沉管隧道周围砂质海床波致液化进程研究  

Wave-induced Progressive Liquefaction Around Immersed Tunnel in Sandy Seabed

作　　者：张浩文 熊浩 ZHANG Haowen;XIONG Hao(JSTI Group,Nanjing,Jiangsu 210017,China)

机构地区：[1]苏交科集团股份有限公司,江苏南京210017

出　　处：《水利与建筑工程学报》2018年第6期207-211,224,共6页Journal of Water Resources and Architectural Engineering

摘　　要：考虑土骨架-孔隙流体两相介质动力耦合效应,采用由Masing法则构造的Davidenkov本构模型描述土骨架的非线性滞回特性;在FLAC^(3D)中将Byrne提出的循环荷载作用下土体塑性体积应变增量公式引入到Biot动力固结方程中用以描述海床累积孔压的增长和液化进程。建立可液化海床-沉管非线性动力相互作用二维分析模型,分析结果表明:土的非线性对波浪作用下沉管-海床系统的动力响应有重要影响。沉管周围海床的渐进液化特征不同于远场,远场海床液化仅沿深度发展,呈一维特征。近场海床的液化首先发生在沉管的顶部和底部,随后液化区域沿沉管周边发展,呈明显的二维特征;埋置于海床中的沉管结构改变了海床内的初始应力状态,波浪作用下沉管和海床之间的相互作用导致近场海床产生复杂的应力路径。因此沉管周围海床的循环剪应力比Ccssr明显大于远场海床,较好地解释了沉管周围海床不同于远场的渐进液化特征。A better understanding of the wave-seabed structure interactions is essential for the evaluation of the stability of the seabed foundation under dynamic loading in the ocean environments.In this study,based on Biot's partly dynamic poroelastic theory in FLAC3D,a viscoelastic constitutive model in terms of Davidenkov backbone curve was used to describe nonlinear stress-strain hysteresis characteristic of the seabed soil.The pore pressure increasing pattern is modeled by Byrne pore pressure increment model,which was introduced as the wave-induced residual pore pressure source term,and implanted into Biot dynamic consolidation equation.Then,an effective stress analysis framework was established and used to analyze the dynamic response of a shallow buried immersed tunnel.The results indicate the progressive liquefaction of the soil around the segment showing obvious two-dimensional characteristics compared with the far field where the liquefaction area developing just underside;Due to the stress state modified by the placement of segment,wave propagation induce complex stress path in the seabed around the segment,which result in the large CSSR in the seabed around the segment.The result effectively explain the different progressive liquefaction characteristics near and far from the segment.

关 键 词：非线性海床 沉管隧道 累积液化 Boit动力固结方程 循环剪应力 

分 类 号：TU443[建筑科学—岩土工程]