高烈度区库岸填石路基边坡稳定性及沉降分析

Settlement and Stability Analysis of High Rock-fill Reservoir Bank Embankment in High Seismic Region

高填方填石路基边坡稳定性及沉降问题一直都是高速公路建设、施工面临的重要问题。文章以西部山区高速公路浸水高填石路基为研究对象,通过室内试验研究了不同压实度下填石材料的干重度、内摩擦角等物理力学参数,分析了不同压实度填石材料、库水位升降和地震作用对路基边坡稳定性和沉降影响。结果表明:天然工况和地震工况下,同一库水位条件下,边坡稳定系数随着压实度增大而增大;不同压实度条件下,边坡稳定系数随着库水位的变动都出现了先下降后上升的趋势;但地震工况下,压实度93%、94%的填石路基边坡稳定性不满足公路工程抗震规范要求;天然工况下,随着压实度的提高,路基的变形值逐渐降低,路基以垂直变形为主,有向临空面侧向挤出趋势;地震工况下,随着压实度的提高,路基的相对变形值逐渐降低,但位移量较天然工况明显增大,路基以水平向外变形为主,且相对位移量等值线与地层岩性交界面平行,可能会沿着路堤与基底的交界面发生破坏。

The stability and settlement of high rock-fill embankment are important problems in highway construction.In the paper the stability and settlement of high rock-fill embankment are studied which is under the conditions of immersion and with high-filled rock embankment.The physical and mechanical parameters such as dry weight and internal friction angle of rock-fill materials under different compaction degrees are studied through laboratory tests.The effects of rock-fill materials with different compaction degrees,reservoir water level rise and fall and earthquake action on the stability and settlement of embankment are analyzed.The findings are drawn as follows:under natural and seismic conditions,the slope stability coefficient increases with the increase of compaction degree at the same reservoir water level.Under different compaction conditions,the slope stability coefficient first decreases and then rises with the change of reservoir water level.However,under seismic conditions,the slope stability of rock-fill embankment with 93%and 94%compaction degree does not meet the requirements of specifications for seismic design of highway engineering.Under natural conditions,with the increase of compaction degree,the deformation value of embankment decreases gradually.The embankment settlement is mainly vertical deformation,and has lateral extrusion trend toward the surface.Under seismic condition,with the increase of compaction degree,the relative deformation value of embankment decreases gradually,but the displacement is obviously larger than that under natural condition.The embankment settlement is mainly horizontal and outward deformation,and the relative displacement contour is parallel to the interface of strata,which may destroy along the interface of embankment and foundation.