Search

In the internal support system of foundation pit engineering, concrete support has been widely used in foundation pit engineering due to its advantages of high bearing capacity, unrestricted layout, cast-in-place end nodes and good integrity. However, the disadvantages of concrete support in design and construction are also very obvious, with problems such as large design section, long construction time, heavy pollution, high cost and serious waste. Therefore, in view of the advantages and disadvantages of concrete support in foundation pit engineering and combined with the characteristics of deep foundation pit engineering of metro open cut station, the prefabricated composite concrete filled steel tube internal support is designed in this paper. From the perspective of improving the stiffness and strength of end joints and achieving fixed connection at the end, a fixed end composed of long bolts and mold bag concrete is proposed, which is suitable for the prefabricated composite steel tube concrete internal support of metro foundation pit. The design scheme, structural characteristics and working principle of the fixed end are explained and compared with the cast-in-place concrete support node, which shows that the fixed end plays the role of fixed support in the support system, which is composed of special components such as embedded steel plate, hollow flange, bag concrete and long bolt. In order to establish the theoretical basis for the design and check of the fixed end, the analytical method of the compression and bending load-bearing capacity of the fixed end is obtained by analyzing the mechanical mechanism, failure mode and evolution law of the fixed end. In order to verify the feasibility of the theoretical analysis method of the bearing capacity of the fixed end, the theoretical and numerical results are verified and analyzed by numerical simulation, and the main factors affecting the bearing capacity of the fixed end are parameterized. [ABSTRACT FROM AUTHOR]

The segment assembly problem of shield tunnel in the transition curve part is always a difficult problem in the construction process because of the complex shape of the transition curve and the changeable points of segment assembly. Based on the requirement of staggered assembling and wedge segment characteristics, this paper puts forward a method within the plane to complete every piece of assembling construction by calculating and judging the condition of error control with comprehensive comparison of standard ring and wedge ring combination, and fit out design and varification methods, which meets the specification and control index and guarantees ing uniform linear axis in segment assembling. According to the actual engineering needs, the maximum allowable deviation control method and the segment assembly optimization measures near the slow circle point are proposed, and the accuracy and applicability of the method are proved by the shield tunnel between Wanchai North Station and Wanchai station of Zhuhai Zhuhai-mechanical line, which provides a theoretical basis for the control of segment assembly quality on the transition curve. [ABSTRACT FROM AUTHOR]