Engineering Commons^™

Study On Anisotropic Permeability Model For Mixed Kaolin-Montmori- Llonite Clays, Jie Xu, Jian Zhou, Ling-Hui Luo, Liang-Gui Yu

Rock and Soil Mechanics

A perfect anisotropic permeability model is helpful to guide the drainage and grouting scheme of underground buildings during construction and operation period. To study permeability anisotropy model, mixed kaolinite-montmorillonite clays were used in a series of permeation experiments by triaxial permeameter, and the development of anisotropic permeability model was attempted from both macroscopic and microscopic perspectives. The results show that: as the amount of bentonite increases, the small pores increase, but the large pores decrease; as the consolidation stress increases, all pores decrease, and the maximum pore size decreases. Macroscopically there is no correlation between the void ratio considering the …

Experimental And Model Research On Shear Creep Of Granite Under Freeze-Thaw Cycles, Feng-Rui Zhang, An-Nan Jiang, Xiu-Rong Yang, Fa -Yi Shen

Rock and Soil Mechanics

To study the effect of freeze-thaw on the shear creep characteristics of engineering rocks in cold regions, the granite samples from Huibai tunnel in Jilin province were taken as the research object, and the microscopic characteristics and shear creep tests of samples under different freeze-thaw cycles were carried out. The results show that: 1) With the increase of freeze-thaw cycles, the cracks and voids in the samples develop continuously, and the damage of rock surface becomes more and more obvious. 2) The pores in the sample are mainly composed of small and medium pores, and the porosity increases nonlinearly with …

Experimental Investigation Of Accelerated Failure Of Creep Rock Induced By Impact Disturbance, Qing-Yuan Wang, Jie Liu, Pei-Tao Wang, Fei Liu

Rock and Soil Mechanics

Rockmass may be in a creep state for a long time during underground mining. The failure progress of surrounding rock mass may be accelerated due to the mining disturbance. The rockmass failure is usually later than the mining activities and shows an obvious time lag effect, which brings difficulty in predicting the occurrence of engineering disaster. Given this problem, impact-creep tests of rock specimens were conducted under multi-cycle drop weight using a rock rheology-impact test machine. The changing law of axial strain of sandstone specimens was analyzed. The influence of creep state, impact times of drop weight, and impact energy …

Experimental Investigation On The Dynamic Response Of Pile Group Foundation On Liquefiable Ground Subjected To Horizontal And Vertical Earthquake Excitations, Heng-Yuan Zhang, De-Ling Qian, Chao Shen, Qi-Quan Dai

Rock and Soil Mechanics

To investigate the dynamic response of pile group foundation on liquefiable ground subjected to horizontal and vertical (bidirectional) coupling earthquake excitations, a shaking table model test for a dynamic interaction system with liquefiable ground –pile group foundation–frame tube structure was conducted. Different types of earthquake motions were selected as the excitations for the shaking table test, and then the influence of bidirectional coupling earthquake excitations on the dynamic response of liquefiable ground and pile group foundation were analyzed by comparing the test results of soil acceleration, excess pore water pressure and pile group strain subjected to horizontal unidirectional and bidirectional …

Development And Application Of Contact Algorithms For Rock Shear Fracture Surface, Qiu-Feng Ma, Yue-Ping Qin, Tian-Bai Zhou, Xiao-Bin Yang

Rock and Soil Mechanics

To overcome the inefficiency of existing numerical algorithms in calculating the contact slip law of complex fracture surfaces, a new numerical calculation algorithm was proposed by adoption of the idea of boundary element method. In this algorithm, all nodes were located at the boundary of rock blocks, and the interaction force between rock blocks and the displacement of rock blocks were calculated by using the explicit differential method. The algorithm was validated by two simulation experiments, i.e. “ball sliding on paraboloid” and “dumbbell on the inclined plane”. The results show the algorithm can accurately describe the contact between objects and …

Study On The Influence Of Bedding Plane On The Fracturing Behavior Of Sandstone, Bin Li, Da Huang, Wen-Zhu Ma

Rock and Soil Mechanics

The mechanical behavior of layered stone is much influenced by the weak bedding planes. To further explore how the layered structure influences the fracture characteristic of layered sandstone, a series of three-point-bending tests on sandstone specimens with different inclination angles was conducted and the anisotropy of fracture toughness and fracture pattern were discussed. Then a numerical model based on cohesive elements was proposed to simulate the fracture of semi-circular sandstone specimens under three-point-bending test and the effects of bedding strength on the fracturing behavior of semi-circular bending(SCB) specimens with different inclination angles were discussed by simulation with the proposed model. …

Analysis Of Energy Evolution During The Step Loading And Unloading Creep Experiments Of Sandstone, Chao Han, De-Peng Pang, De-Jian Li

Rock and Soil Mechanics

The uniaxial step loading and unloading creep experiments were conducted on the sandstone samples from Shaanxi Province to analyze the law of energy evolution of the samples during the process of deformation and failure. The results show that with the increase of cyclic series, the dissipation energy of each grade exhibits a nonlinear increase and the plastic strain energy of each grade is relatively stable. The dissipation energy exceeding plastic strain energy can be regarded as a precursor energy characteristic of the sample failure. By defining the correlation coefficient and establishing the relationship between energy and deformation, it can be …

Evolution Law Of Pore-Size Distribution In Soil-Water Retention Test, Geng Niu, Long-Tan Shao, De-An Sun, Chang-Fu Wei, Xiao-Xia Guo, Hua Xu

Rock and Soil Mechanics

This paper is to measure the soil-water retention curves (SWRC) of undisturbed and compacted soil specimens and compare the differences in measured data between these two soils. The mercury intrusion porosimetry (MIP) tests are conducted to explore the difference in the pore size distributions (PSD) between the undisturbed and compacted specimens and investigate the evolution law of PSD during drying. By considering shrinkage during drying, the basic parameters of SWRC can be determined based on the PSD. The results show that the undisturbed specimens in the wide suction range exhibit a unimodal PSD. The saturated compacted-specimen exhibits a unimodal PSD, …

Methods Of Determining The Minimum Number Of Samples For Statistical Measurement Of Rock Joint Roughness, Qin-Kuan Hou, Rui Yong, Shi-Gui Du, Min-Na Xu, Ze-Min Cao

Rock and Soil Mechanics

The rock joint roughness has many characteristics like heterogeneity, anisotropy, nonuniformity and scale effect. In engineering practice, different statistical methods are utilized for analyzing the rock joint roughness due to its uncertainty. However, previous studies often neglected the impact of insufficient samples on statistical results. To solve the problem that reasonable number of samples cannot be determined during the statistical measurement of joint roughness, the methods based on the coefficient of class ratio analysis and the simple random sampling principle are proposed for determining the minimum number of samples (MNS), respectively. In the case study, the MNS of statistical measurements …

Study Of Ground Motion Effect Of Trapezoidal Valley Site Based On Centrifuge Shaking Table Test, Ping Li, Yu-Dong Zhang, Tao Bo, Jun-Ru Gu, Sheng Zhu

Rock and Soil Mechanics

Studying the seismic effects of valley site has critical guiding significance for site selection and aseismic design. Based on the analysis of centrifuge shaking table tests, the ground motion response pattern of the trapezoidal valley was studied. The results showed that there was a certain amplification effect of ground motion in the bedrock valley site. The amplification effect varied with the change of terrain, but the amplification effect was not significant. Different site locations had a small influence on the response spectrum. In the bedrock-overburden model, an obvious increase of the ground motion magnification was observed at the bedrock surface. …

Tunnel Face Stability Analysis By The Upper-Bound Finite Element Method With Rigid Translatory Moving Element In Heterogeneous Clay, Feng Yang, Shi-Hua He, Yao-Jie Wu, Li-Yan Ji, Jing-Jing Luo, Jun-Sheng Yang

Rock and Soil Mechanics

The upper-bound finite element method with rigid translatory moving elements (UBFEM-RTME) is further improved to optimise its suitability for analysing the stability in heterogeneous clay. The method is applied to investigate the stability of the tunnel face in undrained clay layer subjected to surface surcharge. The variation of stability load ?s /cu0 and the morphological characteristics and discipline of the effective discontinuities mechanism are obtained for various combinations of dimensionless buried depth ratio C/D, dimensionless gravity parameter ?D/cu0 and the heterogeneous parameter ?D/cu0. The results reveal that C/D and ?D/cu0 have a significant effect on ?s /cu0 and failure mechanism. …

The Numerical Manifold Method For Boundary Integrals In Elastostatics, Zhi-Bao Nie, Hong Zheng, Tao Wan, Shan Lin

Rock and Soil Mechanics

The traditional numerical manifold method (NMM) adopts the form of regional integration. This paper proposed a new NMM in the form of boundary integral by integrating the advantages of both the boundary element method (BEM) and the NMM, namely the dimension reduction of BEM and the flexibility of local base selection of NMM. For two-dimensional elastostatics problems, three different benchmark examples with analytical solutions are applied to verify the validity and efficiency of the newly proposed NMM. The results show that the accuracy of the proposed procedure can be effectively improved by increasing the order of the local basis.

Study And Application Of The Relationship Between Preferential Flow Penetration And Slope Deformation, Xiao-Hu Huang, Wu Yi, Hai-Feng Huang, Yong-Huang Deng

Rock and Soil Mechanics

The cracks on the ground surface will form a complete crack system gradually with the increase of the slope deformation. In view of the rainfall infiltration process of this type of landslide, it is pointed out that the preferential flow penetration developed along the dominant channel formed along the surface crack leads to the deterioration process of landslide stability and promotes the development of deformation. This paper systematically analyzes the relationship between the preferential flow penetration, the fluctuation of groundwater level and the slope deformation. The Wangjiapo landslide is investigate to reveal the temporal-spatial deformation evolution of the dominant channel …

Assessment Of The Performance Of Field-Scale Bioretention Systems To Reduce Phosphorus Loads From Urban Stormwater, Jaeleah J. Goor

Electronic Thesis and Dissertation Repository

High nutrient loading can degrade surface water quality worldwide. Bioretention systems are low impact development stormwater management features designed to remove pollutants, including phosphorus (P), from urban stormwater runoff. In this study, two field-scale bioretention systems installed in London, Ontario, Canada were monitored to develop detailed understanding of P behaviour and the hydro-biogeochemical mechanisms that govern overall P retention. Net retention of total P and dissolved organic P, and net release of soluble reactive P (SRP) and total dissolved P were observed. Prolonged input of road de-icing salts (NaCl) in winter and early spring may result in high P release …

3d-Printed Leg Design And Modification For Improved Support On A Quadruped Robot, Jasmin S. Collins

Undergraduate Research & Mentoring Program

The Agile and Adaptive Robotics Lab aims to uncover the biological and physiological complexities in animal agility and adaptive control, which can be replicated through robotics and provide further applications in biology and medicine. One project within the lab focuses on understanding structure, actuation, and control through the modeling of a canine quadruped robot.

The AARL has developed a full-body quadruped robot with artificial muscles that control limb movement and a body that is built from 3D-printed parts. This specific project involved modification of these existing parts to (a) minimize deflections in the front legs, causing unwanted lateral and abduction/adduction …

A Big Data Lake For Multilevel Streaming Analytics, Ruoran Liu, Haruna Isah, Farhana Zulkernine

Publications and Scholarship

Large organizations are seeking to create new architectures and scalable platforms to effectively handle data management challenges due to the explosive nature of data rarely seen in the past. These data management challenges are largely posed by the availability of streaming data at high velocity from various sources in multiple formats. The changes in data paradigm have led to the emergence of new data analytics and management architecture. This paper focuses on storing high volume, velocity and variety data in the raw formats in a data storage architecture called a data lake. First, we present our study on the limitations …

Towards Distributed Recycling With Additive Manufacturing Of Pet Flake Feedstocks, Helen A. Little, Nagendra Gautam Tanikella, Matthew J. Reich, Matthew J. Fiedler, Samantha L. Snabes, Joshua M. Pearce

Michigan Tech Publications

This study explores the potential to reach a circular economy for post-consumer Recycled Polyethylene Terephthalate (rPET) packaging and bottles by using it as a Distributed Recycling for Additive Manufacturing (DRAM) feedstock. Specifically, for the first time, rPET water bottle flake is processed using only an open source toolchain with Fused Particle Fabrication (FPF) or Fused Granular Fabrication (FGF) processing rather than first converting it to filament. In this study, first the impact of granulation, sifting, and heating (and their sequential combination) is quantified on the shape and size distribution of the rPET flakes. Then 3D printing tests were performed on …

Evaluation Of Impact Of Fiber Type And Dosage Rate On Volumetrics And Laboratory Performance Of Asphalt Mixtures, Ahmad G. M. Alfalah

Theses and Dissertations

The purpose of this study is to evaluate the impact of fiber types, binder content, and dosage rates on the volumetric properties and laboratory performance of asphalt mixtures. One asphalt mixture (control) and four fiber types (Fiberglass, Basalt, Carbon, and Polyolefin/Aramid) were used to evaluate the impact of fiber types and dosage rates. Two mixing procedures for introducing fibers into asphalt mixtures were also evaluated: dry and proportional dispersion methods. To evaluate the impact of fiber types, 0.16% by total mix weight was used. Rutting, cracking, and durability performance tests were evaluated. Furthermore, using 0.15% and 0.3% fiber dosage rates, …

Elementary Teachers’ Mental Images Of Engineers At Work, Rebekah Hammack, Juliana Utley, Toni Ivey, Karen High

Journal of Pre-College Engineering Education Research (J-PEER)

The purpose of the current study was to determine the impacts of a multiple-day engineering-focused professional development program on elementary teachers’ perceptions of the work of engineers and their use of mathematics and science. Data were collected in the form of drawings of engineers prior to and immediately after the professional development program as well as an open-ended exit survey at the end of the program. Participants’ drawings were scored in the following areas: use of mathematics, use of science, and work of an engineer. Wilcoxon signed-rank tests revealed that the only significant change between measures was in ‘‘work of …

Additively Manufactured Parametric Universal Clip-System: An Open Source Approach For Aiding Personal Exposure Easurement In The Breathing Zone, Kirsi Kukko, Jan Sher Akmal, Anneli Kangas, Mika Salmi, Roy Björkstrand, Anna-Kaisa Viitanen, Jouni Partanen, Joshua M. Pearce

Michigan Tech Publications

Design for additive manufacturing is adopted to help solve problems inherent to attaching active personal sampler systems to workers for monitoring their breathing zone. A novel and parametric 3D printable clip system was designed with an open source Computer-aided design (CAD) system and was additively manufactured. The concept was first tested with a simple clip design, and when it was found to be functional, the ability of the innovative and open source design to be extended to other applications was demonstrated by designing another tooling system. The clip system was tested for mechanical stress test to establish a minimum lifetime …

Global Convergence Of Covid-19 Basic Reproduction Number And Estimation From Early-Time Sir Dynamics, Gabriel G. Katul, Asaad Mrad, Sara Bonetti, Gabriele Manolia, Anthony J. Parolari

Civil and Environmental Engineering Faculty Research and Publications

The SIR (‘susceptible-infectious-recovered’) formulation is used to uncover the generic spread mechanisms observed by COVID-19 dynamics globally, especially in the early phases of infectious spread. During this early period, potential controls were not effectively put in place or enforced in many countries. Hence, the early phases of COVID-19 spread in countries where controls were weak offer a unique perspective on the ensemble-behavior of COVID-19 basic reproduction number inferred from SIR formulation. The work here shows that there is global convergence (i.e., across many nations) to an uncontrolled R_o=4.5 that describes the early time spread of COVID-19. This value …

The Effect Of Free-Stream Turbulence On Turbulent Boundary Layers And Convective Heat Transfer From Flat Plates, Ivian Carolina Alfaia De Magalhaes

Electronic Thesis and Dissertation Repository

The present work investigates the effect of free-stream turbulence (FST) on turbulent boundary layers and forced convective heat transfer from flat plates. High resolution, 2-D and 3-D, steady Reynolds-Averaged Navier-Stokes (RANS) simulations using Computational Fluid Dynamics (CFD) techniques were performed to analyze the influence of different free-stream conditions, such as turbulence intensity (TI), integral length scale (L_u) and free-stream velocity (U_o) on local and total skin friction and convective heat transfer coefficients (CHTC), as well as on turbulent boundary layer parameters (boundary layer thickness and momentum thickness). The present study shows that …

The Importance Of Collaborative Design For Narrowing The Gender Gap In Engineering: An Analysis Of Engineering Identity Development In Elementary Students, Mandy Mclean, Jasmine M. Nation, Alexis Spina, Tyler Susko, Danielle Harlow, Julie Bianchini

Journal of Pre-College Engineering Education Research (J-PEER)

Research suggests that, to narrow the gender gap in engineering, we should focus on helping young girls identify with engineering both because gendered attitudes emerge around kindergarten and because identity is more predictive than performance on persistence in the field. This qualitative study sought to understand the impact of collaborative engineering design on the development of engineering identities in elementary-school students and compared the findings across gender. We focused on three tiers of collaboration embedded into the engineering design process: peer groups, role models, and shared goals. More specifically, the elementary students worked in small teams and partnered with undergraduate …

Jump Linear Quadratic Control For Microgrids With Commercial Loads, Maryam Khanbaghi, Aleksandar Zečević

Electrical and Computer Engineering

Due to the aging power-grid infrastructure and increased usage of renewable energies, microgrids (μGrids) have emerged as a promising paradigm. It is reasonable to expect that they will become one of the fundamental building blocks of a smart grid, since effective energy transfer and coordination of μGrids could help maintain the stability and reliability of the regional large-scale power-grid. From the control perspective, one of the key objectives of μGrids is load management using local generation and storage for optimized performance. Accomplishing this task can be challenging, however, particularly in situations where local generation is unpredictable both in quality and …

Research On Direct Shear Behaviour And Fracture Patterns Of 3d-Printed Complex Jointed Rock Models, Pei-Tao Wang, Zheng-Jun Huang, Fen-Hua Ren, Liang Zhang, Mei-Feng Cai

Rock and Soil Mechanics

Geometry and mechanical characteristics of joints are key factors affecting the shear behaviors and fracture patterns of jointed rock mass. Using 3D printing technique, experimental jointed rock specimens containing rough joints with varied joint roughness coefficient (JRC), different types of geometrical joints, and fractrues network were established respectively. Then direct shear tests were conducted on the jointed rock models to study the shear strength and failure patterns. The results show that the values of shear strength of jointed rock models fluctuate greatly with varied JRC curves. The peak shear displacement decreases with increasing amplitude of fluctuation. The lowest and highest …

Circular Sliding Solution Of Mining Stability And Failure Depth Of Floor Layered Structure On Coal Face, Hai-Feng Lu, Xiang-Shuai Meng, Wei Yan, Duo-Xi Yao

Rock and Soil Mechanics

At present the theoretical calculation of the stope floor failure depth simplifies the floor as elastomer or plastomer for analysis. However, the application conditions for the two methods are not specified. Meanwhile, this calculation approach cannot reflect the layered structure of the stope floor. Therefore, the limit equilibrium failure mode of the floor under abutment pressure is regarded as a circular-arc sliding. The Swedish slice method is used to search for dangerous sliding surfaces and to obtain the stability coefficient as well as the maximum depth of the sliding surface. Based on the safety factor value given by the foundation …

Study On Breakage Behaviour Of Original Rockfill Materials Considering Size Effect On Particle Strength, Feng Wang, Jian-Qing Zhang

Rock and Soil Mechanics

In high rockfill dam, particle breakage is one of the main factors that lead to dam deformation. However, because of the large size of the rockfill particles, the breakage degree of the prototype rockfill materials is difficult to be measured directly through laboratory test. Therefore, the common practice is to reduce the size of the prototype gradation particle to less than 60 mm before the laboratory test can be carried out. However, due to the significant difference between the prototype and the test gradation, the parameters measured in the test are often quite different from the actual parameters of the …

Preliminary Study On Real-Time Pore Water Pressure Response And Reinforcement Mechanism Of Air-Booster Vacuum Preloading Treated Dredged Slurry, Li Shi, Dong-Dong Hu, Yuan-Qiang Cai, Xiao-Dong Pan, Hong-Lei Sun

Rock and Soil Mechanics

Laboratory tests have been carried out for simulating dredged-slurry treatment combining air-booster and conventional vacuum preloading methods. Settlement plate, micro pore water pressure transducer and miniature vane shearing instrument are adopted for monitoring the settlement, the pore pressure dissipation and the soil strength during the test. The tests results demonstrate that the air-booster vacuum-preloading method can significantly improve the soil strength, pore-water pressure dissipation and settlement. In particular, the real-time responses of pore-water pressure during the air-pressurizing process have been obtained that, in combination with the numerical simulations, help derive the reinforcement mechanism of the air-booster vacuum preloading method, which …

Experimental Study On Shear-Seepage Behaviour Of Rock Joints Under Constant Normal Stiffness, Cai-Chu Xia, Qiang-Feng Yu, Xin Qian, Yang Gui, Xiao-Qing Zhuang

Rock and Soil Mechanics

In order to study the shear-flow coupling characteristics of joints under constant normal stiffness (CNS) boundary condition, the shear-flow coupling tests under three different stiffness and seepage pressure settings were carried out for duplicate joint specimens with three different joint roughnesses. Meanwhile, the effects of normal stiffness, seepage pressure and joint roughness on the mechanical properties and seepage characteristics in joint shearing process were systematically analyzed. The test results indicate that the peak shear strength of joint increases with the increasing of normal stiffness, while the flow rate, equivalent hydraulic aperture and transmissivity decrease with the increasing of normal stiffness; …

Evolution And Mechanism Of Permeability Of Unconsolidated Sandstone Under High Hydrostatic Pressure Compaction, Fu-Jian Yang, Da-Wei Hu, Zhen-Bao Tian, Hui Zhou, Jing-Jing Lu, Yu-Jie Luo, Shu-Qiang Gui

Rock and Soil Mechanics

The unconsolidated sandstone in hydrothermal geothermal field in Jianghan basin is taken as the research object. The hydrostatic pressure is applied to a geostress equal to 12.5 MPa. After the deformation of sample is stabilised, the evolution and mechanism of the permeability of unconsolidated sandstone under the compaction of high hydrostatic pressure are studied, which can provide some suggestions for the selection of equipment operating parameters for the tailwater recharge process in the hydrothermal geothermal field. The results indicate that under high hydrostatic pressure compaction, the permeability of unconsolidated sandstone samples tends to be a constant valued of 4.0×10?3 ?m2 …