黄土高边坡开挖过程的变形监测分析

Case Study of Deformation Behaviour of High Loess Slope in Excavation

以隧道出口路堑黄土边坡为例,分析黄土路堑开挖过程中边坡变形和边坡土钉应力随空间和时间的变化规律。测斜仪监测结果表明:边坡的水平位移随开挖深度的增加逐步增大,并在开挖后一段时间内出现最大值,呈时间滞后效应。在不同的开挖阶段,坡体不同部位开挖后的水平位移变化幅度不同:坡顶变形幅度最大,坡底居中,坡体中部最小;坡体开挖完成后,坡顶绝对水平位移量最大,坡脚最小,坡体中部居中。随开挖深度的增加,坡体不同部位测试土钉各测点应力明显增大;土钉最大应力出现位置由坡面逐渐迁移到坡内。说明坡体的变形范围随开挖深度的增加而扩大;且由土钉最大应力出现的位置可判定边坡潜在滑动面位置。

On the basis of the data obtained by using the inclinometer and soil nail stress meter,the deformation behaviour of the loess cut slope at the exit of a tunnel during the process of excavation was analyzed.The results indicate as follows： The horizontal displacement of the slope increases gradually with growing of the depth of excavation and reaches its maximum after a period of time of excavation;the magnitudes of the horizontal displacements vary with the parts of the slope in different stages of digging,being the maximum at the top,the minimum at the mid part of the slope body and the middle at the base;upon completion of excavation,the absolute horizontal displacement reaches the maximum at the crest,the minimum at the foot and the middle at the mid part of the slope body;along with increasing of the depth of excavation,the stresses at various measuring points of soil nails in various parts of the slope body increase obviously;the appearance location of the maximum axial stress of the soil nail migrates gradually from the surface of slope to the inside of slope.It is seen that the range of the deformation of the slope body expands with increasing of the cutting depth and the location of the potential slip surface of slope may be traced more accurately according to the location where the maximum axial stress of the soil nail occurs.