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stress variation Model of Bond stress-Slip Relationship Between Steel Bar and Concrete

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China Ocean Engineering 1994年第1期9卷 79-86页

作者： Song Yupu Zhao Guofan Doctor and Professor, Dalian University of Technology, Dalian 116023 Professor, Dalian University of Technology, Dalian 116023

-Based on the experimental data, a stress variation model of the bond stress-slip relationship between steel bar and concrete is established. The characteristic of the model is that the boundary conditions are satisfied very well; the effects of the material properties, the concrete cover, the crack spacing and the distance from the cracked cross section are considered. Good agreement between measured and calculated bond stress-slip relationship is found. This model is useful for the study of the stiffness, deformation and crack width of reinforced concrete members, and for the nonlinear analysis of reinforced concrete structures by the finite element method.

关键词： bond stress slip bond stress-slip relationship stress variation reinforced concrete beams

Spatial and Temporal stress variations before and after the 2008 Wenchuan M_(w)7.9 Earthquake and its Implications:A Study based on Borehole stress Data

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Acta Geologica Sinica(English Edition) 2023年第1期97卷 226-242页

作者： MENG Wen LIN Weiren CHEN Qunce LI Yonghua Institute of Geophysics China Earthquake AdministrationBeijing 100081China Key Laboratory of Earthquake Source Physics China Earthquake AdministrationBeijing 100081China Key Laboratory of Active Tectonics and Geological Safety Ministry of Natural ResourcesInstitute of GeomechanicsChinese Academy of Geological SciencesBeijing 100081China Graduate School of Engineering Kyoto UniversityKyotoJapan

In situ stress measurement data was analyzed to estimate the temporal and spatial stress variations at shallow depths in the Longmenshan fault zone(LMSF),prior to and following the 2008 Wenchuan earthquake(WCEQ).Analysis of the stress field related to fault strength and behavior is useful for understanding geodynamic processes and conducting hazard *** shallow stress changes after the WCEQ show clear along-strike *** of stress orientation rotations have a negative correlation with the horizontal principal stress ratios and the WCEQ apparently reduced the magnitude difference between horizontal principal *** stress magnitudes and orientation distribution relative to the fault strike into account,we propose an intermediate-strength of LMSF,with a friction coefficient generally constrained between 0.35 and *** addition,high-pressure fluids in the fault zone reduce the effective normal stress and to a certain degree weaken the fault *** accumulated stress over a certain period following release of the WCEQ indicates the start of another earthquake *** changing crustal stress field makes the LMSF stable or slipping optimally during geodynamic *** segmentation feature of the shallow crustal stress field in the LMSF may imply a different tectonic loading and seismic release processes along the *** southwestern section to the epicenter of the WCEQ favors the occurrence of future earthquakes,as highμm in a state of critical failure was present in this area,which indicates that the Wenchuan and Lushan earthquakes did not release the accumulated stress to a sufficient extent there.

关键词： stress variation in situ stress measurement fault strength hazard assessment Longmenshan fault zone

Interaction between in situ stress states and tectonic faults:A comment

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International Journal of Minerals,Metallurgy and Materials 2023年第7期30卷 1227-1243页

作者： Peng Li Meifeng Cai Mostafa Gorjian Fenhua Ren Xun Xi Peitao Wang Beijing Key Laboratory of Urban Underground Space Engineering University of Science and Technology BeijingBeijing 100083China Key Laboratory of High-Efficient Mining and Safety of Metal Mines(Ministry of Education of China) University of Science and Technology BeijingBeijing 100083China Geological Engineering Department of EarthOcean and Atmospheric SciencesUniversity of British ColumbiaVancouverBCCanada

Understanding the in situ stress state is crucial in many engineering problems and earth science *** present article presents new insights into the interaction mechanism between the stress state and *** situ stresses can be influenced by various factors,one of the most important being the existence of faults.A fault could significantly affect the value and direction of the stress *** and magnitude changes in stresses exist adjacent to faults and stress jumps/discontinuities across the *** contrast,the change in the stress state may lead to the transformation of faulting type and potential fault *** fault reactivation assessment using characteristic parameters under the current stress environment provides a method to assess the slip tendency of *** correlation between in situ stresses and fault properties enhances the ability to predict the fault slip tendency via stress measurements,which can be used to further refine the assessment of the fault reactivation *** the future,stress measurements at greater depths and long-term continuous real-time stress monitoring near/on key parts of faults will be *** addition,much attention needs to be paid to distinguishing the genetic mechanisms of abnormal stress states and the type and scale of stress variations and exploring the mechanisms of pre-faulting anomaly and fault reactivation.

关键词： in situ stress state stress variation fault reactivation fault properties interaction mechanism

Controls of fault geometry and thermal stress on fault slip modes:Implications for permeability enhancement and injection-induced seismicity

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Petroleum Research 2021年第4期6卷 392-407页

作者： Dorcas S.Eyinla Michael A.Oladunjoye Department of Geology Pan African UniversityLife and Earth Sciences Institute(PAULESI)University of IbadanIbadanNigeria Department of Earth Sciences Adekunle Ajasin UniversityAkungba AkokoNigeria Department of Geology and Petroleum Geology School of GeosciencesUniversity of AberdeenAberdeenScotlandUnited Kingdom

Fluid pressurization within the fault zone generates increasing pore pressure and stress change which is liable to create shear and/or brittle fractures within the reservoir volumes and subsequently generating earthquakes of varying ***,we explored time-dependent fault weakening processes in the fault zone which are dependent on several factors,including the rate of cold-water injection,modes of injection(hydromechanical(HM)and thermo-hydro-mechanical(THM)interactions),and changing fault spatial configurations using data from Niger Delta *** variation in the stability of different fault models in withstanding stresses induced by HM and THM fluid interactions is *** permeability enhancement and the behaviour of slip event under isothermal and non-isothermal conditions revealed that stress and pore pressure perturbations have a first order control on the rate of fault dilation and *** is observed that the progressive cooling of the reservoir induced thermal stress which induced the timing of slip by unloading the fault to earlier seismic rupture in the non-isothermal case,and accelerates the magnitude of the fault reactivation and the accompanied induced *** to increased tendency of shear failure during injection,fracture opening through shear dilation is more enhanced in THM simulation as the fracture permeability is significantly higher than in *** effect becomes increasingly more dominant with intermediate fault angle and joint *** fault/joint configurations which were resistant to shear failure under isothermal injection had their frictional resistance broken by thermal *** results also indicate that there is higher pore pressure build-up in THM than in HM as the injection rate increases and reservoir temperature drops during cold injections..This study has demonstrated the importance of fully characterizing the fracture geometries and configurations of normal faulting regime in additio

关键词： Fault spatial arrangement Thermal stress Cold injection Injection-induced seismicity stress variation Slip delay