Study On The Support Effects Of Bolt's Surface Protecting Components In Large Deformation Roadway

Bolt is a type of 'inside support' in the interaction system of 'bolt-rock', Its function lies in improving the mechanical property and stress status of surrounding rock, consequently turning the passive rock into active carrying structure, received extensive application. However, the simple bolt supports can't prevent the surrounding rock's weathering and desquamate. Bolt support will lose efficiency in the situation that rock relaxed and deformation. So, bolt should cooperate with other measures formed into 'bolt + surface protecting component' supporting mode. Cooperating with steel band, metal network, truss etc. to expand its range of application and improving support effect. These bolt surface protecting components can not only protect surface rock of roadway, control the large deformation of surrounding rock, but also reduce the space of bolts, speed up the roadway's excavation.Bolt's surface protecting components include plate, steel band, metal network, truss, etc. It can overcome bolt's weakness, enhance support effects. The function of the surface protecting components can't be ignored, but the degree of attention to surface protecting component of the bolt is not high at home and abroad at present, the interaction of bolt components and rock protect mechanism is still at perceptual knowledge stage. This article used theory analysis, numerical simulation calculation, and on-the-site real example materials, etc. According to the bolt mechanism, researched the effects of plate and steel band in surface protecting and operation of anchor force exertion. Firstly, this article analyzed the surface protecting components' effect and current situation; Secondly, combined bolt neutral point theory, analyzed the plate's effect on the distributing of bolt axial stress and bond stress, calculated the plate's against force; Then analyzed the interaction of steel band and surrounding rock in detail, used FLAC^2D to numerical simulation the steel band and bolt supporting , and researched some parameters of steel band that affect support result; Finally, according to the strong...