Advanced Materials Research Vols. 1065-1069

Abstract: Through site test, the paper conducts site test to vertical vibration accelerations when a train passes through steel rails and tunnel walls at a steel spring floating slab track section and a general track section in the tunnel of Yizhuang Line of Beijing Metro. The paper also conducts comparative analysis of the accelerations in time domain and frequency domain. It is shown in results that the vibration acceleration level of the steel spring floating slab track in time domain is reduced by 22 dB in tunnel walls in comparison with the general track; in the frequency domain, the vibration effect is gradually increased with frequency increase and reaches the optimal effect in medium-high frequency. The maximum vibration attenuation quantity of frequency division reaches up to 40 dB; and the maximum Z weighted vibration acceleration level is reduced by 22 dB.

Abstract: Relying on the construction of a deep underground reservoir, vibration effects of ground were studied from two aspects: the peak value of vibration velocity and the basic frequency of blasting seismic waves, and were compared with the blasting vibration effect on the flat terrain surface. Research shows that blasting seismic wave’ impact on the surrounding building is relatively small because of its high frequency for the blasting excavation of underground reservoir. The frequency distribution in vertical and horizontal direction with scaled distance is roughly the same. And the peak value of vibration velocity in vertical direction is greater than that in horizontal direction, so blasting vibration effect in vertical direction is bigger than that in horizontal direction.

Abstract: Rainfall is the main factor that affecting water inflow of the tunnel in the bare karst areas of Southwest China. Affected by the development of karst aquifer system, rainfall infiltration recharge for groundwater has obvious lag time. The water inflow of tunnel is not only concerned with the intraday rainfall, but also related with the antecedent rainfall. In this paper, taking the Yesanguan Tunnel and Maluqing Tunnel as examples, the correlation between rainfall in different periods and water inflow was analyzed, and then the regression equation was established to forecast water inflow. The results show the predicted result is affect by the precision of the observation data, the development degree of karst, the infiltration and the discharge conditions of rainfall. Meanwhile, the correlation analysis is not suitable for some cases, such as the area which has greater changes of groundwater recharge and discharge under different rainfall conditions.

Abstract: Our country is facing special circumstances as it is now a divided nation. People are allowed to evacuate to adjacent public facilities within residential areas in the case of emergency. In particular, the main facilities of subway stations are facilities designed for the convenience of passengers so they have emergency shelter conditions. However, the legal system for the use of subway stations as temporary shelters during disasters has yet to be instituted. As a result, the consistent application of the system is difficult. The lack of correlation between the relevant laws also makes it difficult to prepare shelters quickly during an emergency. The role of relevant departments and the scope of disaster recovery may vary depending on the relevant laws. In this study, the improvement criteria were divided into four based on findings regarding the problems identified in existing standards. In conclusion, this study focuses on suggesting improvement schemes with respect to the coverage of victims, area criteria, equipment criteria, and disaster relief goods.

Abstract: Bearing capacity tests of three reinforced concrete lining segments were carried out. The effect of the loading method and ultimate bearing capacity of the reinforced concrete lining segments and the maximum displacement and reinforcement ratio on the failure mechanism was analyzed based on the simulation results. The simulation results show that the yield load and ultimate load of the lining segments can be effectively increased because of the axial force effect. the loading method on the full surface was proposed. The the ultimate load and yielding load increase as the reinforcement ratio increase is radial distribution in the state.

Abstract: From 1950s 13 NEE ground fissures have been found in the suburb and downtown area of Xi’an city. Ground fissures bring harm to the Xi'an municipal construction, especially to the subway construction. By dynamic characteristics of Xi’an ground fissures, factors influencing differential settlement are analyzed and a conclusion is drawn that exploitation of ground water and the differential clay thickness on both sides of ground fissures is the governing factor. The amount of differential settlement in the following 50 years is predicted by ground-water Model and Verhulst Model. Good agreement is shown between these results. It leads us to suggest that the differential settlement will cut off the subway tunnel in the future and actions must be taken in the design phase of subway tunnel.

Abstract: Based on the peck formula, this paper has analyzed measured data of ground surface subsidence, and get the regression curve of ground surface subsidence. Expression for degree of reliability of the maximum ground surface settlement is derived analytically by using central-point method. On the basis of a certain section of tunnel of Guangzhou subway constructed by mining excavation method, linear regression method can be effectively fitting the ground surface deformation data due to tunnel excavation. The central-point method provides a new way for reliability analysis of the ground surface settlement of shield construction.

Abstract: For the present open cut method is still the main method of the construction of metro stations. Foundation pit support structure and lining structure are composed of three basic side wall structure systems (single wall, compound wall and composite wall). In the calculation of internal force of structure, complex interactions between foundation pit support structures including bored pile and diaphragm wall, and the side wall of main structures are investigated. One form is that the foundation pit support structure and side wall can only deliver pressure and separate partly; another is that they deform together by construction measures. In this paper, the effects on the internal force of main structure influenced by foundation pit support structure are quantitative studied, and the reference resources for optimization design are provided.

Abstract: For a nuclear power intake tunnel project, large-scale three-dimensional finite difference model is established by Flac3D to simulate the seismic response regularity of the entrance section of tunnel under the action of seismic waves schedule with the nonlinear dynamic analysis method. Through the input of the site seismic wave, the structure response characteristics of the tunnel entrance and slope are explored and duration curve of tunnel hole lining force under seismic waves action and tunnel lining figure can be obtained. The analysis results show that the anti-seismic weak parts of the tunnel entrance is at the location of tunnel spandrel and the sidewall. The analysis method and conclusions can be for reference in the seismic design of similar nuclear power intake tunnel project.

Abstract: In the process of production of Zhengli mine 14^-1103 working face, found that though the existing supporting system can satisfy the requirement of support, there will be a bulge in a few places, anchor invalidation etc. In order to guarantee safe production and high efficiency production requirements, it is necessary to optimize the working face support. In this paper, by the method of numerical simulation, compared the original support and optimized system, test the optimized supporting effect. It’s proved that lengthen the top bolt is an important measure for optimizing the support system.