| It is a common method in engineering to reinforce rock and soil with anchor bolt.To improve the working efficiency of supporting structure and save engineering materials is the direction of scientific development of geotechnical engineering.In the process of rock and soil anchoring support,the linear anchor bolt is added into layered rock mass at different angles,resulting in different contribution of the anchor action to the stiffness and strength of rock mass in all directions,showing the characteristics of orthotropic.On the basis of summarizing a large number of scholars’research on the direction of bolt anchoring,this paper studies the"anchor solid"formed by bolt rock mass as a whole,highlights the group anchoring effect of systematic bolt,and discusses the anchoring efficiency of bolt through the mechanical effect caused by the change of angle between bolt and layered rock mass.The main work of this paper is as follows:(1)The influence of anchoring angle on the elastic modulus,Poisson’s ratio,compressive strength,peak strain,failure mode,acoustic emission energy and vibration bell count of the rock mass with anchoring angle is studied.The elastic modulus,compressive strength and peak strain with anchoring are obtained The results show that the angle increases,the crack changes gradually from shear crack to vertical crack,and the time of strain is delayed.(2)Based on the viewpoint and research method of composite mechanics,considering the different contribution of anchor to the stiffness and strength of layered rock mass in all directions,the anchored layered rock mass is regarded as a fiber-reinforced composite material with orthotropic characteristics.Based on the derivation of mechanical theory,the expressions of 9 elastic constants on three symmetrical planes are obtained,and the variation laws of elastic modulus,shear modulus and Poisson’s ratio in all directions with the increase of anchor angle are studied.The correctness of the expressions is verified by the test results.(3)Based on the orthotropic model,the indoor uniaxial compression test is simulated by FLAC3D software,and the test results are consistent with the simulation results.Considering the anti sliding effect of bolt layer,the optimal anchoring angle of bolt is 45°+φ_j/2-α,and the optimal anchoring principle of slope under different stress conditions and different parts is given.(4)The conclusion of this paper is applied to the numerical simulation calculation of layered rock slope support.Under the same use of anchor bolt,the slope stability is significantly improved and the anchor bolt anchoring efficiency is optimized.In this paper,indoor test,theoretical derivation and numerical simulation are used to study the optimal anchorage angle of the slope strengthened by anchor bolts,and the principle of anchor arrangement in different parts is put forward,which can provide theoretical basis for similar engineering design and construction. |
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