检索结果-南通市图书馆

Determining rock crack stress thresholds using ultrasonic through-transmission measurements

International Journal of Coal Science & Technology 2024年第2期11卷 67-80页

作者： Jiangwan He mehdi serati Martin Veidt Arthur De Alwis School of Civil Engineering The University of QueenslandBrisbaneQLD 4072Australia School of Mechanical and Mining Engineering The University of QueenslandBrisbaneQLD 4072Australia

The crack initiation stress threshold is widely used in excavation industries as rock spalling strength when designing deep underground structures to avoid unwanted brittle *** various strain-based methods have been developed for the estimation of this critical design parameter,such methods are destructive and often requires subjective interpretations of the stress–strain curves,particularly in rocks with pre-existing microcracks or high *** study explore the applicability of non-destructive ultrasonic through-transmission methods for determining rock damage levels by assessing the changes in transmitted signal characteristics during *** change in velocity,amplitude,dominant frequency,and root-mean-square voltage are investigated with four different rock types including marble,sandstone,granite,and basalt under various stress *** suggest the rate of signal variations can be reliably used to estimate crack closure and crack initiation stress levels across the tested rocks before *** of the results between the conventional techniques and the new proposed methods based on ultrasonic monitoring are further discussed.

关键词： Ultrasonic Non-destructive testing Brittle rock Crack initiation Velocity Amplitude Frequency

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Failure characterization of fully grouted rock bolts under triaxial testing

引用

Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 778-789页

作者： Hadi Nourizadeh Ali Mirzaghorbanali mehdi serati Elamin Mutaz Kevin McDougall Naj Aziz Centre for Future Materials(CFM) School of EngineeringUniversity of Southern QueenslandToowoombaQLD4350Australia School of Engineering University of Southern QueenslandSpringfield CentralQLD4300Australia School of Civil Engineering University of QueenslandSt LuciaQLD4072Australia School of Surveying and Build Environment University of Southern QueenslandToowoombaQLD4350Australia School of Civil Mining&Environmental EngineeringUniversity of WollongongWollongongNSW2500Australia

Confining stresses serve as a pivotal determinant in shaping the behavior of grouted rock ***,prior investigations have oversimplified the three-dimensional stress state,primarily assuming hydrostatic stress *** these conditions,it is assumed that the intermediate principal stress(σ_(2))equals the minimum principal stress(σ_(3)).This assumption overlooks the potential variations in magnitudes of in situ stress conditions along all three directions near an underground opening where a rock bolt is *** this study,a series of push tests was meticulously conducted under triaxial *** tests involved applying non-uniform confining stresses(σ_(2)≠σ_(3))to cubic specimens,aiming to unveil the previously overlooked influence of intermediate principal stresses on the strength properties of rock *** results show that as the confining stresses increase from zero to higher levels,the pre-failure behavior changes from linear to nonlinear forms,resulting in an increase in initial stiffness from 2.08 kN/mm to 32.51 kN/*** load-displacement curves further illuminate distinct post-failure behavior at elevated levels of confining stresses,characterized by enhanced ***,the peak load capacity ranged from 27.9 kN to 46.5 kN as confining stresses advanced from σ_(2)=σ_(3)=0 to σ_(2)=20 MPa and σ_(3)=10 ***,the outcomes highlight an influence of confining stress on the lateral deformation of *** levels of confinement prompt overall dilation in lateral deformation,while higher confinements maintain a state of ***,diverse failure modes have been identified,intricately tied to the arrangement of confining *** confinements tend to induce a splitting mode of failure,whereas higher loads bring about a shift towards a pure interfacial shear-off and shear-crushed failure mechanism.

关键词： Rock bolts Bolt-grout interface Bond strength Push test Triaxial tests

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Cognitive correlates of neuroimaging abnormalities in the onset of schizophrenia: A case report

引用

World Journal of Psychiatry 2017年第2期7卷 128-132页

作者： Silvia Grassi Giulia Orsenigo Marta serati Elisabetta Caletti Alfredo Carlo Altamura Massimiliano Buoli Department of Psychiatry University of Milan Fondazione IRCCS Ospedale Maggiore Policlinico

Increasing evidence shows that cognitive impairment and brain abnormalities can appear early in the first episodes of schizophrenia, but it is currently debated how brain changes can correlate with clinical presentation of schizophrenic patients. Of note, this report describes the case of a young schizophrenic male presenting parietal magnetic resonance/positron emission tomography abnormalities and cognitive impairment, documented by specific neuropsychological tests. In our knowledge only few studies have investigated if neuropsychological abnormalities could be concomitant with both structural and functional neuroimaging. This case shows that impairment in specific cognitive domains is associated with structural/functional brain abnormalities in the corresponding brain areas(frontal and parietal lobes), supporting the hypothesis of disconnectivity, involving a failure to integrate anatomical and functional pathways. Future research would define the role of cognitive impairment and neurodegeneration in psychiatric nosography and, in particular, their role in the early phases of illness and long-term outcome of schizophrenic patients.

关键词： Positron emission tomography Magnetic resonance Schizophrenia Neuropsychology

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：