甘肃兰州某黄土建筑高边坡失稳原因及补强治理方案

Instability of a high loess slope in Lanzhou city of Jiangsu province and suggestion for its reinforcement

通过对兰州市某黄土建筑高边坡现场变形及工程地质条件系统调查的基础上,采用有限元软件Plaxis对目前开挖状态下坡体应力应变状态进行了数值分析,并对该边坡实施了地表及支护结构物表面位移监测。在以上基础上分析了该边坡失稳的原因,并针对该边坡的治理难度及特点,提出了合理治理方案并得出以下结论:(1)位移监测结果表明,目前变形以水平位移为主,沉降较小。22个监测点中,14个监测点累计水平位移超过20 mm,17个监测点日平均水平位移速率大于0.2 mm/d。累计水平位移至已超过规范警戒值,及时实施坡顶应急搬迁及坡脚停止施工的措施、坡顶建筑物拆迁后,位移速率呈明显降低趋势。(2)有限元分析表明,原支护桩基埋置深度较浅,未进入卵石层,桩锚固段过短,且锚杆没有穿过滑裂面,无法提供锚固力,支护桩产生了倾倒式变形,这与位移监测以水平变形为主是吻合的。(3)基于强腰固脚的理念,提出了坡体上部减载,中部锚固,下部抗滑桩支挡的合理治理方案;(4)针对该超限边坡长期稳定监测,提出施工两年后监测到期,采取延长监测、减少次数、重点监控的建议。

Through surveying the deformation and the engineering geological conditions of the loess high slope in Lanzhou. To take the finite element software Plaxis, By adopting the method of numerical simulation analysis of the current state of the excavation slope body stress and strain state, and take the implementation of displacement monitoring. On the basis of above analysis the causes of the slope instability. Against the difficulty of governance and characteristics of slope, this paper puts forward a reasonable management plan. （1） the displacement monitoring results shows the deformation is given priority to with horizontal displacement, subsidence is smaller 22 monitoring points, 14 cumulative horizontal displacement monitoring points more than 20 mm, daily average of 17 monitoring displacement rate is greater than 0. 2 mm/d. Cumulative horizontal displacement to more than standard value, and timely implementation of top emergency relocation and slope foot to stop construction of the measures, slope after building demolition, displacement rate showed a trend of decrease. （2） The finite element analysis shows the original supporting pile foundation embedment depth is shallow, not into the pebble bed, pile anchorage segment are too short, and no through the critical slip surface bolt, cannot provide the anchoring force, the dumping Of supporting pile type deformation, this is given priority to with horizontal deformation and displacement monitoring are identical. （3） Based on the concept of strong waist GuJiao, this paper puts forward that the upper slope lightening, central anchor, the lower of anti-slide pile retaining reasonable management plan. （4） For the overrun slope stability monitoring, it is suggested that after two years of monitoring expires, to extend the monitoring, reduce frequency, monitor and monitoring the new idea.