Papers by Bhagya Jayasinghe
Shock Environment Assessment of Underground Arch–Wall Structures Subjected to Ground Shock
Journal of Engineering Mechanics
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Rock Mechanics and Rock Engineering in Singapore
Performance of Pile Groups Subjected to Surface Explosion
Ground vibrations from blasting are undesirable and they are very short in duration with high pri... more Ground vibrations from blasting are undesirable and they are very short in duration with high principal frequencies and high amplitude. Structural response to that kind of excitations may differ significantly from that generated by lower-frequency earthquake vibrations. In practice, the damage to nearby structures to generated ground vibrations has been controlled by various codes and regulations available. However, the existing vibrations limits are not always applicable, as they depend on the geological conditions of the site and the dynamic characteristics of the structure. This paper investigated the influence of the rock-soil interface on the response of pile foundation to ground-borne vibration from rock blasting, through numerical simulations using finite element software LS-DYNA. It is found that the slope of the rock-soil interface greatly influences the location of damage and the extent of damage on the pile. The bottom of the pile is subjected to a larger blast pressure a...
Construction and Building Materials, 2021
This research is carried out to investigate the Gaussian process regression (GPR) based on a mach... more This research is carried out to investigate the Gaussian process regression (GPR) based on a machine learning model to predict the compressive strength of Miscanthus lightweight concrete (MLWC). A database of 414 experimental data, which includes nine input variables such as six mix constituents of concrete, form of specimen, curing time and pre-treatment condition and an output variable of compressive strength of MLWC, is constructed from the data collected by a series of experimental tests on MLWC. Two kernel functions, namely, the squared exponential and rational quadratic are used in the GPR model. It is found from experiments that the GPR model with rational quadratic kernel gives minimum errors for predicting compressive strength of MLWC. In addition, a user-friendly graphical user interface is created using MATLAB software to deploy the GPR model which can be used at an early stage of designing the Miscanthus concrete members instead of using costly experimental investigation.
Computers and Geotechnics, 2019
This paper presents a 3D coupled Smoothed Particle Hydrodynamics (SPH) and Finite Element Method ... more This paper presents a 3D coupled Smoothed Particle Hydrodynamics (SPH) and Finite Element Method (FEM) model, which was developed to investigate the extent of damage zone and fracture patterns in rock due to blasting. The RHT material model was used to simulate the blasting-induced damage in rock. The effects of discontinuity persistence and high in-situ stresses on the evolution of blasting-induced damage were investigated. Results of this study indicate that discontinuity persistence and spatial distribution of rock bridges have a significant influence on the evolution of blasting-induced damage. Furthermore, high in-situ stresses also have a significant influence on the propagation of blasting-induced fractures, as well as the patterns of fracture networks. It is also shown that the blasting-induced cracks are often induced along the direction of the applied high initial stresses. Moreover, additional cracks are normally generated at the edges of the rock bridges probably due to the relatively high stress concentration.
Theoretical and Applied Fracture Mechanics, 2019
A complete understanding of the fracture behaviour of anisotropic rocks under elevated temperatur... more A complete understanding of the fracture behaviour of anisotropic rocks under elevated temperatures is fundamentally important for rock and reservoir engineering applications. This paper shows a three-dimensional numerical investigation of the fracture behaviour of anisotropic sandstone, with consideration of the effects of temperature and material anisotropy. In the study, a 3D semi-circular bend (SCB) model was established by using the Discrete Element Method (DEM). The thermal responses of different minerals and the strength anisotropy of incipient bedding planes were considered in the model. The DEM model was calibrated against a series of laboratory experiments on Midgley Grit sandstone (MGS) that exhibits intrinsic anisotropy. The pure mode I, mode II, and mixed-mode (I+II) fracture characteristics of the MGS were investigated under elevated temperatures (up to 600°C) using the established DEM model. The thermal degradation (i.e., fracturing) of the rock, the fracture load, the evolution of micro-cracks, and the stress-strain relationship around notch tips were analysed, with emphasis on enlightening the micro-mechanisms underlying the fracture behaviour. The results of the study were discussed and then compared with experimental observations and theoretical predictions.
International Journal of Rock Mechanics and Mining Sciences, 2018
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 Intern... more This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International licence Newcastle University ePrints-eprint.ncl.ac.uk Gui YL, Zhao ZY, Jayasinghe LB, Zhou HY, Goh ATC, Tao M. Blast wave induced spatial variation of ground vibration considering field geological conditions.
Soil Dynamics and Earthquake Engineering, 2018
A series of field tests using controlled blasting was conducted at a location in the North Wester... more A series of field tests using controlled blasting was conducted at a location in the North Western part of Singapore to assess the behaviour of pile foundations subjected to ground excitation. The field tests involved three piles with different pile head fixity conditions. The piles were instrumented with strain gauges to evaluate the bending moments and axial force along the piles. For the fixed-head piles, the maximum bending moment occurred at the pile head level. For free-head pile exhibited higher bending moments close to the mid-height of the pile and zero bending moment at the pile head due to the absence of restraints at the top. For all cases, the axial force was maximum value at the pile head.
Procedia Engineering, 2017
As the free field geological condition is usually complex, the conventional wave attenuation law ... more As the free field geological condition is usually complex, the conventional wave attenuation law established for the homogeneous open field may not be applicable for actual field situations. Thus, to understand the impact of the attenuation law and the geological features on the blast wave propagation, a field rock blasting test is conducted and the ground vibration is carefully monitored. To better understand the phenomenon, a numerical model considering the field geological features is established using the finite difference method. The field test results are then used to calibrate the numerical model. From the calibration, the parameters involved in the general form of peak particle velocity have been determined. It is demonstrated that the blast wave propagation in the free field is significantly governed by the field geological conditions, especially the interface between rock and soil layers.
Computers and Geotechnics, 2017
Blasting has been widely used in mining and construction industries for rock breaking. Ground vib... more Blasting has been widely used in mining and construction industries for rock breaking. Ground vibration induced by blasting is an inevitable side effect that may cause damage to nearby structures, if not properly controlled. In this study, response and possible damage of rock-socketed pile near soil-rock interface subjected to ground shock excitations are investigated and quantified with coupled SPH-FEM method. Results indicate that the base of the pile is relatively vulnerable and that the soil properties significantly influence on response of pile subjected to a specific blast load. Furthermore, based on the numerical results, ground vibration attenuation equation is proposed.
Structural Engineering International, 2014
This paper develops and presents a fully coupled nonlinear finite element (FE) procedure to treat... more This paper develops and presents a fully coupled nonlinear finite element (FE) procedure to treat the response of piles to ground shocks induced by underground explosions. The Arbitrary Lagrange Euler coupling formulation is used in the study with proper state material parameters and equations. Pile responses in four different soil types, viz, saturated soil, partially saturated soil, and loose and dense dry soils are investigated and the results compared. Numerical results are validated by comparing them with those from a standard design manual. Blast wave propagation in soils, horizontal pile deformations, and damages in the pile are presented. Pile damage presented through plastic strain diagrams will enable vulnerability assessment of the piles under the blast scenarios considered. The numerical results indicate that the blast performance of single pile foundations embedded in saturated soil and loose dry soil are more severe than those embedded in partially saturated soil and dense dry soil. The present findings can serve as a benchmark reference for future analysis and design.
Blast response and failure analysis of pile foundations subjected to surface explosion
Engineering Failure Analysis, 2014
ABSTRACT This paper presents the response of pile foundations to ground shocks induced by surface... more ABSTRACT This paper presents the response of pile foundations to ground shocks induced by surface explosion using fully coupled and non-linear dynamic computer simulation techniques together with different material models for the explosive, air, soil and pile. It uses the Arbitrary Lagrange Euler coupling formulation with proper state material parameters and equations. Blast wave propagation in soil, horizontal pile deformation and pile damage are presented to facilitate failure evaluation of piles. Effects of end restraint of pile head and the number and spacing of piles within a group on their blast response and potential failure are investigated. The techniques developed and applied in this paper and its findings provide valuable information on the blast response and failure evaluation of piles and will provide guidance in their future analysis and design.
Computers & Structures, 2013
Computer simulation of underground blast response of pile in saturated soil. Computers and Struct... more Computer simulation of underground blast response of pile in saturated soil. Computers and Structures, 120, pp. 86-95.
Computers & Structures, 2014
Pile foundations transfer loads from superstructures to stronger sub soil. Their strength and sta... more Pile foundations transfer loads from superstructures to stronger sub soil. Their strength and stability can hence affect structural safety. This paper treats the response of reinforced concrete pile in saturated sand to a buried explosion. Fully coupled computer simulation techniques are used together with five different material models. Influence of reinforcement on pile response is investigated and important safety parameters of horizontal deformations and tensile stresses in the pile are evaluated. Results indicate that adequate longitudinal reinforcement and proper detailing of transverse reinforcement can reduce pile damage. Present findings can serve as a benchmark reference for future analysis and design.
Due to increased number of terrorist attacks in recent years, loads induced by explosions need to... more Due to increased number of terrorist attacks in recent years, loads induced by explosions need to be incorporated in building designs. For safer performance of a structure, its foundation should have sufficient strength and stability. Therefore, prior to any reconstruction or rehabilitation of a building subjected to blast, it is important to examine adverse effects on the foundation caused by blast induced ground shocks. This paper evaluates the effects of a buried explosion on a pile foundation. It treats the dynamic response of the pile in saturated sand, using explicit dynamic nonlinear finite element software LS-DYNA. The blast induced wave propagation in the soil and the horizontal deformation of pile are presented and the results are discussed. Further, a parametric study is carried out to evaluate the effect of varying the explosive shape on the pile response. This information can be used to evaluate the vulnerability of piled foundations to credible blast events as well as ...
Nonlinear three-dimensional anisotropic material model for failure analysis of timber
Engineering Failure Analysis
IPTEK Journal of Proceedings Series
Pile foundations are commonly used as foundation systems for high-rise buildings and bridges. T... more Pile foundations are commonly used as foundation systems for high-rise buildings and bridges. This paper uses a fully coupled three dimensional numerical modelling procedure to study the performance of pile foundations subjected to ground shocks induced by surface explosions. The comprehensive numerical model includes the pile, surrounding soil, air and the explosive. Appropriate material models are incorporated and dynamic non-linear analysis is carried out using finite element techniques. The soil in which the pile is buried could influence the blast performance of the pile. A parametric study is hence carried out to evaluate the effects of soil properties of density, friction angle, cohesion and Poisson's ratio on the blast performance of the pile. It is found that density and cohesion of soil have significant effects on the deflection of the pile under blast loading. Poisson's ratio has some effect, but effect of the soil friction angle is not very significant. The findings of this study will serve as a benchmark reference for future analysis and design of pile foundations to blast loading.
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Papers by Bhagya Jayasinghe