Study On The Mechanics Character Of Shield Tunnel Segment With Shell-spring Model

With the development of economic and overall strength of the country, the climax of underground cavity of big and middle city is coming. The rate of development underground construction is faster, shield method is a mature engineering techniques which is used more and more abroad, so it's urgent to draft out a standard for shield tunnel tunneling. Because of lack of the standard for shield tunnel, the design of shield tunnel lining is blind, which doesn't take into account the reality of shield engineering in China. Without the guidance of the standard for shield tunnel, the results of shield tunnel lining lead to waste or haphazard of design. The results are not benefic to strategic implement of subway project of vital and lasting importance, can avoid haphazard design of shield lining. So the study for the design of shield lining is very valuable for academy and application, which has some guidance for designing shield segment in the aspects of security, economy and rationality.The most important problem of theory of shield segment design is whether the design model can reflect the practical stress of the segment. The models of cross structure for design calculations are classified by joint evaluations as follows: Usual calculation method, Modified Usual calculation method, Ring with multiple hinged joints calculation method and Beam-spring model calculation method. The longitudinal have two structure models, including longitudinal Beam-spring model and longitudinal equivalent rigidity model. All these models are simplify the segment as beam in cross or longitudinal direction. But shield tunnel is a round hole shape structure, and is made up of many segments, structure performance is quite complex. Reflect the structure performance between segment rings is difficult when simplify the segment as beam in cross direction or longitudinal direction. So it is difference from the mechanics character and structure performance of the shield tunnel. Development with the mature of design and construction, the width of segment is more and more wide, this time beam which simulating the segment can not reflect the practical mechanics character of the segment. And the longitudinal structure performance of tunnel is related to the cross structure performance of tunnel. With the alteration of the longitudinal structure performance of tunnel, the cross structure performance of tunnel also will change. But now all the models can only reflect the cross or longitudinal structure performance, and no model can reflect both the cross structure performance and longitudinal performance at one time.