scholarly journals Analysis of Reservoir Seismic Law Based on Three-Dimensional Morphological Characteristics of Joint Surface Related to Listric Fault

2022 ◽  
Vol 9 ◽  
Author(s):  
Guoyong Duan ◽  
Yanhai Wang ◽  
Jianghong Chen ◽  
Jingyu Zhang
Keyword(s):  
Structural Characteristics ◽  
Triaxial Compression ◽  
Morphological Characteristics ◽  
Joint Surface ◽  
Three Gorges Reservoir Area ◽  
Small Scale ◽  
Average Height ◽  
Compression Tests ◽  
Structural Morphology ◽  
Arithmetic Average

Since water storage, earthquakes occurred in Badong County, Hubei Province, accounted for as much as one-third of the strong earthquakes in the Three Gorges Reservoir area. For example, the MS5.1 earthquake occurred in December 2013 near the Gaoqiao fault in Badong County. The earthquake time, magnitude, and location analysis showed that reservoir earthquakes in this area exhibited some characteristics, such as periodicity, migration, and deep extension. Based on the regional stratum lithology and structural characteristics, this paper designed a curved joint on a small scale to simulate the structural morphology of the Gaoqiao fault and carried out triaxial compression tests under different immersion times to analyze the morphological parameters of the joint surface. The results showed that topological parameters such as root mean square height (Sq), arithmetic average height (Sa), reverse load area ratio (Smc), and minimum autocorrelation length (Sal) could effectively characterize the degree of damage and deterioration of curved joints. The test privides a reference for analyzing the evolution law of the seismic characteristics of the reservoir.

Exploring the effects of nanoscale zero-valent iron (nZVI) on the mechanical properties of lead-contaminated clay

2019 ◽  
Vol 56 (10) ◽  
pp. 1395-1405 ◽  
Author(s):  
Yong-Zhan Chen ◽  
Wan-Huan Zhou ◽  
Fuming Liu ◽  
Shuping Yi
Keyword(s):  
Shear Strength ◽  
Triaxial Compression ◽  
Morphological Characteristics ◽  
Friction Angle ◽  
Zero Valent Iron ◽  
Compression Tests ◽  
Shear Tests ◽  
Nanoscale Zero Valent Iron ◽  
Triaxial Compression Tests ◽  
Oedometer Tests

Nanoscale zero-valent iron (nZVI) is a well-known efficient nanomaterial for the immobilization of heavy metals and has been widely applied in the remediation of contaminated groundwater and soils. In this study, a series of field emission scanning electron microscopy (FESEM) analyses, vane shear tests, triaxial compression tests, and oedometer tests was conducted on lead-contaminated clay using four dosages of nZVI treatment (0.2%, 1%, 5%, and 10%). The geotechnical properties, including basic index properties, stiffness, shear strength, and compressibility, were assessed after the reaction procedure. FESEM analysis was performed to explore the potential mechanisms of nZVI treatment in terms of morphological characteristics. It was found that the plasticity index decreased gradually with increasing nZVI dosage. Treating contaminated soil with nZVI caused an increase in the vane shear strength, stiffness, and friction angle. The compression index increased gradually because of the nZVI treatment. Based on the FESEM analysis, a conclusion can be deduced that larger aggregates and conjoined structures resulting from nZVI treatment can lead to the strengthening of lead-contaminated clay.

scholarly journals Small-strain deformation behaviour of a clay at frozen and unfrozen states: A comparative study

2019 ◽  
Vol 92 ◽  
pp. 04001
Author(s):  
Satoshi Nishimura ◽  
Shota Okajima ◽  
Jinyuan Wang ◽  
Bhakta Raj Joshi
Keyword(s):  
Strain Rate ◽  
Axial Strain ◽  
Deformation Behaviour ◽  
Triaxial Compression ◽  
Small Strain ◽  
Small Scale ◽  
High Plasticity ◽  
Compression Tests ◽  
Small Strains ◽  
Displacement Sensors

The small-strain deformation behaviour of frozen high-plasticity clay, and the factors influencing it were investigated through parallel tests at frozen and unfrozen states. The first and second series involved temperature-controlled triaxial compression tests on unfrozen and frozen samples, respectively, with accurate strain measurement with local displacement sensors, fully calibrated for cold environment. The small-strain loading was conducted at different axial strain rates and temperatures. At pre-yield small strains in order of 0.001%, Young's modulus was independent of the strain rate, in a same manner as in unfrozen soils. The strain rate only affected the onset of small-scale yielding and the degradation of stiffness after that. The elastic strain range was greater at lower temperature, but the degree of stress-strain non-linearity seen at small strains remained on the whole similar between frozen and unfrozen states. An interesting feature of the frozen clay's stiffness, also confirmed by third test series adopting bender elements, is that it decreases when the soil is frozen from higher effective stress. A simple model was proposed to explain this feature.

scholarly journals Formation conditions and mechanical properties of aggregates produced in tephra–water–snow flows

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Hirofumi Niiya ◽  
Kenichi Oda ◽  
Daisuke Tsuji ◽  
Hiroaki Katsuragi
Keyword(s):  
Mechanical Properties ◽  
Mixing Time ◽  
Testing Machine ◽  
Small Scale ◽  
Scaling Analysis ◽  
Compression Tests ◽  
Ice Slurry ◽  
Experimental Conditions ◽  
Formation Conditions ◽  
Snow And Ice

Abstract The formation of aggregates consisting of snow, water, and tephra has been reported in small-scale experiments on three-phase flows containing tephra, water, and snow, representing lahars triggered by snowmelt. Such aggregates reduce the mobility of mud flow. However, the formation mechanism of such aggregates under various conditions has not been investigated. To elucidate the formation conditions and mechanical properties of the aggregates, we performed mixing experiments with materials on a rotating table and compression tests on the resulting aggregates with a universal testing machine in a low-temperature room at $$0\,^{\circ }\text {C}$$ 0 ∘ C . From experiments with varying component ratios of the mixture and tephra diameter, the following results were obtained: (i) the aggregate grew rapidly and reached maturity after a mixing time of 5 min; (ii) the mass of aggregates increased with snow concentration, exhibiting an approximately linear relationship; (iii) single aggregates with large mass formed at lower and higher tephra concentrations, whereas multiple aggregates with smaller mass were observed at intermediate concentrations; (iv) the shape of the aggregate satisfied the similarity law for an ellipsoid; (v) the compressive mechanical behavior could be modeled by an empirical nonlinear model. The obtained mechanical properties of the aggregates were independent of the experimental conditions; (vi) scaling analysis based on the Reynolds number and the strength of the aggregates showed that the aggregates cannot form in ice-slurry lahars. Our findings suggest that low-speed lahars containing snow and ice are likely to generate aggregates, but snow and ice in the ice-slurry lahars are dispersed without such aggregates.

A Simple Unconsolidated Undrained Triaxial Compression Test Emulator

2015 ◽  
Vol 771 ◽  
pp. 104-107
Author(s):  
Riska Ekawita ◽  
Hasbullah Nawir ◽  
Suprijadi ◽  
Khairurrijal
Keyword(s):  
Triaxial Compression ◽  
Measurement Data ◽  
Radial Strain ◽  
Compression Tests ◽  
Viscous Effects ◽  
Axial Pressure ◽  
Strain Stress ◽  
The University ◽  
And Storage ◽  
Triaxial Compression Tests

An unconsolidated undrained (UU) test is one type of triaxial compression tests based on the nature of loading and drainage conditions. In order to imitate the UU triaxial compression tests, a UU triaxial emulator with a graphical user interface (GUI) was developed. It has 5 deformation sensors (4 radial deformations and one vertical deformation) and one axial pressure sensor. In addition, other inputs of the emulator are the cell pressure, the height of sample, and the diameter of sample, which are provided by the user. The emulator also facilitates the analysis and storage of measurement data. Deformation data fed to the emulator were obtained from real measurements [H. Nawir, Viscous effects on yielding characteristics of sand in triaxial compression, Dissertation, Civil Eng. Dept., The University of Tokyo, 2002]. Using the measurement data, the stress vs radial strain, stress vs vertical strain, and Mohr-Coulomb circle curves were obtained and displayed by the emulator.

scholarly journals Load Distribution on PET-G 3D Prints of Honeycomb Cellular Structures under Compression Load

Polymers ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 1983
Author(s):  
Olimpia Basurto-Vázquez ◽  
Elvia P. Sánchez-Rodríguez ◽  
Graham J. McShane ◽  
Dora I. Medina
Keyword(s):  
Fused Deposition Modeling ◽  
Structural Characteristics ◽  
Honeycomb Structure ◽  
Cellular Structures ◽  
Displacement Curve ◽  
Compression Tests ◽  
Compression Load ◽  
Fused Deposition ◽  
3D Printed ◽  
Printing Direction

Energy resulting from an impact is manifested through unwanted damage to objects or persons. New materials made of cellular structures have enhanced energy absorption (EA) capabilities. The hexagonal honeycomb is widely known for its space-filling capacity, structural stability, and high EA potential. Additive manufacturing (AM) technologies have been effectively useful in a vast range of applications. The evolution of these technologies has been studied continuously, with a focus on improving the mechanical and structural characteristics of three-dimensional (3D)-printed models to create complex quality parts that satisfy design and mechanical requirements. In this study, 3D honeycomb structures of novel material polyethylene terephthalate glycol (PET-G) were fabricated by the fused deposition modeling (FDM) method with different infill density values (30%, 70%, and 100%) and printing orientations (edge, flat, and upright). The effectiveness for EA of the design and the effect of the process parameters of infill density and layer printing orientation were investigated by performing in-plane compression tests, and the set of parameters that produced superior results for better EA was determined by analyzing the area under the curve and the welding between the filament layers in the printed object via FDM. The results showed that the printing parameters implemented in this study considerably affected the mechanical properties of the 3D-printed PET-G honeycomb structure. The structure with the upright printing direction and 100% infill density exhibited an extension to delamination and fragmentation, thus, a desirable performance with a long plateau region in the load–displacement curve and major absorption of energy.

Strength envelope of granular soil stabilized by multi-axial geogrid in large triaxial tests

2020 ◽  
Vol 57 (3) ◽  
pp. 448-452 ◽  
Author(s):  
A.S. Lees ◽  
J. Clausen
Keyword(s):  
Triaxial Compression ◽  
Triaxial Tests ◽  
Compression Tests ◽  
Failure Envelope ◽  
Element Analysis ◽  
Linear Elastic ◽  
Perfectly Plastic ◽  
Elastic Perfectly Plastic ◽  
Triaxial Compression Tests ◽  
Properties Of Soil

Conventional methods of characterizing the mechanical properties of soil and geogrid separately are not suited to multi-axial stabilizing geogrid that depends critically on the interaction between soil particles and geogrid. This has been overcome by testing the soil and geogrid product together as one composite material in large specimen triaxial compression tests and fitting a nonlinear failure envelope to the peak failure states. As such, the performance of stabilizing, multi-axial geogrid can be characterized in a measurable way. The failure envelope was adopted in a linear elastic – perfectly plastic constitutive model and implemented into finite element analysis, incorporating a linear variation of enhanced strength with distance from the geogrid plane. This was shown to produce reasonably accurate simulations of triaxial compression tests of both stabilized and nonstabilized specimens at all the confining stresses tested with one set of input parameters for the failure envelope and its variation with distance from the geogrid plane.

scholarly journals Small-Scale Plastic Deformation of Nanocrystalline High Entropy Alloy

Entropy ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 889 ◽  
Author(s):  
Sanghita Mridha ◽  
Mageshwari Komarasamy ◽  
Sanjit Bhowmick ◽  
Rajiv Mishra ◽  
Sundeep Mukherjee
Keyword(s):  
Plastic Deformation ◽  
Rate Sensitivity ◽  
Small Scale ◽  
High Entropy Alloy ◽  
Compression Tests ◽  
High Entropy ◽  
Grain Sizes ◽  
Plastic Deformation Behavior ◽  
High Strain Rate Sensitivity ◽  
Widespread Interest

High entropy alloys (HEAs) have attracted widespread interest due to their unique properties at many different length-scales. Here, we report the fabrication of nanocrystalline (NC) Al0.1CoCrFeNi high entropy alloy and subsequent small-scale plastic deformation behavior via nano-pillar compression tests. Exceptional strength was realized for the NC HEA compared to pure Ni of similar grain sizes. Grain boundary mediated deformation mechanisms led to high strain rate sensitivity of flow stress in the nanocrystalline HEA.

scholarly journals Semi-empirical elastic–thermoviscoplastic model for clay

2016 ◽  
Vol 53 (10) ◽  
pp. 1583-1599 ◽  
Author(s):  
David Kurz ◽  
Jitendra Sharma ◽  
Marolo Alfaro ◽  
Jim Graham
Keyword(s):  
Stress Level ◽  
Axial Strain ◽  
Triaxial Compression ◽  
Compression Tests ◽  
One Dimensional ◽  
Load Duration ◽  
Compression Creep ◽  
Overconsolidated Clays ◽  
Semi Empirical ◽  
Triaxial Compression Tests

Clays exhibit creep in compression and shear. In one-dimensional compression, creep is commonly known as “secondary compression” even though it is also a significant component of deformations resulting from shear straining. It reflects viscous behaviour in clays and therefore depends on load duration, stress level, the ratio of shear stress to compression stress, strain rate, and temperature. Research described in the paper partitions strains into elastic (recoverable) and plastic (nonrecoverable) components. The plastic component includes viscous strains defined by a creep rate coefficient ψ that varies with plasticity index and temperature (T), but not with stress level or overconsolidation ratio (OCR). Earlier elastic–viscoplastic (EVP) models have been modified so that ψ = ψ(T) in a new elastic–thermoviscoplastic (ETVP) model. The paper provides a sensitivity analysis of simulated results from undrained (CIŪ) triaxial compression tests for normally consolidated and lightly overconsolidated clays. Axial strain rates range from 0.15%/day to 15%/day, and temperatures from 28 to 100 °C.

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