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岩爆等级预判是进行岩爆灾害预警的重要基础,而岩爆本身的复杂性给岩爆预判带来了很大困难,为实现岩爆等级快速、准确地预判,采用声发射测试技术获取不同方向(纵向、斜向和横向)岩石的标准试样(直径为50mm、高度为100mm)在室内单轴压缩加载过程中的声发射特征,基于不同方向试件主破裂前的累积声发射能量Eq与最终破裂后的累积声发射能量E之比分别提出相应的岩爆等级预判新方法,并将预判结果与实际岩爆等级、传统方法的岩爆预判结果进行了对比。结果表明:基于不同方向试件Eq/E值的岩爆等级预判结果准确率均达到80%,与实际岩爆等级吻合性较好;与传统岩爆预判方法相比,基于Eq/E值的岩爆等级预判结果更为可靠;使用不同方向试件Eq/E值进行岩爆等级预判时,预判结果的准确率从高到低依次为纵向、斜向和横向。研究结果对于岩爆灾害防治具有一定的参考价值。 相似文献
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单轴压缩条件下花岗岩中不同细观组分的运动过程对花岗岩变形破坏过程分析具有重要意义,可以使用视频图像处理技术进行研究。根据花岗岩试件室内常规单轴压缩试验时摄取的试验视频,在提取单帧图像、进行灰度化和二值化处理基础上,得到试样中石英、长石、黑云母的实际分布,用Fourier变换指数评价这些细观组分的形状特征及其随时间的变化过程,使用粒子图像测速技术得到不同时刻、不同细观组分的位移情况,研究细观组分的运动方向、破坏顺序及其与岩石变形破坏过程的关系。结果表明,Fourier变换指数可以用于定量评价花岗岩细观组分的形状特征和细观组分形状的改变过程;在单轴受压过程中,不同细观组分发生明显变形的先后顺序是黑云母、长石、石英;细观组分的运动方向主要是垂直于加荷方向。本文研究成果对于分析岩石变形破坏机理具有一定的参考价值。 相似文献
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使用层次聚类(HC)、模糊C-均值聚类(FCM)、学习矢量量化(LVQ)、贝叶斯判别方法进行了黏性土层位的聚类分析与判别分析.土样选自上海某工程的26个样本,每一样本考虑10个常规土工试验指标.研究表明,使用FCM时,如果所选变量超过3个,误判率大约为19.2%;使用HC时,如果变量选为10个、类间距离采用类平均法、样品距离不使用海明距离,误判率也为19.2%左右;选择全部10个变量、使用LVQ进行网络训练与预测时,误判率大约为10.4%;使用贝叶斯判别方法对土样进行判别时,已有土样交叉验证的误判率为5.2%左右,新土样的误判率为14.2%左右.数据输入输出和分析判别过程全部使用作者编制的应用程序完成.作者提出的黏性土层位的聚类和判别分析方法,对土样鉴别具有一定的参考价值,可为土的类型确定和性质评判提供许多有用的信息. 相似文献
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The particle image velocimetry (PIV) method was used to investigate the full-field displacements and strains of the limestone
specimen under external loads from the video images captured during the laboratory tests. The original colorful video images
and experimental data were obtained from the uniaxial compression test of a limestone. To eliminate perspective errors and
lens distortion, the camera was placed normal to the rock specimen exposure. After converted into a readable format of frame
images, these videos were transformed into the responding grayscale images, and the frame images were then extracted. The
full-field displacement field was obtained by using the PIV technique, and interpolated in the sub-pixel locations. The displacement
was measured in the plane of the image and inferred from two consecutive images. The local displacement vectors were calculated
for small sub-windows of the images by means of cross-correlation. The video images were interrogated in a multi-pass way,
starting off with 64×64 images, ending with 16×16 images after 6 iterations, and using 75% overlap of the sub-windows. In
order to remove spurious vectors, the displacements were filtered using four filters: signal-to-noise ratio filter, peak height
filter, global filter and local filter. The cubic interpolation was utilized if the displacements without a number were encountered.
The full-field strain was then obtained using the local least square method from the discrete displacements. The strain change
with time at different locations was also investigated. It is found that the normal strains are dependant on the locations
and the crack distributions. Between 1.0 and 5.0 s prior to the specimen failure, normal strains increase rapidly at many
locations, while a stable status appears at some locations. When the specimen is in a failure status, a large rotation occurs
and it increases in the inverse direction. The strain concentration bands do not completely develop into the large cracks,
and meso-cracks are not visible in some bands. The techniques presented here may improve the traditional measurement of the
strain field, and may provide a lot of valuable information in investigating the deformation/failure mechanism of rock materials. 相似文献
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为了研究岩石表面变形破坏过程的变化特征,设计了一个可视化应用程序.该应用程序以岩石常规力学性质试验视频作为研究对象,包括静态图像处理界面和视频图像处理界面.静态图像处理界面由图像类型转换、图像边缘检测、图像形态学处理、图像滤波处理4个模块组成.视频处理界面则提供试验视频帧数、历时、帧图像大小和维数等基本信息.通过在可视化界面上进行所需参数设置实现了单帧图像特征纹理参数计算和岩石试样表面位移场的计算.本文还以两个示例说明了使用该应用程序进行岩石材料变形破坏过程分析的方法.本文成果对分析岩石材料变形特点和破坏机制具有一定的参考价值. 相似文献
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以大尺寸耐候试验箱的彩钢板饰面层外墙外保温系统为试验对象,提出了一套完整的外保温系统构造层温度场实测方案,测得高温-淋雨循环下彩钢板饰面层外墙外保温系统各构造层温度数据;根据实测结果对比分析了分别以泡沫玻璃、硬泡聚氨酯和泡沫混凝土作为保温材料的外墙外保温系统构造层温度场分布特征、延迟时间和衰减系数.结果表明,彩钢板饰面层外墙外保温系统饰面层、保温层的温度变化特征与箱内气温一致,界面层受箱内气温影响较小,变化比较平缓;窗口位置温度波动幅度较墙体中心位置大;硬泡聚氨酯保温隔热效果优于泡沫玻璃和泡沫混凝土.各系统墙体的温度波动在各构造层中的延迟时间相同,保温层使得墙体温度场衰减显著. 相似文献