The stability of dams and their foundations is an important problem to which dam engineers have paid close attention over the years. This paper presented two methods to analyze the stability of a gravity dam and its f...The stability of dams and their foundations is an important problem to which dam engineers have paid close attention over the years. This paper presented two methods to analyze the stability of a gravity dam and its foundation. The direct analysis method was based on a rigid limit equilibrium method which regarded both dam and the rock foundation as undeformable rigid bodies. In this method, the safety factor of potential sliding surfaces was computed directly. The second method, the indirect analysis method, was based on elasto-plastic theory and employs nonlinear finite element method (FEM) in the analysis of stresses and deformation in the dam and its foundation. The determination of the safety degree of the structure was based on the convergence and abrupt the change criterion. The results obtained showed that structures' constituent material behavior played an active role in the failure of engineered structures in addition to the imposed load.展开更多
Flexible flowlines and risers have been increasingly used for deepwater and ultra-deepwater field applications,partially because of its low submerged weight and better dynamic characteristics comparing to rigid pipeli...Flexible flowlines and risers have been increasingly used for deepwater and ultra-deepwater field applications,partially because of its low submerged weight and better dynamic characteristics comparing to rigid pipelines. The offshore installation of flowline may have advantages as well. However,it has special needs for the in-stallation aids,and it is challenging to install tie-in structures due to its low bending stiffness. This paper is to present some of the challenges during a recent flexible installation project with a total of more than 100 km flexible flowlines,and 24 in-line sleds/pipeline end termination(PLET) in water depth up to 1 300 m.展开更多
Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ens...Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ensuring the structural stability and avoiding the wrinkling of membrane structures.In this paper,the analysis procedures are presented and the wrinkling of membrane structure,representing a major behavioral performance of the structure,is included with the modified constitutive relationship method.As for the judgment of the membrane wrinkling,the principal stress-strain criteria are incorporated.Thereafter,an integrated algorithm is developed,in which the Newton-Raphson method and updated Lagrange formulation are adopted.With the proposed algorithm,two fabric roof structures are analyzed.Results show that the presented method is feasible and reliable.展开更多
文摘The stability of dams and their foundations is an important problem to which dam engineers have paid close attention over the years. This paper presented two methods to analyze the stability of a gravity dam and its foundation. The direct analysis method was based on a rigid limit equilibrium method which regarded both dam and the rock foundation as undeformable rigid bodies. In this method, the safety factor of potential sliding surfaces was computed directly. The second method, the indirect analysis method, was based on elasto-plastic theory and employs nonlinear finite element method (FEM) in the analysis of stresses and deformation in the dam and its foundation. The determination of the safety degree of the structure was based on the convergence and abrupt the change criterion. The results obtained showed that structures' constituent material behavior played an active role in the failure of engineered structures in addition to the imposed load.
文摘Flexible flowlines and risers have been increasingly used for deepwater and ultra-deepwater field applications,partially because of its low submerged weight and better dynamic characteristics comparing to rigid pipelines. The offshore installation of flowline may have advantages as well. However,it has special needs for the in-stallation aids,and it is challenging to install tie-in structures due to its low bending stiffness. This paper is to present some of the challenges during a recent flexible installation project with a total of more than 100 km flexible flowlines,and 24 in-line sleds/pipeline end termination(PLET) in water depth up to 1 300 m.
基金supported by the National Natural Science Foundation of China (Grant Nos. 90815021,50725826)
文摘Loading analysis,as one of the most crucial procedures in the assessment of safety of the membrane structures,is to check the adequacy of structural stiffness and the extent of membrane stress and deformation,thus ensuring the structural stability and avoiding the wrinkling of membrane structures.In this paper,the analysis procedures are presented and the wrinkling of membrane structure,representing a major behavioral performance of the structure,is included with the modified constitutive relationship method.As for the judgment of the membrane wrinkling,the principal stress-strain criteria are incorporated.Thereafter,an integrated algorithm is developed,in which the Newton-Raphson method and updated Lagrange formulation are adopted.With the proposed algorithm,two fabric roof structures are analyzed.Results show that the presented method is feasible and reliable.
