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Influence of stress and high temperature treatment on the permeability evolution behavior of sandstone

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Acta Mechanica Sinica 2019年第2期35卷 419-432页

作者： Peng Xu sheng-qi Yang State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil Engineering China University of Mining and Technology Xuzhou 221116 China

Permeability is an important property of rock in gas and oil exploration engineering, environment temperature and geo-stress have great influence on it. This paper aims to analyze the influence of thermal treatment on the permeability of sandstone under triaxial compression. Based on the gas seepage tests on a sandstone specimen after different thermal treatment temperatures with different gas pressures, hydrostatic stresses and deviatoric stresses, the thermal effect on physical property of sandstone is firstly analyzed. The results show that the mass of the sandstone specimen decreases with the increase of temperature, some spalling damage and tensile crack occur on the lateral surface of the specimen at 400℃. According to the seepage test results with various gas pressures, an exponential relationship has been found between the permeability coefficient and temperature. The permeability coefficient is approximately 100 times as large as the initial value when the temperature increases from 20℃ to 800℃. The permeability evolution of the heated sandstone under hydrostatic and deviatoric compression has also been analyzed. A simplified double pore texture model is proposed which can well describe the permeability evolution of sandstone under compression with hydrostatic stress and deviatoric stress, it can be helpful to estimate the permeability of thermal treated sandstone under elastic triaxial compression.

关键词： Sandstone Triaxial compression Permeability Thermal treatment Double pore texture model

Particle flow study on strength and meso-mechanism of Brazilian splitting test for jointed rock mass

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Acta Mechanica Sinica 2014年第4期30卷 547-558页

作者： sheng-qi Yang Yan-Hua Huang State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil EngineeringChina University of Mining and Technology

A discrete element method （DEM） called particle flow code （PFC2D） was used to construct a model for Brazilian disc splitting test in the present study. Based on the experimental results of intact Brazilian disc of rock-like material, a set of micro-parameters in PFC2D that reflected the macro-mechanical behavior of rock-like materials were obtained. And then PFC2D was used to simulate Brazilian splitting test for jointed rock mass specimens and specimen containing a central straight notch. The effect of joint angle and notch angle on the tensile strength and failure mode of jointed rock specimens was detailed analyzed. In order to reveal the meso-mechanical mechanism of crack coalescence, displacement trend lines were applied to analyze the displacement evolution during the crack initiation and propagation. The investigated conclusions can be described as follows. （1） The tensile strength of jointed rock mass disc specimen is dependent to the joint angle. As the joint angle increases, the tensile strength of jointed rock specimen takes on a nonlinear variance. （2） The tensile strength of jointed rock mass disc specimen containing a central straight notch distributes as a function of both joint angle and notch angle. （3） Three major failure modes, i.e., pure tensile failure, shear failure and mixed tension and shear failure mode are observed in jointed rock mass disc specimens under Brazilian test. （4） The notch angle roles on crack initiation and and joint angle play important propagation characteristics of jointed rock mass disc specimen containing a central straight notch under Brazilian test.

关键词： Jointed rock mass Brazilian splitting test. Ten-sile strength· Failure mode PFC2D

Mn、Zn、Sn掺杂CsPbI_(3)的稳定性和光电性质研究

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原子与分子物理学报 2025年第2期42卷 182-188页

作者：张仁杰陶红帅郝启圣内蒙古工业大学理学院呼和浩特010051

采用基于密度泛函理论的第一性原理,计算了本征CsPbI_(3)和Mn、Zn、Sn掺杂体系的形成能、电子结构和光学性质.研究结果表明:Mn、Zn、Sn的掺入减小了材料晶格常数,Mn原子掺入CsPbI_(3)晶体结构使得体系的磁矩由0变为5.00μ_(B),丰富了材... 详细信息

采用基于密度泛函理论的第一性原理,计算了本征CsPbI_(3)和Mn、Zn、Sn掺杂体系的形成能、电子结构和光学性质.研究结果表明:Mn、Zn、Sn的掺入减小了材料晶格常数,Mn原子掺入CsPbI_(3)晶体结构使得体系的磁矩由0变为5.00μ_(B),丰富了材料磁性.与Zn掺杂体系相比,Mn、Sn掺杂体系更为稳定.Mn掺杂体系增大了材料带隙,Zn、Sn的掺入使材料带隙分别减小了30.2%和16.2%,有利于电子极化跃迁,但Zn掺入使CsPbI_(3)材料转变为间接带隙半导体.在可见光区域中Mn、Zn、Sn掺杂体均表现出优异的光学性能,Sn掺杂体系效果最佳.这些研究结果为实验方面CsPbI_(3)材料的掺杂改性提供了数据支持,有利于CsPbI_(3)钙钛矿在光电领域的应用.

关键词： CsPbI_(3) 第一性原理电子结构光学性质

Effect of damage on gas seepage behavior of sandstone specimens

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Journal of Rock Mechanics and Geotechnical Engineering 2020年第4期12卷 866-876页

作者： sheng-qi Yang Yan-Hua Huang State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil EngineeringChina University of Mining and TechnologyXuzhou221116China

In underground engineering,such as geological CO2 sequestration,unconventional oil and gas exploration,and radioactive waste storage,permeability of rock is important to evaluate the potential CO2 storage capacity,improve oil and gas production,and prevent leakage of radioactive *** this study,hydrostatic stress tests and triaxial compression tests with gas permeability measurements were carried out on intact and damaged sandstone *** series of experiment were designed to evaluate the permeability evolution laws of sandstone under different testing *** included triaxial seepage tests on intact specimens under different confining pressures,triaxial seepage tests on damaged specimens with different extents of damage,and hydrostatic seepage tests on damaged specimens under increasing and decreasing gas *** on the experimental results,the effects of effective confining pressure,extent of damage and increasing and decreasing gas pressure on permeability of sandstone were *** shows that the permeability of the intact sandstone specimens first decreased and then increased,followed by a constant value with increase in axial *** permeability of the sandstone specimens was observed to decrease with increase in effective confining *** extent of damage affects the permeability evolution,but does not influence the failure patterns of damaged *** the gas pressure increased,the permeability of the damaged sandstone specimen *** the same gas pressure condition,the permeability during the decreasing process is generally higher than that during the increasing *** experiments are expected to enhance our understanding of seepage behavior in underground rock masses.

关键词： Experimental study Sandstone Gas seepage Rock damage Loading and unloading

Integrating potential distribution of dominant vegetation and land use into ecological restoration in the Yellow River Basin,China

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Journal of Mountain Science 2022年第10期19卷 2886-2904页

作者： JIAN sheng-qi ZHU Tian-sheng HU Cai-hong College of Water Resources and Environment Zhengzhou UniversityZhengzhou 450001China

Due to the influence of human activities such as cultivation and urban construction,the ecosystem of the Yellow River Basin(YRB)is subjected to increased vulnerability and even potential risk of *** restoration has led to an increase in vegetation,but excessive afforestation conversely results in low survival rate of trees,water shortages,and biodiversity *** is of great significance for achieving sustainable development of forests to reasonable revegetation in the *** present,the potential distribution pattern of dominant species and their mixed forms in the basin has not been effectively *** study simulated the potential distribution of dominant vegetation in the YRB based on Maximum Entropy(Max Ent)and Genetic Algorithm for Rule-Set Prediction(GARP)and explored the impact of human interference on it by employing land use as the environmental filter to distinguish the regions of human *** further predicted the potential distribution of typically mixed forests and discussed their human *** main results are as follows:(1)Except for Caragana korshinskii,all models had good above performance(0.7

关键词： Yellow River Potential distribution Land use Mixed forests Vegetation restoration

Study on the damage-softening constitutive model of rock and experimental verification

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Acta Mechanica Sinica 2019年第4期35卷 786-798页

作者： sheng-qi Yang Bo Hu Peng Xu State Key Laboratory for Geomechanics and Deep Underground Engineering School of Mechanics and Civil Engineering China University of Mining and Technology Xuzhou 221116 China China Construction Third Engineering Design Bureau Co. Ltd Wuhan 430064 China

A damage-softening model is presented to describe the stress-strain curve of rock. By comparing the Hoek-Brown (H-B) and Mohr-Coulomb (M-C) yield criterion, the equivalent M-C yield criterion is selected as the strength criterion in this model. To better characterize the rock damage and failure processes with considering the relationship between damage and deformation, the concept of yield stress ratio is introduced to describe the yield strengthening deformation before rock peak stress. Damage events are described by two cumulative damage evolution laws. The evolution equations of tensile and shear damage are presented based on the equivalent plastic strains and the maximum value between tensile and shear damage represents the total damage for rock. Considering that rock cannot bear tensile load after tensile failure but still has a certain shear strength, its tensile and shear strengths are small after shear failure. The elastic modulus is affected by tensile damage, whereas the angle of internal friction, the cohesion, and dilation angles are influenced by shear damage. The proposed damage-softening model describes the strain-softening, brittle stress-drop, and residual strength of rock after peak stress, and finally the model is implemented in FLAC3D. Comparing the test and the numerical calculation results, the damage-softening model better describes the total stress-strain curve of rock.

关键词： Rock deformation Damage evolution Softening Numerical calculation

Global Regularity for a 2D Model of Electro-Kinetic Fluid in a Bounded Domain

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Acta Mathematicae Applicatae Sinica 2018年第2期34卷 398-403页

作者： Miao-chao CHEN sheng-qi LU qi-lin LIU School of Applied Mathematics Chaohu University Anhui 238000 China Department of Mathematics and Physics Sanjiang University Jiangsu 210012 China School of Mathematics Southeast University Jiangsu 211189 China

In this paper, we consider an initial boundary value problem for a 2D model of electro-kinetic fluid in a smooth and bounded domain. We prove that the model has a unique global-in-time smooth solution.

关键词： euler equations electro-hydrodynamics global regularity

An Adaptive Routing Algorithm for Integrated Information Networks

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China Communications 2019年第7期16卷 195-206页

作者： Feng Wang Dingde Jiang sheng qi School of Astronautics and Aeronautic University of Electronic Science and Technology of China

The integrated information network is a large capacity information network that integrates various communication platforms on the ground, at sea, in the air and in the deep air through the inter-satellite and satellite-ground links to acquire information accurately, process it quickly, and transmit it efficiently. The satellite communication, as an important part of integrated information networks, is one of main approaches to acquire, process and distribute communication information and resources. In this paper, based on current researches of the satellite communication network, we put forward a 3-layer satellite communication network model based on the Software Defined Network (SDN). Meanwhile, to improve current routing policies of the Low Earth Orbit (LEO) satellite communication network, we put forward an Adaptive Routing Algorithm (ARA) to sustain the shortest satellite communication link. Experiment results show that the proposed method can effectively reduce link distance and communication delay, and realize adaptive path planning.

关键词： integrated information network software defined network satellite communication routing policy adaptive path planning

THE HYDRODYNAMIC CHARACTERISTICS OF FREE VARIABLE-PITCH VERTICAL AXIS TIDAL TURBIN

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Journal of Hydrodynamics 2012年第6期24卷 834-839页

作者： ZHANG Xue-weii WANG Shu-qi WANG Feng ZHANG Liang sheng qi-hu Institute of Ocean Renewable Energy System Harbin Engineering University

The hydrodynamic characteristics of free variable-pitch vertical axis tidal turbine are investigated by combining experimental and numerical simulations. The variations of hydrodynamics are obtained based on testing the kinematics and the dynamics of the turbine under different flow and structural conditions. Through analyzing the movement of the turbine and the characteristics of the flow field by numerical simulations, it is shown how the turbine＇s performance is improved.

关键词： tidal current energy vertical axis variable-pitch turbine hydrodynamic characteristics experiments