scholarly journals Shaking Table Tests for Seismic Response of Oblique Overlapped Tunnel

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Hao Lei ◽  
Honggang Wu ◽  
Tianwen Lai
Keyword(s):  
Seismic Response ◽  
Cross Section ◽  
Slope Failure ◽  
Response Spectrum ◽  
Shaking Table ◽  
Dynamic Responses ◽  
Dynamic Strain ◽  
Seismic Load ◽  
Shaking Table Tests ◽  
The Cross

To study the dynamic response and spectrum characteristics of the three-dimensional crossing tunnel under the action of seismic load, we established a 1/50 downscale model based on a typical of the oblique overlapped tunnel and conducted a series of shaking table tests. Through examining the recorded dynamic responses (acceleration and dynamic strain measured at different locations in model tunnels), we found that the seismic response of the crown was the largest at the central section, and the invert of the tunnels was exactly opposite to the crown, which presented a “parabolic” distribution, and we inferred that the damage within the model may be mainly concentrated on the crown of the tunnels. Additionally, the dynamic strain showed obvious nonlinear and nonstationary characteristics under the action of different degrees of seismic intensities. Different from a single tunnel, the acceleration superposition effect appears in the cross section of two tunnels because of the spatial effect of overlapping tunnels, resulting in the obvious seismic response in the cross section. Meanwhile, we also found that the 1st dominant frequency (0.1–6.26 Hz) seismic wave played a leading role in the process of tunnel slope failure. Furthermore, the analysis of the acceleration response spectrum also showed that the surrounding rock mass has an amplification effect on low-frequency seismic waves. These results help us better understand the features of the dynamic responses and also provide evidence to reinforce the overlapped tunnels against earthquakes.

scholarly journals Dynamic Response of Parallel Overlapped Tunnel under Seismic Loading by Shaking Table Tests

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Tao Yang ◽  
Yunkang Rao ◽  
Honggang Wu ◽  
Junyun Zhang ◽  
Hao Lei ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Wavelet Packet ◽  
Failure Process ◽  
Side Wall ◽  
Shaking Table ◽  
Dynamic Responses ◽  
Dynamic Strain ◽  
Shaking Table Tests ◽  
Failure Characteristics ◽  
The Right

Potential earthquake-induced damage to overlapped tunnels probably occurs during the operation and maintenance of mountain tunnel engineering, especially in the seismically active zone. This study investigated the dynamic response and the failure characteristics of the parallel overlapped tunnel under seismic loadings by employing shaking table tests. The failure mode of the parallel overlapped tunnels was analyzed through macroscopic test phenomena. The dynamic responses of the surrounding rock and tunnel lining were evaluated by acceleration and dynamic strain, respectively. In particular, wavelet packets were used to investigate the spectrum characteristics of the tunnel structure in depth. The failure process of the model can be divided into three stages. The upper-span and the under-crossing tunnels showed different failure characteristics. Additionally, the lining damage on the outer surface of the tunnel mainly occurred on the right side arch waist and the left side wall, whereas the lining damage on the inner surface of the tunnel mainly appeared on the crown and invert. Wavelet packet energy results showed that the energy characteristic distributions of the upper-span and the under-crossing tunnels were not consistent. Specifically, the energy eigenvalues of the crown of the upper-span tunnel and the invert of the under-crossing tunnel were the largest, which should be considered to be the weak parts in the seismic design.

scholarly journals Seismic Response and Vibration Reduction Analysis of Suspended Structure under Wave Passage Excitation

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Wenhua Cai ◽  
Bujun Yu ◽  
Fajong Wu ◽  
Jianhua Shao
Keyword(s):  
Seismic Response ◽  
Wave Velocity ◽  
Vibration Reduction ◽  
Shaking Table ◽  
Dynamic Responses ◽  
Uniform Motion ◽  
Acceleration Response ◽  
Maximum Acceleration ◽  
Damping Effect ◽  
Suspended Structure

In order to study the influence of traveling wave effect on the seismic response and damping effect of suspended structure, a series of shaking table tests of the 1 : 20 suspended structure have been carried out to compare and analyze the dynamic responses of suspended structures under two points and a consistent input. The vibration damping effect and vibration reduction law of suspended structure are discussed at different apparent wave velocity and in the different connection. The research shows that the damping suspended structure has a good damping effect, and the amplitude reduction of the top displacement peak response is up to 15%, which corresponds to smaller apparent velocities. Moreover, the upper bound of the maximum acceleration response at the structures’ top under nonuniform input motions equals that of the uniform motion. However, there is a hysteresis in the acceleration response under wave travelling excitations, and the smaller the apparent wave velocity, the more obvious the hysteresis.

scholarly journals Investigation of Stochastic Seismic Response and Index Correlation of an Arch Dam Using Endurance Time Analysis Method

2020 ◽  
Vol 2020 ◽  
pp. 1-23
Author(s):  
Qiang Xu ◽  
Shutong Xu ◽  
Jianyun Chen ◽  
Jing Li
Keyword(s):  
Seismic Response ◽  
Failure Modes ◽  
Response Spectrum ◽  
Volume Ratio ◽  
Arch Dam ◽  
Dynamic Responses ◽  
Rock Foundation ◽  
Time Analysis ◽  
Endurance Time ◽  
Joint Opening

The seismic dynamic response and correlation between various indicators of an arch dam under a series of stochastic earthquake excitation are analysed. Seismic response assessment of a concrete arch dam is conducted through nonlinear endurance time analysis (ETA) of a typical arch dam. The 289 m high Baihetan arch dam in Southwest China (as a case study) is subjected to a set of 10 three-component endurance time acceleration histories (ETAHs) synthesised on the basis of the design site acceleration response spectrum to increasing peak ground acceleration (PGA). The effects of dam-reservoir-foundation interaction, radiation damping of infinite rock foundation, and nonlinearities of dam material and joint contact elements are considered. The indices to failure modes of damage propagation through the dam body and the deformation and joint opening beyond the limit states of the arch dam are identified. Dynamic responses, including deformation, joint opening, and damage distribution, are statistically analysed. The dispersion and correlation of indicators are analysed by employing the coefficient of variation and coefficient of correlation, respectively. The deterministic relationships between contraction joint opening, displacement, and damage volume ratio are obtained by using a multivariate fitting method. The results show that those failure indices have similar exponential trends, and seismic intensity parameters exert a significant influence on seismic response and damage under increasing PGA. The results of correlation and fragility analysis demonstrate that damage volume ratio and the sum of joint opening are consistent, which can provide a strong scientific basis for predicting earthquake damage.

Seismic Response of Concrete-Canvas Reinforced Slopes: Influence of Tilt Degrees for Reinforcement

2020 ◽  
Vol 14 (03) ◽  
pp. 2050011
Author(s):  
Lin Zhou ◽  
Guangya Ding ◽  
Jie Tan ◽  
Xiaoxia Zhao ◽  
Jun Wang
Keyword(s):  
Seismic Response ◽  
Threshold Level ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Slope Surface ◽  
Reinforcing Effect ◽  
Failure Patterns ◽  
Coral Sand ◽  
Before And After ◽  
Reinforced Slopes

A series of shaking table tests were conducted on reinforced slopes to study the slope dynamic characteristics. The influence of concrete-canvas tilt degrees on the seismic response was studied. By considering the effects of different concrete-canvas tilt degrees, the seismic responses of the reinforced slopes were analyzed, along with the accelerations, crest settlements, and horizontal displacements. The failure patterns of different model slopes were compared using white coral sand marks placed at designated elevations to monitor the internal slide of the reinforced slopes. Several round markers were placed on the slope surface to compare the deformation before and after shaking with different amplitudes. The results indicated that with the increase in concrete-canvas tilt degrees, a better reinforcing effect was obtained, and 30° reinforcement reached a threshold level, the slide-out point shifts from the crest of the slope to the middle of the reinforced model. The bottom 2/7th zone of the slope was relatively stable during the earthquake and the reinforcement was ineffective at the bottom of the slope. When both considered the influence of reinforcing effect and construction difficulty, 20° is the suitable tilt degree in concrete-canvas reinforced slopes. The characteristics of increasing strength of the concrete canvas make it suitable for the application in slope protection.

Seismic Response Estimation of Water Extinguishing Facilities using Shaking Table Tests

2012 ◽  
Vol 16 (4) ◽  
pp. 9-18 ◽  
Author(s):  
Min-Jun Nam ◽  
Seung-Hee Park ◽  
Dong-Joon Kim ◽  
Jun-Sung Choi
Keyword(s):  
Seismic Response ◽  
Shaking Table ◽  
Shaking Table Tests

Experimental Study on the Seismic Response of Subway Station in Soft Ground

2017 ◽  
Vol 11 (05) ◽  
pp. 1750020 ◽  
Author(s):  
Ma Xianfeng ◽  
Wang Guobo ◽  
Wu Jun ◽  
Ji Qianqian
Keyword(s):  
Seismic Response ◽  
Seismic Design ◽  
Shaking Table Test ◽  
Design Method ◽  
Underground Structure ◽  
Response Characteristic ◽  
Shaking Table ◽  
Subway Station ◽  
Soft Ground ◽  
Shaking Table Tests

Shaking table tests were conducted on typical models of subway structures subjected to several seismic shaking time histories to study seismic response of subway structures in soft ground as well as to provide data for validation of seismic design methods for underground structure. Three types of tests were presented herein, namely green field test, subway station test, and test for joint structure between subway station and tunnel. The similitude and modeling aspects of the 1g shaking table test are discussed. The seismic response of Shanghai clay in different depths was examined under different input waves to understand the acceleration amplification feature in both green field and in the presence of underground structure. Damage situation was checked on internal sections of both subway station and tunnels by halving the model structure. Structure deformation was investigated in terms of element strain under different earthquake loadings. The findings from this study provides useful pointers for future shaking table tests on underground structures/facilities, and the seismic response characteristic of underground structure derived from the shaking table test could be helpful for validating seismic design method for subway station.

scholarly journals Shaking Table Tests for Seismic Response of Orthogonal Overlapped Tunnel under Horizontal Seismic Loading

2021 ◽  
Vol 2021 ◽  
pp. 1-19
Author(s):  
Honggang Wu ◽  
Hao Lei ◽  
Tianwen Lai
Keyword(s):  
Dynamic Response ◽  
Seismic Response ◽  
Seismic Wave ◽  
Shaking Table Test ◽  
Shaking Table ◽  
Shaking Table Tests ◽  
Acceleration Response ◽  
Test Device ◽  
Deformation Stages ◽  
Superposition Effect

This paper presents the seismic dynamic response and spectrum characteristics of an orthogonal overlapped tunnel by shaking table tests. First, a prototype of the engineering and shaking table test device, which was used to design details of the experiment, was developed. Then, the sensors used in the test were selected, and the measurement points were arranged. Subsequently, the Wenchuan seismic wave with horizontal direction in different peak ground accelerations was inputted into the model, followed by a short analysis of the seismic response of the overlapped tunnel in the shaking table test as well as the distribution of the peak acceleration. Throughout the studies, the model exhibited obvious deformation stages during the seismic wave loading process, which can be divided into elastic, plastic, plastic enhancement, and failure stage. In particular, the time- and frequency-domain characteristics of the key parts of the tunnel were discussed in detail by using the continuous wavelet transform (CWT) based on the Morlet wavelet as the basis function. We found that the acceleration response was more intense within 25–60 s after the seismic wave was inputted. Furthermore, owing to “the superposition effect,” the seismic response at the crown of the under-crossing tunnel was stronger than that at the invert of the upper-span tunnel. The low and medium frequencies in the transformation of small scales (5–20) significantly affected the overlapped tunnel. These results elucidate the seismic dynamic response of the overlapped tunnel and provide guidance for the design of stabilizing structures for reinforcing tunnels against earthquakes.

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