Applied Mechanics and Materials Vols. 580-583

Abstract: Security of secondary lining is of utmost importance to tunnel engineering quality as the main bearing structure and the last water-prevent line for rock types I, II, III. Tunnel lining with dislocation and cracks is one of the most serious defects to secondary lining. Based on the case of Goujiagou tunnel, the potential threat is listed. The pre-stressed regulation scheme is designed, and the parameters are determined. The loose surrounding rock pressure on lining is calculated by P's theory. Based on the results, the numerical simulation model is build by means of FES code ANSYS; and the internal pressure before and after the reinforcement is analyzed. According to the above-mentioned research results, this paper calculated the safety factor, and checked the structure strength. Research results indicate that the regulation design is feasible and the pre-stressed parameters are appropriate. The results will provide reference to design for dislocation and cracks of tunnel lining.

Abstract: Based on the measured data of the tunnel lighting, this paper is focusing on the arrangement of measured points in the experiment of tunnel lighting. Through the way of changing the location of measured area and the arrangement of measured points, comparing the simulation from the software DIALUX and the actual measurement in a repetitive region, the best position of measured area and the corresponding layout mode can be found. Analysis shows that, the larger the lamp distance is, the more similar the experiment and simulation results are. Before the experiment, the analysis of the light distribution curve is required, then, the simulation of software can help to find out the best position of lamp interval, measured area and layout mode, in order to ensure the authenticity of the results and to avoid too large or too small lighting evaluation, layout mode must include the maximum measured points and the minimum measured point.

Abstract: Subway station fire can easily cause many calamities that lead to a large amount of social and public problems, because the smoke spread moves in the same direction as the personnel evacuation. Therefore, life safety issues caused by the subway station fire and relevant investigation should be comprehensively taken into account in the fire safety design in order to minimize the fire accident loss. Here previously reported fire accidents in the subway station are reviewed in detail and some research on the life safety of the subway station fire are presented, which could be helpful for the accident prevention and provide guidance to future study on the safety design in the subway station fire.

Abstract: The fire accident is a substantial risk in the subway due to the complexity of the underground construction confined space, which can cause a large number of human fatalities. Therefore, some effort should be made to promote the public security in subway fire accidents. Among of them, the establishment of emergency evacuation plan is very important in fire safety design and should be paid enough attention because it can provide beneficial help to life safety. The evacuation strategy including the evacuation route and evacuation safety zone are detailedly discussed in this paper, which lays the foundation for future studies of safe evacuation in the subway fire accidents.

Abstract: Fire simulation software (FDS) was employed to simulate the fire smoke movement of urban traffic link tunnel (UTLT) under the semi-transverse ventilation. Numerical simulation and theoretical analysis were used to analyze the fire smoke movement in three fire scenarios. The analytical results show that: semi-transverse ventilation can effectively control the spread of fire smoke. When the exhaust air rate is certain, the exhaust port interval of 20 m and 50 m has little effect on function of smoke control. The research results provide references for the design of smoke control measures in UTLT.

Abstract: According to the analysis results about the distribution rules of tectonic regional stress in China mainland, the distribution rules of tectonic regional stress in Chuandian and the tectonic movement of Baihetan , the distribution rules of regional stress in Baihetan were preliminary analysed. Based on measured results of geostress and the statistical analysis of the measured results about the geostress of the shallow crustal magmatic in China mainland,the distribution rules of regional stress in underground powerhouse at the right bank of Baihetan hydropower station were studied. In general,the maximum and the minimum horizontal principal stresses and the vertical stresses increase linear with depth . In dam abutment.while in the underground powerhouse.Based on the measured results of geostress,the dispersed point charts of the ratio among the maximum horizontal stress ,the minimum horizontal stress and the vertical stress with depth in China were established, using the method from the statistical analysis of measured results about the shallow crustal geostress in China mainland and the corresponding regression analysis was studied.

Abstract: The construction method requires careful consideration in order to reduce impact of tunnel on the surface of the building in the city. It can have great significance in choosing appropriate blasting excavation method for the poor surrounding rock conditions and complicated ground constructions of shallow buried tunnel. This paper combines the Guanhui urban railway transport projects which the shallow buried tunnel through the dense residential areas, research on the influence of CD method and bench method with reserved core soil when use blasting excavation method on the surface buildings by finite element method. The suitability of two kinds of blasting excavation method in the urban shallow tunnels is analyzed and compared, eventually determine the CD method with blasting excavation is more suitable for the urban shallow tunnel construction, it provides reference and suggestion for future similar construction methods that tunnel construction under the city.

Abstract: Based on the dynamic monitoring project of one underpass in Dalian, this paper tries to validate the control effect of the ground settlement on the stability of tunnel surrounding rocks during construction of underground passage under urban arterial road by means of analyzing the vertical ground settlement curves, convergence curves of tunnel inner perimeter and vault displacement curves. With the numerical calculation tool of the software FLAC, it also analyzes the construction of XS-2 # cross-section which was in the south side of the whole construction section at different stages by adopting the plane-strain model. Therefore, we can get the influence curves of ground settlement under different construction stages with considering the release of stress. The simulation results are basically consistent with the measured data, which has a great significance for the subsequent design and construction of underground projects with similar geological conditions.

Abstract: Many excavation and backfill methods can be used to construct a deep foundation pit, but foundation pit construction will undoubtedly affects security of existing metro station. This research based on a transfer station of Chengdu Metro, three-dimensional numerical simulation method was used to analyze the deformation of metro station by changing construction methods of foundation pit. The results show that: (1) Both excavation and backfill methods of foundation pit have a significant effect on connection segments of metro station. (2) The main body of metro station is largely unaffected by foundation pit construction but it has been in the process of subsidence. (3) The more the construction steps of foundation pit are, the more slowly the displacement of metro station changes. The above results certainly contribute to research and develop new types of construction methods for complicated metro station.

Abstract: Combining with the practical engineering case, the paper summarizes the shallow mining method construction mechanism, construction methods and auxiliary technology. Aiming at the problems in the shield construction, the paper introduces the shield machine equipment’s latest comprehensive construction and technology, especially the shield technology dealing with the conglomerate stratum where the water and boulders is rich. It fills the domestic blank; Deep grouting and pipe roof reinforcement technology are aimed at the specific sources of risk; Whole cross-section of pallet trucks, electric vehicles, automatic metering and other new equipment have been widely applied to the construction site.