隧道开挖对黄土边坡的稳定性影响研究

Study on the stability of loess slope affected by tunnel excavation

随着我国基建事业的蓬勃发展,隧道的修建日益兴起,其涉及到的各类边坡的稳定性是决定工程质量的关键。基于西部地区黄土地质条件,通过FLAC3D软件建立了隧道开挖时黄土边坡的数值模型,系统研究了隧道开挖时不同坡角黄土边坡的变形破坏形态及应变分布特征。结果表明:(1)随着坡角的增大,隧道逐渐开挖时,黄土边坡经历了裂隙产生、裂隙发育和裂隙贯穿失稳而形成滑坡破坏的过程;(2)坡角为30°时,坡肩内部剪切应变增量值增大,有形成滑移面的趋势,当坡角为60°时,在隧道采动影响下,形成中点圆圆弧滑移面,导致滑坡失稳;(3)有限元软件FLAC3D与整体圆弧滑动法计算的黄土边坡稳定性结果基本一致。

With the vigorous development of China＇s infrastructure construction and the emerging construction of tunnel, various slope stability is critical in determining the quality of engineering. Based on the loess geologic conditions of the western region, numerical model of loess slope affected by tunnel excavation was established by the finite element software FLAC3D. The deformation and failure mode of the loess slope with different slope angles during the excavation of the tunnel and the distribution characteristics of the strain were studied systematically. The results show that ： （ 1 ） with the increase of slope angle, gradual tunnel excavation, loess slope experi- enced the process of crack formation, crack growth and the instability of the forming of landslide failure ; （2） when the slope angle is 30 degrees, the internal shear strain increment of the slope is increased, and there is a tendency to form the slip surface. When the slope angle is 60 degrees, it is affected by the influence of the tunnel mining, the middle point round arc slip surface is formed, which leads to the instability of the landslide;（3）the finite element software FLAC3D and the overall circular sliding method to calculate the loess slope stability resuhs are basically identical.