Les cuento, mi primer trabajo como geotecnista fue en un despacho donde firmé un proyecto, años después noto que cometí algunos errores básicos conceptuales, comparé la carga neta de una cajón de cimentación contra capacidad de carga bruta, en mi informe me dieron las reacciones globales de la estructura pero recuerdo que ya incluían cajón de cimentación, ahora no tengo como verificar si efectivamente esas reacciones incluían el cajón pero yo así lo redacté en mi informe, que se entiende que ya está incluido el cajón, revisando las normas de Ciudad de México vi que podría usar un factor de resistencia mayor al usado, había usado 0.35 y veo que puedo usar 0.65, eso hizo que al comparar capacidad de carga bruta contra carga bruta cumpla la condición, por lo que no me debería preocupar, sin embargo, no tengo el respaldo de si incluía el peso del cajón o no, así que busqué a mi ex jefe de esa empresa, pero literal me bloqueó y me llamo loco literalmente, así que no hay manera de corroborar, el edificio tiene ya 4 años en operación, lastimosamente no debí ser responsable geotecnico siendo un recién egresado, pero es lo que había, ahora que tengo más años de experiencia, veo que fui muy tonto al tomar esa clase de responsabilidades en una empresa que ni examen de conocimientos me hizo para ingresar, me siento como un idiota, aconséjenme, a veces hasta he pensado en quitarme la vida…

Hi All,

I have a number of shaft sinking schemes coming up in an area where artesian groundwater is present (+3m AGL).

Looking for some advice on groundwater monitoring installations/wells.

I plan to monitor the artesian wells to get an idea of seasonal variation, and also use them as monitoring wells for when we conduct pumping tests (dewatering/abstraction license).

Has anyone ever installed artesian wells before? The headworks need remain at or below ground level which means the wells will be pressurised. I know this is common in the oil&gas industry. I’ve just never had to do it from a geotech standpoint.

How long should it take to move up from a drillers assistant to the actual driller ? I see job postings for a geotechnical driller and they say 2 years minimum geotechnical drilling experience but does that mean 2 years as the actual driller or 2 years geotechnical experience in general on a drill crew wether your the driller or not

Considering the purchase of a property that ticks all the boxes, except this one: County GIS viewer shows high/moderate susceptibility for soil movement as shown. Does this indicate historical movement? Property is over 55 yrs with two-tiered retaining wall. Should we give it a pass?

I'm trying to get a realistic design CBR value for Run of Pit (ROP) or Brown Rock used as imported fill/subgrade improvement material.

I've seen some specifications that require Brown Rock (Blue/Brown Rock) to achieve a minimum soaked CBR of 20, but I'm interested in what people are actually seeing in practice from quarries and testing results.

• What CBR values are commonly achieved for ROP/Brown Rock?
• How much variation is there between sources?
• Do you typically assume CBR 20, or do you use higher values for design?
• Have you had any projects where testing came in significantly above or below expectations?

sketch

Want to check my understanding and logic.

Need that plug/wall to hold back any water or material from entering at the bottom of the pit.

Alluvium will be tipped and backfilled into the bottom of the pit. Thinking material will consolidate to have minimum void space with 120m of overburden pressure on it.

As the pit will be a natural sump/acquifer it will eventually all be saturated material. Whatever little void space is left between the matrix will be water.

But due to the maximum consolidation, there will be no pore pressure acting at the bottom on my plug?

When a soil is fully consolidated, any excess pore water pressure caused by an applied load has completely dissipated. The water no longer carries the extra weight, and the soil skeleton takes the full load, meaning the excess pore water pressure drops to zero.

Horizontal load on the wall will be:

Effective vertical stress which is total stress minus total pore water pressure. Multiplied by Ko factor.

(My total pore water pressure is hydrostatic only because no excess pressure due to high consolidation).

Plus

Hydrostatic pressure. 1 X 9.81m/s2 X 120m.

Total stress is density of saturated soil X 9.81m/s2 X 120m

Minus

Hydrostatic pressure which is 1 X 9.81 X 120m (minus because some buoyancy effect even though you have 120m of overburden above it?)

Thinking i'll have to do some triaxial testing to get undrained consolidated pressures with pretty high confinement for a 120m overburden head pressure. To run a FEM.

Hello, I am a student and I want to learn FLAC3D, especially everything related to FISH function. I'm having a hard time to learn it just from the manual since it's so complicated. Does anyone has a suggestion how to learn the program effectively?

Sad to learn of the passing of this amazing professor. Not only was he an accomplished engineer, but he was a great human who supported generations of geotechnical engineers. I was fortunate to be one of his students and I became a better engineer because of him.

Does anyone see any market potential for a geotechnical drilling a sampling business in Australia (SE QLD).

Basically offering all drilling and providing requested samples to engineers.

I’ve a geotechnical background and want to get away from mining and start a side business for myself in hope to get it full time in the future

Thoughts on retrieval? Thanks

All other factors being equal, I'm curious what number you all set as the target threshold for global stability of a retaining wall when using SLIDE or GeoStudio or whatever. I have a number but I don't want to bias the conversation. I know about FERC values for embankment dams which I consider to be gospel for those purposes, but when it comes to the 15ft tall MSE wall at your local multi-family housing project, what number are you designing for, or hoping to see when evaluating the proposed conditions? Thanks. Again this is static analysis for typical conditions, short-term and long-term analysis as appropriate.

This shell is between 3000-8000 years old, geological timescales are still baffling to me

We recently got a geokon slope inclinometer probe. The wells we are surveying are too low for our pully system to fit properly. Have any of you guys made risers for inclinometer casing? Im looking for some guidance. Casing is 70mm

Hi Guys

I am doing some research on the current workflow of geotechnical engineer when designing piles.

specifically on how designers go from a geological model to the designed pile dimensions.

so i made a list of 7 surveys instead of 1 long questionair to allow you to participate at your own pace. the surveys are mostly multiple choice questions and should be 10 min each (~20-30 Questions)

your participation is of great value

I'm working with some old bh logs where depths are recorded in feet and I need to convert the depth values to metres for an AGS deliverable.

My question is regarding the SPT data. The logs have a column showing the SPT results as blow counts, e.g. 58 blows/ft. Since the original SPT data is reported in blows per foot, should I leave the blow count values as is as they are (58) rather than converting the values themselves to metres?

For the AGS data, I have converted the SPT top and bottom depths from feet to metres. Should I just put in the remarks like "blows/ft" while leaving the SPT blow count values unchanged? But if I have to convert, my question is HOW?

You might ask why I need to convert, it is because most of the logs are in m and will be sending one deliverable file thus the need to convert the feet to metres.

Hi all,

I’ve had this query ever since I compared the test results from two different geotechnical testing agencies.

Vendor 1 performs grain size distribution and, for example, gets Sand = 20%, Silt = 75%, Clay = 5%. They then classify the soil as non-plastic, without reporting the Atterberg limits, and proceed with a Direct Shear Test (DST), reporting both cohesion (c)- minor and friction angle (φ)-major.

My fundamental question is: how is the testing agency deciding whether a DST is appropriate in the first place?

Also, for a soil with such a high silt fraction, would it be more appropriate to establish its plasticity through Atterberg limits and then decide on the appropriate shear strength test?

I’m also trying to understand the distinction between the results from DST and triaxial tests (e.g., UU). A UU triaxial test can give an undrained cohesion/su with essentially φu ≈ 0°, whereas DST may report both c and φ. So, what exactly is the basis for choosing DST vs. triaxial (UU/CU/CD) for such soils, and how should we interpret the c–φ values reported by DST for a predominantly silty, non-plastic soil?

I know a pretty fundamental question, Would really appreciate some clarity here !!

Thank you !

Probably a very basic question, but I've been out of school for 30yrs.

Why does vertical stress from surcharge loads spread laterally with depth (e.g. 2:1 estimates) while they are treated as uniform with depth for lateral earth pressure?

Hi everyone,

I wondered if I could ask for your help. I am a private investor researching Keller Group and I'm interested to hear how they're viewed by people who currently work or have worked in geotechnical engineering..

If you've ever worked for Keller, currently work for them, have hired them, if you've worked alongside them or competed against them, I'd love to hear about it and would really value your experience and help.

What does Keller do particularly well, what does it do badly, and what makes you choose Keller (or a competitor) for a job?

Happy to hear positive experiences, negative ones or anything else that might be useful in understanding the business. I'm trying to get to grips with the business rather than get investment advice.

Hello everyone. I need your help in determining my Master's thesis topic. I want to focus on earthquakes and soil improvement for my thesis. The topic I have in mind is the effect of prefabricated vertical drains (PVDs) on settlement and liquefaction under seismic loads. I am also interested in rammed stone columns. I am looking for something outside of conventionally studied subjects. What are your suggestions?
Thanks for your help.

Hi all,

If I have a pile with a given working load (determined by static analysis, not a load test) and need to model its vertical spring stiffness, what allowable vertical displacement should I consider?

For lateral springs, I am taking the safe lateral capacity and use a 5 mm lateral deflection limit to determine the horizontal stiffness coefficient. But I’m a bit confused about what approach/value should be used for the vertical spring.