目标追踪算法在岩石表面变形测量中的实现与应用

Realization and application of target tracking algorithm in rock surface deformation monitoring

变形测量是岩石力学理论研究和工程实践的基础,数字图像相关算法在岩石变形测量中得到了广泛的应用,但在实际应用中存在位移云图边缘检测收敛性差、定量刻画参数少等问题。基于此,将目标追踪方法引入到岩石变形测量领域,提出基于目标追踪算法的岩石表面变形测量方法,该方法通过Harris角点检测,获取图像中关键特征点的位置,之后采用KLT算法计算出跟踪点在变形后图像中所对应的位置,从而确定岩石表面的全场位移。为验证算法的可靠性,开展室内岩石剪切试验,对比分析目标追踪算法和数字图像相关算法的试验结果。研究结果表明:目标追踪算法能够实现岩石表面的非接触位移测量,相比数字图像相关算法,精度和稳定性有一定提升。目标追踪算法解决了数字图像相关算法在岩石边缘处变形量计算不收敛、稳定性差等问题,真正实现了在可计算范围内全场位移量的拾取。提出利用信息熵来定量刻画岩石破坏过程变形场的演化特征,有助于更全面、更准确地分析岩石在各种复杂外载荷作用下的力学行为。所提出的一种新的岩石表面变形场测量方法,为可视化研究岩石表面变形演化规律及损伤特征提供有效的技术手段,同时也为岩土工程领域非接触变形测量提供一定借鉴。

Deformation measurement is the basis of rock mechanics theory research and engineering practice.Digital image correlation algorithm has been widely used in rock deformation measurement,but there are some problems in practical application,such as poor convergence of displacement cloud edge detection and few quantitative characterization parameters.Based on this,this paper introduces the target tracking method into the field of rock deformation measurement,and proposes a rock surface deformation measurement method based on target tracking algorithm.This method obtains the position of key feature points in the image through Harris corner detection,and then uses KLT algorithm to calculate the corresponding position of tracking points in the deformed image,so as to determine the whole field displacement of rock surface.In order to verify the reliability of the algorithm,indoor rock shear experiments are carried out,and the experimental results of target tracking algorithm and digital image correlation algorithm are compared and analyzed.The results show that the target tracking algorithm can realize the non-contact displacement measurement of rock surface,and the accuracy and stability are improved compared with the digital image correlation algorithm.The target tracking algorithm solves the problems of non convergence and poor stability of the digital image correlation algorithm in the calculation of deformation at the rock edge,and truly realizes the pickup of the whole field displacement within the calculable range.Using information entropy to quantitatively describe the evolution characteristics of rock deformation field in the process of failure is helpful to analyze the mechanical behavior of rock under various complex external loads more comprehensively and accurately.In this study,a new measurement method of rock surface deformation field is proposed,which not only provides an effective technical means for the visual study of rock surface deformation evolution law and damage characteristics,but also provides a certain reference for non-contact deformation measurement in the field of geotechnical engineering.