Engineering Commons^™

A Study About The Influence Of Joint Roughness On The Volume Of Rock Blocks, Tie-Xin Liu, Jia-Qi Li, Jian-Hui Deng, Zheng-Hu Zhang, Jun Zheng

Rock and Soil Mechanics

The structure of a rock mass directly controls its mechanical and hydraulic properties, and the distribution of rock block volumes can directly reflect the structural characteristics of the rock mass. Currently, many studies simplify the joint surfaces as planes and ignore the influence of roughness on the volume of rock blocks. In this study, the Hurst exponent (H) and root-mean-square height (Rq) were used to characterize joint roughness, and the influence of joint roughness on the quantity and volume distribution of rock blocks was investigated. The results show that: (1) H and Rq control the roughness of the joint, and …

A Calculation Method For Deformation Of Diaphragm Wall Of Narrow Deep Foundation Pit In Soft Soil Considering Spatio-Temporal Effect, Kun-Yong Zhang, Meng Zhang, Bin Sun, Fu-Dong Li, Yong-Zhou Jian

Rock and Soil Mechanics

To accurately evaluate the safety of foundation pit construction in soft soil area and its impact on the surroundings, the time and space influencing factors during excavation cannot be ignored. In this paper, based on the excavation of a deep foundation pit in the soft soil area of the Yangtze River floodplain, a 3D finite element model was established considering the combination of bottom-up and top-down constructions, and the calculated values of horizontal displacement of the diaphragm wall were compared with the measured values to verify the reliability of the finite element calculation. Based on theoretical analysis, numerical calculation and …

Reliability Analysis Of Rock Tunnel Stability Based On Interval Non-Probability Under Multiple Failure Modes, Xiang Li, Jing-Tong Wang, Heng Wei

Rock and Soil Mechanics

For the reliability analysis of rock tunnel stability, considering the difficulty in obtaining the statistical data on rock mass parameters, there is the potential inadequacy when using the probabilistic reliability method; on the other hand, the rock tunnel stability is intimately pertinent to a variety of failure modes, meaning it is necessary to consider the issue on structural system reliability. First, based on the interval theory, the uncertainty parameters were represented by adopting the interval variables. Subsequently, aiming at the coexistence of multiple failure modes in rock tunnel engineering, the concept of structural system reliability was introduced, and then a …

Experimental Study On Sand Anti-Seepage By Microorganism–Bentonite Combined Mineralization, Yu Zhang, Xiang He

Rock and Soil Mechanics

The seepage of sandy foundation would lead to the collapse of foundation and the destruction of engineering structure. A series of large-scale sand column seepage model experiments was carried out by using microorganism–bentonite combined mineralization method. The in-depth discussion was conducted for the effects of sand particle size, slurry liquid-to-solid ratio and treatment cycles on the permeability, internal erosion characteristic and bentonite and calcium carbonate precipitate distribution of sand. Moreover, the stability of sealing and the microstructure were thoroughly investigated, and the treatment effect of microorganism–bentonite combined mineralization method was evaluated. It was found that this method could improve the …

Optimal Strut Position Of Deep Foundation Pit With Convex Corner Under Surcharge Of Adjacent Building, Bao-Guo Chen, Zeng-Pan Jia

Rock and Soil Mechanics

Since the mechanical behavior of the convex corner is complex due to surcharge near the excavation, it is of great importance to evaluate the influence of changes in strut position on the convex corner. Field monitoring and numerical simulations were used to analyze the influence law of the changes of strut position on the deformation and stress characteristics of the convex corner area. The axial force of inner strut, the lateral earth pressure on the pile, the horizontal displacement of the pile, the settlement of adjacent building and the bending moment of the pile were obtained. The research results show …

3d Experimental Studies Of Temperature And Crystallographic Effects On Creep And Strength In Rock Salt, Amirsalar Moslehy

Doctoral Dissertations

Salt domes utilization as storage reservoirs in the energy sector has led to extensive studies on rock salt’s mechanical and geothermal behavior. These important facilities’ safety and serviceability rely on understanding rock salt’s compressive strength and creep behavior under various loading directions, water contents, in-situ stresses, and temperatures. Despite numerous studies on rock salt’s mechanical behavior in the literature, there are still many unanswered questions about rock salt’s behavior. This dissertation was aimed at utilizing state-of-the-art experimental techniques such as 3D synchrotron micro-computed tomography (SMT) and 3D x-ray diffraction (3DXRD) along with hundreds of compression and creep experiments to enhance …

Initiation Criteria For The Onset Of Geomagnetic Substorms Based On Auroral Observations And Electrojet Current Signatures, Mayowa Michael Kayode-Adeoye

<strong> Theses and Dissertations </strong>

In recent years, several substorm onset criteria have been developed, either from auroral observations (many authors) or from auroral electrojet properties such as those described by (Forsyth et al., 2015; Maimaiti et al., 2019; Newell & Gjerloev, 2011; Partamies et al., 2011) The different criteria are being investigated using a low order physics model of the magnetosphere called WINDMI (Spencer et al., 2009) and inferences are being made in line with the WINDMI model. The model variables will be compared with the criteria for substorm onset proposed by examining the SML index.

The WINDMI model uses solar wind and IMF …

Gravel Conveyance System: An Evaluation On E. Coli Removal Capabilities, Madison Grace

<strong> Theses and Dissertations </strong>

In many rural, low-income communities such as the Black Belt of Alabama, there is a lack of wastewater infrastructure and solutions leaving homeowners non-compliant to state and federal law and with potential health risks on their property. New regulations have allowed for onsite, surface discharge for single family homes that are not connected to a centralized sewer or large flow development. These new regulations also contain strict disinfection criteria for the treated wastewater that will be discharged. A low-cost and low-maintenance treatment system that provides adequate disinfection is necessary to allow homeowners to take advantage of the new opportunity for …

Co2 Storage Capacity And Injectivity Of Stacked Carbonates Of The Pennsylvanian And Permian In Western Nebraska, Lateef Lawal

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Geological carbon storage (GCS) is a critical aspect of carbon capture and storage (CCS) in which captured CO₂ from power plants and industrial processes is injected and stored securely underground. Potential subsurface rock formations include saline aquifers, depleted oil and gas reservoirs, unmineable coal seams and volcanic rocks. GCS technology has been proven in the United States and many other parts of the world as a net-zero carbon emission strategy to mitigate the current climate crisis of our planet. Unlike other states such as Wyoming, GCS projects are still in the early phases in Nebraska. The goal of this …

Residual Trapping Of Co2, N2, And A Co2-N2 Mixture In Indiana Limestone Using Robust Nmr Coreflooding: Implications For Co2 Geological Storage, Amer Alanazi, Auby Baban, Muhammad Ali, Alireza Keshavarz, Stefan Iglauer, Hussein Hoteit

Research outputs 2022 to 2026

Carbon capture and sequestration (CCS) in geological formations is a prominent solution for reducing anthropogenic carbon emissions and mitigating climate change. The capillary trapping of CO2 is a primary trapping mechanism governed by the pressure difference between the wetting and nonwetting phases in a porous rock, making the latter a key input parameter for dynamic simulation models. During the CCS operational process, however, the CO2 is prone to contamination by impurities from various sources such as surfaces (e.g., pipelines and tanks) and the subsurface (e.g., existing natural gas). Such contamination can strongly influence the overall CO2 wettability, storage capacity, and …

A New Approach To Predicting Vertical Permeability For Carbonate Rocks In The Southern Mesopotamian Basin, Emad A. Al-Khdheeawi, Raed H. Allawi, Wisam I. Al-Rubaye, Stefan Iglauer

Research outputs 2022 to 2026

Reservoir performance depends on many factors, and the most important one is permeability anisotropy. In addition, with high heterogeneity, it is essential to find unique relationships to predict permeability. Therefore, this study aims to predict vertical permeability based on horizontal permeability and porosity and to find new equations for carbonate reservoirs. This work relied on the 398 measured points of cores data collected from several wells in carbonate reservoirs. A new correlation for predicting vertical permeability for the whole data (369 samples) as a function of horizontal permeability and porosity has been developed. The results indicate that this new correlation …

Effect Of Methylene Blue On Wetting Characteristics Of Quartz/H2/Brine Systems: Implication For Hydrogen Geological Storage, Fatemah Alhamad, Mujahid Ali, Nurudeen P. Yekeen, Muhammad Ali, Hussein Hoteit, Stefan Iglauer, Alireza Keshavarz

Research outputs 2022 to 2026

Hydrogen (H2) is considered a promising replacement for fossil fuels due to its enormous potential as an environmentally friendly and sustainable option compared to carbon-based fossil fuels. However, storing the vast quantity of H2 required to satisfy the global energy demand on the earth's surface can be difficult due to its compressibility and volatility. The best option for large-scale storage is underground H2 storage (UHS), which can be retrieved when needed. Rock wettability is vital in UHS because it determines the H2 storage capacity, containment security, and potential withdrawal and injection rates. Organic acid inherent in storage formations could make …

Compound Flooding In A Non-Stationary World: A Primer For Practice, Gerarda M. Shields, J. Rolf Olsen, Miguel Medina Jr., Jayantha Obeysekera, Poulomi Ganguli, Carlo Demichele, Gianfausto Salvadori, Mohammad Reza Najafi, Hamed Moftakhari, Ferdinand Diermanse, Amir Aghakouchak

Publications and Research

Compound flooding conditions present a significant challenge for civil engineers in their pursuit to design for and maintain the integrity of a structure’s entire life cycle. Coupled with non-stationary processes due to a changing climate and land use change, risk is a moving target. Through the support of ASCE’s Task Committee on Compound Flooding, the Hydroclimatology Engineering Adaptation (HYDEA) sub-committee is developing a Manual of Practice (MOP) to provide a synthesis of available tools and methods of best practice for civil engineers designing for compound flooding conditions. This paper presents a primer for practicing civil engineers on this work. Hydrodynamic …

Investigation Of The Fracture Process Zone And Behavior Of The Macro-Scale Fatigue Cracks In Brittle Rock Specimens, Nazife Erarslan

Rock and Soil Mechanics

The importance of this study is to explain the fatigue damage mechanism while addressing the effect of fatigue on the fracture toughness (KIC) using the brittle Brazilian specimens and to show for the first time in the literature the behavior of macroscale cracks that open and close in brittle rock without leading to eventual failure. The KIC was reduced by 35% due to the cyclic loading, and the reduction of the indirect Brazilian strength was found to be reduced by 30%. The fatigue cracks were observed to open and close elastically without failure and have been recorded by a camera …

Mode I Crack Morphology And Fracture Surface Roughness Of Granite Under Impact, Xue-Song Wang, Lian-Jun Guo, Xin Liu, Ding Deng, Jiu-Yang Zhang, Zhen-Yang Xu

Rock and Soil Mechanics

To study the response of mode I cracks under impact loading, the dynamic fracture test on the single cleavage triangle (SCT) granite specimens with the lateral opening was carried out using a split Hopkinson pressure bar test system. The Hough transform method was used to quantitatively describe the distributions of the surface crack lengths and angles, and the relationship between them and the absorbed energy of the specimen was analyzed. The three-dimensional (3D) point cloud data of the fracture surface was obtained by using a 3D surface topography detection device, and a fracture surface reconstruction method based on the threshold …

Upper Bound Analysis Of Uplift Piles In Saturated Clay And Soil Plug Effect, Ke-Wen Zhu, Jian Yu, Mao-Song Huang

Rock and Soil Mechanics

A new mechanism is established and applied to the upper bound analysis of uplift piles in saturated clay. Upper bound solutions of uplift capacities of closed and open-ended piles are analyzed. The new mechanism is verified by comparing with elastoplastic finiteelement, existing lower bound and API solutions. Its reliability is assessed through case studies including one centrifuge test and two field tests. The effects of the pile length-diameter ratio, pile surface roughness, non uniformity of undrained soil strength and length of soil plug on the uplift bearing capacity are considered. A formulation predicting the net bearing capacity of closed-ended uplift …

Shear Strength Characteristics Of Unsaturated Rubber Silt Mixtures, En-Quan Zhou, Yuan Yao, Lei Cui, Long Wang

Rock and Soil Mechanics

To study the shear strength characteristics of unsaturated rubber silt mixtures, a series of direct shear tests was conducted on the rubber silt mixtures with different rubber particle contents and water contents. Based on the particle contact state theory, the meso contact mode of rubber silt mixtures was constructed, and the calculation method of rubber silt mixtures skeleton void ratio based on different rubber content was obtained. The test results show that the shear strength of rubber silt mixtures decreases with the increase of skeleton void ratio at a low water content, while the strength of rubber silt mixtures increases …

A Simplified Algorithm For Predicting Creep Settlement Of High Fill Based On Modified Power Law Model, Jian Huang, Pu-Rong De, Yang-Ping Yao, Ren Peng, Ji-Lin Qi

Rock and Soil Mechanics

The creep settlement dominates the long-term deformation of high fill foundation after construction and cannot be ignored. The reliable prediction of creep settlement provides an important guideline for judging whether settlement is stable and arranging subsequent construction. The modification of the traditional power law model for predicting the one-dimensional creep deformation of soil is proposed, which can describe the one dimensional creep deformation of clay, sand and soil-rock mixture. The modified model satisfies the requirement that the growth of the creep deformation has an asymptote with respect to time; that is to say, the creep deformation grows continually and approaches …

Probabilistic Evaluation Of Excavation Unloading Response Of Rock Slope Considering The Uncertainty Of Mechanical Parameters, Guo-Feng Liu, Kun Feng, Chang-Gen Yan, Guang-Liang Feng, Ding-Ping Xu, Chi Zhou

Rock and Soil Mechanics

There are many studies on the spatial variability of mechanical parameters of jointed rock masses and the reliability of slopes with potential slip surface, but the research on the spatial variability of mechanical parameters of rock slopes and the uncertainty analysis of excavation unloading response (deformation and plastic zone) is limited. A probabilistic evaluation method for excavation unloading response of rock slopes considering the uncertainty of mechanical parameters is proposed. Based on laboratory rock mechanical tests and geological survey mapping data, the probabilistic statistical models of rock mass mechanical parameters of slopes are constructed by using Hoek-Brown empirical criterion and …

Long-Term Stress Characteristics And Load Reduction Effect Of High-Fill Box Culverts With Eps Slabs, Qi Gao, Bao-Guo Chen, Sen Wu, Shan Yuan, Meng-Yao Sun

Rock and Soil Mechanics

Laying expandable polystyrene (EPS) slabs on the top of high-fill box culverts to reduce earth pressure has been used in engineering practice, but the creep of EPS slabs will cause the earth pressure on the box culvert to change over time. The present design theory of box culverts cannot clearly reflect the long-term load reduction effect of EPS slabs and the long-term stress characteristics of box culverts. In this analysis, model tests were carried out to investigate the short-term stress characteristics of the box culvert with EPS slabs, and a numerical model was validated by the model test results. Then …

Simulation Of Seepage And Heat Transfer In 3d Fractured Rock Mass Based On Fracture Continuum Method, Dong-Dong Liu, Li-Xin Wei, Guo-Yuan Xu, Yan-Yong Xiang

Rock and Soil Mechanics

The main challenge of simulating the processes of seepage and heat transfer in fractured rock mass is the heterogeneity of rock mass at various scales. In order to balance the efficiency and accuracy of numerical simulation, the two-dimensional fracture continuum method is extended to a three-dimensional one. Based on the depth-first search algorithm, the effective fractures contributing to the permeability of rock blocks are collected. The block permeability tensor is obtained by considering the contribution of effective fractures and rock matrix. The finite element software COMSOL Multiphysics is integrated with Matlab to generate a three-dimensional fracture continuum model that contains …

Mechanism Of Liquefaction-Induced Lateral Spreading In Liquefiable Inclined Sites, Ke-Min Jia, Cheng-Shun Xu, Xiu-Li Du, Xiao-Ling Zhang, Jia Song, Zhuo-Lin Su

Rock and Soil Mechanics

A numerical model of the liquefaction horizontal free-field shaking table test was developed based on the completed large-scale shaking table test of liquefaction horizontal free field using the OpenSees finite element platform, and the numerical model was verified. Based on this, a free-field numerical model of the overall inclined foundation was established, and the non-cyclic dynamic response of the liquefaction lateral spreading site and the mechanism of liquefaction-induced lateral spreading were discussed. The results show that the established numerical model can effectively simulate the seismic response in liquefiable sites. There was significant relative displacement at the interface between liquefiable loose …

Roughness Characterization Of Rock Fracture And Its Influence On Fracture Seepage Characteristics, Lei Gan, Yu Liu, Zong-Liang Zhang, Zhen-Zhong Shen, Hong-Ying Ma

Rock and Soil Mechanics

Roughness of rock fracture has a significant influence on the seepage characteristics of fracture. The point cloud data of rock fracture surface was collected by three-dimensional (3D) optical scanning system. The joint roughness coefficient (JRC) and surface roughness ratio (Rs) were calculated by SURFER and GEOMAGIC STUDIO, and the quantitative relationship between JRC and Rs was established. The effects of JRC and Rs on the fracture seepage characteristics in limestone were investigated by conducting seepage tests under the coupling effect of stress, seepage and chemical interaction. The results show that JRC is a logarithmic function of Rs, with the R-squared …

Strength Deterioration Characteristics Of Lime-Metakaolin Improved Earthen Site Soil Under Freeze-Thaw Cycles, Xin-Ming Li, Hao-Yang Zhang, Di Wu, Yan-Rui Guo, Ke-Bin Ren, Yun-Zhi Tan

Rock and Soil Mechanics

The Central Plains are located in an area that experiences seasonal freeze-thaw cycles, which can have significant effects on the soil structure of soil relics. To determine if lime-metakaolin (L-MK) is a feasible alternative to natural hydraulic lime (NHL) for earth site restoration work, tests were conducted using lime, metakaolin and silty sand from the site as main raw materials. Mass loss, unconfined compressive strength and splitting tensile strength tests were carried out on L-MK improved silty sand soil undergoing different numbers of freeze-thaw cycles to study its strength characteristics in depth. X-ray diffraction (XRD) thermogravimetry (TG), and scanning electron …

Improvement Of Rainfall Boundary Treatment Based On The Diffusion Wave Approximation Equation, Xu Wang, Mei Dong, Meng-Yue Kong, Yun-Peng Deng, Ri-Qing Xu, Xiao-Nan Gong

Rock and Soil Mechanics

During the simulation of rainwater infiltration, the conventional rainfall boundary cannot accurately reflect the influence of the variation of ponding water depth on the calculation of actual rainwater infiltration rate. To address this issue, the conventional rainfall boundary is improved by incorporating the diffusion wave approximation equation, allowing for the coupling of ponding water depth variations with actual infiltration rate during heavy rainfall events. Additionally, the accuracy of the improved boundary is validated through two classical experimental cases. The improved boundary is subsequently applied to the simulation of an actual engineering scenario. The findings indicate that the improved rainfall boundary …

Three-Dimensional Unified Mechanical Model And Calculation Method Of Uplift Capacity Of Horizontal Rectangular Anchor Plate In The Whole Region In Sand, Wei Hu, Hui Wang, Chen Yao, Dong-Xue Hao, Dan-Da Shi

Rock and Soil Mechanics

Uplift of the horizontal rectangular anchor plate is a typical three-dimensional problem. However, it is difficult to characterize the sliding surface of soil around the anchor plate in the limit state for its shape is affected by a combination of the length-width ratio and embedment ratio of the anchor plate. Combining the results of ABAQUS 3D numerical simulation and 2D sliding surface analysis, it is found that the geometric form of the 3D sliding surface in any horizontal section within its buried depth range can be described by a closed graph, including four segments of straight lines parallel and equal …

Refined Analysis On Stress State Of Cutoff Wall Of High Asphaltic Core Dam On Super-Deep Overburden, De-Gao Zou, Yong-Qian Qu, Xian-Jing Kong, Kai Chen, Jing-Mao Liu, Jin Gong

Rock and Soil Mechanics

The concrete cutoff wall is the main anti-seepage structure of the rockfill dam resting on the deep overburden foundation, and is the key to ensuring the dam safety. Therefore, it is of great significance to accurately simulate the stress state of cutoff wall for evaluation of the rockfill dam resting on the deep overburden. Combining the incremental iteration method and the finite element-scaled boundary finite element coupling method (FEM-SBFEM), this paper realizes the trans-scale refined numerical analysis of the stress and deformation of the rockfill dam, which overcomes the low precision of the conventional midpoint increment method in solving local …

Characteristics Of The Cumulative Plastic Deformation And Pore Water Pressure Of Saturated Sand Under Cyclic Intermittent Loading, Qi Yang, Xiao-Ya Wang, Ru-Song Nie, Chen Chen, Yuan-Zheng Chen, Fang Xu

Rock and Soil Mechanics

The long-term train loads can result in problems such as strength attenuation, excessive cumulative settlement and even subsidence in sandy soil foundations and filling materials, which can jeopardize train operation safety. To understand the mechanism of the disease, it is necessary to explore the cumulative plastic deformation and pore water pressure characteristics of saturated sand under intermittent loading. Therefore, dynamic triaxial tests under continuous and intermittent loading with different dynamic amplitudes and confining pressures were performed. The test results showed that: (1) The cumulative plastic deformation-loading cycle curve of saturated sand exhibited a “zigzag” pattern. The intermittent effect led to …

Experimental Study On The Mechanical Response Of Buried Pipelines Under Different Subsidence Patterns, Yu Zhang, Hao Liang, Liang Lin, You Zhou, Qing-Song Zhao

Rock and Soil Mechanics

The frequent occurrence of buried pipeline accidents caused by the ground collapse and subsidence makes it urgent to carry out experimental studies on the mechanical response under different subsidence effects. A systematical survey of the pipeline strain, earth pressure and soil deformation was conducted considering the effects of ground subsidence and collapse. The result showed that due to the arching effect at the top of the pipeline, the strain and earth pressure firstly increased and then decreased with the extension of the collapse zone, while they increased as the subsidence zone extended during the collapse and settlement. In the subsidence …

Enhancing The Co2 Trapping Capacity Of Saudi Arabian Basalt Via Nanofluid Treatment: Implications For Co2 Geo-Storage, Muhammad Ali, Nurudeen Yekeen, Mirhasan Hosseini, Ghazanfer R. Abbasi, Amer Alanazi, Alireza Keshavarz, Thomas Finkbeiner, Hussein Hoteit

Research outputs 2022 to 2026

Mineralization reactions in basaltic formations have gained recent interest as an effective method for CO2 geo-storage in order to mitigate anthropogenic greenhouse gas emissions. The CO2/rock interactions, including interfacial tension and wettability, are crucial factors in determining the CO2 trapping capacity and the feasibility of CO2 geological storage in these formations. The Red Sea geological coast in Saudi Arabia has many basaltic formations, and their wetting characteristics are rarely reported in the literature. Moreover, organic acid contamination is inherent in geo-storage formations and significantly impacts their CO2 geo-storage capacities. Hence, to reverse the organic effect, the influence of various SiO2 …