According to the practical conditions of coal roadway in Changcun Coal Mine of Lu＇an Mining Group, the deformation of rock surrounding roadway was experimentally studied by means of thermal infrared （TIP,） imaging ...According to the practical conditions of coal roadway in Changcun Coal Mine of Lu＇an Mining Group, the deformation of rock surrounding roadway was experimentally studied by means of thermal infrared （TIP,） imaging system in the process of confined compressions. It is found that the model surface TIR temperature （TIRT） changes with the increase of load. Furthermore, TIRT changes non-synchronously in different ranges such as the roof, floor, wall, corners and bolted ranges. The TIRT is higher in the location of stress concentration and bolted ranges than that in the location of stress relaxation and broken ranges. The interaction ranges of bolt and rock are determined preliminarily according to the corresponding relationship of TIRT fields and the strain fields of the surrounding rock. The new method of TIR image processing has been proved to be effective for the study of bolt support and observation of roadway stability under mine pressure.展开更多
Accurate modelling of the potential failure modes in the rock mass is an essential task towards a robust design of roof support systems in coal mines.The use of generalised rock mass properties based on averaged prope...Accurate modelling of the potential failure modes in the rock mass is an essential task towards a robust design of roof support systems in coal mines.The use of generalised rock mass properties based on averaged properties(e.g.Hoek-Brown model) has been found to limit the capability to reproduce the actual rock mass behaviour which may include a wide range of interacting and complex failure mechanisms such as shear and tension fracturing of the intact rock and shear and separation of pre-existing discontinuities,including re-activation.Recent studies have also shown that traditional models,such as the Mohr-Coulomb,may not accurately describe the behaviour of the intact rock,particularly for stress induced failures where spalling and slabbing are observed.This is mainly due to the cohesion and friction components of the shear strength of the intact rock not being mobilised at the same rate with strain-softening of the former component playing an essential role in the post peak behaviour.In addition,coal measure rocks are often transversely isotropic,both by way of the preferred orientation of clay particles within the finer grained lithology and by bedding textures and bedding partings,and this is often ignored in computer simulations.A newly developed transversely isotropic brittle rock mass model is applied in the simulation of a hypothetical and simple roadway development.A Cohesion Weakening-Friction Strengthening(CWFS) approach is adopted to describe the intact rock where the mobilisation and strain-softening of the two shear strength components are linked to plastic deformation.The impacts of anisotropy and brittle rock on the development of the excavation disturbed zone or height of softening,as often referred to,are investigated and their implication in the roof support design discussed.展开更多
Based on references [1~3]. the mechanical models have been developed to study the presupport mechanism of forepoling bolt structure in this paper. The following problems are discussed:(1) the pre-support mechanism of ...Based on references [1~3]. the mechanical models have been developed to study the presupport mechanism of forepoling bolt structure in this paper. The following problems are discussed:(1) the pre-support mechanism of forepoling bolt structure and stress distribution on its upper broken rock; (2) loading state of forepoling bolt; (3 ) solution of arching in the cross section of excavation.展开更多
基金Projects 50374069 supported by National Natural Science Foundation of China and 2002CB412701 supported by 973 of China
文摘According to the practical conditions of coal roadway in Changcun Coal Mine of Lu＇an Mining Group, the deformation of rock surrounding roadway was experimentally studied by means of thermal infrared （TIP,） imaging system in the process of confined compressions. It is found that the model surface TIR temperature （TIRT） changes with the increase of load. Furthermore, TIRT changes non-synchronously in different ranges such as the roof, floor, wall, corners and bolted ranges. The TIRT is higher in the location of stress concentration and bolted ranges than that in the location of stress relaxation and broken ranges. The interaction ranges of bolt and rock are determined preliminarily according to the corresponding relationship of TIRT fields and the strain fields of the surrounding rock. The new method of TIR image processing has been proved to be effective for the study of bolt support and observation of roadway stability under mine pressure.
基金Project support from the Specialist Technical Apprentice Scheme from Coffey Geotechnics Ltd. Pty
文摘Accurate modelling of the potential failure modes in the rock mass is an essential task towards a robust design of roof support systems in coal mines.The use of generalised rock mass properties based on averaged properties(e.g.Hoek-Brown model) has been found to limit the capability to reproduce the actual rock mass behaviour which may include a wide range of interacting and complex failure mechanisms such as shear and tension fracturing of the intact rock and shear and separation of pre-existing discontinuities,including re-activation.Recent studies have also shown that traditional models,such as the Mohr-Coulomb,may not accurately describe the behaviour of the intact rock,particularly for stress induced failures where spalling and slabbing are observed.This is mainly due to the cohesion and friction components of the shear strength of the intact rock not being mobilised at the same rate with strain-softening of the former component playing an essential role in the post peak behaviour.In addition,coal measure rocks are often transversely isotropic,both by way of the preferred orientation of clay particles within the finer grained lithology and by bedding textures and bedding partings,and this is often ignored in computer simulations.A newly developed transversely isotropic brittle rock mass model is applied in the simulation of a hypothetical and simple roadway development.A Cohesion Weakening-Friction Strengthening(CWFS) approach is adopted to describe the intact rock where the mobilisation and strain-softening of the two shear strength components are linked to plastic deformation.The impacts of anisotropy and brittle rock on the development of the excavation disturbed zone or height of softening,as often referred to,are investigated and their implication in the roof support design discussed.
文摘Based on references [1~3]. the mechanical models have been developed to study the presupport mechanism of forepoling bolt structure in this paper. The following problems are discussed:(1) the pre-support mechanism of forepoling bolt structure and stress distribution on its upper broken rock; (2) loading state of forepoling bolt; (3 ) solution of arching in the cross section of excavation.
