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Xiang Z.,Central South University | Yuan R.,China Railway First Group Co.
Advanced Materials Research | Year: 2012

studies were carried out to determine the principles of mechanical equipment coordination for large cross-section tunnel construction in combination with the tunnel construction practices within the sections under the charge of China Railway First Group Co., Ltd. On Wuhan-Guangzhou PDL and with a view to optimize the allocation of resources and improve the efficiency of large cross-section tunnel construction. Directed to different procedures such as excavation, support, waterproofing, drainage and lining, the mechanical equipment coordination and operation mode of large cross-section tunnels on the passenger dedicated line were established and the mechanized working faces were formed, which provide experience and reference for the large cross-section tunnel construction of passenger dedicated lines.

Xiang Z.,Central South University | Yuan R.,China Railway First Group Co.
Applied Mechanics and Materials | Year: 2012

The construction geological condition is complex in the transition section from the inclined shaft to the main hole. There are two kinds of construction schemes. After the comparison of the advantages and disadvantages of the two different construction schemes, it has selected the construction scheme of the rectangular pilot tunnel vertical to the main hole. This paper solve the construction problem of the transition section from the inclined shaft to the main hole of large cross section tunnel of passenger dedicated line under complicated geological conditions. According to the previous research results, the method can be used to large-cross section tunnel. The scaffold design and auxiliary construction measures is detailed. Compared with the expected duration, it completed the transition construction ahead of time with the speed superior to the ones of other similar works, and forming a safe and efficient construction situation. © (2012) Trans Tech Publications, Switzerland.

Zhang Y.,China Railway First Group Co.
Modern Tunnelling Technology | Year: 2013

It is a key point for the security of deep foundation pit enclosure structure in the design of deep foundation pit support which guarantees the normal construction of foundation pit and prevents from soil mass movement inside and outside the pit in order to keep the normality of buildings, roads and pipelines nearby. Special attention was given to the soil mixing wall featuring good applicability, low construction cost and short construction period. Based on the construction practice, some discussions of the key techniques in the design and construction were made regarding the application of soil mixing wall with a large diameter to deep foundation pit in soft soil.

Cui K.,Central South University | Cui K.,China Railway First Group Co. | Zhang M.,Central South University | Wang X.,Central South University
Zhongguo Tiedao Kexue/China Railway Science | Year: 2010

Based on the slip surface model of foundation damage used in the Meyerhof solution for the ultimate bearing capacity of deep foundation, the ultimate bearing capacity at the tip of a pile that is embedded in rock is deduced by applying the generalized nonlinear unified strength criterion and slip line principle for resolving the differential equation systems which govern the stress field. Then, the variation laws of end bearing capacity with sliding surface angle and embedment ratio are studied. The impacts of intermediate principal stress and overload factor are discussed in the analytical solution. Results show that the end bearing capacity decreases nonlinearly with the embedment ratio, but increases with respect to the intermediate stress parameter. And the bearing capacity factor increases with the overload coefficient hm when the embedment ratio n is smaller, but decreases while the embedment ratio is greater. The end bearing capacity defined by current pile design code is conservative according to the calculation results.

Lai J.,Changan University | Qiu J.,Changan University | Pan Y.,Urban Railway Company | Cao X.,China Railway First Group Co. | And 3 more authors.
Modern Tunnelling Technology | Year: 2015

Segment defects like cracking, damage and dislocation have extremely adverse effects on shield tunnels. Using the water inflow event of a shield tunnel on the Xi'an metro as an example, this paper analyzes the situations and relevant causes of segment defects by utilizing field surveys, GPR detection, ultrasonic crack detection, displacement measurement, etc. The results show that: 1) the damages occurred on the segment at an early stage due to the cavities formed around the segment ring and the irregularly distributed loads upon it; 2) the displacements occurred on the segment because of additional asymmetric loading caused by grouting pressure, the cumulative lateral displacement of which was 3.4 cm with the upward movement reaching 5.5 cm at the end of grouting; and 3) the maximum depth of segment crack was 134.9 mm and its maximum width was 1.0 mm. ©, 2015, Editorial Office of "Modern Tunnelling Technology". All right reserved.

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