摘要
降雨、地震作用下,隧道洞口边坡易产生严重破坏,有必要研究隧道洞口边坡及支挡结构的动力响应特性。以中国西南某隧道洞口边坡为例,通过振动台模型试验,分析降雨、地震作用下预应力锚索桩板墙加固隧道洞口边坡的动力响应与破坏模式。研究结果表明:(1)隧道洞口边坡破坏过程为坡顶张拉裂缝―坡脚剪切溃裂―边坡整体滑移破坏。由于雨水入渗,坡表土体在地震作用下易产生局部浅层破坏。边坡破坏模式为张拉-剪切型。(2)随峰值加速度增加,桩身PGA放大系数显著增大,应重视该类支护结构在地震作用下的惯性放大效应。(3)桩后峰值土压力随峰值加速度增加而增大,由“S型”分布逐渐转变为倒三角形分布。峰值加速度大于0.4g时,锚索轴力逐渐增加,充分发挥张拉作用。(4)桩土压力与加速度傅里叶谱幅值集中于低频段,地震波沿高程传播存在“高频滤波效应”。(5)桩身位移谱幅值随峰值加速度增加而逐渐增大,沿桩身向上呈增加趋势;位移谱主频分布于1~4 Hz,卓越频率为2.5 Hz,与地震荷载的主频较接近。(6)桩体加速度间的关联性较好,桩体加速度、动土压力、桩体应变、锚索轴力相关性随输入峰值加速度增加而逐渐降低。
The tunnel slope is prone to be damaged under the action of earthquakes and rainfall.It is necessary to study the dynamic response characteristics of the reinforcement structure of the tunnel portal slope.A tunnel portal slope in southwest China is experimentally studied as an example.The dynamic response and failure mode of the tunnel portal slope reinforced by prestressed anchor sheet-pile wall under earthquakes and rainfall are analyzed through shaking table test.The main conclusions include:(1)The failure process of the slope can be summarized as:tension cracks at the slope crest-shear cracks shear cracking,the foot of the slope,and overall sliding failure of the slope.Under the seismic action,the local damage occurs easily near the slope surface due to the infiltration of rainfall.The failure mode is tension-shear.(2)The peak acceleration amplification factors along the pile shaft increase significantly with the increase of peak acceleration,thus the inertial amplification effect of the structure should be considered properly.(3)The peak earth pressures behind the pile increase as the input peak acceleration becomes larger and the earth pressure changes from the S-shaped distribution to the inverted triangle distribution.When the peak acceleration is greater than 0.4 g,the axial force of anchor cable increases gradually and the tension effect is fully exerted.(4)The amplitude of Fourier spectrum of soil pressure and acceleration of pile are concentrated in the low frequency band.There is a high-frequency filtering effect of seismic wave propagation along the elevation.(5)The displacement spectrum amplitude of the pile increases as the peak acceleration becomes greater and increases larger along the pile height.The main frequency of the displacement spectrum is 1–4 Hz and the dominant frequency is 2.5 Hz,which is close to the dominant frequency of the seismic load.(6)The correlation between pile accelerations is well related and the correlations of pile acceleration,dynamic soil pressure,strain and axial force of anchor cable decrease with the increase of peak acceleration.
作者
冯海洲
蒋关鲁
何梓雷
郭玉丰
胡金山
李杰
袁胜洋
FENG Hai-zhou;JIANG Guan-lu;HE Zi-lei;GUO Yu-feng;HU Jin-shan;LI Jie;YUAN Sheng-yang(Key Laboratory of High-Speed Railway Engineering,Ministry of Education,Southwest Jiaotong University,Chengdu,Sichuan 610106,China;School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031;China Railway First Survey and Design Institute Group Co.,Ltd,Xi’an,Shaanxi 710043,China;China Railway 18TH Bureau Group Corporation Limited,Tianjin,30022,China)
出处
《岩土力学》
EI
CAS
CSCD
北大核心
2023年第S01期50-62,共13页
Rock and Soil Mechanics
基金
国家自然科学基金资助项目(No.51878577)
基于性能设计的高速铁路新型加筋土挡墙服役行为演化与控制研究(No.2022YFE0104600)
关键词
预应力锚索桩板墙
隧道洞口边坡
降雨、地震
动力响应
振动台试验
prestressed anchor sheet pile
tunnel portal slope
earthquake and rainfall
dynamic response
shaking table test
