Advanced Materials Research Vols. 243-249

Abstract: This article used Geotechnical Engineering General Software FLAC^3D to simulate the tunnel CRD method under 1.5m, 2.0m, 2.5 m, 3.0 m footage separately and analysis the influence to the tunnel surrounding rock stability in the different footage construction. This paper selected a real tunnel project as the research object and analysis comparatively the rule and characteristic of various methods of tunnel surrounding rock displacement, stress distribution and the plastic zone size through simulated computing the different footage construction. The results show that,Ⅰ.Considered from the surrounding rock stress control that the 1.5m footage adjacent formation stress adjustment effect is best, next is 2.0m, 2.5 m, 3.0 m;Ⅱ.Considered from the plastic zone size that the 1.5m footage control effect is best, next is in turn 2.0m, 2.5 m, 3.0 m;ⅢConsidered from the surrounding rock displacement control that 1.5 meter footage adjacent formation control effect is best, but 2.0 meter, 2.5 meters and 3.0 meter phase differences are not big.

Abstract: Drift-PBA method has been widely used in the construction of metro station. Yet the discussion about the excavation sequence of headings was still a controversy. In this paper, three-dimensional numerical simulation of a metro station construction by drift-PBA was conducted by MIDAS/GTS. The heading construction sequence was studied in the environmental impacts due to the construction, and some suggestions were provided for the site. The calculation results indicated that excavating the upper headings previously could effectively control the shapes of settlement troughs and the deformations of pipelines, and diminish the disturbance to the stratum.

Abstract: The museum is adjacent to a subway tunnel, cultural relics may be damaged by the vibration induced by subway transit, so the vibration influence of museum must be strictly controlled. By building the three-dimensional finite element model which contains floating slab and isolation ditch, the calculation and analysis for each layer vibration acceleration value of the museum caused by the subway will be done. The results of the study indicate that vibration acceleration value were not more than vibration control limits, vibration reduction and isolation reach the predetermined purpose.

Abstract: The paper analyzes the fire-resistant performance of big tunnel structure by setting up the analyzing model of tunnel-surrounding, choosing the characteristics of concrete, according to the lengthways and crosswise temperature distribution in specific scene of fire, analyzing the temperature and stress field of the tunnel structure, and knowing the basic rules and the damage of the lining and inner equipment of the tunnel by high temperature which is set on the Shanghai Yangtze tunnel. Tunnel lining is made up of reinforced concrete duct pieces. Concrete is a kind of non-homogeneous composite material, which would experience complex changing both physically and chemically by the high temperature, and the changing will surely lead to the descent of the carrying capability of the integral mechanical properties. The thesis studies the basic rules of the tunnel on fire and the damage of the tunnel lining structure and the inner equipments by the high temperature, which is set in the Yangtze River Tunnel in Shanghai, thus contributes to analyze the demand of the joint action of the disaster prevention, the ventilation system and other equipment and to reduce the fire loss.

Abstract: In order to study noise emitted by metro train, the experiment is carried out in the test line of Shenzhen Metro Line 1. It can be concluded that the noise outside the metro train is mainly middle and low frequency; the higher the train speed is, the larger the noise is; In static condition, the higher the measuring point is, the larger the noise is while in constant speed condition the higher the measuring point is, the smaller the noise is.

Abstract: Shield tunneling construction inevitably makes impacts on underground utilities. This paper takes some Metro engineering for background, study the underground utilities settlement rules induced by shield tunneling construction. As for shallow-buried and high ground water table tunnel, the coupling of hydrological and stress field must be paid attention. By seepage continuity equation and hydrodynamic equations, study changing situation of the deformation and stress by contrast the effect of seepage. And, contrast the measured value and simulation value to verify the rationality of using fluid-solid coupling method to forecast the ground settlement during tunnel construction.

Abstract: To get optimum blasting parameter bringing out the best blasting outcome is very helpful to increase the speed and efficiency in tunnel-building. For this reason, the effect of blasting parameters on blasting outcome is analyzed based on that the rocks are complex and changeful through which the tunnel is driven and that there is a gap between blasting theory and blasting practice. The method helpful to get the optimum blasting parameters is present in which the blasting outcome is measured, recorded and analyzed, and the blasting parameters are adjusted aiming at the specific tunnel according to the blasting theory and the blasting technician’s experience. The presented method is important and significant for improving the tunnel-building technique by blasting, realizing the high speed and efficiency of tunnel-building by blasting.

Abstract: This paper describes the moving scaled-model test of express container car passing through a tunnel on moving model rig where its scale is 1/17.6 and the length of the tunnel is 888.8m and the section area of the tunnel is 80 square meter and the interval of two truck is 4.4m in full-scaled model. The tests include that the container car passing though a tunnel with its speed are 120, 140,160 and 176km/h separately and its lowest Renolds number. The results show that the figure of the pressure wave on the car body is almost the same when train is in tunnel with different speed and that the amplitude of the pressure wave is proportion to the square of the train speed. The pressure on the car is always negative when train is in tunnel while the pressure on the wall of tunnel alternate between positive and negative. The coefficient of pressure wave on the car body is -0.7 and the peak values of pressure coefficient of point on tunnel are 0.6 and -0.7. The amplitude of the pressure wave on the car decreases according to logarithmic law nearly. The amplitude of the micro pressure wave is proportion to the cubic of the car speed.

Abstract: Using wavelet transform, signal’s frequency properties of vibration induced by underground are analyzed A MATLAB program is developed in order to decompose and reconstruct acceleration signals. The law that acceleration signals change in time-spectral domain is got. Then the relations of vibration signal’s maximum acceleration, energy, frequency and spectral are discussed. In contrast to conventional Fourier Transform， wavelet analysis can provide the evolution of spectral features of a signal as this evolves in time. It is ideal for random and non-stationary signal analysis.

Abstract: With the development and utilization of underground space and the construction of large quantities of shield tunnels, the phenomenon that shield tunnel go through the existing buildings at close quarters is in the rise. The stiffness mismatch between shield tunnels and existing buildings has a significant impact on the deformation and stress of the connection part. In order to explore the affection on the shield tunnel from the existing buildings while the shield tunnel crosses the later, taken the shield tunnel crossing Wuchang ultra-deep ventilation shaft in Wuhan subway as an example, the influence to the shield tunnel by the existing building is studied. In the sphere of influence, the closer to the ventilation shaft enclosure structures, the more notable the uneven deformation of the tunnel segment structure would be; the closer to the rigid structure, the smaller the transverse bending moment would be; the nearer to the rigid structure, the greater the horizontal axial force, vertical axial force and vertical bending moment would be. The impact on deformation and load-carrying capacity from ventilation shaft enclosure structure on shield tunnel segment weakens sharply by the increasing of their distance.