基于B型深孔测斜曲线的滑坡滑动面位置确定方法

Method for determining the position of landslide slip surface based on B-type inclinometer curve

在实际的深孔位移监测中,测斜曲线的突变特征是滑动面辨识的关键依据,对于“B”型测斜曲线通常是将曲线的鼓包凸起点作为滑动面的位置,但这种方法容易受到测点布置间隔和横纵坐标观测尺度的影响,存在滑面位置定义不清晰、数值不确定的问题。为了能够有效地克服这些缺点,提升测斜曲线滑动面辨识的准确度,基于“B”型测斜曲线变化特征,研究将滑坡抽象为由“滑动体”、“滑动区间”以及“不动体”三者组成的概化模型,并对滑坡运动过程中不同深度处土体的位移速率和加速度变化特点进行了深入分析。结果表明:土体位移速率沿深度方向会形成多道曲线簇,且不同曲线簇分别对应各滑面所在的滑动区间及非滑动区间。此外,将位移速率转化为加速度,则土体加速度曲线具有更加显著的分簇特征,能够为准确区分滑动体和不动体的区间范围提供重要依据。进一步地,提取监测期内加速度曲线分簇特征显著的当日土体加速度并绘制散点图,能够快速准确地确定坡体不同区间的深度范围。基于当日各滑面所在滑动区间内的加速度数据,运用三次样条插值法计算该区间内的位移加速度最大值,由于滑面处的土体加速度最大,则该值对应的土体深度可作为滑面位置的计算深度。研究方法能够更加精准地确定滑动面位置,并使滑面位置的确定可计算化,有效提升了深孔位移监测数据的利用程度和可靠度,具有较大的实用价值。

In the actual deep hole displacement monitoring,the mutation character of the inclinometer curve is the key basis for the identification of slip surface.For the B-type inclinometer curve,the bulge convex point of the curve is usually taken as the position of sliding surface.However,this method is easily affected by the arrangement interval of detection points and the coordinate-scale,which makes the position of the sliding surface unclear and the value uncertain.In order to overcome these shortcomings effectively and improve the accuracy on identification of sliding surface with inclinometer curve,the landslide in this study is simplified into a generalized model composed of sliding body,sliding interval and immovable body based on the variation characteristics of B-type inclinometer curve.And we also analyzed the characteristics of soil displacement rate and acceleration at different depths in the process of landslide movement.The results show that the soil displacement rate will form multiple curve clusters along the depth direction,and different curve clusters correspond to the sliding section of sliding surface and non-sliding section respectively.In addition,if the displacement rate is converted into acceleration,the soil acceleration curve has more obvious clustering characteristics which can provide an important basis for accurately distinguishing the interval range of sliding bodies and immovable bodies.Furthermore,this study extracts the soil acceleration of the day with significant clustering characteristics of acceleration curve during the monitoring period and draws a scatter plot,which can quickly and accurately determine the depth range of different sections of the slope.Based on the acceleration data in the sliding section of each sliding surface on that day,we use cubic spline interpolation to calculate the maximum acceleration in the section.Since the soil acceleration at sliding surface is the largest,the soil depth corresponding to this value can be used as the calculated depth of the sliding surface.The method proposed in this paper can determine the position of the sliding surface more accurately and make the determination of the sliding surface position computable.It effectively improves the utilization and reliability of monitoring data on deep displacement of borehole,and has great practical value.