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通过数值模拟验证液化的隔振作用。在浅埋地下结构周围设置碎石排水层,应用FLAC3D作碎石排水层法抗液化数值模拟试验,分析不同碎石排水层方案的抗液化效果和液化场施加碎石排水层后地下结构的动力特性变化。计算结果表明,典型液化场中砂土达到液化状态,其加速度、速度、位移振幅马上衰减;砂土在液化状态变为流体,液化过程是砂土体积压应变不断积累增大的过程,液化后体积压应变积累不再增加,液化土有效应力和抗剪强度均为0,不能传递剪力,起隔离外界力的作用,液化场中结构的加速度反应也比非液化场或弹性场小。液化场中结构的存在降低了其周围的动水压力,结构阻障了周围土液化的产生。液化场中地下结构周围设置碎石排水层,结构周围则不会液化,远处液化场超静水压力显著降低,结构不出现上浮,结构下沉,水平漂移减小,内力增大。研究成果为地下结构穿越液化土层设计提供理论及试验基础。
The numerical simulation validates the vibration isolation effect of liquefaction. The gravel drainage layer was set up around the shallow underground structure. The FLAC3D was used to simulate the liquefaction of the gravel drainage layer. The liquefaction effect of the different gravel drainage layers and the dynamic of the subsurface structure after applying the gravel drainage layer were analyzed Changes in characteristics. The calculated results show that the sand liquefaction in a typical liquefaction field is liquefied and its acceleration, velocity and displacement amplitudes decay immediately. The sand becomes liquefied in the liquefied state, and the liquefaction process is the process of continuous accumulation of compressive strain in the sand. After liquefaction The accumulation of volumetric compressive strain no longer increases, and the effective stress and shear strength of liquefiable soil are both 0, which can not transfer shear force and isolate the external force. The acceleration response of the structure in liquefaction field is also smaller than non-liquefied field or elastic field. The existence of the structure in the liquefaction field reduces the hydrodynamic pressure around it and the structure obstructs the liquefaction of the surrounding soil. In the liquefaction field, the gravel drainage layer is arranged around the underground structure, the liquefaction will not occur around the structure, and the hydrostatic pressure in the liquefaction field will be significantly reduced in the distant place. The structure does not float upward, the structure sinks, the horizontal drift decreases, and the internal force increases. The research results provide theoretical and experimental basis for the design of underground structure crossing liquefied soil.