ORCID Profile
0000-0002-3927-4995
Current Organisation
University of Engineering and Technology
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Publisher: American Society of Civil Engineers (ASCE)
Date: 10-2015
Publisher: Springer Science and Business Media LLC
Date: 19-09-2022
Publisher: American Society of Civil Engineers (ASCE)
Date: 06-2017
Publisher: Springer Science and Business Media LLC
Date: 26-07-2021
Publisher: ASTM International
Date: 07-2016
DOI: 10.1520/GTJ20150288
Publisher: Elsevier BV
Date: 2021
Publisher: Thomas Telford Ltd.
Date: 03-2018
Abstract: This paper outlines an experimental investigation into seepage-induced failures in soils subjected to static and cyclic loading. Internally stable, marginal and unstable soils are characterised by heave, composite heave–piping and suffusion that develops immediately upon instability. In this study, the stable specimens exhibited heave at larger hydraulic gradients than the unstable specimens failing by suffusion at relatively smaller hydraulic gradients. Under no external load (i.e. self-weight only), the relative density (R d ) and particle size distribution (PSD) in tandem controlled the internal stability of soils, although the effective stress magnitude (σ′ vt ) also had a role to play under both static and cyclic loading conditions. Instability in soils was governed by specific combinations of their geo-hydro-mechanical characteristics such as PSD, R d , stress reduction factor, critical hydraulic gradients and associated effective stress levels. These factors are combined to model the development and inception of instability, and the paper offers visual guides as a practical tool for practitioners. Each soil has a unique critical envelope related to its PSD and R d , and a critical path with its inclination that depends on the hydro-mechanical conditions. The current results of internal erosion tests conducted by the authors plus those adopted from published literature are used to verify the proposed model.
Publisher: Springer Science and Business Media LLC
Date: 25-02-2021
Publisher: Canadian Science Publishing
Date: 12-2018
Abstract: This paper presents results from a series of piping tests carried out on a selected range of granular filters under static and cyclic loading conditions. The mechanical response of filters subjected to cyclic loading could be characterized in three distinct phases namely, (I) pre-shakedown, (II) post-shakedown, and (III) post-critical (i.e., the occurrence of internal erosion). All the permanent geomechanical changes such, as erosion, permeability variations, and axial strain developments, took place during phases I and III, while the specimen response remained purely elastic during phase II. The post-critical occurrence of erosion incurred significant settlement that may not be tolerable for high-speed railway substructures. The analysis revealed that a cyclic load would induce excess pore-water pressure, which, in corroboration with steady seepage forces and agitation due to dynamic loading, could then cause internal erosion of fines from the specimens. The resulting excess pore pressure is a direct function of the axial strain due to cyclic densification, as well as the loading frequency and reduction in permeability. A model based on strain energy is proposed to quantify the excess pore-water pressure, and subsequently validated using current and existing test results from published studies.
Publisher: Springer Science and Business Media LLC
Date: 05-01-2021
Publisher: Springer Science and Business Media LLC
Date: 02-08-2022
Publisher: Informa UK Limited
Date: 18-09-2022
Publisher: American Society of Civil Engineers
Date: 30-03-2017
Publisher: American Society of Civil Engineers (ASCE)
Date: 07-2019
Publisher: Springer Science and Business Media LLC
Date: 24-10-2019
Publisher: Springer Science and Business Media LLC
Date: 08-2020
Publisher: Research Square Platform LLC
Date: 12-2021
DOI: 10.21203/RS.3.RS-998184/V1
Abstract: This study presents a framework for semi-empirical slope stability analysis of Mohmand dam, an important ongoing mega concrete faced rockfill dam hydropower project in Pakistan. The project comprises of 213 m high hybrid dam that will produce 800 megawatt of clean hydropower energy in addition to an effective flood mitigation. Also, it will supply water for both irrigation and drinking to the provincial capital city, Peshawar. In this study, finite element and limit equilibrium methods have been used for slope stability analysis and factors of safety have been computed for all anticipated loading conditions including earthquake loading. The rockfill s les of main dam were obtained from the construction material site of Mohmand dam and the input parameters for slope stability analysis were obtained both empirically and through laboratory testing. Results of both limit equilibrium and finite element analyses have been compared and it was observed that the latter is more conservative than the former except for earthquake loading. The implications of current findings have been demonstrated using an important case study of an independent dam site that would boost the confidence of practitioners.
Publisher: ASTM International
Date: 11-12-2018
DOI: 10.1520/GTJ20170027
Publisher: Vilnius Gediminas Technical University
Date: 24-09-2016
Abstract: Internal erosion is a phenomenon whereby the filtrates under the influence of significant seepage forces accompany the finer fraction from potential internally unstable filters (e.g. broadly- and gap-graded soil), occasionally rendering them ineffective. The filter assessment for internal erosion or instability potential is emphasized through particle size distribution based geometrical criteria ignoring the effect of compaction. In this study, the results of hydraulic gradient controlled internal erosion tests conducted over a wide range of compacted sand-gravel mixtures were used to analyse some of the available geometrical criteria, which interestingly showed partial success in assessing the filter’s internal erosion potential. It was revealed that the occurrence of internal erosion is a combined function of particle size distribution and the relative density of soils that had been ignored in many of the existing criteria. A comparison between the assessments obtained from some of the particle size based criteria and that from a constriction size based technique was reported for a large body of published data. It was observed that the latter criterion, which incorporates the effects of both particle size distribution and relative density of soils in tandem, could assess the reported test results with higher accuracy.
Publisher: American Society of Civil Engineers (ASCE)
Date: 09-2016
Publisher: MDPI AG
Date: 19-07-2021
DOI: 10.3390/W13141976
Abstract: Results are reported from a series of filtration tests simulated using coupled computational fluid dynamics and the discrete element method (CCFD-DEM) to investigate the factors controlling the mechanism of base particle erosion and their subsequent capture in loaded granular filters. Apart from geometrical factors such as particle and void sizes, the filter effectiveness was found to be controlled by the magnitudes of the hydraulic gradients and the effective stresses. The results of numerical simulations revealed that the base soils exhibit significant stress reduction that reduces further due to seepage, and the base particles migrate into the filter, bearing very low effective stresses (i.e., localized piping in base soil). Based on the limit equilibrium of hydraulic and mechanical constraints, a linear hydromechanical model has been proposed that governs the migration and capture of base particles in the filter (i.e., filter effectiveness avoiding piping) for cases simulated in this study. Nevertheless, the proposed model agrees closely with the simulation results of this study and those adopted from other published works, thereby showing a reasonable possibility of using the proposed model as a measure of retention capacity of loaded protective filters.
Publisher: Springer Science and Business Media LLC
Date: 29-04-2019
Publisher: MDPI AG
Date: 28-08-2022
DOI: 10.3390/FRACTALFRACT6090474
Abstract: In this study, a rigorous mathematical approach used to compute an effective diameter based on particle size distribution (PSD) has been presented that can predict the hydraulic conductivity of granular soils with enhanced rigor. The PSD was discretized based on an abstract interval system of fractal entropy, while the effective diameter of soil was computed using the grading entropy theory. The comparisons between current entropy-based effective diameter (DE) and those computed using existing procedures show that the current DE can capture the particle size information of a given soil more accurately than others. Subsequently, the proposed DE was successfully implicated into Kozeny–Carman’s formula to deduce the saturated hydraulic conductivity of soils with enhanced accuracy. The proposed model was tested using current and previously published experimental data from literature. Not surprisingly, the results of the current model and those from previous experimental studies were found to be consistent, which can sufficiently verify the proposed entropy-based effective diameter model.
Publisher: Wiley
Date: 06-08-2018
Publisher: MDPI AG
Date: 26-05-2023
DOI: 10.3390/MA16114001
Abstract: The Helankou rock as the relics carrier in Ningxia, China, have been suffering from serious weathering caused by variable environmental conditions. To study the freeze-thaw damage characteristics of Helankou relics carrier rocks, three dry-wet conditions (i.e., drying, pH = 2 and pH = 7) together with freeze-thaw experiments have been carried out at 0, 10, 20, 30, and 40 cycles. Additionally, a series of triaxial compression tests have been carried out at four different cell pressures of 4 MPa, 8 MPa, 16 MPa, and 32 MPa in tandem with a non-destructive acoustic emission technique. Subsequently, the rock damage variables were identified based on elastic modulus and acoustic emission ringing counts. It has been revealed that the acoustic emission positioning points reflected that the cracks would be concentrated near the surface of main fracture at higher cell pressures. Notably, the rock s les at 0 freeze-thaw cycles failed in pure shear. However, both shear slip and extension along the tensile cracks were observed at 20 freeze-thaw cycles, while tensile-oblique shear failure occurred at 40 freeze-thaw cycles. Not surprisingly, the decreasing order of deterioration inside the rock was observed to be (drying group) (pH = 7 group) (pH = 2 group). The peak values of damage variables in these three groups were also found to be consistent with the deterioration trend observed under freeze-thaw cycles. Finally, the semi-empirical damage model could rigorously ascertain stress and deformation behavior of rock s les, thus providing theoretical basis to establish a protection framework for Helankou relics.
Publisher: ASTM International
Date: 07-09-2020
DOI: 10.1520/JTE20170321
Start Date: 2018
End Date: 2020
Funder: Science and Technology Department of Ningxia
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