Study On Mechanical Properties Of Rock Mass Structural Plane Under High Temperature And Chemical Corrosion

tructural plane is an important part of rock mass,which can control the mechanical properties of rock mass.In the actual construction of rock mass engineering,rock mass is often affected by special environment,such as high temperature and chemical corrosion.The environmental action will cause the change of mineral composition and structure of rock mass,greatly weaken the overall strength of rock mass,and lead to the decrease of rock mass engineering stability.Therefore,it is of great engineering value and academic significance to study the mechanical properties of structural planes under high temperature and chemical corrosion.In this paper,cement mortar structural plane specimens and sandstone structural plane specimens are selected as the research objects.The shear tests of structural planes under high temperature and chemical corrosion are carried out respectively,and the damage mechanism is analyzed.Finally,the test simulation under special environment is carried out by 3DEC discrete element software.The test data are compared with the simulation data to verify the rationality of the parameters.Finally,the verified parameters are applied to the stability analysis of jointed tunnels.The specific research contents are as follows :(1)Firstly,the equipment function characteristics and operation process of the three-dimensional topography laser tester of rock structural plane independently developed by our research group are introduced in detail.Then,it is determined that the joints selected in the numerical simulation of this paper are the discrete fracture network(DFN)model and the joint constitutive is the continuous yield joint model.The parameters of the continuous yield joint model and its determination method are described,which provides a theoretical basis for the parameter selection of the numerical simulation.(2)The three-dimensional morphology parameters of cement mortar structural plane were obtained by means of the three-dimensional morphology laser tester independently developed by the research group.The shear test of structural plane specimens after different high temperatures was carried out.The influence of high temperature on the shear stress and shear displacement of structural plane was analyzed,and the damage mechanism of high temperature on structural plane was revealed.At the same time,the influence of high temperature on the three-dimensional morphology of the structural plane is analyzed,and the relationship that can reflect the influence of high temperature on the compressive strength of the structural plane is constructed.(3)The three-dimensional shape parameters of sandstone structural plane were obtained by three-dimensional shape laser tester,and the shear test of sandstone structural plane under chemical corrosion was carried out.The influence of chemical corrosion on the three-dimensional morphology parameters and permeability of the structural plane was analyzed,and the damage mechanism of chemical corrosion on the structural plane was explored.The damage parameters are introduced to describe the deterioration law of shear strength of structural plane after chemical corrosion,and the relationship between shear strength and chemical corrosion and roughness coefficient is established.(4)On the basis of the above research,the parameters of the structural plane specimens are determined.The shear and seepage tests of structural plane under special environment are simulated by 3DEC,and the test data are compared with the simulation data to verify the rationality of the model and parameters.Finally,the joint parameters in different environments are applied to the stability analysis of Qingdao tunnel,and the influence of temperature,chemical solution,corrosion time and permeability coefficient on tunnel stability is analyzed.