Experimental study of one-dimensional compression creep in crushed dry coral sand

2020 ◽  
Vol 57 (12) ◽  
pp. 1854-1869
Author(s):  
Jiabo Wang ◽  
Pengxian Fan ◽  
Mingyang Wang ◽  
Lu Dong ◽  
Linjian Ma ◽  
...  
Keyword(s):  
Relative Density ◽  
Deformation Behaviour ◽  
Particle Breakage ◽  
Time Dependent ◽  
Silica Sand ◽  
Lateral Strain ◽  
Test Results ◽  
Compression Tests ◽  
One Dimensional ◽  
Coral Sand

Understanding the time-dependent deformation behaviour of backfill coral sand is important to the long-term stability of engineering facilities built on reefs and reclaimed land. A series of one-dimensional compression tests (with no lateral strain) were carried out on crushed coral sand with a variety of grading and relative densities (50%, 70%, and 90%) sampled from the South China Sea. Axial pressure was applied in stepped loading form: 100, 200, 400, 800, and 1600 kPa. Each level loading was applied for 3 days and then completely unloaded until the deformation was stable, after which the next loading level was applied. The test results indicate: (i) the deformation of coral sand is much larger than silica sand and involves a larger proportion of time-dependent and plastic deformation; (ii) the total deformation of coral sand and proportion of irreversible deformation decreases as the relative density increases; (iii) coral sands of better grading tend to deform less in total and have larger proportions of elastic and time-dependent deformation; and (iv) the grading of coral sand changes during the deformation process due to particle breakage. Based on the test results, the relationships between particle breakage and pressure, relative density, and grading, as well as the grain-scale mechanism of the deformation, are discussed.

Detailed amount of particle breakage in nonuniformly graded sands under one-dimensional compression

2020 ◽  
Vol 57 (8) ◽  
pp. 1239-1246 ◽  
Author(s):  
Yu Peng ◽  
Xuanming Ding ◽  
Yang Xiao ◽  
Xin Deng ◽  
Weiting Deng
Keyword(s):  
Size Range ◽  
Particle Breakage ◽  
Silica Sand ◽  
Relative Mass ◽  
Compression Tests ◽  
Compression Pressure ◽  
One Dimensional ◽  
Coral Sand ◽  
Linear Relationships ◽  
Different Color

The coexistence of broken and unbroken grains in each size range can disturb the assessment of actual amount of particle breakage. In this study, a series of one-dimensional compression tests were carried out on three kinds of coral sands and a silica sand to clarify the detailed amount of particle breakage for nonuniformly graded sands. Before the compression tests, both coral and silica sand assemblies were divided into different grain-size groups and dyed in different colors, then mixed as nonuniformly graded packings. After the compression, grains of different color in each size range were discerned quantitatively by implementing particle images segmentation on images of grains. Results show that the extent of particle breakage was found to be larger than the change in relative mass percentage in most size ranges, and the new “absolute particle breakage” wd for each size range satisfied linear relationships with the logarithmic value of compression pressure. Compared with silica sand, coral sand has weaker abrasion under high pressure due to the strong interlock among grains. New breakage indexes of sand samples, based on detailed particle breakage, are proposed. The detailed particle breakage could be useful for proposing a breakage-dependent constitutive model of crushable granular soils.

Negative creep of soils

2020 ◽  
Vol 57 (1) ◽  
pp. 1-16 ◽  
Author(s):  
Yang-Ping Yao ◽  
Yu-Fei Fang
Keyword(s):  
Three Dimensional ◽  
Yield Function ◽  
Time Dependent ◽  
Flow Rule ◽  
Test Results ◽  
Current Yield ◽  
Compression Tests ◽  
Creep Tests ◽  
Negative Creep ◽  
Over Time

After unloading, the deformation of soils cannot be stable immediately, but continues to expand over time even under constant pressure. In this paper, the expansive deformation over time when effective stress is kept constant is defined as the negative creep, while the compressive creep is described as the positive creep. The division between positive creep and negative creep is named the stable normal compression line (SNCL), on which the stress–strain behaviour of the soil is time-independent. Based on the concept of the SNCL and test results, a new formula for creep is proposed. This formula is simple in form and has less parameters, and both negative creep and positive creep can be well predicted. By incorporating this formula into the current yield function of the unified hardening model, a new time-dependent current yield function is built. Combining the yield function, a flow rule, and transformed stress method, a new three-dimensional time-dependent constitutive model considering both positive and negative creep for clays is derived and presented. The new model is then validated by test results, including multistage loading oedometer tests, triaxial undrained creep tests, and triaxial undrained compression tests at the constant strain rates.

scholarly journals Weathering-induced deformation of crushed weak rocks and its countermeasure

2019 ◽  
Vol 92 ◽  
pp. 09003
Author(s):  
Andius D. Putra ◽  
Masaya Takahashi ◽  
Mamoru Kikumoto
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Compression Stress ◽  
Test Results ◽  
Compression Tests ◽  
Wetting And Drying ◽  
Weak Rocks ◽  
One Dimensional ◽  
Significant Compression ◽  
Hydraulic Process

Geotechnical issues such as differential settlements have been reported usually in embankments made of materials derived from weak rocks such as mudstones, siltstones, and shales. The primary cause of the issue is a gradual weakening due to weathering. Crushed weak rocks tend to turn into smaller particles under repeated wetting and drying processes. This phenomenon is a mechanical-hydraulic process known as “slaking”. The present paper discusses the deformation of crushed weak rocks due to slaking and its countermeasure. We performed a series of one-dimensional slaking tests on several weak rocks. We first performed one-dimensional compression tests on dried samples, and applied wetting and drying cycles to the samples while keeping the compression stress constant. The test results revealed that particle size distribution of the samples was broadened due to cyclic wetting and drying processes and that significant compression was exhibited. Moreover, we explored possible countermeasures for reducing the slaking-induced deformation and revealed that compacting the soil to a denser state is the most effective way in reducing the slaking-induced deformation of the crushed mudstone.

The use of one-dimensional compression tests and elastic theory in predicting deformations of rockfill embankments

1976 ◽  
Vol 13 (3) ◽  
pp. 189-200 ◽  
Author(s):  
J. A. Charles
Keyword(s):  
Laboratory Investigation ◽  
Deformation Behaviour ◽  
Elastic Theory ◽  
Compression Tests ◽  
Elastic Parameters ◽  
One Dimensional ◽  
Rockfill Material ◽  
Stress Ratios

A laboratory investigation into the deformation behaviour of a rockfill material undergoing anisotropic compression at different stress ratios is described. The extent to which elastic parameters derived from one-dimensional compression can predict the behaviour of the rockfill at other stress ratios is considered. Stress paths encountered in embankments of cohesionless fill are examined and the relevance of elastic parameters derived from one-dimensional compression tests in analysing the deformations of such embankments is assessed.

Sands subjected to repetitive vertical loading under zero lateral strain: accumulation models, terminal densities, and settlement

2016 ◽  
Vol 53 (12) ◽  
pp. 2039-2046 ◽  
Author(s):  
Song-Hun Chong ◽  
J. Carlos Santamarina
Keyword(s):  
Plastic Strain ◽  
Static Load ◽  
Volumetric Strain ◽  
Lateral Strain ◽  
Strain Accumulation ◽  
Test Results ◽  
Mechanical Loads ◽  
One Dimensional ◽  
Vertical Loading ◽  
Loading Tests

Geosystems often experience numerous loading cycles. Plastic strain accumulation during repetitive mechanical loads can lead to shear shakedown or continued shear ratcheting; in all cases, volumetric strains diminish as the specimen evolves towards terminal density. Previously suggested models and new functions are identified to fit plastic strain accumulation data. All accumulation models are formulated to capture terminal density (volumetric strain) and either shakedown or ratcheting (shear strain). Repetitive vertical loading tests under zero lateral strain conditions are conducted using three different sands packed at initially low and high densities. Test results show that plastic strain accumulation for all sands and density conditions can be captured in the same dimensionless plot defined in terms of the initial relative density, terminal density, and ratio between the amplitude of the repetitive load and the initial static load. This observation allows us to advance a simple but robust procedure to estimate the maximum one-dimensional settlement that a foundation could experience if subjected to repetitive loads.

Swelling and softening behaviour of La Biche shale

1998 ◽  
Vol 35 (2) ◽  
pp. 206-221 ◽  
Author(s):  
RCK Wong
Keyword(s):  
Electrolyte Concentration ◽  
Triaxial Compression ◽  
Strength Loss ◽  
Test Results ◽  
Compression Tests ◽  
Swelling Behaviour ◽  
One Dimensional ◽  
Failure Theory ◽  
Free Swell ◽  
Triaxial Compression Tests

Free swell, semiconfined swell, and one-dimensional oedometer swell tests were performed on La Biche shale specimens in solutions of different salinities. The swelling behaviour of La Biche shale was found to be highly anisotropic and dependent on electrolyte concentration, stress, and swelling history. Drained triaxial compression tests were conducted on La Biche shale specimens subjected to different degrees of swelling. The test results indicate that the Young's modulus decreases with increasing swelling. The strength loss due to swelling can be explained by the Hvorslev failure theory. A descending power law is proposed to describe the cohesion reduction with the swelling.Key words: shale, salinity, swelling, strength weakening, modulus softening.

Viscous Property of Clay

2012 ◽  
Vol 455-456 ◽  
pp. 1532-1537 ◽  
Author(s):  
Jian Zhong Li
Keyword(s):  
Strain Rate ◽  
Water Content ◽  
Axial Strain ◽  
Constant Strain Rate ◽  
Test Results ◽  
Compression Tests ◽  
Viscous Property ◽  
One Dimensional ◽  
Saturated Clay ◽  
Rate Test

Viscous property of saturated, wet, air-dried and oven-dried clay was evaluated by performing a series of one dimensional compression tests including primary loading, creep, global unloading and reloading tests. In the tests, axial strain rate was changed stepwise many times during monotonic primary loading at a constant strain rate. Test results show that viscous property of clay with different water content under different test condition is similar. In order to evaluate the viscous property of clay, parameter β was introduced basing on the present test results of clay and author’s previous study. β value of clay with different water content under different test condition varied from 0.034 to 0.064. Test results show that β value of saturated clay is generally larger than that of dried clay.

Deformation behaviour of clay under repeated one-dimensional unloading–reloading

2015 ◽  
Vol 52 (8) ◽  
pp. 1035-1044 ◽  
Author(s):  
Apichat Suddeepong ◽  
Jinchun Chai ◽  
Shuilong Shen ◽  
John Carter
Keyword(s):  
Clayey Soil ◽  
Deformation Behaviour ◽  
Permanent Deformation ◽  
Field Measurements ◽  
Test Results ◽  
One Dimensional ◽  
Groundwater Fluctuation ◽  
Proposed Model ◽  
Oedometer Tests ◽  
Good Agreement

The deformation of clayey soil under repeated cycles of unloading and reloading has been investigated in oedometer tests using both undisturbed and reconstituted Ariake clay samples. The test results indicate that even for repeated unloading–reloading in the overconsolidated stress range, the deformation of the soil sample is not purely elastic and there is an accumulation of permanent deformation. Based on the test results, a model has been proposed for predicting unloading–reloading-induced deformation. The proposed model has been used to simulate the behaviour of a clayey soil deposit in the Saga Plain, Japan, in response to groundwater fluctuation. Good agreement between the simulation and the field measurements indicates that the proposed model can be used to predict land subsidence induced by groundwater fluctuations.

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