Unsaturated Soils Mechanics for Engineering Practice (UnsatPractice)

Lead Research Organisation: Durham University
Department Name: Engineering

Abstract

This partnership programme involves collaboration between Durham University UK and five universities in South Africa (the University of Pretoria, the Central University of Technology, Free State, the University of Kwazulu Natal, the University of Cape Town and Stellenbosch University) on a project entitled "Unsaturated Soils Mechanics for Engineering Practice (UnsatPractice)". The unsaturated characteristics of soils give rise to many geotechnical problems in the UK and in South Africa including collapse of foundations due to inadequate bearing capacity, structural damage due to excessive ground heave, sinkhole formation, slope instability both in terms of natural slopes and man-made embankments, as well as road and railway formation failure. The network comprises 13 academic staff and will train 20 PhD students. The research activities within the network are divided into three strands: laboratory and in-situ testing of unsaturated soils, development of numerical models and applications to engineering problems. The network partners will generate significant follow-on projects by seeking new research funding from national and international research councils and agencies and will establishing formal long-term sandwich PhD programmes before the end the award period.

Planned Impact

Expansive and collapsible soils are particularly sensitive to soil moisture changes. As the water content of an expansive soil increases during the wet season, the soil swells causing surface heave. During the dry season, shrinkage occurs producing settlements. Collapsible soils are characterised by large inter-particle voids, supported either by suctions in the pore-water, by cemented bonds between particles or by clay "bridges" between particles (that are themselves supported by suctions). If the soil is wetted, the suctions reduce and/or the cementing is dissolved or removed and the soil "collapses" causing a sudden reduction in volume resulting in surface settlements. This seasonal shrink/swell cycle can cause significant damage to buildings directly founded on these soils. This seasonal shrink/swell cycle can cause significant damage to buildings directly founded on these soils. The costs of damage due to shrink/swell movements on clay soils have resulted in economic losses estimated at over £1.6 billion in the UK during drought years in the 1990s. Similar figures are evident from France where losses have been as high as £2.7 billion in a single year. In China, losses due to land subsidence in Shanghai are estimated to be about £10 billion over a decade with £0.3 billion a year in losses in three other cities. Of relevance to this proposal is the fact that collapsible soils cover 67% of the total area of South Africa and their presence has an impact on most infrastructure development.

The network will enhance the ability of the partners to respond to the needs of both the domestic and international construction industry to evaluate optimal foundation and pavement designs in unsaturated soils. Therefore, the combined research will reduce potential damage to properties and infrastructures. The network will enhance significantly the mobility and international visibility of each of the partners involved. It will also provide a legacy of well-trained UK anuth African experts equipped to solve the engineering challenges of infrastructures in unsaturated soils.

Publications

10 25 50
 
Description Research on the development of sinkhole collapse in unsaturated soils is a key topic in this network and a key research activity in both Durham University and the South African partners universities. A one-day workshop was held on 8 Dec 2016 in Pretoria, attended by academics from the University of Pretoria, engineers and engineering geologists from industry which included representatives from the Cities of Tshwane and Ekurhuleni and the South African National Department of Public works. The workshop comprised a number of technical presentations featuring recent work about development on sinkhole in which the leak from water services is the triggering mechanisms. A number of deficiencies regarding the enforcement of legislation governing the development and abstraction of water were identified. Some of these are associated with poor performance of regulators. The recommendations were adopted by the Engineering Council of South Africa and the Minister of Public Work was informed of the dangers if the required standards are not enforced.
First Year Of Impact 2016
Sector Construction,Transport
Impact Types Societal

 
Description Training for researchers and practitioners in South Africa on computational tools in geotechnical engineering
Geographic Reach Africa 
Policy Influence Type Influenced training of practitioners or researchers
 
Description Using unsaturated soil mechanics framework to predict sinkhole collapse
Geographic Reach Africa 
Policy Influence Type Implementation circular/rapid advice/letter to e.g. Ministry of Health
Impact A one-day workshop was held on 8 December 2016 in Pretoria, South Africa, attended by academics from the University of Pretoria, engineers and engineering geologists from industry active on development on dolomite land which included representatives from the Cities of Tshwane and Ekurhuleni and the SA National Department of Public works. The workshop comprised a number of technical presentations featuring recent work about development on dolomite land. A number of deficiencies regarding the enforcement of legislation governing development of, and abstraction of water from dolomite land were identified. Some of these are associated with poor performance of regulators. The group drafted a letter to the Minister of Public Work in South Africa to inform of the dangers if the required standards are not enforced.
 
Description Developing a risk mitigation strategy for sinkhole collapse in South Africa
Amount £5,000 (GBP)
Organisation Durham University 
Department Durham University ESRC Impact Acceleration Account
Sector Academic/University
Country United Kingdom
Start 09/2016 
End 12/2016
 
Description Cultural, Educational and Scientific Collaboration 
Organisation Central University of Technology, Free State
Country South Africa 
Sector Academic/University 
PI Contribution We have managed to convenience the senior management in Durham and partner universities to sign a collaboration agreement.
Collaborator Contribution This agreement facilitates the future collaboration between partner universities and Durham University. Partners universities have waived bench fees for visiting academic from Durham. They facilitate the managements of the training events delivered by researchers from Durham.
Impact This agreement facilitates the exchange of researchers and academic staff in Science faculties in the partners' universities. The bench fees were waived for visiting academics.
Start Year 2016
 
Description Cultural, Educational and Scientific Collaboration 
Organisation University of Cape Town
Country South Africa 
Sector Academic/University 
PI Contribution We have managed to convenience the senior management in Durham and partner universities to sign a collaboration agreement.
Collaborator Contribution This agreement facilitates the future collaboration between partner universities and Durham University. Partners universities have waived bench fees for visiting academic from Durham. They facilitate the managements of the training events delivered by researchers from Durham.
Impact This agreement facilitates the exchange of researchers and academic staff in Science faculties in the partners' universities. The bench fees were waived for visiting academics.
Start Year 2016
 
Description Cultural, Educational and Scientific Collaboration 
Organisation University of Johannesburg
Country South Africa 
Sector Academic/University 
PI Contribution We have managed to convenience the senior management in Durham and partner universities to sign a collaboration agreement.
Collaborator Contribution This agreement facilitates the future collaboration between partner universities and Durham University. Partners universities have waived bench fees for visiting academic from Durham. They facilitate the managements of the training events delivered by researchers from Durham.
Impact This agreement facilitates the exchange of researchers and academic staff in Science faculties in the partners' universities. The bench fees were waived for visiting academics.
Start Year 2016
 
Description Cultural, Educational and Scientific Collaboration 
Organisation University of Pretoria
Country South Africa 
Sector Academic/University 
PI Contribution We have managed to convenience the senior management in Durham and partner universities to sign a collaboration agreement.
Collaborator Contribution This agreement facilitates the future collaboration between partner universities and Durham University. Partners universities have waived bench fees for visiting academic from Durham. They facilitate the managements of the training events delivered by researchers from Durham.
Impact This agreement facilitates the exchange of researchers and academic staff in Science faculties in the partners' universities. The bench fees were waived for visiting academics.
Start Year 2016
 
Description Cultural, Educational and Scientific Collaboration 
Organisation University of Stellenbosch
Country South Africa 
Sector Academic/University 
PI Contribution We have managed to convenience the senior management in Durham and partner universities to sign a collaboration agreement.
Collaborator Contribution This agreement facilitates the future collaboration between partner universities and Durham University. Partners universities have waived bench fees for visiting academic from Durham. They facilitate the managements of the training events delivered by researchers from Durham.
Impact This agreement facilitates the exchange of researchers and academic staff in Science faculties in the partners' universities. The bench fees were waived for visiting academics.
Start Year 2016
 
Description Discussion Forum: Thinking about hazards: a cross-disciplinary discussion 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Postgraduate students
Results and Impact A discussion forum on "Thinking about Hazards" held in Durham on 10 March 2016. This forum is organised in liaison with the Durham Universiy Institute of Hazard, Risk and Resilience. PhD students from Durham presented their work on unsaturated soil mechanics. PhD students and researchers in South African partners universities have also participated in the forum via WebEx (video conference system).This forum offered excellent opportunities for knowledge transfer and engagement across the network as they were reflected in the thorough discussion followed the presentations.
Year(s) Of Engagement Activity 2016
URL https://www.dur.ac.uk/ihrr/news/pastevents/?eventno=29369
 
Description Mitigation strategy against sinkhole collapse risks 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact A one-day workshop was held on 8 Dec 2016, attended by academics from the University of Pretoria, engineers and engineering geologists from industry active on development on dolomite land which included representatives from the Cities of Tshwane and Ekurhuleni and the SA National Department of Public works. The workshop comprised a number of technical presentations featuring recent work about development on dolomite land. A number of deficiencies regarding the enforcement of legislation governing the development and abstraction of water from dolomite land were identified. Some of these are associated with poor performance of regulators. It was a decision that the group will draft a letter to the Engineering Council of South Africa to a request to inform the Minister of Public Work of the dangers if the required standards are not enforced.
Year(s) Of Engagement Activity 2016
URL https://www.dur.ac.uk/esrciaa/gcrf/sinkhole/
 
Description Short course on numerical analysis of unsaturated soil 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact A three-day course on GIS and coupled hydro-mechanical methods were delivered by Dr Mohammed Seaid at the University of Pretoria. The course was attended by 26 persons which included graduates students and staff from the University of Pretoria and a number of engineers from industry.
Year(s) Of Engagement Activity 2016
 
Description Workshop on unsaturated soil mechanics research in South Africa 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Postgraduate students
Results and Impact A Videoconference via WebEx where 7 South African researchers presented their work on unsaturated soils to Durham researchers. It was organised on 23 June. The workshop sparks questions on the engineering practice in South Africa
Year(s) Of Engagement Activity 2016