Pier Settlement Research Articles

Riding safety prediction of a high-speed train running on transition zone under foundation settlement

The settlement of piers and subgrade bending deformation are widely recognized as common issues in the transition zones of high-speed railway bridges. This study aims to investigate the settlement behavior within these transition zones and its impact on the dynamic interaction between trains and the track. To achieve this, a vehicle-track-transition zone mapping relationship model is developed to analyze both the settlement behavior and the resulting dynamic response characteristics. The study employs the finite element method and multi-body dynamics to construct the simulation model. Settlement effects are simulated using the Newton-Raphson iterative method, with the additional rail deformation caused by foundation settlement serving as the excitation for the vehicle-track-transition zone dynamic interaction system. In the numerical analysis, the dynamic effects of three key factors—train speed, transition zone length, and the amplitude of foundation settlement—are examined based on the performance of the vehicle-track-transition zone interaction. The time-frequency technique is utilized to comprehensively reveal and clarify the spatial-frequency characteristics of system responses influenced by settlement excitation. Moreover, the relationship between the safety-based settlement threshold and these three factors is calibrated.

Dynamic “Disengagement-Closure” Contact Characteristics of Track–Bridge Interface Caused by High-Speed Train Under Side Pier Settlement

A nonlinear dynamic model of a train–bridge-longitudinal track coupling system considering the dynamic contact of the bridge–track interface (BTI) is established. Based on the previously established BTI contact characterization model and train–bridge coupling joint simulation model, the proposed model is verified from both static and dynamic perspectives. Accordingly, the dynamic displacement variation law of the bridge–track structure before, during and after the train passing through the side pier settlement area, the additional stress dynamic variation law and the interlayer connection dynamic variation law are analyzed. Moreover, the amplification effect of the wheel repeated “beating effect” on the dynamic contact force of “disengagement-closure-redisengagement” of the BTI void area is also analyzed. The results show that the accuracy of the proposed model can be verified from both static and dynamic perspectives. During the train passes through the settlement area, the dynamic deformation of track is the largest. Before and after the train passes through the settlement area, the dynamic deformation of track is basically the same. During the train passes through the settlement area, the BTI completes a dynamic contact process of “disengagement-closure-redisengagement”. The static effect of the side pier settlement on the dynamic bonding force of sliding layer is much larger than the dynamic effect of the train load. The dynamic effect of the train load is much larger than the static effect of the side pier settlement on the dynamic bonding force of the CA mortar and fasteners. The side pier settlement has a dynamic amplification effect on the train wheelset. Along the mileage direction, there are interface voids and contact areas in the dynamic bonding force of sliding layer and CA mortar, while there are no voids and contact areas in the dynamic bonding force of fasteners.

Computer Vision-Based Pier Settlement Displacement Measurement of a Multispan Continuous Concrete Highway Bridge under Complex Construction Environments

Various concrete bridges have been built across oceans, valleys, and mountains; however, the settlement displacement of bridge piers caused by environmental changes or self-weight during construction phases often leads to uneven stresses, cracking, and eventual collapse. To address the labor-intensive and high-cost issues of pier displacement monitoring using contact-type sensors, this paper proposes an automatic vision-based method for measuring pier settlement displacement under complex construction environments, such as complex image backgrounds, varying ambient light, and camera movement. In the proposed method, a deep learning network was first employed to eliminate the adverse effect of complex image backgrounds and varying ambient light on the accuracy of target detection; then, an adaptive displacement extraction algorithm without a human-computer interaction process was developed to automatically extract the center coordinates of targets attaching to the bridge piers and reference platform; finally, the pier settlement displacement was calculated by using the relative displacements obtained by a dual camera system to eliminate the measurement error caused by camera translation and rotation movements. Laboratory tests of a cantilever beam and field tests of a continuous multispan concrete girder highway bridge under construction have successfully validated the effectiveness and robustness of the developed methodology. The results obtained in this paper can provide some insights for engineers in applying computer vision technology for the real-time monitoring of bridge displacements.

Structural Health Monitoring Design and Performance Evaluation of a Middle-Span Bridge

Structural health monitoring (SHM) has attracted significant attention over the past two decades due to its ability to provide real-time insight into the condition of structures. Despite the development of several SHM systems for long-span bridges, which play a crucial role in the assessment of these structures, studies focusing on short- or middle-span bridges remain scarce. This research paper presents an efficient and practical bridge monitoring and warning system established on a middle-span bridge, a key crossroad bridge located in Shenzhen. The monitoring system consists of sensors and measuring points that collect a substantial amount of data, enabling the close monitoring of various operational indicators to facilitate the early detection of threshold exceedances. Based on this system, the subtle condition of the bridge can be evaluated, and the operational condition of the bridge can be studied through the comparative analysis of the collected data. Over four months of monitoring, data including the strain and creep of the main beam, the strain and settlement of piers and the crack width of the bridge body are observed. Furthermore, the real-time operational status of the bridge is analyzed and evaluated through the combination of the collected data and the structural finite element model.

Reliability of super-slope rack railway under bridge pier settlement

Bridge pier settlement always occurs on the super-slope rack railway, which has serious impact on reliability and stability of rack-bridge system. Aiming at this issue, a coupled dynamic model of the super-slope vehicle-rack(track)-bridge system under pier settlement is established considering gear-rack nonlinear meshing behavior, wheel-rail nonlinear contact behavior and pier settlement. On this basis, the mechanical characteristics of gear-rack system induced by pier settlement are studied. Then, the dynamic influences of two common gear-rack connections (rigid connection and elastic connection) on the adaptability and safety of this system are discussed. Finally, the safety control value of pier settlement of the large-slope railway in mountainous areas is proposed. Results show that pier settlement potentially leads to fracture of gear-rack fasteners under multi-loads such as gear-rack meshing and wheel-rail contact. When the rack and the sleeper are rigidly connected, the maximum shear stress of the fastener is 346.43 MPa when the settlement is 10 mm, which seriously exceeds the standard limit (235 MPa). When they are elastic connected, the maximum shear stress of the fastener is 262.80 MPa, slightly exceeding the limit value. The structural stress of rack is far less than the tensile strength of rack. Under the two connection modes, the maximum deformation of the rack is 14.02 mm and 11.08 mm respectively, which is about 140% and 125% of the pier settlement. The main frequencies of the vibration of the rack are located at 70 ∼ 80 Hz and 65 ∼ 70 Hz respectively. Pier settlement has a significant effect on the stress of the fastener and the deformation of the rack, but has little effect on the vibration and stress of the rack railway.

Long-term settlement of metro viaduct piers: A case study in Shanghai soft soil

This study aims to investigate the long-term settlement behavior of metro viaduct piers in soft soil in Shanghai. Field monitoring was conducted for eight years, from the official opening until 2021. The results indicate that the settlement rate of the majority of piers was higher in the initial years and gradually reduced since 2017. Up to 2021, the maximum cumulative settlement St was 15.9 mm, which accounted for 0.8 times the limit of St (Ut). Seven settlement troughs were observed during the monitoring period. Muddy soil and nearby rivers significantly influenced the long-term pier settlements. St decreased proportionally with the thickness of the muddy soil. Piers located near the river experienced higher settlements than those located farther away, with a maximum settlement difference of 0.28–0.42 Ut. The influence of the river on St extended up to a range of 3–4 times the width of the river (Wr). Additionally, there were noticeable differences in settlement between piers constructed with tubular piles and those constructed with bored piles, particularly during the first two years after completion. Under similar conditions, the St of piers with tubular piles were 0.28 Ut (5.5 mm) larger than those of piers with bored piles on average. In addition, the slope k between the excavation-induced pier settlement and the ratio of the excavation depth to the distance was closely related to the type of retaining structure. The ratio of k values for the pit wall soil reinforcement, row piles and diaphragm wall was approximately 4:2:1. To prevent excessive pier settlement under similar geological conditions, it is recommended to employ a more rigid retaining structure and avoid using a soil-reinforced enclosure for pit walls.

Deformation mapping between pier settlement and maglev track for high-speed multi-span simply supported maglev bridge

When a bridge pier settles, deformation of the complex coupling between a maglev track and girders may occur because of the disparity between the continuity of the maglev track and discontinuity of the simply supported girder bridge. This introduces additional irregularity to the track, resulting in the combined vibration of the maglev train–bridge system. In this study, a high-speed maglev track–simply supported bridge is considered as the research object. The deformation characteristics of the maglev track caused by the pier settlement are analysed. First, the mapping relationship between the settlement of a single pier and the deformation of the maglev track is theoretically deduced. Then, an analytical model for the deformation of the maglev track is developed. The model is compared with a finite element model and found to have sufficient accuracy. The additional irregularity of the maglev track includes the rigid displacement caused by pier settlement and the elastic displacement influenced by the track and girder. The elastic deformation of the longitudinal beam of the maglev track is the main component of the deformation in the vertical displacement of the maglev track. Based on the established analytical model, the elastic deformation of the longitudinal beam of the maglev track and its main influencing factors are further examined.

Combined Prediction Model for High-Speed Railway Bridge Pier Settlement Based on Robust Weighted Total Least-Squares Autoregression and Adaptive Dynamic Cubic Exponential Smoothing

Combined Prediction Model for High-Speed Railway Bridge Pier Settlement Based on Robust Weighted Total Least-Squares Autoregression and Adaptive Dynamic Cubic Exponential Smoothing

Assessment of railway bridge pier settlement based on train acceleration response using machine learning algorithms

To meet up with the safety and design requirements of High-Speed Railways, bridge structure has become an essential part of the lines occupying up to 90% of the mileage. Bridge pier settlement has proven to be an inevitable phenomenon, despite its critical effect on the train-track-bridge system, affecting passengers’ comfort and endangering operation safety. For this reason, different theories and techniques have been employed to assess bridge pier settlement. However, few attempts have been made to utilise train vertical acceleration, the most sensitive index, to estimate pier settlement, which has the potential to save time and overcome all the other methods' geographical and economic challenges. In this study, a CRH380A high-speed train acceleration response dataset is obtained using train-track-bridge interaction simulation in Simpack. The dataset is used to train three machine learning models selected based on PyCaret. The model test results proved that pier settlement can be accurately predicted using train vertical acceleration response. Gradient boost regressor outperformed the other models on the test result with an R-squared of 99%, a mean absolute error of 0.39, and a mean squared error of 0.24. Extra tree regressor is the second-best model on the test result, with an R-squared of 98%, a mean absolute error of 0.56, and a mean squared error of 0.47. The random forest regressor test result has an R-squared of 97%, a mean absolute error of 0.73, and a mean squared error of 0.75. Additionally, over 70% of the gradient boost test prediction error is below 0.5 mm, and the maximum error is 1.5 mm, demonstrating the accuracy of the machine technique to predict pier settlement using the vertical acceleration response of the train.

Preliminary results of parametric study of structural behaviour of Persian brick masonry groined multipartite (Tarkin) vaults

In this paper, the structural behaviour of Persian brick masonry groined quadripartite, sexpartite and octopartite vaults is studied. Three different spans, three different pier heights and three different pier widths adopted from real structures are considered. Seven different cross-sectional shapes are selected for the vaults and the supporting arches. Vaults are subjected to four cases of pier settlement and seven cases of pier rotation. Three-dimensional non-linear finite element has been used for analysis. Results show that the load bearing capacity is sensitive to the type of the vault and the shape of the arches, to the type of pier settlement and pier rotation. Ranges for the pier height to the pier width ratio for the highest resistance of the vaults are proposed for pier settlement and rotation.

The Network of Railway Settlements of the Tobolsk Province in the Late XIX - Early XX Century

Based on the analysis of mass sources – archival documents of the First General Population Census of the Russian Empire in 1897 and information published by the Tobolsk Provincial Statistical Committee for 1903 and 1909, the number, typical diversity, and population of settlements formed in the exclusion zone of the Perm-Tyumen and West Siberian railways on the territory of the Tobolsk province is determined. A set of statistical methods was used to analyze the sources. A comprehensive interdisciplinary approach allows not only to identify the historical and genetic features of individual documents, but also to give a certain assessment of their representativeness and information potential for specific historical research. Intensive construction of railways has led to the emergence of new types of settlements: stations, independent settlements at stations and on the railway line, barracks and semi-barracks, booths, barracks, guard houses, etc. In 1897, at least 128 railway settlements were functioning on the territory of the province, which was about 2.5% of the total number of all settlements in the studied region. More than two thousand people lived in them permanently and temporarily; on average, there were 18 people per settlement. The major settlements were the Tyumen and Kurgan stations. It is concluded that the primary materials of the 1897 census have the most complete information. In connection with the further construction of the Trans-Siberian railway at the beginning of the XX century, there is an increase in the population of stations and pier settlements, their merger, the emergence of new types of railway settlements.

Failure mode of interlayer connection of longitudinally-connected ballastless track-bridge system under uneven pier settlement

• Proposing the characterization model of uneven pier settlement and interlayer connection failure in LBTBS. • Analysing the generation mechanism and development law of interlayer connection failure caused by uneven pier settlement. • Describing the evolution law of interlayer contact behavior of each layer of track caused by uneven pier settlement considering the existing interlayer connection failure. The generation and mechanical balance mechanisms and the deformation compatibility relationship of interlayer connection failure (ICF) of a longitudinally-connected ballastless track-bridge system (LBTBS) caused by uneven pier settlement is analyzed in this paper. The characterization model of the uneven pier settlement and the ICF of the LBTBS was derived based on Castigliano's Second Theorem, Linear Superposition principle, Heaviside function, and Tension-free Winkler beam. The characterization model was further verified by the field measured data and finite element model results. Finally, the development law of the ICF of the LBTBS caused by uneven pier settlement based on the characterization model was analyzed. The results show that the calculated results of the characterization model agree well with the field measured data and finite element model results, which verifies the correctness of the characterization model. Under uneven pier settlement, a void beneath the slab first appeared between the base slab and bridge, and then mortar debonding occurred between the CA mortar and track/base slab when settlement value is 193.48 mm. The maximum height of void beneath the slab developed away from the beam gap, and when the settlement value was less than 8.434 mm, the void beneath the slab length in the left area of the settlement pier was greater than that of the adjacent pier. With the increase in mileage, the height of the void beneath the slab and mortar debonding increased first and then decreased. In practical engineering, mortar debonding is not easy to notice, and the void beneath the slab between the base slab and the bridge should be inspected regularly. The existing fastener failure had little influence on developing a void beneath the slab caused by the uneven pier settlement. The existing mortar void aggravated the occurrence of mortar debonding. When the existing mortar void length exceeded 5 m, the mortar debonding length at both ends of the adjacent pier was about 1/2 of the existing mortar void length. When the length of the existing mortar void was less than 1 m, there was little effect on the length of the void beneath the slab.

An Analytical Solution for the Geometry of High-Speed Railway CRTS Ⅲ Slab Ballastless Track

To study the mapping relationship between girder deformation and rail deformation for the CRTS Ⅲ slab ballastless track (SBT) multi-span simply supported bridge, this study derived a simplified analytical solution, and the corresponding ANSYS finite element model (AFEM) was established. Compared with the fine analytical model (FAM) and the AFEM, the calculation results of the three models under the conditions of pier settlement and girder vertical fault were compared, which verified the universal properties of the simplified analytical model (SAM). Based on the verified SAM, the influence of pier settlement, fastener stiffness, girder span, and girder vertical fault on rail deformation was studied. The results show that the rail deformation is approximately proportional to pier settlement and girder vertical fault. With the increase in fastener stiffness, the fastener internal force increases, the rail mapping deformation increases, and the length of the rail mapping deformation area decreases. With the increase in girder span, the rail deformation curve becomes smooth, the length of the rail mapping deformation area becomes longer, and the fastener internal force is significantly reduced.

Observed performance of a deep excavation of Qingdao Metro Line 4 in China

The L-shaped excavation of Anshan Road Station, with the maximum excavation depth of about 40 m, is one of the deepest excavations of Qingdao Metro Lines in Qingdao, Shandong Province, China. The deep excavation was constructed mainly in coarse-grained granite of different weathering degrees. A comprehensive field monitoring scheme was carried out to study excavation-induced ground movement and the response of nearby structures. Characteristics of ground surface settlement and pier settlement of Hang’an Expressway Viaduct adjacent to sub-zone D of the L-shaped excavation was studied based on the long-term monitoring data. A high-risk zone of rock failure at sub-zone D was successfully identified based on abnormal variations in the horizontal displacement of pile head and axial force of cable, concentration of microseismic events, and development of a 44-m-long longitudinal crack adjacent to the excavation boundary. A temporary bracing system, consists of two layers of steel struts and built-up steel columns, was designed and conducted to maintain the stability of the high-risk zone of rock failure at sub-zone D. Furthermore, effectiveness of the temporary bracing system in controlling rock failure of the L-shaped excavation was validated by analyzing the evolution of the axial force of steel struts, horizontal displacement of pile head and axial force of cable. This study may be valuable for monitoring, warning and controlling rock failure of deep excavations in hard rocks in dense and busy urban areas.

Data driven structural damage assessment using phase space embedding and Koopman operator under stochastic excitations

To address the issue faced by phase space trajectory (PST) based methods for identifying structural damage using high dimensional dynamic responses of structures under stochastic excitations, a novel data driven approach for structural damage assessment based on phase space embedding in conjunction with stochastic Koopman operator, is proposed in this study. Vibration acceleration responses are used to reconstruct the phase space representation of system dynamic attractor using embedding strategy, followed by subspace dynamic mode decomposition (subspace DMD) to estimate the unbiased eigenvalues of the corresponding stochastic Koopman operator. Under the hypothesis that the Koopman operator eigenpairs will vary with structural condition change, the Mahalanobis distance of Koopman operator eigenvalues approximated from heathy state and current testing state is introduced as a damage sensitive feature (DSF) to detect structural damage. A planar truss model is adopted in numerical studies to demonstrate the feasibility and applicability of the proposed approach. The robustness of the proposed approach under operational and environmental variations is tested by considering 10% white noise in vibration measurement and six different ambient loading scenarios. Numerical results show that the proposed approach is sensitive to the occurrence and severity of structural damage, and is insensitive to the measurement noise and the variation of stochastic excitation amplitudes. Furthermore, the proposed method is applied to identify damage introduced as the artificially applied settlements of pier in the Z24 benchmark bridge. Results demonstrate that the bridge condition under the reference state and the damage scenarios with different levels of pier settlement are well identified by using the proposed approach with in-field measurement data including different test environment. The defined DSF value can be used to reflect the damage severity in these damage scenarios.

Moving Safety Evaluation of High-speed Train on Post-earthquake Bridge Utilizing Real-time Hybrid Simulation

ABSTRACT This study aimed to provide an experimental evaluation method for train’s moving safety on a post-earthquake bridge. First, an improved real-time hybrid simulation (RTHS) framework was constructed, based on utilizing the moving load superposition algorithm to solve the train-track-bridge interaction (TTBI) problem. An RTHS test was then conducted for the TTBI problem. The train model was tested using a shake table and was dynamically linked to the numerical substructure. A post-earthquake seven-span high-speed railway simply supported bridge was studied, in which earthquake-induced damage, such as stiffness reductions, residual displacements of piers, girder gap expansions, and pier settlements were all tested.

A High-Precision Distributed Microdisplacement Monitoring System: System Design and Data Processing Algorithms

For large-scale constructions, micro-displacement may accumulate over time and it is possible that the large-scale constructions have disastrous consequences such as deformation, cracking, or collapse, resulting in irreparable losses. In order to avoid the occurrence of tragedy, it is crucial to monitor the micro-displacement of constructions timely and accurately, apart from the operation and maintenance of large-scale structures. There are several challenges to fully automatic monitoring of micro-displacements of large-scale structures, including the lack of reference points due to structural complexity, various environmental disturbances, and the trade-off between low cost and high precision. In this paper, a measurement device with low cost, high accuracy, and wide applicability is designed to provide real-time monitoring of the micro-displacement of large-scale structures. A comprehensive system is designed and a data processing algorithm based on data reconciliation is proposed to effectively alleviate the influence of measurement errors. This system is successfully applied to pier settlement detection for high-speed railways, which achieves the desired accuracy. The system we developed can be directly applied to many situations of micro-displacement monitoring of large buildings, with high accuracy and low cost.

Uneven settlement threshold of continuous beam pier based on analytic mapping relationship

Currently, there is no regulation on the settlement threshold of continuous beam bridge pier of high-speed railway (HSR), a method is proposed in the present study to calculate the settlement threshold of continuous beam pier based on the analytic mapping relationship. First, the dynamic model of the train-track-continuous beam bridge was established. Then, the mapping rail irregularities caused by pier settlement obtained from the analytic mapping relationship superimposed with the initial rail irregularities converted from the Chinese track irregularities spectrum by using the trigonometric series method. Furthermore, the proposed method was verified by comparative analysis with the measured data and the existing results. Finally, the types and thresholds of uneven settlement of continuous beam bridge pier were revealed based on the parameter discussion method. It was found that the influence of pier settlement on the train dynamic performance index had a strong correlation with the train running direction. The settlement threshold of long-span continuous beam pier was looser than that of simply supported beams with a 32 m span. The settlement threshold of continuous beam piers can be appropriately relaxed in design.

Vibration-based multiclass damage detection and localization using long short-term memory networks

This paper proposes a novel damage detection and localization method of civil structures using a windowed Long Short-Term Memory (LSTM) network. A sequence of windowed samples are extracted from acceleration responses in a novel data pre-processing pipeline, and an LSTM network is developed to classify the signals into multiple classes. Predicted classification of a signal by the LSTM network into one of the damage levels indicates the presence of damage. Furthermore, multiple structural responses obtained from the vibration sensors placed on a structure are provided as input to the LSTM model, and the resulting predicted class probabilities are used to identify the locations with a high probability of damage. The proposed method is validated on the experimental benchmark data of the Qatar University Grandstand Simulator (QUGS) for binary classification, as well as the Z24 bridge benchmark data for multiclass damage classification associated with different levels of pier settlement and the numbers of ruptured tendons. The results show that the proposed LSTM-based method performs on par with the one dimensional convolutional neural network (1D CNN) on the QUGS dataset and outperforms 1D CNN on the Z24 bridge dataset. The novelty of this paper lies in the use of recurrent neural network-based windowed LSTM for multiclass damage identification and localization using vibration response of the structure.

Cooperative Work of CRTS II Slab Ballastless Track-32m Simply Supported Girder under Pier Settlement

Compared with the previous model, a simplified mapping model of CRTS II slab ballastless track between pier settlement and the vertical deformation of rail was proposed based on Timoshenko's beam theory. A cooperative finite element analysis model was established for verification purpose and the analysis of interlaminar stress. The results showed that the emergence of pier settlement causes the appearance of the void of the sliding layer between the base plate and the box girder above the piers, and the shear cogging reduces the void length to a certain extent. It was also observed that the rail is deformed cambered at the side pier (the pier with no settlement on both sides of the middle pier) and downwards at the middle pier (the pier with settlement). Moreover, the comparison between the theoretical value of the rail deformation and the finite element result demonstrated that the proposed mapping model can precisely characterize the relevant relationship. A conclusion also can be drawn that the pier settlement is attributed to the additional stress on the interface between the track slab and cement and asphalt mortar (CA mortar), and the interfacial stress is increased due to the effect of shear cogging.