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effective stress in soils under different saturation conditions

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Journal of Central South University 2011年第6期18卷 2137-2142页

作者：徐浩峰谢康和 Key Laboratory of Soft Soils and Geoenvironmental Engineering of Ministry of Education Zhejiang University Ningbo Institute of Technology Zhejiang University

BISHOP’s effective stress or two state stress variables are unsatisfactory for unsaturated soils where one of fluid phases is discontinuous, so new expressions of effective stress should be founded. The approach for derivation was according to the principle of equilibrium of forces (i.e., the stress-sharing principle), and it was firstly validated by demonstrating TERZAGHI’s principle of effective stress. And then, the derivations were subdivided into four parts according to different pore air states: 1) air bubbles were spherical and suspended in pore water; 2) air bubbles were bound on soil skeleton; 3) air bubbles held almost the single section of pore; 4) air phase was continuous. The different formulae of effective stress were presented. Conclusions are drawn as follows: 1) For nearly-saturated soils, the "real" effective stress would be a little smaller than TERZAGHI’s effective stress; 2) For soils in which air phase is discontinuous in the form of bubbles, a new concept of pore air elastic pressure is put forward, and the total stress can be constituted by effective stress, pore water pressure and pore air elastic pressure; 3) For soils in which air phase is continuous, effective stress is equal to the value of the total stress plus suction; 4) Suction can be divided into two parts: one is the effect caused by additional pressure, and the other is the contract action by the "skin".

关键词： unsaturated soils effective stress suction surface tension occluded gas saturation

effective stress LAWS FOR MULTI_POROSITY MEDIA

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Applied Mathematics and Mechanics(English Edition) 1999年第11期20卷 1207-1213页

作者：陈勉陈至达 Rock Mechanics Laboratory University of Petroleum Changping 102200 Beijing P R China China University of Mining & Technology Beijing Campus 100083 Beijing P R China

In this paper, the effective stress for multi-porosity elasticity model is presented by means of stress analysis for double porosity media elements. It is found that the effective stress law is not unique, it depends on the hypothesis of constitutive equations for multi-porosity media. Diversified effective stress laws for multi-porosity are developed.

关键词： multi-porosity media porosity fracture effective stress

effective stress AND STRAIN IN FINITE DEFORMATION

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Applied Mathematics and Mechanics(English Edition) 2004年第5期25卷 595-604页

作者：周喆秦伶俐黄文彬王红卫 Applied Mechanics Institute China Agricultural University

Whether the concept of effective stress and strain in elastic-plastic theory is still valid under the condition of finite deformation was mainly discussed. The uni-axial compression experiments in plane stress and plane strain states were chosen for study. In the two kinds of stress states, the stress-strain curve described by logarithm strain and rotated Kirchhoff stress matches the experiments data better than the curves defined by other stress-strain description.

关键词： finite deformation plastic constitutive effective stress effective strain volume invariability

effective stress analysis method of seismic response for high tailings dam

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Journal of Central South University of Technology 2007年第1期14卷 129-134页

作者：柳厚祥李宁廖雪吴从师潘旭东 Institute of Geotechnical Engineering Changsha University of Science and Technology Institute of Geotechnical Engineering Xi'an University of Technology Communications Bureau of Hunan Province

Based on the analysis method for tailings dam in upstream raising method presently used in metallurgy and nonferrous metals tailings depository in the world, an effective stress analysis method of seismic response for high tailings dam was developed according to the results of engineering geological exploration, static and dynamic test and stability analysis on Baizhishan tailing dam 113.5 m high. The law of generation, diffusion and dissipation of seismic pore water pressure during and after earthquake was investigated, and the results of tailings dam’s acceleration, seismic dynamic stress and pore water pressure were obtained. The results show that the seismic stability and liquefaction resistance of high tailings dam are strengthened remarkably, and the scope and depth of liquefaction area at the top of dam are reduced greatly. The interior stress is compressive stress, the stress level of every element is less than 1.0 and the safety coefficient of every element is greater than 1.0. The safety coefficient against liquefaction of every element of tailing dam is greater than 1.5 according to the effective stress analysis of seismic response by finite element method. The calculated results prove that liquefaction is the main reason of seismic failure of high tailing dams, and the effect of seismic inertia forces on high tailing dams’ stability during earthquake is secondary reason.

关键词： tailings dam seismic response effective stress nonlinear analysis against liquefaction upstream raising method

effective stress law for anisotropic double porous media

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Chinese Science Bulletin 2004年第21期49卷 2327-2331页

作者： ZHAO Ying CHEN Mian ZHANG Guangqing School of Oil&Gas Engineering University of PetroleumBeijing102249China

An effective stress law is derived analytically to describe the effect of pore (fracture pore and matrix-block pore) fluid pressure on the linearly elastic response of ani- sotropic saturated dual-porous rocks, which exhibit anisot- ropy. For general anisotropy the difference between the ef- fective stress and the applied stress is not hydrostatic simply multiplied by Biot coefficient. The effective stress law in- volves four constants for transversely isotropic response; these constants can be expressed in terms of the moduli of the single porous material, double porous material and of the solid material. These expressions are simplified considerably when the anisotropy is structural rather than intrinsic, i.e. in the case of an isotropic solid material with an anisotropic pore structure. In this case the effective stress law involves grain bulk modulus, four moduli and two compliances of the porous material for transverse isotropy. The law reduces, in the case of isotropic response, to that suggested by Li Shuiquan (2001). And reduction to the single-porosity (de- rived analytically by Carroll (1979)) is presented to demon- strate the conceptual consistency of the proposed law.

关键词： anisotropy single porous media double porous media pore fracture effective stress

Impact of effective stress on permeability for carbonate fractured-vuggy rocks

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第3期16卷 942-960页

作者： Ke Sun Huiqing Liu Juliana Y.Leung Jing Wang Yabin Feng Renjie Liu Zhijiang Kang Yun Zhang State Key Laboratory of Petroleum Resources and Prospecting China University of PetroleumBeijing102249China School of Mining&Petroleum Engineering University of AlbertaEdmontonT6G 1H9Canada SINOPEC Petroleum Exploration and Production Research Institute Beijing100083China

To gain insight into the flow mechanisms and stress sensitivity for fractured-vuggy reservoirs,several core models with different structural characteristics were designed and fabricated to investigate the impact of effective stress on permeability for carbonate fractured-vuggy rocks(CFVR).It shows that the permeability performance curves under different pore and confining pressures(*** stress conditions)for the fractured core models and the vuggy core models have similar change *** ranges of permeability variation are significantly wider at high pore pressures,indicating that permeability reduction is the most significant during the early stage of development for fractured-vuggy *** each obtained effective stress coefficient for permeability(ESCP)varies with the changes in confining pressure and pore pressure,the effective stresses for permeability of four representative CFVR show obvious nonlinear characteristics,and the variation ranges of ESCP are all between 0 and ***,a comprehensive ESCP mathematical model considering triple media,including matrix pores,fractures,and dissolved vugs,was *** is proved theoretically that the ESCP of CFVR generally varies between 0 and ***,the regression results showed that the power model ranked highest among the four empirical models mainly applied in stress sensitivity characterization,followed by the logarithmic model,exponential model,and binomial *** concept of“permeability decline rate”was introduced to better evaluate the stress sensitivity performance for CFVR,in which the one-fracture rock is the strongest,followed by the fracture-vug rock and two-horizontalfracture rock;the through-hole rock is the *** general,this study provides a theoretical basis to guide the design of development and adjustment programs for carbonate fractured-vuggy reservoirs.

关键词： effective stress Permeability Carbonate fractured-vuggy rocks Structure characteristics stress sensitivity

Examination of effective stress in clay rock

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Journal of Rock Mechanics and Geotechnical Engineering 2017年第3期9卷 97-107页

作者： Chun-Liang Zhang Gesellschaft für Anlagen- und Reaktorsicherheit (GRS) Braunschweig 38122 Germany

This paper examines the effective stress in indurated clay rock theoretically and experimentally.A stress concept is derived from the analysis of the microstructure and of the pore water in the highly-indurated Callovo-Oxfordian and Opalinus clay rocks,and subsequently validated by various experiments performed on these *** concept suggests that the interparticle or effective stress in a dense clay ewater system is transferred through both the adsorbed interparticle pore water in narrow pores and the solidesolid contact between non-clay mineral *** experiments show that the adsorbed pore water in the claystones is capable of bearing deviatoric effective stresses up to the failure *** applied stresses are for the most part or even totally transferred by the bound pore water,*** swelling pressure in the interparticle bound pore water is almost equivalent to the effective *** stress concept provides a reasonable view to the nature of the effective stress in argillaceous rock and forms the fundamental basis for studies of the hydro-mechanical properties and processes in clay formations.

关键词： Clay rock stress analysis effective stress Swelling pressure Experiment

Experiment study on the law of effective stress of coal masses during methane drainage

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Journal of Coal Science & Engineering(China) 2007年第4期13卷 444-447页

作者：冯增朝吕兆兴赵阳升 Institute of Mining Technology Taiyuan University of Technology Taiyuan 030024 China

The methane drainage can not only make coal seams deformation, but also effect its stress distribution. Based on lab experiment on methane drainage with a cubic coal sample of 500 mm×500 mm×500 mm, mutative law of coal of pore pressure （p） and effective stress （σef）i were investigated during methane drainage with the coal sample of China Lu＇an coal field No.3 coal seam. The experiment results indicate： during methane drainage pore pressure （p） follows exponential attenuation law： p=aexp（-bt）; effective stress （σef）i of coal masses follows logarithm incremental law：（σef）,=aln t＋b, （i=x, y, z）; effective stress coefficient（a） follows logarithm attenuation law： a=a-bln t; effective stress coefficient, volume stress （Θef） and pore pressure （p） follow bilinear law.

关键词： methane coal masses effective stress experiment study

Evaluation of effective stresses and State Surfaces for Unsaturated Clayey Silt

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Journal of Environmental Science and Engineering(B) 2014年第4期3卷 181-189页

作者： Hisashi Suzuki Department of Civil and Environmental Engineering Tokushima University Tokushima 770-8506 Japan

Terzaghi had established soil mechanics as an academic scholarship due to the discovery of the principal of effective stress for saturated soils when he considered the consolidation theory of saturated clay. The reason of the existence of the effective stress is that soil particles and water are composited by incompressible solid and liquid. Although air is very compressible fluid, the principle of effective stress is also used in unsaturated soils in the resent developed numerical analyses. Schrefler＇s equation is most frequently used, but the effective stress is not verified by the experimental results. In this study, the equations for unsaturated soils proposed by Schrefler, Aitchison, Khalili and Khabbaz and Kohgo are compared with using the results of suction controlled consolidometer tests. As a result, the effective stress for unsaturated soils calculated by Schrefler＇s equation was average of them.

关键词： Unsaturated soil effective stress state surface consolidometer test.