Prejudgment method for sinking of early support of tunnel and closed distance of inverted arch

Abstract

The invention discloses a prejudgment method for sinking of an early support of a tunnel and a closed distance of an inverted arch. The settling volume of the early support is predicted more accurately, so that a scientific basis is provided for deformation allowance design of the early support, and the tunnel is ensured to safely pass through weak surrounding rock sections such as Xigeda group strata and the like. The method comprises the following steps of obtaining tunnel construction parameters including a tunnel span B; arranging a displacement monitoring point at the top of the early support, and monitoring the sinking volume u of the early support; recording a distance x from the inverted arch to a tunnel face; and through monitoring data analysis, fitting a relational expression of the sinking volume of the early support and the closed distance of the inverted arch: u=ae(x / 2B)+b.

Description

Technical field [0001] The invention belongs to the technical field of railway engineering construction, and particularly relates to a method for predicting the initial support subsidence and invert closed distance of a tunnel in a weak surrounding rock in the Xigeda formation, so as to improve the safety of tunnel construction. Background technique [0002] In the context of the rapid development of the modern economy, along with the gradual increase in the development of the western region, the construction of railway transportation will surely take the lead. Railway tunnels in my country will pass through difficult and dangerous geologically complex mountainous areas. When the tunnel passes through weak surrounding rocks such as the Xigeda Formation, the initial support subsidence and deformation during the construction process are large, and the initial support inverted arch (steel frame + shotcrete) is closed , That is, the deformation can be stabilized after the initial supp...

AI Technical Summary

Problems solved by technology

The Xigeda Formation has the characteristics of being easily deformed when it meets water softening, and the structure is damaged and loses its strength. If the initial support stiffness is insufficient, it is easy to cause a large displacement of the initial support and encroach on the limit, resulting in an increase in the cost of treatment measures, affecting the construction period and other adverse consequences

[0003] At present, there are many treatment measures and passive monitoring and measurement for the large deformation of the initial support of soft rock tunnels, but there is a lack of research on active prediction methods for the initial support settlement of tunnels with soft surrounding rocks, and there is no method for predicting the initial support settlement.

This has brought great difficulties to the design and reinforcement of the initial support of the weak surrounding rock strata. It often occurs that the initial support has too much subsidence, which leads to the trouble of encroaching and replacing it, which will inevitably affect the weak surrounding rock. have a major impact on the reliability and safety of tunnel construction

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