Experiments simulating the effect of coal mine stopping through a fault zone were designed based on a working face of the Qianqiu coal mine in Yima, China. Through simulation of the physical process of fault reactivat...Experiments simulating the effect of coal mine stopping through a fault zone were designed based on a working face of the Qianqiu coal mine in Yima, China. Through simulation of the physical process of fault reactivation and coal bumps, the displacement of the surrounding strata and evolution characteristics of fault stress under the effect of mining were studied. The mechanism of fault reactivation induced by coal mining was analyzed. The results show that shortly before fault reactiva- tion, the normal stress and shear stress increased rapidly and the risk of a fault slip occurring was also increased. The fault reac- tivation, caused by the mining activity, occurred when the working face was 25-35 m from the fault along the hanging wall. The influence of mining increased the possibility of fault reactivation, while the local failure of the bearing capacity of the working face was the direct cause of the fault slip. Our results indicate that the influence of fault slip on the coal of the working face had a transient impact and acted as a loading-unloading function.展开更多
This paper proposes a method for creating a three-dimensional(above-ground and underground)fracture network in deep coalbed methane(CBM)reservoirs,which is the directional fracturing by slotted hydraulic blasting in u...This paper proposes a method for creating a three-dimensional(above-ground and underground)fracture network in deep coalbed methane(CBM)reservoirs,which is the directional fracturing by slotted hydraulic blasting in underground drilling.First,theoretical analysis was conducted to explain the mechanism by which the slotted borehole enables the separation and incidence of explosive shock wave at the slot tip,resulting in the superposition of two sub-stress waves to cause directional fracture and damage to the rock.Then,LS-DYNA was used to simulate the process of directional fracturing by slotted hydraulic blasting to verify the theoretical mechanism.Finally,similar simulation experiments were performed on traditional blasting and slotted hydraulic blasting to confirm the directional fracturing effect of the proposed method.The results indicate that the slotted hydraulic blasting method can predominate the fracture orientation under formation stress,creating extensive directional fractures in rocks in the slot direction.This study is supplemental to the efforts on directional fracturing of rocks and provides a new approach for efficient exploitation of CBM.展开更多
This study employs similar simulation testing and discrete element simulation coupling to analyze the failure and deformation processes of a model coal seam's roof.The caving area of the overburden rock is divided...This study employs similar simulation testing and discrete element simulation coupling to analyze the failure and deformation processes of a model coal seam's roof.The caving area of the overburden rock is divided into three zones:the delamination fracture zone,broken fracture zone,and compaction zone.The caving and fracture zones'heights are approximately 110 m above the coal seam,with a maximum subsidence of 11 m.The delamination fracture zone's porosity range is between 0.2 and 0.3,while the remainder of the roof predominantly exhibits a porosity of less than 0.1.In addition,the numerical model's stress analysis revealed that the overburden rock's displacement zone forms an'arch-beam'structure starting from 160 m,with the maximum and minimum stress values decreasing as the distance of advancement increases.In the stress beam interval of the overburden rock,the maximum value changes periodically as the advancement distance increases.Based on a comparative analysis between observable data from on-site work and numerical simulation results,the stress data from the numerical simulation are essentially consistent with the actual results detected on-site,indicating the validity of the numerical simulation results.展开更多
基金Supported by the Major State Basic Research Development Program Fund （2010CB226801） the National Natural Science Foundation of China （50704034） the State Key Laboratory of Coal Resources and Safe Mining Open Research Fund （SKLCRSM11KFB08）
文摘Experiments simulating the effect of coal mine stopping through a fault zone were designed based on a working face of the Qianqiu coal mine in Yima, China. Through simulation of the physical process of fault reactivation and coal bumps, the displacement of the surrounding strata and evolution characteristics of fault stress under the effect of mining were studied. The mechanism of fault reactivation induced by coal mining was analyzed. The results show that shortly before fault reactiva- tion, the normal stress and shear stress increased rapidly and the risk of a fault slip occurring was also increased. The fault reac- tivation, caused by the mining activity, occurred when the working face was 25-35 m from the fault along the hanging wall. The influence of mining increased the possibility of fault reactivation, while the local failure of the bearing capacity of the working face was the direct cause of the fault slip. Our results indicate that the influence of fault slip on the coal of the working face had a transient impact and acted as a loading-unloading function.
基金supported by the Science and Technology Department of Guizhou Province Fund(Qiankehe Basic-ZK[2023]Normal-446 and Qiankehe Basic-ZK[2023]Normal-445)Liupanshui Science and Technology Bureau Fund(52020-2022-PT-15)the Education Department of Guizhou Province Fund(Youth Science and Technology Talent Development Project Qianjiaoji[2024]150).
文摘This paper proposes a method for creating a three-dimensional(above-ground and underground)fracture network in deep coalbed methane(CBM)reservoirs,which is the directional fracturing by slotted hydraulic blasting in underground drilling.First,theoretical analysis was conducted to explain the mechanism by which the slotted borehole enables the separation and incidence of explosive shock wave at the slot tip,resulting in the superposition of two sub-stress waves to cause directional fracture and damage to the rock.Then,LS-DYNA was used to simulate the process of directional fracturing by slotted hydraulic blasting to verify the theoretical mechanism.Finally,similar simulation experiments were performed on traditional blasting and slotted hydraulic blasting to confirm the directional fracturing effect of the proposed method.The results indicate that the slotted hydraulic blasting method can predominate the fracture orientation under formation stress,creating extensive directional fractures in rocks in the slot direction.This study is supplemental to the efforts on directional fracturing of rocks and provides a new approach for efficient exploitation of CBM.
基金National Key R&D Program of China(2023YFC3009100,2023YFC3009102)National Natural Science Foundation of China(52304198)Open Fund of the National and Local Joint Engineering Research Center for Safe and Accurate Coal Mining(EC2021016).
文摘This study employs similar simulation testing and discrete element simulation coupling to analyze the failure and deformation processes of a model coal seam's roof.The caving area of the overburden rock is divided into three zones:the delamination fracture zone,broken fracture zone,and compaction zone.The caving and fracture zones'heights are approximately 110 m above the coal seam,with a maximum subsidence of 11 m.The delamination fracture zone's porosity range is between 0.2 and 0.3,while the remainder of the roof predominantly exhibits a porosity of less than 0.1.In addition,the numerical model's stress analysis revealed that the overburden rock's displacement zone forms an'arch-beam'structure starting from 160 m,with the maximum and minimum stress values decreasing as the distance of advancement increases.In the stress beam interval of the overburden rock,the maximum value changes periodically as the advancement distance increases.Based on a comparative analysis between observable data from on-site work and numerical simulation results,the stress data from the numerical simulation are essentially consistent with the actual results detected on-site,indicating the validity of the numerical simulation results.
