Experimental And Particle Flow Simulation Study Of Mechanical Properties Of Laminated Rocks Under Anchoring Action

Laminated rock is a kind of rock that exists commonly in nature.In the central and western mountainous areas of China,there are widely distributed laminated rocks with obvious laminated structure,laminated fissure and softening and deformation by water,such as shale,slate and kilometre rock strata.Under the influence of long geological evolution and complex ground stress,due to geological structure,magma action,gravity action,convection action and other factors,some geological layers have formed laminated structure through sedimentation or metamorphism,while a large number of discontinuous micro-defects are contained inside.Under the long-term effect of loading,the internal damage of the laminated rock develops continuously.In addition,the dip angle,interface properties and support form also have a significant impact on the performance of laminated rock masses,so the mechanical properties,deformation and damage characteristics of these rock masses are relatively complex.These problems make the rock formation easy to be damaged during the construction process,which leads to engineering accidents.Therefore,in practical engineering,for laminated rocks with complex properties,it is necessary to determine their mechanical parameters and select scientific and suitable solutions for reinforcement and support of laminated rocks according to the material and load,in order to ensure the stability of laminated rocks and the safety of engineering production.In this paper,red sandstone is selected as the research object,and the laminated rock is made artificially by setting four laminar dip angles of 0°,30°,60° and 90°,and some specimens are treated with anchoring,and physical property tests of uniaxial compression test and Brazilian splitting test are carried out to test the strength and damage morphology of unanchored and anchored specimens.Based on the experimental results,the crack extension process of the laminated rocks are simulated and analyzed by using granular flow software.The main research contents are as follows.(1)Material design of rocks with different anchoring conditions and specimen fabrication are carried out.Raw rock collection is carried out,and the rock is drilled,cut,and bonded to produce laminated rock samples suitable for uniaxial compression and Brazilian splitting;anchoring materials are designed with reference to relevant literature,and the rocks are drilled with a drilling machine,screws are installed,and the laminated rocks are anchored and numbered in preparation for subsequent experiments.(2)The compressive performance tests of laminated rocks under different anchorage conditions are carried out,and the physical and mechanical parameters and fracture patterns of uniaxial compression of unanchored specimens and specimens with different pretensions and different anchorage angles are analyzed,and conclusions are drawn on the strengthening effect and fracture stopping effect of anchored laminated rocks under different anchorage conditions.(3)The tensile properties of laminated rocks under different anchorage conditions are tested,and the physical and mechanical parameters and rupture patterns of unanchored specimens and specimens with different preload and different anchorage angles are analyzed in the Brazilian splitting test,and conclusions are drawn on the strengthening effect and the fracture stopping effect of anchored laminated rocks under different anchorage conditions.(4)Based on the experimental results,the PFC2 D particle flow simulation software is used to establish a simulation model of rock specimens with different laminar angles and different anchorage conditions,and a set of PFC2 D fine parameters reflecting the macroscopic mechanical properties of the actual test is debugged on the basis of sensitivity analysis of the laminar fine parameters.The deformation and damage mechanism of the laminated rock is analyzed.