How to model the permeability evolution of rock subjected to liquid nitrogen cooling is a key issue. This paper proposes a simple but practical method to study the permeability evolution of rocks subject to liquid nit...How to model the permeability evolution of rock subjected to liquid nitrogen cooling is a key issue. This paper proposes a simple but practical method to study the permeability evolution of rocks subject to liquid nitrogen cooling. FLAC with FISH function was employed to numerically model the rock behavior under cooling. The enhanced perme- ability of the volumetric strain was defined, and the permeability was directly evaluated based on element's volumetric strain. Detailed procedures for implementing the evolution model of permeability in this paper were presented. A case study was carried out to simulate a coal bed where liquid nitrogen was injected in the bore hole. And a semi-submerged test of liquid nitrogen was performed. The method to model the permeability evolution of rocks subject to liquid nitrogen shock in this paper was proved to be right by the test results. This simulation results are discussed with the hope to provide some insight into understanding the nitrogen cooling practice.展开更多
The laboratory tests on the post-liquefaction deformation of saturated sand-gravel composites were performed to investigate the characteristics of stress-strain relation and the dissipation of pore water pressure by t...The laboratory tests on the post-liquefaction deformation of saturated sand-gravel composites were performed to investigate the characteristics of stress-strain relation and the dissipation of pore water pressure by the hollow cylinder apparatus. It is found that the stress-strain response and the dissipation process of pore water pressure are composed of three stages, including the low intensive strength stage, the superlinear strength recovery stage and the sublinear strength recovery stage, and the demarcation points of the curve of pore water pressure are lag behind those of the stress-strain response. The comparison results of the behaviour of large post-liquefaction deformation between saturated sand-gravel composites and Nanjing fine sand show that the low intensive strength stage and the superlinear strength recovery stage of saturated sand-gravel composites are shorter while the sublinear strength recovery stage is longer. A stress-strain model and a dissipation model of excess pore water pressure of liquefied sand-gravel composites are established, in which the initial confining pressure and the relative density can be considered synthetically. And it is found that the predicted results by the two models are in good agreement with experimental data.展开更多
This paper mainly investigates the effects of initial static shear stress and grain shape on the liquefaction induced large deformation of saturated sand under torsional shear.Nanjing sand,mainly composed of platy gra...This paper mainly investigates the effects of initial static shear stress and grain shape on the liquefaction induced large deformation of saturated sand under torsional shear.Nanjing sand,mainly composed of platy grains,is tested with different initial static shear stress ratio(SSR)using a hollow column torsional shear apparatus.The tests find that the saturated Nanjing sand reaches full liquefaction under the superposition of initial static shear stress and cyclic stress for both stress reversal and non-reversal cases.However,it requires a large number of loading cycles to reach full liquefaction if stress reversal does not occur.With increasing the initial static stress,the large deformation of the Nanjing sand should mainly induced by the cyclic liquefaction firstly under a smaller initial shear stress,and then it should be induced by the residual deformation failure.The critical point occurs approximately when the initial shear stress is close to the amplitude of the cyclic shear stress.Meanwhile,it shows that grain angularity increases the liquefaction resistance when the initial static shear stress is zero.A small initial static shear stress causes the larger loss of liquefaction resistance for angular sand than rounded sand.At a high initial SSR,the angular sand is more resistant to the large residual deformation failure than the rounded sand.展开更多
Adding the polyamine inhibitor into drilling fluid can effectively strengthen the rejection capability and improve the rheological behavior of drilling fluid system. According to the analysis of the comparison of the ...Adding the polyamine inhibitor into drilling fluid can effectively strengthen the rejection capability and improve the rheological behavior of drilling fluid system. According to the analysis of the comparison of the physiochemical properties of the polyamine inhibitor, a polyamine polymer drilling fluid system was established by means of adding UAE polyamine into traditional polymer drilling fluid. Conventional properties and environmental influence of this system have been evaluated in this paper. The result indicates that the polymer drilling fluid system optimized by polyamine shows a high-performance, such as excellent rejection performance, better rheological and filtration properties, better environmental protection functions. Thus it can be used in high water-sensitive, high temperature, high pressure or vulnerable formation drilling operations.展开更多
This study focuses on the stress and displacement of a circular opening that is excavated in a strain-softening rock mass under hydraulic-mechanical coupling.It follows the generalized Hoek-Brown(H-B) failure criterio...This study focuses on the stress and displacement of a circular opening that is excavated in a strain-softening rock mass under hydraulic-mechanical coupling.It follows the generalized Hoek-Brown(H-B) failure criterion.Moreover,an improved numerical method and stepwise procedure are proposed.This method considers the deterioration of the strength,deformation,and dilation angle.It also incorporates the hydraulic-mechanical coupling and the variation of elastic strain in the plastic region.Several examples are conducted to demonstrate the validity and accuracy of the proposed solution through MATLAB programming and FLAC software.Parametric studies are also conducted to highlight the influence of hydraulic–mechanical coupling on stress and displacement.Results show that in this case,stress confinement is lower and tunnel convergences are higher than the corresponding stresses and displacements obtained when those factors are not considered.The displacement and plastic radius are also larger than those obtained when hydraulic-mechanical coupling is not considered.展开更多
The "solidified liquid layer" model has been examined using a quartz crystal microbalance(QCM) with a polymeric matrix.The model is shown to give a reasonable explanation for the following experimental obser...The "solidified liquid layer" model has been examined using a quartz crystal microbalance(QCM) with a polymeric matrix.The model is shown to give a reasonable explanation for the following experimental observations:(i) The opposite response of the QCM and surface plasmon resonance(SPR) for the activation process;(ii) the marked difference in the responses for IgG/anti-IgG interaction between QCM and SPR.Theoretical analysis and experimental results indicated that QCM is sensitive to the thickness change of the "solidified liquid layer" but not the mass of captured biomolecules(i.e.,the immobilized mass),implying caution must be taken in interpreting QCM results.展开更多
文摘How to model the permeability evolution of rock subjected to liquid nitrogen cooling is a key issue. This paper proposes a simple but practical method to study the permeability evolution of rocks subject to liquid nitrogen cooling. FLAC with FISH function was employed to numerically model the rock behavior under cooling. The enhanced perme- ability of the volumetric strain was defined, and the permeability was directly evaluated based on element's volumetric strain. Detailed procedures for implementing the evolution model of permeability in this paper were presented. A case study was carried out to simulate a coal bed where liquid nitrogen was injected in the bore hole. And a semi-submerged test of liquid nitrogen was performed. The method to model the permeability evolution of rocks subject to liquid nitrogen shock in this paper was proved to be right by the test results. This simulation results are discussed with the hope to provide some insight into understanding the nitrogen cooling practice.
基金Project(90715018)supported by the National Natural Science Foundation of ChinaProject(200808022)supported by the Special Fund for the Commonweal Indusry of China+1 种基金Project(08KJA560001)supported by the Key Basic Research Program of Natural Science of University in Jiangsu ProvinceProject(CX10B_170Z)supported by the Postgraduate Scientific Innovation Program in Jiangsu Province,China
文摘The laboratory tests on the post-liquefaction deformation of saturated sand-gravel composites were performed to investigate the characteristics of stress-strain relation and the dissipation of pore water pressure by the hollow cylinder apparatus. It is found that the stress-strain response and the dissipation process of pore water pressure are composed of three stages, including the low intensive strength stage, the superlinear strength recovery stage and the sublinear strength recovery stage, and the demarcation points of the curve of pore water pressure are lag behind those of the stress-strain response. The comparison results of the behaviour of large post-liquefaction deformation between saturated sand-gravel composites and Nanjing fine sand show that the low intensive strength stage and the superlinear strength recovery stage of saturated sand-gravel composites are shorter while the sublinear strength recovery stage is longer. A stress-strain model and a dissipation model of excess pore water pressure of liquefied sand-gravel composites are established, in which the initial confining pressure and the relative density can be considered synthetically. And it is found that the predicted results by the two models are in good agreement with experimental data.
基金supported by the National Natural Science Foundation of China(Nos.51778290,51778386)the National Science Fund for Distinguished Young Scholars(No.51725802)the Natural Science Foundation of Jiangsu High School(No.16KJA560001)。
文摘This paper mainly investigates the effects of initial static shear stress and grain shape on the liquefaction induced large deformation of saturated sand under torsional shear.Nanjing sand,mainly composed of platy grains,is tested with different initial static shear stress ratio(SSR)using a hollow column torsional shear apparatus.The tests find that the saturated Nanjing sand reaches full liquefaction under the superposition of initial static shear stress and cyclic stress for both stress reversal and non-reversal cases.However,it requires a large number of loading cycles to reach full liquefaction if stress reversal does not occur.With increasing the initial static stress,the large deformation of the Nanjing sand should mainly induced by the cyclic liquefaction firstly under a smaller initial shear stress,and then it should be induced by the residual deformation failure.The critical point occurs approximately when the initial shear stress is close to the amplitude of the cyclic shear stress.Meanwhile,it shows that grain angularity increases the liquefaction resistance when the initial static shear stress is zero.A small initial static shear stress causes the larger loss of liquefaction resistance for angular sand than rounded sand.At a high initial SSR,the angular sand is more resistant to the large residual deformation failure than the rounded sand.
文摘Adding the polyamine inhibitor into drilling fluid can effectively strengthen the rejection capability and improve the rheological behavior of drilling fluid system. According to the analysis of the comparison of the physiochemical properties of the polyamine inhibitor, a polyamine polymer drilling fluid system was established by means of adding UAE polyamine into traditional polymer drilling fluid. Conventional properties and environmental influence of this system have been evaluated in this paper. The result indicates that the polymer drilling fluid system optimized by polyamine shows a high-performance, such as excellent rejection performance, better rheological and filtration properties, better environmental protection functions. Thus it can be used in high water-sensitive, high temperature, high pressure or vulnerable formation drilling operations.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2013CB036004)the National Natural Science Foundation of China(Grant No.51208523)China Postdoctoral Science Foundation(Grant No.2003034468)
文摘This study focuses on the stress and displacement of a circular opening that is excavated in a strain-softening rock mass under hydraulic-mechanical coupling.It follows the generalized Hoek-Brown(H-B) failure criterion.Moreover,an improved numerical method and stepwise procedure are proposed.This method considers the deterioration of the strength,deformation,and dilation angle.It also incorporates the hydraulic-mechanical coupling and the variation of elastic strain in the plastic region.Several examples are conducted to demonstrate the validity and accuracy of the proposed solution through MATLAB programming and FLAC software.Parametric studies are also conducted to highlight the influence of hydraulic–mechanical coupling on stress and displacement.Results show that in this case,stress confinement is lower and tunnel convergences are higher than the corresponding stresses and displacements obtained when those factors are not considered.The displacement and plastic radius are also larger than those obtained when hydraulic-mechanical coupling is not considered.
基金supported by the 100 Talents Programme of Chinese Academy of Sciences(08BM031001)the Fok Ying Tung Education Foundation (114013) to H.M.the National Basic Research Program of China (2009CB320300)
文摘The "solidified liquid layer" model has been examined using a quartz crystal microbalance(QCM) with a polymeric matrix.The model is shown to give a reasonable explanation for the following experimental observations:(i) The opposite response of the QCM and surface plasmon resonance(SPR) for the activation process;(ii) the marked difference in the responses for IgG/anti-IgG interaction between QCM and SPR.Theoretical analysis and experimental results indicated that QCM is sensitive to the thickness change of the "solidified liquid layer" but not the mass of captured biomolecules(i.e.,the immobilized mass),implying caution must be taken in interpreting QCM results.