Abstract
Based on the longitudinal and transverse seismic and shock absorption theory of tunnel structure, relying on the actual engineering, a finite element analysis model of a typical mountain tunnel was established. Four calculation conditions including the presence or absence of shock absorption layers and seismic joints are defined. The principal tensile (compressive) stress and displacement response of the vault, arch waist, foot of side wall, and middle of invert are studied. The results show that the shock absorption layer and the seismic joint have great influence on the dynamic response of the tunnel structure, which can reduce the main tensile (pressure) stress of different parts of the lining and change the way of stress distribution. The peak principal tensile (pressure) stress of the lining is reduced more obviously when the shock absorption layer and seismic joint are set. However, the presence of the shock absorption layer and the seismic joint will increase the peak displacement of each monitoring point of lining. The displacement of each monitoring point of lining is increased more obviously by the single shock absorption layer. Therefore, when the seismic design of the tunnel structure is carried out, the maximum seismic demand of the tunnel structure should be determined according to the specific calculation content in order to guide the design.
Highlights
Four calculation models are established for the mountain tunnel structure with or without shock absorption layer and seismic joints, and the seismic research is carried out to obtain the following conclusions: (1) Whether it is a single shock absorption layer, a single seismic joint, or both, the maximum internal force on the same cross section can be greatly reduced in the vault, arch waist, foot of side wall, and middle of invert, and the internal force on the same cross section is more uniform
(2) With the increase of the distance from the monitoring section to the tunnel entrance, the principal tensile stress on the vault, arch waist, foot of side wall, and middle of invert decreases first and tends to be stable when there is no damping layer and seismic joint. erefore, we can use the change of stress to judge the weak area of the tunnel portal section, and determine the fortification length of the tunnel portal section
(3) When the shock absorption layer and seismic joint are set at the same time, the effect of reducing the peak principal tensile stress on the lining is more obvious
Summary
Frequent earthquakes, especially strong earthquakes, are easy to cause landslides and collapses to block the tunnel portal, and often lead to deformation of the tunnel lining, cracks of tunnel portal, and other earthquake damage [1,2,3]. erefore, it is very important to study the dynamic response laws, seismic and shock absorption measures, and seismic safety evaluation of the tunnel structure in the high-intensity earthquake areas [4,5,6]. Erefore, it is very important to study the dynamic response laws, seismic and shock absorption measures, and seismic safety evaluation of the tunnel structure in the high-intensity earthquake areas [4,5,6]. E effect of this method has been verified by theoretical analysis and model tests, which are mainly achieved by changing the performance of the tunnel structure itself or by setting a shock absorption device between the underground structure and the stratum [10,11,12]. Wang et al [13] proved that the dynamic strain amplitude of the lining and the cracks of lining were reduced after the shock absorption layer was set by the analytical solution and the experiment. Advances in Civil Engineering strong earthquake. e research in this paper is expected to provide the relevant theoretical basis for the seismic and shock absorption research of the tunnel structure and provide a certain reference for similar projects
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