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Mechanism of zonal disintegration phenomenon in enclosing rock mass around deep tunnels

Journal of Central South University 2009年第2期16卷 303-311页

作者：吴昊郭志昆方秦张亚栋柳锦春 Engineering Institute of Engineering Corps PLA University of Science and Technology

In order to study the mechanism of the zonal disintegration phenomenon(ZDP),both experimental and theoretical investigations were carried ***,based on the similarity law,gypsum was chosen as equivalent material to simulate the deep rock mass,the excavation of deep tunnel was modeled by drilling a hole in the gypsum models,two circular cracked zones were measured in the model,and ZDP in the enclosing rock mass around deep tunnel was simulated in 3D gypsum model ***, based on the elasto-plastic analysis of the stressed-strained state of the surrounding rock mass with the improved Hoek-Brown strength criterion and the bilinear constitutive model,the maximum stress zone occurred in vicinity of the elastic-plastic interface due to the excavation of the deep tunnel,rock material in maximum stress zone is in the approximate uniaxial loading state owing to the larger tangential force and smaller radial force,the mechanism of ZDP was explained,which lay in the creep instability failure of rock mass due to the development of plastic zone and transfer of the maximum stress zone within the rock ***,the analytical critical depth for the occurrence of ZDP was obtained,which depended on the mechanical indices and stress concentration coefficient of rock mass.

关键词： zonal disintegration phenomenon (ZDP) block-hierarchical structure deep tunnel creep instability stress concentration coefficient

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RESEARCH OF A HIGH EFFICIENCY SLIDING SCREW DRIVER

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Chinese Journal of Mechanical Engineering 2004年第3期17卷 420-422页

作者： HuXiaowei LuHuailiang HuangShuhuai StateKeyLabofMouldandDieTechnology HuazhongUniversityofScienceandTechnologyWuhan430074，China

A high efficiency sliding screw driver is introduced. It can improve drivingefficiency obviously. As the material strength of the nut in this structure is low and the nut isthe most dangerous part, so it is important to master the structure's characters of deformation andstress. The deformation and stress of this structure are researched by finite element method(FEM),and the changing law of stress concentration coefficient of the structure is gained. So the exactstress of nut teeth with highest load can be calculated directly based on this result.

关键词： Sliding screw driver FEM stress concentration coefficient

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A Model for the Determination of Semi-Circular Spot Corrosion Damage and Residual Strength in Oil Pipes

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Fluid Dynamics & Materials Processing 2023年第6期19卷 1709-1720页

作者： Hongtao Liu Maoxian Xiong Bo Zhang Junfeng Xie Jinrui Deng MifengZhao Ruijing Jiang Yushan Zheng Research Institute of Oil and Gas Engineering Tarim Oilfield Company PetroChinaKorla841000China CNPC Research Institute of Safety and Environment Technology Beijing102206China

Pitting corrosion often occurs due to the presence of various corrosive substances,such as CO_(2) and H_(2)S,in the pipe service *** a result of this process,the residual strength of oil pipes is reduced and this can compromise the integrity of the entire pipe *** the present work,a model is introduced on the basis of the API579 standard to determine the so-called stress concentration *** model accounts for pitting corrosion shapes such as shallow semi-circles,semi-circles,and deep *** relationship between the corrosion pit depth and opening diameter and the residual strength of the oil casing is *** results show that the influence of the pit opening diameter on the stress concentration coefficient is smaller than that of the pit *** a constant pit opening diameter,the coefficient increases gradually with increasing the pit *** compressive strength and internal pressure strength of the carbon steel oil casing decrease *** the depth of the corrosion pit is relatively small,the growth of the coefficient is slower;when the depth of the corrosion pit increases to a certain value,the increase in stress concentration coefficient becomes obvious.

关键词： Pitting corrosion residual strength stress concentration coefficient

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Zonal disintegration phenomenon in rock mass surrounding deep tunnels

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Journal of China University of Mining and Technology 2008年第2期18卷 187-193页

作者： WU Hao FANG Qin GUO Zhi-kun Engineering Institute of Engineering Corps PLA University of Science and Technology Nanjing Jiangsu 210007 China

Zonal disintegration is a typical static phenomenon of deep rock masses. It has been defined as alternating regions of fractured and relatively intact rock mass that appear around or in front of the working stope during excavation of a deep tunnel. Zonal disintegration phenomenon was successfully demonstrated in the laboratory with 3D tests on analogous gypsum models, two circular cracked zones were observed in the test. The linear Mohr-Coulomb yield criterion was used with a constitutive model that showed linear softening and ideal residual plastic to analyze the elasto-plastic field of the enclosing rock mass around a deep tunnel. The results show that tunneling causes a maximum stress zone to appear between an elastic and plastic zone in the surrounding rock. The zonal disintegration phenomenon is analyzed by considering the stress-strain state of the rock mass in the vicinity of the maximum stress zone. Creep instability failure of the rock due to the development of the plastic zone, and transfer of the maximum stress zone into the rock mass, are the cause of zonal disintegration. An analytical criterion for the critical depth at which zonal disintegration can occur is derived. This depth depends mainly on the character and stress concentration coefficient of the rock mass.

关键词： block-hierarchical structure zonal disintegration phenomenon enclosing rock mass around deep tunnel equivalent material stress concentration coefficient

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