围岩弹塑性变形条件下锚杆、喷混凝土和U型钢的支护效果研究

已给出弹塑性变形条件下围岩-支护相互作用的全过程解析求解,在此基础上深入研究3种常用支护结构的支护作用效果,是非常必要的。考虑开挖面空间效应,根据弹塑性变形条件下围岩-支护相互作用的全过程解析求解,针对6、5、4 m直径的工程算例,分别对素喷混凝土、锚杆和U型钢等3种支护结构的支护作用效果进行了理论计算与分析,主要包括:3种支护结构极限承载能力理论计算、基于开挖面空间效应的3种支护结构控制围岩弹塑性变形的理论计算与效果分析、剩余支护承载力对普氏围岩压力支护效果的计算与分析;研究了U型钢支架的荷载-径向变形本构关系、提出了剩余支护承载力的概念、分析了支护结构支护围岩各类形变压力的支护机制。研究结果表明:(1)3种支护结构能提供的支护承载力ip(<1 MPa)相对于原岩应力0p(>10 MPa)来说量级太低,控制5⁶ m及更大直径的巷道围岩弹塑性变形是无效的,但控制4 m直径的巷道围岩弹塑性变形是有效的;(2)对于直径达56 m及更大直径的巷道围岩弹塑性变形是无效的,但控制4 m直径的巷道围岩弹塑性变形是有效的;(2)对于直径达5⁶ m甚至更大的巷道围岩,若支护结构的剩余支护承载力i2p能有效地被保存,则支护结构还可以起到有效地支护普氏围岩压力的作用。

Support effects of anchor bolt,shotcrete and U-steel in elastoplastic stage of surrounding rock

Analytical solutions to the complete action process of surrounding rock-support in elastoplastic stage have been provided. Supporting structures of anchor bolt, shotcrete and U-steel are commonly used in the practical projects. It is a critical theoretical issue to further study the three supporting structures on this basis. Based on the spatial effects of the excavation face, and according to the analytical solutions above-mentioned, the supporting structures respectively through project examples in which the surrounding rocks have diameters of 6 m, 5 m, 4 m, is studied. And the thesis mainly includes three the following parts: calculations of ultimate bearing capacity of the above three structures, calculation and analysis about the effect on controlling plastic deformation of surrounding rock based on the spatial effects of the excavation face, and analysis of the supporting effect on the Protodyakonov's surrounding rock pressure by the remaining supporting force. It is also studied U-steel constitutive relationship between load and displacement, proposes conception of the remaining force and analyses the mechanism of supporting structure restricting deformation of surrounding rock. Two conclusions are drawn as follows. (1) Compared with the in-situ stress(>10 MPa), the supporting forces (<1 MPa) provided by the three supporting structures are too low to control the elastoplastic deformation of the surrounding rock with diameters of 6 m, 5 m or more larger, but the supporting forces are effective for the surrounding rock with diameters of 4 m . (2)For the the surrounding rock with diameters of 6 m and 5 m or more larger, if the remaining supporting force can be reserved effectively, supporting structure can support Protodyakonov's pressure availably.