基于数字散斑相关的土体剪切带自动识别方法与应用

Automatic identification method and application of shear band ofsoils based on DSCM

剪切带是土体局部化变形的典型形式,是控制土体稳定性的重要因素。为了自动、精确识别模型试验中剪切带,基于自行研制的数字散斑相关(digital speckle correlation method,DSCM)软件系统PhotoInfor,提出采用最小二乘曲线拟合的砂土剪切带识别方法,针对不同倾角下剪切带边界点的识别问题,设计一种基于最佳拟合线搜索的剪切带自动识别算法,给出基于边界点识别结果的剪切带厚度及剪切带内应变的简明计算方法。通过室内大型砂土剪切模型试验,验证该方法的有效性。研究结果表明,在剪切过程中剪切带呈现剪胀特点,剪切变形可分为缓慢增长和急速增长两个阶段,剪切带最终形成时的厚度在不同区域并不完全相同。研究成果可为岩土力学试验中识别与分析剪切变形模式提供一种简便高效的方法,对于研究土体变形特性和评判工程稳定性都具有重要意义。

Shear band is a typical form of localized deformation of soil and an important factor to control soil stability.For automatic and accurate identification of shear bands in model tests,a sand shear band identification method using least square curve fitting was proposed based on the self-developed digital speckle correlation method software system PhotoInfor.Aiming at the problem of identifying the boundary points of the shear band at different dip angles,an automatic identification algorithm of the shear band based on the search of the best fitting line was designed and implemented.A concise calculation method for the thickness of the shear band and the strain in the shear band based on the identification results of the boundary points was given.The validity of this method was verified in the laboratory large-scale sand shear model test.The results show that the shear band is characterized by dilatancy in the shear process,and the shear deformation can be divided into two stages,i.e.,slow growth and rapid growth.The thickness of the shear band when it finally forms is not completely the same in different regions.The research results can provide a simple and effective method for identifying and analyzing shear deformation patterns in geotechnical mechanics tests,which is of great significance for studying soil deformation characteristics and evaluating engineering stability.