基于离心模型试验与数值计算的超高陡加筋土填方边坡稳定性分析

Stability analysis of ultra-high-steep reinforced soil-filled slopes based on centrifugal model tests and numerical calculation

山区机场建设中会出现超高陡(高度达百米且填方坡比陡于1︰1)的加筋土填方边坡方案,针对这类填方边坡稳定性方面的研究较少。以云南某机场的超高陡加筋土填方边坡方案为例,通过大型土工离心模型试验及数值计算开展天然工况下这类加筋土填方边坡稳定性的研究,获得的主要成果:①边坡变形破坏以填方土体局部开裂、面板鼓胀和抗滑桩略微外倾为主,桩顶位移未超过设计允许偏移量;②边坡顶部以沉降为主,坡口沉降量最大,边坡中下部(基础面地形陡变及筋带变短的部位)兼有沉降和少量的侧向水平位移,坡体变形满足规范要求;③填方体内的土压力较小,坡体中下部土压力最大;筋带的单元轴力基本满足要求,仅基础界面地形陡变及下部筋带变短部位的少量筋带(数量少于4%)的轴力超过了其设计值。研究表明,这类超高陡加筋土填方边坡整体稳定性较好。但由于山区机场填方体呈上宽下窄的倒三角形,坡体中下部基础面地形陡变及筋带变短部位存在局部安全隐患,后续应优化方案,进一步增强边坡中下部局部稳定及加筋体内部稳定。相关成果能为山区机场超高陡加筋土填方边坡整体稳定性及后续研究提供参考,也可为类似离心试验提供借鉴。

In airport construction in mountainous areas, there is an ultra-high-steep(100-m slope ratio less than 1:1) reinforced soil-filled slope scheme, but there are few studies on the stability of this kind of slope. Taking the ultra-high-steep reinforced soil-filled slope scheme of an airport in Yunnan Province of China as an example, through the large-scale geotechnical centrifugal model tests and numerical calculation, the stability of the reinforced soil-filled slope under natural conditions is studied. The main results are as follows:(1) The deformation and failure of the slope include local cracking of filled soil, panel bulging and slight extroversion of piles, and the displacement of pile top does not exceed the allowable design deviation.(2)The displacement of the slope at the top is mainly subsidence, with the maximum subsidence at the mouth, and there are settlement and lateral horizontal displacement in the lower and middle parts of the slope at the interface between the reinforcement and the foundation at the steep terrain. The deformation of the slope meets the requirements of the specification.(3) The soil pressure inside the filled slope is lower, and that in the middle part of the slope is the greatest. The axial force basically meets the design requirements, while that of a small number of reinforcement bands at the interface between the reinforcement and the foundation exceeds the design value(less than 4%). The study shows that the overall stability of the ultra-high-steep reinforced soil-filled slope is better.However, the filled soil in the mountainous airport is an inverted triangle terrain, and there exist local hidden dangers in the middle and lower parts of the slope(where the terrain of foundation surface changes steeply and the reinforcement band shortens). Subsequently the schemes should be optimized so as to further improve the local stability of the slope and the internal stability of the reinforcement soil. The relevant achievement may provide reference for the stability analysis of ultra-high-steep reinforced soil slope of mountainous airports and other similar centrifugal model tests.