Study On The Mechanical Characteristics Of Fully Grouted Partially Anchored Rock Bolt/Cable

For rock burst roadway with broken roof or remaining top coal,the fully grouted fully anchored support with rock bolt and cable can not only effectively control the deformation of surrounding rock,but also strengthen the broken surrounding rock.However,the fully grouted fully anchored support of tunnel is prone to local deformation and stress concentration and failure.For this reason,the fully grouted partially anchored rock bolt/cable support is put forward.In this thesis,the mechanical characteristics of the fully grouted partially anchored support of rock bolt/cable are studied by laboratory experiment and numerical simulation,and the following results are obtained:In this thesis,the weakening effect of grouting isolation layer thickness on anchoring mechanical properties of bolt（cable）is studied by laboratory experiment.The anchoring force test is carried out on the rock bolt which is not treated and wrapped with 1,2 and 5 grouting isolation layers on the surface.The maximum anchoring force is obtained as 239.68kN/m,50.49kN/m,13.76kN/m and 8.64kN/m,respectively.The anchoring force test is carried out on the cable which is not treated and wrapped with 3and 5 grouting isolation layers on the surface.The maximum anchoring force is obtained as 1330.91kN/m,278.53kN/m and 37.67kN/m,respectively.It is known that the greater the number of isolated layers wrapped by grouting on the surface of the rock bolt（cable）,the smaller the maximum anchoring force of the rock bolt（cable）.FLAC^3D numerical simulation is used to analyze the anchorage mechanical properties of single fully grouted fully anchored and fully grouted partially anchored rock bolt（cable）under static load and dynamic load respectively.Under the action of surrounding rock deformation after roadway excavation,the axial force of single fully grouted partially anchored rock bolt（cable）is less than that of fully grouted fully anchored rock bolt（cable）,which is 90.18kN（193.51kN）and 109.20kN（227.08kN）respectively.Under the action of roof crack opening and shear dislocation,the maximum displacement of single fully grouted partially anchored rock bolt（cable）is larger than that of fully grouted fully anchored rock bolt（cable）,they are 166mm（137mm）and 46mm（47mm）respectively under the action of crack opening,and they are 23mm（228mm）and 21mm（109mm）respectively under shear dislocation.Under the dynamic load of 2m/s and 5m/s after tunnel excavation,the increment of axial force of single fully grouted partially anchored rock bolt（cable）is smaller than that of fully grouted fully anchored rock bolt（cable）,and the increment under 2m/s dynamic load is1.73kN（3.21kN）and 4.59kN（6.19kN）,respectively.The increment of 5m/s under dynamic load is 5.34kN（4.68kN）and 11.75kN（6.19kN）respectively.The above results show that the mechanical properties of fully grouted partially anchored rock bolt（cable）are better than those of fully grouted fully anchored rock bolt（cable）.Based on the research background of 3^-1402 working face’s belt transport support of Hongqinghe Coal Mine,FLAC^3D simulation software is used to analyze the dynamic and static load working characteristics of fully grouted fully anchored and fully grouted partially anchored supporting system in the roadway.In the early stage of roadway excavation,the two anchoring support methods have similar control effects on surrounding rock deformation under static load and superposition of static and dynamic load.However,the axial force and deformation distribution of the fully grouted partially anchored rock bolt（cable）along the axis are more uniform than that of the fully grouted fully anchored rock bolt（cable）,and the maximum axial force of the fully grouted partially anchored rock bolt（cable）is lower than that of the fully grouted fully anchored rock bolt（cable）.The results show that the deformation and force characteristics of fully grouted partially anchored support system is better than that of fully grouted fully anchored support system.This thesis has 90 figures,17 tables and 84 references.