坡面角度对岩质边坡加速度高程放大效应的影响

The Influence of Slope Angle on the Elevation Amplification Effect of Rock Slope Acceleration

基于现场调查、振动台试验及理论计算等结果,由宏观现象定性的分析到理论求解的定量计算,全面、系统地研究坡面角度对岩质高陡边坡的加速度高程放大效应的影响。现场调查结果表明,边坡的失稳破坏主要发生在45°及以上的斜坡,从宏观现象上间接说明了随着坡面角度的增大,边坡的加速度放大效应会逐渐增强;振动台试验和理论计算结果从半定量和定量的角度揭示随着坡面角度的增大,临空面方向、竖直方向峰值加速度的高程放大效应逐渐增强,而在增强的过程中同时存在突然增大的拐点45°和渐趋平缓的拐点50°,即在45°以下加速度放大效应的增长较为缓慢,在45°-50°之间突然增大,在50°以上增长又逐渐变缓,这充分解释了＂滑坡灾害主要发生在45°以上的斜坡＂这一汶川地震震害现象。边坡走向方向的峰值加速度高程放大效应基本上不随坡面角度的增大而变化,其台阶也相对较为平缓。

A large-scale shaking table model test of a slope with a scale of 1：10was introduced.The model slope was composed of soil with a height of 1.8m,length of 4.4m,and width of 4.4m and included four slope angles of 30°,45°,50°,and 60°.The materials of the model test were blanc fixe,river sand,gypsum,clay,and water in various ratios.A series of tests was performed with various input seismic wave types,amplitudes,and frequencies.On the basis of field investigation results,shaking table test results,and theoretical analysis results,the influence of slope angle on the elevation amplification effect of rock slope acceleration was discussed.The results indicate that the amplifications of peak accelerations gradually increased with increases in slope angles.In addition,two inflection points were noted at slope angles of 45°and 50°,respectively,which suggests landslide hazards mainly occur on slopes with angles greater than 45°.Moreover,the ampliFig.1 The number of landslides vs slope gradientfication along the slope strike direction was essentially consistent,and the step was smooth.