深部地下空区探测环境极其复杂,往往只能获取有限的探测数据点,常规的拟合方法只能得到较为粗糙的轮廓形态。鉴于此,结合孔内超声扫描技术,开展了空区立体轮廓确定的方法研究。首先,提出了针对超声扫描数据的预处理方法,判断有效数据点,并平滑处理非有效探测点,实现超声数据的有效筛选。其次,引入二次Bezier曲线,并提出了适用于空区水平断面拟合特点的曲线拟合方法,使Bezier曲线能够通过每一个有效探测点,实现空区轮廓的高精度拟合;水平断面轮廓拟合之后,叠加深度信息,采用线性插值完成空区轮廓的纵向插值拟合,实现空区的立体轮廓确定,并通过MatLab软件进行数据的计算和图像生成。最后,通过具体数据进行分析,并与其他拟合方法进行对比。结果表明:①孔内超声扫描系统能够为空区建模提供有效数据;②改进的Bezier曲线能够适用于空区水平断面轮廓的拟合;③基于超声扫描的空区轮廓拟合方法具有可行性和准确性。研究成果可为解决地下空区立体轮廓的绘制和地下深部的空区探测提供参考。

Due to the extremely complex detection environment of empty area in deep underground engineering, the detection data is often limited, thus we can only obtain rough contours by conventional fitting method. In view of this, we propose a method for determining the 3-D profile of empty area by using borehole ultrasonic scanning technique. Firstly we present a preprocessing method for the effective screening of ultrasound scanning data by determining valid data points and smoothing non-effective detection points; secondly, by introducing the second-order Bezier curve, we present a curve fitting method which could cover every single effective detection point, favorable for the fitting characteristics of horizontal sections of the empty area; after horizontal contour fitting, we accomplishedvertical fitting by linear interpolation based on depth information, and acquired computation result and 3-D images by MatLab software. Subsequently we compared the results with those obtained from other fitting methods, and the comparison suggest that: 1) the borehole ultrasonic scanning system is able to provide effective data for the modeling of empty area; 2) the improved Bezier curve is feasible and suitable for the fitting of empty area profile; 3) the presented contour fitting method based on ultrasound scanning is proved feasible and accurate.