Applied Mechanics and Materials Vols. 501-504

Abstract: The cracking and deformation analysis of concrete tunnel segment in the jacking process is made by ANSYS. First, we analyzed the effect of such measures as placing a hydraulic jack between the section and rail beam sliding plane described in the four sliding rails scheme upon the cracking and deformation of segment concrete, then the influence of change in spacing of two sliding rails at the same side on the cracking and deformation of segment concrete stated in the six sliding rails scheme. Meanwhile, we made a comparison between the two layout schemes, thereby providing a basis and reference for the layout scheme of sliding rails in the practice.

Abstract: Analyzing and summing up the engineering geological and hydrogeological features of Nanning No.1 6 Subway, types strata combination model are put forward, which combing the first exploration data. Then the URT Line 1 is divided into 5 kinds engineering geology partition. At the same time, all engineering geology partitions engineering characteristic and engineering problem possibly appears are analyzed, drawing a conclusion that these first three types partitions shield tunnel may have more problem in the process of construction.

Abstract: It has been a technical problem of upward movement for shield tunnel segment during construction. a segment floating calculation formula was deduced through using basic theory of mechanics and mathematics, detailed tension analysis of segment. The computation example of engineering showed that the result obtained by the proposed calculation formula was well consistent with the monitoring result and could be used to analyze the upward movement of shield tunnel. Moreover, the conclusion provided some reference to similar projects.

Abstract: Calculated the long-term settlement of metro line 1 at Hexi region in Nanjing which constructed by opencut method under static load. It also considered the effect of composite foundation, then made comparison between calculation and measured data. The results show that: The calculation results are basically consistent with the measured values. The settlements of the whole line are uneven obviously. Tunnel settlements are related with the thickness of overburden soil and the property of underlying layer.

Abstract: In order to study the influence on the different parts of the cavern by joints, the three-dimensional model is built by Patran and then calculated with FLAC3D after meshing. Seven working conditions about different inclination of joints (0°15°30°45°60°75°90°) are considered in the calculation. The results show that low dip joints in vault and steep joints in the sidewall are more dangerous. Therefore, some measures should be used when encountered this situation in this project.

Abstract: With the rapid development of metro engineering construction in China, the impact of shield tunneling on adjacent existing building has been paid more and more attention in recent years. Taken the Jiulongshan-Dawanglu running tunnel of Beijing Subway No.14 built by shield method as engineering background, a three-dimensional numerical model based on the soil-structure interaction theory is established by using the finite element software ANSYS to simulate the shield tunneling beneath the adjacent existing running tunnel of Beijing Subway No.1. The displacement of the adjacent existing running tunnel is predicted. During the shield tunneling, the vertical deformation of the adjacent existing running tunnel can reach up 2.8 mm, and the horizontal deformation value is about 0.5 mm, which can satisfy the project need and the requirements of relevant standard. The numerical results can be regarded as a valuable reference for the construction.

Abstract: With the speedy development of urban mass transit in China, more and more building environment problems are coming forth in many cities. How to choose available construction method to fast, safely and economically build subway engineering is worthy to be urgently studied. A new-type subway station construction method called top-down boring with cast-in-situ arch is presented through a large number of design calculations, research and analysis, on the basis of conscientiously analyzing traditional tunneling methods and engineering practice. Some advantages of this new method are briefly introduced, compared with the shallow mining methods for underground engineering construction, as well as its application in subway engineering. According to further study, this new construction method will be widely used in underground engineering projects. At the same time, the relative theory of this new method will be validated and promoted.

Abstract: In consideration of the geology and hydrogeology of the strata in Chengdu city, and in view of the general depth of subway station, its main structure and retaining enclosure for foundation pit constructed with open cut method is generalized in this paper. In order to expound the design of subway station structure with open cut method, a typical design of subway station in Chengdu subway line 7 is illustrated in the paper. The design of open cut subway station structure and its enclosure in Chengdu is still summarized and can be used to guide the structural design of subway stations under similar conditions with open cut method (OCM).

Abstract: On the basis of surrounding environment, including ground geological and hydrogeological condition of a connection line between line 1 and line 3 in Chengdu subway, open cut method is used to build the connection line. The whole line is divided into three sections, shotcrete and bolt support is adopted to maintain the stability of foundation pit by slope excavation, well rotary bored piles are used to support other foundation pit of the connection line. Meanwhile, the designed parameters of dewatering well points for the open cut tunnel are discussed and the anti-buoyancy ability of open cut tunnel is also analyzed in the paper. The purpose of this paper is to lead the design of open cut tunnels in Chengdu cities, including such similar subway tunnels in other cities in the world.

Abstract: Stability analysis of surrounding rock mass of Hongping underground caverns are studied by means of numerical simulation using Fast Lagrangian explicit finite difference method. The process of excavation and support are simulated. The pattern of deformation, stress state, and the distribution of plastic areas are analyzed. Finally, the whole stability of surrounding rock mass of underground caverns was evaluated.