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9

You are worrying about the numbers and forgetting what the numbers mean. This is for the PE exam, so this is a very important topic to make clear in your mind. You solved the problem. You came up with an answer for what is required. You now have two options: Choose a small footing that your own solution just proved is too small for the requirements. Choose ...


6

From what I read, you are looking at the pressure the sand between the sheet piling exerts on them. In this case, I see two possibilities: (1) log-spiral analysis or (2) elastic analysis of Boussinesq. Log Spiral Analysis The log spiral analysis assumes that soil pressure is mobilised by a soil mass that follows the shape of a log spiral curve. This is ...


5

Beyond a certain level of saturation, the bulk modulus of water starts playing an important role. Since water is nearly incompressible at moderate pressures, the pore pressure increases rapidly and equilibrates with the externally applied force when we try to compress the water. This makes it difficult to compact fully saturated soils and partially ...


5

Here's a really (and I mean really!) quick and dirty set of calculations that might give you an idea of the magnitudes of settlement you could be dealing with. The settlement potential of the tank location can be determined a number of ways, but probably the best thing to do would be a plate load bearing test. The test can be run to simulate the range (...


4

The given information describing a compacted soil sample is as follows: initial moisture content, $\omega_{init}$ specific gravity, $G_s$ initial volume, $V_{init}$ initial weight, $W_{init}$ For completeness: the following information has already been determined: moist unit weight, $\gamma_{wet}$ using the relationship $\gamma_{wet}=\frac{W_{init}}{V_{...


3

You are correct, this is the subbase that the foundations will be built on top of. The gravel can be used as you say for water run off but it also allows for a level base on which to lay the concrete. In areas where the ground becomes highly saturated it can protect the concrete foundation from erosion. The wire mesh is usually used for load-bearing ...


2

$\require{cancel}$ A common method was devised by Davisson and Robinson (1965). By this method, what you need to determine is the "length of fixity", which is given by $$L_f = 1.8\left(\dfrac{EI}{n_h}\right)^{0.20}$$ Where $EI$ is the pile's stiffness and $n_h$ is the soil's coefficient of horizontal subgrade modulus. This is the relevant length for a ...


2

That water you have described where the ground is wet but the lower ground at the foundation levels were dry, is generally not going to cause significant problems because the weight of the water will cause the water to migrate further down the ground, until such that it is held up by capillary action. Given such, the addition weight of the water coming from ...


2

Depending on the type of soil at your site, moisture content under the foundation can change depending on the change in surrounding soil. The typical footing depth in the majority of cases will be enough to create some acceptable equilibrium below the level of the earth icing to handle moisture content changes in non expansive soils. But for many ...


2

A structural engineer should never conduct their own soil testing unless being supervised by a competent person. This is not your area of expertise, let the geotechnical engineer do their job. Generally the geotechnical engineer should outline any risks specific to the site that way other engineers can design for them. An example of this would be ...


2

If the excavation has a slope of roughly 3 vertical to 1 horizontal, that's about 70 degrees with horizontal. An unloaded slope in stones, gravel or sand will not be stable at an angle of more than approximately 40 degrees with horizontal, so it is not possible to make the excavation without disturbing the soil. That angle is called the angle of internal ...


2

Usually since hydrostatic pressure along with freezing and thawing are such a pain (quite hard to figure out the pressure from freezing water in soil), in practice I try and keep my retaining walls 100% water free. However, if you were to design the wall for lateral earth pressure of clay + water table pressure, I found in my old notes some active, rest ...


2

For a given compaction energy, this is a volumetric problem. Keep in mind that we are working with a given volume (say 1 cubic metre) of dry particles (solids), water and air, thus: Compacted soil = dry particles + water + air Dry particles, for example sand (cohesionless soil), as oven dry, can be compressed to form a granular skeleton that contains air ...


2

The PRESUMPTIVE LOAD-BEARING VALUES table in the IBC is meant to be used with ASD loads (see section 1806.1). As such there are already factors of safety "built in" to those values. The only thing I am aware of that the IBC has to say specifically about shallow foundation settlement limitations is in section 1808 (not even worth quoting). The values in ...


1

In general, $F = q_S * A_contact$ https://hetge.com/files/PilesCapacityRefMan130403.pdf


1

Terzaghi's $ \sigma=\sigma' + u $ assumes 8 conditions. One of the assumptions is that the voids are interconnected and there is no air pockets. Hence the hydrostatic pore pressure and the implied buouncy force. Some of Terzaghi's assumptions don't hold in experimental results. See Wikipedia page. Terzaghi's


1

Percent finer is the amount of material from a sample that is smaller than a certain size. On the example table provided, the Sieve No. 12 (150 micron) has a % finer of 18.2%. This means that 18.2% of the material passed through that sieve, and 81.8% (which is 100% - 18.2%, which you can see in the "Cumulative Retained" column) was "caught", or retained, ...


1

I would use a Shear Box test for this. Stress testing is for maximum load-bearing capacity... Shearing is what gives you the modulated graphic results you seek. Have a look at Smith's Soil Mechanics 9th ed for more details.


1

Unconfined compressive strength test is generally a undrained soils test. The issue with a constant load machine is that you will likely load it too quickly as well close to the failure point, which will produce inaccurate readings and measurements at failure (i.e. you will end up missing the point of failure, and needing a new sample again). Otherwise, the ...


1

I am going about explains this question at the level of high school physics. Let's assume you auger blade covers 2 full circles at length of embedment of 1.5 feet. And assuming the radius of blades 6 inches the diameter of the bore as 1 foot. So the surface of the earth resisting torsion is either $1.5\pi\times1 = 1.5\pi$ feet or a expanded ...


1

You have to run the test at various moisture contents. Plot the number of hits vs. moisture content and then extrapolate to 25 hits to find the moisture content at the liquid limit. The ASTM D4318 standard should be followed. However, there is always some operator-dependence and an alternative is the cone penetration test described in BS 1377-1/2.


1

Assuming you mean petroleum; crude and products are collected as much as possible , and taken to the refinery for processing. In much of the world , what can not be collected is burned in situ, this was formerly done in the US also. Today, in the US , regulations create a problem and contaminated soil is dug up and hauled someplace for cleaning . The burned ...


1

Instead of trying to add insulating coating to the metal tube, I would try to get rid of the tube that protrudes above ground. The tube would serve as an introduces for the sensor. The tip with the sensor could be designed such that it stays on the tube as when you push, but separates from the tube when you pull. Or try to interrupt the thermal conduction ...


1

I don't believe there is any fundamental difference between intentionally frozen and naturally frozen soils. Other than control of the temperature. I'm afraid the mechanics of soils (frozen or otherwise) is complex and depends on many factors such as the soil type, water content, grain-size distribution, compaction, etc. The soil properties used for design ...


1

Look at the typical diagram of soil showing soil/water/air: Simple Thinking simplistically about it the items that could change: Soil mass can't change. No soil was added. It would be good to assume that no major chemical reactions occurred either. Water mass can change. It was sitting in water. Air can't increase if the sample was submerged. Once again ...


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