地震作用下复合罐基变形特性研究

发布时间：2018-11-19 11:26

【摘要】：目前,我国石油化工工业迅速发展,大型储罐的使用日益增多,因此对地基处理的要求也越来越严格,其中复合地基是常用的软弱储罐地基处理方法之一。本文以复合地基为研究对象,利用FLAC3D软件,对地震作用下的天然地基、碎石桩复合地基以及CFG桩复合地基进行数值模拟,分析了不同地震振幅、不同附加荷载、不同桩体参数(桩径、桩长、桩体刚度)情况下地基的动力响应和变形特性,最后对多桩型复合地基进行了模拟,分析不同桩组合对复合地基动力特性的影响。论文所得主要结论如下:(1)在地震作用下,天然地基中的水平加速度自下而上被放大,土体动力变形的非线性表现得比较明显,孔隙水压力逐渐积累至峰值。随着输入地震加速度的减弱,动孔压基本稳定。竖向变形表现为地震初期下降较快,后期随着地震加速度的减小,竖向变形逐渐变缓,且出现不均匀沉降。地震结束后,初始沉降较快,随时间增长固结沉降逐渐变缓。(2)在地震作用下,单类型桩复合地基桩间土沉降量和水平加速度峰值均有所减小,CFG桩复合地基比碎石桩复合地基在沉降和加速度方面减小的要明显。单类型桩复合地基震后固结沉降明显减小,变化速率明显减缓,加固效果显著。(3)桩径、桩长、桩体刚度、附加荷载、地震振幅对单类型桩复合地基地震响应有一定的影响,其中,附加荷载和地震振幅的影响更为显著。(4)在地震作用下,随着CFG桩的加入,多桩型复合地基桩间土的沉降量逐渐减小,且随着CFG桩的增多,使得地基的整体强度有较大提高,其变形倾向于整体下沉。CFG桩与碎石桩的比例为5:4时,加固效果相对显著。
[Abstract]:At present, with the rapid development of petrochemical industry in China and the increasing use of large storage tanks, the requirements for foundation treatment are becoming more and more strict, among which the composite foundation is one of the commonly used soft tank foundation treatment methods. In this paper, the natural foundation, gravel pile composite foundation and CFG pile composite foundation under earthquake action are numerically simulated by using FLAC3D software, and the different seismic amplitude and additional load are analyzed. The dynamic response and deformation characteristics of the foundation under different pile parameters (pile diameter, pile length, pile stiffness) are analyzed. Finally, the effects of different pile combinations on the dynamic characteristics of composite foundation are simulated. The main conclusions are as follows: (1) under the earthquake, the horizontal acceleration in the natural foundation is enlarged from bottom to top, the nonlinear behavior of soil dynamic deformation is obvious, and the pore water pressure gradually accumulates to the peak value. With the weakening of the input seismic acceleration, the dynamic pore pressure is basically stable. The vertical deformation decreases rapidly at the beginning of the earthquake, and decreases gradually with the decrease of the seismic acceleration in the later period, and there is uneven settlement. After the earthquake, the initial settlement is faster, and the consolidation settlement becomes slower with the increase of time. (2) under the earthquake, the soil settlement and the peak value of horizontal acceleration of single pile composite foundation decrease. The decrease of settlement and acceleration of CFG pile composite foundation is more obvious than that of gravel pile composite foundation. The consolidation settlement of single type pile composite foundation is obviously reduced, the change rate is obviously slowed down, and the reinforcement effect is remarkable. (3) pile diameter, pile length, pile stiffness, additional load, The seismic amplitude has a certain influence on the seismic response of single type pile composite foundation, among which, the effect of additional load and seismic amplitude is more significant. (4) under earthquake action, with the addition of CFG pile, The settlement of soil between piles in multi-pile composite foundation decreases gradually, and with the increase of CFG pile, the overall strength of the foundation is greatly improved, and its deformation tends to sink as a whole. When the ratio of CFG pile to gravel pile is 5:4, The reinforcement effect is relatively remarkable.
【学位授予单位】：中国石油大学(华东)
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU433

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