Abstract
In order to clarify the influence of anchor bolts on the supporting effect of the layered weak roof and surrounding rock of nonlayered roof with good integrity, the mechanical model of the roadway with nonlayered homogeneous roof and layered weak roof was established using FLAC3D. The distribution characteristics of the stress field and the displacement field of the bolt support are analyzed, and the supporting effect of the bolt on the roof of two types of roadways is studied. The research results show that when the original rock stress is not considered, the bolt support shows obvious tensile, compressive stress areas and positive and negative displacement areas in the surrounding rock of the roof of the roadway; when the original rock stress is taken into account, the tensile and compressive stress zones and the positive and negative displacement zones of the anchor support in the surrounding rock of the roof plate disappear obviously. The effect of the bolt support on the stress field and plastic area of the surrounding rock of the two types of roadway roof is not obvious. However, it has a significant effect on suppressing discontinuous deformation such as delamination and sliding between layered roof rocks. The delamination phenomenon between rock layers disappeared obviously, and the range of each numerical curve of the displacement field of the surrounding rock in the anchoring area was significantly reduced. However, the effect of the anchor support on continuous deformation control such as elastoplastic deformation of roof rock of nonlayered roadway is very limited. There is almost no change in the displacement field curve in the depth of the roof‐surrounding rock. Only the shallow surrounding rock displacement field curve range has decreased.
Highlights
With the exploitation of resources and continuing energy development, the roadways surrounding mechanical rock environments are becoming increasingly complex, typically exhibiting engineering response characteristics such as large nonconforming deformations and large-scale unstable failure
After excavation of the roadway, the deformation energy in the shallow surrounding rock can be released before the bolt support is applied, and the roadwaysurrounding rock will inevitably move into the excavation space. is will result in a certain amount of internal displacement, which mainly includes continuous deformation due to elastic deformation and plastic deformation, discontinuous deformation such as bed separation, and sliding and crack opening of the surrounding rock structural plane in the soft rock and the fractured zone
FLAC3D is a numerical simulation application based on continuum theory. erefore, the deformation of surrounding rock in nonlayered homogeneous roofs was considered in terms of elastic deformation and plastic deformation, that is, continuous deformation. e deformation of the roadway-surrounding rock of layered roofs includes elastic deformation and plastic deformation, and open sliding deformation between the weak faces of the roof, that is, discontinuous degeneration
Summary
With the exploitation of resources and continuing energy development, the roadways surrounding mechanical rock environments are becoming increasingly complex, typically exhibiting engineering response characteristics such as large nonconforming deformations and large-scale unstable failure. Kaya et al established a numerical finite element method (FEM) model based on Advances in Civil Engineering engineering geological surveys and based on the lithology and structural characteristics of the tunnel and studied the effect of bolt support on the total displacement and size of the plastic zone on the roof [6]. Based on field simplified model tests and numerical simulations, Han et al studied the effects of anchor length, anchoring direction, and bolt spacing on the bearing characteristics of soft-sand, soft rock tunnels [16]. E above-mentioned studies mainly focus on the control of the roadway-surrounding rock using bolts from the aspects of prestressing, the anchoring agent, anchor strength, stiffness, and support density and have not fully considered the influence of the structural features of the rock surrounding the roadway roof on the bolt support. E effects of the bolts on the stress field, displacement field, and plastic zone of the surrounding rock are studied for nonlayered homogeneous roofs with good surrounding rock and layered roadways with good integrity. e problem of the anchoring mechanism of the surrounding rock support in the two types of coal mine roadway roofs is discussed
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