宁杭高速公路宜兴兰右山深路堑高边坡整体稳定性探讨

分析了宁杭高速公路宜兴兰右山深路堑工程地质特征、边坡稳定性影响因素及边坡变形破坏机理,并在此基础上指出:该段西侧高边坡一级台阶为泥岩,二级以上台阶为石英砂岩,边坡呈"上硬下软"双层结构;由于泥岩岩性特殊,具有浸水软化、膨胀、崩解、易风化等特征,在地下水诱因下,这种双层结构类型对边坡稳定性十分不利;为高速公路运营安全,宜采取主动防护措施,如坡面封闭隔水处理、预应力锚索、砂浆锚杆框架等防护方案,防止发生边坡深层破坏。

Discussion on Slope Stability of Yixing Lanyoushan Deep Chasm on Ning-Hang Freeway

Nanjing-Hangzhou freeway goes across Yixing Lanyoushan from north to south. The hill is low, which extends from east to west. The maximum depth of the west side chasm slope is 40 meters. The slope is designed as step-stairs. The height of every step-stair is 8 meters in this region. The compartments of the slope is rock mass. The main rock layer is Wutong group quartz sand stone of Devonian period, the double layer is mud stone. The rock mass strength is low. The rock layer′s dip angle is small, whose thickness changes from medium to large. The mud stone surface of western slope inclines to interior. The paper mainly analyses influence factors on deep chasm slope stability and breakage mechanism of slope distortion of Yixin Lanyoushan on Ning-Hang freeway. The paper points that the first step is mud-rock, the second step and the higher setps are quartz sand-rock in this section with high slope on right side,whose slope appears "rigid upward, soft downward". Because of the particularity of mud-rock which can soften, expand or collapse after being inundated, the two-layer structure type is disadvantageous to slope stability under the effect of ground water. In order to ensure normal operation of the freeway, some protective measures such as slope surface waterproof, prestressing force anchored cable and mortar anchored piles framework have been taken to prevent the slope from being deeply destroyed.