基于非线性统一强度的锚索极限抗拔力的计算

Calculation of Ultimate Pullout Force of Cable Based on Nonlinear Unified Strength Criterion

以非线性统一强度理论为基础,充分考虑岩体的中间主应力效应和岩体强度的非线性特性,并结合锚索的破裂面形状和极限平衡原理,获得了一个应用于地下硐室的预应力锚索极限承载力的计算公式。该公式能综合考虑岩土体种类、无侧限抗压强度、锚索倾角和注浆压力等各方面因素对锚索极限抗拔力的影响。最后给出了一个计算实例。结果表明,计算得出的锚索极限抗拔力大于传统设计应力,与实际工程更为接近,可充分发挥材料的强度潜能;随着中间主应力影响系数的增大,锚索的破裂面临界高度基本不变,而其极限抗拔力非线性增长;随着注浆压力的增大,锚索的破裂面的临界高度和极限抗拔力都呈线性增长。

Based on the nonlinear unified strength theory of rock,fully considering the effect of intermediate principal stress and nonlinear characteristics of rock strength,according to the rupture shape of cable and limit equilibrium principle,a formula for the ultimate bearing capacity of pre-stressed cables in underground chambers was derived,in which the influences of rock types,unconfined compressive strength of rock,dip angle of cable and grouting pressure on the ultimate pullout force of pre-stressed cable can be synthetically considered.A calculation example was given.The result showed that calculated ultimate pullout force is greater than the value of conventional design and more suitable for practical engineering,so the strength potential of materials can be utilized more fully;with the increase of the influence coefficient of intermediate principal stress,the ultimate pullout force of cable increases nonlinearly,but the critical height of fracture surface of cable is almost invariant;when the grouting pressure increases,the ultimate pullout force of cable and the critical height of fracture surface of cable increase linearly.