Source: Scott Roberts Memories from 2007 back in Durban, building a 2010 World Cup Stadium; we hit a problem with the diaphragm wall excavation, when the grabber got stuck in the bedrock about -20m down. So we sent commercial divers down through the bentonite slurry to fix a new steel cable to the grabber so we could retrieve it and keep the project going. Those boys were hardcore.
Demir et. al. 2024 — Nordhavnstunnel.pdf
During 2019 Plaxis User Meeting in İstanbul, I have presented a detailed discussion on Hardening Soil Model. The presentation was really welcomed by the audience and in fact, later on, I have been invited to two other companies for the same presentation. This short post will be a summary of that presentation. Hardening Soil model (will be called HS from now on) was presented in an excellent conference for 10th year of Plaxis in a paper called The hardening soil model: Formulation and Verification by Schanz, Vermeer and Bonnier. However, HS is tightly bonded to previous studies on the literature such as Lade, Tatsuoka and Ishihara, Cam-Clay model, Kondner and Zelasko, Jardine, Duncan and Chang, Al Tabbaa, Simson et. al. ...
I have just published a new tool and this post will detail the methods that are being used in this tool. What it does: Performs Hoek-Brown analyses for rock and recommends additional parameters based on the inputs. https://berkdemir-bd-hoek-brown-bd-hoek-brown-vsh6i6.streamlit.app/ Theory Introduction The Hoek-Brown material model is the most widely used rock mechanic model due to its simplicity and ease-of-use in continuum based numerical models such as finite element or finite difference models. Hoek-Brown model is published in Hoek & Brown (1980) and after that, it is constantly updated. Latest update was published in 2019. ...
Introduction By now, everything should have been settled about modulus of subgrade reaction. We all know some typical statements about it: It depends on the soil properties It depends on the foundation size It depends on loading type, temperature, bitcoin prices and others. However, let’s think about a weathered rock with E=500 MPa and a foundation to be built on top of this rock with 20 x 50 m dimensions. You can say it depends on many factors as much as you like, everybody has a rough idea already: 100,000 kN/m3. So, if you are a fancy engineer and dare to make some calculations, you can find much lower values. Will they believe you or will they think that you are being too conservative (if lowering the subgrade reaction means being conservative)? Let’s start with simple terms. The equation that everybody knows and nobody wants to use: $$ K=\frac{q}{s} $$ So, the subgrade reaction is equal to a spring stiffness distributed under the foundation. If you divide the pressure by the settlement, you will find the subgrade reaction, amount of deformation for unit pressure. If we think about how we calculate settlement (how it depends on many factors), we can see actually how complex this modulus is. ...
A new paper from Tatone et. al. is published here. Using the data of the authors, following violin graph is drawn to estimate Modulus Ratio (MR = E / UCS) of the different rocks. Update: Aly Abdelaziz has proposed an update on the code and graph. Thanks to him, it looks better now. Code and data are in the Github Gist. # Data from Tatone, B. S., Abdelaziz, A., & Grasselli, G. (2022). Novel Mechanical Classification Method of Rock Based on the Uniaxial Compressive Strength and Brazilian Disc Strength. Rock Mechanics and Rock Engineering, 1-5. import pandas as pd import seaborn as sns # Rock Category rock_type = {"Sedimentary": ["SL", "SSh", "SS", "SC"], "Metamorphic": ["MG", "MS", "MQ", "MM"], "Igneous": ["IG", "IF", "ID"]} ordered_box_list = [] for i, v in rock_type.items(): ordered_box_list += v df = pd.read_csv("data.csv") df = df[df.E != "-"] df = df.astype({"E": float, "UCS": float}) df["MR"] = df["E"] / df["UCS"] * 1000 sns.set(rc={"figure.figsize": (20, 8.27), "figure.dpi": 300}) ax = sns.violinplot(x="Type", y="MR", data=df, order=ordered_box_list) ax.set_ylim(0) The data.csv file can be saved from here or from Gist. [[Notion/Quick Note/BDEM (1)/Blog Posts/_assets/data.csv]]
If you will use Hoek-Brown in your Python code, you may want to recommend some constants based on rock type. There is a widely used table in literature by Hoek and others that we use to select Modulus Ratio and material constant (mi) in the absence of high quality laboratory tests. I have done the manual labour, don’t write it all again. A dictionary called RockDict is given in the following Gist. Rock types are given as keys of dict and a sub-dictionary with: ...