不同预紧力锚杆锚索对围岩支护应力场影响研究

Study on Anchor Bolt and Anchor Wire of Different Pre-tightening Force Influences on Encircling Rock Supporting Stress Field

针对不同预紧力情况下锚杆锚索对围岩支护应力场的影响进行了研究,得出了几点重要结论:随着锚杆锚索预紧力的增加,巷道周围有效压应力区呈现逐步扩大的趋势,同时锚固范围之外的应力降低区也随着预紧力的增加而扩大。在同一预紧力情况下,锚杆的自由段轴力大小可以视为均匀分布,但在锚固段部分,由于预紧力的损失,在很短距离范围内,锚杆轴力明显减小,直至减小为0。对锚索施加预紧力时,锚索尾部附近均出现了明显的应力集中。在同一预紧力情况下,锚索距离顶板越远,最大主应力越小。在不同预紧力下,在同一距离处,预紧力越大,最大主应力也将越大。

Mainly studies the anchor bolt and anchor wire of different pre-tightening force which have influences on encircling rock supporting stress field, and draws some important conclusion:with the increase of anchor wire's the pre-tightening force, the effective compressive zone enlarges gradually in tunnel adjacent rock, meanwhile the stress-relaxed area which is outside the scope is expanding. In the condition of the same pre-tightening force, the axial force on free part of the anchor bolt can be regarded as uniform distribution,but in the anchoring section, due to the loss of pre-tightening force,bolt axial force significantly reduces until extinction across small distances. When exerting pre-tightening on anchor wire, there is an obvious stress concentration on the end of the anchor wire. In the condition of the same pre-tightening force, the greater distance between anchor wire and roof is, the smaller maximum principal stress is. In the condition of different pre-tightening force, at a certain distance, the bigger the pre-tightening force, the greater the maximum principal stress will be.