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

据报道，液化地面根据地球物理条件以几米的幅度移动，对地基桩和埋地管道等地下结构造成致命损害。这些液化引起的地面移动已被地震工程界公认为结构抗震设计的关键因素之一。为了弄清液化引起的地面移动对地下结构的影响，作者在振动台上进行了模型地面试验研究。采用正弦激励，对长6.0m、深1.0m、宽1.0m的模型饱和砂土地基进行了液化试验。模型地埋设了直径为1.8 cm和2.2 cm的丙烯和乙烯基管桩模型。通过对模型桩地基的加速度、位移、孔压、土压力和模型桩地层的测试，发现模型桩在地基位移达到最大值时，其应变不一定最大，这说明通过地弹簧作用于地下结构物的“地震反应位移法”不适用于液化土地基中的结构物。通过对试验结果的详细分析，得出了液化土侧向运动对地下结构的地震荷载与液流阻力相似的结论。

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.