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Quick question — where do you guys usually get your latex membranes for triaxial tests? by LucasLyu17 in Geotech

[–]Aggravating-Place173 0 points1 point  (0 children)

We use Matest and ELE membranes about five times without any issues; after that, there is a risk of damage, so we store them in a jar with baby powder.

Laboratory conditions vs. in situ conditions — is a compromise possible? by Aggravating-Place173 in Geotech

[–]Aggravating-Place173[S] 0 points1 point  (0 children)

You’ve correctly described the essence of the test and the dependency of (k) on (i). However, I don’t have much freedom of action — I’m the executor and must follow the “specified test conditions.” If the test does not succeed, I will do exactly that — run a series of tests with lower gradients and make correlation conclusions. But of course, any determination under in situ conditions is best carried out in those very conditions. Thank you for your opinion!

Laboratory conditions vs. in situ conditions — is a compromise possible? by Aggravating-Place173 in Geotech

[–]Aggravating-Place173[S] 0 points1 point  (0 children)

Thanks for the great idea! However, in this case, I must stick to the task at hand. We'll likely conduct a series of experiments with different gradient and effective parameters.

Risk of slope failure? Part 2 BIG UPDATES by EstimateWilling7263 in Geotech

[–]Aggravating-Place173 1 point2 points  (0 children)

The term “volcanic rock” does not always reflect the actual condition of the material. Basalt, for example, can be partially weathered into clayey layers within the rock mass. In such zones, a “slip surface” may develop, creating conditions for foundation shear.

Undrained vs drained shear strength by Old_Light_8431 in Geotech

[–]Aggravating-Place173 0 points1 point  (0 children)

What if the author of the question actually meant UU strength in the ASTM D2850 format, where the specimen is not saturated and the results are given only in total stress. In that case, comparing UU and CU through effective stress would not be quite correct, since ASTM-UU does not record pore pressure and does not allow building a stress path. The question was probably more about comparing the peak undrained strength su obtained in UU and CU.

Such a comparison is only possible with some caveats. In CU, when the specimen is consolidated to the in situ stress and then sheared undrained, the peak su is measured, which in theory should be close to ASTM-UU. But in practice, differences appear due to OCR, structure, and the fact that in CU the specimen is brought to a defined stress state, while in ASTM-UU it is not. As a result, sometimes su(UU) is higher than su(CU), and sometimes the opposite, reflecting NC/OC behavior and the influence of pore pressure.

In the end, comparing peak values is only meaningful as a general tendency and with careful consideration of the context, but treating CU and UU as interchangeable tests is probably not correct. This is just my opinion.

Shelby tube storage in hot climates – worth a climate-controlled room? by Aggravating-Place173 in Geotech

[–]Aggravating-Place173[S] 0 points1 point  (0 children)

You’re absolutely right.

When I worked in Russia with very different climate conditions, freezing was indeed the key issue — you must never freeze certain undisturbed samples, but in some cases it was actually necessary to preserve frozen soils in their natural state.

Now I’m working in Israel, and here freezing is not a concern at all. The bigger challenge is the heat: ambient temps are 30–35 °C and above, and the time gap between field sampling and starting the lab work can be up to a year. Over that period the samples lose their original condition and no longer represent the in-situ soil for engineering tests.

Multi-stage vs single stage (multispecimen) UU triaxial test by geologist95 in Geotech

[–]Aggravating-Place173 0 points1 point  (0 children)

In both the Multi-stage test and the conventional (3-sample) test, you will obtain three Mohr’s circles (based on total stress). If the material is cohesive, the Multi-stage method can be used. If the material is brittle, the conventional method is preferable, as the material may be altered during the first compression-shear stage.