength of water-bearing fracture rock sample is the largest at 20°.With the increase of water content,the increment of water infiltration on the weakening degree of shear performance damage of rock samples decreases.After the water content is 1.213%,with the continuous increase of water content,the weakening degree of shear performance damage of rock samples decreases from increase to decrease.It can be seen that the weakening degree of saturated water content on the damage of fractured rock samples is less than that of unsaturated water content.The failure mode of the shear failure surface shows a trend of shear failure-shear failure dominated tensile-shear composite failure-tensile-shear composite failure-tensile failure dominated tensile-shear composite failure.The research results can provide reference for the study of water inrush accidents induced by rock failure under the influence of multiple factors.