# Questions tagged [soil-mechanics]

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### How does the maintain load test work?

A project site in my company is currently working on testing the settlement of our piles using the maintain load test, so my boss is asking me to find out some information on this. In particular, he ...
77 views

### Geotechnical engineering: The $\phi=0$ concept

I am reading B.M. Das' book: Principles of Geotechnical Engineering, 6th edn. In the chapter concerning shear strength of soil the $\phi =0$-concept is introduced.$\phi=0$-concept" /> In an ...
33 views

### Geotechnical engineering: What does a negative Skempton's pore pressure parameter mean?

I am reading B.M. Das' book Principles of Geotechnical Engineering, 6th edn. In the chapter about Consolidated-Undrained triaxial test it is mentioned that the range of Skempton's pore pressure ...
1 vote
33 views

### Is internal friction angle isotropic in soil?

I am studying geotechnical engineering and specifically the chapter in B.M. Das book of the same name, 6th edition. On the topic of shear forces, reference to internal friction angle, $\phi$ is made. ...
1 vote
167 views

### Relationship between inclination of failure plane and angle of internal friction in soil

I am reading Geotechnical engineering by B.M. Das, 6th edition. In the chapter on shear strength of soil this is stated: "It can be shown that $2\theta = 90 + \phi'$ " where $\theta$ is the ...
40 views

### Prove a formula for void ratio that depends on saturated, dry and water unite weights

I don't know where else to post this. I am reading a Geotechnical engineering textbook by B.M. Das, 6th edition. Problem 3.1 is as follows: For a given soil, show that e=\frac{\gamma_{sat} - \...
19 views

### where should center of gravity of cargo for the entire structure to be JUST stable?

My work: My answer for 1 is 2.5m (floats) For 2: MG must be positive and Ym - Yg must be positive I am not sure where to go from here.
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### Testing specimens by dropping a ball on them and counting the number of drops required before the collapse. A better way?

A huge number of specimens are built. For each specimen, soil is mixed with cement (and Zeolite) with different percentages. It's intended to test, measure and compare the impact strength of the ...
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91 views

### Soil movement due to open cut excavation

When I model an open up excavation in the computer model, I found that when the surcharge applied on slope is long enough , the soil movement (downwards under the surcharge region) is lower. When I ...
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### Water flow near dam geomechanics

I have basic Geomechanics question , one of the drawing is true and the others are wrong , which one ? , explain why the others are wrong . First one wrong because the number of squares are not equal ...
1k views

### Relation of shear strength to bearing strength of soil by formula

From formulas: Shear Strength: $τ = c+ σ'\cdot sin\phi$ Bearing strength such as: $1.3 cN_c+ qN_q + 0.4B_γN_γ$ Now I know that bearing capacity decreases as the shear strength of soil decreases. ...
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1 vote
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### Civil Engineering - Detailing of free draining backfill and modelling of hydrostatic pressure in retaining walls

It is considered best practise to specify free draining backfill material (eg gravel) to be placed immediately behind a retaining wall. Supposedly, this alleviates hydrostatic pressure on the wall, ...
88 views

### Low pile capacity during pile driving

When driving piles, the resistance from the soil is constantly measured. What happens when the expected resistance values from the soil are not obtained? For a single pile or for multiple piles? What ...
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1 vote
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### When settlement criteria of a foundation is satisfied, bearing criteria is also automatically satisfied?

We design the foundations to settlement criteria than bearing correct? Because settlement criteria is stricter? I mean, can there be an example where the settlement criteria is satisfied but bearing ...
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1 vote
311 views

### Effect of overburden pressure on the skin friction pile capacity

In a given soil, the lateral effect of overburden pressure is constant with depth, as in $p=qk$, where: $p$: lateral pressure effect, $q$: overburden pressure $k$: soil lateral pressure coefficient. ...
• 457
569 views

### Drained and undrained shear strength of clay correlated?

When we measure the undrained strength of clay via CPT or triaxial test for instance, is there a way to correlate this to drained strength? How? I ask because measuring drained strength takes very ...
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1 vote
125 views

### Does Eurocode allow use of Robertson chart to determine soil type based on CPT results?

It seems that use of the Robertson charts (Robertson, P.K. [1990] " Soil Classification using the cone penetration test" Canadian Geotechnical Journal 27(1), 141-8) to classify soil type based on CPT ...
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### How much does the weight of urban structures (buildings) affect the compaction (permeability, porosity, density) of alluvial sediments below a city?

Original Question was here. I live in Van, Turkey. Van City is situated on an alluvial plain beside Lake Van. General geological structure of the area can be seen on pages 43-44 in this conference ...
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### Modelling Soil in a Scale Model

I'm building a scale model for a proposed construction project. Is it possible to simulate foundations operating in soil in a scale model? What do people typically use?
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### Difference between Allowable Bearing capacity Service and Ultimate?

When we calculate the dimension of a foundation we always use the allowable SERVICE bearing capacity (lets call it qs) and all the necessary checks are based on this value qs. My question is why does ...
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41 views

### What is the effect of ageing on preconsolidation pressure?

Preconsolidation pressure is the maximum effective vertical overburden stress that a particular soil sample has sustained in the past. How far in the past does the soil remember its loading/the ...
81 views

### Soil mechanics-Geotechnical engineering [closed]

Which is more economical to improve or change the soil that is used to build a structure? my answer is that it depends on each case, but I would like to get more information, or where to search about ...
1 vote
433 views

### Liquid Limit of Soil through Atterberg Tests

My lab is evaluating the liquid, plastic, and shrinkage limits of some soil samples and we are following this video provided by the Missouri University of Science and Technology. The video indicates ...
625 views

### Is it possible for a silt soil to be compacted hard as a rock?

I had been told that a silt soil, when professionally compacted (from all the laboratory essays to the compaction with a vibratory roller), ends hard as a rock, and when hit with a metal bar it makes ...
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13k views

### Retaining Wall: Saturated Soil & Hydrostatic Pressure

I understand that Hydrostatic pressure and Soil pressure exist concurrently. I'm curious how these separate loads interact with each other. Full disclaimer: I am not an engineer nor do I pretend to ...
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1 vote
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### What is the physical meaning of Cumulative Passing% in Grain Size distribution?

When preforming a grain size distribution on a sample of Soil using Mechanical Sieves (e.g. Sieve #4 and sieve #10 and sieve #40) one of the necessary calculation need for drawing the particle size ...
78 views

### Penetration rate for miniature cone

Is there any recommended/suggested/required penetration rate for a miniature cone penetrometer? A 20mm/s is for a standard size of cone penetrometer, what about for miniature one?
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Anyone know how to solve for the OMC and MDD using mathematical solution? The book says its OMC is 13% and MDD of 2020. I tried using $a+bx+cx^3$ and getting its maxima but its far from 13%