摘要
黄土山岭地区的隧道开挖破坏了原有边坡内部的平衡状态。在地震动荷载作用下,隧道洞口段及边坡都可能受到严重破坏,也会反映出不同的动力特性和变形特征。首先通过大型振动台对边坡坡度为60°坡脚进洞工况进行试验,然后利用Midas-GTS有限元软件对边坡坡度为60°不同高程进洞的工况进行了数值模拟分析。结果表明:坡顶加速度随着进洞高程的增大而增大,同种波形和输入方向,输入峰值加速度增大,加速度放大效应减小,出现放大效应趋于饱和现象;隧道洞口段最大主应力先增大后减小,仰拱大于拱顶,一般在距洞口15 m达到峰值,50 m后趋于平稳;试验中坡顶出现拉剪破坏,隧道衬砌与上部土体自振频率不同导致的错动形成竖向裂缝,两侧坡脚处出现横向裂缝且发展速度较快,坡面整体发生破坏,震陷滑塌现象很明显且大块土体整体滑落,有隧道一侧滑塌破坏程度大于纯边坡一侧;应力最大值断面距洞口42 cm,是2.33倍的隧道最大跨径,最大加速度多出现在距洞口约3.89~4.06倍隧道跨径处;由于临空面的存在,洞口段具有明显的动力放大效应,各监测点位移都有一个略微增大再减小的过程,最大值出现在距洞口60 m处,因此大断面黄土隧道的抗震设防长度取5倍隧道洞径较为合适;相较于振动台试验,数值模拟数结果偏大,但是可以较好地反映出加速度和土压力的基本变化规律。
The tunnel excavation in the loess mountain area destroyed the original slope internal balance.Under the action of earthquake dynamic load,the tunnel entrance and the slope may be seriously damaged and it also reflects different dynamic characteristics and deformation characteristics. First,the large-scale platform vibrator test under the condition of 60° slope foot gradient at tunnel portal is conducted. Then,the working conditions of 60° slope gradient with different tunnel portal elevations are performed by using MidasGTS FE software. The result shows that（1） The acceleration at top of the slops increases with the increase of the tunnel portal elevation. With the same waveform and input direction,the input peak acceleration increases,the acceleration amplification effect decreases,and the amplification effect tends to saturation.（2） The maximum principal stress at the tunnel portal increased firstly and then decreased,and the value at the inverted arch is larger than that at the vault,the maximum principal stress generally reached the peak at15 m from the portal,and tended stable after 50 m.（3） The slope top appeared tensile shear failure in the test. The tunnel lining and the upper soil shaped dislocation and vertical crack due to the different naturalfrequencies. At both sides of the slope foot appeared transverse cracks and the propagation speeds are fast,the whole slope is damaged,the collapse of the seismic subsidence is obvious,the hunk soil is slipping as a whole. The damage of tunnel side is greater than that of the pure slope side.（4） The maximum stress section is 42 cm from the portal,which is 2. 33 times the maximum tunnel span. The maximum acceleration occurred at about 3. 89-4. 06 times the tunnel span of portal.（5） Due to the existence of the free surface,the portal section has obvious dynamic amplification effect,the displacement at each monitoring point has a process of slightly increasing and then decreasing,the maximum value appeared at 60 m from the portal,so the approp
作者
梁庆国
边磊
张钦鹏
黄俊
王猛
LIANG Qing-guo;BIAN Lei;ZHANG Qin-peng;HUANG Jun;WANG Meng(National Demonstration Center for Experimental Civil Engineering Education, Lanzhou Jiaotong University, Lanzhou Gansu 730070, China;Gansu Provincial Key Laboratory of Road ＆ Bridge ＆ Underground Engineering, Lanzhou Gansu 730070, China)
出处
《公路交通科技》
CAS
CSCD
北大核心
2018年第7期65-76,共12页
Journal of Highway and Transportation Research and Development
基金
国家自然科学基金项目(41262010
41562013)
兰州交通大学百名青年优秀人才培养计划项目(2017150)
关键词
隧道工程
地震动力特性
振动台试验
数值模拟
隧道边坡
动力响应加速度
tunnel engineering
seismic dynamic characteristics
vibration platform test
numericalsimulation
tunnel side slope
dynamic response acceleration
