吉贾尔-帕坦喀喇昆仑公路沿线落石和边坡稳定性数值研究

在中巴经济走廊的重要通道喀喇昆仑公路（KKH）沿线,由于构造运动和降雨渗透对破碎岩石和边坡稳定性的不利作用,造成了大量落石和不稳定边坡。利用数值软件DIPS、GeoRock 2D和SLIDE对巴基斯坦北部吉贾尔-帕坦喀喇昆仑公路沿线的落石和边坡稳定性进行了数值研究;以喀喇昆仑公路沿线两个主要的易受落石影响的路段为例,研究落石和边坡的失稳机理。对4组节理进行的赤平投影分析表明：两处边坡断面均易发生平面破坏和楔形破坏。基于极限平衡理论,在静力条件下,边坡断面1的安全系数为0.917,处于不稳定状态,边坡断面2的安全系数为1.131,处于欠稳定状态;但在地震条件下,两处断面边坡的安全系数均小于1,处于不稳定状态。研究结果表明,边坡断面1和断面2的落石回弹高度分别为33 m和29 m。边坡断面1的落石速度在0.5~44 m/s,总动能达到1 135.099 kJ,而边坡断面2的落石具有0.5~40.901 m/s的速度和973.012 kJ的破坏能力。研究表明,KKH沿线的落石和滑坡具有极大的破坏潜力。

Numerical analysis of rockfall and slope stability along the Karakorum Highway in Jijal-Pattan

Along the Karakorum Highway (KKH), the key route for the China-Pakistan Economic Corridor, there are many rockfalls and unstable slopes, usually caused by tectonic movement and rainfall on the fractured rocks and slopes. This paper presents a numerical investigation of the rockfall and slope stability along the Karakorum Highway in Jijal-Pattan, Northern Pakistan using DIPS, GeoRock 2D and SLIDE, focusing on rockfall and slope stability along the KKH to develop countermeasures. Along the KKH, two major sections susceptible to rockfalls were selected to investigate the mechanism of rockfall and slope instability. The stereographic projection analysis following four sets of joints indicates that both sections are prone to plane failure and wedge failure. Based on the limit equilibrium theory, under static loading, the slope for Section 1 showed a stability coefficient of 0.917, representing its instability, and the slope in Section 2 has a stability coefficient of 1.131 depicting its slight stability. However, under the seismic condition, the stability coefficients of the slopes were lower than 1 for both sections, which indicates their instability. The results by GeoRock 2D reveal that in Section 1 the fallen rock mass attained the bounce height of 33 m, and in Section 2 it attained a bounce height of 29 m. The fallen rocks in Section 1 have the total kinetic energy of 1 135.099 kJ with a velocity ranging from 0.5 m/s to 44 m/s, while in Section 2 the fallen rocks have a velocity ranging from 0.5 m/s to 40.901 m/s with a damage capacity of 973.012 kJ. This study showed the rockfalls and landslides along the KKH have great damage potential.