| Rockbolt shotcrete support as a traditional way of supporting, was used widely in roadways and other underground fields, had achieved good results and accumulated rich experience. With the shallow coal resources are depleted, coal mine roadways had developed to the deep direction, the existing theory of rockbolt shotcrete support were behind the development of the status quo, it is difficult to adapt to specific practical situation, existing theories can not meet the requirements of practical application,especially those roadway support in high stress and complex geology. Therefore, it is necessary to adopt the numerical simulation methods to analyze the rockbolt shotcrete support under certain circumstances on the existing basis of research results,as to apply the technology of rockbolt shotcrete support more scientificly, more effectively and more reliablely.This paper analyze the character of deformation and the mechanism of the wall rock in high stress roadway,the type of rockbolt shotcrete support, mechanism and principles and the principle of total quality control of the rockbolt shotcrete support technology were introduced based on large number of documents.Compared with the analytical method and similar simulation which based on a number of assumptions, numerical simulation shows more advantages and has strong adaptability, it must recur to numerical simulationin in many complex conditions. This paper take the specific project for example, the rock physical and mechanical parameters had made based on the site investigation, sampling and testing, FLAC3D software was used to establish numerical simulation model of this roadway, the actual high stress situation and the complex geology distribution were considered when the numerical model was established. In order to simulate the actual situation better, a50×50x16.8m three-dimensional numerical simulation model was established, it was devided to8Excavation sub-departmens, each excavation sub-departmen was2.1m, the Mohr-Coulomb criterion was adopted to simulate the distribution situation and laws of the displacement of the wall rock in this roadway,plastic zone and stress of the full section excavation and support,and the top heading and bench excavation and support in complex deformation were simulated more really.Meanwhile, this paper also simulated the vertical displacement of the roadway roof and floor, horizontal displacement of the two sides,and the distribution of plastic zone when the horizontal stress coefficient K=0.25, K=0.5, K=0.75, K=1.00, and K=1.25.When the tunnel axis and the direction of horizontal stress have different angles, the wall rock shows different characteristics of the stress distribution and laws of deformation.The numerical simulation method was adopted in this paper and a three-dimensional numerical simulation model of120×50×16.8m was established to analyze the deformation, stress of wall rock and the distributionin of plastic zone when the angle of the roadway axis and the direction of horizontal stress was between0°and75°.It provided a guidance for the reasonable layout of the roadway under high stress conditions.The range and laws of wall rock deformation and stress were also discussed when rockbolt shotcrete support of whole section excavation was in a certain distance from the cutting face,meanwhile, the situation of wall rock deformation was also discussed when the prestressed rockbolt shotcrete support was used.In order to evaluate the stability of the wall rock and the reasonableness of the supporting structure for the experimental roadway,the displacement of top-floor and two sides were be measured in the process of the roadway construction. Numerical results and the actual measured results are basical consistent, it can be considered that: the results of this numerical simulation analysis is feasible, and it will play a role of conference and guide for design and construction of the rockbolt shotcrete support of the follow-up roadway.Finally, different pitch, different bolt length,different bolt diameters, different bolt spray angle and different shotcrete thickness were optimized from the aspects of the displacement of the roadway roof-floor and two sides,the maximum principal stress and the minimum principal stress.Therefore, there was a comprehensive understanding of the rockbolt shotcrete support technology under the situations of particular formation and wall rock,as to guide the design and construction better to improve the reliability, rationality and economy Figure108; table9; reference52... |
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