A Design Method of Composite Lining Structure of Tunnel with Load Acting on Ground Boundary

Abstract

The invention discloses a method for designing a tunnel composite lining structure with the load acting on stratum boundaries. By the adoption of the method for designing the tunnel composite lining structure with the load acting on the stratum boundaries, a more reasonable and more economical tunnel lining structure can be designed, a large amount of lining concrete masonry can be saved, the use amount of steel bars can be reduced greatly, and the construction cost of a tunnel is effectively reduced. The method for designing the tunnel composite lining structure with the load acting on the stratum boundaries comprises the steps that basic parameters required by designing are determined; the load of the tunnel is calculated; a design method model is established, surrounding rock is simulated with a two-dimensional solid structure unit, a plane strain model is selected to serve as the design model, the composite lining is supported preliminarily and a beam unit used for secondary lining is simulated according to the elastoplasticity constitutive relation, a chain rod unit for a waterproof layer is simulated, and the chain rod unit is only under the action of pressure; meshing is conducted, wherein the preliminary support and the second lining are divided through mapped meshing; the lower boundary of the surrounding rock is constrained, so that it is guaranteed that rigid body displacement does not occur; the pressure of the surrounding rock acts on the upper boundary, the left boundary and the right boundary respectively; the soil body in the center of the tunnel is excavated for calculation, and the internal force and deformation during preliminary support and second lining are extracted respectively; the reasonable lining thickness and the reasonable reinforcement ratio are designed according to an internal force deformation result during preliminary support and second lining.

Description

technical field [0001] The invention relates to tunnels, in particular to a tunnel composite lining internal force design method in which loads act on stratum boundaries, and can be widely applied to the composite lining structure design of tunnels excavated in railways, highways, hydraulic engineering and subways. Background technique [0002] Tunnel lining is the main structure of tunnel engineering, and it is also the main research and design object of tunnel engineering. At present, most of the tunnels at home and abroad are designed and constructed according to the theory of the New Austrian Method, and the composite lining as its main supporting structure is born corresponding to the concept of the New Austrian Method, and the composite lining design of most tunnel projects is only For the secondary lining in the supporting structure, the load-structure method commonly used in the engineering field is adopted to allow the lining to bear the active and passive loads fro...

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Problems solved by technology

[0003] However, both in theory and in engineering application, the load-structure method has great disadvantages, and is obviously unreasonable and uneconomical.

Since the new Austrian method is based on rock mechanics, it is necessary to fully consider the interaction between the surrounding rock and the support. The surrounding rock is no longer regarded as a load alone, but as a component of the support system, like the load-structure method. This kind of calculation only for the secondary lining without considering the surrounding rock is contrary to the new Austrian method. The load-structure method uses elastic support to simulate the restraining effect of the surrounding rock on the support deformation, which is quite different from the actual situation. It truly reflects the interaction between surrounding rock and support. After long-term observation and engineering practice, it has been shown that the bearing capacity of the initial support designed by the load-structure method is underestimated, and an overly conservative secondary lining structure is often designed. The secondary lining has a large Surplus safety, resulting in waste of building materials such as masonry and steel bars, and poor social and economic benefits

[0004] With the development of social economy and technological progress, there are more and more applications of high-speed and long-span railway tunnels, and the performance of building materials has also been greatly improved and improved. The tunnel diameter, lining thickness and overall performance have all changed greatly , from the perspective of economy and rationality, the original load-structure method can no longer adapt to the current technological and social economic development, and it is necessary to make inventions and innovations in design methods

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