爆破荷载下岩质直立边坡预应力锚板墙动力响应机理

以重庆沙坪坝铁路枢纽综合改造工程开挖形成的岩质直立边坡为原型,利用FLAC3D软件建立数值计算模型,分析预应力锚板墙边坡支护结构在不同开挖位置的爆破荷载作用下的动力响应特性。在此基础上,讨论锚杆预应力大小、爆破峰值荷载和锚固段长度几种参数对于支护结构受力状态和结构变形的影响。计算结果表明:爆破作用下锚杆轴力增量分布与静力作用下相似,并且锚杆轴力增量和板墙位移都在边坡中部达到最大,而上下位置较小。对比锚杆轴力增量和板墙水平位移增量的数值模拟和理论计算结果,验证了板—锚结构之间存在的变形协调现象。通过各种影响因素的计算结果分析得到了岩质边坡预应力锚板墙支护在爆破作用下的动力变化规律。

Dynamic Analysis of the Vertical Slope with Pre-stress Anchor Wall under Blasting Seismic Wave

According to the prototype of a vertical rock slope formed by an excavation in the railway hub comprehensive renovation project of the Shaping Dam in Chongqing in China, this study developed a calculation model using FLAC3D. The dynamic response characteristics of different excavation positions under the effect of explosion loading were analyzed. Furthermore, the effects of different parameters, including the size of prestress, blasting peak load, and anchor length, are discussed. The results show that the pre-stress anchor axial force increment schedule and the horizontal displacement increment schedule in the slope-supporting structure under blasting both experienced three stages, namely, start of growth, stable growth, and growth accumulation. The anchor bolt axial force and the wall displacement reached the maximum value in the middle of the slope, but reduced at the top and bottom of the slope. The phenomenon of compatible distortion in the pre-stress anchor wall was verified by a comparison of the results of the anchor bolt axial force increment and the wall horizontal displacement increment obtained from the numerical simulation and the theoretical calculation, respectively. Various factors were analyzed using the FLAC3D calculation to ensure the change laws of the pre-stress anchor wall under blasting seismic wave.