Yu-Hsing Wang

• Doctor of Philosophy
• Professor (Full) at Hong Kong University of Science and Technology

This paper was published at the 10th International Conference on Innovative Production and Construction (IPC 2024), Perth, Australia. https://ipcannual.com/proceedings/

A prestigious journal, Information Fusion, has accepted this paper after nearly one year! Project page: http://zl-he.com/Generative-BIM Code link: https://github.com/hzlbbfrog/Generative-BIM

Cracks pose safety risks to infrastructure and cannot be overlooked. The prevailing structures in existing crack segmentation networks predominantly consist of CNNs or Transformers. However, CNNs exhibit a deficiency in global modeling capability, hindering the representation to entire crack features. Transformers can capture long-range dependencie...

Intelligent structural design using AI can effectively reduce time overhead and increase efficiency. It has great potential to become the new design paradigm in the future to assist and even replace human engineers, and therefore it has become a research hotspot in the academic community. However, current methods have some limitations to be address...

Cracks provide an essential indicator of infrastructure performance degradation, and achieving high-precision pixel-level crack segmentation is an issue of concern. Unlike the common research paradigms that adopt novel artificial intelligence (AI) methods directly, this paper examines the inherent characteristics of cracks so as to introduce bounda...

This study examines the mechanical energy comprising the sum of kinetic energy and potential energy for improving understanding of tree dynamics under free vibration. Two methods are proposed to reconstruct the mechanical energy by means of trees’ motion and dynamic properties measured by a multi-beam flash light detection and ranging (LiDAR) senso...

In this study, biaxial shear and creep numerical simulations were carried out on both dense and loose sands based on discrete element method to examine the kinematics and micro mechanism of creep. The simulations qualitatively reproduced the macroscopic behavior of sand during shearing and creep. Contact forces, contact normals and voids were used...

This study presents a new landslide monitoring system, which is designed to be cost-effective, robust, flexible, and scalable, aiming for long-term and real-time monitoring and large-scale deployment in harsh and remote environments. This wireless monitoring system consists of the hybrid sensor node (including the GNSS receiver and MEMS acceleromet...

Measuring the three-dimensional motion of trees at every position remains challenging as it requires dynamic measurement technology with sufficient spatial and temporal resolution. Consequently, this study explores the use of a novel multi-beam flash light detection and ranging (LiDAR) sensor to tackle such a sensing barrier. A framework is propose...

Two research studies have been implemented to explore the potential of applying artificial intelligence (AI) technologies in works projects and maintenance work of the Drainage Services Department (DSD) for enhancing the efficiency related to environmental monitoring and structural inspection, referred to as the AIEIA and AIBIM projects, respective...

This study explored the deformation mechanisms and, in particular, the features of particle pair motions in response to shearing. A specially designed biaxial testing system with a flexible boundary equipped with an image system was set up for experimental tests. The whole testing system was modified from a CKC triaxial testing system. The particle...

In the study, biaxial shearing tests were carried out through the numerical simulations based on the discrete element method to examine the correlation of macro deformation and micro kinematics characterization in contact scale. The contact motions were decomposed into three independent types, i.e., contact deformation, contact rolling and rigid-bo...

This paper presents a framework for automated defect inspection of the concrete structures, made up of data collection, defect detection, scene reconstruction, defect assessment and data integration stages. A mobile data collection system, comprising a 360° camera and a digital Light Detection and Ranging (LiDAR), is developed to render high flexib...

This paper reports the innovative development of a flexible, multiple-layer, economical but robust, and automated high-speed shear wave (Vs) tomographic control and data acquisition system for process monitoring in the laboratory and the associated validation for monitoring the dynamic process of model pile installation. This tailor-made tomographi...

In this work, we propose a novel two-stage framework for the efficient 3D point cloud object detection. Instead of transforming point clouds into 2D bird eye view projections, we parse the raw point cloud data directly in the 3D space yet achieve impressive efficiency and accuracy. To achieve this goal, we propose dynamic voxelization, a method tha...

This paper reports the use of the deep learning-based technique to characterize the particle orientation of clay samples. The U-Net model was applied to perform semantic segmentation for identifying individual kaolinite particles, based on the scanning electron microscopic images taken from clay samples subjected to 1-D consolidation. The measurabl...

Automatic bird detection in ornithological analyses is limited by the accuracy of existing models, due to the lack of training data and the difficulties in extracting the fine-grained features required to distinguish bird species. Here we apply the domain randomization strategy to enhance the accuracy of the deep learning models in bird detection....

In this study, numerical simulations by the discrete element method were carried out to examine the characteristics of energy dissipation in sand. In the simulations of static biaxial tests of loose and dense samples, it was found that the applied boundary work is either stored in the strain energy or dissipated through interparticle friction when...

Inspection of civil infrastructure is a major challenge to engineers due to the limitations in existing practice, which are as laborious, time-consuming and prone to error. To address these issues, we have applied deep learning for image-based inspection of concrete defects of civil infrastructure, and have established an artificial intelligence-em...

This paper reports a feasible alternative to compile a landslide inventory map (LIM) from remote sensing datasets using the application of an artificial intelligence–driven methodology. A deep convolutional neural network model, called LanDCNN, was developed to generate segmentation maps of landslides, and its performance was compared with the benc...

This study provides experimental evidence of the correlation between different fabric tensors in 2D granular assemblies subjected to shearing. Two testing assemblies with different elliptical rods were used and the shearing tests were conducted in a tailor-made biaxial cell. Both the rods and cell were produced using the 3D printing technique. Thro...

3D point cloud interpretation is a challenging task due to the randomness and sparsity of the component points. Many of the recently proposed methods like PointNet and PointCNN have been focusing on learning shape descriptions from point coordinates as point-wise input features, which usually involves complicated network architectures. In this work...

In this study, the U-oedometer, a novel modified oedometer cell equipped with tailor-made needle probes, is developed to easily and accurately measure the excess pore water pressure (\(\Delta u\)) during 1D consolidation tests and to determine the coefficient of consolidation (\(c_{\text{v}}\)). The 3D printing technique is applied to make simple y...

This paper reports the application of deep learning for implementing the anomaly detection of defects on concrete structures, so as to facilitate the visual inspection of civil infrastructure. A convolutional autoencoder was trained as a reconstruction-based model, with the defect-free images, to rapidly and reliably detect defects from the large v...

The dielectric constant of soil is used to estimate its water content in a range of applications. Unlike the widely known effect of water content on the soil dielectric constant (consistent direct proportionality), only a limited number of studies have reported the effects of soil dry density, however, with equivocal results. This paper, therefore,...

Discriminator from generative adversarial nets (GAN) has been used by some research as feature extractor in transfer learning and worked well. But there are also some studies believed that this is a wrong research direction because intuitively the task of discriminator focuses on separating the real samples from the generated ones, making the featu...

This study explored the characteristics of local responses in 2D assemblies of elliptical particles when subjected to shearing. A biaxial shearing system was designed for this investigation, and two assemblies of elliptical rods with different eccentricities were used. To quantify the local responses, the assemblies were partitioned into individual...

This study reports model pile tests designed to characterize the underlying mechanisms of driven pile setup in dry sand by means of stress measurement with the tactile pressure sensors and spatio-temporal, shear-wave velocity (Vs) distributions using an automated high-speed tomographic imaging system. The pile-load test results demonstrate a distin...

In this study, an innovative experimental setup for model pile tests was developed to characterize friction fatigue in sand during cyclic jacking. In the experimental setup, a high-performance precision electric linear actuator was used to control jacking of the model piles. P-wave tomographic imaging was used to characterize the associated changes...

This paper describes a microstructural characterizations of high-quality, load-preserved fabric 1-D consolidated kaolinite samples, which covers from the beginning stage of clay sample preparation to the final stage of the microstructural analyses. To achieve this goal, a tailor-made oedometer is produced using the 3-D printing technique. First, a...

This paper reports the density effect on the aging-induced increase in soil stiffness based on discrete-element method (DEM) simulations conducted on dense, medium-dense, and loose samples for the study. Like experimental observations, among the three investigated, the medium-dense sample showed the highest aging rate in terms of the increase in th...

In this paper, through micromechanical analyses, the microstructural responses of kaolinite samples subjected to 1-D consolidation were quantitatively analyzed. Using a tailor-made, 3D-printed oedometer in preparing samples subjected to different loading levels, the applied loading was maintained during the freezing process of the sample in order t...

In this study, a novel method for pore network extraction in the weakly consolidated media is reported, which unifies both the Delaunay tessellation (DT) and maximal ball (MB) methods in a complementary way. This unified method retains the advantages of both methods, and most importantly, eliminates the disadvantages when either the DT or the MB me...

This paper describes the mechanical behavior of artificially cemented sands with strong, intermediate, and weak bond strengths, using experimentation and 3D discrete element method (DEM) simulation. The focus is on the features of bond breakage and the associated influences on the stress–strain responses. Under triaxial shearing, the acoustic emiss...

High-quality samples are always critical in the meaningful microstructural characterizations of clay. A practical guide, together with a real sample tested as an example, is therefore proposed in this study, aiming to prepare high-quality load-preserved fabric clay samples subjected to 1-D consolidation for the pore size and fabric characterization...

Electrical resistivity is often utilized to estimate different flow-related properties of unsaturated soils, such as hydraulic conductivity. To be better utilized for such a purpose, the electrical resistivity anisotropy has to be characterized to account for the anisotropic nature of soils. Thus, a testing cell equipped with two individual four-pr...

This paper aims at establishing the predictive capability of the discrete element method (DEM) by validating the simulated responses of granular systems against experimental observations at both the macroscale and the microscale. A previously published biaxial shearing test on a 2D assembly of randomly packed elliptical rods was chosen as the bench...

This paper aims to bridge the soil properties and the soil response in the discrete element method (DEM) simulation using the artificial neural network (ANN). The network was designed to output the stress-strain-volumetric response from inputting the soil properties. 31 biaxial shearing tests with varying soil parameters were generated using the DE...

The anisotropy of granular media and its evolution during shearing are important aspects required in developing physics-based constitutive models in Earth sciences. The development of relationships between geoelectrical properties and the deformation of porous media has applications to the monitoring of faulting and landslides. However, such relati...

In this study, the economical FlexiForce sensor, which is thin and flexible, was used to measure Ko and the excess pore water pressure during a 1D consolidation test on kaolinite clay samples. Before the sensor could be used in the measurement, a special waterproof coating was applied, after which sensor calibration was carried out. The coated Flex...

Aging- or creep-related phenomena in sand have been widely studied, and the discrete element method (DEM) has been frequently used to model the associated soil behavior and then to explore the associated underlying mechanisms. However, several difficulties involved in modeling still remain unsolved. To resolve these difficulties, a new approach bas...

Vegetation essentially has both beneficial and detrimental hydrological effects on slope stability, and the balance between these effects changes throughout the year. For engineers considering vegetation as an ecotechnological solution to slope instability, it is therefore necessary to understand how the net hydrological effect varies with local we...

This study explored the features of particle motion and, in particular, the associated movements at contacts in response to direct shearing. A tailor-made direct shear box equipped with an image system was set up. The particle image velocimetry (PIV) technique and close-range photogrammetry were used together to help with the investigation. The tes...

This study presented the details of a specially designed biaxial testing system with a flexible boundary to examine the features of particle motion and associated contact movement during shearing. The whole testing system was modified from a CKC triaxial testing system so that the production cost was low, and this approach was applicable to other t...

As global warming brings forth extreme precipitation in the typhoon-prone region in Asia, e.g. Hong Kong, Taiwan and Japan, the need for a scalable and yet accurate landslide sensing system becomes increasingly urgent. Natural slopes are the focus since their failures are often large-scale and disastrous; however, it is extremely expensive to monit...

In this paper, the responses of kaolinite samples with two different soil structures, i.e., unwashed and pH 7.8 samples, under 1-D consolidation, isotropic loading–unloading and triaxial shearing are examined. The focus is on the associated changes in the pore-size distribution. During isotropic consolidation, the unwashed sample, with an open, agg...

This paper aims to provide a comprehensive picture of the sand responses during secondary compression and rebound based on experimental characterizations. The experiment was carried out on dry Leighton Buzzard sand using a modified direct shear box equipped with tactile pressure sensors for the stress measurements and bender elements for stiffness...

The shrinkage curve provides information of value for the interpretation of soil-water characteristic curve data. However, there is need for an accurate and precise volume measurement technique during the shrinkage test. This paper presented an inexpensive automated digital image processing technique, which allowed accurate and precise measurements...

This paper reports the experimental findings regarding the influence of fines on the stiffness reduction, the stiffness anisotropy, and the stiffness changes (during aging) of Toyoura sand and kaolinite (fines) mixtures. The fines content of the mixture samples ranged from 0% to 30% by weight. A tailor-made true triaxial apparatus was used and equi...

Sands age and their engineering properties often improve significantly during performance life cycles and are of practical interest to engineers. Although various hypothesized aging mechanisms have been proposed, experimental evidences identifying the underlying mechanisms have not yet been provided. The experiment of this study, using a true triax...

Fines influences on the stiffness of sand with inherent fabric anisotropy

Understanding the soil responses during monotonic jacking can help improve the estimation of axial capacity in pile foundation design. To examine the soil responses in terms of strain and stress distributions, stress paths, the movement of particles and contact force mobilization during monotonic jacking, a three-dimensional simulation of a centrif...

Static and dynamic liquefaction may produce different levels of damages on the infrastructures and various numbers of casualties. Understanding the associated initiation mechanisms therefore is very important for geotechnical engineers to predict and manage the relevant hazards. In this study, a series of DEM simulations of undrained triaxial compr...

In this study, model pile tests were carried out in a custom-made pressurized chamber to explore the mechanisms of a driven pile setup in dry sand. A bender element system and tactile pressure sensors were used in parallel to monitor the stiffness and stress changes in the soil surrounding the pile during the test. The experimental results demonstr...

Statistical models have been widely used in soil science, hydrogeology and geotechnical engineering to predict the hydraulic conductivity of unsaturated soils. However, no effective method is available yet for the determination of the associated model parameters such as the tortuosity factor q. Considering the analogy between water flow and electri...

In this study, DEM simulations of triaxial creep tests on dense and loose sand samples were carried out to examine the micromechanics involved during creep. The simulated creep responses reproduce qualitatively the published experimental results. During the primary creep, the creep stress is gradually borne by the contact normal forces instead of c...

Rainfall-induced landslides are on the rise due to global warming but the associated initiation mechanisms remain unclear. To observe the local initiation features of flow landslides under different rates of water supply, a well-instrumented flume capable of tightly controlling the inflow from the groundwater supply pipes and upstream discharge was...

The electrical resistivity survey, traditionally realized by the direct current (DC) resistivity method, has shown great value for charactering vadose zone dynamics. Compared with the DC resistivity method, the capacitively coupled (CC) resistivity method has a higher ratio of measurement speed to data density, and thus is economically preferred fo...

The capacitively coupled resistivity method using line antennas (or electrodes) has been widely applied for various kinds of applications. To solve the associated inversion problem, the general practice (i.e., the indirect inversion method) for 2D surface resistivity surveys is to approximate the line-electrode array by an equivalent point-electrod...

This paper reports K0 of dry sand in response to different loading conditions and under secondary compression. The experiments were carried out using an oedometer and tactile pressure sensors were used to measure the horizontal stress for K0 calculations. During loading, K0 remains a constant as the vertical stress σ′v increases. The corresponding...

As global warming is altering the environment and precipitation patterns, the situation calls for small, low-cost, and accurate sensors in large deployment scale to monitor hazardous natural terrains such as slopes and essential infrastructures at risk. Advancement of technologies in the past decade offers us MEMS (micro-electromechanical systems)...

In this paper, experimental studies were conducted using a tailor-made oedometer equipped with a bender element system and tactile pressure sensors to examine the behavior and mechanisms of structuration in sand under the [TEX equation: \hbox {K}_{0}] condition. Numerical simulations based on the discrete element method (DEM) were also carried out...

In this study, the nonlinear, Hertz–Mindlin contact model and clumped particles were used in the discrete element method simulations of cyclic shear tests to obtain the shear modulus G and damping ratio D at a wide range of strain levels. The simulated G and D, which demonstrated similar behavior as observed by the experiments, can be derived from...

In this paper, experiments and discrete element method (DEM) simulations were conducted in parallel to examine the underlying mechanisms of aging effects on the stiffness changes of sand with inherent fabric anisotropy. The true triaxial apparatus, equipped with a bender-element system, was used to monitor the evolution of the small strain shear mo...

The capacitively coupled (CC) resistivity method is an emerging geophysical technique for near-surface investigations. However, there are two major problems associated with using the CC resistivity (line antenna) system in ground investigations. These two problems are (1) the geometrical factor and (2) measurement biases. We first derive the geomet...

This paper provides a method of properly calibrating tactile pressure sensors for the measurement of stress in soils subjected to short-term and long-term static loading. Tailor-made cells were used for the sensor calibration and examination of the calibration accuracy. It was found that if the calibration results for each sensing element on the se...

In this paper, experimental studies were conducted using a true triaxial apparatus with a bender element system to examine the mechanisms of aging-induced, small-strain shear modulus changes in sand samples under isotropic and anisotropic loading. Numerical simulations based on the discrete element method (DEM) were also carried out in parallel. In...

In this study, numerical simulations using the discrete element method (DEM) were performed to examine the evolution of pore characteristics in dense and loose samples subjected to a biaxial creep test. Sliding creep between particle contacts was incorporated in the DEM simulations, which displayed similar creep behavior found in experiments. The i...

In this study on the surface charges and structural characterization of kaolinite clay, it is found that the highly pH dependent edge charges are important to the interparticle forces and associated fabric formations. When the pH is below the isoelectrical point of the edge surfaces, IEPedge, the Coulombian attraction between faces and edges domina...

This paper reports the effects of structure on the mechanical responses of kaolinite with known and controlled fabric associations. The dynamic properties and strength were assessed by resonant column tests and undrained triaxial compression tests, respectively. The experimental results demonstrate that interparticle forces and associated fabric ar...

In this paper, bender elements are used as sensors to measure the damping ratio of soil by the spectral-ratio method. The results of numerical and physical experiments suggest that adequate measurement precision can be achieved by reducing the two types of inherent biases arising from (i) the near-field effect and (ii) the different transfer functi...

An exploratory laboratory study using the miniature 2-axis MEMS (Micro-Electro- Mechanical System) accelerometers and a 3-axis wireless accelerometer to identify landslip characteristics in both sudden and gradual slope failure was carried out in this paper. These miniature sensors in the test were buried into different positions of the slope const...

A wide-frequency dielectric spectrum can provide meaningful information that is intimately related to the properties of soils. A small-sized sensor allows the assessment of local dielectric characteristics of soils and is conducive for long-term monitoring as it can be buried in the soil sample without causing significant perturbations. Considering...

In this study, a raicroelectromechanical systems (MEMS) accelerometer, MEMS A (1-3 kHz), and a commercially available piezoelectric acoustic emission (AE) sensor, PZT (125-750 kHz), were used to capture AE responses in uncemented and cemented sands during triaxial compression tests. The AE rates measured in the cemented sands by both sensors demons...

This study investigates the aging effects on the small-strain shear modulus and damping ratio of sands and offers explanations for the measured results based on the concept of contact-force homogenization. Resonant column tests of aged sands under various aging conditions were conducted. The results show that loose sands exhibit greater aging effec...

The properties of clay-water mixtures are refl ected in their wide-frequency dielectric responses that result from different polarization mechanisms. This feature is useful in various soil science applications but has not been systematically investigated. The objective of this study was to characterize the broadband dielectric spectrum of kaolinite...

In this paper, experimental studies using a true triaxial apparatus and a bender element system, and numerical simulations based on the discrete element method (DEM) were used to investigate the stress- and fabric-induced shear-stiffness anisotropy in soils at small strains. Verified by experiments and DEM simulations, the shear modulus was found t...

In this study, aging in dry, clean sand induced by contact creep is investigated through numerical simulations using the discrete element method. Simulation results demonstrate that contact creep initiates the redistribution of contact forces. Although contact creep produces a very small decrease in porosity (approximately 1.7%), a significant chan...

In this study, the effects of cementation on the stress-dilatancy and strength of cemented sand are investigated through experimental characterizations using triaxial tests and numerical simulations using the discrete element method. At small strains, dilatancy is hindered by the intact bonding network that produces a web-patterned force chain. Aft...

This study investigates the density effect on the aging behavior of sands and explore whether the aging-induced stiffness gain is isotropic by nature. The results of resonant column tests on Ottawa sand samples reveal that the medium-dense sample had the highest aging rate, as determined by its shear-modulus increase, followed by the dense and loos...

A slim-form, open-ended coaxial probe with an outside diameter of 2.2mm was used in this study to take local dielectric measurements in soils. The dielectric relaxation strength of bulk water, w, and the DC conductivity of the saturated sample, mix, are jointly used to characterize the spatial variability of different specimens including glass bead...

In this paper, triaxial tests and numerical simulations using the discrete element method (DEM) are combined to explore the underlying mechanisms of the unique behavior of artificially cemented sands. The experimental results show that strength enhancement, volumetric dilation, and the shear banding associated failure mode are observed in Portland...

In this paper, the sedimentation behavior of two kaolinite samples with distinct fabric associations is characterized using mechanical and electromagnetic wave-based techniques. The two different fabric formations, the edge-to-face (EF) flocculated structure (i.e., Sample A) and the dispersed and deflocculated structure (i.e., Sample B), were produ...

The loss mechanisms responsible for the observed attenuation in soils are often unclear and controversial. This is particularly the case with the small-strain damping D min in air-dry sands. Ultimately, physical explanations must accommodate the observed effects of confinement, strain level, frequency, and load repetition. Three hypotheses are expl...

In this paper, the results of a series of experiments using one-dimensional oedometer testing, mercury intrusion porosimetry (MIP), and scanning electron microscopy are reported on kaolinite samples with known and controlled fabric associations to reexamine the dual-porosity hypothesis for the underlying mechanisms of secondary consolidation. The o...

This paper reconsiders the signals that are transmitted in bender element tests and the associated transfer functions to identify the problems that bias the velocity (travel time) determination. The findings of the numerical and physical experiments show that errors appearing in the velocity estimation can be traced to (1) the near-field effect and...