GeoCorner

Author: Rufus Bloomfield

Supervisor: Assistant Professor Lauri Uotinen

Advisor: Dr Mateusz Janiszewski

Collaborative partner: -

Abstract: 

Point clouds generated by LiDAR or photogrammetry provide a low cost, high speed, non-contact means of identifying and characterising rock mass discontinuities but have no in-built ability to model behaviour; Discrete Fracture Networks (DFNs) are a popular numerical method for analysing discontinuity behaviour and modelling fluid flow, but typically only model generic units of rock mass based on statistical parameters which are in many cases difficult to acquire with manual measurement. By connecting existing open-source software and methods while expanding their capabilities, DisTunnel aims to be a simple, powerful and deeply customisable tool for modelling rock mass discontinuity geometry by converting point clouds to DFNs. To demonstrate its functionality, we present the outcomes of using DisTunnel to mesh 3 point clouds of rock exposures from the Underground Research Laboratory of Aalto (URLA), each roughly 300,000 points representing around 30 square metres of exposure. As part of this, two novel approaches for defining the aspect ratio of exposed fracture surfaces are described, applied to a dataset of 566 natural fractures from URLA, and found to have favourable properties compared to existing bounding box methods used elsewhere in the literature.

Author:  Irfan ul Haque

Thesis supervisor:  Mr. Sanandam Bordoloi, Assistant Professor

Thesis advisor(s):  Mr. Muhammad Hanafi, Postdoctoral Researcher

Abstract
Sulphide-bearing clay is commonly excavated during construction and infrastructure
works in northern Finland. Its disposal is challenging because exposure to air
and moisture cause sulphide oxidation, acid generation, and mobilisation of harmful
elements. This thesis aimed to characterise sulphide-bearing Oulu clay and to
investigate its potential for valorisation as a constituent of cold-bonded aggregates
and cementitious composites.
The clay was fine-grained and moisture-sensitive, with a specific gravity of 2.69,
clay-sized fraction of 22.7%, natural water content of 68%, liquid limit of 80.4%,
plastic limit of 30.8%, and organic content of 4.1%. Oxidation testing showed a reduction
in pH from 6.93 to 3.40 over 27 days, accompanied by an increase in electrical
conductivity from 611 to 2440 μS/cm, confirming its acidification potential.
Among the aggregate binders, CEM I provided the highest alkalinity, while CEM
IIIB produced the highest point-load strength. Carbonated aggregates without biochar
amendment reached approximately 1.6 MPa with CEM I and 1.9 MPa with
CEM III/B at 28 days. Biochar reduced aggregate density but also reduced strength;
for example, apparent density decreased from 2.66 to 2.02 g/cm³ for CEM III/B
aggregates at 40% biochar. In concrete, naturally wet clay substantially increased
the effective water-to-cement ratio and reduced 28-day compressive strength to
24.3 MPa at an effective water-to-cement ratio of 0.91. Hydrophobisation improved
performance by reducing clay water uptake and achieving similar strength: mixtures
containing 5% and 10% hydrophobized clay achieved 28-day strengths of 25.7
MPa and 24.3 MPa, respectively, exceeding the 20 MPa target selected for nonload-
bearing components. The results indicate that Oulu clay can be incorporated
into artificial aggregates and low-demand cementitious products, provided that durability,
and environmental performance are further verified.