Engineering Commons^™

Energy Dissipation In A Sand Damper Under Cyclic Loading, Ehab Sabi

Civil and Environmental Engineering Theses and Dissertations

Various seismic and wind engineering designs and retrofit strategies have been in development to meet structures' proper and safe operation during earthquake and wind excitation. One such method is the addition of fluid and particle dampers, such as sand dampers, in an effort to reduce excessive and dangerous displacements of structures. The present study implements the discrete element method (DEM) to assess the performance of a pressurized sand damper (PSD) and characterize the dissipated energy under cyclic loading. The idea of a PSD is to exploit the increase in shearing resistance of sand under external pressure and the associated ability …

Development Of An Excel Model To Evaluate The Stability Of Slopes, Bradley Davis

All Graduate Plan B and other Reports, Spring 1920 to Spring 2023

This objective of this study is to determine a method or tool for taking given slope stability parameters and quickly and effectively determining the factor of safety against sliding of fully softened slopes. This study evaluates the effects of soil and geometric parameters of common slopes, and models these properties in a hypothetical model. The methodology is based on a parametric analysis using the Spencer’s Method of Slices limit equilibrium analysis used in the computer program Slide2. A parametric analysis is performed to determine which soil and/or geometric properties have a high influence on slope stability. The parametric analysis is …

Continuous Moisture Measurement During Pavement Foundation Construction: Laboratory Measurements, Isaac Esteban Zuniga

Open Access Theses & Dissertations

Moisture content directly affects all properties of subgrade materials. A rapid, continuous, and accurate technique to determine moisture content during subgrade construction is the next step needed to improve the mechanistic-based quality of pavement foundations. In this study, six geomaterials were compacted to standard/modified proctor specifications and subjected to laboratory measurements to study the variations in their electromagnetic and electric properties with moisture content. The relationships between the seismic modulus, unconfined compressive strength, lightweight deflectometer, and moisture content for the same geomaterials were also established. Large-scale replicate specimens were also compacted and subjected to numerous measurements. The dielectric constant measured …

Erosion And Resuspension Of Cohesive Sediments In Coastal Louisiana, Laith Qasem Shamaileh

University of New Orleans Theses and Dissertations

The research presented in this study is motivated by the need to improve the predictions of cohesive sediment erosion and subsequent transport. In addition, the knowledge of the geotechnical engineering soil properties related to the erosion of sediments in coastal Louisiana has broad implications as these properties are used in transport models guiding the current restoration efforts. The erosion measuring device used in the study is the Cheng-Han Tasi and Wilbert Lick Shaker. Previous studies have been conducted before using the Shaker, but challenges with the calibration of the shear stress hampered the resuspension results produced by the Shaker. Therefore, …

The Living Breakwaters Pdr Efforts Econcrete Resource Analysis, Guianina Ferrari, Shervon Stephens, Calvin O. Walters Jr.

Publications and Research

On October 29, 2012, Superstorm Sandy impacted 443,000 people and caused nearly $19 billion (about $58 per person in the US) worth of damage within New York City. As part of the New York City infrastructure reparation plan, the Living Breakwaters project in Tottenville addressed coastal resilience, allocating $100M of public funds to a series of artificial breakwaters by the southwest coast of Staten Island. Each breakwater is constructed and designed to mitigate water flow in storm events. ECOncrete, a primary element of the breakwater, is a specialty cast cementitious product that is marine organism-friendly that encourages biocalcification and photosynthesis. …

Investigation Of Geopolymer Based Soil Stabilization Methods For Expedient Airfield Pavement Surfaces, Brett Albertson

All Theses

The United States Air Force (USAF) has the unique capability of being able to interdict superior airpower anywhere, at any time. However, superior airpower is only as effective as the amount of time an aircraft can spend in a particular area. The closer an aircraft can get to the mission need, the more time that can be spent in the air, or the less time that must be spent moving in and out of the operational area. Through the use of skilled and experienced men and women, the USAF is able to apply expedient and unsurfaced airfield paving techniques that …

Dynamic Behaviors Of Micp And Fiber-Treated Calcareous Sand Under Dynamic Triaxial Testing, Rui Wang, Xiao-Hua Pan, Chao-Sheng Tang, Chao L, Dian-Long Wang, Zhi-Hao Dong, Bin Shi

Rock and Soil Mechanics

To improve the liquefaction resistance of calcareous sand foundations, microbially induced calcium carbonate precipitation (MICP) technology and fiber reinforcement technology was combined to treat the calcareous sand sampled from the South China Sea. Based on dynamic triaxial tests, the dynamic behaviors of MICP-treated and fiber-reinforced calcareous sand, including dynamic strain, dynamic pore pressure, stress−strain hysteresis loop and dynamic modulus of elasticity, were analyzed. Then, the strengthening mechanism of MICP and fiber on the mechanical properties of the treated calcareous sand was explored from the microscopic point of view, based on the scanning electron microscope (SEM) test results. The results show …

Experimental Study On Internal Erosion Behaviors Under Fluctuating Hydraulic Condition Using Transparent Soil, Ze-Zhi Deng, En-Yue Ji, Gang Wang

Rock and Soil Mechanics

Internal erosion is a phenomenon that fine particles migrate through the channels within coarse matrix under seepage flow. Previous studies mainly focused on the internal erosion under steady hydraulic gradient, while the studies on the behavior and mesoscopic mechanism of internal erosion under fluctuating hydraulic condition were rarely reported. In this study, a setup of transparent soil seepage test was developed. Seepage tests on two types of soils with different internal stability were conducted under steady and fluctuating hydraulic conditions respectively to investigate the internal erosion behaviors under fluctuating hydraulic condition. The macroscopic experimental phenomenon showed that when the hydraulic …

Modification Of Linear Regression Method For Rock Shear Strength Parameters Under Triaxial Condition, Bin Li, Da-Guo Wang, Zhi-Liang He, Peng Wang

Rock and Soil Mechanics

The triaxial strength envelope of rocks is usually nonlinear, and the shear strength parameters obtained by the linear regression method (LRM) are highly sensitive to confining pressure. In order to enable LRM to consider the influence of confining pressure on the estimation of shear strength parameters, the confining pressure effect coefficient of triaxial strength of rocks is defined. An exponential function is constructed to express the relationship between the coefficient and confining pressure, which is also introduced into the correction of LRM. A linear regression method considering confining pressure effects (CCPE-LRM) is proposed. At the same time, a rationality test …

Experimental Research On Fracture Initiation Pressure Of Conventional Triaxial Slurry Fracturing In Similar Material Of Sandy Mudstone, Hua Cheng, Xiang-Yang Liu, Ru-Kang Cao, Xue-Song Wang

Rock and Soil Mechanics

To further explore the fracture initiation mechanism of fracture grouting in typical sandy mudstone from Huainan and Huaibei mining areas in China, a conventional triaxial fracture grouting test device was developed, and the model test of fracture initiation pressure of slurry fracturing in similar material of sandy mudstone was carried out. Based on the test results, the influences of rock strength and stress state on grouting fracture initiation pressure and fracture propagation pattern were analyzed, and the fracture initiation mechanism of fracture grouting in sandy mudstone was revealed. The results show that there is a positive correlation between the initiation …

Soil-Water Characteristic Of Biochar-Clay Mixture In The Full Suction Range, Ming-Yu Li, Wen-Jing Sun, Qiang Huang, De-An Sun

Rock and Soil Mechanics

Soil-water characteristic curve (SWCC) plays an important role in defining the hydro-mechanical behavior of unsaturated soils. Biochar has the properties of porous structure, high specific surface area and high adsorption. The hydraulic characteristics of biochar-amended soil may change due to the influence of natural environmental factors when applied as the cover layer of landfills. In order to study the effect of biochar content on the water retention behavior of biochar-clay mixture in full suction range, the suction of samples was controlled by vapor equilibrium technique (suction range 3–368 MPa), filter paper method (suction range 0–40 MPa) and pressure plate method …

Macro-Mesoscopic Investigation Of Cushioning Mechanism Of Recycled Concrete Aggregate Under Successive Rockfall Impacts, Yu-Chen Su, Yuan Wang, Hui-Ming Tang, Heng Zhong, Xin Li, Chao-Fu Liu, Ya-Ru L

Rock and Soil Mechanics

Cushion materials can effectively reduce the impact load acting on the rigid protective structures such as shed tunnel and improve the impact resistance of the structures. In order to investigate the variation of cushioning performance of recycled concrete aggregate (RCA) under successive impacts, drop weight impact tests and discrete element simulations are carried out. Test results show that compared with the quartz sand cushion, the transmitted load at the center of concrete shed for RCA under the first impact reduces by 83%, and it is distributed more uniformly. With the increase in the number of impacts, the cushioning performances of …

Three-Dimensional Stability Limit Analysis Of Cracked Loess Slopes, Xue-Liang Zhu, Sheng-Jun Shao, Xiao-Jun Shen, Shuai Shao, Xiao-Kang Liu

Rock and Soil Mechanics

The development of vertical cracks in loess slopes often affects slope stability. Compared with the plane strain mechanism, the slope stability analysis under the three-dimensional (3D) failure mechanism is closer to the actual slope instability. Based on the upper bound method of plastic limit analysis, different failure mechanisms (face failure, toe failure and base failure) of 3D loess slope with pre-existing cracks are considered, the energy balance equation and its dimensionless critical height expression γH/c are established, and the upper bound solution of critical height is obtained by random search method. The effects of constraint width, slope angle, internal friction …

Statistical And Regression Analyses Of Sands Stiffness In Triaxial Tests And Application Of The Results, Sharafutdinov Rafael

Rock and Soil Mechanics

The density and stress state significantly impact on the sand stiffness. Many of hardening soil models used for geotechnical computation are based on Duncan-Chang model and do not consider the influence of density on the soil stiffness. In course of triaxial compression of very dense or loose sands, the shear strains rise induces significant changes in density. In order to evaluate the effects of grain size distribution, density, and stress state on stiffness, the results of 962 isotropic triaxial tests on soil samples from 15 Moscow and Minsk construction sites were processed using statistical and regression analysis. As a result, …

Influence Of Particle Size Distribution And Initial Dry Density On The Characteristics Of Subgrade Mud Pumping, Yu Ding, Yu Jia, Xuan Wang, Jia-Sheng Zhang, Xiao-Bin Chen, Hao Luo, Yu Zhang

Rock and Soil Mechanics

The subgrade mud pumping of heavy-haul railway is widespread and harmful, which seriously affects the stability of tracks and the safety of train operation. The properties of railway subgrade soil, such as the particle gradation, the void ratio, have a significant impact on the characteristics of subgrade mud pumping under train load. In this study, a series of remolded samples consisting of silty clay and different content of Kaolin was subjected to mud pumping tests with a self-developed test model. The influence of varying particle gradations (Kaolin content) and initial dry densities (void ratio) on axial strain, excess pore water …

Numerical Investigation Of Heat Generation And Accumulation Contributing To Elevated Temperature In Msw Landfills, Alborz Fathinezhad

LSU Doctoral Dissertations

Landfills are complex geostructures which contains organic and inorganic municipal, and in some cases industrial, wastes and are expected to remain operational for long times. Due to the complex nature of physical, chemical, biological, and thermal reactions that carry on within the depths of a landfill, unexpected incidents such as elevated temperatures could become inevitable. While uncommon to happen, elevated temperatures cause health and environmental issues such as odors, rapid settlements, slope instabilities. In addition, elevated temperatures can negatively impact engineered components in composite bottom liners, cover systems, leachate collection, and gas extraction and recovery systems.

Air intrusion into municipal …

Geology-Based Shear-Wave Velocity Model Of Reference Site Conditions In South Carolina For Seismic Site Response Analysis, Camilius Amevorku

All Dissertations

Assessing earthquake hazard in the State of South Carolina is important because it is one of the most seismically active regions of the eastern United States and has experienced earthquakes of damaging levels in the historical past. Examples of these damaging seismic events are the 1886 Charleston earthquake (M 6.7 to 7.5) and the 1913 Union County earthquake (M 4.5 to 5.5).

Small-strain shear-wave velocity (V_S) is an important parameter in performing site response analysis. The deep nature of the top of reference firm rock (i.e., V_S ≥ 760 m/s or B-C boundary) due to …

Experimental Study On Influence Of Positional Relationship Between Dynamic Load And Long Axis On Impact Rockburst In An Elliptical Cavern, Yang Wang, Dong-Qiao Liu, Fu-Qiang Ren, Tian-Xiang Hu, Man-Chao He

Rock and Soil Mechanics

In order to explore the influence of the relative positional relationship between the dynamic load and the long axis of the elliptical cavern on the characteristics of impact rockburst, a cuboid sample with an elliptical hole is prepared. With two positional relationships of disturbance direction parallel or perpendicular to the long axis of the elliptical cavern, the elliptical cavern impact rockburst experiments are carried out. With the aid of video recording device, the characteristics of the impact rockburst of the elliptical cavern are discussed in terms of damage process of rockburst ejection, ejection speed, failure mode and fragment size. The …

Deterioration-Buckling Failure Mechanism Of Consequent Bedding Limestone Bank Slope In Three Gorges Reservoir Area, Guo-Qiang Yan, Yue-Ping Yin, Bo-Lin Huang, Lei Hu

Rock and Soil Mechanics

In the Wuxia section of the Three Gorges Reservoir area, it is found that there are many deformation signs of sliding-bending along the bedding bank slope, and the cyclic fluctuation of reservoir water worsens the deterioration and instability of the bank leading edge. Taking Qingshi #6 slope in the Wuxia section as an example, an laboratory generalized model is constructed to study the catastrophe mechanism of bedding limestone bank slope under the deterioration of rock mass in hydro-fluctuation belt. The research shows that: the bank slope is in a stable state as a whole for a long time before impoundment. …

Investigation Of The Influence Of Interaction Of Wraparound Geogrid-Sand On The Load Bearing-Settlement Behavior Of Strip Footings, Hussein Ahmad, Ahmad Mahboubi, Ali Noorzad, Mohammad Hosein Hoseini

Rock and Soil Mechanics

The use of high-quality materials and the strengthening of soil layers, especially in areas with poor bedding, are among the most important factors in stabilizing and achieving the useful life of building structure. An experimental study on a strip footing coated with unreinforced, geogrid-reinforced, and folded geogrid layers of fine sand is presented in this paper. Testing procedures evaluate variables such as the number of planar geogrid layers, the position of the folded geogrid within the soil, the thickness of the geogrid folded layer, the overlap lengths of a folded geogrid, the spacing within folded layers of geogrid, and several …

Study Of Multi-Parameter Dominant Grouping Method Of Rock Mass Discontinuity Based On The Principal Component Analysis, Fu-Rui Dong, Shu-Hong Wang, Qin-Kuan Hou

Rock and Soil Mechanics

Statistical analysis and clustering of discontinuities existing in rock mass are the basis of rock mass engineering stability analysis. Considering that the mechanical and hydraulic properties of discontinuities are affected by many factors such as occurrence, trace length, aperture, roughness, and filling state, a multi-parameter dominant grouping method of rock mass discontinuities based on principal component analysis is proposed. Firstly, the principal component analysis method is used to select the criterion of the dominant grouping and calculate the weight value of its participation in similarity measurement. Secondly, the global optimal initial clustering center of the fuzzy C-means clustering algorithm is …

Mechanical Properties Of Slag-Fly Ash Based Geopolymer Stabilized Sandy Soil, Jin-Jin Zhang, Bo Li, Chuang Yu, Mao-Yu Zhang

Rock and Soil Mechanics

Silicate cement as a conventional soil curing agent has problems of high energy consumption and high emissions, and researchers have been seeking a more economical and environmentally friendly alternative to cement. In this study, geopolymers based on ground granulated blast-furnace slag (GGBS) and fly ash (FA) were used to reinforce sandy soils, and the effects of different factors on the mechanical properties of geopolymer stabilized sandy soils were investigated by adjusting the type and ratio of exciter, slag-fly ash ratio, water-cement ratio, and curing conditions. The specimens were studied in depth by unconfined compressive strength (UCS) test, electron computed tomography …

Experimental Study Of Fracture Dynamic Evolution Process Of Grouted Specimen Under Uniaxial Compression Based On Ct Scanning, Chang-Xing Zhu, Jia-Xin Sun, Yan-Wei Wang

Rock and Soil Mechanics

To study the fracture dynamic evolution process of grouted specimens under loading conditions, the graded gravel grouted specimen was periodically scanned during the uniaxial compression damage process using a CT scanning system. Based on the image reconstruction technique, the spatial visualization of the fracture structure inside the test grouted specimen block is achieved, and the structural characteristic parameters are characterized quantitatively such as the number and volume of fractures. The gray value and fractal dimension of the CT slices are calculated using Python programming to analyze the mesoscale damage extent at different loading stages of the grouted specimen. It is …

Application Of Nonlinear Soil Resistance-Pile Lateral Displacement Curve Based On Pasternak Foundation Model In Foundation Pit Retaining Piles, Yan-Peng Zhu, Lin-Ping Wu, Duo-Bang Shi, Zhuang-Fu Zhao, Xiang-Xiang L, Xin-Guo Duan

Rock and Soil Mechanics

As a direct retaining structure in the process of foundation pit excavation, the internal force and deformation of pile under horizontal load have great influence on the safety and economy of foundation pit engineering. In order to calculate the internal force and deformation of the supporting pile more accurately, the nonlinear foundation reaction modulus is obtained according to the nonlinear soil resistance-pile lateral displacement (p−y) curve of pile-soil interaction. At the same time, the Pasternak two-parameter foundation model is introduced to fully consider the continuity of pile side soil deformation. The differential equation of retaining pile deflection considering pile-anchor deformation …

Experimental Investigation Of Clay Aggregate And Granular Biofilm Behavior, Tao Jiang

Doctoral Dissertations

Clay minerals are a class of phyllosilicates as the major solid constituents in cohesive fine-grained soils (e.g., clays). Owing to their tiny size (i.e., < 2 μm), high aspect ratio, and active surface properties that inherit from the geological process, clay minerals can extensively interact with other suspended matter (e.g., exoployemers, microorganisms) and dissolved ions via the process of flocculation and aggregation, resulting in the formation of larger, porous cohesive particulate aggregates or flocs. Such a complex mechanism of microscale particle interaction generates significant challenges for understanding the bulk clay behavior as a particulate system. In order to better characterize the flocculation and aggregation of clay minerals under various stimuli and to understand the underlying mechanism of particle interactions, particle/aggregate size kinetics of flocculated suspensions of illite, a representative 2:1 clay mineral abundant in marine soils, are studied with varied ionic strength induced by monovalent salt (NaCl), pH, and hydrodynamic shearing in the first phase of this research. Furthermore, a new statistical data binning method termed “bin size index” (BSI) was employed to determine the probability density function (PDF) distributions of flocculated illite suspensions. The statistical results demonstrate that the size kinetics of flocculated illite suspensions is chiefly controlled by the face-to-face and edge-to-face interparticle interactions under the mutual effects of ionic strength and pH, while the hydrodynamic shearing has minimal effects on the variation of particle size groups. In the second phase of this research, the mechanics of clay aggregates are studied using an innovative measurement technique and analytical approach. Individual clay minerals prepared with different mineralogy and salinities are tested via unconfined compression, which shows that the increasing ionic strength can improve the strength and stiffness of clay aggregates, which are further affected by the mineralogical compositions and dominant microfabric in different water chemistry. In the final phase of this research, a collaborative study with an environmental engineer on an NSF CAREER project was conducted to investigate the mechanical behavior of macroscale, light-induced oxygenic granules (biofilm aggregates) using the same technique and analytics developed for the individual clay aggregates. The findings are expected to provide reference values to subsequent studies and engineering practices associated with the water treatment process.

Randomly Generating The 3d Mesostructure Of Soil Rock Mixtures Based On The Full In Situ Digital Image Processed Information, Zhengsheng Li, Haiyang Yi, Cheng Zhu, Zhuang Zhuo, Guoshuan Liu

Henry M. Rowan College of Engineering Faculty Scholarship

Understanding the occurrence and evolution of geological disasters, such as landslides and debris flows, is facilitated by research on the performance of soil rock mixes (SRM). Recently, more and more researchers have been interested in studying the mesostructure reconstruction process of SRM. The present mesostructure generation approaches, however, have several weaknesses. One of the weaknesses is that they do not consider the impact of particle shape and therefore cannot ensure similarity to the in situ SRMs. In this study, a new mesostructure generation method that randomly generates SRMs based on the full in situ digital image processing (DIP) information is …

Inversion Iterative Correction Method For Estimating Shear Strength Of Rock And Soil Mass In Slope Engineering, Wei Jiang, Ye Ouyang, Jin-Zhou Yan, Zhi-Jian Wang, Li-Peng Liu

Rock and Soil Mechanics

For the slopes that have failed or deformed significantly, the shear strength of rock and soil mass is frequently inversely estimated based on a factor of safety assumed. For the slope with a sliding surface passing through multi-layer rock and soil mass, it is unreasonable to achieve this goal by blind trial. To solve this issue, back propagation (BP) neural network is constructed using shear strength of multi-layer rock and soil mass as the input, and the factor of safety of slope, the entrance and exit positions of the sliding surface obtained by Geoslope as the outputs. Then, based on …

Research Progress On Support Technology And Methods For Soft Rock With Large Deformation Hazards In China, Yong-Shui Kang, Zhi Geng, Quan-Sheng Liu, Bin Liu, Yuan-Guang Zhu

Rock and Soil Mechanics

Soft rock engineering is involved in many important engineering fields such as mining, hydraulic engineering, transportation and national defense. With the increase of mining depth and the development of tunnel engineering, a large number of tunnels and roadways need to pass through soft rock formations, in which the problems such as high geostress and broken and weak surrounding rocks are prominent. Large deformation disasters of soft rocks pose serious threats to engineering safety and cause enormeous economic losses. In this paper, the research progress on soft rock support in China is first reviewed, and the research status quo of technology …

Elastic-Plastic Deformation Of Surrounding Rocks Under Graded Yielding Support Of Tunnel, Jian-Hua Dong, Bin Xu, Xiao-Lei Wu, Bo Lian

Rock and Soil Mechanics

In order to solve the failure of support structure of tunnel in high stress soft rock, based on the principle of reasonably releasing the stress in surrounding rocks and reducing the stress of support structure, a hydraulic tunnel graded yielding support structure is proposed. Considering the spatial effect of the excavation surface and the strain softening condition of the surrounding rocks, by analyzing the attenuation law of the virtual supporting force, the static balance equation of stress in the surrounding rocks, the virtual support force and the support reaction force is established. The synergy between the supporting structure and the …

Slope Stability Of An Unsaturated Embankment With And Without Natural Pore Water Salinity Subjected To Rainfall Infiltration, Sadeghi Hamed, Kolahdooz Ali, Ahmadi Mohammad-Mehdi

Rock and Soil Mechanics

Natural soils contain a certain amount of salt in the form of dissolved ions or electrically charged atoms, originated from the long-term erosion by acidic rainwater. The dissolved salt poses an extra osmotic water potential being normally neglected in laboratory measurements and numerical analyses. However, ignorance of salinity may result in overestimation of stability, and the design may not be as conservative as thought. Therefore, this research aims to first experimentally examine the influence of pore water salinity on water retention curve and saturated permeability of natural dispersive loess under saline and desalinated conditions. Second, the measured parameters are used …