Rosenblueth方法在软破围岩锚喷支护系统评价中的应用

软破岩的特点是成分复杂 ,裂隙发育 ,含有膨胀性矿物。在软破岩中的巷道围岩的地压是变形压力 ,它首先表现为侧壁岩体鼓胀成楔形被挤出。这种现象与Rabcewicz提出的软岩剪切滑移理论基本吻合。对这类围岩最为有效的支护形式是锚喷支护 ,由于软破岩的特点和复杂性 ,其本身和锚喷支护结构的力学参数和失效机理存在不确定性。对这类地下结构的稳定性分析时最为合适的是采用能考虑不确定性的可靠度方法。在建立可靠度方程时 ,按照该类岩体的地压特点 ,将承载结构分成两个子结构 ,根据子结构变形特点和受力条件建立结构总体极限状态方程。由于总体极限状态方程是在圆形巷道的基础上建立的 ,因此在文中还给出了一般形状巷道转化为等代圆形巷道时其半径的四种计算方法。最后给出了一个工程算例。

Application of Rosenblueth method in evaluating stability reliability of anchor-shotcrete net support system for soft-fractrue surrounding rock

The characteristic of soft-fractrued rock mass is that its component is complex,fissure is well developed and there is dilatant mineral.Underground pressure of surrounding rock mass of roadway in soft-fractrue rock mass is mainly deformation pressure.Underground pressure emerges that side wall rock mass of roadway swells to be a wedge and is squeezed out at first.The phenomenon basically is in accordance with shear slide theory proposed by Rabcewicz.The most effective support to soft-fractured rock mass is anchor-shotcrete net support,but there is uncertainty in parameters and failure mechanism of anchor-shotcrete net support structure due to the characteristic and complexity of soft-fractrued rock.The reliability method that can take uncertainty into account is the most appropriate way to analyze stability of the support structure.With the reliability equation established,load bearing structure of anchor-shotcrete net is divided into two sub-structure according to underground pressure of the soft-fractrued rock mass,and general limit state equation is established based on deformation of sub-structure and its load bearing condition.Since the general limit state equation established is based on circular section,four calculation methods with section of roadway changed into equivalent circle section are put forward.An engineering example is also given.