| Layered rock mass is a product of stratum deposition and formation,and it is widely distributed in the world.The excavation and unloading of the roadway destroys the stress balance state in the layered surrounding rock of the original roadway,and the stress redistributes in the surrounding rock in a concentrated manner.Under the influence of mining and mechanical disturbance,the layered surrounding rocks are relatively dislocated,and the surrounding rocks are prone to be damaged by shear slip,which brings challenges to roadway support.As the weak point of the layered surrounding rock structure,the bedding direction and bedding shape have a great influence on the shear-slip temporal and spatial progressive failure response of the surrounding rock.It is of great significance to study the shear mechanical properties,deformation instability characteristics and anchoring mechanism of layered jointed rock mass for the stability control of roadway surrounding rock.Therefore,in order to comprehensively explore the shear mechanical properties and anchoring mechanism of layered jointed rock mass,rock-like samples of layered rock mass with different bedding dip angles and bedding roughness were produced,and the macroscopic shear characteristics and microscopic damage evolution characteristics of layered rock mass are explored from the perspective of the indoor direct shear tests and particle flow simulation.In addition,the shear reinforcement effect of the anchor was explored by the simulation of the bolted layered rock mass under shearing,and the damage evolution,the stress state of the anchor and the anchoring mechanism of the anchor under shearing were revealed.The research results obtained mainly include the following aspects:（1）Based on 3D printing technology,the templates for pouring layered matrices with different bedding roughnesses were designed and manufactured.The rock-like materials of cement and fly ash were used to cast layered matrices with different Barton standard roughness bedding forms according to the mix ratio.The rock matrices were bonded with low-strength cement grout and cut and polished to obtain layered rock mass rock samples with 5 kinds of bedding roughness and 5 kinds of bedding dip angles.（2）Indoor direct shear tests on layered samples with different bedding dip angles and different bedding roughnesses under four kinds of constant normal stresses were carried out.Using digital photography measurement and acoustic emission technology as the main monitoring methods,the shear mechanical properties,ductile damage characteristics,acoustic emission ringing evolution,crack spatial distribution,strain field evolution and failure mode distribution characteristics of layered rock mass under shearing were explored.（3）The particle flow numerical model of layered rough jointed rock mass under direct shearing was established by using discrete element simulation software PFC2D.The evolution of slip energy and strain energy,the spatial and temporal evolution of cracks,the distribution characteristics of displacement field and force chain contact fabric in the shear process of unanchored layered rock mass were revealed,which provided a mesoscopic explanation for the shear ductility damage characteristics,macroscopic failure mode,crack direction and distribution of layered rock mass.（4）The numerical models of direct shear particle flow of layered rock anchorage body under different anchorage conditions were established.Based on the shear mechanical response and micro crack distribution characteristics,the shear reinforcement effect of bolt was explored.By analyzing the crack propagation,displacement field and force chain field distribution in the shear process,the damage evolution and anchorage mechanism of anchorage body under shear action were explored.The stress evolution law of bolt in the shear process was obtained by arranging and updating the measurement circle position.Based on the stress state of bolt under the shear action,the support member of Anti-shear rise resistance anchor cable was designed,the support scheme was improved and good support effect was obtained.There are 81 figures,12 tables,and 95 references in this thesis. |
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