Evolution Behaviours Of Crack At Bedding Plan In Layered Rocks

With the rapid development of China's economy and technology,large-scale infrastructure construction is in full swing in recent years.Tunnels and underground space projects built in layered rock masses are constantly emerging,and the mechanism of the evolution of layered rock mass fissures has become an urgent need.Scientific issues.Because the layered rock mass in natural state is difficult to obtain and process,this paper adopts the layered rock mass rock sample instead of the layered rock mass for experimental research.The test was carried out under splitting conditions,and the numerical software PFC was used to investigate the extended evolution characteristics of the layered rock mass fissures on the bedding plane.The main research contents of this paper are as follows:(1)Determine the material mix ratio.The test uses ordinary Portland cement,river sand and tap water to cast layered rock mass rock samples according to the mixing ratio.The compressive strength and tensile strength of the materials were determined by uniaxial compression and Brazilian splitting,and the mechanical properties of shale and layered rock samples were compared.The test plan is designed with six types of bedding angles and three types of pre-formed fissures.The splitting test is carried out on the rock samples of the layered rock mass,and the extension process of the surface crack of the sample and the load-displacement curve of the sample are recorded for further analysis.The influence of the different lamelge angles and preset crack locations on the failure results of layered rock mass under splitting conditions.(2)Based on the experiment,the particle flow numerical software-PFC2 D is used to simulate the evolution of the layered rock mass on the bedding plane.Since the microscopic parameters of the model are not directly related to the macroscopic phenomena of the test,the calibration experiment is first carried out,and the macroscopic and microscopic mapping links are established.The purpose of the calibration test is to determine the mesoscopic parameters.The macroscopic results of the evolution characteristics of the layered rock mass cracks in the bedding plane can be explained by the model mesoscopic parameters.(3)Contrast test and simulation results,the influence of the lamellar angle and prefracture position on the evolution and evolution of the layered rock mass on the bedding plane is investigated,and the evolution process of the lamellar rock mass in the bedding plane is recorded.And the model constitutes the evolution path of the particle displacement field,and deeply explores the influence of confining pressure on the expansion and evolution of the layered rock mass in the bedding plane.