基于X射线断层扫描预测岩石单轴抗压强度

Prediction on uniaxial compression strength of rocks with X-ray computed tomography

岩石单轴抗压强度是地下工程岩体开挖及稳定性分析的重要物理参数,准确快速确定岩石强度对指导工程岩体高效开挖具有现实性和必要性。考虑如何采用X射线断层扫描技术获得岩石单轴抗压强度,开展5组泥岩样的CT断层扫描,识别和提取CT序列图像中岩石不同密度物质的体数据特征,建立特征区域CT累加值和峰值强度的量化关系,提出基于X射线CT图像预测岩石单轴抗压强度的数学方法。研究表明:泥岩基质成分的CT累加值范围为1760~2560 HU,强度占比为0.94~0.96;岩石基质成分的CT累加值与峰值应力(σc)呈二阶函数关系;CT图像预测岩石强度的核心关键在于提取序列图像中特征区域的CT累加值,可进一步反演计算得出相应的峰值应力;成分单一、均质性和完整性较好的岩石试件,CT图像预测强度可获得相对较为精确的结果。

Uniaxial compression stress(UCS)is the important parameters of rock mass excavation and its stability analyzing in the underground engineering.UCS determination of rocks is really necessary to provide some scientific guidance for engineering excavation.This study focuses on how to get UCS of rocks with X-ray computed tomography.Five mudstone specimens for example are scanned with using of medical X-ray CT device.Then,volume data characteristics of different density materials have been identified and extracted from CT series images of rocks.UCS of rocks is quantitated with cumulative CT numbers of different density materials in X-ray series images.A new method which is called X-ray CT images prediction(X-CTIP)is proposed for determining UCS of rocks.The results show that cumulative CT numbers of mudstone composition range from 1760 to 2560 HU,which determining strength ratio is 0.94 to 0.96 and is also quadratic with UCS.Hence,the key task for predicting UCS of rocks extracted the CT cumulative value from X-ray sequence images and then re-calculated the corresponding UCS.The X-CTIP method can be used as determining relatively accurate UCS of rocks with a single composition,better homogeneity and integrity.