Calculation model of shotcrete support thickness based on elastic thin plate theory

Abstract

In order to accurately calculate the thickness of shotcrete in tunnel, the support load, inter-anchor row distance and concrete mechanical properties are selected as influencing factors, and a mechanical model of shotcrete support thickness is established based on the elastic thin plate theory to derive the relationship between support load, inter-anchor row distance, concrete mechanical properties and concrete thickness. The controlled variable method (CVM) was used to study the variation law of support load and inter-anchor row distance with concrete thickness. The results show that: the mechanical properties of the concrete slurry remain unchanged, the required thickness of the concrete support increases with the increase of the support load, in a power of 1/2 relationship, with the increasing thickness of the shotcrete, the concrete is prone to shear damage to tensile damage until the thickness meets the engineering requirements; the support load remains unchanged, the thickness of the concrete support is linearly related to the anchor rod spacing, with the increase of the anchor rod spacing As the anchor spacing increases, the required thickness of concrete support also increases linearly. This paper successfully defines the relationship between the required concrete support thickness, support load and anchor rod parameters for shear and tensile damage, and through the analysis of the anchor spraying case, it is believed that the calculation model is reasonable and the results can provide a theoretical basis for the quantitative design of the support system.