Research On Anchorage Performance Of Bolts And Optimization Of Roadway Supporting Scheme

As one primary reinforcement measure in underground roadway of coal mine,rock bolting has been used worldwide.Bolts supporting is active supporting method,in terms of load transfer,the bolts anchorage system is mainly composed of four parts,they include bolts,internal fixture,external fixture and surrounding rock.The mechanical properties of these elements determine the stability of the anchorage system.With the deepening of the coal seam mining,the support of the roadway is affected by the high ground stress and strong disturbing stress,resulting in large deformation and serious damage of the surrounding rock,supporting difficulty and so on.In order to improve the anchoring performance of bolts supporting and improve the effect of roadways,the research on the anchoring performance of bolts and the optimization of supporting scheme is carried out in this dissertation.In the research of bolt parameters,the load transfer mechanics model of resin bolts were established,the relationship between the spacing of anchor ribs and the failure of resin and anchorage were clarified.Based on the thick-wall theory,this dissertation put forward the laboratory test method of anchorage performance under different conditions of the surrounding rock strength.Laboratory and field tests show that bolts parameters and the strength of roadway surrounding rock have an important effect on the anchoring performance of the bolts.For left and right bolts with rib spacing of 12?48 mm under different conditions of surrounding rock,increasing rib spacing can improve the anchoring performance of the bolts.Based on the study of load transfer mechanism of internal fixture,the stress distribution law and anchorage performance analysis method of bolts body under different anchorage modes were established.Through theoretical analysis,laboratory tests and on-site monitoring,the distribution and development characteristics of axial stresses of the bolts under different anchorage modes were evaluated.It is found that point anchored bolts are subjected to the tensile force is dominant;its peak force is located near the anchorage section.For fully grouted rock bolts,the axial force is either tensile or compressive force along the bolt,the axial force distribution of fully grouted rock bolts are closely related to surrounding rock conditions,The peak point of stress is located at the edge or separation of broken surrounding rock in roadway.Field tests show that fully grouted rock bolts are more suitable for support of unevenly deformed surrounding rock.The design method of yieldable supporting device for bolting support in mining roadway is put forward,and the design criteria of yieldable supporting device parameters are formulated in the dissertation.Based on theoretical calculation,laboratory test and numerical simulation,the yielding load and distance of the yieldable supporting device for different parameters are determined,which provides a basis for the selection of the yieldable supporting device under different mine surrounding rock conditions.Based on the above research contents and results,the FLAC3D numerical simulation method was used to optimize the bolting support scheme of the mining roadway.By comparing the stress characteristics of the surrounding rock under different support schemes and the performance characteristics of each element of the anchoring system,the optimization scheme of mining roadway support were put forward.The research results were successfully applied to the+425m horizontal B3 roadway in Wudong coal mine.Based on the strength of surrounding rock,the right-handed threadless steel bolts with rib spacing of 48 mm were adopted.It can improve the anchoring performance of bolts without changing the supporting technology and engineering cost,and give full play to the bearing capacity of surrounding rock itself.According to the deformation characteristics of surrounding rock,fully grouted pre-stressed roof anchorage and fully grouted internal fixture design of large-diameter FRP bolts in mining side are adopted,which improves the control performance of surrounding rock in Anchorage system.Aiming at the large amount of elastic potential energy and displacement of the rock in the roadway,an appropriate external pressure-relief device was designed to reduce the damage of the anchoring system by improving the anchoring performance of the external fixture,eliminating the safety hazards such as uncapping.The roadway support effect increased by 12%and the cost of support materials was reduced by 13%.The dissertation systematically analyzes the effects and influences of the anchor elements in the load transfer process,clarifies the key control factors of anchoring performance,and proposes a design optimization scheme for bolting support in mining roadway based on geological conditions,which provides basic theory and technical support for safe and efficient mining.There are 126 figures,40 tables and 145 references in the dissertation.