Undercut is one kind of important spaces to place the mining blocks in the mass underground mining. This structure is also used as a compensation space during blasting. In the process of underground mining in the frag...Undercut is one kind of important spaces to place the mining blocks in the mass underground mining. This structure is also used as a compensation space during blasting. In the process of underground mining in the fragment orebody, it is important and critical to analyze the stability and blockage of the three-dimensional wedges created around the undercut space. The wedge stability is mainly controlled by factors including geometry （i.e., the size, shape and spatial location of the wedge and undercut）, the strength （shear and tensile） of the discontinuities that created the wedge, and the stress distribution within the rock mass. The Unwedge software was used to conduct the orthogonal simulation tests （three factors and five levels） that considered different cross sections, trends, and plunges of the undercut space. The results demonstrate that the control value of the safety factor of wedge is set to be 1.2. The optimal parameters are determined in the undercut space, such as the blasting fragmentation, orientation of the fluid flow, and the equipment gradeability;the wedge stability can be evaluated in the light of the block images and continuous falling;the stability of the key block meets the needs of the undercut space, the parameters gained are reasonable and optimal. Cross section is 27°, trend is from 315°to 325°（it is 320°at in-suit test） and plunge is 5°.展开更多
Evaluation of the performance of existing support in underground tunnels is of great importance for production and interests.Based on field investigation,the shape and number of joints and fractures were investigated ...Evaluation of the performance of existing support in underground tunnels is of great importance for production and interests.Based on field investigation,the shape and number of joints and fractures were investigated in the mining area.Then,the stability of each structural blocks is analyzed by 3D wedge stability analysis software(Unwedge).Moreover,a new analysis method based on critical block theory is applied to analyze the stability of excavated laneways in continuous and discontinuous rock and monitor the stress changes in a fractured tunnel rock mass.The test results indicate that the 3D wedge stability analysis software for underground excavation can evaluate deep tunnel support.Besides,there is no direct relation between the size of the block and the instability of the tunnel.The support method,on large and thick key blocks,needs to be improved.In a broken tunnel section,U-shaped steel support can effectively promote the stress state of the surrounding rock.By monitoring the surrounding rock,it is proven that the vibrating string anchor stress monitoring system is an efficient and real-time method for tunnel stability evaluation.展开更多
基金Project(2015CX005)supported by Innovation Driven Plan of Central South University,ChinaProject(2016zzts451)supported by the Graduate Innovation Fund of Central South University,China+1 种基金Project(2016JJ21)supported by the Fundamental Research Funds for the Hunan Province,ChinaProject(2012BAB14B01)supported by the National Science and Technology Pillar Program during the 12th Five-year Plan Period of China
文摘Undercut is one kind of important spaces to place the mining blocks in the mass underground mining. This structure is also used as a compensation space during blasting. In the process of underground mining in the fragment orebody, it is important and critical to analyze the stability and blockage of the three-dimensional wedges created around the undercut space. The wedge stability is mainly controlled by factors including geometry （i.e., the size, shape and spatial location of the wedge and undercut）, the strength （shear and tensile） of the discontinuities that created the wedge, and the stress distribution within the rock mass. The Unwedge software was used to conduct the orthogonal simulation tests （three factors and five levels） that considered different cross sections, trends, and plunges of the undercut space. The results demonstrate that the control value of the safety factor of wedge is set to be 1.2. The optimal parameters are determined in the undercut space, such as the blasting fragmentation, orientation of the fluid flow, and the equipment gradeability;the wedge stability can be evaluated in the light of the block images and continuous falling;the stability of the key block meets the needs of the undercut space, the parameters gained are reasonable and optimal. Cross section is 27°, trend is from 315°to 325°（it is 320°at in-suit test） and plunge is 5°.
基金Projects(51964007,51774101)supported by the National Natural Science Foundation of ChinaProject(2016-4011)supported by the High-level Innovative Talents Training Project in Guizhou Province,ChinaProject(2019-5619)supported by the Guizhou Mining Power Disaster Early Warning and Control Technology Innovation Team,China。
文摘Evaluation of the performance of existing support in underground tunnels is of great importance for production and interests.Based on field investigation,the shape and number of joints and fractures were investigated in the mining area.Then,the stability of each structural blocks is analyzed by 3D wedge stability analysis software(Unwedge).Moreover,a new analysis method based on critical block theory is applied to analyze the stability of excavated laneways in continuous and discontinuous rock and monitor the stress changes in a fractured tunnel rock mass.The test results indicate that the 3D wedge stability analysis software for underground excavation can evaluate deep tunnel support.Besides,there is no direct relation between the size of the block and the instability of the tunnel.The support method,on large and thick key blocks,needs to be improved.In a broken tunnel section,U-shaped steel support can effectively promote the stress state of the surrounding rock.By monitoring the surrounding rock,it is proven that the vibrating string anchor stress monitoring system is an efficient and real-time method for tunnel stability evaluation.
