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The failure of high-positioned rock slope often occurs in alpine and gorge regions of southwest China, resulting in huge casualties and economic and property losses. At present, there are many research theories and physical models for rock landslides, but these theories and models ignore the structural characteristics of rock mass. However, for rockslides, the structural characteristics of rock mass not only control the failure mode of slope deformation, but also affect the fragmentation process of landslide after failure, and even the final hazard range. In this study the discrete element numerical simulation method is used to simulate the fragmentation process of rockslides under different strength of joint, densities of joint, directions of joint and strength of rock mass, and to examine the influence law and mechanism of joint and rock mass characteristics on rockslides fragment characteristics, propagation type and runout. The results show that (1) the horizontal runout of the center of mass increases with the increasing strength of the structural plane, the tensile strength of the structural plane increases by 10 times, and the horizontal runout of the center of mass increases by 3%. (2) The increase of the joint density increases the relative breakage ratio of blocks, but the runout and accumulation area show a downward trend. (3) Compared with other conditions, the runout of mass in the thin bedded rock sheared by the horizontal joint is reduced by about 10%, and the accumulation area is reduced by nearly 30%. (4) The block strength increases, the relative breakage ratio of blocks decreases, and the accumulation area is eventually reduced by 40%. When the block is intact, the runout eventually increases by about 15%. This research is helpful to further understand the fragmentation process of rock landslides and guide disaster prevention and mitigation in mountainous areas.

Copyright of Journal of Mine Automation is the property of Industry & Mine Automation Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Hydrogeology & Engineering Geology / Shuiwendizhi Gongchengdizhi is the property of Hydrogeology & Engineering Geology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Investigation & Surveying is the property of Railway Investigation & Surveying Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natural Gas Geoscience is the property of Natural Gas Geoscience and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tunnel Construction / Suidao Jianshe (Zhong-Yingwen Ban) is the property of Tunnel Construction Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The direct cause of pile sliding is that the sum of pile side resistance and end resistance is less than the weight of pile hammer system, which leads to the phenomenon of pile sliding during the rock socketed construction. The stress state of the pile will be changed after the drilling in the pile during rock socketed construction, the hollowing of the soil inside the pile makes the inner friction resistance disappear, and the hollowing of the soil below the pile bottom makes the tip resistance of the pile decrease. In addition, the instability of drill hole after drilling will also lead to the collapse of the soil outside the pile, resulting in the reduction of the external friction of the pile. Starting from the research on the pile sliding mechanism of largediameter single-pile rock-socketed construction of offshore wind power, the influencing factors of the pile sliding in the rocksocketed construction were analyzed. The method to deal with the problem of slipping piles in rock-socketed construction was presented. The research results can provide technical support for the construction of large-diameter single pile rock-socketed in offshore wind power in the future. [ABSTRACT FROM AUTHOR]

The coal wall and floor of the longwall face in the steeply inclined coal seam are prone to damage, which seriously affects the advance of the working face.By establishing theoretical model, bottom friction experiments, numerical calculations, etc., the characteristics of coal seam roof breaking and caving rock sliding are studied, and the coal wall failure mechanism under different coal seam occurrence and mining conditions is revealed. The concrete measures to prevent coal wall damage and floor slip are put forward.The study shows that the caving rock from the roof of the longwall face in steeply inclined coal seams will form different degrees of filling in the goaf. From bottom to top, it forms three sections including "compact filling section", "uneven filling section"and "non-filling section".However, due to insufficient filling in the upper part of the working face, the dynamic pressure phenomenon is obvious, which is likely to cause serious coal wall slab and bottom plate slip phenomenon, and the working condition of the support will also become worse, which becomes the most unstable surrounding rock of the whole working face.The fragile area seriously affects the safe and efficient production of the working face, and is the key area for the surrounding rock control of the working face.The stability of the working floor is significantly affected by the stability of the coal wall.In actual production, it is found that when the coal seam occurrence and mining conditions are different, the coal wall failure generally presents three failure modes: "plastic-flow", "extrusion-slip"and "shear-slip".The use of a pseudo-tilt arrangement at the working face not only can significantly improve the stability of the coal wall and the bottom plate, but also effectively prevent the hydraulic support from falling and sliding, and can also avoid the occurrence of flying gangue at the working face.With the integration of conveyor and the "flexible reinforced coal wall", it is possible to realize the safe and efficient mining of longwall working face in steep coal seam, and effectively solve a series of rock formation control problems faced by the mechanized mining of steep coal seam. [ABSTRACT FROM AUTHOR]

Rock burst mitigation and monitoring is a challenge during deep coal mining. Theoretical analysis, numerical simulation, laboratory tests and field monitoring are all used for researching this issue. First, the occurrence mechanisms of three types of rock burst(i. e. , strain rock burst, fault slip rock burst and hard roof rock burst) are researched. Second, two new burst liability indexes are proposed to improve the evaluation system of burst liability, which makes theburst liability evaluation system more suitable for deep coal mining. Third, the precursor information characteristics of the three rock burst types are given. Forth, the corresponding monitoring-warning and combined pressure relief methods are proposed. At last, synchronization technique of drilling and monitoring is developed. Main conclusions are as follows:(1) Deep strain rock burst is the result that the energy accumulation of surrounding rock system is larger than that of superposition of energy release and energy dissipation. Compared with shallow mining, the released energy of deep hard roof fracturing increases and deep fault slips more easily. (2) When evaluating burst liability of deep strain rock burst and hard roof rock burst, burst energy speed indexes of unloading confining pressure and combined coal-rock need to be added except the national standard, respectively. For deep fault slip rock burst, the two new indexes are all need to be added. (3) Monitoring and warning of deep strain rock burst and deep hard rock burst should depend on energy and stress criteria, while for deep fault slip rock burst, energy criterion is the priority. (4) Priorities for mitigating deep strain rock burst are protective seam mining, large-diameter drilling, floor fracturing and water infusion. Priorities for hard roof rock burst are protective seam mining, roof fracturing, large-diameter drilling, floor fracturing and water infusion. Priorities for fault slip rock burst are protective seam mining, large-diameter drilling and water infusion. (5)When using the synchronization technique of drilling and monitoring, drilling powder and stress change can be monitored for potential burst warning during drilling process. System establishment of control technique based on scientific classification still will be the direction of future research. [ABSTRACT FROM AUTHOR]

In view of the asymmetrical deformation failure in the mining roadway at a steeply inclined special thick coal seam, some field observations, mechanical modeling calculations and numerical simulation analysis were used to reveal the asymmetrical deformation failure mechanism after the excavation of the roadway in steeply inclined coal seams. The stress field after the excavation of the roadway and the distribution characteristics of the plastic zone were analyzed. A new support and reinforcement scheme for the retractable U-shaped steel and asymmetric prestressed anchor(cable)support was proposed. The study shows that:(1) the asymmetrical failure of the roadway is characterized by the subsidence, slippage, and internal expansion along the bedding of the hard rock strata along the side of the coal body; the subsidence of the top of the side of the hard rock is greater than that of the coal side and the central axis of the roadway inclines to the coal side. (2) The asymmetric deformation mechanism of the roadway is that, under the effect of nonuniform load, the angle and size of the counterforce of the shoulder angle support on both sides of the roadway arechanged. The reaction force of the hard rock lateral support is greater than that of the coal side. Also the inclination angle of the coal side is larger than the side of the hard rock. The side rock of the hard rock layer slides, sinks, and expands along the bedding under the action of small angle and large stress, and the side of the coal body is pushed out of the drum under the action of nearly vertical angle force. (3) The bending moment of the roadway from the side of the hard rock to the side of the coal body is increasing all the time. The shear force appears to increase first, then decrease and then increase, and the direction changes in the second increase. The position of the direction change is the offset position of the roadway axis inclining to the side of the coal body. The axial force appears as a parabola,decreasing first and then increasing. The optimum and reasonable section of the roadway under non-uniform load acts is the"asymmetric three-hinged arches". (4) The retractable U-shaped steel and asymmetric prestressed anchor(rope) support are proposed, focusing on reinforcing the lateral support of the roadway coal body and the top support on the side of the hard rock. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)