地应力作用下裂隙对锚杆预应力扩散机制的影响

为深入了解裂隙对锚杆预应力扩散机制的影响,采用将锚杆预应力在裂隙围岩中形成的应力场-锚杆预应力场从围岩应力场中分离出来的方法,系统地研究了地应力作用下裂隙位置、长度和倾角对锚杆预应力扩散机制的影响。研究发现:裂隙长度对锚杆预应力场的影响最显著、次为倾角、再次为位置。裂隙长度存在阈值;随其长度增加,拉、压应力峰值区位置发生转移,拉应力峰值单调增加,压应力峰值则先增大再减小。随裂隙向围岩深部移动,拉、压应力区位置发生互换,拉、压应力峰值总体呈减小趋势。裂隙倾角90°时的锚杆预应力场与30°~75°时的显著不同;随裂隙倾角增大,拉应力峰值按减小→增大→减小的规律变化,压应力峰值先减小再增大。

The influence of the fracture on the diffusion mechanism of bolt pre-stressed field under the ground stress function

In order to thorough understand the influence of the fracture on distribution of bolt pre-stressed field area (BPFA, the stress field in the surrounding rock induced by the pre- tensioned bolt), a new method, separating the bolt pre-stressed field from the rock stress field, was put forward. Based on this method, the influence of the fracture on the BPFA was systematically studied under the ground stress function. The results showed that the fracture length influence on the BPFA was the most significant, the dip angle second and the position least. Besides, the fracture length had threshold value. As the fracture length increased, the positions of compressive and tensile peak stress area shifted, at the same time, the tensile and compressive stress peak increased monotonically and firstly increased and then decreased, respectively. With the fracture moving towards to the depth of the surrounding rock, the compressive and tensile peak stress area exchanged their positions, the compressive and tensile peak stress tended to decrease. The BPFA of fracture with dip angle of 90° had a significant difference with those of dip angle of 30-70°. With the dip angle increasing, the tensile peak stress decreased at first, then increased, and finally decreased, while the compressive peak stress at the beginning decreased and then increased.