开挖对顺向岩质高边坡稳定性影响及锚索加固效果分析

顺向岩质高边坡的稳定性通常较差，在工程上格外受到重视，利用锚索锚固是较为理想的加固方案。利用Sarma法对厦沙高速公路某段石英片岩顺向岩质高边坡在施加锚索和不加锚索两种工况下的应力特征和边坡稳定性系数进行对比分析。结果表明:不加锚索时，各条块底面正压力随开挖过程呈降低趋势，越靠近边坡顶部，各条块底面正压力受到开挖卸荷的影响越大，降低趋势越明显；条块底面正压力的降低使边坡抗滑力减小，当减小幅度较大时，边坡稳定性会受到明显影响，整个开挖过程中边坡整体稳定性系数呈下降趋势，最低为1.243；施加锚索能够增大条块底面正压力，提高条块底面的抗滑力，有效降低条块底面受到的剪切力，限制上部条块的滑动趋势，减小其对下部条块的挤压和相对错动，且随着开挖的加深，这种效应表现得越明显；对某个条块而言，施加锚索可以提高底面抗剪强度，降低底面和侧面剪切力、条块下滑力，从而提高边坡稳定性；施加锚索后边坡稳定性系数提高到1.630。综上所述，边坡开挖对于顺向岩质高边坡稳定性影响很大，而施加锚索加固可以显著提高边坡稳定性，达到加固边坡的目的。

Analysis of the Influence of Excavation on Stability of High Lithological Bedding Slope and the Reinforcement Effect of Anchor Cable

The stability of high lithological bedding slope is usually poor, and it pays extra attention in the engineering practice, and anchor cable is an ideal reinforcement scheme. The Sarma method was applied to compare the stress characteristics and the slope stability coefficient of quartz schists in high lithological bedding slope of Xia-Sha expressway with and without anchor cable. The results show that the positive pressure of each slice bottom decreases with the excavation process without anchor cable, and the closer to the top of the slope, the greater the positive pressure of each slice is subjected to excavation unloading, and the more obvious the decreasing trend; the decrease of the positive pressure at the slice bottom decreases the sliding resistance force of the slope, and when the reduction is large, the slope stability will be significantly affected, and the stability coefficient of the slope decreases with a minimum of 1.243 during the whole excavation process; the positive pressure at the slice bottom increases with anchor cable, the sliding resistance force at the slice bottom can be improved, and the shear stress at the slice bottom also decreases, the sliding trend of the slice top can be limited, the extrusion and relative dislocation of the slice lower part are reduced, these above phenomena appear more obviously with the deepening of the excavation; furthermore, when the shear strength at the slice bottom is improved with anchor cable, the shear stresses of the slice bottom and side are reduced, and the sliding force of the slice is reduced, the purpose of slope reinforcement is achieved with the stability coefficient of 1.630. In conclusion, the slope excavation has great influence on the stability of the high lithological bedding slope, and the reinforcement with anchoring measures can significantly improve the stability of the slope and achieve the purpose of slope reinforcement.