Engineering Commons^™

The Stability Of Nanobubbles And Its Application In Contaminated Sediment Treatment, Shaini Dilsha Aluthgun Hewage

Dissertations

This dissertation consists of two sections. First, nanobubbles' stability and behavior are studied using experimental and theoretical approaches. Second, nanobubbles application combined with ultrasound to remediate contaminated sediments is discussed.

The stability study consists of four sections. (i). Laboratory investigation to determine bubble size distributions and zeta potentials for different gases, pH levels, temperatures, and salt conditions. (ii). A theoretical study based on the diffused double layer theory to explain nanobubbles' behavior in different NaCl concentrations. (iii). Nanobubbles' stability in electrolyte solutions under different ion valencies using deionized water, NaCl, Na₂SO₄, Na₃PO₄, …

Triple-Shear Failure Criteria And Experimental Verification For Unsaturated Soils, Hao Chen, Xiao-Rong Hu

Rock and Soil Mechanics

Based on the triple-shear failure criterion of materials and the mechanical properties of unsaturated soils, the triple-shear failure criteria of the single stress variable and the double stress variable for unsaturated soils are put forward, and their characteristics are analyzed. The results show that the existing failure criteria for unsaturated soils can be interpreted approximately with the new criteria by changing the influence coefficient b of the principal stress. For loci on the π plane, the failure criteria proposed in this paper cover all the convex regions from the inner boundary of the single-shear failure criterion to the outer boundary …

Intelligent Recognition Of Tunnel Stratum Based On Advanced Drilling Tests, Yu-Wei Fang, Zhen-Jun Wu, Qian Sheng, Hua Tang, Dong-Cai Liang

Rock and Soil Mechanics

The reliable recognition of strata in front of tunnel face is significant for the stability and safety of the tunnel engineering project. Traditional advanced geological forecasting methods could not ensure high identification accuracy, low cost and short construction time simultaneously, and they can’t satisfy the universality of stratum identification under different geological conditions. The advanced forecasting efficiency could be significantly enhanced if the drilling data of surrounding rocks in front of the tunnel face can be obtained while performing the conventional advanced borehole to attain the rock conditions at different drilling depths in real time, which would be convenient and …

Study On Constitutive Model Of Fractured Rock Mass Based On Statistical Strength Theory, Wei Gao, Cheng-Jie Hu, Tian-Yang He, Xin Chen, Cong Zhou, Shuang Cui

Rock and Soil Mechanics

With the aid of damage mechanics and on the basis of statistical strength theory, a method for establishing the constitutive model of deep fractured rock mass is proposed and verified by laboratory and numerical tests. The fractured rock mass is divided into numerous micro-cubes. The strength of micro-cubes is related to the fracture degree and the strength of each micro-cube is randomly distributed. Thus the strength can be used to reflect the fracture degree of the rock mass. Among them, based on the fact that the work done by friction between fracture surfaces is equal to the strain energy released …

Study On Solid-Liquid Phase Transition Characteristics Of Saturated Sand Based On Large Shaking Table Test On Free Field, Cheng-Shun Xu, Peng-Fei Dou, Xiu-Li Du, Su Chen, Jun-Yan Han

Rock and Soil Mechanics

Based on the large shaking table test of saturated sand on the free field, the dynamic shear stress–strain response of the foundation soil model was obtained by using the linear interpolation method according to the data from accelerometer arrays. At the same time, the concepts of apparent viscosity and zero shear viscosity of non-Newtonian fluid based on the assumption of hydrodynamic theory were introduced to study the characteristics and behaviors of shear thinning after site liquefaction. The characteristics of solid-liquid phase transition of saturated sand under seismic load were studied. Results showed that when the saturated sand was stimulated by …

A Theoretical Study Of Porosity Characteristics On The Excavation Face Of Slurry Shield In Sand Stratum, Jia-Hua Mao, Da-Jun Yuan, Jiang-Xiao Yang, Bing Zhang

Rock and Soil Mechanics

To maintain the stability of excavation face in slurry shield, a filter cake must be timely formed during the excavation work. With the filter cake, the slurry pressure can counteract the earth pressure and water pressure in the excavation stratum. In this study, a mathematical model of slurry penetration under constant pressure in sand stratum is established by considering the filtration effect. By means of this model, the influence of penetration time, slurry concentration, slurry pressure and initial stratum porosity on soil porosity and filter cake formation is analyzed. Combining the periodic disturbance of cutting-tools, the variation of soil porosity …

Dynamic Response Of Pile Foundation Under Pile-Soil-Fault Coupling Effect In Meizoseismal Area, Jing-Bin He, Zhong-Ju Feng, Yun-Xiu Dong, Hai-Bo Hu, Chuang Liu, Sui-Zhu Guo, Cong Zhang, Min Wu, Zhen Wang

Rock and Soil Mechanics

In order to study the dynamic response characteristics of pile foundation under the pile-soil-fault coupling effect, four different types of seismic waves with the peak acceleration of 0.35g are selected for shaking table test. The acceleration response, relative displacement of pile top, bending moment of pile body and damage of pile foundation under different types of seismic waves are studied. The test results show that the parameters of the pile in hanging wall are obviously larger than those in the footwall of the fault, showing the hanging wall effect. The peak acceleration of pile top is greater than that of …

Continuum-Discontinuum Simulation Of Effects Of Internal Friction Angle On Local Fracture Of Circular Cavern Surrounding Rock Under Hydrostatic Pressure, Xue-Yuan Bai, Xue-Bin Wang, Qin Shu

Rock and Soil Mechanics

In order to simulate the transition of rock from continua to discontinua more accurately and reduce the mesh dependence, an element splitting method is developed based on the continuum-discontinuum method where the Lagrangian element method is coupled with discrete element method. The computational domain is discretized into high-precision quadrilateral elements; after cracking, the cracks can propagate along the diagonal lines of quadrilateral elements and the edges of triangular or quadrilateral elements. Deformation-cracking processes of the Brazilian disc rock specimen, uniaxial compression rock specimen and surrounding rocks under hydrostatic pressure are simulated. The following results are found. (1) For the Brazilian …

Stability Analysis Of An Underground Powerhouse On The Left Bank Of The Baihetan Hydropower Station Based On Discrete Element Simulation And Microseismic Monitoring, Hao-Yu Mao, Nu-Wen Xu, Biao Li, Yi-Lin Fan, Jia-Yao Wu, Guo-Tao Meng

Rock and Soil Mechanics

To investigate the stability of the surrounding rock during excavation process of the underground caverns at the Baihetan hydropower station, effects of excavation unloading on the deformation and failure of the surrounding rock using the numerical simulation software 3DEC based on DEM (discrete element method) are analyzed. The microseismic monitoring technology is introduced to monitor and analyze micro-fracture evolution inside the surrounding rock of the caverns in real time, and the numerical simulation results are compared with the microseismic monitoring data. In order to verify the accuracy of numerical simulation and microseismic monitoring results, the spatiotemporal evolution law of the …

Study On Bearing Behavior Of Flexible Single Pile Subject To Horizontal And Uplift Combined Load, Lei Zhang, Wei-Shen Hai, Hao Gan, Wei-Ping Cao, Tie-Hang Wang

Rock and Soil Mechanics

In order to study the bearing behavior of a flexible single pile under combined horizontal and uplift loading, two groups of structural testing, comprised of 6 pile models in total have been carried out. The results show that for a flexible single pile, pre-applied uplift load with a magnitude smaller than half of pure uplifting capacity(Tu1) lead to significant improvement of ultimate horizontal bearing capacity, achieving greater horizontal resistance compared to pure ultimate horizontal bearing capacity (Hu1) Additionally, it has been observed that this horizontal bearing capacity increases initially but decreases subsequently under further increasing uplift load. This load increasing …

An Elastoplastic Model For Energy Soils Considering Filling And Bonding Effects, Qing-Meng Yuan, Liang Kong, Ya-Peng Zhao

Rock and Soil Mechanics

The filling and bonding effects of hydrate increase the compactness and strength for gas hydrate-bearing sediments(GHBS), which makes the GHBS exhibiting properties similar to dense sand or cemented soil. Under the frame of unified hardening model of clay and sand (CSUH model), the mechanical properties of GHBS are summarized firstly, and a compressive hardening parameter is introduced to describe the isotropic compression characteristics of GHBS under the double influences of filling and bonding of hydrate. A bonding parameter is put forward to modify the yield function, and an evolution rule of bonding effect is also proposed. The state parameters are …

Integration And High Precision Intelligence Microseismic Monitoring Technology And Its Application In Deep Rock Engineering, Bing-Rui Chen, Xia-Ting Feng, Qi-Qing Fu, Bo Wang, Xin-Hao Zhu, Tao Li, Cai-Ping Lu, Huan Xia

Rock and Soil Mechanics

It has been popular and difficult for scientists and engineers to acquire more microseismic information, automatically identify microseismic data of rock rupture, locate the location of rock rupture automatically and accurately, and provide theoretical and technical support for disaster analysis, early warning, and prevention and control. In view of these difficulties, an integrated and high precision intelligence microseismic monitoring technology was developed. In the microseismic monitoring technology, several innovation techniques are developed, which include that a sensing-acquisition-transmission technology was integrated; the acquisition technology with noise reduction of 32 bits A/D coupled with electric components was established; integrated identification method of …

Feasibility Of Geothermal Energy Piles In New Orleans Alluvial Soils, Patrick A. Thurmond

University of New Orleans Theses and Dissertations

Geothermal energy piles offer the benefits of modifying existing construction practices to reduce costs associated with heating and cooling. A major obstacle today in effective utilization of these systems is a general lack of site-specific data on the thermal properties of subsoils. To maximize the potential efficiency of these systems, engineers require an understanding of the potential impact of this technology on existing foundation design methodology as well as a means for quantifying potential heat transfer through soil by determination of the soil’s thermal conductivity. This study examines the feasibility of energy piles with a focus on alluvial soils found …

Geo-Structural Analysis Of Integral Abutment Bridges, Biyi Li

Electronic Thesis and Dissertation Repository

Integral abutment bridges are jointless bridges where bridge decks and girders are integrated with abutments. The longitudinal displacements and rotations of the bridge are partially accommodated by the soil-pile system wherein the soil surrounding the piles generates active and reactive lateral forces when the piles deflect due to the movement of the superstructure. Since the soil stress-strain responses are inherently nonlinear, the pile deflection and the soil stiffness are interdependent. Consequently, evaluating soil-pile interactions requires a detailed geo-structural analysis. There are two common approaches used to idealize the soil-pile interactions for laterally loaded piles: the p-y and continuum mechanics approaches …

Сharacteristics Mineral Resource Base Of Madagascar, A. E. Vorobyev, K. A. Vorobyov, S.A. Ndriambanuna, L.E. Schesnyak

Gorniy vestnik Uzbekistana

The main characteristics of the mineral resource base of Madagascar with details of coal, iron ore, non-ferrous metals, uranium, rare metals and gold are considered. In the gold-ore mineral base of Madagascar, coastal placers are of particular potential interest. Foreign mining companies and local crafts are described. The transition to the development of coastal gold placers is proposed

Laboratory Testing And Mechanistic Analysis Of Treated Subgrade Soils, Hari Kumar Reddy Yarrapureddi

Civil Engineering Theses

Calcium-based stabilizing agents such as cement and lime have been extensively used to improve the engineering properties of base and subgrade layers of pavement systems. Recently, polymers and chemical stabilizers have become popular due to cost efficiency, ease of application, and fast curing times. In this study, California Bearing Ratio (CBR) values of polymer and chemical treated soils were compared with the CBR values of soils treated with conventional stabilizers. Parametric sensitivity analyses was carried out on key parameters including the type of subgrade soil, stabilizing agent, stabilizing agent treatment levels, and moisture conditioning. Additionally, numerical analyses was performed to …

Expanding The Concept Of Comprehensive Area Ratio Parameter To The South-Central States Towards Simplifying The Structural Evaluation Of Flexible Pavements At The Network Level, Nitish R. Bastola

Civil Engineering Theses

The surface deflection bowl data collected through Non-Destructive Testing (NDT) has been widely utilized by various Department of Transportation (DOTs) in the South-Central States and other places. The primary purpose of using deflection-based NDTs in network-level assessment is to identify a weak pavement section that requires further analysis at the project level. The falling weight deflectometer (FWD) test is one of the common NDT based tests utilized by highway agencies in assessing the performance of the flexible pavement. However, a robust method to evaluate pavement sections utilizing FWD data from all the sensors are seldom developed. There is always a …

Relationships Between In-Situ Tests And Soil Cyclic Strength For Earthquake Hazard Characterization In The Pacific Northwest, Tanner Scott Bryantt

Dissertations and Theses

Strong earthquake shaking is a natural hazard threat in the Pacific Northwest. Soil failure due to strong earthquake shaking -- known as cyclic soil failure or liquefaction -- is expected to cause large ground deformations and damage to roads, bridges, and other civil infrastructure. Cyclic soil strength (CRR) is often characterized with in-situ geotechnical tests including the cone penetration test (CPT). Relationships between CRR and in-situ test data are not well established for soils in the Pacific Northwest. Portland State University, in partnership with New Albion Geotechnical has compiled a database of cyclic lab tests for Pacific Northwest soils to …

Durability Of Entrapped Gas In Quasi-Saturated Porous Media: Two Geotechnical Perspectives, Babak Mahmoodichanzab

Electronic Theses and Dissertations

Entrapped gas bubbles in quasi-saturated porous media are of practical importance in the field of science and engineering. Gas bubbles, which may occur naturally or be introduced artificially, significantly influence the mechanical behavior of soil. In this study, the durability of gas is examined from two geotechnical engineering perspectives. In the field of geotechnics, the artificial introduction of gas is being considered, as it has been widely recognized that entrapped gas, even in nearly-saturated sediments, has an appreciable influence on soil’s mechanical behavior. Entrapped gas bubbles in quasi-saturated sediments significantly increase the pore fluid compressibility and suppress the generation of …

3d Study Of Gas Hydrate Formation And Dissociation In Porous Media And Dem Modeling Of Granular Materials, Zaher Jarrar

Doctoral Dissertations

Natural methane gas hydrates availability and ongoing rise in demand for energy, motivated researchers to consider gas hydrates as a potential energy source. Production of methane from hydrate-bearing sediments requires hydrate dissociation for releasing mobile methane gas in sediments prior to gas production operations. Fines may migrate through or clog the pore space of sandy sediments depending on the geometry and topology of the pore space. This dissertation employs unique in situ experiments and techniques to gain a comprehensive understanding of the associated physical processes (such as fines migration, clogging and gas driven fracture) and validation of hydrate dissociation models’ …

Cement Stabilized Crushed Stone Base Course Strength And Stiffness Analysis, Andrew Deschenes

Graduate Theses and Dissertations

Approximately 70 – 80% of state departments of transportations (DOTs) utilize the 1993 AASTHO Guide for Design of Pavement Structures (1993 AASHTO) [1] for structural design of pavements. A growing portion of DOT’s are beginning to implement the Mechanistic-Empirical Pavement Design Guide (MEPDG), referred to as AASHTOWare Pavement ME [2]. The 1993 AASHTO flexible guide applies empirically derived unitless strength values referred to as structural layer coefficients and structural numbers (SN) to pavement thickness and pavement types. The 1993 AASHTO rigid flexible guide utilizes the depth and strength of the concrete pavement, with the composite spring constant (kc), which is …

Effect Of Citric Acid On Slump, Compressive Strength, And Setting Time Of Belitic Calcium Sulfoaluminate Concrete, Israel Aguilar Rosero

Graduate Theses and Dissertations

Belitic calcium sulfoaluminate (BCSA) cement has well established advantages related to fast setting time, fast strength gain, long-term strengths, shrinkage, and sustainability. Due to its fast setting and hardening, this type of cement has historically been used to repair concrete structures, highways, and runways. This work provides much needed guidance on establishing mix design criteria for BCSA cement. Guidance is also given on the effects of set retarders on strength, slump, and setting times. Citric acid and a phosphonic acid-based admixture were tested as retarders for different concrete mixtures. Three studies were performed. In the slump study five different water …

In-Situ Fluid Injections To Achieve Bio-Stimulated Calcite Precipitation In Expansive Soils, Anish Pathak

Boise State University Theses and Dissertations

Expansive soils undergo vast changes in volume when subject to change in water contents and cause damages to infrastructures across the world. Traditional methods of tackling the problem of expansive soils using cement or lime are environmentally unfriendly and expensive. Microbial Induced Calcite Precipitation (MICP) is a new method which uses bacteria in the soil to precipitate CaCO3 (calcite) and improve the engineering properties of soils. Various laboratory studies have shown that this method can be applied successfully to treat expansive soils, but the field application of the method have barely been studied.

To study the applicability of MICP in …

Incorporating Shear Resistance Into Debris Flow Triggering Model Statistics, Noah J. Lyman

Master's Theses

Several regions of the Western United States utilize statistical binary classification models to predict and manage debris flow initiation probability after wildfires. As the occurrence of wildfires and large intensity rainfall events increase, so has the frequency in which development occurs in the steep and mountainous terrain where these events arise. This resulting intersection brings with it an increasing need to derive improved results from existing models, or develop new models, to reduce the economic and human impacts that debris flows may bring. Any development or change to these models could also theoretically increase the ease of collection, processing, and …

Hydrogen Wettability Of Sandstone Reservoirs, Stefan Iglauer, Muhammad Ali, Alireza Keshavarz

Research Datasets

Data set include the data for contact angle data as a function of pressure, temperature and stearic acid concentration in H₂. One exemplary figure is also provided for contact angle measurement in H₂ atmosphere.

Experimental Study On Surrounding Rock Deformation And Acoustic Emission Characteristics Of Rectangular Roadway Under Different Loads, Gong-Yu Hou, Hao-Yong Jing, Jin-Ping Liang, Jin-Xin Tan, Yong-Kang Zhang, Xi Yang, Xin Xie

Rock and Soil Mechanics

To investigate the unloading deformation, failure and acoustic emission characteristics during excavation of rectangular roadway under different initial geostresses, excavation unloading model tests were carried out on casted surrounding-rock specimens made of cement mortar. The deformation and failure characteristics of the roof, corner and surrounding rock as well as the evolution characteristics of AE impact count, damage variable and frequency spectrum were obtained. Experimental results showed that: 1) The failure of rectangular roadway was mainly caused by the radial tension strain of the roof and surrounding rock, and the tangential compression strain of the corner. The deformation characteristics of the …

Experimental Study On Critical Dynamic Stress Of Coarse-Grained Soil In Railway Subgrade

Rock and Soil Mechanics

The coarse-grained soil is widely used as the filling in the railway subgrade, which is directly subjected to the long-term effect of the dynamic cyclic train loads transmitted from the track structure. Investigation of its dynamic behavior and plastic deformation characteristics under the dynamic train loads may provide ideas for the subgrade performance evaluation and settlement control. GDS dynamic triaxial tests were used to investigate the dynamic response of coarse-grained soil in railway subgrade. By introducing the plastic strain rate and shakedown theory, the evolution law of axial plastic strain of subgrade under different frequencies, confining pressures and cyclic dynamic …

Experimental Study On Evolution Characteristics Of Water And Mud Inrush In Fault Fractured Zones, Qing-Yan Zhang, Wei-Zhong Chen, Jing-Qiang Yuan, Liu-Qi Liu-Qi, Chi Rong

Rock and Soil Mechanics

To investigate the mechanism of water and mud inrush in water-rich fault fracture zones, a large-scale indoor water and mud inrush test system considering mass transfer and geostress state is developed. The simulation test of water and mud inrush disasters evolution process in the fault fracture zone with different hydraulic loading modes and medium parameters of fracture zones are carried out using the device. Some findings are as follows: 1) Evolution of water and mud inrush disasters in fault fractured zones is a strong coupling process of seepage and erosion. In the beginning, fine particles in the filling of fracture …

Quantitative Research On Morphological Characteristics Of Hysteretic Curves Of Remolded Weak Expansive Soil Under Cyclic Loading, Xin-Shan Zhuang, Han-Wen Zhao, Jun-Xiang Wang, Yong-Jie Huang, Zhi Hu

Rock and Soil Mechanics

A series of cyclic triaxial tests is conducted by GDS apparatus to investigate the effects of confining pressure, loading frequency, consolidation stress ratio on the hysteretic curves of the remolded weak expansive soil under multi-step loadings and single-step loadings respectively. Morphological characteristics of hysteretic curves are quantitatively described by three parameters, namely, the area S of the hysteretic curve, the slope of curve k, center offset distance d of adjacent hysteretic curves, and the degree of closure εp. The results show that the S, d and εp of the hysteretic curve of weak expansive soils increase nonlinearly with the increase …

Analysis Of The Nonlinearity Of Coefficient Of Earth Pressure At Rest And Its Calculation Method For Coarse-Grained Soils, Zhao-Sheng Yu, Xiao-Bin Chen, Jia-Sheng Zhang, Liang Dong, M S Abdoulkader

Rock and Soil Mechanics

The acquisition of a precise coefficient of earth pressure at rest (K0) is very important for earth pressure calculation, and the study of nonlinear characteristics of K0 has great practical significance. Nevertheless, the research on nonlinearity of K0 for coarse-grained soils has long been neglected. To fill the gap, this study presents a detailed analysis of the nonlinearity characteristics of K0 for coarse-grained soils. Based on the incremental stress-strain relation of Duncan-Chang model, we establish the mathematical formula of K0, and the sensitivity analysis of the K0 formula is presented. The proposed method is applied to predict the K0 of …