Quick Clay Research Articles

Estimation of Undrained Shear Strength of Soil from CPTu Data

The estimation of undrained shear strength ( ) from Cone Penetration Test with pore pressure measurement (CPTu) for two sites was investigated in this research. The CPTu cone parameters: net cone resistance ( ), excess pore pressure ( ) and effective cone resistance ( ) were used to estimate the for the two sites and the values obtained were compared with the undrained shear strength in triaxial compression ( calculated from Anisotropically Consolidated Undrained Compression (CAUC) triaxial test results. For the clayey silt site, the undrained shear strength from the CAUC tests are higher compared to the values obtained from the CPTu, and the highest correlation was obtained from the effective cone resistance parameter . For the quick clay test site, the value and were relatively the same and showed stronger correlation as compared to the clayey silt site. The measured from the cone parameter had the highest correlation. It was concluded that and yields good correlation with the CAUC results for the clayey silt and quick clay test sites respectively as compared to the other con parameters.

Landslide and ravine distributions related to ground conditions in elevated marine deposit in Mid-Norway

The Trondheim and Gauldal areas in Mid-Norway are characterized by thick marine deposits from the ice age and deglaciation period. The following glacio-isostatic rebound has led to river incisions in the valleys and extensive landsliding and ravine erosion. This study is based on data from an upgraded Quaternary geological map of this region for the areas below the highest sea level after the last ice age, with a focus on landslide scars and ravines. The study has a multidisciplinary approach, which is important in order to get a good regional geological understanding of the ground conditions and the landscape development. This means that geological, geomorphological, geotechnical, geophysical and hydrogeological data are used. The study area is divided into six parts, based on natural topographical divisions and the distribution of landslide scars and ravines. Factors influencing the development of sensitive clay and the triggering of landslides are described for each area; these include sediment distribution, thicknesses and stratigraphy, bedrock topography, the degree of leaching of clay, groundwater conditions, the number, size and shape of landslides, and the distribution of rivers, streams and ravines. The study shows that the size, behaviour and erosional potential of the main river or stream influence the landscape development to a high degree. The erosional basis, stratigraphy and presence of bedrock are essential for leaching and the development of quick clay.

The Strength Behaviour of Cement-Treated Clay at Different Moisture Content and Curing Time

This study involves the study on the properties of clay samples from Pagoh at natural state and stabilized state with Portland cement. The main objective of the study is to identify the unconfined compression strength of original and stabilized clay at different moisture content and curing time. The tests carried out include proctor test, moisture content and unconfined compression test (UCT). Therefore, clay was mixed with Portland cement at a concentration of 10 % by weight of dry soil for the proctor test. The original and stabilized samples were tested in an UCT at different curing period of 14 and 28 days. At the end, the actual result shows that the unconfined compressive strength of the stabilized clay is higher than the original. It is believed that the value of strength is highly affected by the different moisture content and curing time. Therefore, the control of water content and treatment time is essential to produce a strong and safe foundation for any construction purpose. As a result, new stabilization methods to prevent landslides in natural and developed quick clay slopes will be developed. In conclusion, cement stabilization improves the workability of clay.

QuickAware: a virtual reality tool for quick clay landslide hazard awareness

Disaster emergency management is crucial for safeguarding lives and the environment in the face of natural and human-caused calamities, such as quick clay landslides. Disaster emergency management encompasses hazard identification, prevention, response, and recovery, most of which require knowledge and information acquired through training initiatives. Quick clay landslides pose a substantial hazard in regions like Scandinavia, Canada, Alaska, and Russia. With numerous historical incidents, knowledge-based awareness of quick clay landslide hazards is of paramount importance. In recent years, the area of application of virtual reality (VR) has grown tremendously from the entertainment industry to the military, to mental health, to hazard identification training and our daily lives. VR has been widely employed in hazard identification and prevention, safety training, evacuation, search and rescue, and damage identification of hazards. This study outlines the design, development, and implementation of QuickAware, a VR tool designed to create awareness of quick clay hazards. The development process of the tool started with a co-design approach where stakeholder experts were brought to collaborate in setting up VR scenarios and defining the VR environment contents. The contents were then conceptualized and translated into a VR experience. The novelty of the tool is that it immerses users in a realistic experience, allowing them to engage directly with the causes and consequences of quick clay landslide disasters which would be dangerous in real-life. The usability of the VR tool was examined by surveying 16 participants. The preliminary results of the survey indicated that the tool has a promising value in improving awareness creation for quick clay landslide hazards.

Using various geotechnical techniques for challenging conditions at the West Link project

AbstractThe city of Gothenburg in western Sweden is currently experiencing the construction of one of the biggest infrastructure projects in the country – The West Link (Västlänken). The West Link is an 8 km double‐track railway project, of which 6 km will be through underground tunnels with two new stations, Haga and Korsvägen, and construction of a bigger Central station. The construction of the project began in May 2018 and the finalization is expected in 2026. The project is split into five different sections which were awarded and are being executed individually. The widely varied geological profile of the area consisting of weak‐to‐very weak clay and silty‐sandy‐gravelly moraine along with challenging local conditions like existing waterways, traffic routes, and buildings requires a range of soil improvements and shoring system solutions suiting the local conditions. Some techniques executed by Keller include dry deep soil mixing (DDSM) to stabilize the quick clay to facilitate excavation, jet grouting for water sealing, excavation support in addition to soil improvement purposes, uplift piles over a flowing river, drilled steel piles at the bottom of excavation pit as foundation support, drilled steel pile wall, and sheet piling. Apart from technical challenges, the West Link has strong focus on adopting sustainable solutions like methods to reduce disposal of wet masses from jet grouting. A team of experts of design and execution from different parts of the world is working together to make it a success story.

EXECUTION OF VARIOUS GEOTECHNICAL WORKS FOR CHALLENGING PROJECTS IN SWEDEN AND SLOVENIA

The city of Gothenburg in western Sweden is currently experiencing the construction of one of the biggest infrastructure projects in the country - The West Link (Västlänken). The West Link is an eight km double track railway project, of which six km will run through underground tunnels. The project is split into five different sections, which were awarded and being executed individually. The widely varied geological profile of the area consisting of weak to very weak clay (often referred as ‘quick clay’) and silty, sandy and gravelly moraine along with challenging local conditions like existing waterways, traffic routes and buildings require a range of soil improvements and shoring system solutions suiting the local conditions. Keller has been executing Dry deep soil mixing (DDSM) to stabilize the quick clay to facilitate excavation and jet grouting for water sealing and excavation support in addition to soil improvement purposes. Execution of uplift piles over a flowing river, drilled steel piles at the bottom of excavation pit as foundation support, drilled steel pile wall and sheet piling for excavation support are other examples of geotechnical solutions executed as customized to site requirements. The knowledge gained from challenging international projects is further applied to key local projects, such as those in Slovenia, where the advantages of developed geotechnical technologies and procedures are leveraged in the most effective ways. Two significant projects have recently been executed using this approach. Firstly, ground improvement works were undertaken for the new Central Correctional Facilities Project in Ljubljana, involving the use of premixed vibro concrete columns (PVCC). This project was carried out on an abandoned quarry that had been filled with construction waste over the past few decades. The second project involves landslide prevention measures, specifically the reconstruction of an existing anchored wall on a highway near Maribor. To address this, longer and higher capacity geotechnical anchors were installed at heights of up to 8 meters.

High‐resolution P‐ and S‐wavefield seismic investigations of a quick‐clay site in southwest of Sweden

AbstractSeismic investigations were performed at a site in the southwest of Sweden where major quick‐clay landslides have occurred in the past. Given the potential high risk of the area and the presence of medium infrastructures, the site posed a need for detailed investigations in a wide depth range and in high resolution. A high‐fold seismic survey was designed and conducted along two profiles using a 1–2 m receiver and shot spacing in order to retrieve both P‐ and S‐wavefield seismic images from vertical component data. The data were analysed by combining first‐break traveltime tomography and surface‐wave analysis as well as P‐ and S‐wavefield reflection seismic imaging. Using the first breaks, P‐wave velocity (VP) models were estimated, indicating the bedrock topography along the profiles and the sediment characteristics. The S‐wave velocity (Vs) models were estimated from the surface waves and indicated areas of low shear strength. Combined with VP and Vs models, this permits the estimation of VP/VS, a parameter that can indicate areas with high water content, significant for the detection of quick clays and possible liquefaction issues. The results are integrated with the P‐ and S‐wave reflection seismic images and compared with other geophysical investigations, such as magnetic and gravity data that were collected along the profiles.

Quick clay monitoring using distributed acoustic sensing: A case study from Rissa, Norway

Quick clay avalanche is one of the most devastating landslide types worldwide. Hence, an early warning system is in demand to mitigate the fatal consequences caused by such events. To address this, distributed acoustic sensing data are collected in an area containing quick clay deposits between July 2021 and February 2022 in Rissa, Norway, while a new road is constructed on the quick clay. Road construction can induce unwanted changes to the mass balance in the clay, and previous landslides have been triggered by such changes. For this purpose, passive and active data are collected to test and compare various analysis methods. Using extracted Rayleigh wave dispersion from active sledgehammer shots, shear-wave velocity depth profiles covering the first 15 m could be estimated and compared using a linearized and a nonlinear surface wave inversion method. Furthermore, ambient noise crosscorrelation is used to obtain the dispersion from the ambient noise and associated shear-wave velocity profiles, providing two possible data collection methods for the early warning system. The obtained dispersion curves and the estimated shear-wave velocity profiles show small time-lapse variation during the acquisition period (up to approximately 23 m/s), where the variation is within one standard deviation. Such a small variation suggests that the construction work and the extra load added to the quick clay do not alter the quick clay’s properties. Nevertheless, the obtained results capture the nonrepeatability effects within the acquisition period and provide reference curves for the study area at undisturbed conditions and valuable information for future comparisons to refer to potential failure scenarios. This is the first step in exploring an early warning system for quick clay landslides using fiber-optic cables. Further work will investigate the possibility of automatizing the system and improving the accuracy of the sensing system.

Stabilisation of Soft Clay, Quick Clay and Peat by Industrial By-Products and Biochars

The stabilisation of soft soils using the traditional binders cement and quicklime are known to emit large amounts of carbon dioxide. To reduce this carbon footprint, substitutes such as industrial by-products have been thoroughly tested as viable alternatives for soil stabilisation. However, recent research has also shown that biochar from biomass pyrolysis can in some instances have a positive stabilisation effect and even result in a carbon-negative footprint. This paper presents a laboratory study to investigate the stabilisation effect of five industrial by-products and four types of biochar on three natural Norwegian soils: two clays with low and high water contents and one peat with a very high water content. The soils and binders were characterised by their mineralogical and chemical compositions. The biochars had varying stabilisation effects on the clays when combined with cement, with some negative stabilisation effects, whilst the effect was very beneficial in the peat, with a strength increase of up to 80%. The industrial by-products showed opposite results, with beneficial effects in the clays and a strength increase of up to 150%, but negative stabilisation effects in the peat. Correlating the mineralogical and chemical compositions to stabilisation effects was found to be challenging.

Advances in Seismic Imaging of Quick Clays in Sweden

Advances in Seismic Imaging of Quick Clays in Sweden

Adsorption, Hysteresis, and Trapping of Heavy Metals with Environmental Relevance onto Different Quick Clays and Montmorillonite

Adsorption, Hysteresis, and Trapping of Heavy Metals with Environmental Relevance onto Different Quick Clays and Montmorillonite

Ultrahigh-resolution shear-wave reflection imaging of vertical-component data in a quick-clay prone to landslide area in southwest Sweden

We have investigated the potential of ultrahigh-resolution seismic reflection imaging of vertical-component data to identify hazardous conditions in a quick-clay landslide area in southwest Sweden. A high-fold survey with a fine shot and receiver spacing has been acquired using a 5 kg sledgehammer, vertical hit, with the objective of producing a high-quality unaliased shear-wave reflection section retrieved from vertical-component data. On the receiver side, 1C wireless recorders are deployed in a fixed geometry juxtaposed to a landstreamer of 3C-microelectro mechanical system (MEMS)-based units, which recorded in a roll strategy to cover most of the profile length. Particle motion analysis of main reflections has been conducted on the 3C MEMS sensors, given their side-by-side location with the wireless recorders, to inspect the wave polarization. Distinct shear-wave reflections in an extremely slow shear velocity medium (70–100 m/s) imply a vertical super resolution of 1–2 m down to a bedrock level of 40 m deep. Interestingly and as shown in earlier studies, quick clays appear to overlie the coarse-grained horizons justifying why their high-resolution imaging can be significant for quick-clay landslide studies and a better understanding of potential risks. Two shallow reflections are delineated through a combination of first-break traveltime tomography for P and S waves and reflection seismic processing for P- and S-reflections of the vertical-component data. After seismic imaging and borehole data correlation, the shallowest reflection is interpreted to be from coarse-grained materials interbedded within normally consolidated clays and the deepest one from an undulating bedrock. Interpretations of the S-S processing outcomes indicate that the coarse-grained layers are not homogeneous because of the generation of strong shear-wave diffractions, suggesting the presence of either large boulders or patchy sandy-silty conditions.

Ageing/thixotropy effects on strength and compressibility in Leda clay and polymer-amended clayey tailings

Evidence of ageing has been reported in natural deposits of sedimentary clays, dredged sediments, and in clay-rich oil sands tailings, and such time-dependent behaviour has been observed to influence their long-term settlement and strength development characteristics. The ageing phenomenon can, therefore, have important implications for the reclamation of such deposits. This research investigated ageing in polymer-amended tailings and Leda clay monitoring relatively small (10 cm high) laboratory samples for over 100 days. Both tailings and natural clay were found to develop increased strength, sensitivity, and higher pre-consolidation pressure and reduced compressibility. The correlation between fall cone shear strengths and pre-consolidation pressures was strong for both the natural clay and the clayey tailings, though this ratio was different in the tailings and the clay. The Leda clay appeared to reabsorb some of its bleed water, which was found to be due to the transition of some free water to absorbed water after 80 days. Using a concept developed from ageing experiments in artificial clays, it was found that shear strengths measured after an “early equilibrium state” correlated strongly with shear strengths measured near the end of ageing. This is promising for quantifying the potential for ageing on compressibility without having to resort to year-long experiments.

Interplay Between Friction and Cohesion: A Spectrum of Retrogressive Slope Failure

AbstractRetrogressive failures occur in slopes consisting of sensitive materials such as snow or quick clay. They can be triggered by a small disturbance at the slope toe, but can cause propagated failure spreading miles away. Understanding the physical mechanism and predicting the retrogressive failure process are particularly important. Previous studies have discussed the failure criteria, the soil properties or the method of numerical modeling of retrogressive slope failure. However, little attention has been paid to the microscopic failure mechanism, especially relating to various possible failure patterns. In this study, multiscale modeling is incorporated to study the physical mechanism of different retrogressive failure patterns, including earth flow, flowslide and spread failure, within a unified framework. Utilizing multiscale analysis, we found that earth flow failure is related to the shear failure of granular materials. In contrast, the development of macroscopic shear bands is accompanied by tensile failure. As shear and tension failures are typical failure mechanisms of frictional and cohesive materials, it is deduced that friction and cohesion effects play key roles in different retrogressive failure patterns. Therefore, the distributions of attractive and repulsive contact forces are explored and a novel parameter η is proposed to quantify the interplay between friction and cohesion. Further analysis proves that η can capture the effect of friction and cohesion and distinguish different retrogressive failure patterns. Finally, a spectrum of retrogressive failures for a granular slope is established, in which the failure mechanism is explained by the changeable dominant effect, that is, frictional or cohesive in soil.

Salt leaching by freshwater and its impact on seafloor stability: An experimental investigation

Offshore freshened groundwater (OFG) has been documented in many continental margins worldwide. OFG systems are dynamic, expanding and contracting with falling and rise sea-levels. OFG has long been thought to be an important geomorphic agent in continental margins, either via active discharge at the seafloor, which can erode depressions, or the generation of excess pore pressure, which can deform sediments and cause slope failure. It has also been proposed that OFG flow can drive the loss of sediment shear strength via salt leaching, when seawater in pores is replaced by freshwater. Here, we measure changes in the geotechnical properties of seafloor clayey silt due to salt leaching using flushing experiments, and assess the implications of these changes on the stability of siliciclastic continental margins with 2D limit equilibrium modelling. We document a ∼ 50% decrease in undrained cohesive strength of seafloor sediment after flushing, as well as a decrease in its shear strength, bulk density, and moisture content, which is similar to that reported for subaerial quick clays undergoing salt leaching. When applied to a theoretical submarine domain 300 m wide by 100 m high, we estimate that salt leaching can trigger slope failure when the thickness of the flushed layer is >3.5 m or when the slope gradient is >3°. Such conditions are primarily satisfied on the continental slope or the shallow seafloor close to the shoreline. Salt leaching by OFG flow merits consideration as a potential mechanism destablising submarine sedimentary slopes.

Positive Correlation between DYFI Intensity Data and Microzonation Site Classes for Ottawa, Quebec City, and the Metropolitan Area of Montreal

Abstract At the local scale, seismic risk is often poorly estimated when considering equal hazard values across any given community. Indeed, past damaging earthquakes have shown that site conditions, which may amplify or deamplify ground shaking, have an influence on the spatial distribution of damage in urban areas. In eastern Canada, Leda clay deposits from the old Champlain Sea are of particular concern for strong site effects in many parts of Quebec and Ontario. To capture the variability in seismic site response, microzonation maps characterizing average shear wave velocity for the upper 30 m of soil, and predominant resonance frequency have been developed for Montreal, Ottawa, and Quebec City. The maps derived from seismic and borehole measurements have been used to develop shake map scenarios but have not been validated, because there have not been any significantly large, close earthquakes in recent years, and because the seismograph network coverage is not adequate to provide a detailed picture of variations in shaking across a city. Nevertheless, all the three cities are in or near active seismic zones, and felt reports, although less accurate than instrumental data, are numerous and provide a dense dataset showing relative shaking levels across a region. Using intensity data for several moderate earthquakes collected largely via the Canadian internet “Did You Feel It?” page, we systematically compare reported shaking levels to soil conditions indicated by the microzonation maps. This study shows a clear correlation between high-reported intensities and soft soils for Montreal where the number of observations is the largest. The results suggest that intensity data collected via the internet and social media could provide a viable method for validating microzonation maps and shaking scenarios.

Estimating the volume of the 1978 Rissa quick clay landslide in Central Norway using historical aerial imagery

Abstract Quick clay is found across Scandinavia and is especially prominent in south-eastern and central Norway. Quick clay is prone to failure and can cause landslides with high velocities and large run-outs. The 1978 Rissa landslide is one of the best-known quick clay landslides to have occurred in the last century, both due to its size and the fact that it was captured on film. In this article, we utilise Structure from Motion Multi-View Stereo (SfM-MVS) photogrammetry to process historical aerial photography from 1964 to 1978 and derive the first geodetic volume of the Rissa landslide. We found that the landslide covered a total onshore area of 0.36 km2 and had a geodetic volume of 2.53 ± 0.52 × 106 m3 with up to 20 m of surface elevation changes. Our estimate differs profusely from previous estimates by 43–56% which can partly be accounted for our analysis not being able to measure the portion of the landslide that occurred underwater, nor account for the material deposited within the landslide area. Given the accuracy and precision of our analyses, we believe that the total volume of the Rissa landslide may have been less than originally reported. The use of modern image processing techniques such as SfM-MVS for processing historical aerial photography is recommended for understanding landscape changes related to landslides, volcanoes, glaciers, or river erosion over large spatial and temporal scales.

A methodology for mapping of quick clay in Sweden

Landslides may cause severe destruction that affects both the individuals and functions vital for society. Minor landslides in an area with quick clay may trigger secondary slides, influencing a much greater area compared to slides in areas with no quick clay. Today’s expanding societies demand new areas for exploitation. To effectively meet this demand, there is an increased need to identify areas where quick clay may occur. Direct or indirect methods for assessing the presence of quick clay have previously been presented as well as a strategy for site investigations in quick clay areas. In this article, a methodology for mapping quick clays for the Swedish conditions with methods commonly available in this area is presented. The methodology presented in the article is structured in steps with different levels of detail and visualized with two conceptual flowcharts. Depending on the stage of planning, different types of surveys are recommended. The methodology has been applied at four sites where integrated interpretation of airborne and ground geophysical measurements as well as geotechnical investigations have been carried out. The results from two of these sites are presented here. The study reveals that all the methods used have their advantages and limitations. However, a combined use of the information provides much more accurate interpretation that can be used for a more cost-effective future planning and decision-making.

Potassium chloride wells used as quick-clay landslide mitigation: installation procedures, cost–benefit analysis, and recommendations for design

Retrogressive development of landslides in highly sensitive clays (quick clays) may extend several hundred metres upslope from an initial landslide, and liquified slide-debris may impact buildings or infrastructure in the run-out zone. By installing wells filled with potassium chloride (KCl) in quick clays, the salt migrates into the surrounding clay and increases its remolded shear strength, reducing its sensitivity. The salt-stabilized, nonquick clay volume may act as a barrier preventing backward retrogression, thereby contributing to reducing both the area susceptible for being involved in a quick-clay landslide, and the area of the run-out zone. Installation procedures and design guidelines for salt stabilization are examined herein. Installation procedures generating temporary, very small excess pore-water pressures were tested at National Geo-Test Site Tiller–Flotten. Although the benefit-to-cost ratios related to these procedures are small compared to conventional landslide mitigation measures, reducing the installation costs to less than 30 USD per m well and increasing the center distance between the wells may justify salt-stabilization as a landslide mitigation measure. This paper describes experience from testing safe installation procedures, evaluations of cost–benefit and environmental impact, and proposed design guidelines, introducing KCl as an alternative to conventional landslide mitigation-measures in slopes with highly sensitive quick-clay deposits.

AEM in Norway: A Review of the Coverage, Applications and the State of Technology

From the first use of airborne electromagnetic (AEM) systems for remote sensing in the 1950s, AEM data acquisition, processing and inversion technology have rapidly developed. Once used extensively for mineral exploration in its early days, the technology is increasingly being applied in other industries alongside ground-based investigation techniques. This paper reviews the application of onshore AEM in Norway over the past decades. Norway’s rugged terrain and complex post-glacial sedimentary geology have contributed to the later adoption of AEM for widespread mapping compared to neighbouring Nordic countries. We illustrate AEM’s utility by using two detailed case studies, including time-domain and frequency domain AEM. In both cases, we combine AEM with other geophysical, geological and geotechnical drillings to enhance interpretation, including machine learning methods. The end results included bedrock surfaces predicted with an accuracy of 25% of depth, identification of hazardous quick clay deposits, and sedimentary basin mapping. These case studies illustrate that although today’s AEM systems do not have the resolution required for late-phase, detailed engineering design, AEM is a valuable tool for early-phase site investigations. Intrusive, ground-based methods are slower and more expensive, but when they are used to complement the weaknesses of AEM data, site investigations can become more efficient. With new developments of drone-borne (UAV) systems and increasing investment in AEM surveys, we see the potential for continued global adoption of this technology.