Pile - Soil Interaction During Installation in Carbonate Sand
Author
Bhattarai, Bibek
Term
4. term
Education
Publication year
2026
Submitted on
2026-11-19
Abstract
This master’s thesis investigates how particle breakage influences the drained mechanical behaviour of a crushable carbonate sand from the South China Sea and how this, in turn, affects the installation of driven piles in such deposits. The work is divided into an experimental part and a numerical part. In the experimental programme, six consolidated drained triaxial tests are performed at nominal relative densities of 30, 60 and 80 % and effective confining stresses of 200 and 500 kPa. These tests are used to analyse strength, dilatancy and stiffness, and to quantify particle breakage through sieve analyses and microscopic examination. The results indicate that peak strength is governed by dilatancy, which is suppressed at higher stress levels due to grain crushing, that the constant-volume friction angle is about 41°, and that breakage is controlled more by the initial density than by the plastic work input. In the numerical part, the laboratory findings are used to calibrate a breakage-enhanced wave equation model for pile driving. The model shows that particle breakage reduces soil resistance, mainly at the pile toe, but does not necessarily make the pile easier to drive because the crushed soil beneath the toe increases the toe quake, i.e. the elastic deformation at the toe. The thesis thus provides experimentally grounded insight into the link between particle breakage in carbonate sand and pile–soil interaction during installation, supporting more reliable assessment of bearing capacity and drivability of pile foundations in carbonate-rich offshore environments.
Denne kandidatafhandling undersøger, hvordan kornbrud påvirker den drænede mekaniske adfærd af en knuselig karbonatsand fra Det Sydkinesiske Hav, og hvordan dette igen indvirker på installationen af nedrammede pæle i sådan sand. Arbejdet er opdelt i en eksperimentel del og en numerisk del. I den eksperimentelle del udføres seks konsoliderede drænede triaxialforsøg ved nominelle relative densiteter på 30, 60 og 80 % og effektive inddæmningsspændinger på 200 og 500 kPa. Forsøgene bruges til at analysere styrke, dilatans og stivhed samt til at kvantificere kornbrud ved sigteanalyser og mikroskopiske undersøgelser. Resultaterne viser blandt andet, at toppestyrken styres af dilatans, som undertrykkes ved højere spændingsniveauer på grund af kornknusning, at den konstant-volumen friktionsvinkel er omkring 41°, og at graden af brud er mere afhængig af startdensiteten end af den plastiske arbejdsinput. I den numeriske del anvendes laboratorieresultaterne til kalibrering af en bølge-ligningsmodel for pæleramning, der er udvidet til at medtage kornbrud. Modellen viser, at kornbrud reducerer jordmodstanden, primært ved pælefoden, men ikke nødvendigvis gør pælen lettere at ramme, fordi den knuste jord under pælefoden øger toe quake, dvs. den elastiske deformation ved pælefoden. Afhandlingen bidrager dermed med eksperimentelt baseret indsigt i koblingen mellem kornbrud i karbonatsand og pæle–jord-interaktion under installation, hvilket kan forbedre vurdering af bæreevne og drivbarhed for pælefundamenter i karbonatrige offshore-områder.
[This abstract has been generated with the help of AI directly from the project full text]
Keywords