基于完整锚杆动测技术的围岩质量识别研究

Identification of surrounding rock quality based on dynamic testing technology of integrated anchor

完整锚杆系统是由完整的锚杆杆体、饱满的锚固介质以及围岩组成的有机体系。在描述锚杆低应变动力响应的数学力学模型中,将锚固介质与围岩对锚杆体的作用简化为沿杆长均匀分布的杆侧弹性系数与阻尼系数,以及均匀分布在杆底的刚度系数与阻尼系数,即锚杆系统的动力参数。它们不仅表征了锚杆锚固质量,而且体现出锚杆所处围岩的物理参数。通过建立围岩物理参数与完整锚杆系统动力参数的映射关系,可以对围岩质量进行识别。为此,建立了完整锚杆三维轴对称有限元计算模型,得到不同的围岩物理力学参数所对应的锚杆杆顶速度响应;根据完整锚杆低应变动力响应理论解和遗传算法建立了完整锚杆动力参数的识别方法;通过对不同围岩下完整锚杆的数值模拟结果的动力参数识别,建立了杆侧弹性系数与围岩变形模量之间的关系式,提出了一种基于完整锚杆动测技术的围岩质量识别方法。

Integrated anchor system contains integrated bolt, full cement grouting and surrounding rock. In low strain dynamic response of bolt model, the action of cement grouting and surrounding rock on bolt can be considered as elastic and damping coefficients which distribute uniformly along bolt and stiffness and damping coefficients which distribute uniformly on the bottom section of it. These coefficients, named dynamic parameters, present anchorage quality, mechanical behaviors of surrounding rock are also presented. Based on the relationship between dynamic parameters of bolt system and physico-mechanical parameters of surrounding rock, the quality of surrounding rock can be identified. Three-dimensional axisymmetric calculation model is established by using finite element analysis. The velocity responses of bolt＇s top with different physico-mechanical parameters of surrounding rock are obtained. A method to identify the dynamic parameters of integrated anchor system is established based on theoretical solution of integrated bolt＇s dynamic response and genetic algorithm. The dynamic parameters of integrated bolt with different physico-mechanical parameters of surrounding rock are acquired; and the relation between bolt-side elastic coefficient and surrounding rock＇s modulus of deformation is established. A method to identify the quality of surrounding rock through dynamic testing based on integrated anchor system is put forward.