煤巷锚杆-锚索支护的预应力协调作用分析

Pre-tensioned stress coordination function analysis of bolt-cable anchor support in coal roadway

在分析目前锚杆、锚索联合支护条件下施加预紧力时存在问题的基础上,提出了锚杆、锚索联合支护的预应力协调问题,并采用有限差分数值计算软件FLAC3D对锚杆(索)施加不同组合预紧力时围岩产生的应力场分布特征与规律进行了模拟分析。结果表明:预应力锚杆、锚索联合支护可以在巷道围岩锚固结构中形成相互连接、相互叠加的有效压应力区,随着锚杆(索)预应力的增加,压应力区的值和范围也相应地增加;锚杆端部的拉应力值和范围随锚杆预紧力矩的增加而增大,这种情况可以通过施加锚索预紧力进行平衡,锚杆预紧力矩越大,平衡其端部拉应力区所需的锚索预紧力越大;结合工程施工现状,合理的锚杆预紧力矩选择在300～400N.m,锚索预紧力为200～300kN比较合理。井下试验表明,合理预应力组合的锚杆锚索联合支护系统可以有效控制围岩变形。

Based on the analysis on existing problems of pre-tension inflicted bolt-cable anchor support,pre-stressed coordination function problem was put forward.The distribution features and law of the stress fields caused by the different combination pre-tension of bolts and cables were analyzed through finite difference numerical software FLAC3D.The results show that pre-tensioned stress bolt-cable support can cause interconnection and overlapping effective compressive zone in surrounding rock bolt-grouting body of roadway,and with the increasing of the bolt-cable pretension value,the value and scope of the compressive zone also increases;the tensile stress value and zone of the bolt head increases as the bolt pre-tightening torque,and the zone can be balanced by applying cable pretension,which increases with higher bolt pre-tightening torque.On the base of current situation of engineering construction,the reasonable combination value of bolt pre-tightening torque is between 300 and 400 N·m,and the cable pre-tension is between 200 and 300 kN.It is proved that the bolt-cable anchor support with reasonable pre-tensioned stress is suitable for control surrounding rock of coal mine.