摘要
针对南海北部陆坡区地震成因的海底滑坡频发问题,采用室内模型分析法分析地震对于海底滑坡触发的影响作用。仿照南海北部陆坡海底工程环境构建水槽模型,分析引发海底斜坡失稳的临界地震参数,观察滑坡的运移特征,对比振动前后土体力学性质变化;并依据水槽模型构建有限元数学模型,计算模拟陆坡在不同地震加载下的稳定系数并进行对比。综合两部分试验结果发现:本次试验构建的模拟陆坡在自然条件下处于稳定状态,随着模拟地震的加载会逐渐发生失稳,表现为物模试验滑坡的发生以及数模稳定系数骤减至<1。失稳发生的临界地震条件为:振动频率2~3 Hz,振动加速度1.96 m·s^(-2)。在这一过程中,加速度的作用占主导地位。振动过后陆坡土体强度降低,抗剪强度下降,是陆坡失稳滑动的原因所在。地震波的荷载在斜坡中部的响应最为突出。
In view of the frequent submarine landslides caused by earthquakes on the northern continental slope of the South China Sea,indoor model analysis is applied to analyze the impact of earthquake on triggering the submarine landslide.According to the submarine engineering environmental conditions on the northern continental slope of the South China Sea,a flume model is constructed for analyzing the critical seismic parameters that cause the instability of the submarine slope,observing the migration characteristics of the landslides and comparing the changes of soil mechanical properties before and after the vibration.Based on the flume model,a finite element mathematical model is established for calculating and comparing the stability coefficients of the simulated slope under different seismic loads.It is found from the two tests that the simulated slope constructed in the present experiment is in a stable state under the natural conditions and becomes unstable gradually with the loading of the simulated earthquake,showing that the landslide occurs in the physical model test and the stability coefficient suddenly drops to<1 in the mathematical model test.The critical seismic conditions at which the slope becomes unstable are that the vibration frequency is 2~3Hz and the vibration acceleration is 1.96m·s^(-2),with the acceleration playing a leading role in this process.The decreases in soil strength and soil shear strength of the land slope after the vibration could be the reason for the slope instability and sliding.The response of the seismic wave load could be the most prominent at the middle of the slope.
作者
李佳林
冯秀丽
刘隆
LI Jia-lin;FENG Xiu-li;LIU Long(College of Marine Geosciences, Ocean University of China, Qingdao 266100, China;Second Institute of Oceanography, MNR, Hangzhou 310012, China)
出处
《海岸工程》
2021年第4期249-260,共12页
Coastal Engineering
基金
国家重点研发计划项目——ROV精准取样技术应用与南海北部深海沉积过程研究(2017YFC0306703)
国家自然科学基金项目——自升式平台桩靴基础的全工作周期稳定性分析(U1806230)。
关键词
海底滑坡
地震
物理模型
临界条件
强度折减法
稳定系数
submarine landslide
earthquake
physical model
critical condition
strength reduction
