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dc.contributor.advisorNordal, Steinar
dc.contributor.advisorAagaard, Per
dc.contributor.authorHelle, Tonje Eide
dc.date.accessioned2017-09-12T12:32:30Z
dc.date.available2017-09-12T12:32:30Z
dc.date.issued2017
dc.identifier.isbn978-82-326-2541-3
dc.identifier.issn1503-8181
dc.identifier.urihttp://hdl.handle.net/11250/2454309
dc.description.abstractHighly sensitive postglacial marine clays, termed quick clays, represent a risk for large retrogressive or progressive landslides such as the well-documented Rissa quick-clay landslide in 1978. Landslide susceptibility presents great challenges for construction work, even in the construction of landslide mitigation measures. Establishing large prevention berms is a commonly used method for increasing slope stability, but can often result in undesirable changes to the terrain. Ground improvement by potassium chloride (KCl) is herein considered as a possible alternative. However, detailed knowledge on geochemistry and its impact on the mechanical behaviour in clays is needed in developing efficient ground-improvement methods based on introducing salt into the clay-water system. In 1972, salt wells filled with potassium chloride (KCl) were installed in a quick-clay deposit at Ulvensplitten, Oslo, Norway with the intention to improve the mechanical properties in the quick clay prior to excavation. Great emphasis was made in documenting the improved geotechnical properties with sampling and vane shear testing in the 2-3 years following the salt-well installations. The ground investigations revealed a significant increase in undrained and remoulded shear strength as well as in the Atterberg limits with increasing concentrations of potassium in the pore water. The collected pore-water chemistry data was, however, scarce and inconclusive with regard to determination of when the clay ceased to be quick; vital for estimating the time required to stabilize the quick-clay volume. The salt-well method is not used as ground improvement today, mainly due to the fact that it is time consuming and the effects are not fully understood or documented with regard to short and long-term effects. In order to establish understanding and documentation, six salt wells filled with KCl were installed in January 2013 in a highly sensitive, low plastic quick-clay deposit at Dragvoll, Trondheim, Norway. The changed pore-water chemistry and improved properties around the wells were investigated by monitoring systems, sampling, laboratory and in-situ tests. The in-situ experiment at Dragvoll provides unique results on improvement of the geotechnical properties isolated to the impact of changed pore-water chemistry. The computer program PHREEQC was used for back calculations of the observed geochemical changes, suggesting that such simulations could be used for estimating the required time to stabilise the quick-clay volume surrounding the wells. Resistivity cone penetrations tests (RCPTU) were conducted in order to evaluate its effectiveness on detecting improved geotechnical properties in-situ. In addition, ground investigations were carried out 40 years after salt-well installations at Ulvensplitten to document the long-term effect of KCl-treated clays. The herein presented correlations between geotechnical properties and pore-water compositions in the salt-treated clay deposit at Dragvoll together with the data from Ulvensplitten, contributes to understand the mechanisms around KCl as ground improvement and its feasibility, as well as determining at which pore-water composition the clays render to be quick. The collected historical and new data validate the KCl-well method as a landslide mitigation method inhibiting retrogressive landslide development, also reducing the risk for progressive Development.nb_NO
dc.language.isoengnb_NO
dc.publisherNTNUnb_NO
dc.relation.ispartofseriesDoctoral theses at NTNU;2017:234
dc.relation.haspartPaper 1: Helle, Tonje Eide; Gjengedal, Ingelin; Emdal, Arnfinn; Aagaard, Per; Høydal, Øyvind Armand. Potassium Chloride as Ground Improvement in Quick Clay Areas – A Preliminary Study. I: Landslides in Sensitive Clays - From Geosciences to Risk Management. Springer 2014, s. 63-74 Is not included due to copyright available at https://doi.org/10.1007/978-94-007-7079-9_6
dc.relation.haspartPaper 2: Helle, Tonje Eide; Bryntesen, Rikke Nornes; Amundsen, Helene A.; Emdal, Arnfinn; Nordal, Steinar; Aagaard, Per. Laboratory setup to evaluate the improvement of geotechnical properties from potassium chloride saturation of a quick clay from Dragvoll, Norway. I: GeoQuebec2015 - Challenges from North to South. : Agora Communication Inc. 2015
dc.relation.haspartPaper 3: Helle, Tonje Eide; Nordal, Steinar; Aagaard, Per; Lied, Ole Kristian. Long-term-effect of potassium chloride treatment on improving the soil behavior of highly sensitive clay – Ulvensplitten, Norway. Canadian geotechnical journal (Print) 2015 ;Volum 53.(3) s. 410-422 http://dx.doi.org/10.1139/cgj-2015-0077
dc.relation.haspartPaper 4: Helle, Tonje Eide; Aagaard, Per; Emdal, Arnfinn; Nordal, Steinar. Monitoring the plume of potassium chloride from wells used as ground improvement in highly sensitive clays. I: In pursuit of best practice - Conference proceedings. Gold Coast, Australia: Australian Geomechnics Society 2016
dc.relation.haspartPaper 5: Helle, Tonje Eide; Aagaard, Per; Nordal, Steinar. In Situ Improvement of Highly Sensitive Clays by Potassium Chloride Migration. Journal of Geotechnical and Geoenvironmental Engineering 2017 ;Volum 143.(10) Is not included due to copyright available at https://doi.org/10.1061/(ASCE)GT.1943-5606.0001774
dc.relation.haspartPaper 6: Helle, Tonje Eide; Aagaard, Per. Predicting Required Time Stabilising Quick Clays by Potassium Chloride. Environmental Geotechnics 2018 https://doi.org/10.1680/jenge.17.00032
dc.relation.haspartPaper 7: Helle, Tonje Eide; Aagaard, Per; Nordal, Steinar. Improving the post-failure properties in quick clays by treatment with potassium chloride. I: Landslides in Sensitive Clays - From Research to Implementation, 2017, s. 45-55, Is not included due to copyright available at https://doi.org/10.1007/978-3-319-56487-6_4
dc.relation.haspartPaper 8: Helle, Tonje Eide; Long, Michael; Nordal, Steinar; Aagaard, Per. Effectiveness of resistivity cone penetration tests in salt-treated highly sensitive clay. Proceedings of the Institution of Civil Engineers - Ground Improvement 2017 ;Volum 170.(3) s. 173-184 https://doi.org/10.1680/jgrim.17.00017
dc.relation.haspartPaper 9: Helle, Tonje Eide; Nordal, Steinar; Aagaard, Per. Improved geotechnical properties in salt-treated highly sensitive landslide-prone clays. Proceedings of the Institution of Civil Engeneers : Geotechnical Engineering 2018 https://doi.org/10.1680/jgeen.17.00071
dc.titleQuick-clay landslide mitigation using potassium chloridenb_NO
dc.typeDoctoral thesisnb_NO
dc.subject.nsiVDP::Technology: 500::Building technology: 530nb_NO


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