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Soil Compaction - Science topic

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Soil compaction
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Dear Sir
The cited equations for determining soil compaction commonly include Proctor compaction test (ASTM D698) and Modified Proctor compaction test (ASTM D1557).
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Is the number of passes to control the quality of compaction too extensive?
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Some countries do not have up-to-date data
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Compare and contrast the different methods for assessing soil compaction, such as bulk density measurements, penetrometer tests, and visual assessments. Evaluate the strengths and limitations of each method, and their suitability for different soil types and land uses.
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Find the doc attached
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Describe the physical and chemical changes that occur in compacted soils, and the factors that determine the extent of compaction.
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Reduced pore space results from the compression of soil particles during soil compaction. This can be brought on by human activities such as farming or building, or it can happen naturally owing to elements like rainfall or the weight of heavy machinery. The quantity of air and water that soil can hold is lowered when it is compacted because the pore space between soil particles is reduced. Due to the fact that plant roots require both air and water to grow correctly, this may result in diminished soil fertility. Compacted soil is less able to absorb rainwater, which over time can result in erosion and deteriorated soil health.
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please share statistical data to support answer to my query
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Further to the question, the max dry density (MDD)kN/m3 is only achieved at optimum moisture (OMC)%!
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I would like to create artificial compaction on soil which is covered by special plant species.
Which tools and/or formulas can be used? 
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can you solved this problem?
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We are trying to get the best compression and consolidation in making Compressed Earth Blocks. Any suggestions on how to optimise the soil composition to get best packing density will be most appreciated.
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Clay loam soil. Theoretically, for maximum compaction there should be an equal proportion of sand, silt and clay fraction, i.e. 33 per cent each. But in nature, it hardly happens. Therefore, try to have proportion within 10 per cent deviation among these fractions to have maximum compaction. Yes type of clay particularly, swelling type is also the factor which determine maximum compaction at given moisture content. Proctor moisture shall be used for achieving highest compaction. May contact further on vkphogat@gmail.com. thanks
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I need to know what tillage systems out there cause the least soil compaction. It'd be great if there were references I could cite. I want to compare tillage systems and how much soil compaction they cause (if that would be possible).
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zero tillage
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As a function of dimensions of real projects?
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Feel free to get in touch with me for more explanation.
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Let me introduce myself, my name is Cindy. I am a graduate student and I'm currently study soil organic carbon in Mangrove Forest.
I would like to know if it is possible to measure dry bulk density in disturbed soil (sediment was taken in depths 0-15 cm and 15-30)? The condition was soil compaction occurs, I only able to took 300 gr wet sediment from each interval for analysis, I didn't take the rest due to transportation difficulties.
Hence, the volume of sediment will be using this equation
sediment volume = (weight dry sample/sediment particle density)+(weight wet sample-weight dry sample) (Avnimelech et al., 2001)
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Many researchers have given the values of OMC and MDD for bentonite based buffer materials corresponding to heavy compaction (higher compaction energy).
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In expansive soils, swelling increases with increasing dry density and decreasing moisture content. Therefore, standard compaction is better to be used for expansive soils to reduce swelling problem.
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Hi there, 
what is (are) the  benefit(s) of  drawing the zero air voids with the compaction curve(s)  ? 
Thank you  
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In compaction curve, the zero air void line which is a line of 100% degree of saturation drawn on the right side of the compaction curve without touching it. this line helps to check that the plotted compaction curve is correct.
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QUESTIONS
1) It is known that anything that is overturned is screwed onto something solid to prevent it from tipping over.
Why civil engineers do not screw the sides of the walls on both sides, with the ground?
The overturning of the walls deforms beams and walls until it breaks them;
Do you like to break concrete?
2) Bending is a second deformation factor that breaks the cross sections of the bearing elements.
It is known that the bilateral pre-tensioning of the sides of the walls when they have suitable cross-sections eliminates the bending.
A combination of strong ground anchorage and at the same time pre-tensioning of the sides of the walls from their upper levels with tendons without relevance would stop overturning and bending which are the only causes of deformation and we know that deformation and failure are interrelated concepts.
Do you want distortion and failures?
3) Intersecting If in the cross section of the wall we impose compressive intensities of 70% of the breaking factor, we increase the strength of the cross section by 40%.
Why do you use the mechanism of relevance as the main reinforcement and not tense walls?
4) We all know that deformation creates inelastic failure.
We mentioned the overturning of the wall and the bending of its trunk as causes of deformation and failure of all load-bearing elements.
However, deformation and even very serious can occur due to inhomogeneous subsidence of the soil.
The ground is inhomogeneous, by nature, with different support strengths at each base.
Soil sampling is required at each base foot, and if necessary soil compaction is required to increase the soil's ability to support the base.
However, due to cost, it is rarely applied and if it is applied, it is done only in great projects.
5) The non-prestressed connection of the sides of the walls with the ground diverts the seismic intensities, leading them on the cross sections.
The prestressed connection of the sides of the walls to the ground from the top level with unrelated tendons diverts the seismic intensities, leading them into the ground.
Why not apply this design?
No more excuses.
The absolute seismic system and the method that follows ensures little deformation and no failure as it controls the overturning and bending of the wall, increases the resistance of its cross-section to cut, ensures sample ground control before the construction of the project, and creates a very strong support strength of construction after compacting the foundation soil.
These are all fundamental laws of engineering, and you continue to design wrong.
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Very interesting question...worth following.
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I was wondering if there are any specific guidelines for the preparation of artificial soils in laboratory. In general we tend to add some different soils and make a blend of a new soil with distinct properties but somewhat corresponding to the parent material. Is any research available on the preparation of the same apart from use.
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Hello, if artificial soils are intended as the preparation in lab of mixed basic components, some steps should be respected, as multicomponent blend:
- definition of real scale grain size distribution;
- level of compaction and water content to set initial parameters for testing;
- scale laboratory effect to evaluate the amount of mass necessary for the artificial mix;
- in case of excess of coarse material, separate the large diameter classes but take into account for influence of some parameters (mechanical or operational)
- take care of requirements of homogeneity during preparation but in the meantime consider what will happen in reality during operation (dumping, mixing, compaction, long term aging or clogging, etc).
The hydraulic and mechanical properties of soils depend on physical and chemical interaction between particles.
These are only suggestions as each case should fit specific site and design condition for the intended use (drainage, paving, backfilling, subgrade etc) , starting with classical geotechnical testing procedures for sample preparation.
Regards
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Assuming other factors non-limiting crop yield, focusing on soil physics, and looking for indicators of soil physical quality: can the degree of compaction (Bulk density/maximum or reference Proctor bulk density) be a universal indicator for crop yield?
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Soil compaction is just one of the soil physical properties that affect crop yield. But different crops have different sensitivity or tolerance to soil compaction. A case in point is rice. It thrives well in puddled soil whose structure has been destroyed and compacted by field operations (e.g. plowing, harrowing) when the soil is saturated with water. In addition, the degree of soil compaction affecting the root system of plants greatly depends on soil texture, structure and other soil properties. Thus, to make soil compaction a universal indicator of crop yield is, in my opinion, not feasible.
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How to set the sampling point reasonably and effectively to ensure that the geological statistical method can effectively analyze the spatial distribution characteristics of the compaction quality of the soil?
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Hello everyone!
I have been doing Level 1 Inspection & Testing for Soil Compaction in the field. The compacting material is basically, CLAY. I use nuclear gauge to measure the field density and moisture.
I wanted to have the expertise suggestion on "how can we say if the moisture is OK or NOT or simply if the moisture that is used for compaction is within the design limit like +_2% or +-3% of OMC". I usually, use this feel method by hand but that is way too confusing to tell and it's subjective. Yes, there is one method to tell that is carrying out one dummy test, however, by the time the dummy test finishes the lifts would be laid and compacted.
So, I was wondering if there are any suggestions in this regard from the experts. Even if the method is feel based, I shall be thankful to have a bit more explanation so that I can implement in the field from next time.
Thanking you in advance.
Sumit Maskey
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By feel and squeeze one can tell if the moisture in the clay is workable or not,once clay is sticky it means it has more moisture than the OMC and when clay is squeeze and the bond between its portion can be broken easily, it means the moisture is below the OMC, so its all about striking the balance while you are at site.
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I compacted unbound aggregates at optimum moisture content and then let it dry in the oven for one day. The repeated load triaxial test was carried out on this sample in which I faced a weird behavior (please find the attached figures). The permanent deformation initially increases with a high rate and then its rate decrease slowly and finally it has a negative displacement (like expansion).
This behavior only happened in dried samples and the lower stress conditions (1.59 KN and 1.767 KN deviatoric stresses and 120 and 41.7 confining pressures). These samples have normal behavior, the permanent deformation keep increasing with load cycles, at higher loading environment.
I appreciate your time.
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Cohesionless soils when sheared at low confining stress will dilate and generate negative pore pressures. The particles are interlocked but at some point of continued axial stain they must lift to ride across one another. The perfect example can be seen in the direct shear device with vertical axial stain measurements. Taught in basic soil mechanics. At high confining stress soil is contractive. Dense soil is dilative and loose soil is contractive and depsnds on confining stress.
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Which statistical test is appropriate to test the following hypothesis?
H01: There is no difference in soil compaction across all locations (e.g., Location A, B, C, D, and E). No zeros.
H02: There is no difference in the total number of small mammal burrows across all locations (e.g., Location A, B, C, D, and E). Many zeros.
Each location consists of 7 plots that are located apart from each others and each plot is divided into quads. burrows are counted within each quads. therefore, enormous number of quads have zero counts. Sample size are not equivalent and data are not normally distributed.
Since the variable is independent, I am thinking of using multiple Mann-Whitney U test to test my hypothesis:
burrows in A versus burrows in B
burrows in A versus burrows in C, etc.
I will really appreciate your help
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If the Kruskal-Wallis and/or the Anova tests are significant, run a Post Hoc test. These are sufficiently available in most statistical software packages.
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I mean after doing the compaction practice in various water contents and determining the dry density corresponding to each water content, what would be the equation of the resultant compaction curve? Assuming that there should be only one optimum water content, I think the quadratic curve can be the best option to fit the bell shaped results. However, I could not find anything in the literature (the compaction curve is drawn without presenting the equation or a line simply connected data).
I was wondering if you could introduce me any reference about this matter.
It is a matter of great importance to me to determine the optimum moisture content consistently for all of my materials.
I attached my data and the quadratic curve passing through them. could you please let me know what is the optimum moisture content in these compaction data series and what is the compaction curve for them?
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These are the questions I faced in my literature review I could not find an answer for them. Just for the record, I am going to do the CBR test on laboratory compacted base materials in the pavement.
1- In which moisture content and dry density this test is accomplished (generally for the scientific purpose). I mean, CBR can be employed directly after the compaction or after soaking in water for four days. Should the CBR test be done with various moisture content? Should it be done in 95% of MDD (as the compaction in field is usually 95% of compaction in the lab)?
2- What is the number of layers in the compaction process (if the vibratory hammer is used for the compaction)? 2 or 3 layers?
3- What would be the weight of surcharges if the pavement design includes an asphalt layer of 10 cm and a basecourse of 30 cm and the materials are to be used in the base layer?
4- While soaking aggregates in water, what should be the elevation of water above the sample?
Kind regards,
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You can refer to AASHTO T 193.
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I need research articles on management of compaction of soils testing 3, 4 or more years. Significance differences between treatments is I´m looking for.
What do you think that are the effects and results of testing ?
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Based on the New Zealand standard the specimen height should be 125- 127 mm. My question is that what if the resultant height of the sample after the compaction was more than or less than this amount. I asked it because there is a height correction in Marshal compaction method of Asphalt materials. I thought there should be something for the compaction Unbound Materials.
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Vibration compaction tests include vibrating table test and vibrating hammer test.each method will give different results though dry unit weight and water contents are the same for a given granular soil.
However it has been suggested that impact factor be used and its result must be considered.
There is no index for correction for vibratory compaction.
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I'm looking for any labs working on these topics, articles or tools allowing to measure such data, more especially in agriculture.
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This will be applicable to most of the soil inhabited microbial communities..not only bacterial community...
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We planned to take some samples from the area where wheat is to be grown in future. The area was laser levelled recently and not cultivated for some time.
It was very hard to take soil samples and the soil was very dry too (it should be at field capacity I believe).
Now, what strategies should be used to improve soil conditions for easier sampling?
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Sampling with auger in hard soil may require specific type of auger and accessories. The following links may provide clues to select the suitable tool and accessories:
The video in the following link may also be seen:
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Now i know that soil structure is destroyed resulting from activities of constant soil compaction (example vehicles, humans or animals going over a piece of land regularly) thus leading to loss of vegetative cover of the soil (making the soils bare). But when the area that lost its vegetative cover due to constant soil compaction is left to fallow over time without any interference/hindrance. The soils recover and grasses, weeds that could not withstand or survive in such soils begin to blossom and flourish
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Thanks J.
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In soil compaction test, if a test result exceeds 100%, should engineers accept the result?
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It is under conditions not only accepted but also required.  For instance in railway embankments, UIC 719R requires that for the prepared subgrade should be compacted to or above 100% of the maximum dry density as determined from the Standard (NB 95% of the Modified) Proctor Test.  However, for the blanket layer it is expected that compaction equals of exceeds 100% the maximum dry density as determined from the Modified Proctor Test, depending on design speed and local regulations.  In Greece for instance, the prepared subgrade is expected to be equal or above 100% of the standard Proctor, whilst the blanket is expected to equal or exceed 103% of the standard Proctor value, for ballasted track and design speeds above 160 Km/h.   
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Hello every one,
I want to conduct direct shear test on rubber recycled products such as tire chips. I studied different articles that referenced ASTM D 3080 for doing direct shear test on these particles. According to this standard, compacted specimens shall be prepared using compaction method, water content, and unit weight. I suppose proctor compaction test is not correct way to understand how much to compact rubber particles in shear box.  If anyone has experience or references in the direct shear tests on the rubber particles, please share it.
Many thanks.
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i agree with Madhavi
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Hello all,
My master thesis is on soil compaction simulation using DEM and for calibration of the contact model, I use Oedometer test. I simulate the Oedometer test and compare it with experimental values. The material properties of the calibrated oedometer simulation is then used in the soil compaction simulation. In Oedometer test, I use particles of radius 1mm. However, to reduce the computation time in soil compaction simulation, I scale the radius of the particles 10 times the original value(i.e. 1cm). Therefore. I should also scale up the material property values. I would like to know whether there are any relationship between the radius of the particle and the material properties like stiffness, friction coefficient etc. Thanks in advance.
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Hello,
According to User manual of PFC3D (2005), sphere particle stiffness  is related to the radius as follows: 
k=4ER, where k= stiffness, E=Young's modulus, R = mean radius of two contacting particles.
Hope this helps. 
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Soil organic matter (SOM) is renowned for being the best indicator of soil quality, due to its capacity of improving stability and sustainability of agricultural and forest systems, as well as the fact it is sensitive to changes caused by agricultural practices such as soil tillage, soil compaction, erosion, liming, within others. However, the simple measurement of the total SOM (Walkley-Black, Yeomans & Bremner, dry combustion method - CHNS/O Analyzer) has not been sensitive enough to detect small changes in the soil. Thus, many SOM fractionation techniques have been used for this soil quality diagnosis purpose, such as SOM light fraction, SOM heavy fraction, carbon of microbial biomass, etc. However, most of these methods are expensive and difficult to be performed in large-scale monitoring programs. So I wonder if you know among the SOM fractions, which one(s) are those with better correlation or sensitivity to soil disturbance due tillage or crop system? Which of the SOM attributes would you recommend to be monitored in the long term programs, considering the operational feasibility (field soil sampling and lab analysis) and low cost?
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Interesting discussion . Sensitivity of soil organic matter fraction is largely guided by ease of extraction , active fraction  ( For example humic acid , fulvic acid as part  POM of SOM ) is more labile in nature , and hence contributes towards soil structural stability . Any reduction /depletion in these fractions would indicate loss of soil stability or potential degradation..Loss of organic matter binding soil particles means  soil is fast approaching towards degradation
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What young's modulus could I adopt for colluvium/talus deposit (Silty sand with some stone blocks, Nspt= 5 - 20)?
The layer is 20 m height, slope angle 15°
And about Mohr-coulomb strength parameters, C and Ø?
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I think you could look at some basic correlations for soil. The Bowles soil mechanics textbook has lots of good rules of thumb for correlations with SPT N.
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Hello all, we want to restrict the lateral displacement of diaphragm wall. Due to the vicinity condition, we cannot use tie back anchors. In this regard, we offer T type diaphragm walls, however, this proposal are not cost effective. Anyone has another suggestion. Your help is greatly appreciated.
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Thanks for your valuable comments and suggestions which have led to significant improvement on the quality of proposed design. As a first step, we decide to analyze the combination of T shape diaphragm wall, and using the berm, secant wall and rakers during the excavation. Then, investigate the effect of other methods like jet grouting the behind of the wall or using the pre-stressed diaphragm wall. However, I'm interested in finding out your other offers.
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I have come across work of P.J. Yoder (1980) (A strain-space plasticity theory and numerical implementation). He made a strain-space equivalent to pure plastic Coulomb model. His model has the following benefits (according to Yoder P.J.):
  1. Return mapping is eliminated (A very provoking statement, but he shows the maths behind it as well as detailed comparison of simulation results).
  2. Global stiffness matrix inversion count is reduced (significant step forward, for dynamic / cyclic loading application)
Despite dramatic increse in computation efficiency, Yoder's work did not go mainstream. (perhaps you can you spot why?)
I am intrigued by his work as during recent triaxial testing we were able to control sand stiffness through controlling applied strain (deformation) history. Yoder P.J. has explicitly called for a "rationale to the strain space problem", and we appear to have found the missing experimental "rationale" .
We found strain (not stress) dependant soil patterns, which capture and allow full control over loss and recovery of drained sand stiffness. Also, post-liquefaction soil stiffness recovery, and we can impose post-liquefaction soil state during drained loading. We seem to be closing the gap between drained, undrained and partially drained sand, but the new findings explicitly call for a strain-space plasticity formulation.
Any input is greatly appreciated. Any links to strain-space models or strain-dependant observations of sand (such as liquefaction charts by R. Dobry, or plastic spin (strain) tenstor by Y. Dafalias). This topic is not covered by "mainstream" geotechnical curriculum, thus I don't expect many answers. But every answer and question on the rare subject is appreciated.
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Hi
OK, you have gotten rid of the bubbles in your test.  :) The thing is that it takes time form cavitation while a shock wave can accumulate quite fast.
What about bubbles in real life conditions?
Looks like your will have fun with your data. Congrats.
/C
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I want to measure the suction for an unsaturated material in a triaxial testing device. The suction tension for the material should be less than 1 MPa according to a small literature review I conducted. I know that there developments which use an osmose method. Are there good pressure transducers which are also able to measure the suction?
Another question is if the applied confining pressure will superimpose the suction tension.
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Dear Mrs. Nirmala,
thank you for the papers.
Dear Mr. Moghadam,
thank you for the hint.
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Hi !!
I am working on Stability of unsaturated soil slopes due to infiltration, but I have convergence and numerical oscillation problems … This oscillated pore-water pressure distributions do not appear realistic, as they indicate drying of the soil, which is unlikely with an influx boundary condition. 
Has anyone had similar problems?... Is there a relationship between the element size and the time step, that allows me to solve these problems?
Thanks for your help.
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 Hi Bestun and Hossein, thank you very much for your answer:
The truth is that so far I'm working on the infiltration analysis and later I will start with the stability analysis , so your answer will be very useful to me in the future.
In the picture attached is observed a little better the problem: The initial distribution of suctions (step 0) is observed and variation in suction when a rain of 0.1 m / day at the soil surface is applied; the problem is that over time the suction increases rather than decreases. I read some articles about it and I think it can be a problem of numerical oscillation. 
I have understood that SEEP is excellent for flow modeling, but now I only have PLAXIS 3D to develop my thesis.
I am Spinning around the matter and so far I don´t know how to resolve it, so I appreciate any help you can give me...The models are three-dimensional
Thank you again
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hii
hii 
I happened to find in some journals as well as for my thesis that the ultimate uplift capacity of pile groups increased drastically when the pile dimension changed from intermediate to long pile (in my case as L/D changed from 24  to 34 the ultimate uplift capacity changed from 148N to 300N whereas for L/D 14 its juz 50N) what could be the possible explanation for the above behaviour??
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Hello Aswathy,
Could you tell me a little more about your problem? In your scenario of L/D ratios, is D or L constant? That is to say when comparing L/D = 14 to 24 to 34 is the  length of pile increasing or diameter decreasing or both? If you can provide a summary table of values of L and D and capacity that would be great.
Thanks,
Robert
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Hello 
Does anybody have an idea why do we use 25 blows in the standard compaction test ?
As well as why do we compact with 3 layers ?
thanks 
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Proctor was doing road development projects where he needed to estimate the practically possible density of soil, which is different from theoretical density. He tried to solve this through laboratory tests by using various moulds and compactors and different combinations of blows and lift thicknesses. In this process he settled with 25 blows and 3 lifts.
The original Proctor Compaction Test of 1933 used cylindrical mold 4 inches in diameter and 4.6 inches high, with a removable mold collar 2.5 inches high. The mold volume is 1/30th cubic foot
A 5.5 pound hammer, 2 inches in diameter, was pulled upward and allowed to free-fall 12 inches, onto the soil (5.5 ft-lbs per blow)
The soil was compacted in three lifts, with an average thickness of 1.33 inches/lift.
25 blows were exerted per lift, which equals 25 x 5.5 = 137.5 ft-lbs. The total input energy for the three lifts was 3 x 137.5 = 412.50 ft-lbs on a soil sample with a volume of 1/30th cubic foot. This equals 12,400 ft-lbs of compactive energy per cubic foot of soil
This energy simulates the field compactive effort closely and hence he settled for this. Read the enclosed document for more details on the development of this test.
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The image provides test results classifying the soil.
Thanks
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Hello,
There are many correlations available in the literature which correlates the compressibility index of a soil with its plasticity properties. You can find many by google search.
However, many use Terazaghi and Peck's formula Cc = 0.009(LL-10) for quick determination of Compression Index. Please refer to the paper attached, which tabulates different correlation between compression index and plasticity properties as mentioned in different literature 
Regards
Sravan MV
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According to classical soil mechanics we generally consider the distribution of stress caused by a uniform surcharge loading, to stay constant along with depth. However, the stress distribution caused by a spread footing is considered to decrease with depth (generally becomes around 10% of contact pressure at 2B and 4B for square and strip footing respectively).
While designing an excavation retaining system with an adjacent building resting on strip footings, a common practice is to consider the building load as surcharge load (i.e. having an earth pressure diagram with constant abscissa). If this assumption is correct, then how is such earth pressure diagram different than earth pressure caused by a uniform surcharge (e.g. overburden extending to infinite extents).
Or in other words, how is the earth pressure on a retaining structure caused by an adjacent strip footing different than the earth pressure on the same retaining structure due to an adjacent surcharge load?
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Thanks Erion for the help. I agree with your opinion.
I think it is the limitation of manual calculations and the assumption to consider the adjacent building's load as the surcharge loading of infinite extent is merely for simplification purposes. And the design, in this case, would be on the conservative side.
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I don't know of many farmers routinely employing a field-wide evaluation of soil compaction, but when I do it's always wtih a penetrometer. Some sample a few points and believe that behavior reflects the whole area (a true statistical inference error, in my opinion). Others take samples not paying attention to soil moisture. I don't know, isn't there a better option or instrument?
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Hallo Tiago,
According to your question I can give you the following reply: 
Suitable parameters to assess the soil compaction are i)  saturated water conductivity, ii) effective bulk density (= bulk density + (0.009 * clay content [%]  ) by pF 1.8 and 2.5, iii) the macroporosity by pF 1.8, iv) penetration resistance (dynamic - Panda sonde) by pF 2.2 - 2.7. The penetration resistance alone is not enough to assess quantitavely the degree of soil compaction.
Basically, the penetrometer is an excellent and an appropriate intrument to measure the hardness of the soil or wearing capacity of the soil (different from degree of soil compaction). Only with one parameter (penetration resistance) you take into consideration at the same time soil texture, soil sturcture, soil moisture,  ground cover, root density to evaluate the soil  trafficability.  We have observed that in special cases a wet soil (permanent meadow) can be harder than an arable dry soil...
Penetration resistance is an imortant parameter to describe stress propagation in the soil. Penetrometers are not predestinate to assess directly the degree of soil compaction.   
With my best regards,
Etienne
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Do these practices make soil aggregates even less stable? What else could be employed in order to fully reverse soil compaction, if that'd be even possible?
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Dear Thiago Villa, Dr. Nils Borched has correctly replied. Subsoiling or disking do limit the compaction but effects last for 1-3 years depending upon the lime contents, OM, texture, irrigation water quality, chemistry  and mineralogical make up of soils. To sustain the de-compacting effects of any mechanical or mechanical soil treatment, please look into the factors inducing compaction.
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And, if so, why are they not effectively replacing tire tractors?
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This is a complicated question to answer. On a like for like basis, where you have two tractors exactly the same, the one with more surface area contact to the soil will have a lower foot-pressure ratio, so a larger tire or tracks would, theoretically, be better. However, the ability to drive the tracks (or a larger tire) requires an exponential increase in the power of the engine unit and more substantial drive train, increasing the weight of the vehicle. So in order to achieve the same outcomes as a 'normal' tractor, using a tracked vehicle requires a larger vehicle with substantially more weight and subsequently greater soil compaction. 
While this is a limitation on the employment of tracked vehicles, it is not the full answer on why they are not more widely used- two other factors need to be considered. First is the turning circle and the resultant impacts. A tracked vehicle can theoretically turn within its own radius, often less, but the churn in the soil and the risk of throwing a track increases substantially. A less dramatic turn results in a turn outside its diameter (If you drive the vehicle in a circle, the resultant distance across that circle is described as its diameter, half that diameter is its radius). While this is substantially true for most vehicles, especially large ones, the difference when using tracked vehicles of a similar size is substantial. This not only requires greater amounts of POL but also increases wear and tear. 
Which brings us to the other problem with tracked vehicles- the wear and tear on drive trains and engines is substantially greater, requiring both detailed maintenance which cannot be readily provided in a farm environment and regular replacement if the power to weight ratio is to be maintained. The power to weight ratio is important in tracked vehicles as even a minimal drop-off can result in drive failure, where the tracks cannot be made to complete a full revolution in order to propel the vehicle. Moreover, throwing a track requires far more time, skill and equipment to repair than is required to replace flat tire on a tractor. Rubber tracks have been used in recent times to try and overcome this problem but this requires more maintenance and results in shorter replacement times for the drive wheels and return sprockets. 
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What changes can one make to their crop system in order to minimize soil compaction? Is there a paper/review addressing these measures?
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I want to evaluate failure of slope in a shale formation but get faced with continuous washing of the slope face due to high incidences of rainfall.
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Thanks Kundan and Trivedi for your response and for the attached papers.
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Hello Dear Engineers
I need the data points of Volumetric strain vs. effective shear strain by Tokimatsu and Seed (1987), This curves used in liquefaction computing of soils.
I Found the paper and image of the curve and attached here but I couldn't found any data points.
Would you please provide me with the data points of this curves?
Thanks
Yours faithfully
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Dear Ahmed,
Would you consider equation y=x+0.7 instead of y=0.7-x?
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I'm designing a benchtop experiment for a soil physics class. Students will use a small-scale soil penetration resistance probe to assess soil compaction. I have soil pots I wish to compact to known compaction levels. Question is: How?
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Use hollow steel plates that will give you the required pressures(static dead weights).Then insert your penetrometer in the soil sample and measure the penetration resistance.
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tiles dust and lime are effective to increase the shear strength of alkaline soil
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lime treatment will aid as s water repellent short term treatment
dust what type of industry what are the characteristics of it has to be defined first
There are some industrial wastes which  are increasing sbc of soil
I do agree with Mr.Ahmed  sahil
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We have a dam embankment and it has been affected by dispersive phenomenon in the laboratory scale test and the process continues still today in all borrow sites. (We cannot change the borrow site)
I want to asses this internal erosion process (rates of subsidence and detachment of soil particles). I will be very grateful if you could recommend some applicable case studies for this problem!.
Regards,
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Hi,
Chemical treatment, adding lime, etc would be considered as some alternatives. You may search for "treatment of dispersive soil" to find useful documents. Check also the following:
Regards
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I would like to know the compactive effort (size of the rammer, height of dropping and number of blow) to use to remould disturbed soil sample into its natural state in other to carry out remediation of contaminated soil in the laboratory.
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Depending upon resources that you are able to access you could simply use a bulk density hammer with a piece of wood cut to the size of the mold (a bucket or smaller tray) the soil will sit. Basically do  a days worth of experimentation,  slowly compact the soil with a many drops of the hammer over time. The take a BD sample to see if you have what you want, or measure the compaction with a soil penetrometer afterwards.  Match the compaction or bulk density to the field conditions of the site you aim to remediation. Have fun experimenting. Attached is a classic paper on physiochemical parameters of  forest soils productivity. 
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p-rem? other suggestions?
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Yes that what I meant i.e. AEC!
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I want to model the tunnel long-term deformation in soft soil with soft soil creep model in Plaxis 2D
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Sorry for my poor english.
I think who you could be analyse what are your phases of excavation, as first step.
After this, the tunnel is constructed. Then you could search for articles for specific soil, in this case soft soils of your region, and can be consider the phases in according to significant difference of displacements (test e.g. 100 days, 1 year, 10 years, 100 years... and measure the difference of settlement).
Attention is drawn to the waterproofing account (submarine or umbrella) and their representation in the model.
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I did some compaction tests with variations of PP fibers. As the aspect ratio decreased, the OMC increases. Is it possible, or should I repeat my tests?
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We have a paper showing how OPC of compacted soil changes with increasing fiber content. Our data show show that OMC increases when fiber content increases from zero to 0.8 or 1.0% and then decreases when fiber content exceeds this value (Please see our paper published in Water, Air and Soil Pollution 2007). This range of fiber content may be considered as a threshold value in terms of compaction characteristics, and its value may depend on the soil type, fiber length/type. 
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I am studying the unsaturated soil compression, but I found the degree of saturation of soil did not change with the vertical loading 10Kpa. I think maybe I did not set the right the water level. Could you give me some advice about the water level setting?
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Soil compaction.
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In several cropping-areas of the world the smart / gentle compaction of the soil by flat- or ring-rollers after seeding is common practice in order to enhance the re-establishment of capillarity after plowing or tine-tilling and thus promoting the humidity-flow towards the seeds required for germination. This can be valid for most seeds. In simple field-tests you can varify the impact.
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I need to model the porosity that will be encountered during compaction of particles consisting of different shapes (not spherical) as determined during SEM analysis.
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Dear Gerrit,
I do not know where is freeware for the mentioned problem computation.
At the same time, I propose that our paper published in 2000 in not very popular Journal "Scientific Israel" may clear some peculiarities of this process. You can download this article at the ResearchGate.
Aleinikov, A.L., Belikov, V.T., Eppelbaum, L.V. and Nemzorov, N.I., 2000. Mountainous rock destruction and metamorphic processes in the Earth: A view from classical physics. Scientific Israel, No.3, 65-87.
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Ng and Pang (2000) stated that increasing the surcharge causes increasing the air entry value in SWCC, but I think it is reverse because increasing the surcharge will decrease big pores of a soil. What is your point of view?
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Check section 4 of the following paper, that uses similarity between SWCC and SFCC:
 Azmatch, T.F., Sego, D.C., Arenson, L.U., and Biggar, K.W., 2012. New Ice Lens Initiation Condition for Frost Heave in Fine-Grained Soils. Cold Regions Science and Technology. 82, 8–13.
Check the following paper as well:
 Azmatch, T.F., Arenson, L.U., Sego, D.C., Biggar, K.W., 2012b. Soil freezing characteristic curve of Devon Silt. Published in Proceedings of the David C. Sego Symposium, University of Alberta, Edmonton, Alberta, Canada, April 26–27.
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Sometimes I am confused about permeability and diffusion during drying of food material.
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During diffusion the molecules move from the region of high concentration to that lower. During drying water diffuses from internal regions (with a high moisture content) toward its surface (with low moisture content) where it evaporates if sufficient heat is supplied and the second Fick’s law described its mechanism but Fick’s law have several theoretical limits in describing diffusion mechanism. Some researchers consider food as porous media and defined food as biological material volume, consisting of solid matrix with interconnected void. therefore Capillary forces flow must be considered as one of the most important mass transfer mechanism during drying. Capillary flow in food may be expressed by Darcy’s law (1).
[Should be noted, permeability is a kind of diffusion from polymer film or layer which is porous. As a Conclusion, water transfer from internal regions toward dry surfaces with Capillary flow, interconnected void, is named Permeability].
I think this is a good reference with additional information.
Reference:
1-Derossi A., Severini C. and Cassi D. (2011). Mass Transfer Mechanisms during Dehydration of Vegetable Food: Traditional and Innovative Approaches, Advanced Topics in Mass Transfer, Prof. Mohamed El-Amin(Ed.), ISBN: 978-953-307-333-0, InTech, Available from: http://www.intechopen.com/books/advanced-topicsin-mass-transfer/mass-transfer-mechanisms-during-dehydration-of-vegetable-food-traditional-and-innovativeapproaches
I look forward for your opinion.