scholarly journals Water Softening Mechanism and Strength Model for Saturated Carbonaceous Mudstone in Panzhihua Airport, China

2020 ◽  
Vol 2020 ◽  
pp. 1-12
Author(s):  
Ziwen Wang ◽  
Jifang Du ◽  
Shuaifeng Wu ◽  
Yingqi Wei ◽  
Jianzhang Xiao ◽  
...  
Keyword(s):  
Shear Strength ◽  
Water Saturation ◽  
Structural Characteristics ◽  
Water Immersion ◽  
Analytical Techniques ◽  
Friction Angle ◽  
Mechanical Tests ◽  
Water Softening ◽  
Softening Mechanism ◽  
The Stability

To identify the water softening mechanisms that caused landslides in Panzhihua Airport, China, property and saturation tests of the mudstones extracted from a representative landslide were proposed. In this paper, water saturation tests were carried out on samples of carbonaceous mudstone collected from the east side of the No. 12 landslide at the airport. A number of different analytical techniques and mechanical tests were used to determine changes in chemical composition, mineral assemblages, and mudstone structural characteristics, including shear strength, after the mudstone had been softened. Three kinds of changes caused by water and three mudstone softening stages are proposed. The results show that the water has a significant influence on the properties of the mudstone, so the stability of the mudstone in the watery period is a big threat to the upper structure. A model for water immersion mudstone strength softening is developed. The model incorporates a permeability coefficient, the hydraulic gradient, and time; the model can be used to determine the mudstone’s shear strength and internal friction angle. This study provides a reference for the study of rock softened by water immersion.

scholarly journals The Influence of Compaction and Water Conditions on Shear Strength and Friction Resistance between Geotextiles and Ash-Slag Mixture

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1086
Author(s):  
Andrzej Gruchot ◽  
Tymoteusz Zydroń ◽  
Agata Michalska
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Saturation ◽  
Friction Angle ◽  
Interaction Coefficient ◽  
Interfacial Friction ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Angle Of Internal Friction ◽  
Friction Resistance

The paper presents the results of tests of the shear strength of the ash–slag mixture taken from the landfill located in Kraków (Poland) and the interfacial friction resistance at the contact between the ash–slag mixture and woven or nonwoven geotextiles. The tests were carried out in a direct shear apparatus on samples with and without water saturation. The samples for testing were formed in the apparatus box at the optimum moisture by compacting them to IS = 0.90 and 1.00. The test results reveal that the shear strength parameters of the ash-slag mixture were large. It was stated the significant influence of the compaction, the growth of which has resulted in an increase in the angle of internal friction (from 7% to 9%) and cohesion (from 60% to 97%). Whereas the saturation of the samples reduced the shear strength parameters (from 4% to 6%, of the internal friction angle and 30% to 43% of cohesion). The values of the interfacial friction resistance at the contact between the ash–slag mixture and the geotextiles were large as well, but slightly smaller than the values of the shear strength parameters of the mixture itself. The compaction caused an increase in the angle of interfacial friction (from 1% to 5%) and adhesion (from 31% to 127%). The water-saturation of the samples caused a change in the angle of interfacial friction (from −6% to 3%) and decline in the adhesion (from 22% to 69%). Values of the interaction coefficient were about 0.8–1.0 and they tended to rise with increasing the normal stress. Higher values of this parameter were obtained in tests with water saturation and for non-woven geotextiles.

scholarly journals Strength Characteristics and Slope Stability of Expansive Soil from Pingdingshan, China

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ju-yun Zhai ◽  
Xiang-yong Cai
Keyword(s):  
Shear Strength ◽  
Slope Stability ◽  
Expansive Soil ◽  
Friction Angle ◽  
Natural Soil ◽  
Soil Slope ◽  
The Finite Element Method ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
The Stability

By analyzing the characteristics of expansive soil from Pingdingshan, China, the shear strength parameters at different water contents, dry densities, and dry-wet cycles of expansive soil are obtained. It is found that, at higher soil-water content, the internal friction angle is 0° and the shallow layer of expansive soil slope will collapse and destroy; this has nothing to do with the height of the slope and the size of the slope. The parameters of soil influenced by atmosphere are the ones which have gone through dry-wet cycles, and the parameters of soil without atmospheric influence are the same as those of natural soil. In the analysis of slope stability, the shear strength parameters of soil can be determined by using the finite element method, and the stability coefficient of the expansive soil slope can be calculated.

Numerical Simulation for Shear Characteristics of Rock-Mass Structural Plane

2013 ◽  
Vol 734-737 ◽  
pp. 574-578
Author(s):  
Bao Yuan Yuan ◽  
Qi Wang ◽  
Hai Feng Lu
Keyword(s):  
Shear Strength ◽  
Normal Stress ◽  
Friction Angle ◽  
Normal Displacement ◽  
Displacement Curve ◽  
Peak Shear Strength ◽  
Structural Plane ◽  
Linear Feature ◽  
Stress And Deformation ◽  
The Stability

The characteristics of structural plane are very important to the stability of rock mass.In this paper,the stress and deformation characteristics of structural plane under direct shear conditions are analyzed based on FLAC3D code.And the influence of structural plane inhomogeneity to shear test was discussed.The results obtained in this paper indicate that, with the increase of normal stress, the shear strength of structural plane is constantly increasing,and the tow of them presents linear feature significantly. The normal displacement and shear displacement increase with the rise of the normal stress too. The peak shear strength increases gradually on the condition of uneven friction angle in the interface. This situation changes smaller when the discrete degree of friction angle is small. The peak shear strength increases significantly when the discrete degree of friction angle is big,and the stress-displacement curve exhibits a nonlinear characteristics before yield.

Study on the Mechanism of the Landslide of Heda Expressway K377

2011 ◽  
Vol 255-260 ◽  
pp. 3437-3443 ◽  
Author(s):  
Lei Nie ◽  
Min Zhang ◽  
He Qing Jian
Keyword(s):  
Shear Strength ◽  
Stability Analysis ◽  
Structural Characteristics ◽  
Initial Slope ◽  
Economic Losses ◽  
Cut Slope ◽  
Sliding Surface ◽  
Slope Excavation ◽  
Geological Conditions ◽  
The Stability

During the construction of Heda expressway, the Ermi landslide, which occurred on section K377, has interrupted the construction of the expressway. Additional engineering geological investigation became necessary. The direct economic losses are over 3 million US dollars. This paper analyzed the Ermi landslide from the aspects of formation process, engineering geological conditions, the structural characteristics and stability analysis of the landslide. The results show that the formation of the Ermi landslide is mainly due to geological conditions in project area. Because the structure of the sliding body is loose and some weak interlayer exists in the slope, the shear strength of the sliding surface and sliding body is low. As cut-slope excavating, the resistant of the slope body reduced. Eventually the slope lost its stability and a landslide formed. In the stability analysis of the slope, the shear strength parameters of the sliding surface was determined by anti-analysis. Therefore, the result of the evaluation is closer to the actual conditions. Analyzing the stability of the three sliding surfaces respectively, the stability factors for initial slope are between 1.211 and 1.468, and the stability factors for current slope are between 0.958 and 1.076. Hence, the cut-slope excavation is the direct cause of the landslide.

scholarly journals Embankment Displacement PLAXIS Simulation and Microstructural Behavior of Treated-Coal Gangue

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 218 ◽  
Author(s):  
Xiaoyun Yang ◽  
Yan Zhang ◽  
Zhuhan Li
Keyword(s):  
Shear Strength ◽  
Road Construction ◽  
Friction Angle ◽  
Coal Gangue ◽  
Filling Material ◽  
Carbon Structure ◽  
Microscopic Mechanism ◽  
Maximum Displacement ◽  
Microstructural Behavior ◽  
The Stability

The purpose of this study is to investigate the displacement of coal gangue filling material in road construction and microstructural behavior of treated coal gangue by considering the environmental factors of aqueous solutions with different acidity. The displacement analysis of the coal gangue embankment model has been done by means of the finite element method PLAXIS. Furthermore, using the scanning electron microscope, the energy dispersive system, and the Raman spectrometer to analyze the microscopic mechanism in the view of microstructure, elements, the integrity of carbon structure and the stability of chemical bonds of coal gangue. The results show that the larger displacement of the treated coal gangue subgrade is within 4.0 m below the top of the subgrade, and the maximum displacement value is about 7 mm, which is less than the displacement of untreated coal gangue sample. While the treated A-CG and T-CG grain size, surface area and internal friction angle increase, the unstable carbon structure is destroyed, so its shear strength, compression performance, and consolidation effect are improved. S-CG particles are coated with Na-Si-Al gel, which enhances the density, viscosity and shear strength, thus ensuring the stability of the coal gangue subgrade. The treated coal gangue subgrade slope foot displacement, boundary shear stress and safety factor are all meet the specification requirements.

Potential Slip Surfaces of Slope with Strength Parameters

2011 ◽  
Vol 243-249 ◽  
pp. 3315-3318 ◽  
Author(s):  
Hang Lin ◽  
Ping Cao
Keyword(s):  
Shear Strength ◽  
Numerical Analysis ◽  
Factor Of Safety ◽  
Slip Surface ◽  
Friction Angle ◽  
Shear Strength Parameters ◽  
Strength Parameters ◽  
Slip Surfaces ◽  
Stability Of Slope ◽  
The Stability

The cohesion c and friction angle φ are the main strength parameters influencing the stability of slope. Any of them changes, the factor of safety of slope will change, but it has seldom been considered in the literature how the potential slip surface will change at the same time. In the present paper, the analytical deduction and numerical analysis are done to find out the effect of shear strength parameters c and φ to the distribution of potential slip surface. The study shows that, the potential slip surface is affected by the combination of c and φ, whose function is λ=c/(γhtanφ).

Slope Stability Analysis under the Condition of Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 241-245
Author(s):  
Yang Jin
Keyword(s):  
Finite Element Method ◽  
Shear Strength ◽  
Slope Stability ◽  
Negative Impact ◽  
Strength Reduction ◽  
Soil Slope ◽  
Failure State ◽  
Calculation Results ◽  
The Stability ◽  
Shear Strength Reduction

The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

scholarly journals Chitosan hydrogel/silk fibroin/Mg(OH)2 nanobiocomposite as a novel scaffold with antimicrobial activity and improved mechanical properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Reza Eivazzadeh-Keihan ◽  
Fateme Radinekiyan ◽  
Hooman Aghamirza Moghim Aliabadi ◽  
Sima Sukhtezari ◽  
Behnam Tahmasebi ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Cell Viability ◽  
Silk Fibroin ◽  
Analytical Techniques ◽  
Structural Features ◽  
Mechanical Tests ◽  
Chitosan Hydrogel ◽  
Biological Capacity ◽  
Ft Ir ◽  
Novel Scaffold

AbstractHerein, a novel nanobiocomposite scaffold based on modifying synthesized cross-linked terephthaloyl thiourea-chitosan hydrogel (CTT-CS hydrogel) substrate using the extracted silk fibroin (SF) biopolymer and prepared Mg(OH)2 nanoparticles was designed and synthesized. The biological capacity of this nanobiocomposite scaffold was evaluated by cell viability method, red blood cells hemolytic and anti-biofilm assays. According to the obtained results from 3 and 7 days, the cell viability of CTT-CS/SF/Mg(OH)2 nanobiocomposite scaffold was accompanied by a considerable increment from 62.5 to 89.6% respectively. Furthermore, its low hemolytic effect (4.5%), and as well, the high anti-biofilm activity and prevention of the P. aeruginosa biofilm formation confirmed its promising hemocompatibility and antibacterial activity. Apart from the cell viability, blood biocompatibility, and antibacterial activity of CTT-CS/SF/Mg(OH)2 nanobiocomposite scaffold, its structural features were characterized using spectral and analytical techniques (FT-IR, EDX, FE-SEM and TG). As well as, given the mechanical tests, it was indicated that the addition of SF and Mg(OH)2 nanoparticles to the CTT-CS hydrogel could improve its compressive strength from 65.42 to 649.56 kPa.

scholarly journals 3D sub-nanometer analysis of glucose in an aqueous solution by cryo-atom probe tomography

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
T. M. Schwarz ◽  
C. A. Dietrich ◽  
J. Ott ◽  
E. M. Weikum ◽  
R. Lawitzki ◽  
...  
Keyword(s):  
Atom Probe Tomography ◽  
Density Functional ◽  
Chemical Characterization ◽  
Analytical Techniques ◽  
Atom Probe ◽  
Characterization Methods ◽  
Signal Deconvolution ◽  
The Stability ◽  
Frozen Solutions ◽  
3D Volume

AbstractAtom Probe Tomography (APT) is currently a well-established technique to analyse the composition of solid materials including metals, semiconductors and ceramics with up to near-atomic resolution. Using an aqueous glucose solution, we now extended the technique to frozen solutions. While the mass signals of the common glucose fragments CxHy and CxOyHz overlap with (H2O)nH from water, we achieved stoichiometrically correct values via signal deconvolution. Density functional theory (DFT) calculations were performed to investigate the stability of the detected pyranose fragments. This paper demonstrates APT’s capabilities to achieve sub-nanometre resolution in tracing whole glucose molecules in a frozen solution by using cryogenic workflows. We use a solution of defined concentration to investigate the chemical resolution capabilities as a step toward the measurement of biological molecules. Due to the evaporation of nearly intact glucose molecules, their position within the measured 3D volume of the solution can be determined with sub-nanometre resolution. Our analyses take analytical techniques to a new level, since chemical characterization methods for cryogenically-frozen solutions or biological materials are limited.

scholarly journals Tunnel Back Analysis Based on Differential Evolution Using Stress and Displacement

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Joon-Sang An ◽  
Kyung-Nam Kang ◽  
Ju-Young Choi ◽  
Won-Suh Sung ◽  
Vathna Suy ◽  
...  
Keyword(s):  
Differential Evolution ◽  
Differential Evolution Algorithm ◽  
Back Analysis ◽  
Friction Angle ◽  
Internal Displacement ◽  
Average Error ◽  
Analysis Algorithm ◽  
Evolution Algorithm ◽  
Displacement Based ◽  
The Stability

The stability of tunnels has mainly been evaluated based on displacement. Because displacement due to the excavation process is significant, back analysis of the structure and ground can be performed easily. Recently, the length of a segment-lined tunnel driven by the mechanized tunneling method is increasing. Because the internal displacement of a segment-lined tunnel is trivial, it is difficult to analyze the stability of segment-lined tunnels using the conventional method. This paper proposes a back analysis method using stress and displacement information for a segment-lined tunnel. A differential evolution algorithm was adopted for tunnel back analysis. Back analysis based on the differential evolution algorithm using stress and displacement was established and performed using the finite difference code, FLAC3D, and built-in FISH language. Detailed flowcharts of back analysis based on DEA using both monitored displacement stresses were also suggested. As a preliminary study, the target variables of the back analysis adopted in this study were the elastic modulus, cohesion, and friction angle of the ground. The back analysis based on the monitored displacement is useful when the displacement is significant due to excavation. However, the conventional displacement-based back analysis is unsuitable for a segment-lined tunnel after construction because of its trivial internal displacement since the average error is greater than 32% and the evolutionary calculation is finalized due to the maximum iteration criteria. The average error obtained from the proposed back analysis algorithm using both stress and displacement ranged within approximately 6–8%. This also confirms that the proposed back analysis algorithm is suitable for a segment-lined tunnel.

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