Applied Mechanics and Materials Vols. 580-583

Abstract: When crossing difficult terrain or extreme regional geological conditions encountered, there are difficulties in laying road routes, the spacing between two adjacent tunnels is limited. Neighborhood tunnel is a form of tunnel structure between separate and arch ones, less affected by the topography. It is more conveniently and easier to control the cost. Surrounding rock deformation mechanism with construction of three-step method is more complex, and therefore a reasonable means of construction technology and support is essential. Taking a certain neighborhood tunnel highway engineering background, aimed to provide guidance for follow-up monitoring and support, we use numerical simulation software FLAC^3D on three-step method excavation construction. Rational creep analysis of geotechnical model and calculation parameters is selected. It helps to calculation and analysis the mechanical response of tunnel surrounding rock characteristics and clarify the tendency of displacement and stress fields.

Abstract: Taking the first fully mechanized caving face in Xiagou coal mine as research background, through the pressure observation on the scene field of fully mechanized caving face with rock burst danger, this essay reveals the pressure appearance law of coal seams rock burst danger and concludes that the field roof structure of fully roof mining is more conducive to the release of coal rock stress compared to layered mining structure and this method plays a mitigation role on moving pressure shock of coal rock. The fully mechanized caving faces can be explored fast under safety conditions. The research results are of great theoretical and practical significance to the mining production with similar geological conditions.

Abstract: In order to tunnel safely, efficiently and economically, we carried out the study on geostatic stress characters and optimizing bolting support parameters in 2# coalbed of Zijin Colliery. Based on the surveys of geological conditions, original rock stress, broken rock zone measurement and analysis of roadway deformation, characters and mechanism of roadway failure is figured out. According to existent problems, normal support theories were used and a variety of numerical computations were carried out by FLAC^3D.New support methods of bolt installed vertically in tilted roof and strengthen support of sidewalls and corners of roadway were figured out. Monitoring of convergence meters and roof separation were followed to know effects of new design timely. The research was carried out for 600 meters The monitoring results proved that the optimized support design was viable and the new bolting parameters were reasonable.

Abstract: Based on the railway tunnel engineering, the research on comprehensive technological for the monitoring of tunnel construction is performed. It is shown that the deformation of wall rock would mainly suffer the comprehensive influence of multiple factors like type of the wall rock, construction method and supporting measures, size of the excavated section, etc. through the monitoring of the crown settlement, clearance convergence and ground settlement. The wall rock will be stable within 20d and 40d after the tunnel excavation. And the secondary tunnel lining could be constructed. Numerical simulation method was also adopted to analyze the deformation and stress of the wall rock. It is presented that the construction interval shall not be too long for the stability of wall rock. Therefore, the numerical analysis method and site monitoring method could be used together to achieve more comprehensive and reliable monitoring of tunnel construction.

Abstract: Support of soft rock is a big challenge in all mines at home and abroad. Soft rock is of different kinds of rheological property for geological conditions, mine ground pressure and so on. It brings about really difficult problem to roadway support. In order to ensure safety application and prolong usage, shaft station need to be reinforced. Sight instrument was used to analyze broken conditions. The results show that the broken depth in roof rock is 5~6 m, and greater than 4 m in sidewalls. According to failure characters and sight results, we determine that rock of shaft station belongs to high geo-stress and jointed soft rock. On this basis, technology of grouting reinforcement combined with cable anchor support is carried out. Monitoring results of surface convergence and cable force show that bearing capacity of surrounding rock increases obviously, roadway contraction and floor heave are well controlled.

Abstract: Stability classification of roadway surrounding rock is of great significance as the prerequisite of safe production in roadway engineering. Based on a great number of issues analysis, the research status of roadway surrounding rock stability classification has been dissected from aspects of classification indexes and methods. At the end, it has put forward that choosing scientific and reasonable indexes, applying combined technology with more than three methods, using new technology and new methods are the three development trends of roadway surrounding rock stability classification research.

Abstract: In this article, we focused on changes of mechanical properties in lining of tunnel caused by loess cavity. We established a corresponding model and carried out numerical analysis by using finite element analysis software ADINA, considered the effect of different locations, different size of the cavity and depth of the tunnel. The results showed that change of the mechanical properties has the largest effect on the lining at the arch foot nearby the loess cavity, and it grows with the growth of the cavity‘s size and depth of the tunnel.

Abstract: Since the excavation of roadway in Shuguang mine No.2 mining area, shotcrete layer has fallen off and the surrounding rock deformation was serious. For studying big deformation of roadway in Shuguang mine No.2 mining area, the paper analyzed fractured surrounding rock physical and mechanical characteristics of No.2 mining area. The results show that the uniaxial compressive strength, uniaxial tensile strength, cohesion, internal friction angle of fractured surrounding rock were very low. And the whole physical and mechanical characteristics were poor. It is the basic reason of big deformation of roadway surrounding rock physical and the important basis of late supporting of roadway.

Abstract: The paper aims to solve the serious and regular crack problems in underground garage. ANSYS finite element software is applied to set up the overall finite element model on floor-foundation and foundation coupling beam-foundation soil in underground garage. Combined with engineering field detection, factors influencing underground garage floor like underground water level, soil expansion caused by water content change in expansive soil, soil poisson ratio, foundation settlement are taken into consideration to find out the causes of cracks. The study is expected to provide reference for similar cases in other projects.

Abstract: Lining cracks of highway tunnel has a very important effect on the healthy operation of the tunnel. Establishing the model for concrete fracture mechanics evaluation, we could identify the tunnel lining cracking situation. By using Linear elastic fracture mechanics method we could calculate the stress field of crack in the lining. Separately by different depth we have calculated crack stress intensity factor. We get that growing rates of variation of stress intensity factor as the crack depths increase. So lining tunnel health operations severely cracked.