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January 1996 - February 2015
Publications
Publications (363)
The static and dynamic stability of natural or constructed slopes can be affected by dissolution or dissolution-like phenomena. Their underlying mechanisms, however, remain unclear. New experimental results and discrete element simulations provide particle-level and macroscale information on the consequences of mineral dissolution on slope behavior...
Low-amplitude repetitive drained loading may hinder the long-term performance of engineered and natural systems. This study examines the volumetric and shear response of a uniform quarzitic sand subjected to repetitive drained simple shear loading under constant vertical stress while tracking the evolution of the secant stiffness and the small stra...
Near-surface seafloor properties affect offshore mining and infrastructure engineering. Shallow seafloor sediments experience extremely low effective stress, and consequently these sediments exhibit very low in-situ density, shear wave velocity and shear stiffness. We combined data extracted from the literature with new laboratory and field results...
Foam cement is an engineered lightweight material relevant to a broad range of engineering applications. This study explores the effects of aluminum chips on cement-bentonite slurry expansion, pressure development, and the evolution of pore topology. The terminal volume expansion under free-boundary conditions or the pressure build up under volume-...
The injection of CO2 into geological formations triggers inherently coupled thermo-hydro-chemo-mechanical processes. The reservoir pressure and temperature determine the CO2 density, the CO2-water interfacial tension, and the solubility of CO2 in water (hindered by salts and competing gases). The CO2-water interface experiences marked pinning onto...
In this article, we present a method used to model the initiation of bitumen-filled microfractures in immature, organic-rich source rocks. The first part presents the method used to calculate the stress distribution around the kerogen particles. The second part explains the method used to calculate the pressure change as a function of the transform...
Single and multi-phase fluids fill the pore space in sediments; phases may include gases (air, CH 4 , CO 2 , H 2 , and NH 3 ), liquids (aqueous solutions or organic compounds), and even ice and hydrates. Fluids can experience instabilities within the pore space or trigger instabilities in the granular skeleton. Then, we divided fluid-driven instabi...
Evaporite deposition and seafloor spreading are two salient geological processes in the geological history of the Red Sea. We piece together the available evidence about rift evolution and evaporite formation to constrain the deposition history, analyze creep, and advance a plausible explanation for the preservation of these soluble formations. At...
The geomechanical behavior of methane hydrate bearing sediments (MHBS) is influenced by many factors, including temperature, fluid pressure, hydrate saturation, stress level, and strain rate. The paper presents a visco-elastoplastic constitutive model for MHBS based on an elastoplastic model that incorporates the effect of hydrate saturation, stres...
Conventional particulate additives fail to control drilling fluid losses into large-aperture fractures. The separate injections of a bentonite-cement-oil suspension and water can cause rapid hydration, swelling and hardening to effectively plug fractures. This experimental study investigates underlying processes and implications in view of optimal...
Sediment accumulations within the Red Sea central deeps have unique genesis and properties. We piece together available information to understand their geological setting and formation history, and conduct an extensive sediment characterization study to assess their geotechnical properties in order to anticipate engineering/mining implications. The...
The initiation of bitumen-filled microfractures was analysed in the organic-rich Maastrichtian carbonate mudrocks of Jordan, which show great potential as source rocks and for a future unconventional hydrocarbon play. A modelling approach was performed to assess the possible scenarios causing horizontal small-scale (mm to cm in length) bitumen frac...
Rock mechanical properties such as strength, hardness, brittleness, and elastic moduli of layered rocks are essential in guaranteeing wellbore integrity and predicting natural fracture occurrence for successfully managing reservoir development. These parameters are also critical for developing low permeability, unconventional reservoirs for which i...
Fractures provide preferential flow paths and establish the internal “plumbing” of the rock mass. Fracture surface roughness and the matedness between surfaces combine to delineate the fracture geometric aperture. New and published measurements show the inherent relation between roughness wavelength and amplitude. In fact, data cluster along a powe...
Electromagnetic phenomena support the development of exceptional methods for non-destructive, non-contact geomaterial characterization and subsurface process monitoring. Such phenomena include Ohmic conduction, electromagnetic wave propagation and nuclear magnetic resonance. The physical parameters involved include DC conductivity σ, complex permit...
Fractures prevail mechanical behavior of a rock mass and confer an overall anisotropic response. Engineering analyses in the elastic regime often use transverse isotropy to model fractured rock masses with a single fracture set. An alternative implicit joint-continuum model combines the mechanical response of the intact rock and fractures by adding...
Employing network science to understand particle interactions helps manufacture advanced materials with superior force transmission and heat transfer. However, knowledge of the dependence of networks on particle features such as shape is missing. This study computes particle shape ─ the average of three-dimensional sphericity and roundness, and mul...
Soft viscoelastic biological products such as biopolymers and biofilms have recently garnered significant interest as alternative biogrout materials for ground improvement because of their nontoxic and biodegradable characteristics. However, the impact of soft gel-like viscoelastic pore fillers on the undrained response of treated soils remains poo...
Accurate stress-strain measurements in triaxial tests are critical to compute reliable mechanical parameters. We focus on compliance at the interfaces between the specimen and endcaps, and test specimens under various triaxial conditions using different instrumentation protocols. The tested materials include aluminum, Eagle Ford shale, Berea sandst...
Self-assembly is ubiquitous at all scales in nature. Most studies have focused on the self-assembly of micron-scale and nano-scale components. In this study, we explore the self-assembly of millimeter-scale magnetic particles in a bubble-column reactor to form 9 different structures. Two component systems (N-N and S-S particles) assemble faster tha...
A broad diversity of biological organisms and systems interact with soil in ways that facilitate their growth and survival. These interactions are made possible by strategies that enable organisms to accomplish functions that can be analogous to those required in geotechnical engineering systems. Examples include anchorage in soft and weak ground,...
Granular flow is common across different fields from energy resource recovery and mineral processing to grain transport and traffic flow. Migrating particles may jam and form arches that span constrictions and hinder particle flow. Most studies have investigated the migration and clogging of spherical particles, however, natural particles are rarel...
Sediments experience shear and volumetric strains during freeze-thaw cycles. Measurements during globally drained and undrained cycles under constant deviatoric stresses show that the asymptotic shear and volumetric response varies with sediment type and drainage conditions. In particular, the sediment response is intimately related to the ice pore...
Accurate stress-strain measurements in triaxial tests are critical to compute reliable mechanical parameters. We focus on compliance at the interfaces between the specimen and endcaps, and test specimens under various triaxial conditions using different instrumentation protocols. The tested materials include aluminum, Eagle Ford shale, Berea sandst...
Offshore geo-engineering requires reliable sediment parameters for analysis and design. This study proposes a robust framework for effective stress-dependent geotechnical and geoacoustic properties for seabed analyses based on geophysical models, new experimental data and extensive datasets compiled from published studies that cover a wide range of...
The geo-science and engineering fields have critical roles to play towards a sustainable energy future. This state-of-the-art review focusses on five areas where the geotechnical community has been involved the most: the oil and gas sector with emphasis on methane hydrates, carbon geological storage, geothermal, energy geo-storage, and nuclear wast...
Cell counts decrease with sediment depth. Typical explanations consider limiting factors such as water availability and chemistry, carbon source, nutrients, energy and temperature, and overlook the role of pore size. Our analyses consider sediment self-compaction, the evolution of pore size with depth, and the probability of pores larger than the m...
Hydrate-bearing sediments are a potential source of energy. Depressurization is the preferred production method in mechanically stable and highly permeable sandy reservoirs. The goal of this study is to develop closed-form analytical solutions for multi-well depressurization strategies and to explore the synergistic interactions among wells. The ke...
The mechanisms leading to the electrification of water when it comes in contact with hydrophobic surfaces remains a research frontier in chemical science. A clear understanding of these mechanisms could, for instance, aid the rational design of triboelectric generators and micro- and nano-fluidic devices. Here, we investigate the origins of the exc...
Heat flow controls the design and operation of a wide range of engineered geosystems. This study uses transient thermal probe measurements to determine the evolution of the thermal conductivity of air-dry and water-saturated sand-silt mixtures as a function of effective stress. Results confirm that the thermal conductivity of soils varies with stat...
We are grateful to the discussers for their comments. Without hesitation, contributions by Indian colleagues have played a critical role in today’s understanding of fly ash properties and behavior. In fact, 14 references in the original paper recognize their work, including contributions by the discussers [data compilations referenced in our paper...
Hypothesis. Particle accumulation at liquid-liquid or liquid-gas interfaces can significantly alter capillary behavior and give rise to unusual interfacial phenomena including the asymmetric macroscopic mechanical response of the interface.
Experiments. This study explores the accumulation of cetyltrimethylammonium bromide-modified nanoparticles...
Modeling of the phase transitions anticipated in gas hydrate bearing sediments (GHBS) is critical for a proper understanding of time-dependent changes in states and volumes (e.g. the production of methane from this type of soils). We propose a new pseudo-kinetic approach to simulate the typical phase changes anticipated in GHBS, using published exp...
Soils often experience repetitive changes in pore water pressure. This study explores the volumetric and shear response of contractive and dilative sand specimens subjected to repetitive changes in pore water pressure, under constant deviatoric stress in a triaxial cell. The evolution towards a terminal void ratio eT characterizes the volumetric re...
Hydrate-bearing sediments are relevant to the organic carbon cycle, seafloor instability, and as a potential energy resource. Sediment characteristics affect hydrate formation, gas migration and recovery strategies. We combine the physics of granular materials with robust compaction models to estimate effective stress and capillary pressure in orde...
The probability of failure of tailings dams and associated risks demand improvements in engineering practice. The critical state line provides a robust framework for the characterization of mine tailings. New experimental data for non-plastic platinum tailings and a large database for tailings and non-plastic soils (grain size between 2 μm and 500...
Multiphysics low-perturbation methods provide
complementary information needed for comprehensive
sediment characterization and process monitoring. We
describe underlying physical concepts and report new results
gathered using nuclear magnetic resonance, thermal
conduction, electromagnetic and elastic waves.
Multiphysics low-perturbation methods provide
complementary information needed for comprehensive
sediment characterization and process monitoring. We
describe underlying physical concepts and report new results
gathered using nuclear magnetic resonance, thermal
conduction, electromagnetic and elastic waves.
Pressure solution-precipitation is a diagenetic process often involved in compaction, hardening, creep and healing. This study explores the evolution of pressure-dependent mineral dissolution using the discrete element method where grains are gradually contracted in proportion to the total normal force they carry. Under zero lateral strain and cons...
The migration and retention of fine particles in porous media are important phenomena in natural processes and engineering applications. Migrating particles experience physicochemical interactions with carrier fluids, pore walls and other migrating particles. The governing dimensionless ratios capture particle-level forces, flow conditions, and geo...
The physical properties of natural gas hydrate-bearing sediments are critical for the analysis of natural systems and for the design of gas production strategies. This work explores the properties of fine-grained sediments containing segregated hydrate lenses. Our analyses show that hydrate formation is grain-displacive when the product of the effe...
Accurate stress-strain measurements in triaxial compression tests are critical to derive correct values of stiffness, Poisson's ratio, and the Biot α-parameter. Yet, inherent biases can produce unrepresentative rock properties. This study investigates the impact of different measurements using strain gauges and LVDTs. A detailed analysis reveals th...
Haines instabilities are sudden jumps of the fluid interface accompanied by fluid redistribution and a transient pressure response. Haines jumps affect global displacement patterns in porous media, promote fingered invasion, increase fluid trapping, and contribute to hysteretic saturation. Detailed analyses and experimental results show that jumps...
Mineral dissolution and subsurface volume contraction can result from various natural and engineered subsurface processes. This study explores localized granular dissolution in sediments under constant vertical stress and zero lateral boundaries using 2D and 3D discrete element simulations to gather macro-scale and particle-scale information during...
Fractures control the hydro-mechanical behavior of rock masses. Explicit numerical analyses require detailed information on fracture properties, spacing, and orientation. This paper advances an implicit joint-continuum model for the coupled hydro-mechanical analysis of regularly spaced-persistent fractured rock masses. The stiffness tensor combines...
A single planar fracture geometry dominates the process of hydraulic fracturing in homogeneous, isotropic and cohesive materials. However, this fracture geometry cannot explain the high recovery efficiency observed in shale gas and enhanced geothermal energy. Experimental and numerical studies reported here demonstrate that pre-fractured, structure...
![Fig. 10 Shear S-wave velocity. Details in [9, 47]](profile/Farizal-Hakiki/publication/333345418/figure/fig3/AS:764070936465410@1559180115151/Shear-S-wave-velocity-Details-in-9-47_Q320.jpg)
Research and engineering projects during the last century have advanced the understanding of soil behavior and contributed extensive datasets. Nevertheless, the granular nature of soils challenges the accurate prediction of soil properties. In this context, a physics-inspired and data-driven approach helps us anticipate the soil response. The granu...
Geotechnical structures often experience a large number of repetitive loading cycles. This research examines the quasi-static mechanical response of sands subjected to repetitive loads under zero lateral strain boundary conditions. The experimental study uses an automatic repetitive loading frame operated with pneumatic pistons. Both vertical defor...
Knowledge gaps and management shortcomings contribute to catastrophic dam failures
The adsorption of nanoparticles onto mineral surfaces is a major limitation for applications that require long transport distances, such as enhanced oil recovery. This study investigates silica nanoparticle transport and adsorption in long granular columns, with emphasis on the adsorption onto carbonate substrates, given the fact that carbonate res...
Gas migration mechanisms control the release of gas from seafloor sediments. We study underlying phenomena using transparent sediments subjected to controlled effective stress; this experimental approach allows high-resolution real-time monitoring of gas migration through cohesionless granular materials under 3-D boundary conditions. Observed migra...
Desiccation cracks affect all mechanical and conduction properties. Previous studies have investigated the formation of surface desiccation cracks in fine-grained sediments in relation to their compressibility and suction potential. This study explores the formation of internal desiccation cracks in saturated kaolinite specimens consolidated inside...
9 10 Characterization studies conducted on Class-F fly ash specimens gathered from different producers in the 11 southeastern USA confirm general trends reported for fly ash worldwide. Additional tests and detailed 12 analyses explain the spread in specific gravity (inter-particle porosity cenospheres), highlight the tendency 13 to segregation and...
Characterization studies conducted on Class-F fly-ash specimens gathered from different producers in the southeastern United States confirm general trends reported for fly ash worldwide. Additional tests and detailed analyses explain the spread in specific gravity (interparticle porosity cenospheres), highlight the tendency to segregation and layer...
Science of Carbon Storage in Deep Saline Formations: Process Coupling across Time and Spatial Scales summarizes state-of-the-art research, emphasizing how the coupling of physical and chemical processes as subsurface systems re-equilibrate during and after the injection of CO2. In addition, it addresses, in an easy-to-follow way, the lack of knowle...
Ultra-sensitive solid-state magnetic sensors are in strong demand in many applications where currently available sensors are inadequate. We have used high performance magnetic tunneling junction (MTJ) sensors and pushed the magnetic sensing limit to a high level. We have incorporated double-staged magnetic flux concentrators, one on the MTJ chip lev...
Capillarity traps fluids in porous media during immiscible fluid displacement. Most field situations involve relatively long time scales, such as hydrocarbon migration into reservoirs, resource recovery, nonaqueous phase liquid remediation, geological CO2 storage, and sediment-atmosphere interactions. Yet laboratory studies and numerical simulation...
Author's copy of chapter 17.
Granular materials must be engineered for use in emerging geo-energy infrastructures, where enhanced or suppressed heat transfer is required. The thermal conductivity of dry granular materials is controlled by the number of inter-particle contacts and their quality. Therefore, their thermal conductivity depends on fabric (grain size distribution as...
Methane hydrates are ice-like compounds made of gas methane and water. Hydrates are stable under low-temperature and high-pressure conditions constraining their occurrence in sediments to marine and permafrost settings. A shift from the stability condition triggers an endothermic hydrate dissociation with the associated release of gas and water, im...
Migratory particles in porous media experience mechanical and chemo-physical interactions with fluids, pore walls and other particles. The resulting forces (buoyant weight, drag, inertia, and electrical particle-particle and particle-wall) determine particle migration, adhesion and pore clogging. We investigate underlying pore-scale phenomena in co...
The study of fractured rock masses in the laboratory remains challenging because of the large specimen sizes and bulky loading systems that are required. This article presents the design, structural analysis, and operation of a compact and self-reacting true triaxial device for fractured rock. The frame subjects a 50 cm by 50 cm by 50 cm fractured...
This paper shows the effect of anisotropic stress state on intermediate strain properties of cylindrical samples containing spherical glass particles. Tests were carried out with the modified resonant column device available at Ruhr-Universität Bochum. Dry samples were subjected to two anisotropic stress States: (a) cell pressure, σh′ , constant an...
This article presents an analysis of previously published hydraulic conductivity data for a wide range of sediments.All soils exhibit a prevalent power trend between the hydraulic conductivity and void ratio. Data trends span 12 orders of magnitude in hydraulic conductivity and collapse onto a single narrow trend when the hydraulic conductivity dat...
Oil and gas account for 60% of the world's energy consumption. Drilling muds that are used to advance oil and gas wells must be engineered to avoid wellbore integrity problems associated with mud cake formation, to favor cake erosion during cementing, and to prevent partial differential sticking. We developed a robust mud cake growth model for wate...
Small pores in high specific surface clay-rich caprocks give rise to high capillary entry pressures and high viscous drag that hinder the migration of buoyant carbon dioxide CO2. We measured the breakthrough pressure and ensuing CO2 permeability through sediment plugs prepared with sand, silt, kaolinite and smectite, and monitored their volumetric...
The estimation of gas production rates from hydrate bearing sediments requires complex numerical simulations. This manuscript presents a set of simple and robust analytical solutions to estimate the maximum depressurization-driven recoverable gas. These limiting-equilibrium solutions are established when the dissociation front reaches steady state...
Recent macro- and particle-scale advances in unsaturated soil behaviour have led to an enhanced understanding of the effects of moisture changes on soil response. This research examines desiccation cracks as a suction–contraction-coupled process using sand–clay mixtures. Suction–moisture measurements highlight the role of fines on suction potential...
Grain-scale characteristics and formation history determine spatial variability in granular masses. We investigate the effect of spatially varying stiffness on the load-deformation response under zero-lateral strain conditions using numerical simulations of correlated random fields, where the granular medium is represented by a non-linear stress-de...
Depressurization gives rise to complex sediment–well interactions that may cause the failure of wells. The situation is aggravated when high depressurization is imposed on sediments subjected to an initially low effective stress, such as in gas production from hydrate accumulations in marine sediments. Sediment–well interaction is examined using a...