Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation st...Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation steps for contact forces,semi-spring and semi-edge are introduced in calculation.Semispring is derived from block vertex,and formed by indenting the block vertex into each face(24semisprings for a hexahedral element).The formation process of semi-edge is the same as that of semi-spring(24semi-edges for a hexahedral element).Based on the semi-springs and semi-edges,a new type of combined contact model is presented.According to this model,six contact types could be reduced to two,i.e.the semi-spring target face contact and semi-edge target edge contact.By the combined model,the contact force could be calculated directly(the information of contact type is not necessary),and the failure judgment could be executed in a straightforward way(each semi-spring and semi-edge own their characteristic areas).The algorithm has been successfully programmed in C++program.Some simple numerical cases are presented to show the validity and accuracy of this model.Finally,the failure mode,sliding distance and critical friction angle of Jiweishan landslide are studied with the combined model.展开更多
To simulate the progressive failure of slope,a block particle coupled model is introduced.Particle oriented cell mapping(POCM)algorithm is used to enhance the search efficiency,and particlepoint,particle-edge,particle...To simulate the progressive failure of slope,a block particle coupled model is introduced.Particle oriented cell mapping(POCM)algorithm is used to enhance the search efficiency,and particlepoint,particle-edge,particle-face contact detecting method is adopted to establish contact pair between particles and blocks precisely.Strain softening Mohr Coulomb model with tensile cutoff is adopted for blocks,and brittle Mohr Coulomb model is used for particles.The particle-block replacement approach is used to describe the fracture and fragmentation process of continuum media.Once the cohesion or tensile strength of one block reaches zero,the block will be deleted,and particles are generated at the same place with all information inherited from the deleted block.Some numerical cases related to landslides demonstrate the precision and rationality of the coupled model.展开更多
In order to investigate the expression of glycerol-3 -phosphate dehydrogenase by GCY1 gene in recombinant Saccharomyces cerevisiae, induction culture of the S. cerevisiaestrain was performed with SD-URA 2% galactose, ...In order to investigate the expression of glycerol-3 -phosphate dehydrogenase by GCY1 gene in recombinant Saccharomyces cerevisiae, induction culture of the S. cerevisiaestrain was performed with SD-URA 2% galactose, 3 × YP + 6% glucose, SC-URA 2% galactose, and SC-URA 2% galactose + 5% NaCI glyeerol-3-phosphate dehydregenase, the cultured S. cerevisiaewas comminuted followed by full-automatic high-speed purification, and SDS-PAGE gel electrophoresis was performed for molecular weight of the GST fusion protein. The results showed that after shaking culture of the S. cerevisiae containing GCY1 at 25 ℃, the OD values of its 3 × YP + 6% glucose culture and SC-URA 2% galaetose + 5% NaC1 culture were 8.75 and 7.35, respectively. It was shown by purification with a Profinia low-pressure liquid chromatograph that only the S. cerevisiae cultured in SC-URA 2% galactose + 5% NaC1 medium expressed glycerel-3-phosphate de- hydrogenase, the molecular weight of which was detected as 65 ku by SDS-PAGE gel electrophoresis.展开更多
Aiming at the progressive damage phenomenon in geotechnical field,it attempts to study the effect of progressive damage on the macro-bearing capacity.Firstly,based on the theoretical analysis of a two-dimensional plan...Aiming at the progressive damage phenomenon in geotechnical field,it attempts to study the effect of progressive damage on the macro-bearing capacity.Firstly,based on the theoretical analysis of a two-dimensional plane inside representative volume element,it is proposed that progressive damage will occur if the bearing capacity of microplanes is different.Besides,“damage-aggravation effect”is proposed according to the difference between the macro-bearing capacity of entire plane and the sum of bearing capacity of all microplanes when progressive damage occurs.Secondly,progressive damage ratio K_(t)is proposed to quantify“damage-aggravation effect”.Finally,based on the rod model,the correspondence between K_(t),and some influence factors is studied by theoretical analysis and numerical simulation.The results show that“damage-aggravation effect”does exist,and the macro-bearing capacity of entire plane is less than the sum of bearing capacity of all microplanes when progressive damage occurs.If the bearing capacity of rods in the rod model obeys uniform distribution,as the minimum of bearing capacity increases linearly,the macro-bearing capacity increases linearly,and K_(t)decreases inversely.展开更多
A three-stage model is introduced to describe the tensile failure process of rock and concrete materials.Failure of the material is defined to contain three stages in the model,which include elastic deformation stage,...A three-stage model is introduced to describe the tensile failure process of rock and concrete materials.Failure of the material is defined to contain three stages in the model,which include elastic deformation stage,body damage stage and localization damage stage.The failure mode change from uniform body damage to localization damage is expressed.The heterogeneity of material is described with strain strength distribution.The fracture factor and intact factor,defined as the distribution function of strain strength,are used to express the fracture state in the failure process.And the distributive parameters can be determined through the experimental stress-strain curve.展开更多
基金the National Basic Research Program of the Ministry of Science and Technology of China (Grant No. 2010CB731506)the National Key Technology Research and Development Program of the Ministry of Science and Technology of China (Grant No. 2012BAK10B01)the Youth Science Fund of National Natural Science Foundation of China (Grant No. 11302230)
文摘Continuum-based discrete element method(CDEM)is an explicit numerical method used for simulation of progressive failure of geological body.To improve the efficiency of contact detection and simplify the calculation steps for contact forces,semi-spring and semi-edge are introduced in calculation.Semispring is derived from block vertex,and formed by indenting the block vertex into each face(24semisprings for a hexahedral element).The formation process of semi-edge is the same as that of semi-spring(24semi-edges for a hexahedral element).Based on the semi-springs and semi-edges,a new type of combined contact model is presented.According to this model,six contact types could be reduced to two,i.e.the semi-spring target face contact and semi-edge target edge contact.By the combined model,the contact force could be calculated directly(the information of contact type is not necessary),and the failure judgment could be executed in a straightforward way(each semi-spring and semi-edge own their characteristic areas).The algorithm has been successfully programmed in C++program.Some simple numerical cases are presented to show the validity and accuracy of this model.Finally,the failure mode,sliding distance and critical friction angle of Jiweishan landslide are studied with the combined model.
基金supported by the National Key Research and Development Project of China,the Ministry of Science and Technology of China(Grant 2018YFC1505504)。
文摘To simulate the progressive failure of slope,a block particle coupled model is introduced.Particle oriented cell mapping(POCM)algorithm is used to enhance the search efficiency,and particlepoint,particle-edge,particle-face contact detecting method is adopted to establish contact pair between particles and blocks precisely.Strain softening Mohr Coulomb model with tensile cutoff is adopted for blocks,and brittle Mohr Coulomb model is used for particles.The particle-block replacement approach is used to describe the fracture and fragmentation process of continuum media.Once the cohesion or tensile strength of one block reaches zero,the block will be deleted,and particles are generated at the same place with all information inherited from the deleted block.Some numerical cases related to landslides demonstrate the precision and rationality of the coupled model.
基金Supported by Social Service Project of New Countryside Development Research Institute of Yangtze University(201411)
文摘In order to investigate the expression of glycerol-3 -phosphate dehydrogenase by GCY1 gene in recombinant Saccharomyces cerevisiae, induction culture of the S. cerevisiaestrain was performed with SD-URA 2% galactose, 3 × YP + 6% glucose, SC-URA 2% galactose, and SC-URA 2% galactose + 5% NaCI glyeerol-3-phosphate dehydregenase, the cultured S. cerevisiaewas comminuted followed by full-automatic high-speed purification, and SDS-PAGE gel electrophoresis was performed for molecular weight of the GST fusion protein. The results showed that after shaking culture of the S. cerevisiae containing GCY1 at 25 ℃, the OD values of its 3 × YP + 6% glucose culture and SC-URA 2% galaetose + 5% NaC1 culture were 8.75 and 7.35, respectively. It was shown by purification with a Profinia low-pressure liquid chromatograph that only the S. cerevisiae cultured in SC-URA 2% galactose + 5% NaC1 medium expressed glycerel-3-phosphate de- hydrogenase, the molecular weight of which was detected as 65 ku by SDS-PAGE gel electrophoresis.
基金The authors would like to acknowledge the financial support of the National Key Research and Development Project of China,the Ministry of Science and Technology of China(Grant 2018 YFC1505504).
文摘Aiming at the progressive damage phenomenon in geotechnical field,it attempts to study the effect of progressive damage on the macro-bearing capacity.Firstly,based on the theoretical analysis of a two-dimensional plane inside representative volume element,it is proposed that progressive damage will occur if the bearing capacity of microplanes is different.Besides,“damage-aggravation effect”is proposed according to the difference between the macro-bearing capacity of entire plane and the sum of bearing capacity of all microplanes when progressive damage occurs.Secondly,progressive damage ratio K_(t)is proposed to quantify“damage-aggravation effect”.Finally,based on the rod model,the correspondence between K_(t),and some influence factors is studied by theoretical analysis and numerical simulation.The results show that“damage-aggravation effect”does exist,and the macro-bearing capacity of entire plane is less than the sum of bearing capacity of all microplanes when progressive damage occurs.If the bearing capacity of rods in the rod model obeys uniform distribution,as the minimum of bearing capacity increases linearly,the macro-bearing capacity increases linearly,and K_(t)decreases inversely.
基金Project supported by the National Program on Key Basic Research Project of China(973 Program,No.2015CB250903)CAS Strategic Priority Research Program(B)(No.XDB10030303)
文摘A three-stage model is introduced to describe the tensile failure process of rock and concrete materials.Failure of the material is defined to contain three stages in the model,which include elastic deformation stage,body damage stage and localization damage stage.The failure mode change from uniform body damage to localization damage is expressed.The heterogeneity of material is described with strain strength distribution.The fracture factor and intact factor,defined as the distribution function of strain strength,are used to express the fracture state in the failure process.And the distributive parameters can be determined through the experimental stress-strain curve.