西南某山区机场高填方边坡稳定性研究

Stability of High Fill Slope of an Airport in Southwest Mountainous Area

以西南某机场高填方边坡为例,研究顺坡填筑砂泥岩碎块石土高填方边坡工程的稳定性。通过选取试验段场地进行大型直剪试验获得岩土体抗剪强度指标,用有限元强度折减法模拟分析高填方边坡变形失稳机制。结果表明:粉质黏土层作为高填方边坡地基的软弱夹层,若不处理将会显著降低高填方边坡的稳定性;随着砂泥岩碎块石土填料中细粒物质的逐渐下渗,在填筑体下部与稳定基岩之间会形成具有一定厚度的滞水层,其抗剪强度明显低于填筑体;通过基底开挖台阶的方法可以改变滞水层在滑面上的分布,随着开挖台阶高度的增大,边坡潜在滑面通过滞水层的范围减小,边坡稳定性系数增大;选取恰当的坡型可降低边坡整体失稳的可能性。

The stability of high fill slope which filled with sand-shale gravelly soil was studied based on a practical case of an airport high fill slope in southwest China. Rock and soil mass shear strength indexes were obtained through large direct shear strength tests in the field of the test section. At the same time, the deformation instability mechanism was simulated by strength reduction FEM. The result indicates that the silty clay layer is the weak interlayer of high fill slope foundation, and it will significantly reduce the stability of the high fill slope without treatment. Along with the fine grain material of sand- shale gravelly soil infiltration, the aquitard is formed with certain thickness between filling-up soil and stable basement, and the shear strength of this layer is obviously lower than the filllng-up soil. The distribution of the aquitard on slippery surface can be changed by setting steps in basement excavation. The range of slope slippery surface through the aquitard decreases with the increase of steps height, and the slope stability coefficient increases. Possibility of slope global instability can be reduced by selecting appropriate slope shape.