Unknown Foundations Research Articles

Efficient Bayesian model updating for settlement prediction of the immersed tunnel of HZMB

To predict the settlement of the Hong Kong-Zhuhai-Macau Bridge (HZMB) tunnel, a physics-informed machine learning (PIML) algorithm was proposed. This method is effective in predicting total settlement with limited training data. However, its performance is poor when applied to the prediction of joint differential settlement, indicating that the commonly used physical model in the algorithm needs further updating. To ensure the efficiency of model updating, a synthetic case study is employed to demonstrate that prediction performance is inconsequential to the simplification of joint shear stiffness but rather to the insufficient number of foundation moduli in the physical model. Subsequently, five criteria are proposed to guide the model design process and guarantee the efficiency of model class selection. The PIML algorithm and the Bayesian probabilistic approach are then employed to select the most suitable model for predicting settlement. The results of model class selection indicate that the criterion related to tube differential settlement is the optimal choice for the HZMB tunnel, with an optimal number of 57 unknown foundation moduli in the updated model. The analysis with field data proves that the updated model class effectively improves predictions for both total settlement and joint differential settlement.

Pile length estimation based on guided wave theory and dispersion analysis for reuse of foundations

The construction of new structures on existing pile foundations can significantly reduce the overall project costs. The reuse of foundations requires information on the embedded depth of existing piles, which is not always known. In this paper, a novel technique based on the periodic analysis of the phase difference and the 3-dimensional guided wave theory was developed to effectively estimate the embedded depth of unknown foundations. In this method, the guided wave model of a cylindrical pile is built by the spectral element method to determine the dispersion relation. A modified Ridders’ algorithm is proposed for root-searching. According to the phase difference of the responses collected by at least two sensors located on top or the lateral side of the pile, and the dispersion relation obtained by the spectral element method, the dispersion analysis diagram can be obtained to show the relationship between the phase difference and the wavenumber. Through the periodic properties of the dispersion analysis diagram, the pile length can be estimated. Furthermore, the periodic analysis of the phase difference for the signals collected on top of the pile is conducted in this paper using the 3-dimensional guided wave model-based dispersion relation. By comparing with synthetic and experimental data, it was shown that the proposed method can achieve an accuracy of greater than 95% in estimating the pile length of unknown foundations.

A single-sensor system for length estimation of unknown piles using guided waves

The practice of reusing unknown foundations in construction projects involves using existing foundations, even though there may be limited knowledge about their geometric and physical characteristics, conditions, and stability of the soil layer and the buried structure. Accurately estimating the pile length is a critical aspect of this practice. In this study, we introduce a new pile length estimation method based on guided wave theory and utilizing only one sensor for data collection. The objective is to enhance operational flexibility in the characterization of unknown piles, in terms of data acquisition, sensor placement, and accuracy in pile length estimation. The sensor can be positioned either on the lateral side of the pile or on its top surface. The recorded responses in the frequency domain are analyzed, and their normalized magnitude is calculated. Using the dispersion relation determined by the guided wave model, we obtain the dispersion analysis diagram of the wavenumber as a function of the normalized magnitude of the recorded response. By performing periodic analysis of the dispersion analysis diagram, the pile length can be estimated. Our proposed method has been verified using both synthetic and experimental data. The results demonstrate the efficacy and accuracy of the proposed method.

Guided wave and genetic algorithm-based inversion for characterization of pile foundations

The characterization of geometric and mechanical properties is of great importance for the reuse of unknown foundations. In this paper, we propose a pile characterization method to non-invasively estimate the length and mechanical properties of a pile simultaneously and automatically. The forward model is established based on the guided wave theory for a cylindrical pile and a genetic algorithm-based method is proposed for the inversion process. The guided wave model is built using the spectral element method, which can generate the dispersion relation for the given physical properties. The resonance data (including the resonance frequency and the resonance number) and pile length can be related to the phase velocity, which can be derived by assuming either the displacement control or stress control boundary conditions. The loss function in the inversion method is defined by linking the dispersion relation of the forward model and the resonance analysis for those two boundary conditions. The proposed method is validated against the experimental data. By using the proposed method, pile characterization can be achieved automatically. The average accuracy of the proposed method for characterizing the pile properties (such as pile length, shear wave velocity, and longitudinal wave velocity) and the pile length is within 5% error for each variable.

A machine learning framework for in situ sensing of pile length from seismic cone penetrometer data

Several hundred high mast light towers (HMLTs) throughout the state of Minnesota have foundation systems, typically concrete-filed steel pipe piles or steel H-piles, with no construction documentation, e.g., pile lengths. Reviews of designs within current standards suggest that some of these foundations may have insufficient uplift capacity in the event of peak wind loads. Without knowledge of the in situ pile length, an expensive retrofit or replacement program would need to be conducted. Thus, developing a screening tool to determine in situ pile length – as compared to a bulk retrofit of all towers with unknown foundations – would provide significant cost savings. The goal of the project is to establish a non-destructive evaluation (NDE) technique, including the testing setup and data analysis algorithms, for determining in situ pile lengths by way of seismic waves. This work specifically focuses on (i) the use of ground vibration waveforms captured by a seismic cone penetrometer; (ii) three-dimensional visco-elastodynamic finite element method (FEM) used as a tool to relate the sensory data to in situ pile length; and (iii) the use of machine learning (ML) algorithms, trained with the outputs of FEM simulations, to solve the germane inverse problem. In principle, the scarcity of existing HMLT configurations with known pile depth creates an absence of field data needed to adequately train an ML algorithm. However, we demonstrate that the use of FEM simulations as proxy training data for the ML algorithms leads to a robust data interpretation scheme.

POWOJENNA ODBUDOWA ZAMKU KSĄŻĄT GRYFITÓW POMORSKICH W SZCZECINIE

Rebuilt in the years 1958-1980 in the Renaissance style with elements of Gothic, the Castle of the Pomeranian Dukes from the Griffin dynasty in Szczecin is located on a promontory of the high western escarpment of the Odra river valley, within the non-existent medieval perimeter walls of the city, in the area of today's Rycerska, Kuśnierska, Mściwoja and so-called Castle Route. Below the castle, there is a partly rebuilt lower town called Podzamcze. Reconstructed in Renaissance forms, the castle is one of the archaeologically and architecturally well-recognized objects of the Duchy of Gryfit. Szczecin's medieval Old Town was almost completely destroyed during American and British air raids on the Szczecin ship base in 1942. It caused the greatest destruction in the history of the Old Town and the castle located in its immediate vicinity. The degree of destruction of the Szczecin castle after the war, as well as the entire Old Town, was estimated at 85%. No elements of the interior furnishings of the castle have survived, except for individual pieces of furniture stored in the cellars. Valuable paneling and wooden furnishings were burnt down in a fire that lasted for many days after the bombing. The preserved buildings were completely unknown to Poles, not related to Polish tradition and history, so it was considered whether they should not be completely demolished, and the area cleared of rubble should be used for new buildings. This is what happened to a large part of the Old Town, where only a few buildings have survived, the technical condition of which allowed their further use. The reconstruction of the castle began in 1956 and was basically completed in 1985, taking into account new program elements, allocating the rooms of the castle, mainly for cultural purposes. In order to preserve the historic character of the building, scientific and conservation supervision over the reconstruction of the castle was carried out by art historians: Dr. Henryk Dziurla from Wrocław (until 1960) and residents of Szczecin: Dr. Zbigniew Radacki in the years 1960-1984 and Krystyna Kroman after 1984. A multi-stage renovation of the former duke's castle was started in 2005, combined with the modernization and change of the technical equipment of the rooms. The unknown stone foundations dating back to the 12th century were discovered under the main courtyard of the Pomeranian Dukes' Castle in 2012.

Performance of Impulse Response Testing on Prismatic Members with Intermediate Joints

Nondestructive Testing (NDT) methods have extensively been used to assess the conditions of civil infrastructure in the recent decades. Among various NDT techniques, Impulse Response (IR) has a vast application due to its simplicity and low cost. However, factors such as reflections from changes in impedance along the investigated members can adversely influence the success of the method. Numerous numerical and experimental studies have already been performed to evaluate the effect of change in mechanical impedances such as bulging, necking and similar anomalies. In this study, the effect of the presence of joints connecting the investigated members to other members, as another source of impedance change, is demonstrated. A three-story steel-concrete composite column of a building was selected for testing and IR tests were conducted. The obtained mobility graphs were clear, and the height of the column was easily measured with an acceptable error. The results of this study show that although the joints located between the top and bottom of the tested member are sources of change in mechanical impedance, they do not result in concealing the resonant frequencies from the wave reflected from the bottom of the member. Thus, IR method seems to be applicable in determining the length of prismatic members with intermediate joints such as piles of unknown bridge foundations with bracing and columns of buried buildings.

Field Evaluation of Load Bearing Capacity and Embedment Depth of Existing Ballastless Plate Girder Bridge Foundations

The ballastless plate girder bridge, classified as a structure type that requires an emergent replacement among domestic railway bridges, generally tends to upgrade to a ballasted track along with continuous welded rail (CWR). The axial forces of the CWR due to the temperature change need to be distributed to the bridge foundations. Because most of the existing ballastless plate girder bridges of over 50 years of age do not provide any design information, such bridge foundations are regarded as unknown foundations, and therefore, it is crucial to identify the structural adequacy and dimension. In this study, an effort was made to establish a correlation between the standard penetration test (SPT) and mid-size pneumatic cone penetration test (MPCP) to estimate the load bearing capacity of an unknown foundation. A field test was conducted to estimate the depth of the unknown foundation by employing SPT and MPCP as the source wave part. The magnitude of the shear wave was mitigated by the presence of PVC and steel pipes, such that it might be possible to identify the embedment depth of unknown foundations.

Limitations of Sonic Echo Testing on Buried Piles of Unknown Bridge Foundations

ABSTRACT Nondestructive Sonic Echo (SE) field tests have shown that this method does not have a satisfactory performance in determining the depth of piles fully buried underneath pile caps. In the current study, we endeavored to investigate the possibility of improving SE methodology to obtain interpretable results leading to determining the depth of buried piles in such foundations. The results obtained from the investigated numerical models indicated that the location of the pile toe could be determined when the height of the pile cap is less than 1 m. However, this value is questionable since it has been concluded in the absence of surrounding soil damping. In real bridge foundations with surrounding soils, the SE method may only be able to detect the length of a pile located beneath a cap with a height significantly smaller than 1 m. In summary, our simplified models show that the SE test is not a proper method to determine the length of fully buried piles supporting caps due to the limitations and difficulties discussed in the article.

Effect of Source Application on Sonic Echo/Impulse Response Tests Applied to Steel H-Piles

AbstractThe sonic echo/impulse response (SE/IR) method is a versatile nondestructive method for evaluating the conditions of unknown bridge foundations. Previous studies have shown that the method ...

Study of the Effect of Source Application on Sonic Echo Tests in Timber Piles

The long-term effects of scour have been identified as one of the primary reasons for bridge failure. To evaluate the performance of the bridges against scour, it is essential to assess the conditions of the bridge foundation including the depth of the piles. Sonic Echo (SE) has been a favorable nondestructive method to evaluate the condition of unknown bridge foundations in the recent decades. Previous studies have shown that the results obtained from SE tests can be affected by a variety of factors such as the pile-to-soil stiffness ratio, length-to-diameter ratio of the pile, presence of defects and anomalies near the pile head, striking method, and hammer type. Although previous studies have discussed such affecting factors, there is a lack of comprehensive investigation regarding the effect of striking method and hammer tip type specific to wood piles supporting bridge decks. In the current study, the effect of striking method and hammer type on the success of SE tests conducted on wood piles has been scrutinized by investigating various options of striking methods and hammer tip types. After comparing different options, superior ones were identified and recommendations for better conducting the SE tests on unknown wood bridge foundations were presented. Numerical simulations were also performed to support some of the conclusions.

Large-scale model test for detecting pile defects using the parallel seismic method

Although the parallel seismic (PS) method has been successfully applied to determine the unknown foundation depth of buildings and bridges, the ability to detect defects in pile foundations has not been verified. In this paper, three large-scale model piles with artificial defects are designed and constructed in multilayered ground. The capability of cross-hole sonic logging, low-strain pile integrity testing and PS method to detect the defects of pile foundation is compared. The effects of the pile-to-borehole distance and the excitation position on the stress wave transmission are analyzed in detail. Finally, the abnormal characteristics of stress waves corresponding to different types of defects are summarized. The results show that pile defects affect the difference in the stress wave impedance by the PS test, and the features of the first arrival waves can reflect the type of defect. When the distance between the borehole and pile is within 0.5 m, the wave form and amplitude of the first arrival waves can be used to distinguish the defects of necking, breaking and sedimentation. Increasing the pile-to-borehole distance by more than 1 m is not conducive to identifying defects. When the pile defect position is close to the side of the shortest path of stress wave transmission, the abnormal characteristics of the first arrival waves are much clearer than when the defect position is far from the side; otherwise, the feature of the defects will be greatly weakened.

Accuracy of Parallel Seismic Test Performance on Steel H-Piles in Layered Soils

AbstractParallel Seismic (PS) method is a straightforward Nondestructive Testing (NDT) method capable of providing valuable information of unknown bridge foundations made of various common construc...

Probabilistic Evaluation of Unknown Foundations for Scour Susceptible Bridges

Abstract By 2005, approximately 60,000 bridges throughout the US were identified as having unknown foundations. The Federal Highway Administration (FHWA) required Departments of Transportation (DOT...

A LSTM surrogate modelling approach for caisson foundations

This study proposes a hybrid surrogate modelling approach with the integration of deep learning algorithm long short-term memory (LSTM) to identify the mechanical responses of caisson foundations in marine soils. The LSTM based surrogate model is first trained based on limited results generated from the SPH-SIMSAND based numerical simulations with a strong validation, thereafter it is applied to predict the mechanical responses of soil-structure interaction and the failure envelope of unknown caisson foundations with various specifications as testing. The results indicate that the LSTM based model is more flexible than macro-element method, because it can directly learn the failure mechanism of caisson foundation from the raw data, meanwhile guarantees a high computational efficiency and accuracy in comparison with physical and numerical modelling. LSTM based surrogated model shows a great potential of application in engineering practice.

Exploratory Study of Nondestructive Parallel Seismic Testing Challenges in Estimating the Depth of Unknown Wood Bridge Foundations

AbstractNondestructive methods have been extensively used to characterize unknown bridge foundations. Among various nondestructive methods, conventional and reverse parallel seismic (PS) methods ar...

Performance of Nondestructive Sonic Echo Testing Method on Partially Dismantled Unknown Wood Bridge Foundations; A Case Study

Sonic Echo (SE) testing method is a well-known, versatile method to gather information pertaining to unknown bridge foundations. Many studies on the applicability and methodology improvement of SE tests to evaluate individual piles and foundations supporting the superstructure have been reported previously. However, there is a rare opportunity for obtaining the performance of SE tests without the bridge deck. In the current study, three piles of a dismantled unknown bridge foundation were tested. Unusual vibrations on velocity signals were found which are independent of the location of the sensors. Such signals do not contain identifiable echoes from the pile toe. Therefore, they cannot be used to determine the depth of the piles. The results and observations of this study show that there is little future application for conducting SE tests on bridges that are out of service.

Site and building characterization of the Orvieto Cathedral (Umbria, Central Italy) by electrical resistivity tomography and single-station ambient vibration measurements

A multidisciplinary approach based on the integration of geological and in situ geophysical techniques was applied to investigate the Orvieto Cathedral (Umbria, Central Italy) and the underlying subsurface. Notwithstanding this Cathedral has successfully survived different earthquakes occurred in the region, it shows some signs of damage that arise uncertainties about its safety under future seismic events. In order to investigate its unknown foundation geometry, to reconstruct the geological setting and to characterize from a static and dynamic point of view the site-structure system, geological investigations together with electrical resistivity tomography and horizontal-to-vertical spectral ratio analysis of single-station ambient vibration recordings were carried out. The exploitation of these two different geophysical techniques allowed us (1) to delineate the unknown foundation geometry of the Orvieto Cathedral, (2) to estimate the main resonance frequencies of the Cathedral and (3) of the Orvieto site, and (4) to retrieve information about its deep subsurface engineering-geological structure.

Evaluation of Unknown Bridge Foundations Using Borehole-based Nondestructive Testing Methods: A Case Study in Urban Settings

There are a significant number of bridges for which information regarding the foundation is missing or incomplete. It is extremely challenging to evaluate the performance of such unknown foundation bridges (UFB), particularly against scour or when their foundations are reused. For critical UFB, it is often necessary to estimate performance by developing an appropriate working model of subsurface foundation conditions. Typically, nondestructive testing (NDT) has served as the most viable alternative due to the costs and risk associated with excavation, coring, and probing. NDT can be quite difficult to perform and their results can contain significant uncertainty in highly urban settings. The primary objective of this study was therefore to compare performance of borehole NDT methods when evaluating the depth of two in-service unknown foundations (concrete-filled steel pipe piles and H-piles) in highly urban settings. The borehole magnetic, parallel seismic, borehole sonic, and borehole radar methods were implemented to determine the foundation bottom locations. Though uncertainty was present in all measurements, the borehole magnetometer and radar results proved the most conclusive. Parallel seismic testing did not yield any evidence of foundations due to issues with background noise and lack of direct access to the foundation. Likewise, borehole sonic testing was generally inconclusive due to issues with sensor directivity and attenuation. Borehole magnetometer estimated the depth to the foundation bottom as 8.6 m and 9.2 m at the two sites. Borehole radar estimates for the depth to foundation bottom compared favorably at 9.8 m and 8.0 m for the two sites. Given the borehole construction and depth to competent rock at the sites, these results for borehole magnetometer and radar were likely a minimum estimate for the location of the foundation bottoms. Such information can help evaluate long-term performance of this system as part of rehabilitation and reuse efforts.

Nondestructive Method for Length Estimation of Pile Foundations Through Effective Dispersion Analysis of Reflections

Motivated by the important problem of unknown foundations, a nondestructive evaluation technique, named effective dispersion analysis of reflections (EDAR), is developed for estimating embedded depth of pile foundations. EDAR testing involves laterally exciting the pile with the hammer and measuring the accelerations at two other points on the pile. The novelty of EDAR comes from the processing these signals; unlike existing methods, EDAR accurately captures the effect of physical dispersion of the waves as they propagate in the pile, and the reflections from the pile tip. The key to data processing is the EDAR plot, which is a plot of phase difference between the two responses as a function of newly introduced effective wavenumber that encapsulates the wave dispersion characteristics. The methodology is easy to use in that a simple formula can convert the oscillatory characteristics of EDAR plot to the unknown embedded depth. This paper contains the derivation of the underlying formulation followed by verification with synthetic models and validation in laboratory settings, resulting in less than 5% error in embedded length.