School of Civil Engineering

Projects in geotechnical engineering

Project 1. Quantifying the water balance in cover systems of mine rock waste - analysis of long-term TDR measurements

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

Every structure built of earth is exposed to the atmosphere with the consequence that the water content within the structure changes with changing weather and seasonal condition. Water infiltrates into the earth body leading to an increase of water content. If the precipitation event is to intense surface runoff occurs. Water seepage and evaporation reduce the water content. The aim of the project is to quantify these water balance processes by analysing moisture measurements conducted using Time Domain Reflectometry.

 

Project 2. Highly compacted bentonite plugs for abandoning wells – Study of the mechanical behaviour through laboratory tests

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Project 3. Highly compacted bentonite plugs for abandoning wells – Processes involved in the dislodgment of plugs and the breakthrough in tubes

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

The projects aim to deliver a novel, more reliable, lower cost plugging and abandonment (P&A) technology for the coal seam gas (CSG) industry partners in their obligations to decommission wells. Wells and bores have historically been plugged with cement. This is expensive and the cement can potentially shrink and crack leading to possible methane migration or cross-flow between aquifers. UQ is developing bentonite ‘plugs’ that swell when they come into contact with water within the well and provide better sealing. To date, this lower cost approach is designed for use in ‘idealised’ cased CSG wells with no integrity problems. Additional research to develop optimised material compositions and new plug-geometries for a wider range of older, legacy wells from coal, CSG and agricultural industries has started recently. Laboratory testing will determine detailed composition and chemistry of raw bentonites from Queensland mines; analytical approaches will test pre and post-hydration properties of bentonite plugs (e.g. swelling pressures, mechanical and chemical properties). Experiments will add understanding of the changes within the plugs as they swell in well-bore water and help predict the long-term behaviour as required for industrial use.

 

Project 4. Quantifying engineering properties of soft soils through electromagnetic measurements

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Project 5. Dewatering of soft soils by means of controlled desiccation

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

Saturated dredged materials generated from port and harbor areas demand a way for ecofriendly and economical disposal as well as in place strength improvisation. As such, fluidisation of soft porous materials had resulted catastrophic consequences such as failure of dams, instability of slopes and other environmental challenges. During strength improvisation of soft soils to mitigate the above mentioned disasters, the interactions of hydro mechanical processes are yet not fully understood. In view of the above, to capture the transitional behaviour of suspended sludge to soil like material and through direct measurements as well as non-invasive electromagnetic methods (Frequency Domain and Time Domain Reflectometry), the proposed research aims to investigate the changes in mechanical, hydraulic and rheological properties of soft soils and reference geo-materials subjected to controlled desiccation. Scope of the work also encompasses development of a novel method for improvement of soft soils through ventilated drains and alteration of pore fluid chemistry.

 

Project 6. Quantifying the process of contact erosion – analysis of porosity changes during experimental investigations

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

Contact erosion is one of the challenges a geotechnical engineer has to face in the presence of flowing water in both structures like embankment dams, but also in naturally grown soils. Many criteria were developed to predetermine the onset of erosion, but the description of the progress of erosion attracted little attention. In order to close this gap in knowledge, a new experimental setup was developed which makes it possible to quantify and analyse the porosity changes during an erosion process. The results of these measurements will help to improve the understanding of the mechanisms that induce and maintain the process of contact erosion.

 

Project 7. Quantifying density changes for moisture content variation during mechanical tests of pavement materials

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

Soil water content and dry density of unbound granular pavement materials are important properties for compaction control which can exert a great influence on pavement performance. Time domain reflectometry (TDR) uses rod probe sensors which provide valuable information of moisture content. However, with changing moisture content changes in density might be accelerated under cyclic traffic loading. This project will introduce new calibration functions based on TDR measurements done in the laboratory for soil samples of both constant moisture content with different density and different moisture content at constant density. Wheel trafficking (WT) test, mechanical test of pavement would be conducted in the following as well to correlate the surface deformation of road for the variation of moisture and density of road materials. These calibration functions can be used to measure long term pavement performance, for example, monitoring the influence of rutting of roads.

 

Project 8. Hydraulic fracturing of artificial rock materials – influence of different types of fluids on the fracturing process

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

Hydraulic fracturing is the artificial creation of fractures to increase the permeability and connectivity of fracture systems by applying an excess pressure in the water-phase. The process of hydraulic fracturing depends on the mechanic parameters of the geo-material, the ambient hydraulic and stress conditions, the characteristics of the existing fracture system and the properties of the fracturing fluid. For systematically investigating the process of hydraulic fracturing, artificial rock-like materials have been developed at the School of Civil Engineering. An in-house developed set-up allows the implementation of hydraulic fracturing test. The aim of the project is to systematically vary different types of liquids to investigate the influence of the fluid properties on the process of hydraulic fracturing.

 

Project 9. A study of dynamic multiphase flow in granular porous media

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

The soil water retention curve (SWRC) is the most important characteristic of a partly water-filled porous medium for predicting its hydro-mechanical behaviour. However, the concept of SWRC only works on steady state or static condition. This might lead to underestimation of soil suction in drainage but overestimation of soil suction under intensive rainfall and flooding. Under transient flow condition, the processes taking place are far off from equilibrium condition and cannot be described using the theory of multiphase flow seepage in porous media. The main shortcoming in existing frameworks is the lack of knowledge in the evolution of the SWRC under dynamic conditions. Soil column tests are available to experimentally investigate the dynamic SWRCs, and numerical methods like the Lattice Boltzmann Method can be used to gain further insight into the underlying processes. The aim of project is to use advanced numerical and / or experimental techniques to investigate the SWRC concept under dynamic and transient flow conditions.

 

Project 10. Characterisation of flow conditions in heterogeneous granular structures using Particle Imaging Velocimetry

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

The flow of water through porous media undergoes changes in flow conditions governed by the applied head difference. If the local flow velocities within the porous medium are small enough, then there is on the micro-scale a linear relationship between water flow and applied hydraulic gradient which is considered as laminar flow. With increasing flow velocities, the flow condition becomes increasingly non-linear indicating partly turbulent flow conditions. Latest investigations at the School of Civil Engineering with mono-disperse packings (created by particles of one size) show that on the micro-scale flow conditions already change in the laminar flow range. The aim of the project is to investigate the flow conditions for poly-disperse packings. A set-up for investigating micro-scale flow using Particle Imaging Velocimetry and transparent soil is available for this study.

 

Project 11. Quantifying the effect of mud farming using amphirols

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

Amphirols are used to accelerate hindered sedimentation of soft materials in evaporation or storage ponds. The implementation of amphirols in the management of these kinds of facilities is also called mud farming. As a result, a top soil layer of up to 1.5 m depth is created with increased density and this improved shear strength. As a consequence the operation of these facilities will allow the application of surcharge at a much earlier stage than without the application of amphirols. The processes involved in the improvement of the soil conditions associated with the application of amphirols is not fully understood yet. The aim of the project is to conduct laboratory experiments and to use field data to improve the understanding of the soil improvement created by mud farming.

 

Project 12. Consolidation of dredged materials – Analysis of in situ observations

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

Soft dredged soils are deposited in so-called evaporation ponds for dewatering and for gaining enough strength to be further used or consolidated using surcharge supported by installed wick drains. The process of consolidation with these soft materials is extremely time-consuming as the material undergoes large deformation in form of compaction accompanied by flow of water out of the pore structure. At the Port of Brisbane, consolidation of dredged soils in paddocks has been observed over many years. In the frame of the project, these in situ observations are analysed using commercial numerical tools.

 

Project 13. Improvement of water management to minimise settlements in the Mekong Delta

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

The extensive use of groundwater leads to severe settlements in the Mekong Delta. This leads to the critical situation that the elevation of large areas in the Mekong Delta are already now below the current sea level which will become even more severe against the background of the forecasted sea level rise. The proposed project aims at investigating possibilities to optimise water extraction with the aim to minimise settlements. Based on simple laboratory experiments, coupled numerical calculations using a sophisticated constitutive relationship of the soil allowing the considerations of elastic and permanent plastic deformations will be used to provide answers to this question.

 

Project 14. Avoiding damages of houses build on expansive soils

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

Domestic buildings in Queensland are frequently damaged by volume changes in the foundation caused by moisture differences in the expansive soil beneath and around the house. Also vegetation can cause similar conditions leading to moisture migration with consequential volume changes. The project aims at investigating the possibilities to minimise moisture migration by constructive elements in the ground. Expensive soils are characterised and model investigations are conducted in the laboratories of the School of Civil Engineering.

 

Project 15. Developing tools and strategies for engineering education in future

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

The education landscape in universities worldwide will change dramatically in the coming years. Students will increasingly study remotely and physical attendance of events at universities will dramatically decrease. Strategies for improving the engineering education are required, which are specifically designed for the future scenarios. The project aims to develop new tools for the provision of education which are based on new media technologies.

 

Project 16. Analysing the performance of roads

Supervisor:             Assoc. Prof. Alexander Scheuermann a.scheuermann@uq.edu.au

The performance of roads depends on many factors, which change with time. To be mentioned are the traffic load (number, weight and velocity of vehicles), weather condition (radiation, precipitation) and ground condition (soft soils). Quality control and maintenance of most roads within Brisbane fall in the responsibility of the Brisbane City Council. Regular inspections of roads are conducted by the Brisbane City Council to determine their structural condition and mechanical behaviour. These data have been collected over many years and are available for further analysis. For example, for some streets which were inundated in 2011, mechanical tests have been conducted immediately after the flood and have been tested several times since. Cores and bores through the pavement provide an overview of the ground condition. Based on repeated mechanical tests seasonal effects can be investigated. The project or thesis will deal with investigating and analysing these data to improve understanding of the temporal evolution of road condition and for optimising maintenance.