地震荷载下危岩运动特征的模拟研究  

A STUDY ON MOTION CHARACTERISTICS OF ROCKFALL UNDER SEISMIC LOADINGS BY DDA

作　　者：周月智 刘红岩[2] 李俊峰 祁小博[3] 陈红旗[3] ZHOU Yuezhi;LIU Hongyan;LI Junfeng;QI Xiaobo;CHEN Hongqi(CCCC First Harbor Consultants Co.,Ltd.,Tianjin 300222,China;College of Engineering&Technology,China University of Geosciences(Beijing),Beijing 100083,China;China Institute for Geo-Environmental Monitoring,Beijing 100081,China)

机构地区：[1]中交第一航务工程勘察设计院有限公司,天津300222 [2]中国地质大学(北京)工程技术学院,北京100083 [3]中国地质环境监测院,北京100081

出　　处：《工程地质学报》2021年第5期1387-1400,共14页Journal of Engineering Geology

基　　金：国家重点研发计划(资助号:2017YFC1501005,2019YFC1509701)。

摘　　要：西南地区地形复杂,位于地震高发区域。为了进一步研究该区域地震作用下落石的运动特征,以我国九寨沟景区内荷叶寨后山危岩带2为例。首先研究危岩带2中单一危岩体在自重荷载下的失稳情况,分别采用Roc Fall和非连续变形分析方法(DDA)进行模拟,结果表明:DDA和Roc Fall的模拟结果相近。DDA中落石水平位移模拟结果为210.6 m,Roc Fall中大部分落石水平位移分布在205 m附近。鉴于Roc Fall的局限性,采用DDA方法继续研究地震作用下危岩体的密度、高度、体积和地震波峰值加速度等因素对落石运动特征如运动轨迹、水平位移和速度的影响规律,并监测落石在坡脚附近的最大弹跳高度。研究结果表明:(1)危岩带2所处边坡自然坡角范围为65°~75°,落石在坡面上加速,在高程约2292 m(与居民区相对高差约为132 m)处发生抛射,运动方式以滚动、碰撞、弹跳为主;(2)岩体软弱结构面的贯通时间随落石密度、体积以及地震波峰值加速度增大而减小;(3)峰值速度随边坡高度、体积及地震波峰值加速度增大而增大;(4)水平位移随落石密度、边坡高度及地震波峰值加速度增大而增大;(5)坡脚处落石最大弹跳高度随各因素变量增大而增大。继续研究内部存在节理裂隙的岩体(3条平行节理将危岩分为K1~K4部分)在地震荷载下的运动特征:(1)在地震荷载作用下,危岩沿节理面发生倾倒破坏,落石水平位移模拟结果为191.5~243.8 m;(2)落石在坡脚附近的最大弹跳高度范围为0~13.8 m。In order to research the failure of rock mass induced by earthquakes,we took the rock avalanche at Heyezhai,Sichuan,China as the research object.Firstly,we simulated the failure under self-weight by DDA and RocFall codes.The results show RocFall and DDA could coincide with each other well.Then we simulated the failure of the single rock under seismic loading with the influence of density,height,size and peak acceleration of horizontal simple harmonic waves.Finally,we simulated the failure of the rock with a set of parallel joints.In the simulation,we monitored some important parameters such as trajectories,horizontal displacement,velocity and the maximum bounce height at the slope foot.The simulation results show the follows.(1)The natural slope angle of rock zone 2 is at 65°~75°,the rockfall accelerated on the slope surface and then ejected at the height of about132 m.The main motion modes are rolling,collision and bouncing.(2)The breakthrough time of weak structural plane decreases with increasing of the density,volume and peak acceleration of seismic waves.(3)The peak velocity increases with increasing of slope height,volume and peak acceleration of seismic waves.(4)The horizontal displacement increases with increasing of the density,slope height and peak acceleration of seismic waves.(5)The maximum jumping height of rockfall at the foot of slope is positively correlated with various factors.We continued to study the failure of rock mass with internal joints under seismic loading:(1)The horizontal displacement range of rockfall is 191.5~243.8 m.(2)The maximum bounce height at the slope foot was 13.8 m.

关 键 词：落石 运动特征 地震荷载 非连续变形分析方法(DDA) 

分 类 号：P642.21[天文地球—工程地质学]