九寨黄龙机场填方高边坡动力稳定性分析

DYNAMIC STABILITY ANALYSIS OF HIGH FILL SLOPE OF JIUZHAI-HUANGLONG AIRFIELD

九寨黄龙机场工程土石方总量超过4?07 m3,填方边坡最大高度102 m。填方地基为砂层、卵石层、粉质粘土、砾岩及泥岩等组成的第四系河流沉积,结构复杂,物理力学特性变化大,场地附近有3条大的活动断裂,地震烈度为Ⅷ度。作为拟静力法计算结果的补充,用三维有限元与拟静力分析相结合的方法对填方高边坡动力稳定性进行研究。结果表明:在烈度为Ⅷ度的地震作用下,填体发生大规模整体滑移的可能性较小,但可能发生分离式破坏;受边界条件的控制,填体稳定性对来自岷江断裂方向的地震要比来自雪山断裂方向的地震更为敏感。

Jiuzhai-Huanglong airfield is located in high mountain-narrow valley area of the eastern fringe of Tibet plateau, about 450 km far from the northwest of Chengdu. The airfield is on the accumulated terrace of Min river and goes through five large scoured gutters. The maximum height of the fill slopes reaches 102 m and the total cubic meter of earth and stone exceeds 4×107 m3. The structure of the ground made of quaternary river sediments, which contain sand layers, pebble layers, sandy clay, conglomerate rock and mudrock, is complicated and its mechanical behavior varies greatly. There are three active faults near the airfield with earthquake intensity VI. A numerical method combining three dimensional finite element method with pseudostatic analysis is employed in the dynamic stability analysis of the high fill slope. The results reveal that under earthquake with intensity VIII, the possibility of integral slide of high fill slope is small, but the slope maybe fails disassembly. The fill slope stability is more sensitive to the earthquakes from Min river fault than that from Xueshan fault, which is controlled mainly by the boundary conditions of the fill body.