锚杆支护巷道顶板稳定性动态可靠性分析

Dynamic reliability analysis on roof stability of bolting support roadway

在地下巷道工程中,由于岩体的流变特性给巷道围岩控制带来困难,在锚固围岩体中,锚杆长期有效的预应力是关系到巷道能否在服务期内保持稳定的关键之一.针对巷道开挖后,围岩体的长期流变导致锚杆支护系统失效,从而影响巷道不稳定甚至是破坏的现象,基于预应力变化值不应大于锚杆设计轴向拉力值的10%的规定,首先采用流变理论推导了基于鲍埃丁-汤姆逊流变模型的微元体锚杆轴力随时间变化的关系式,然后又对某具体回采巷道锚杆支护结构的动态可靠性进行了计算分析.结果表明,在回采巷道服务期间内,预应力随时间延长而不断降低,而且减小的速度变慢,最后逐渐趋于稳定,预应力变化值在允许的变化范围10%以内,因此,可认为巷道所采用的锚杆支护参数是可靠的,巷道在其服务期内是安全可靠的,该研究工作对指导煤矿巷道锚杆支护设计具有一定的理论和实际意义.

In the underground roadway engineering, owing to rheological properties of rock mass that have brought difficulty on surrounding rock control of roadway, among anchorage surrounding rock mass, bolting long - term effective pretension is one of the key factors related to keep stable or not in service period of roadway. In allusion to roadway excavation, long term creep of rock mass lead to failure of bolting system, moreover affecting instability or failure of roadway, based on provisions that the change value of pretension should not exceed 10% than the design axial tension value of bolting, firstly to derive the relationship that bolt axial force of small element of Poyting - Thomson rheological model along with time by using theological theory, and then to carry on calculation and analysis of bolting bearing reliability in specific bolting support structure of roadway. Results show that, in the service period of roadway, pretention continuous decrease along with time, and decrease speed to slow down, and finally tend to be stable, pretension change value in the allowed range 10% , therefore, bolting support parameters of roadway can be considered to be reliable, the roadway can be safe and reliable in its service period, and the research work has a certain theoretical and practical significance to guide bolting support design of coal roadway.