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International Journal of Geoengineering Case Histories news
16 Aug 2021
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ARGO-E GROUP news
19 Aug 2021
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Abdelwahab TAHSIN, FICE, PMP, VMA news
07 Jul 2021
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ISSMGE ISSMGE Virtual University
22 Jul 2021
Watch Lecture on ISSMGE Virtual University Solving boundary value problems requires implementation of sufficiently robust constitutive models. Most models try to incorporate a gre...
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Geoengineer.org news
02 Jul 2021
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GeoWorld Administrator news
07 Jun 2021
he directory is published with the support of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). This is the seventh year for the Geotechnical Business Directory, the most comprehensive directory in the geotechnical engineering field! The 2021 index has grown significantly since last year and includes 23,000+ members, and 1,000+ geo-companies and geo-organizations from a total of 157 countries.
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Bentley Systems news
09 Jul 2021
Bentley Systems, Incorporated (Nasdaq: BSY), the infrastructure engineering software company, today announced that its Seequent business unit has acquired Danish company Aarhus GeoSoftware, a developer of geophysical software. The acquisition extends Seequents solutions for operational ground water management, and for sustainability projects involving exploration, contaminants, and infrastructure resilience.
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Adda Athanasopoulos-Zekkos ASCE
06 Aug 2021
Check out the new ASCE Special Publication on the 2020 Edenville and Sanford Dam failures in Michigan. The report is available by ASCE ...
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ISSMGE ISSMGE Virtual University
13 Aug 2021
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HARSHITHA A M news
28 Jul 2021
May I know how does the stress distribution varies with the change in the horizontal distance in the presence of voids and when the geogrid reinforcement is provided.The soil taken in highly compressi...
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Adda Athanasopoulos-Zekkos GEER
06 Aug 2021
Our GEER report on the 2020 M6.4 Petrinja earthquake was just published. Great collaboration among many professionals!
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ISSMGE ISSMGE Virtual University
22 Jul 2021
Watch Lecture on ISSMGE Virtual University This presentation focuses on numerical simulations of the thermal, thermo-mechanical, and thermo-hydro-mechanical response of energy pil...
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ISSMGE ISSMGE Time Capsule
23 Jul 2021
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Shakil Mahtab news
21 Jun 2021
As traditional numerical analysis dose not mimic materials bonding attributes hence how important is to model geo materials explicitly...isn't it more practical and reliable?
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Dimitrios Zekkos news
16 Aug 2021
I have the immense pleasure to congratulate Hao Zhou for completing his PhD thesis on Vision-Based Control of Unmanned Aerial Vehicles for #Automated Structural Monitoring and #Geo-Structural Analysis...
Read MoreIt is a general practice to carryout Point load test for 2-3 specimens retreived from Pile bores and convert to UCS and evaluate the socketing depths with other criterias, such as CR/RQD of adjacent boreholes, sample sizes, angularity/shape of samples, weathering conditions, rock condition and depths of adjacent piles etc. However as per the ASTM D 5731 to obtain accurate PLI values for lump samples at least 20 specimens shall be tested for a sample, and which is not possible/practicle with samples from bored piles. However it is understood testing 2-3 specimens are carried internationally and an accepted criteria and since it is not the sole parameter which determines the socketing the accurancy of the test results are not required to a manner it is requested to carry out as per ASTM D 5731.
However I would like to know from any expert who dealt in this area, the reliability of UCS recieved from PLI test if we test only 1 specimen, 2 specimen or 3 specimen.
Asoka,
Please note that the purpose of testing at least 20 samples is to be able to estimate the strength value using any available statistical tool. You cannot get a meaningful result when you try to determine the mean value or the standard deviation using results from only three samples. If you have a very limited samples to test, the best practice is to perform both PLI and UCS on a few samples and then develop a graph for the two tests (i.e., UCS vs PLI graph). Once this graph is plotted (hopefully, with a reasonable coefficient of correlation), you can easily determine corresponding UCS values of any PLI tests from the equation of the graph going forward. I have attached a plot of UCS versus PLI on a project that l was actively involved during 2004-2005 timeframe.
Dear GeoWorld community
I want to create a 3D Finite Element model in PLAXIS3D based on a fairly detailed UAV mapping of a slope. To reduce the size of the file, the point cloud has already been sub-sampled to a 1m spacing (~20,000 points). Is there an efficient way to import the point cloud into PLAXIS3D and subsequently create a numerically stable 3D FE model?
Best Regards,
Sally Simpson
Hi Sally
Interesting question.
You can import the UAV map via the point cloud functionality in PLAXIS 3D. See e.g. this video (second half):
https://communities.bentley.com/products/geotech-analysis/w/plaxis-soilvision-wiki/45842/creating-a-model-with-ifc-and-point-cloud-import
If this does not work, please reach out via https://apps.bentley.com/srmanager/ProductSupport where our Technical Experts are ready to help you out.
Kind regards,
Micha van der Sloot
Bentley Systems, Geotechnical Analysis (PLAXIS)
Hi,
I am having difficulties modeling the seepage in an earth dam enhanced with a cut off wall using Plaxis 2D. The cut off wall is made of plastic concrete and was introduced later as part of a maintenance procedure in order to prevent any potential leakage from the resevoir. The plastic concrete was defined using the soft soil creep model as a drained impermeable material. Tutorials nr.12 and nr.14 in addition to a webinar on running a groundwater analysis gave an overview of the GWF BC's and of how to use time dependent flow functions in a fully coupled flow deformation analysis and how to run a GWF analysis. I've tried to combine all these tutorials by the modeling process to obtain the most optimum seepage / flow line but still haven't succeeded. The results of the analysis show that the cut off wall doesn't influence the seepage, which indicates an error in the input data or in the definiiton of the GWF BC's.
Could anyone please help me solving this problem.
Thank you all in advance.
Hi
If you model the concrete using the soft soil creep model, and you set it to behave as a Drained material, the permeability value will still control its behavior. Or did you model it as a non-porous material?
When you want to model a screen around this concrete cutoff, you can also add interface elements around the concrete wall, and make sure that these are activated for the flow calculation. They will appear in orange in the Flow Conditions mode (PLAXIS 2D CONNECT Edition V20 and later), so then it is easy to check if these are activated.
I would advise checking the results, especially the groundwater flow arrows, and hydraulic gradients to see if the water will flow around the cut-off wall. You can see these via Stresses > Groundwater flow > |q| in the PLAXIS Output program.
For detailed answers specific to your model, and that allows us to investigate this model, please raise a Service Request here: https://apps.bentley.com/srmanager/ProductSupport
By the way, on July 27, we also host a live Q&A, the answer hours related to water conditions.
Another question: any reason you are using the Soft Soil Creep model for the concrete? The Concrete model in PLAXIS also has time-dependent behavior for creep.
Kind regards,
Micha van der Sloot
PLAXIS | Bentley Systems, Inc, Geotechnical Analysis
Hi,
thank you very much for your kindly response.
The cutt of wall was modelled as a soil element with low permeabilty and the drainage type was set to drained. The reason behind using the soft soil creep model to define the cut off wall material is because I am relying on a study, which has studied the creep behaviour of plastic concrete using the soft soil creep model. In addition, the available input prameters that I have are only valid for the SSC model.
I've never known that the creep behaviour of concrete could be included in plaxis 2d, thank you for the remark. But I have an additional question for you: isn't plastic concrete by definition somewhere between concrete and soil element? Plastic concrete differs from normal concrete in composition and in compressive strength, wheres the compressive strength of the plastic concrete is almost 1/10 of the compressive strength of normal concrete, not to mention that PC is more ductile. Is it suitable to model PC as normal concrete or as soil? Which one is better in your opinion?
Introducing interfaces into the model didn't change the seepage path inside the dam that much. Seepage resulted from a flow only analysis was more realistic than that resulted from a fully coupled flow deformation analysis. Unfortunately the stresses obtained from flow only analysis aren't reliabale, are they? Isn't a fully coupled analysis supposed to deliver the same seepage patterns resulted from a flow only analysis? Is there anyway to run a plastic analysis following a flow only analysis?
I've already registered for the session tomorrow and I am looking forward to it. Is it possible to present a small example of a dam with a cut off wall during the session?
Best regards
Ahmad Jazzar
I have a question on how to determine the coefficient of secondary compression and the intital volumetric strain rate as part of the input parameters of the Sekiguchi-Ohta viscid model. The Material Models Manual of Plaxis 2D suggests using a secondary compression index as an alternative to the above mentioned input parameters without any further informations on how to specifiy it. Unfortunately I haven't found a lot in the literature about this subject. The second question is wether it is possible or not to derive the input parameters of the Sekugichi-Ohro viscid model out of the input data set of the soft soil creep model using the soil test tool by excuting back calculations?
Thank you all in advace.
Greetings
Bentley Systems PLAXIS
13 Aug 2021
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Bentley Systems Reality Modeling
13 Aug 2021
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Fields: Civil - Geotechnical , Civil - Environmental
Location: Wisconsin, United States
Field: Civil - Geotechnical
Location: California, United States