交通荷载下分离式路基边坡力学响应及变形特性

Mechanical Response and Deformation Characteristics of Separated Subgrade Slope under Traffic Load

为了分析交通荷载循环多次作用下分离式路基高边坡的受力变形情况,采用FLAC3D建立分离式路基边坡数值计算模型,从应力、位移等方面,分析不同坡高、坡角时边坡的力学响应及变形特性。研究结果表明:交通荷载下,坡高增加时,边坡坡脚处始终是应力集中区。随着坡高的增加,最小主应力、最大剪应力、XZ方向剪应力的应力集中区不断向边坡下侧路基及坡面“侵蚀”。随着时间推移,各监测点处X和Z方向的速度趋于稳定,速度的大小顺序与其最大位移相匹配。监测点1处速度时程曲线的双向振荡是由于两个行车道车辆荷载传播时间差引起。坡角30°时,监测点3速度的高位波动反映了破面中部的“鼓胀”。边坡上部X方向的位移具有一定倾角的“条带状”分布。坡脚处X方向位移趋于0,Z方向位移最大。Z方向位移是X方向位移的2~3倍,远大于X方向位移。坡高、坡角增加时,边坡上部X和Z方向位移均先增大后减小,在坡高15 m、坡角45°时位移最大。坡高20 m和坡角30°时,坡面中部位移最大。

The paper analyzes the stress and deformation characteristics of high embankment slopes in separate roadbeds under the action of repeated traffic load cycles.FLAC3DA is used to establish a numerical calculation model of separate roadbed embankment slopes,the mechanical response and deformation characteristics of which at different slope heights and angles were analyzed in terms of stress and displacement.The results indicate that under traffic loads,stress concentration always occurs at the toe of the slope as the slope height increases.With the increase in slope height,the stress concentration zones of minimum principal stress,maximum shear stress and shear stress in the XZ direction continuously“erode”towards the lower side of the slope and the slope surface.Over time,the velocities in the X and Z directions at each monitoring point tend to be stable,and the magnitude of velocities matches the order of its maximum displacement.The bi-directional oscillations in the velocity-time curve at monitoring point 1 are caused by the time difference in the propagation of the vehicle load between the two lanes.At a slope angle of 30°,the high-frequency fluctuations in velocity at monitoring point 3 reflect the“bulging”in the middle of the failure surface.The X-direction displacement in the upper part of the slope exhibits a“striped”distribution at a certain inclination angle.At the toe of the slope,the displacement in the X-direction goes to zero,while the displacement in the Z-direction is maximal,considerably greater(2 to 3 times)than that in the X direction.As the slope height and angle increase,the displacements both in the X-and Z-direction initially increase and then decrease,which reach the maximum at a slope height of 15 m and a slope angle of 45°.At 20 m and 30°,the maximum displacement occurs at the middle of the slope surface.