In order to investigate the sand mold strength after the aeration sand filling-high pressure squeeze moldingprocess,a tree-dimentional(3D)numerical simulation was introduced.The commercial finite element method(FEM)so...In order to investigate the sand mold strength after the aeration sand filling-high pressure squeeze moldingprocess,a tree-dimentional(3D)numerical simulation was introduced.The commercial finite element method(FEM)software ABAQUScombined with a revised Drucker-Prager/Cap model was used to simulate the squeeze compaction process.Additionally,the sand bulk density after the aeration sand filling process was tested by a specially designed experiment,which divided the whole sand bulk in the molding chamber into5x9regions and it was used as the input to simulate the squeeze process.During the simulation process,the uniform modeling simulation and the patition modeling simulation methods were used a d the3D numercal simulation results were compared with correlative benchmark testings.From the3D numerica simulation results,it can be concluded that the uniform sand bulk density distribution can obtain a high quality sandmold and the revised Drncker-Pager/Cap model is suitable for handling the situation with the complex paaern.The3D numerical simulation results can predict well the sand mold strength distribution and can be used as guidelines for the production practice.展开更多
In this paper, a study of sandy soil compaction with different granulometry and moisture content has been performed, and soil mechanical property variations in moisture and granulometry have been investigated. Investi...In this paper, a study of sandy soil compaction with different granulometry and moisture content has been performed, and soil mechanical property variations in moisture and granulometry have been investigated. Investigations were performed to compare hydrostatic compression test （HCT） responses and evaluate the compression index, Cc, which is an indicator of the soil＇s susceptibility to compaction-induced damage. The experiments have been performed on 24 soil samples typologies. Each sample has been obtained by combining three types of soil granulometry （types A, B and C） with a relative content varying from 0% to 100% in 20% increments. Soil type A had a granulometry ranging between 0.5 mm and 1 mm, type B between 0.25 mm and 0.5 mm, and type C less than 0.25 mm. These samples were representative of a sandy soil, chemically inactive and had various granulometries and initial moisture contents. A cell for HCT has been set up to allow the initial volume measurement of the test pieces and the subsequent changes during HCT with an estimated error less than 0.1 cm3. All samples were pre-compacted and prepared in agreement with the actual standards. The experimental data are reported in diagrams, the data allowed comparison of the mechanical behaviors between the considered unsaturated soils and underlined how soil moisture and granulometry affect soil response during HCT. Furthermore, because of the methodology used, the equipment was very economical.展开更多
By using the soil static and dynamic universal triaxial and torsional shear apparatus, a series of combined cyclic shear tests are performed to simulate the rotation in the principal stress direction induced by ocean ...By using the soil static and dynamic universal triaxial and torsional shear apparatus, a series of combined cyclic shear tests are performed to simulate the rotation in the principal stress direction induced by ocean wave. The tests include the cyclic preloading tests and liquefaction tests in the second loading on saturated loose sand with a relative density of 30%. The all tests are consolidated under isotropic condition. The effect of the cyclic preloading on the resistance to liquefaction of saturated loose sands under the condition of continuous rotation in the principal stress direction is investigated. Experimental data indicate that the void ratio of saturated sands has a negligible reduction after cyclic preloading. With the increase of the intensity of cyclic preloading (in the amplitude and in the number of cycles), the resistance to liquefaction in the second loading is increased continuously under the condition that the liquefaction does not occur during the cyclic preloading. The reason is that the construction of more stable structure due to the uniformity of the void and the better interlocking of the particles when the cyclic preloading is applied to the saturated sand.展开更多
基金The National Natural Science Foundation of China(No.51575304)the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2012ZX04012011)
文摘In order to investigate the sand mold strength after the aeration sand filling-high pressure squeeze moldingprocess,a tree-dimentional(3D)numerical simulation was introduced.The commercial finite element method(FEM)software ABAQUScombined with a revised Drucker-Prager/Cap model was used to simulate the squeeze compaction process.Additionally,the sand bulk density after the aeration sand filling process was tested by a specially designed experiment,which divided the whole sand bulk in the molding chamber into5x9regions and it was used as the input to simulate the squeeze process.During the simulation process,the uniform modeling simulation and the patition modeling simulation methods were used a d the3D numercal simulation results were compared with correlative benchmark testings.From the3D numerica simulation results,it can be concluded that the uniform sand bulk density distribution can obtain a high quality sandmold and the revised Drncker-Pager/Cap model is suitable for handling the situation with the complex paaern.The3D numerical simulation results can predict well the sand mold strength distribution and can be used as guidelines for the production practice.
文摘In this paper, a study of sandy soil compaction with different granulometry and moisture content has been performed, and soil mechanical property variations in moisture and granulometry have been investigated. Investigations were performed to compare hydrostatic compression test （HCT） responses and evaluate the compression index, Cc, which is an indicator of the soil＇s susceptibility to compaction-induced damage. The experiments have been performed on 24 soil samples typologies. Each sample has been obtained by combining three types of soil granulometry （types A, B and C） with a relative content varying from 0% to 100% in 20% increments. Soil type A had a granulometry ranging between 0.5 mm and 1 mm, type B between 0.25 mm and 0.5 mm, and type C less than 0.25 mm. These samples were representative of a sandy soil, chemically inactive and had various granulometries and initial moisture contents. A cell for HCT has been set up to allow the initial volume measurement of the test pieces and the subsequent changes during HCT with an estimated error less than 0.1 cm3. All samples were pre-compacted and prepared in agreement with the actual standards. The experimental data are reported in diagrams, the data allowed comparison of the mechanical behaviors between the considered unsaturated soils and underlined how soil moisture and granulometry affect soil response during HCT. Furthermore, because of the methodology used, the equipment was very economical.
基金the National Natural Science Foundation of China (Nos. 50579006 and 50639010)
文摘By using the soil static and dynamic universal triaxial and torsional shear apparatus, a series of combined cyclic shear tests are performed to simulate the rotation in the principal stress direction induced by ocean wave. The tests include the cyclic preloading tests and liquefaction tests in the second loading on saturated loose sand with a relative density of 30%. The all tests are consolidated under isotropic condition. The effect of the cyclic preloading on the resistance to liquefaction of saturated loose sands under the condition of continuous rotation in the principal stress direction is investigated. Experimental data indicate that the void ratio of saturated sands has a negligible reduction after cyclic preloading. With the increase of the intensity of cyclic preloading (in the amplitude and in the number of cycles), the resistance to liquefaction in the second loading is increased continuously under the condition that the liquefaction does not occur during the cyclic preloading. The reason is that the construction of more stable structure due to the uniformity of the void and the better interlocking of the particles when the cyclic preloading is applied to the saturated sand.
