隧道径向锚钉-斜交锚杆复合支护技术研究

Study on Tunnel Composite Supporting Technology with Short Radical Anchors & Long Sloping Bolts

基于长短锚杆组合支护理论,提出了一种隧道径向锚钉-斜交锚杆复合支护技术,该技术可提高支护结构的整体抗力,有利于缩小围岩塑性区半径,增加锚杆处于稳定围岩区的长度。为进一步研究锚钉和锚杆的组合长度,将隧道围岩划分为A、B和C三区,并把锚杆作用在围岩体内的剪应力简化为环向边界应力,运用厚壁圆筒弹塑性理论推导了锚钉和锚杆组合长度计算式。实例分析表明,0.8m(锚钉)和3.8m(锚杆)的组合长度可以使隧道塑性区半径降低28%,锚固盲区减小88.8%。可见,在隧道长短锚杆组合支护理论中,该计算方法对围岩锚固体长度参数设计有一定指导意义。

This paper presented a kind of tunnel composite supporting technology with the combination of short radical anchors and long sloping bolts on the basis of the existing composite supporting theory. The technology can improve the overall strength of supporting structure,reduce the radius of plastic zone of surrounding rock and increase the anchor length in stable surrounding rock. In order to optimize the composite length of anchors and bolts,the rock body was divided into three regions called as A,B and C. Furtherly,the shearing strength acting on surrounding rock was simplified as toroidal strength. So we could use the thick wall cylinder elastic-plastic theory to deduce out the calculative formula of combined length. Through the example analysis,such combined length like 0.8m（ short anchors）and 3.8 m（ long bolts） can make a reduction by 28% for the radius of tunnel plastic zone,and by 88.8% for blind anchorage zone. So,it has a certain guiding significance for the design of anchors and bolts composite length.