锚杆动静耦合力学性能与抗冲机制

Mechanical properties and impact resistance mechanism of anchor bolts under dynamic-static coupling conditions

  • 摘要: 锚杆支护是深部地下工程常用的围岩控制技术。为对深部复杂条件围岩进行安全控制,需对锚杆施加预应力,同时受到围岩大变形、开采扰动和强冲击等影响,使锚杆处于动静耦合的工作状态。因此,研究锚杆在不同工作荷载状态下的抗冲性能与安全储备对深部地下工程支护设计至关重要。基于此,利用自主研发的锚杆动静耦合力学性能试验系统,开展了现场常用普通锚杆与高强锚杆在0~200 kN初始荷载条件下的动静耦合力学性能试验,明确了锚杆动静耦合力学性能与抗冲吸能特性。结果表明:在冲击能量方面,动静耦合条件下不同锚杆抵抗的冲击能量随初始荷载的增大具有相同的衰减规律。在吸收能量方面,锚杆吸能能力为固有属性,未随外部荷载条件改变而显著改变。同时,锚杆单次吸收能量随着初始荷载的增大而增大,导致了锚杆冲击能量显著下降,安全储备降低。在0~200 kN初始荷载条件下,普通锚杆与高强锚杆的冲击能量衰减率最大分别为58.8%、50.0%,二者吸收总能量的均值分别为13.0×104、14.4×104 J,吸能系数随着强度利用率增加均呈现先缓慢、后快速的“阶段性增长”特征。通过综合分析,明确了锚杆动静耦合抗冲吸能机制,提出了锚杆动静耦合强度−能量设计理念,建立了动静耦合条件锚杆预应力“双折线”设计模型,可为深部地下工程动力灾害安全控制提供新思路。

     

    Abstract: Anchor bolt support is a commonly used surrounding rock control technology in deep underground engineering. To control the large deformation of surrounding rock under complex conditions, high prestress needs to be applied to the anchor bolts. Meanwhile, affected by mining disturbances, strong impacts, etc., the anchor bolts are in a working state of dynamic-static coupling. Therefore, studying the impact resistance performance and safety reserve of anchor bolts under different working load conditions is crucial for the support design of deep underground engineering. Based on this, the multi-functional dynamic-static coupling test system is self-developed. The dynamic-static coupling mechanical performance tests on Common Bolts (CB) and High-strength Bolts (HB) are conducted under initial forces of 0-200 kN. The dynamic-static coupling mechanical properties and impact resistance mechanism of anchor bolts are clarified. The test results show that: In terms of impact energy, under dynamic-static coupling conditions, the impact energy resisted by different anchor bolts exhibits the same attenuation law with the increase of initial force. In terms of energy absorption, the energy absorption capacity of anchor bolts is an inherent property and does not change significantly with load variations. Meanwhile, the single energy absorption of anchor bolts increases with the increase of initial force, resulting in a significant decrease in impact energy and a reduction in safety margin. Under initial forces of 0-200 kN, the maximum impact energy attenuation rates of CB and HB are 58.8% and 50.0%, respectively; the average total energy absorbed by CB and HB is 13.0×104 J and 14.4×104 J, respectively. The energy absorption coefficient demonstrates a “phased growth” characteristic of slow increase followed by rapid increase as the strength utilization rate increases. By comprehensive analysis, the impact-resistant and energy-absorbing mechanism of anchor bolts is clarified under dynamic-static coupling conditions. On this basis, the strength-energy dynamic-static coupling design concept for anchor bolts is proposed, and the bilinear prestress design model of anchor bolts under dynamic-static coupling conditions is established, which can provide new ideas for the safety control of dynamic disasters in deep underground engineering.

     

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