岩石锚固的机理(Physical Mechanisms of Rock Bolting)
1 引言
尽管有多种具体的锚固形式, 但作用和意图是锚固不稳定的岩块. 本文简要描述一些常用的锚固机理. 其中一些机理同时适用于地下开挖和边坡, 而另一些机理则主要适用于地下开挖.
2 锚固机理
(1) 最古老的锚固机理是悬吊作用. 锚固端深入到坚硬的岩层内。这个机理也适用于边坡. 实践中出现的问题是能否找到这样坚硬的岩层来支撑顶板或坡体滑动.
(2) 把岩层串起来形成一个更厚的梁,从而使其惯性矩、刚度和强度增加. 多年前我们曾经借助这种机理加上悬吊机理使用管缝式锚杆(Split-Set)支护一个煤矿巷道, 基本上不成功, 主要失败原因是锚杆长度(1.8m-2.2m)设计得太短, 导致整个锚固层全部塌落下来.
(3) 楔型效应。岩石或岩石楔形体被锚固在一起，从而产生摩擦和互锁作用。多伦多大学岩石工程组曾经对这种锚固效应做过一个非常有趣的相似材料试验. 我们将在以后详细讨论这个实验.
(4) 拱形效应. 锚固在开挖周围形成拱形。
3 不同应力水平的锚固
总的来说,在低应力水平的区域开挖所需的支护材料较少,在高应力水平的区域开挖需要的材料较多, 因此弄明白一个区域的原岩应力是非常重要的.
4 参考文献
[1] Carranza-Torres, C. (2009). "Analytical and Numerical Study of the Mechanics of Rockbolt Reinforcement around Tunnels in Rock Masses." Rock Mechanics and Rock Engineering 42(2): 175-228.
[2] Hyett, A.J., Bawden, W.F. and Coulson, A.L. 1992. Physical and mechanical propertiesof normal Portland cement pertaining to fully grouted cable bolts. In Rocksupport in mining and underground construction, proc. int. symp. rock support,Sudbury, (eds. P.K. Kaiser and D.R. McCreath), 341-348. Rotterdam: Balkema.
[3] Tyler, D.B., Trueman, R.T. and Pine, R.J. (1991) Rockbolt support design using a probabilistic method of key block analysis. In Rock mechanics as a multidisciplinary science, (ed. J.C. Roegiers), 1037-1047. Rotterdam: Balkema.
[4] Kaiser, P.K., Yazici, S. and Nosé, J. 1992. Effect of stress change on the bond strengthof fully grouted cables. Int. J. Rock Mech.. Min. Sci. Geomech. Abstr. 29(3), 293-306.
[5] Scott, J.J. 1983. Friction rock stabilizer impact upon anchor design and ground control practices. In Rock bolting: theory and application in underground construction, (ed. O. Stephansson), 407-418. Rotterdam: Balkema.
[6] Windsor, C.R. 1992. Cable bolting for underground and surface excavations. In Rock support in mining and underground construction, proc. int. symp. on rock support, Sudbury, (eds P.K. Kaiser and D.R. McCreath), 349-376. Rotterdam: Balkema.
[7] Yazici, S. and Kaiser, P.K. 1992. Bond strength of grouted cable bolts. Int J. Rock Mech. Min. Sci. & Geomech. Abstr. 29(3), 279-292.
[8] Hutchinson, D.J. and Diederichs, M.S. 1996. Cablebolting in underground mines.Vancouver: Bitech.
[9] Stillborg, B. 1994. Professional users handbook for rock bolting, 2nd edn. ClausthalZellerfeld: Trans Tech Publications.
相关文章：
岩土边坡的破坏类型(C3)(Failure types of slope)
岩石锚杆和锚索(Rockbolts and Cables)
原岩应力(in-situ stresses)的估算
构造控制的隧道稳定性分析---Rock Wedge
地下开挖/隧道岩体破坏模式的确定(EXCEL解）
