Civil and Environmental Engineering Commons^™

Research On The Mechanical Characteristics Of Granite Failure Process Under True Triaxial Stress Path, Jie Liu, Li-Ming Zhang, Yu Cong, Zai-Quan Wang

Rock and Soil Mechanics

No abstract provided.

Long-Term Creep Law And Constitutive Model Of Extremely Soft Coal Rock Subjected To Single-Stage Load, Xing-Kai Wang, Cai-Chu Xia, Zhe-Ming Zhu, Wen-Bing Xie, Lei-Bo Song, Guan-Sheng Han

Rock and Soil Mechanics

No abstract provided.

Influencing Factors And Mechanism Analysis Of Strength Development Of Geopolymer Stabilized Sludge, Heng-Yu Zhou, Xiu-Shan Wang, Xing-Xing Hu, Zhi-Qi Xiong, Xiao-Yuan Zhang

Rock and Soil Mechanics

No abstract provided.

Experimental Study On The Stress Wave Attenuation Effect Of Filled Cracks In Rocks Under Confining Pressure, Xin Liu, Hong-Fa Xu, Peng-Xian Fan, Han-Sheng Geng, Jia-Quan Mo, De-Rong Wang

Rock and Soil Mechanics

To study the effectiveness of filled cracks as a means of anti-blasting and wave-elimination for underground protective structures, 36 one-dimensional impact tests were carried out on the intact rock specimens and rock specimens with filled cracks using the SHPB apparatus. The transmittance, stress wave velocity and peak stress value of the specimen under different working conditions were obtained. The impacts of confining pressure level, filling thickness and filling material types on stress wave attenuation were analyzed. The results show that, with the increase of the thickness of the filled cracks, the transmittance of the specimen, stress wave velocity, and stress …

Experimental Study On The Evolution Characteristics Of Cyclic Frost Heaving Pressure Of Saturated Fractured Granite, Chen Qiao, Yu Wang, Zheng-Yang Song, Chang-Hong Li, Zhi-Qiang Hou

Rock and Soil Mechanics

The frost heaving pressure generated by water–ice phase change and volume expansion of saturated fractured rock mass in cold regions promote the initiation and expansion of new fractures, and lead to further damage and deterioration of fractured rock mass. To reveal the frost heaving pressure degradation mechanism of fractured rock mass subjected to multiple freeze–thaw cycles, the repeated frost heaving pressure monitoring test was carried out on saturated fractured granite with different macroscopic fractures under different freezing temperatures. The evolution characteristics of cyclic frost heaving pressure and the effect of crack size, freezing temperature and the number of freeze–thaw cycle …

Numerical Simulation Of Grouting Process In Rock Mass With Rough Fracture Network Based On Corrected Cubic Law, Wei Cui, Li-Xin Wang, Zhi-An Jiang, Chao Wang, Xiao-Hua Wang, She-Rong Zhang

Rock and Soil Mechanics

Due to the influence of fracture undulation, there is an obvious difference in the grout flow rule between the rock mass with rough fractures and the rock mass with existing results. Based on the parallel plate model of fluid flow in a single crack, a flow rule model of viscous fluid in a rough fracture was developed using a corrected cubic law. The derived results were agreed well with that from a single crack grouting test. Based on a discrete fracture network (DFN) model, the grouting process in a fractured rock mass was simulated and studied by changing the fracture …

Compression Test And Numerical Simulation Research On Improved Red Beds Subgrade Fillers In Sichuan–Tibet Railway, Hua Xu, Ting-Yu Zhou, Xin-Yu Wang, Jie Zhang, Xiao-Bo Zhang, Yu-Chen Liu

Rock and Soil Mechanics

No abstract provided.

Experimental Study On The Strength Characteristics Of A Transparent Cemented Soil, Xian-Lun Leng, Chuan Wang, Rong Pang, Qian Sheng

Rock and Soil Mechanics

The visual physical model testing technology based on transparent soils is playing an increasingly important role in the study of deformation and failure mechanism in geotechnical engineering. The preparation of transparent soils with high transparency, stable physical and mechanical properties, and suitable for simulating different natural rocks and soils is the basis for the development of this technology. Given the lack of transparent materials for clays and soft rocks, a transparent cemented soil has been formulated. The transparent cemented soil is synthesis using fused quartz as the skeleton particles, nano-level hydrophobic fumed silica powder as the cement and mixed mineral …

Study On Prestress Long-Term Loss Of Anchor Cable Considering Coupled Multiple Factors, Zhong-Ju Feng, Guan Jiang, Rui-Xin Zhao, Hou-Sheng Long, Zheng-Bin Wang, Zheng-Xu Zhang

Rock and Soil Mechanics

In order to study the long-term loss law of anchorage force and the calculation method of prestress loss of anchorage force, a calculation method of the prestress loss of anchorage force was proposed to account for three factors. The proposed method is based on the generalized Hooke’s law, relaxation rate time-history response equation and improved coupling constitutive model. It was adopted to calculate the theoretical loss value of the anchor cable prestress coupled with the internal sliding lock of the anchor plate, the stress relaxation of the cable body steel strand, and the rock mass creep, respectively. In order to …

Analysis Of Stress-Structural Collapse Mechanism Of Columnar Jointed Basalt Under High Stress, Jian-Cong Zhang, Quan Jiang, Xian-Jie Hao, Guang-Liang Feng, Shao-Jun Li, Zhi-Lin Wang, Qi-Xiang Fan

Rock and Soil Mechanics

Columnar jointed rock mass with unique joint network structure is a special type of jointed rock mass, which is a binary structure composed of high strength ‘basalt block’ and specific ‘dominant joint’. Relaxation, opening and slippage of columnar jointed surfaces and disintegration of columns occur easily during excavation under high ground stress, which eventually lead to disastrous collapses in columnar jointed rock mass. The construction safety of underground engineering under high stress is severed restricted by it. By combining acoustic wave, borehole camera and other integrated in-situ testing technology and numerical simulation, the mechanism of stress-structural collapse in columnar jointed …

Lunar Regolith Simulant Behaviours Affected By Shock Metamorphism And Mineralogy, Xiao Chen Zhang

Electronic Thesis and Dissertation Repository

There are still many gaps in improving the fidelity of lunar regolith simulants to simulate more properties. This study compares some fundamental physical and mineralogical properties of three types of lunar highland regolith simulants: LHS-1, a commercial product with high mineralogical fidelity; UWO-1G, an original simulant that is the main component of LHS-1; and UWO-1S, another original product that is attempted to produce shocked grains in lunar simulants from pulverizing and mixing impact rocks sourced from the Mistastin Crater.

Preliminary results indicated that even though all simulants are composed of mostly plagioclase minerals and have similar particle size distribution patterns, …

Seismic Response Of Driven And Helical Piles In Non-Liquefiable And Liquefiable Soils, Ahmed Fouad Hussein

Electronic Thesis and Dissertation Repository

The thesis investigates the nonlinear soil-pile-structure interaction through three-dimensional nonlinear finite element models (FEM) employing the OpenSees platform. The FEMs were validated with the results of large-scale shaking table tests of model pile groups-superstructure systems in dry and saturated sand and large-scale field tests on single piles installed in cohesive soil. The numerical models correctly predicted the different pile deformation modes that were exhibited in the experiments. The results illustrated that the inertial interaction contributed to the bending moments at the pile top, while the kinematic interaction contributed to the bending moment at the layers interface. In addition, the excess …

Analysis Of Catastrophic Instability Of Roof-Rib Pillar Support System Under Backfill Mining, Xuan-Ting Liu, Cong-Xin Chen, Xiu-Min Liu, Kai-Zong Xia, Chu-Qiang Zhang, Tian-Long Wang, Yue Wang

Rock and Soil Mechanics

A roof?rib pillar support system is often formed in the metal mines that applied to the backfill mining method. In order to ensure the safe mining, it is of great significance to explore the failure mechanism of the roof?rib pillar support system under backfill mining. On the basis of considering the side pressure effect of the backfill on the rib pillar, a mechanical model of the roof?rib pillar support system under backfill mining was established. Furthermore, the catastrophe theory was used to explore the failure mechanism of the supporting system under the action of the filling body, and the influence …

Development Of Pressure−Suction Element Model For Film Water In Freezing Soil And Experimental Verification, Han-Qing Chen, Hua Cheng, Guang-Yong Cao, Hai-Bing Cai, Chuan-Xin Rong, Zhi-Shu Yao

Rock and Soil Mechanics

To unify the source power of water migration, a pressure-suction element model of film water is constructed on the basis of the film water hydraulic driving force model and the surface adsorption force model. Model analysis shows that under the dual action of net suction and actual liquid pressure (or theoretical suction and actual ice pressure), the surface adsorption force can be generated, which drives the tangential migration of water along the surface of the substrate. In view of the fact that the surface adsorption force has nothing to do with the boundary conditions, it is suitable for any form …

Experimental Study Of Dispersive Clay Modified By Calcium Lignosulfonate, Sheng-Ge Ji, Bao-Zhong Wang, Xiu-Juan Yang, Heng-Hui Fan

Rock and Soil Mechanics

Dispersive clay is a type of water-sensitive soil, which has the characteristics of dispersivity and material loss when encountering water. The influential factors and modification mechanism of dispersive clay modified by calcium lignosulfonate (CL) were studied using dispersivity test, mechanical property test, chemical property test, microstructure test and simulated rainfall scouring test. The test results indicated that with the increase in CL content, the dispersivity, slake durability and erosion resistance of the modified soil were gradually improved, and it had a good modification effect when the CL content reached 3.0%. The unconfined compressive strength (UCS) first increased and then decreased, …

Analytical Solution Of Additional Response Of Shield Tunnel Under Asymmetric Jack Thrust, Zu-Xian Wang, Cheng-Hua Shi, Jian-Wen Liu

Rock and Soil Mechanics

When shield is driving along a curve alignment or during deviation correction, the asymmetrical thrust will generate an additional bending moment at the head of the tunnel, which will cause construction problems such as longitudinal deformation of the tunnel and dislocation between rings. Based on the theory of elastic foundation beam, the shield tunnel is simplified as a Timoshenko beam in Winkler foundation, an analytical model for evaluating the additional response of the shield tunnel induced the asymmetric thrust is established, and the analytical solutions of longitudinal deformation and internal force of shield tunnel are deduced. Then the correctness and …

Numerical Analysis Of Seismic Damage Characteristics Of An Underground Cavern Intersected By A Steeply Dipped Fault, Shi-Jie Chen, Ming Xiao, Xiao-Wei Wang, Jun-Tao Chen

Rock and Soil Mechanics

The steeply dipped fault zone is the weak link of the seismic stability of underground caverns. Aimed at the complex dynamic interaction characteristics between the surrounding rock and fault, based on the Ladanyi's shear strength model, the seismic deterioration coefficient was introduced, and a shear strength model considering nonlinear mechanical properties and seismic deterioration effect was established. Further considering the discontinuous deformation characteristics between surrounding rock and faults, a three-dimensional dynamic contact force method was proposed considering both the complex shear strength and multiple contact states. The method was applied to the Jinchuan underground powerhouse to study its seismic damage …

Investigation Of Damage Evolution And Its Model Of Rock-Like Brittle Materials, Chao Zhang, Chu-Qing Yang, Yun Bai

Rock and Soil Mechanics

To investigate the description and evolution of the damage state of rock-like brittle materials, the physical meaning of each elastic modulus method parameter based on the strain equivalence hypothesis and the limitations of the model application are discussed. The modulus change during the triaxial cyclic loading and unloading test of limestone is studied. Moreover, the defects of the unloading modulus substitution method and the statistical damage evolution model in damage evolution analysis are discussed. The results show the existing elastic modulus method can only be used to reflect the damage evolution process of rock under uniaxial compression, and the unloading …

Prediction Of Unsaturated Permeability Curve Of Compaction Loess With Pore-Size Distribution Curve And Its Application Scope, Yan Li, Tong-Lu Li, Xiao-Kun Hou, Hua Li, Jie Zhang

Rock and Soil Mechanics

The unsaturated permeability curve is governed by the pore-size distribution curve, which can be used to predict the permeability curve. In order to investigate the applicability of this method for compacted loess, three groups of compacted loess samples with different dry densities were prepared. The pore-size distribution (PSD) curves of soil samples were measured using mercury injection porosimeter test. The unsaturated permeability curves of soil samples were measured by small soil column equipment designed by our research group. Then the PSD curves were used to predict the permeability curves and compared with the measured data from soil column test. The …

Modeling Unimodal/Bimodal Soil-Water Retention Curves Considering The Influence Of Void Ratio Under Capillarity And Adsorption, Zhi-Qiang Lin, Jian-Gu Qian, Zhen-Hao Shi

Rock and Soil Mechanics

The constitutive relationship between suction and degree of saturation is of great significance for estimating the shear strength and deformation behavior of unsaturated soils. A unimodal/bimodal soil-water retention curve (SWRC) is proposed considering the effects of various pore structures and the effects of void ratio on capillarity and adsorption. The different mechanisms of water retention through capillarity and adsorption are explicitly distinguished in the proposed model. The relationship between the capillary degree of saturation and suction is described as a specific function related to the characteristics of pore-size distribution, while the adsorptive degree of saturation is modeled considering the effect …

Static Liquefaction Of Oil Sand Tailings: An Experimental Investigation Into The Effect Of Saturation And Fines Content, Farshad Zehforoosh

Electronic Thesis and Dissertation Repository

The main goals of this research are to explore the influence of partial saturation and fine content on the shear response of oil sand tailings, to identify the liquefaction susceptibility under different initial states. Monotonic triaxial compression tests were carried out to understand the mechanical behavior of the saturated oil sand tailings with varying void ratios. Then the effect of fine content on the yield and critical shear strength, critical state line, and instability line was evaluated by increasing the fine content up to 50%. The experimental results revealed that the shear strength of the oil sand increases with fine …

Towards Modeling Projectile Penetration In Dry And Multiphase Granular Materials, Mohmad Mohsin Thakur

Doctoral Dissertations

The present work aims at developing and validating numerical modeling strategies in granular materials impacted by a projectile. The focus is on two regions: (a) near-field: region near the tip and along the path of a projectile where comminution of grains is significant, (b) intermediate-field: region far from the projectile where grain-scale interactions are important but stresses are not high enough to cause crushing of the grains.

A novel framework has been introduced and validated wherein particle shape captured using X-ray CT imaging was incorporated in FEM simulations using shell elements for simulating triaxial boundary value problems. The results indicate …

Additive Manufacturing Of Soil Using Bio-Cementation, Christina Childress

Graduate Theses and Dissertations

Microbially Induced Calcite Precipitation (MICP) is an emerging soil treatment technique that is proven to increase strength, decrease erosion, reduce liquefaction risk, enhance slope stability, decrease compressibility, decrease swelling potential, and overall create a more competent soil. The benefits and applications of MICP are broad, and this research seeks to broaden them further by developing a single-phase additive manufacturing application with no treatment time delay. This is done by analyzing layering behaviors of five USCS soil classifications (100 % Ottawa sand, sand clay mixtures, and 100% lean clay) which provides insight into process variables such as the solution volume and …

Measuring Foundation Course Modulus Using Falling Weight Deflectometer, Light Weight Deflectometer, And Dynamic Cone Penetration, Bruce Barrett, Kellie Troxel, Brady Dresselhaus, David Hansen

Nebraska Department of Transportation: Research Reports

The purpose of this investigation was to determine the feasibility of measuring bituminous foundation course modulus under concrete roadways by comparing testing results derived before and after paving using FWD, Light Weight Deflectometer (LWD), and Dynamic Cone Penetrometer (DCP). The foundation course modulus was determined using FWD data and Darwin design software (‘93 AASHTO). Results from Phase I data collection, which occurred prior to pavement placement, provided a baseline for comparison. The maximum modulus was 398,000 PSI and the minimum was 85,000 PSI, yielding a range of 315,000 PSI and an average modulus of 123,000 PSI over the length of …

Identification Of Phosphorous Loading Point Source Facilities To 303(D) Listed Nutrient Impaired Waters Through Watershed Delineation Using Arcgis For Life Cycle Assessment Applications, John Zimmerman

Chemical Engineering Undergraduate Honors Theses

The work done for this project is part of a larger “life cycle assessment (LCA) of novel electrochemical phosphorus recovery technology at the wastewater treatment plant and U.S. watershed scales” (Morrissey 2019). The goal of that LCA is to determine “environmental impacts of implementing electrochemical struvite recovery at the wastewater treatment plant, U.S watershed, and global scales” (Morrissey 2019). This project’s goal is to identify locations deemed more sensitive to eutrophication impacts. The results will be used as part of the life cycle inventory (LCI) accounting for geographically explicit phosphorus flows. The waters identified as impaired were sourced from the …

Guidelines For Designing The Overhead Transmission Tower Foundations Adjacent To Cohesionless Slopes, Meshel Q. Alkahtani

Electronic Thesis and Dissertation Repository

Foundations supporting electrical transmission line towers are subjected to oblique loading due to tower own weight along with wind loading. Due to land limitation and linear alignment of transmission lines, many power transmission towers are situated in sand near sloping grounds and proper evaluation of their foundation performance is essential for the safety and reliability of the critical power transmission lines. There is currently no guidance available on the behaviour of transmission towers foundations constructed near slopes. Thus, the primary objectives of this study are to evaluate the response of transmission tower foundations in cohesionless sloping grounds and investigate the …

General Analytical Solution For Consolidation Of Sand-Drained Ground Considering The Vacuum Loading Process And The Time-Dependent Surcharge Loading, Wei-An Lin, Wen-Hao Jiang, Liang-Tong Zhan

Rock and Soil Mechanics

Based on Barron’s equal strain consolidation theory, the consolidation governing equation of sand-drained ground under vacuum combined surcharge preloading is derived, and a general analytical solution is obtained, which considers the vacuum loading process, the time-dependent surcharge loading, the characteristics of the vacuum pressure decreasing along with the depth and radial direction, and the smear effect of vertical drains and the vertical flow. The correctness of the analytical solution proposed in this paper is verified by comparing the degenerate analytical solution with the existing analytical solution and the finite difference solution. Based on the analytical solution, the consolidation behaviors of …

Macro And Micro Coupling Analysis Of Cone Penetration Test: Methodology And Application, Chang-Hong Wang, Dao-Fei Tang, Kun Wang, Zhao-Xin Wu

Rock and Soil Mechanics

No abstract provided.

A Constitutive Model Considering Post-Liquefaction Deformation Based On The Logarithmic Skeleton Curve, Qing Dong, Zheng-Hua Zhou, Jie Su, Xiao-Jun Li, Bing Hao

Rock and Soil Mechanics

Most of the constitutive model for liquefaction analysis cannot simulate the large post-liquefaction deformation of saturated sand, and there is little research on the nonlinear time-domain large deformation constitutive relationships suitable for seismic response analysis of saturated sand sites. In this paper, a feasible, simple and applicable large deformation constitutive model for time domain analysis is proposed through experimental analysis and theoretical research. The post-liquefaction stress-strain relationships of liquefied sand are obtained based on the undrained cyclic triaxial test data, then loading-reloading rules of large post-liquefaction deformation are proposed. Combined with the effective stress constitutive model based on logarithmic skeleton …

Effects Of Cyclic Loading Directions On Liquefaction Characteristics Of Saturated Coral Sand, Kang Liu, Guo-Xing Chen, Qi Wu, Wei-Jia Ma, You Qin

Rock and Soil Mechanics

The large scale construction of both military and civil infrastructures located in Nansha reefs and offshore marine areas, South China Sea, has raised the seismic safety a challenging issue for the projects in the region. The influences of fines content (FC) on the liquefaction characteristics of saturated terrestrial quartz sands have been extensively studied, but the corresponding research on saturated coral sands in reclaimed coral islands is less involved. Using the GDS hollow cylinder torsion shear apparatus, a series of isotropically consolidated undrained cyclic tests have been performed on saturated coral sand sampled from the Nansha Islands, South China Sea. …