Study On The Absorb Characteristic Of Vibration Energy And Properties Modification For The Silty In Yellow River Estuary

The silty in Yellow River Estuary is transitional form with special project properties between sandy soil and clay. The dynamic responses of silty under different cyclic loading is very complex. It's very easy to have the liquefied destruction under wave and earthquake, and the harm is extremely serious. Based on the characteristic of sea bed in Yellow River Estuary, following the impact vibration tests and numerical analysis, the absorb characteristic and mechanism of vibration energy for the silty under cyclic loading in Yellow River Estuary is studied. The mainly work of this paper includes: (1) In-situ simulation experiments:Impact vibration tests are carried out in a typical area of the Yellow River estuary. Seismic detectors, electrodes and pore water pressure probes are laid at different depths in the silty, and dynamic responses of the soil are measured during the course of vibration to study the characteristics of vibration energy absorbed by the soil. And their influencing factors and mechanism are analyzed with data of electric resistivity,pore water pressure and strength of the soil. (2) Numerical simulation: Use plaxis finite element numerical analysis software and Mohr—Coulomb mathematics model to simulation the dynamic response of sea bed soil under cyclic loading. By analyzing the displacement and acceleration of soil pellet under the different vibration energy, study on the dynamic responses of sea bed soil and the absorb characteristic of vibration energy. And analyze their influencing factors and mechanism compared with the findings of in-situ simulation experiments.It is shown that:(1) In Yellow River Estuary, non-uniformity of dynamic responses of the silty increasing with the depth is obviously exhibited. The relatively obvious sensitive area of dynamic response and the relatively stable area can be seen from the analysis, the superficial weak interlayer responds more obviously to dynamic loads, and moreover, decreasing of energy mainly concentrates in the superficial layer above 60cm, especially in the middle layer about 40cm.(2)The non-uniformity of dynamic responses of the silty increasing with the time is also obviously exhibited. along with the increasing of vibration number, vibration energy absorbed by seabed soil will be redistributed and transferred, energy absorbed by surface layer(this depth is controlled by the energy of vibration load, and it is 0.4m in this experiment) will decrease while energy absorbed by middle and lower layers will increase. This change tendency mainly occurs in the Initial period of vibration, and it is slowly in the later period.(3)There are unique characteristic of dynamic responses for the silty under different vibration and tide level. It is because that the change tendency of soil nature is different under different external condition, and then make the absorb characteristic of vibration energy to be different.(4)By analyzing the change tendency of electric resistivity, pore water pressure and strength of the silty under cyclic loading in Yellow River Estuary, it is shown that: The relatively obvious sensitive area of electric resistivity is very same with the the relatively obvious sensitive area of energy absorb. By analyzing the pore water pressure and strength of the soil, we can explain the absorb characteristic of vibration energy for the silty very well. There are homologous relationships between the process of absorption of vibration energy by seabed soil and the variation processes of bulk resistivity, pore water pressure and strength of the soil. The absorb process and development tendency is the intrinsic factor for the unique response rule of electric resistivity,pore water pressure and strength of the soil.(5)By numerical simulation, it is shown that using finite element numerical analysis method and Mohr—Coulomb mathematics model to simulation the dynamic response of sea bed soil under cyclic loading in Yellow River estuary is feasible. The dynamic response of sea bed soil under cyclic loading is different between depth direction and horizontal direction. The change tendency of soil nature is influenced by the energy and frequency of cyclic loading, and then make the dynamic response of soil to be different.