爆炸荷载作用下锚固洞室的损伤演化及锚杆参数的影响

The damage evolution and influence of bolt parameters of tunnels reinforced by rockbolts under blast loads

基于模型试验的结果,利用数值分析方法研究了锚固洞室在爆炸荷载作用下的损伤演化过程,并探讨了锚杆间距和长度对地下洞室稳定性的影响。结果表明:数值分析和模型试验中相同位置的压应力时程曲线相似且数值分析的损伤分布和试验结果中的裂纹区域相同,证明数值分析中的数据比较可靠。随着爆炸应力波的传播,在锚固洞室的拱顶中间自由面和拱顶加固区边界形成较大拉伸损伤区域。随着锚杆长度的增加,拱顶中间自由面附近最大损伤区域向拱顶上方发展,逐渐增加;拱顶加固区边界的最大损伤区域向洞室自由面方向发展,并且两边的损伤区域厚度逐渐减小。当锚杆间距相同时,随着锚杆长度的增加,拱顶中间自由面和拱顶加固区边界的最大拉伸损伤区域先减小后增加;当锚杆长度相同时,随着锚杆间距的减小,中间自由面和拱顶加固区边界最大拉伸损伤区域面积逐渐减小,并得到最佳锚杆间距和长度分别为4cm和24cm。

Based on the results of model tests, the process of damage evolution is studied by numerical analysis, and the influence of bolt spacing and length on the stability of underground caverns is discussed. By comparing the results of numerical analysis and model experiment, it is found that the time history curves of compressive stress at the same position in numerical analysis and model experiment are similar, and the damage distribution of numerical analysis is the same as that of crack area in experimental results, which proves the data of the numerical analysis are reliable. With the propagation of the explosion stress wave, a large tensile damage zone is successively formed in the upper part of the anchor cavity and in the middle of the floor. With the increase of the length of the bolt, the damage area near the middle free surface of the dome develops to the top of the dome and gradually increases. The maximum damage zone at the boundary of the reinforced area develops toward the free surface of the cavern, and the thickness of the damage zone on both sides gradually decreases. When the bolt spacing is the same, with the increase of the length of the bolt, the maximum tensile damage area in the anchorage zone and its vicinity will decrease first and then increase. When the bolt length is the same, with the decrease of the bolt spacing, the area of the largest tensile damage zone in the anchorage zone and its vicinity gradually decreases. The best anchor spacing and length are recommended respectively for the special case studied in this paper.