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采取Lagrange差分法,用双弹簧单元模拟锚杆单元,对锚杆拉拔工况下的应力变形特征进行数值仿真计算。在锚头处锚杆轴力最大,沿着锚杆体呈现出逐渐减小的趋势。由于锚杆的拉拔,在其与土体之间产生相对位移,引起界面上产生相互摩擦力。由于锚杆与岩土体的相互作用,在锚头和锚尾部周边土体形成应力集中区域。随着拉拔位移的增大,锚杆的锚固力也不断增大。土体周围的压力越大,相同锚头位移所需的拉拔荷载越大。随着锚杆长度的增大,锚固系统能够发挥的极限锚固力也增大,二者呈线性关系。沿着杆体长度方向,锚杆的锚固力呈现非线性减小。
The Lagrange difference method is adopted to simulate the bolt unit by double spring unit, and the numerical simulation of the stress and deformation under the condition of bolt pullout is carried out. At the anchor head, the bolt axial force is the largest, showing a decreasing trend along the bolt body. Due to the pulling of the anchor rod, a relative displacement occurs between it and the soil body, causing mutual friction on the interface. Due to the interaction of rock bolt and rock mass, the stress concentration area is formed in the soil around anchor head and anchor tail. As the drawing displacement increases, the anchoring force of the anchor rod also increases continuously. The greater the pressure around the soil, the greater the pull-off load required for the same anchor displacement. With the increase of the length of anchor, the anchoring system can also exert the limit anchoring force also increases, the two linear relationship. Along the length of the rod body, the anchoring force of the bolt presents a nonlinear decrease.