土工织物补强软基的作用机理与整体稳定性分析

《规范》（GB50290-98）规定采用圆弧稳定性分析法计算加筋垫层路堤的抗深层滑动，所得到的最小稳定安全系数往往偏低，未能反映筋材所起的全部作用。经对土与土工织物相互作用的机理分析认为，对于具有中等拉伸强度和变形模量的织造土工织物，由于填土高度的增加使加筋垫层路堤与地基进入极限平衡状态的情况下，会表现出抗剪、抗拔和抗拉3种相互交叉的阻滑补强作用。通过3个现场足尺试验破坏堤段的比较，及对有1层土工织物加筋的试验堤段，按圆弧滑动法求出这3种阻滑机理下的最小抗滑稳定安全系数，说明了采用土工织物的阻滑补强作用效果；在具体工程中，会存在一种主要的阻滑作用机理。利用现场足尺破坏试验的实测资料提出，采用通过沉降最大值的堤基中心点的新的滑弧可使路堤的稳定分析计算更接近实际；在比较加1，2层和不加土工织物时，新滑弧比原滑弧求得的最小抗滑稳定安全系数有明显的增大。

Sliding resistance mechanism and whole stability analysis for reinforced soft foundation of embankment with geofabric

At present, the safety factors are improved little with circular failure analysis method stated in the criterion(Technical standard for applications of geosynthetics, GB50290-98) for preventing deep sliding of reinforced underlying layer of embankment with geofabric, which doesn’t agree with the actual effects. It shows that the circular arc analysis method doesn’t reflect the whole effects of reinforced geofabric. By analyzing interactional mechanism between soil and geofabric in detail, it considers that geofabric with middle tensile strength and modulus will exhibit the intercross sliding resistance mechanism of shearing resistance, of pulling-out resistance and of tension resistance, when embankment and its foundation achieve the state of limit equilibrium as the height of filling soil increases. By comparing the full scale test of embankment without reinforced underlying layer with the other two sections being provided with one or two reinforced underlying layers, the sliding resistance and reinforcement effects are revealed. Considering the above sliding resistance mechanism respectively, the minimum safety factors of the embankment with one reinforced underlying layer are worked out with circular failure analysis method. They also show the sliding resistance and reinforcement effects. It should be pointed out that in practice there is a leading sliding resistance mechanism. Further, making use of the data of the full scale test, a new circular sliding surface passing the point of maximum vertical settlement, which is the center point of interface between embankment and geofabric, is put forward. The computed safety factors of the embankment without or with one or two reinforced underlying layers are improved obviously with the new sliding surface and more closer to actual situation than the old one