Leng F.,Hohai University |
Leng F.,National Dam Safety Research Center |
Wu G.,Jiangsu Provincial Communications Planning and Design Institute
European Journal of Environmental and Civil Engineering | Year: 2013
A thermodynamics-based damage constitutive model is developed for concrete, which describes tensile and compressive damage well and follows the second thermodynamic law. Constitutive model should meet general thermodynamics, while it describes behaviour characteristic of concrete material, which are often not able to be satisfied by existing models because of various of hypotheses. Generalised stress functions and dissipative generalised stress functions are constructed from free energy function and energy dissipation function according to the physical meaning of the thermodynamic potential and the characteristic of the constitutive model of concrete. Then, a damage constitutive model of concrete is developed and the parameters of the model are identified. The numerical method of the model is also presented. The model in the paper can satisfy the second thermodynamic law automatically and simulate the tensile and compressive behaviour of concrete well. Finally, the feasibility and practicality of the model is verified by the analysis of classical experiments and Koyna dam. © 2013 Taylor and Francis.
Lei X.L.,Chongqing Academy of Science and Technology CAST |
Li L.,Chongqing Jiaotong University |
Wan J.,Chongqing Jiaotong University |
He D.K.,Jiangsu Provincial Communications Planning and Design Institute
Advanced Materials Research | Year: 2013
This task studies the impacts and mechanisms of intermittent aeration and movement degree of membrane on the permeate flux in a submerged membrane system. The contents includes: Analysis of the effects of intermittent aeration on the membrane performance, modelling the experimental results and find out the mechanisms; Analysis of the effects of different movement degree of membrane on the permeate flux during the intermittent aeration process, modelling the experimental results and find out the mechanisms; Determination of the optimum membrane running conditions, including the most effective intensity of gas sparging, the most effective intermittent aeration cycle time and the most effective movement degree of membrane, etc. It shows that intermittent aerations between backwashing processes can significantly improve the membrane performance; the change of the movement degree(L/H),which means the ratio of the effective length and the effective vertical height) of membrane can affect the influences of intermittent aeration on the membrane performance significantly; the most effective intensity of gas sparging is 1.5L/h; the most effective intermittent aeration cycle time is 30min; the most effective movement degree of membrane is 1.07.The result of the research is good for the selection of operation condition and determination of running parameters of ultrafiltration membrane water supply process. © (2013) Trans Tech Publications, Switzerland.
Li D.-M.,Nanjing Southeast University |
Li D.-M.,Jiangsu Provincial Communications Planning and Design Institute |
Li W.-Q.,Nanjing Southeast University |
Li R.,Nanjing Southeast University
Beijing Ligong Daxue Xuebao/Transaction of Beijing Institute of Technology | Year: 2012
Comprehensive safety evaluation of intersection was presented. Based on the traffic accident statistics and traffic conflict technique, the safety evaluation method was proposed. Using statistics of the economic and social development index and the measured data of intersections, the evaluation model was calibrated. A regression model between traffic accident ratio and traffic conflict was established and the traffic risk factors was introduced to evaluate the intersection of the level of traffic safety. The results indicated that the traffic risk factors did not rely on the traffic accident statistics and extensive applicable range.
Chu F.-Y.,Hohai University |
Chu F.-Y.,Lishui University |
Zhu J.-G.,Hohai University |
Wang P.,Hydro China Chengdu Design and Research Institute |
And 2 more authors.
Yantu Lixue/Rock and Soil Mechanics | Year: 2012
Using large-scale shearing device, K 0 consolidated-drained triaxial test and isotropically consolidated-drained triaxial test under different confining pressures are performed for three relative density overburden material of Shuangjiangkou earth dam. The behaviour of coarse-grained soil under K 0-consolidation is investigated. The test results from K 0 consolidated-drained tests are compared with those from isotropically consolidated-drained tests. The results show that the relationship between mean principal stress and volumetric strain and between deviatoric stress and deviatoric strain during the K 0-consolidation can be fitted with power function. In the stage with steady pressure after K 0-consolidation, the strain-time curve can be fitted with exponential function. The strength of K 0 consolidated-drained triaxial shear test is slight greater than that of isotropically consolidated-drained test. The initial elastic modulus E i and Poisson's ratio v i obtained from K 0 consolidated-drained triaxial test is larger than that from isotropically consolidated-drained test. The dilatancy K 0-consolidated sample is more evident.
Gu Y.-C.,Jiangsu Provincial Communications Planning and Design Institute |
Tang Z.-J.,Fujian Provincial Freeway Co. |
Hu G.-W.,Jiangsu Provincial Communications Planning and Design Institute
Wuhan Ligong Daxue Xuebao/Journal of Wuhan University of Technology | Year: 2010
Applying for BISAR software, according to the typical structures of flexible base asphalt pavement, distribution rules of vertical elastic strain inside of the pavement was calculated out. The variation rule of thermal was calculated out by method of AI, and dynamic modulus of hot mixture asphalt varying with thermal was also calculated out by equation of dynamic modulus. Besides, the relation between plastic strain, thermal and elastic strain was got by prediction model in AASHTO2002, the variation rules of plastic strain with depth was built. Choosing the parameters such as elastic strain according to the depth of average plastic strain, temperatures, load times, asphalt course thickness and permanent deformation of pavement, the design equation of resistance to permanent deformation of flexible base asphalt pavement was got based on regression analysis. The results show that this design equation has good correlation.