Applied Mechanics and Materials Vols. 170-173

Abstract: In urban environment, short-distance undercrossing of shield tunneling to an existent tunnel is an unloading process and can cause adverse effect on the existent tunnel. This kind of effect should be controlled. To analysis and control this effect, numerical simulation, field monitoring and optimization of construction parameter are used. To get reasonable calculation parameters for numerical models, field monitoring is conducted. The numerical simulation is utilized to study the process of short-distance undercrossing. The simulation result revealed that the deformation of the existent tunnel can be beyond the tolerable value unless some measure is adopted, but the deformation can be reduced significantly by improving the ground under the existent tunnel with cement deep mixing method. Construction measures are adopted, such as the strict controlling of synchronized grouting, secondary grouting, rotation speed of cutter head and driving speed. As a result, the deformation of the existent tunnel is controlled in the tolerable value.

Abstract: According to the Yuzhou Tunnel of Chongqing Airport Road in-situ expansion project under the IV and V class surrounding rock, this paper compares the construction mechanism among the three construction methods which can be used in the project. The results based on the construction mechanism analysis under different construction methods show that, it’s suitable to use bench method in the IV class surrounding rock and backfill method in the V class surrounding rock.

Abstract: Generally speaking, the pilot heading is aways used for geological exploration，speeding up the construction，improving the draining and Ventilation condition, promoting efficiency of residue transporting. When tunneling on high ground stress soft rock region，the pilot heading will play a more important role. Lan yu line Mu Zhai ling tunnel main passes through the region of carbonaceous slate. Due to the high ground stresses, the primary reinforcement system underwent large deformation, evenmore the lining is cracked. Through excaving the pilot heading, can relief the stress. Then enlarg the pilot heading to main tunnel, the deformation of primary support will be reduced, and the tunnel will be stable. Compare the "pilot and enlarging" excavation method with bench excavation method on surrounding rock deformation. As the result, the "pilot and enlarging" excavation method is effective for control of the deformation of the tunnel.

Abstract: In the tunnel excavation process, often encounter fault belt, soft interlayer and abnormal water-bearing body does not directly predict adverse geological structure, not timely prediction and control these geological disasters will affect the safety of production. In many prediction methods in geophysical technology with nondestructive, accurate, efficient, fast and be recognized, many shot-geophone reflected wave method in different geological conditions on the apparent impedance response, the migrated results can accurately distinguish the lithologic interface, in many projects has been confirmed. The paper introduces the multiple source-detector reflection wave observation system based on, combined with the specific project example, elaborated how the shot-receiver reflected wave method in tunnel face geological disaster prediction in rats.

Abstract: Analyze the role of tunnel lining structure calculation for the elastic resistance, and point out the influence of assuming elastic resistance of Budd-chiarieva method on calculation result and its shortages. Then put forward a new calculation method — Iterative method which can accurately determine elastic resistance distribution law of curved wall tunnel, and introduce basic idea, influencing factor of elastic resistance distribution law, practical method of Iterative method, and the method of improving iterative speed, and the process for calculating internal force of structure is given using Iterative method; contract the calculation results of internal force of structure by Iterative method and Budd-chiari eva method and point out the differences by practical calculation examples. Finally, the application scope of iterative method and necessity for further study are suggested.

Abstract: A Large-scale underground interchange tunnels will be applied in the Chongqing Two Rivers Tunnel project with six crossings and four interchanges adopting NATM. The paper analyzes and discusses the whole-process construction mechanical behavior of the underground interchange by the numerical analysis method, at the same time considering the similar project established, and then suggests some important design parameters about crossings and close overlap interchanges between NATM tunnels, such as proper space of crossings and interchanges. Through the analyses, the paper suggests the design and construction method and construction organization project, especially for the crossings and close overlap interchanges between the NATM tunnels. The paper discusses the key problems of an underground interchange tunnels, and first suggests a mode how to construct an underground interchange tunnels. So, it is important in theory and practical engineering.

Abstract: Abstract: I type horseshoe with flat–bottom evolved from standard I type horseshoe cross-section. It is composed of a flat-bottom and three arc sections. It is commonly applied in the field of hydroelectric engineering. The normal water depth computation equation for I type horseshoe cross-section with flat–bottom tunnel is a transcendental equation and no analytic solution. In this paper, based on the mathematics transformation for the basis equation and the relationship analysis between the dimensionless normal water depth and the relative parameters, a direct solution is established for the calculation of normal water depth for I type horseshoe cross-section with flat–bottom tunnel according to the fitting principle. This method overcomes the shortage of other iterative trial calculating methods, such as complex calculation step, depend on the special chart and curve, and existed serious error. The formula is simply and the maximum error is less than 0.3% under the general engineering design range (ratio of normal water depth and arch radius is between 0 to 1.4471). it can be used on the engineering designing practice and the edit of the handbook of hydraulic structure design.

Abstract: According to the characteristics of tunnel anchor now，the analysis of test means of the tunnel at present stage，put forward in different conditions, the most appropriate anchor test method and the verification method corresponding，to make up for the defect of the single detection method, make tunnel test results more scientific. Introduction

Abstract: In recent several years, coal mine tragedies had happened frequently in Chinese, a minimum life sustaining atmosphere would need to be developed to design any sort of refuge chamber for entrapped miners to await mine rescue teams. Parameters such as oxygen consumption rate, carbon dioxide exhalation rate, and maximum allowable temperatures inside such a chamber for human survival had to be defined.

Abstract: The paper takes the deep exploitation of Sanshandao gold mine as the research subject , the methods of distribution of rock structure and lithology examination, in-situ rock stress measurement, physical and mechanical tests of rock, and fuzzy mathematic prediction are used to study rockburst tendency in deep development and exploitation of the mine, which fill the gaps for the past using only one qualitative indexes of rock to judge the possibility of rock bust, and make the evaluation results more close to the objective reality.