Primary support opportunity selection method based on simulation analysis of tunnel excavation numerical value

Abstract

The invention discloses a primary support opportunity selection method based on simulation analysis of a tunnel excavation numerical value. The method comprises following steps: 1, establishing a two-dimensional numerical value model of a tunnel, and determining to use a excavation load release rate as the primary support opportunity r0 of the two-dimensional numerical value model of the parameter by utilizing a generalized virtual force support method; step 2, establishing a three-dimensional numerical value model of the tunnel, carrying out gradual excavation according to a certain reasonable excavation footage, and counting a displacement value of a typical position of a surrounding rock in a propulsion process of a tunnel face; and step 3, establishing a function relationship between the two-dimensional numerical value model and the three-dimensional numerical value model based on the concept of a displacement completion rate, and proposing an optimal primary support opportunity selection method of the three-dimensional numerical value model utilizing the tunnel face and the distances between monitoring sections as the parameters. By adopting the method disclosed by the invention, the primary support opportunity can be quantitatively calculated, the problem of determining the primary support opportunity by experience at present is solved, the distance from the tunnel face is used as the parameter of the calculation result, and the parameter can be used in practical engineering.

Description

Technical field [0001] The invention relates to the technical field of tunnel numerical simulation analysis, in particular to a method for selecting the timing of initial support based on the numerical simulation analysis of tunnel excavation. Background technique [0002] With the development of rock theory and numerical simulation methods, tunnel excavation is increasingly using numerical simulation for research and analysis. Under normal circumstances, the rock mass is affected by various natural stresses, construction methods and technologies, and the surrounding rock is easily damaged during tunnel excavation. According to the literature, most tunnel accidents occur within a short period of time after the excavation. At this time, the surrounding rock mainly depends on its self-supporting capacity and initial support to ensure its stability, so the initial support is very important. However, according to the New Austrian Methodology theory, if the support is too early, the ...

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Problems solved by technology

At present, the method for determining the timing of primary support in 2D numerical simulation generally adopts the generalized virtual force support method, but 2D numerical simulation is an ideal assumption for 3D problems, which can no longer meet the needs of engineering and academic research; while the primary support method in 3D numerical simulation There is still a lack of research on the timing, and it is generally operated by engineering experience or engineering analogy, and no effective and feasible control conditions or calculation methods can be proposed

[0004] Therefore, there are problems in the existing calculation method of initial support timing: (1) The initial support timing calculated in two-dimensional numerical simulation is based on the excavation load release rate parameter, which cannot be applied in actual engineering; (2) In 3D numerical simulation, the initial support timing is mostly selected based on experience, the selection methods have no commonality, and the principle of value selection is not clear; (3) effective and feasible selection methods and theoretical formulas have not been proposed

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