双排桩加固滑坡地段隧道衬砌地震累积变形效应试验研究

Experimental study on the seismic cumulative deformation effect of tunnel lining in landslide area reinforced by double-row piles

为研究双排桩加固滑坡地段隧道衬砌的地震累积变形效应(SCDE),以实际工程案例为依托首次开展振动台试验,测试得到不同概率水平地震作用下双排桩和隧道衬砌的加速度及动态位移响应数据信息。建立边坡灾变全过程中隧道衬砌受力变形-频率-能量演变特性的内在关联机制。提出一种反应地震波激励下隧道衬砌塑性变形程度的分析指标-塑性效应系数(PEC),并从能量传递特性角度利用Arias强度(I_(a))验证以PEC分析隧道衬砌塑性变形的适用性。基于快速傅里叶变换(FFT)方法,讨论地震波频率分量对隧道衬砌SCDE和局部变形的影响机制。结果表明,PEC充分考虑隧道衬砌的塑性变形特性,且物理意义明确,相比峰值隧道位移(PTD)能更加清晰反应隧道衬砌的塑性变形程度和SCDE。辅以I_(a)强度峰值比(M_(Ia))对比验证分析,系统揭示隧道衬砌的地震累积变形演化过程和质点空间位置区域性响应特征。频域分析结果表明,地震波的低频分量和高频分量分别对隧道衬砌的整体和局部变形起着控制性作用。双排桩加固滑坡地段隧道衬砌的动态变形响应是一个渐进性累计演化过程,清晰判识隧道衬砌的SCDE,可为确定其所处地震变形状态和适当的抗震加固提供科学依据。

In order to study the seismic cumulative deformation effect(SCDE)of tunnel lining in landslide area reinforced by double-row piles,the shaking table test is conducted for the first time based on an actual engineering case to test the acceleration and dynamic displacement response data of double-row piles and tunnel lining under different probability levels of seismic action.The internal correlation mechanism of the deformation-frequency-energy evolution characteristics of the tunnel lining during the whole process of slope disaster is established.An analysis index of plastic deformation degree of tunnel lining under seismic wave excitation-plastic effect coefficient(PEC)is proposed,and the applicability of PEC to analyze plastic deformation of tunnel lining is verified by Arias strength(I_(a))from the perspective of the energy transfer characteristics.Based on the fast Fourier transform(FFT)method,the influence mechanism of the seismic wave frequency components on SCDE and local deformation of the tunnel lining is discussed.The results show that PEC fully takes into account the plastic deformation characteristics of the tunnel lining and has a clear physical meaning,which can more clearly reflect the degree of plastic deformation and SCDE of the tunnel lining than the peak tunnel displacement(PTD).The seismic cumulative deformation evolution process of tunnel lining and the regional response characteristics of the particle spatial position are systematically revealed by the comparative verification analysis of I_(a)peak strength ratio(M_(Ia)).The results of the frequency domain analysis show that the low-frequency and high-frequency components of the seismic waves play a controlling role in the overall and local deformation of the tunnel lining,respectively.The dynamic deformation response of tunnel lining in the landslide area reinforced by double-row piles is a progressive cumulative evolution process.Obtaining a better understanding of the SCDE of the tunnel lining can provide a scientific basis for the identification of the seismic damage status and appropriate seismic reinforcement.