Shaking Table Model Test Research Articles

Shaking Table Test and Numerical Modeling of Seismic Behavior of Rectangular Tunnel Structures Embedded in Soft Clay

In this paper, a series of 1-g shaking table model tests were carried out to investigate the seismic behavior of a relatively stiff rectangular tunnel structure installed in soft clay bed, accounting for different ground motions with varying peak accelerations. Using a validated numerical analysis procedure, a suite of three-dimensional (3D) finite element (FE) analyses was performed to systematically study the factors of tunnel burial depth, seismic intensity, flexural rigidity of the middle column and tunnel wall thickness on the seismic response of rectangular tunnel structures installed in clayey ground. It was found that, with the increasing burial depth, the seismic response of rectangular tunnel structure became more intense due to the increased inertial force arising from the overlying clay; in terms of improving the seismic performance of tunnel structure, increasing tunnel wall thickness seemed more effective than increasing flexural rigidity of the middle column. Furthermore, it was found that the existing simplified approaches generally tended to overestimate the earthquake-induced racking distortions of rectangular tunnels installed in clayey ground. A new semi-empirical relationship was derived for better correlating the racking ratio with flexibility ratio for rectangular tunnels embedded in soft clays, which could provide a useful reference for the seismic design and risk assessment of similar clay-tunnel systems.

Failure analysis and deformation characteristics of shield tunnel obliquely crossing ground fissure under earthquake

In order to study the deformation law and failure characteristics of shield tunnel obliquely crossing ground fissure under earthquake action, taking the shield tunnel of Xi ’an Metro Line 8 crossing f3 ground fissure as the engineering background, the 1: 20 shaking table model test method was used to analyze the strain of shield tunnel, the contact pressure with surrounding rock soil, the dislocation of segment and the axial force of bolt in detail, and the seismic damage mechanism and failure characteristics of shield tunnel obliquely crossing ground fissure were obtained. The test results show that under the action of earthquake, the shield tunnel has complex three-dimensional deformation characteristics, among which the vertical deformation is the most obvious. The deformation is mainly concentrated in the location of the ground fissure. The tensile strain and contact pressure of the hanging wall of the tunnel segment are greater than the strain value and contact pressure of the footwall. Because the vertical deformation of the tunnel is the largest, the bolts at the vault and the arch bottom are most obviously pulled. Excavation after the test, it can be seen that the tunnel appeared the phenomenon of ring joint opening, lining cracking and other damage. Under the action of the earthquake, the shield tunnel across the ground fissure is mainly subjected to tensile failure. The failure area is within 10 m from the ground fissure in the hanging wall and footwall, and the total length is 20 m. The closer to the ground fissure, the more serious the damage. The research results provide a scientific and reasonable reference for the subsequent construction and disaster prevention and mitigation design of Xi ’an Metro.

Full-scale experimental study on tribological performance of FPBs for highway bridges with various solid lubricants under fast loading

Friction pendulum bearings (FPBs) have proven to be effective for the seismic isolation of highway bridges. Previous studies often employed scaled model shaking table tests to investigate dynamic responses of the structures or quasi-static tests to assess the hysteretic performance of FPBs. However, it is noteworthy that the stress on the friction surface is reduced due to the size effect in scaled model in shaking table tests, while quasi-static tests of prototype bearings cannot simulate the sliding velocity experienced during seismic events, which is a sensitive parameter for the performance of FPBs with solid lubricant plates. Research on the performance of full-scale FPBs under fast frictional loading is very limited. This paper addresses this knowledge gap by studying the velocity demand for a highway bridge with FPBs and conducting fast sliding performance tests using full-scale FPBs. The results indicate that under a 0.2 g PGA earthquake, the velocity demand for FPBs can reach 0.5 m/s. Through testing full-scale FPBs at various loading speeds, it was found that solid lubricant plates by UHMWPE material exhibit poor thermal stability during wear tests, solid lubricant plates by PTFE material lack sufficient tangential tear strength under fast loading, and solid lubricant plates by PET material show good wear resistance but have a high breakaway force and levered maximum force during the running-in stage. Subsequently, this study developed ultra-high performance friction plate (UHPF) as the solid lubricant for FPBs, achieving ideal hysteretic performance under fast loading. The full-scale FPB specimens in this paper are the ones manufactured for the continuous beam bridges in the Shenzhen-Zhongshan Sea-crossing Link project in China. The dimensions of the bearing, axial load, and loading speed is much more stringent than those in previous FPB tests, providing results that are highly important for engineering applications.

Seismic response investigation of prestressed anchor cable supporting rock slope with weak interlayer in Qinghai-Tibet Plateau, China

Earthquake-induced rock landslides in the eastern mountains of the Tibetan Plateau, especially landslides with weak interlayers pose a significant threat to major construction projects. Prestressed anchor cable is one of the main reinforcement methods of rock slopes. This paper combines shaking table model tests and numerical simulation to study the reinforcement effect and dynamic response characteristics of prestressed anchor cables applied to rock slopes with weak interlayers under strong earthquakes. The research results show that prestressed anchor cables can effectively reinforce slopes with weak interlayers. A small cable inclination, a small spacing and a high prestress are recommended in the seismic reinforcement design of prestressed anchor cable. In addition, the characteristics of slope progressive damage and prestress loss under the earthquake are found by the shaking table test. The results have been applied in hazard prevention and control of rock slopes on the Chengdu-Lanzhou Railway at the eastern Qinghai-Tibet Plateau.

Vibration control and transmission mechanism of super high-rise building located on subway based on spring vibration isolation system

This study focuses on the vibration control effect of the spring vibration isolation system (SVIS) on a super high-rise building located on the subway (BLS) and the transmission mechanism of vibration in super high-rise BLS. Firstly, the 1:35 scale shaking table test model of super high-rise BLS is designed, the rationality of the shaking table test model is verified, and the shaking table test is implemented. Secondly, the finite element model (FEM) is established and verified based on the results of the shaking table test. Finally, based on verified FEM, the vibration control effect of SVIS on super high-rise BLS and the vibration transmission mechanism of super high-rise BLS is analyzed. The results show that the vibration response of the BLS show amplification trend along the height direction. The amplification of vibration response of BLS is effectively controlled by SVIS. The higher the floor, the greater the reduction coefficient, and the better the control effect. The reduction coefficient above 10F is mainly distributed above 0.80 due to the SVIS. The BLS equipped with the SVIS maintains the degree of Z-direction vibration and 1/3 octave vibration acceleration level that is within the limits stipulated by the specifications. The first-order vertical frequency of BLS equipped with the SVIS is adjusted from 65 Hz to 8 Hz, far from the favorable frequency range of the subway wave.

Shaking Table Model Tests and Stability Analysis of Slopes Reinforced with New Anti-Seismic Anchor Cables

Shaking Table Model Tests and Stability Analysis of Slopes Reinforced with New Anti-Seismic Anchor Cables

Seismically induced deformations of layered slopes with non-unique and non-planar slip surfaces

Earthquake-induced deformation is prevalently used to evaluate the seismic performance of slopes, often assumed to occur along a predefined single slip surface. This paper presents a new limit equilibrium method combining with Newmark sliding block analysis for calculating the seismic displacement of layered slopes with non-unique and non-planar slip surfaces. The determination of the most and subsequent critical slip surfaces during the earthquake shaking is discussed with an emphasis on the coupling effects between the shallow and deep failures. The approach is validated by the results from numerical simulation and the shaking table model test of layered slopes. Comparison analyses are also performed for the predictions of seismic displacement from the developed and previous sliding-block models. It is found that the seismic sliding deformation at the first slip surface significantly affects the evolution and sliding deformation of the subsequent slip surface. For the considered example of layered slope, a second slip surface at deeper location passing through the slope toe is identified, and a coupled variation is observed for the sliding displacement along the two slip surfaces. These features are not well predicted from the available sliding-block models. The developed model can capture the interaction between the non-unique slip surfaces and the geometry effect of the non-planar slip surfaces.

Analyses of Pile-Supported Structures with Base Isolation Systems by Shaking Table Tests

The dynamic behavior of a pile-supported structure with a base isolator was investigated by using 1 g shaking table model tests considering soil–structure interaction (SSI). The emphasis was placed on evaluating the effect of the with/without developed base isolator on the dynamic behavior of end-bearing piles and structures. The experiment was performed through sweep tests and sinusoidal wave tests. As a result of the tests, the developed base isolator was found to effectively reduce the structure’s resonant frequencies and damped the response acceleration under resonance frequencies. According to sweep tests, the base shear force of the pile-supported structure system tends to decrease as the relative density of the soil increases during resonance. It showed that the base isolator tends to reduce significantly the response acceleration of not only the rigid-based structure but also the pile-supported structure. It was shown that although the isolated superstructure recorded large horizontal displacements, piles experienced reduced horizontal displacement and bending moments, regardless of soil conditions.

Shaking table model test for seismic response of soft soil site

Soil sites play a crucial role during earthquakes and serve as conduits for the transmission of seismic effects from the bedrock to urban structures. Analyzing the dynamic response of soil sites to seismic waves is crucial as it presents deeper insights into earthquake damage mechanisms. In this study, we prepared a mixture of sawdust and medium sand with a 1:2.5 mass ratio to model soil samples from a soft soil site in Shanghai. The applicability of the scale-factor equation was verified using resonance column tests. A series of shaking table tests were conducted to simulate free-field site responses based on the dimensions, operating frequencies, and vibration modes of the shaking table at the State Key Laboratory of Disaster Reduction in Civil Engineering at Tongji University. Three different types of earthquake waves were selected as the input motions: TCU003 for far-field long-period seismic waves, TCU068 for near-field pulse-type seismic waves, and the El Centro earthquake wave. The Kramer frequency domain method was used to verify the transfer functions of the site seismic responses. Furthermore, discrepancies in the time–frequency distribution of the soft site responses influenced by various types of earthquake waves were assessed and analyzed. The seismic response characteristics of the soft soil sites under varying input intensities were also analyzed. The findings of this study present valuable reference data for the seismic zoning of soft-soil sites and facilitate the determination of seismic input parameters for engineering structures.

Seismic fragility analysis of slopes based on large-scale shaking table model tests

Seismic fragility analysis is one probabilistic method that represents the conditional probabilities of exceeding different predetermined damage states for various given earthquake hazard levels, which is the essential part of probabilistic seismic risk assessment. It has gained much popularity recently because much more comprehensive and richer results than traditional probabilistic methods can be provided. The classical seismic fragility analysis of slopes is always performed through analytical approaches. In the present study, a novel seismic fragility analysis framework combined with shaking table model test results is proposed for probabilistic seismic performance and risk assessment of slopes. The shaking table model tests of a rock slope reinforced by pile-anchor structures were firstly performed subjected to a suite of real earthquake records with different intensity levels. Subsequently, the seismic responses from shaking table model tests were then gathered for the optimal analysis to determine the optimal engineering demand parameter (EDP) and earthquake intensity measure (IM) for seismic fragility analysis of slopes. At last, the identified most appropriate IM and EDP were selected to construct the scalar-valued fragility curves, vector-valued fragility surfaces and fragility surfaces considering acceleration elevation amplification effect by the proposed framework. The results indicate that using single IM to construct scalar-valued fragility functions may result in different failure probabilities depending on the chosen earthquake IM. The vector-valued fragility surfaces provide more information than ordinary fragility curves, and lead to more proper and realistic evaluations of seismic hazard of slopes. The methods and results presented in this paper also provide the basis for the probabilistic seismic risk and loss assessment of earthquake-induced slope geological disaster.

Dynamic Failure Experimental Study of a Gravity Dam Model on a Shaking Table and Analysis of Its Structural Dynamic Characteristics.

Investigating the dynamic response patterns and failure modes of concrete gravity dams subjected to strong earthquakes is a pivotal area of research for addressing seismic safety concerns associated with gravity dam structures. Dynamic shaking table testing has proven to be a robust methodology for exploring the dynamic characteristics and failure modes of gravity dams. This paper details the dynamic test conducted on a gravity dam model on a shaking table. The emulation concrete material, featuring high density, low dynamic elastic modulus, and appropriate strength, was meticulously designed and fabricated. Integrating the shaking table conditions with the model material, a comprehensive gravity dam shaking table model test was devised to capture the dynamic response of the model under various dynamic loads. Multiple operational conditions were carefully selected for in-depth analysis. Leveraging the dynamic strain responses, the progression of damage in the gravity dam model under these diverse conditions was thoroughly examined. Subsequently, the recorded acceleration responses were utilized for identifying dynamic characteristic parameters, including the acceleration amplification factor in the time domain, acceleration response spectrum characteristics in the frequency domain, and modal parameters reflecting the inherent characteristics of the structure. To gain a comprehensive understanding, a comparative analysis was performed by aligning the observed damage development with the identified dynamic characteristic parameters, and the sensitivity of these identified parameters to different levels of damage was discussed. The findings of this study not only offer valuable insights for conducting and scrutinizing shaking table experiments on gravity dams but also serve as crucial supporting material for identifying structural dynamic characteristic parameters and validating damage diagnosis methods for gravity dam structures.

Predictions of seismic response for sheet-pile wall in liquefiable deposit within LEAP 2022 using the CycLiq constitutive model

The Liquefaction Experiments and Analysis Projects (LEAP) organized centrifuge tests and corresponding numerical predictions for the seismic response of sheet-pile wall in liquefiable deposits in 2022. Within LEAP 2022, two versions of the CycLiq constitutive model, i.e., the original (CycLiq) and modified (CycLiq-M) versions, were calibrated and used for numerical predictions. CycLiq-M was first calibrated using cyclic direct simple shear (CDSS) element tests on the test material, Ottawa F65 sand, and then used for Type-A predictions of another set of CDSS tests for which the results were priorly unknown, validating the model's performance at the element level. Type-B predictions of centrifuge shaking table model tests on sheet-pile wall in liquefiable deposit was then performed using both versions of the calibrated model, without prior knowledge of test results. The results show that the properly calibrated CycLiq model can make reasonable predictions for soil acceleration, excess pore pressure, settlement, and especially sheet-pile wall displacement. In particular, the CycLiq-M version with enhanced cyclic resistance simulation capability exhibits significant improvement in prediction accuracy. Using numerical simulation, the influence of soil-container friction in centrifuge model tests was assessed.

Analysis of Seismic Earth Pressure Acting on Basement Walls of Buildings Using 1g Shaking Table Model Test

Analysis of Seismic Earth Pressure Acting on Basement Walls of Buildings Using 1g Shaking Table Model Test

Physical modelling of the seismic response of well casings in liquefiable soil

ABSTRACT Liquefaction is a catastrophic phenomenon that poses a serious threat to lifelines during an earthquake. To assess the seismic behaviour of a well casing buried in saturated sand, a series of 1-g shaking table model tests were performed. The present study aims to investigate the impacts of the relative density and groundwater level on the base case as well. The responses of the models, including accelerations, pore water pressure changes, settlements, and strains induced along the well casing at various locations, were measured during the shaking. The outcomes illustrated that the groundwater level has a significant effect on the position of maximum strain. A rise in relative density leads to a 40.7% reduction in strains and moments caused along the well casing, while the rate of strain permanence in denser soils is considerable compared to looser soils. Moreover, experimental results indicated that the maximum shear force caused at the bottom of the well casing grows about 67% with increasing groundwater table.

Refined self-attention mechanism based real-time structural response prediction method under seismic action

Accurate prediction of structural response under earthquake is of great significance for structural damage and performance evaluation. In order to improve the efficiency of structure time history response prediction, this paper proposes a novel SeisFormer model based on the self-attention mechanism and deep learning technology. Through autoregressive prediction, the SeisFormer can achieve real-time prediction of the response time histories of a large number of nodes in the structure under seismic action and can effectively solve the problem of data scarcity. Four case studies are performed to verify the accuracy and efficiency of the proposed methodology, including validation on datasets obtained from elastoplastic seismic analysis of a single-story structure, a three-story structure, and an eleven-story structure, and measured data of a shaking table test model. In addition, this paper further studies the prediction accuracy of the SeisFormer through ablation experiments and comparative experiments. The experimental results show that the SeisFormer can accurately predict the acceleration, velocity, and displacement time histories of numerous nodes in the structure. The prediction accuracy outperforms the LSTM model, and the prediction speed is 193–109,824 times faster than finite element method. Furthermore, with data augmentation through autoregressive prediction, the SeisFormer model can achieve efficient and accurate predictions when training data is exceptionally scarce, enabling engineering applications.

Dynamic response characteristics of shaking table model tests on the gabion reinforced retaining wall slope under seismic action

In the present study, a series of shaking table model tests were performed on a slope with a gabion reinforced retaining wall. Transfer functions were employed to compute the inherent frequencies of the slope. Furthermore, the investigation examined various aspects of the slope, including the peak acceleration amplification factor, incremental dynamic stresses, displacements, and tensile forces. Additionally, the study employed the Hilbert Huang transform (HHT) to analyze the slope's time-frequency characteristics and energy distribution. The findings of the study revealed that there is an inverse relationship between the amplitude of the input seismic wave and the natural frequency of the top of the gabion reinforced retaining wall slope. As the amplitude of the seismic wave increases, the natural frequency of the slope decreases. The amplification factors for peak acceleration were all found to be less than 1.9, suggesting a notable dissipation of seismic energy in comparison to typical slopes. The response of incremental dynamic stress was most pronounced in the middle section of the slope, followed by the top of the slope. The magnitude of the incremental displacement was found to be highest at layer 4, whereas the incremental tensile force exhibited its maximum value at layer 5. The dynamic response exhibited the least pronounced characteristics at the lower portion of the slope, demonstrating the most stable behavior. The peak frequencies observed in the Hilbert marginal spectrum displayed comparable characteristics to the natural frequencies.

Dynamic damage evolution of bank slopes with serrated structural planes considering the deteriorated rock mass and frequent reservoir-induced earthquakes

To investigate the dynamic damage evolution characteristics of bank slopes with serrated structural planes, the shaking table model test and the numerical simulation were utilized. The main findings indicate that under continuous seismic loads, the deformation of the bank slope increased, particularly around the hydro-fluctuation belt, accompanying by the pore water pressure rising. The soil pressure increased and then decreased showed dynamic variation characteristics. As the undulation angle of the serrated structural planes increased (30°, 45°, and 60°), the failure modes were climbing, climbing-gnawing, and gnawing respectively. The first-order natural frequency was used to calculate the damage degree (Dd) of the bank slope. During microseisms and small earthquakes, it was discovered that the evolution of Dd followed the “S” shape, which was fitted by a logic function. Additionally, the quadratic function was used to fit the Dd during moderately strong earthquakes. Through the numerical simulation, the variation characteristics of safety factors (Sf) for slopes with serrated structural planes and slopes with straight structural planes were compared. Under continuous seismic loads, the Sf of slopes with straight structural planes reduce stalely, whereas the Sf for slopes with serrated structural planes was greater than the former and the reduction rate was increasing.

Dynamic response and progressive damage modes of fault-crossing tunnels simulated using similar materials

Tunnels are widely constructed because they can effectively withstand seismic loads and avoid tunnel collapse in high-intensity seismic zones. However, in the case of fault-crossing tunnel, the fault crossing tunnel will be seriously damaged in seismic activities because the tunnel lining follows the deformation of surrounding rock. Therefore, the researches of the dynamic response and failure modes of fault-crossing tunnel are highly significant. In this study, quartz sand, cement and detergent were used to simulate similar materials of surrounding rock. A gypsum-based materials have been selected as similar materials for tunnels. The shaking table model tests were conducted on fault-crossing tunnel and conventional tunnel based on the Xianglushan Tunnel. The dynamic response characteristics of the fault-crossing tunnel were analyzed, and draw the conclusions: The acceleration amplification coefficients of the two sets of tests exceeded 1. The acceleration dynamic response of the fault-crossing tunnel was greater than the conventional tunnel, and the acceleration dynamic response at the fault was greater than the monitoring surface on both sides, rendering the acceleration dynamic response at the fault abrupt. Compared to other cross sections, tunnel lining structures at faults had the strongest dynamic response. The maximum peak strain value of the fault-crossing tunnel was magnified 4.4 times, and the bending moment value was magnified 2.3 times, relative to those of the conventional tunnel. The fault markedly increased the strain peak and bending moment values, causing cracks and damage even at a small peak acceleration value, weakening the seismic capacity of the tunnel. The lining at the fault was dominated by longitudinal cracks, and dislocation occurred. The degree of destruction and development of tunnel at faults was greater than that of other cross sections. The research results and conclusions could provide a reference to prevent the destruction of fault-crossing tunnel in an earthquake.

Novel Methodology for Scaling and Simulating Structural Behaviour for Soil–Structure Systems Subjected to Extreme Loading Conditions

This paper is concerned with the calibration and validation of a numerical procedure for the analysis of pile performance in soft clays during seismic soil–pile–superstructure interaction (SSPSI) scenarios. Currently, there are no widely accepted methods or guidelines. Centrifuge and shaking table model tests are often used to supplement the available field case histories with the data obtained under controlled conditions. This paper presents a new calibration method for establishing a reliable and accurate relationship between full-scale numerical analysis and scaled laboratory tests in a 1g environment. A sophisticated approach to scaling and validating full-scale seismic soil–structure interaction problems is proposed that considers the scaling concept of implied prototypes as well as “modelling of models” techniques that can ensure an excellent level of accuracy. In this study, a new methodology was developed that can provide an accurate, practical, and scientific calibration for the relationship between full-scale numerical analysis and scaled laboratory tests in the 1g environment. The framework can be followed by researchers who intend to validate their seismic soil–structure interaction findings.

Dynamic Response of the Cross Tunnel with Ultra-Small Spacing Under Various Seismic Motions Using a Shaking Table Model Test

ABSTRACT Different from a single tunnel, the cross tunnel with ultra-small spacing is characterized by high crossing risk, significant coupling of multiple effects, and difficulty in controlling stability. A shaking table model test was carried out to study the failure process and dynamic response of the cross tunnel with ultra-small spacing under seismic motions with various types and peak accelerations. The results show that the seismic damage of the cross tunnel model has significant failure stages. The deformation of the upper-span tunnel lining is cumulative progressive damage from the left wall to the invert, while the under-crossing tunnel lining is cumulative progressive damage from the left wall to the crown. The acceleration response of the model when inputting Wenchuan seismic motions is greater than that of El-Centro seismic motions, and the Wenchuan seismic motions may cause a peak lag in the acceleration response of the model. Compared with inputting El-Centro seismic motions, the 1st predominant frequency of the model increases while the 2nd predominant frequency decreases when inputting Wenchuan seismic motions. Additionally, the 2nd predominant frequency components are significantly amplified in the propagation of seismic motions from bottom to top through the lining structure. Although the energy ratio of the wavelet packet frequency components gradually tends from low-frequency bands to relatively high-frequency bands, the low-frequency bands still play a dominant role in the failure of the model.