Study on Liquefaction-Induced Ground Movement and Damage to In-ground Structures

据报告，液化的地面根据地球物理条件移动了几米，对地基桩和埋管等地下结构造成了致命的破坏。为了弄清地震作用引起的地面运动对地下结构的影响，在振动台上进行了模型地面试验研究。对长6.0m、深宽1.0m的饱和砂土地基模型进行正弦激励液化试验。模型桩分别为直径为1.8cm和2.2cm的亚克力管和乙烯基管。通过对模型桩周围地面加速度、位移、孔隙水压力、液化土土压力和地层压力的测试，发现当地面位移达到最大值时，模型桩的应变并不一定达到最大值，这就提出了所谓的“地震反应位移法”，其中地面位移被迫在-地面结构通过地面弹簧，不能应用于液化土中的结构。通过对实测结果的详细分析，得出液化土侧向运动对地下结构的地震荷载与液化土流动的拖曳力相似的结论。

It was reported that liquefied ground had moved with a magnitude of several meters depending on geophysical conditions and caused fatal damage to in-ground structures such as foundation piles and buried pipes. These liquefaction-induced ground movement has been recognized in earthquake engineering circles as one of critical factors for the earthquake resistant design of the structures.In order to clarify the effect of the liquefaction-induced ground movement on the in-ground structures, the authors conducted experimental studies by model ground on a shaking table. Model saturated sand ground of 6.0m in length and 1.0m in depth and width was liquefied by sinusoidal excitation. Pile models which is acryl and vinyl pipes with a diameter of 1.8cm and 2.2cm were buried in the model ground. The acceleration and displacement of the ground, pore water pressure, earth pressure of liquefied soil and the stratum the model piles were measured.From this experiment it was found that the strain of the model piles was not necessarily maximum when the ground displacement reached the maximum value, which suggests the so-called "Seismic Response Displacement Method" where the ground displacement is forced to in-ground structures through the ground spring, can not be applied to the structures in liquefied soil. Based on the detailed examination of the measured results the authors reached a conclusion that the seismic loading to in-ground structure from the lateral movement of liquefied soil is similar with the drag force of the liquid flow.