In order to investigate the influence of the vertical vibration loading on the liquefaction of saturated sand,one dimensional model for the saturated sand with a vertical vibration is presented based on the two phase ...In order to investigate the influence of the vertical vibration loading on the liquefaction of saturated sand,one dimensional model for the saturated sand with a vertical vibration is presented based on the two phase continuous media theory.The development of the liquefaction and the lique- faction region are analyzed.It is shown that the vertical vibration loading could induce liquefaction. The rate of the liquefaction increases with the increase of the initial limit strain or initial porosity or amplitude and frequency of loading,and increases with the decrease of the permeability or initial modulus.It is shown also that there is a phase lag in the sand column.When the sand permeability distribution is non-uniform,the pore pressure and the strain will rise sharply where the permeability is the smallest,and fracture might be induced.With the development of liquefaction,the strength of the soil foundation becomes smaller and smaller.In the limiting case,landslides or debris flows could occur.展开更多
It has been reported([1]) that when a loosely packed column of saturated sand in a vertical cylindrical container is shock loaded axially by dropping to the floor, large horizontal cracks initiate, grow and eventually...It has been reported([1]) that when a loosely packed column of saturated sand in a vertical cylindrical container is shock loaded axially by dropping to the floor, large horizontal cracks initiate, grow and eventually fade away in the sand as it settles under gravity. This paper shows that a similar phenomenon can also be observed when shock loading is replaced by forcing water to percolate upward through the sand column. It is believed that our result sheds further light on the physics of formation of these cracks.展开更多
The liquefaction of loess under dynamic loading is studied experimentally with a dynamic triaxial test system. The effects of over-consolidation ratio (OCR), saturation degree and the frequency of dynamic loading upon...The liquefaction of loess under dynamic loading is studied experimentally with a dynamic triaxial test system. The effects of over-consolidation ratio (OCR), saturation degree and the frequency of dynamic loading upon loess liquefaction are investigated. The development of pore pressure within loess samples is also discussed. Based on the experimental results, the empirical relationship between pore pressure ratio and loading cycle number ratio is established for normal consolidated saturated loess.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 project supported by the National Natural Science Foundation of China(40025103,10202024)
文摘In order to investigate the influence of the vertical vibration loading on the liquefaction of saturated sand,one dimensional model for the saturated sand with a vertical vibration is presented based on the two phase continuous media theory.The development of the liquefaction and the lique- faction region are analyzed.It is shown that the vertical vibration loading could induce liquefaction. The rate of the liquefaction increases with the increase of the initial limit strain or initial porosity or amplitude and frequency of loading,and increases with the decrease of the permeability or initial modulus.It is shown also that there is a phase lag in the sand column.When the sand permeability distribution is non-uniform,the pore pressure and the strain will rise sharply where the permeability is the smallest,and fracture might be induced.With the development of liquefaction,the strength of the soil foundation becomes smaller and smaller.In the limiting case,landslides or debris flows could occur.
基金The project supported by the National Natural Science Foundation of China(19832010)by the Chinese Academy of Sciences(KJ952-S1-202)
文摘It has been reported([1]) that when a loosely packed column of saturated sand in a vertical cylindrical container is shock loaded axially by dropping to the floor, large horizontal cracks initiate, grow and eventually fade away in the sand as it settles under gravity. This paper shows that a similar phenomenon can also be observed when shock loading is replaced by forcing water to percolate upward through the sand column. It is believed that our result sheds further light on the physics of formation of these cracks.
基金The project supported by the National Natural Science Foundation of China(50178005)
文摘The liquefaction of loess under dynamic loading is studied experimentally with a dynamic triaxial test system. The effects of over-consolidation ratio (OCR), saturation degree and the frequency of dynamic loading upon loess liquefaction are investigated. The development of pore pressure within loess samples is also discussed. Based on the experimental results, the empirical relationship between pore pressure ratio and loading cycle number ratio is established for normal consolidated saturated loess.
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.
