Construction method of multi-arch tunnel without middle wall

Abstract

The invention discloses a construction method of a multi-arch tunnel without a middle wall. The construction method comprises the steps of digging a right-side tunnel, performing primary supporting and secondary lining, constructing the external surface of a right-side tunnel early-period support to a step-shaped contact surface which is also a rough surface, pouring a reinforcing bar in each step, wherein one part of the reinforcing bar is poured in the early-period support and the other part is exposed to outside; digging a left-side tunnel, performing left-side tunnel early-period supporting and secondary lining; constructing the surface of the left-side tunnel early-period support to a step-shaped contact surface which matches the external surface of the right-side tunnel early-period support, thereby matching the step-shaped contact surface of the right-side tunnel, and fully pouring the reinforcing bars which is exposed to outside in a previous step into the left-side tunnel early-period support in injection; and forming an integral force bearing system. The construction method of the multi-arch tunnel without the middle wall has advantages of simple construction process, high speed and stable connection structure.

Description

technical field [0001] The invention relates to the construction field, in particular to a construction method for a multi-arch tunnel without a middle wall. Background technique [0002] When building expressways in mountainous areas, the lines often pass through passes, chicken feet, or lay lines along streams and valleys. The two ends do not require high terrain, occupy a small area, facilitate wiring, small wiring engineering, smooth linearity, and environmental protection, so they are favored by tunnel builders. [0003] The left and right sides of the traditional multi-arch tunnel share a middle wall, and the section form is "M" shaped. The difference in the structural form is mainly due to the different forms of the middle wall. According to the different section forms of the middle wall, multi-arch tunnels can be divided into straight middle wall type and curved middle wall type, and straight middle wall and curved middle wall can be divided into three categories: i...

AI Technical Summary

Problems solved by technology

[0006] (1) During the construction, the construction process of excavating the central pilot tunnel and support first, pouring the central wall concrete after the central pilot tunnel is penetrated, and then excavating the main tunnel, and the excavation section of the central pilot tunnel is small, and the construction work surface is narrow , coupled with many and cumbersome construction procedures, resulting in slow construction progress and even affecting the construction period

[0007] (2) There are many construction and excavation procedures, which lead to multiple disturbances to the surrounding rock, expanding the plasticity and relaxation range of the surrounding rock, and increasing the lining load

[0008] (3) It is difficult to control the compactness of the concrete at the top of the middle wall, and it is difficult to guarantee the construction quality

[0009] (4) The force transformation of the middle wall is complicated during the construction process

During the construction process, the middle wall bears the unbalanced pressure of the top support or the unbalanced thrust brought by the secondary lining, which is easy to cause the deviation and cracking of the middle wall, affecting the safe use and durability of the tunnel

[0010] (5) The deformation of the surrounding rock after the temporary support of the middle pilot tunnel cannot be restrained in time, resulting in the aggravation of the deformation of the surrounding rock, and prone to landslides and roof fall

[0011] (6) The intermediate pilot tunnel adopts temporary support, which needs to be removed when the main tunnel is excavated, resulting in a waste project, which is uneconomical

[0012] (7) Water leakage is prone to occur at the joint between the top of the wall and the main tunnel in integral and hollow double-arch tunnels with middle walls; water leakage phenomenon

[0013] Due to the complex structure of the multi-arch tunnel itself and the many construction procedures, the stress state of the structure changes frequently, and there are many and difficult quality control points. If there is a slight negligence, diseases will appear. At the same time, if the middle wall structure of the existing multi-arch tunnel is canceled There will be the disadvantage that the connection structure between the two arches is unstable and not firm. At the same time, the existing concrete has low strength and poor weather resistance, which will lead to cracking and other situations during long-term use.