| dc.description.abstract | In the past, people′s lives and property have been threatened by soil liquefaction caused by siginificant earthquakes around the world. Such as large area ground surface settlement, toppling of buildings, slope displacement. Soil liquefaction is easily happened in saturated sand layer, especially in the region of erathquake. For example, niigata earthquake happened in 1964 in Japan and accompanied by large area soil liquefaction. Make a lot of upper structure of dumping disasters occur, which leads to be more of international scholars in the soil liquefaction caused by related issues.
This project was conduct experiments of soil liquefaction and lateral spreading by National Central University geotechnical centrifuge and shaking table. A variety of sensors were embedded in the centrifuge model, such as vertical displacement transducers to observe soil displacement, reduce scale cone penetration test to compare resistance before and after liquefaction, accelerometers, pore water pressure transducers and markers to observe soil response under 26 times of artificial gravity field. This study will compare to different pore ratios of the same relative density and the same pore ratio but different particle sizes on a 5 degree slope. The results of LEAP2017 test to verify the difference of liquefaction behavior during earthquakes.
The test results show that : (1) In the same high liquefaction region, the same pore ratio and different relative densities have indirect differences in liquefaction depth. (2) Under the same relative density, soil with large pores will be easier to liquefy; under the same pore ratio, the looser relative density will reach liquefaction quickly. (3) the initial effective stress of surface soil is small, so it is easy to achieve soil liquefaction behavior. However, due to the relationship of slope, the thickness of soil layer and the size of pore ratio also affect the dissipation rate of excess pore water pressure. (2) As the soil layer collapses due to liquefaction, the displacement direction of the surface were all shifted to the lower part of the slope. The displacement was proportional to the liquefaction depth. However, due to the influence of the coriolis force, the displacement in the strike direction will deviate from the direction of vibration. (3) After liquefaction, lateral displacement of soil layer occurs due to lateral collapse. The amount of lateral collapse is proportional to the liquefaction depth, and decreases with the deeper the depth. Lateral movement stopped after a certain depth under the surface. (4) The impedance of the cone tip increases with the increase of penetration depth, and the variation of the impedance after the earthquake also increases.
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