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Copyright of Transportation Science & Technolgy is the property of Transportation Science & Technology 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 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.)

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.)

UDEC is used to analyze the surface subsidence characteristics under different steps of fully mechanized and layered mining face. The research results show that the trend of surface subsidence in the lower layer mining face and the fully mechanized mining face is basically the same, and the extreme value is in the middle back position of the goaf, but the maximum subsidence value of the lower layer face increases by about 30.9%. The sinking coefficient is reduced by about 11.5%; the extreme value of sinking speed of fully mechanized mining face increases with the increase of step of working face, and shifts to the direction of push mining, while the extreme value of sinking speed of lower layered working face relatively decreases; the horizontal movement of the stratum mining face is more violent and fluctuating than that of the fully mechanized mining face. The positive and negative values of the horizontal movement increase by approximately 45.2% and 63.6%, respectively. The influence range of the fully mechanized mining face is greater than that of the layered mining face. Compared with the fully mechanized mining face, the leading influence angle of layered mining under the layer mining face is reduced by about 4.38%, and the boundary angle is reduced by about 1.43%. The conclusion is to provide guidance for rational determination of the mining method.

Taking the anomaly of dredging and draining water in the Jining No. 2 coalmine as an example,this study predicts the development position of bed separation in the discriminant formula based on the composed rock beam theory, simulates the dynamic development process and distribution regularity of bed separation using discrete element software UDEC,and probe the position and spread of bed separation through 3D seismic. The result shows that the maximum bed separation developed in the larger gap between mudstone and middle-fine sandstone after the working face completed,the distance between the gap and coal seam is 60 m approximately. Based on the elastic thin plate theory, the study predicts the volume of bed separation by calculating the difference of deflection between upper and down rock plate. The predictive value can be used as the maximum total volume of bed separation developed in seam roof. [ABSTRACT FROM AUTHOR]

In order to study the developing law of sliding ground fissures caused by underground mining in the western loess hilly mining area of China, the definition and basic features of sliding ground fissures were given firstly in this paper. The dynamic developing model, gully gradient model, and gully position model were established using the UDEC numerical simulation software. Then, the dynamic developing law of sliding ground fissures was analyzed, the relationship between sliding ground fissures and gully was studied, and the reliability of models was validated through the engineering example at the 52304 working face in Daliuta Coal Mine, China. The results show that:① The development of sliding ground fissures could be divided into four periods, such as the accumulation period, the formation period, the dynamic developing period, and the stabilization period.② The relationship between sliding fissure angle and gully gradient was the quadratic polynomial equation, and the relationship between sliding fissure angle and gully position was the linear equation.③ The engineering example showed that the maximum relative error between the calculated values and the measured values of sliding ground fusser angle is 3.4%, which proves the prediction on the position of sliding ground fissure using this model is feasible. [ABSTRACT FROM AUTHOR]