Irregular shape workface would result in the presence of coal pillar, which leads to high stress concentration and possibly induces coal bumps. In order to study the coal bump mechanism of pillars, static and dynamic ...Irregular shape workface would result in the presence of coal pillar, which leads to high stress concentration and possibly induces coal bumps. In order to study the coal bump mechanism of pillars, static and dynamic stress overlapping(SDSO) method was proposed to explain the impacts of static stress concentration and tremors induced by mining activities. The stress and deformation in surrounding rock of mining face were analyzed based on the field case study at 1303 workface in Zhaolou Coal Mine in China.The results illustrate that the surrounding rock of a workface could be divided into four different zones,i.e., residual stress zone, stress decrease zone, stress increase zone and original stress zone. The stress increase zone is prone to failure under the SDSO impact loading conditions and will provide elastic energy for inducing coal bump. Based on the numerical modelling results, the evolution of static stress in coal pillar as the size of gob increasing was studied, and the impact of dynamic stress was investigated through analyzing the characteristics of tremor activities. The numerical results demonstrate the peak value of vertical stress in coal pillar rises from about 30 MPa with mining distance 10 m to 52.6 MPa with mining distance 120 m, and the location of peak stress transfers to the inner zone of coal pillars as the workface moves forward. For the daily tremor activities, tremors with high energy released indicate high dynamic stress disturbance on the surrounding rock, therefore, the impact of dynamic stressing is more serious during workface extension period because the tremor frequency and average energy after workface extension are higher than those before the workface extension.展开更多
开挖面失稳坍塌是隧道施工安全的重大威胁之一,合理设计隧道开挖面极限支护压力和预测开挖面失稳破坏影响范围是隧道施工安全的保障。采用自编隐式物质点法(Material Point Method,MPM)程序对隧道开挖面失稳机制进行研究。首先通过理论...开挖面失稳坍塌是隧道施工安全的重大威胁之一,合理设计隧道开挖面极限支护压力和预测开挖面失稳破坏影响范围是隧道施工安全的保障。采用自编隐式物质点法(Material Point Method,MPM)程序对隧道开挖面失稳机制进行研究。首先通过理论和试验对比,验证了隐式MPM模拟开挖面稳定性的可行性。随后建立工程尺度的隧道模型,分析土体摩擦角对隧道开挖面坍塌和地层变形响应的影响。结果表明:(1)隐式MPM可有效捕捉掌子面失稳-破坏全过程特征;(2)在临界状态下,隧道掌子面的极限支护力、失稳区域和地表沉降均随土体摩擦角的增加呈负相关关系;(3)当隧道掌子面发生倒塌破坏时,涌入隧道的土体质量与土体摩擦角呈负相关关系。展开更多
基金financially supported by National Science and Technology Key Project Fund of China (Nos.2016YFC0801401 and 2016YFC0600708)Fundamental Research Funds for the Central Universities of China (No.2009QM01)Yue Qi Distinguished Scholar Project,China University of Mining & Technology,Beijing,China
文摘Irregular shape workface would result in the presence of coal pillar, which leads to high stress concentration and possibly induces coal bumps. In order to study the coal bump mechanism of pillars, static and dynamic stress overlapping(SDSO) method was proposed to explain the impacts of static stress concentration and tremors induced by mining activities. The stress and deformation in surrounding rock of mining face were analyzed based on the field case study at 1303 workface in Zhaolou Coal Mine in China.The results illustrate that the surrounding rock of a workface could be divided into four different zones,i.e., residual stress zone, stress decrease zone, stress increase zone and original stress zone. The stress increase zone is prone to failure under the SDSO impact loading conditions and will provide elastic energy for inducing coal bump. Based on the numerical modelling results, the evolution of static stress in coal pillar as the size of gob increasing was studied, and the impact of dynamic stress was investigated through analyzing the characteristics of tremor activities. The numerical results demonstrate the peak value of vertical stress in coal pillar rises from about 30 MPa with mining distance 10 m to 52.6 MPa with mining distance 120 m, and the location of peak stress transfers to the inner zone of coal pillars as the workface moves forward. For the daily tremor activities, tremors with high energy released indicate high dynamic stress disturbance on the surrounding rock, therefore, the impact of dynamic stressing is more serious during workface extension period because the tremor frequency and average energy after workface extension are higher than those before the workface extension.
文摘开挖面失稳坍塌是隧道施工安全的重大威胁之一,合理设计隧道开挖面极限支护压力和预测开挖面失稳破坏影响范围是隧道施工安全的保障。采用自编隐式物质点法(Material Point Method,MPM)程序对隧道开挖面失稳机制进行研究。首先通过理论和试验对比,验证了隐式MPM模拟开挖面稳定性的可行性。随后建立工程尺度的隧道模型,分析土体摩擦角对隧道开挖面坍塌和地层变形响应的影响。结果表明:(1)隐式MPM可有效捕捉掌子面失稳-破坏全过程特征;(2)在临界状态下,隧道掌子面的极限支护力、失稳区域和地表沉降均随土体摩擦角的增加呈负相关关系;(3)当隧道掌子面发生倒塌破坏时,涌入隧道的土体质量与土体摩擦角呈负相关关系。
