Clay Slides Research Articles

3D large deformation modeling of the 2020 Gjerdrum quick clay landslide

A quick clay slide in Gjerdrum, Norway, occurred at 4 a.m. on 30th December 2020, killing ten people and destroying houses, roads, and other infrastructures. Approximately 1.35 million cubic meters of clay were released, a large volume liquefied, and debris was transported almost two kilometers downstream. An investigation following the slide determined that the slide was initialized in a 30-meter-high slope after 2-to-2,5-meter vertical erosion in a small creek running along the toe of the slope. After the initiation, the slide developed retrogressively in the order of 500 meters backward and sideways over a period of about 2 minutes. A conventional geotechnical slope stability analysis explains the initial slide. However, more advanced numerical tools are needed to simulate the retrogressive mechanism and the debris flow. The aim of the paper is to demonstrate a 3D Material Point Method model to capture some of the mechanisms involved from initiation until the debris comes to rest and how this method can be used to reproduce and study the processes involved in large deformation landslides.

Technical and economic challenges for Arctic Coastal settlements due to melting of ice and permafrost in the Arctic

The safety of Arctic coastal villages/settlements is of concern due to melting of the ice cover and the permafrost in the Arctic. The immediate concerns for Arctic coastal settlements are due to a number of causes. These causes can be listed as follows: increased distances of open seas during the storm season, larger storm surges due to longer distances of open water without ice cover, larger waves due to longer fetch lengths, increased permafrost melting caused by warmer summer seasons, larger erosion of melted shoreline, increased number of storms causing accumulation of storm erosion effects, large flooding events destroying houses and facilities as well as infrastructure and fresh water reservoirs. There will be possible offshore slides due to melting of offshore permafrost with potential for tsunami generation, and riverbanks will erode due to the melting of permafrost. Slides caused by increased wetness (for example quick clay slides) will occur and housing and water reservoirs will be damaged. Furthermore, the winter seasons are shorter where winter roads can be utilized and the seasons for hunting from the ice cover is shorter. There will be economic losses for the villages/settlements due to changing climate and in the case of needed relocation of the villages, the economic costs are huge. The paper discusses the effects of these concerns and will suggest certain mitigating measures, which only to a limited extent can relieve the situation. The ultimate solution will be relocation of the inhabitants and in some cases the settlement may be relocated to safe location further inland.

Statistical Insights Regarding Fully Softened Shear Strength

The fully softened shear strength (FSS) concept is a practical approximation of the mobilized drained shear strength of first-time slides in stiff-fissured clays. There has been a recent increase in interest in measurement and estimation of FSS secant friction angle (FSS-ϕ′sec) to develop correlations for preliminary design and cost approximation. However, such correlations do not help in understanding the cause and effect relationship between soil properties and FSS-ϕ′sec. In this study, a laboratory database containing FSS-ϕ′sec values (output) and soil properties (inputs) of several overconsolidated clays is used to develop a predictive model for FSS-ϕ′sec (output or response). The goal is to detect which inputs from the whole parameter space dominate the response while creating an accurate prediction tool to provide statistical insights regarding the FSS-ϕ′sec. The proposed methodology is used to assess and quantify the relationships among variables, estimate testing device effects on FSS-ϕ′sec, and analyze the danger of extrapolation due to model constraints. The applicability of the predicted FSS-ϕ′sec is also evaluated and compared. Recommendations regarding the studied prediction tools for slope stability design in stiff-fissured clays are provided.

Integrated scanning for quick clay with AEM and ground-based investigations

Near shore, high latitude lowlands throughout Canada, Norway, Sweden, Finland and Russia are prone to a particular geohazard – quick clay. The key geotechnical properties of quick clay, also called Leda clay in Canada, are a very small remoulded shear strength (< 0.5 kPa in Norway after NGF, 2011; and <0.4 kPa in Sweden after Rankka et al., 2004) and consequent high sensitivity (= undisturbed/remoulded shear strength). These properties stem from the fact that this formerly marine clay has been leached by ground water owing to postglacial uplift, losing salt ions that stabilized the flocculated clay structure. When quick clay fails, it liquefies and leads to retrogressive landslides that have caused massive damage and claimed lives both in North America and Europe. Quick clay can be found in sedimentary areas close to the coast and below the marine limit, areas that are attractive for human settlements. Two of Norway’s four most populated urban areas (Oslo and Trondheim) are located in quick clay areas. Detailed study and mapping of areas prone to quick clay slides relies on geomorphology, quaternary geology and point information from geotechnical boreholes and laboratory tests. This is a labour intensive and long lasting process that, in Norway, has been going on since the 1980s and only the most vulnerable parts of the country are mapped so far. The detailed hazard mapping continues, at a pace of a hand full of municipalities a year (Figure 1).

Creep response in shear of clayey geo-materials under saturated and unsaturated conditions

Translational slides in clays are often characterized by long-lasting intermittent movements associated with the fluctuations of pore-water pressure. Physically-based models designed to support hazard analysis of landslide movements and early warning systems require the integration of time-dependent (viscous) constitutive models for the shear displacements because landslide movements are typically controlled by the viscous behaviour of the clay geo-material. This paper presents an investigation of the viscous response of a clay geo-material under saturated and unsaturated conditions. Creep and relaxation tests have been first carried out on saturated clay samples by means of direct shear box. To gain a conceptual understanding of the viscous response of the clay in shear, mechanical analogues were considered based on combinations of springs and dashpots. Preliminary tests on unsaturated samples were finally carried out to gain a first insight into the viscous response of the clay under unsaturated conditions.

Integrated database for rapid mass movements in Norway

Abstract. Rapid gravitational slope mass movements include all kinds of short term relocation of geological material, snow or ice. Traditionally, information about such events is collected separately in different databases covering selected geographical regions and types of movement. In Norway the terrain is susceptible to all types of rapid gravitational slope mass movements ranging from single rocks hitting roads and houses to large snow avalanches and rock slides where entire mountainsides collapse into fjords creating flood waves and endangering large areas. In addition, quick clay slides occur in desalinated marine sediments in South Eastern and Mid Norway. For the authorities and inhabitants of endangered areas, the type of threat is of minor importance and mitigation measures have to consider several types of rapid mass movements simultaneously. An integrated national database for all types of rapid mass movements built around individual events has been established. Only three data entries are mandatory: time, location and type of movement. The remaining optional parameters enable recording of detailed information about the terrain, materials involved and damages caused. Pictures, movies and other documentation can be uploaded into the database. A web-based graphical user interface has been developed allowing new events to be entered, as well as editing and querying for all events. An integration of the database into a GIS system is currently under development. Datasets from various national sources like the road authorities and the Geological Survey of Norway were imported into the database. Today, the database contains 33 000 rapid mass movement events from the last five hundred years covering the entire country. A first analysis of the data shows that the most frequent type of recorded rapid mass movement is rock slides and snow avalanches followed by debris slides in third place. Most events are recorded in the steep fjord terrain of the Norwegian west coast, but major events are recorded all over the country. Snow avalanches account for most fatalities, while large rock slides causing flood waves and huge quick clay slides are the most damaging individual events in terms of damage to infrastructure and property and for causing multiple fatalities. The quality of the data is strongly influenced by the personal engagement of local observers and varying observation routines. This database is a unique source for statistical analysis including, risk analysis and the relation between rapid mass movements and climate. The database of rapid mass movement events will also facilitate validation of national hazard and risk maps.

Development of the submarine channel in front of the Nidelva River, Trondheimsfjorden, Norway

The Nidelva submarine channel is a 4 km long and up to 100 m deep erosional feature seaward of a former outlet of the river Nidelva, in Trondheimsfjorden, Norway. Mechanisms of channel evolution and sedimentary processes associated to its development are revealed by analyzing the sea bed morphology and the stratigraphy of the fjord sediments, based on high resolution seismic data, swath bathymetry imaging and gravity cores. Seismic data suggest that the submarine channel is eroded into Late Pleistocene clays filling a bedrock depression. A thick Holocene deltaic succession overlay the glacio-marine clays. Seismic facies suggest that turbidity currents likely initiated downcutting of the channel in the Early-Holocene. These flows were guided by sea bed morphology and bedrock exposures, favouring confluence and acceleration. The area was subjected to glacio–isostatic rebound and rapid fall of relative sea-level in the Holocene. This resulted in a fast delta progradation likely with an enhanced activity of delta derived sediment gravity flows promoting incision. In Mid- to Late-Holocene, such flows, including hyperpycnal flows, were responsible for deep incision of the channel. Laminated clay-rich beds are interpreted as deposited by the overspill of turbiditic flows along the channel and likely originate from large terrestrial quick clay slides. In the last 2000 years, erosive flows initiated by mass wasting along the coast controlled the evolution of the channel after the mouth of the Nidelva River moved to a more easterly position in the embayment. Present slope failure along the channel flanks seems to be controlled by the distribution of the laminated clay-rich layers in the stratigraphy.

Mapping of quick clay formations using geotechnical and geophysical methods

Quick clay has been involved in most serious, large clay slides in Sweden, Norway, and Canada. This paper describes geotechnical and geophysical methods that can be used to locate and map the extent of quick clay formations. Surface resistivity measurements and four different sounding methods have been tested. The results have been compared with sensitivities determined using fall-cone tests. The investigation shows that there is a correlation between sensitivity and electrical resistivity, which can be used to discriminate between marine clays that have been leached sufficiently to possibly form quick clay and those for which the salt content remains sufficiently high to prevent this. Although the most reliable evaluation of the variation in sensitivity was obtained by the CPT with additional measurement of total penetration force, this investigation suggests that any sounding method that uses a constant rate of advance into the ground and in which the penetration force applied on the top of the rods is measured may be used for quick clay mapping.

Distribution of clay minerals in the process streams produced by the extraction of bitumen from Athabasca oil sands

AbstractThis study investigates the affinity of clay minerals in oil sands for the water‐continuous tailings and hydrocarbon‐continuous froth streams produced from the extraction of bitumen from oil sands. Clay minerals in oil sands processing impact bitumen flotation in separation vessels, emulsion formation during froth treatment, and fine tailings behaviour.X‐ray diffraction of oriented clay slides and random powder samples were used to quantify the clay minerals in the oil sands ore and process streams. Particle size distribution and clay activity balances were also conducted around the extraction process.The degree of partitioning during the conditioning and flotation stages in a batch extractor was determined by the surface properties of the clay minerals present. The water‐continuous tailings stream was further separated into fine and coarse tailings fractions through sedimentation. The bulk of the clay minerals reported to the fine tailings stream. Illite and mixed layered illite‐smectite partitioned less to the hydrocarbon‐continuous froth than kaolinite. Also, the illite‐smectite in the froth stream appeared to be different from the illite‐smectite in the water continuous streams.

Large, prehistoric clay slides revealed in road excavations in Buvika, mid-Norway

Several excavated sections along new roads in Buvika, mid-Norway, display records of large, prehistoric clay slides. Slightly undulating but otherwise intact laminated clay, with minor amounts of unsorted or sorted coarser-grained debris, appears in the sections. Folding, shearing and internal slide surfaces have also been recorded, and the deposits are interpreted as slide debris. Slide-scar morphologies are diffuse or absent for most of these deposits, and the inferred slide mechanism is translation and rotation of blocks on a thin layer of remoulded quick clay. One section cuts through a slide block inside a classic, morphologically well-defined quick-clay slide scar. Varying results from 14C-datings of organic material in the deposits give only maximum ages of the slide events. The style of sliding reflected in several sections differs from slide events in the area known from historical records. These younger slide events seem to be characterised by collapse and remoulding of thicker quick-clay layers. The present study of slide deposits gives information on processes and deformation history of the slides. It is suggested that the gradual formation of quick clay has an important impact on long-term landscape degradation and on the character of the present day landscape. There may be far more signs of slide activity in Norwegian valleys than solely indicated by slide scars and also in the relatively high-lying parts of the valley fill, such as interfluve areas.

Facies characteristics, morphology and depositional models of clay-slide deposits in terraced fjord valleys, Norway

Many bedrock-confined fjord valleys along the Norwegian coast contain thick accumulations of fine-grained sediments that were deposited during and after the last deglaciation. The deposits gradually emerged above sea level due to glacioisostatic uplift, and fjord marine sedimentation was gradually followed by shallow marine and fluvial processes. During emergence terraces and river-cut slopes were formed in the valleys. Subsequent leaching of salt ions from the pore water in the marine deposits by groundwater has led to the development of quick clay. The deposits are subject to river erosion and destructive landslides involving quick clay. Most slides are of prehistoric age. Others are known from modern observations as well as from historic records. Landforms such as distinct slide scars or the hummocky terrain of slide deposits may be strongly modified by secondary processes. In addition, deposits from the most liquid part of quick clay slides may have planar surfaces. Clay-slide deposits on a fluvial or deltaic terrace, therefore, are not always easily recognized from morphology, and only exposures may reveal their internal structures and allow them to be distinguished from overbank flood sediments. Detailed sedimentological work shows that slide deposits in such setting consist of distinct facies containing reworked marine sediments. We propose three facies successions of clay-slide deposits that form a continuum. The dominant components of these succession types are: slightly deformed blocks of laminated clay and silt (A), highly deformed clay and silt with gravel clasts (B) and massive to stratified clay and silt with scattered clasts (C). We suggest that in many cases a basal muddy diamicton is a characteristic, and possibly diagnostic feature. Processes and depositional models are interpreted from the different succession types. The results may be relevant for identifying clay-slide deposits elsewhere and may be useful during general mapping of fjord marine deposits and characterization of slide-prone areas as well as during identification of prehistoric slides.

Clay slides in the Målselv valley, northern Norway: Characteristics, occurrence, and triggering mechanisms

The distribution of a large number of clay slides in the Målselv valley, northern Norway, is analysed and put into context with the stratigraphic organization of the valley-fill sediments. About 32% of the landslides larger than 10 4 m 3 occur close to the valley margins, where mud is either exposed or at shallow depth. About 57% of the landslides occur mid-valley, where relatively thin (< 15 m) coarse-grained deltaic sediments overlay fine-grained marine and glaciomarine sediments, and about 11% of the landslides occur in front of ice-contact deposits. The slide-prone areas are all characterized by the occurrence of heterogeneous sediments (interbedded clay, silt and sand), in addition to the presence of steep slopes eroded by rivers. The heterogeneous nature of the sediments probably enhanced groundwater drainage and leaching of salts from the clay, increasing sensitivity. Thus, the distribution and organization of the valley-fill sediments and groundwater drainage probably controlled the position of the slide scars and sliding planes. Since deglaciation of the valley (11,500 BP–present), isostatic rebound has enhanced fluvial incision and the creation of steep slopes due to a fall in relative sea level of up to 80 m. Arcuate-shaped, ‘bottleneck’ landslide scars ranging from c. 10 4 to 10 7 m 3 in size is the dominant morphological signature of the slides, typical for quick clay slides or earth flows involving fluid mud. Their most common triggering mechanism is probably erosion at the toe slopes by the river Målselv or its tributaries. River erosion close to the valley margin, where glaciomarine and marine sediments are present, seems to give the most severe slides. The overall valley-fill organization controls the distribution of clay slides, which may apply to other fjord valleys having similar sediment distribution.

Quick clay—A case study of chemical perspective in Southwest Sweden

Quick clay, a soil that changes from normal firm ground to a liquid mass when it is disturbed, has been involved in most of the large and serious clay slides in Sweden, Norway and Canada. The location, time of occurrence and size of quick clay slides are difficult to predict and large slides may cause great devastation. Some geochemical studies of Swedish quick clay were done in the 1960s and early 1970s, but no systematic studies of the interrelationships of pore water chemistry, mineralogy, geotechnical properties and other parameters on quick clays in Sweden have been published. Such studies are of national and general interest because of the many combinations of rock flour source areas and sedimentation conditions that occurred across central Sweden and into the Baltic Sea area during deglaciation. In this study, geotechnical properties related to the in situ chemistry at one quick clay site were extensively studied, and spot sampling was conducted at two other locations in Southwest Sweden. In this area the clay minerals mainly are non-expanding phyllosilicate minerals (illite) and primary minerals (quartz, feldspar), which is consistent with previous studies of quick clay mineralogy. Extensive leaching has occurred at all three locations. At the extensively studied site, Surte, the lowest salinity was found at the greatest depth, inferring that the leaching by fresh water was accomplished by water movement upward and laterally through the sediment from the underlying bedrock. This is consistent with the local setting where bedrock hills rise sharply to over 100 m above the marine sediment surface. An artesian pressure would also be anticipated at this location. There is a correlation (negative) between sensitivity and salinity but there is an indication that the maximum salinity or electrical conductivity consistent with the quick clay behaviour is higher than reported elsewhere. However, for high sensitivities the salinity is about the same as reported elsewhere. In the deepest part of the borehole, there is a higher content of Fe and Al in the pore water, indicating reduced state. Further work is needed to confirm the difference in salinity and to investigate the possible interplay of salinity and potential dispersing agents such as the role of anoxic conditions, in this region. Further work is especially needed in the locations where the sediment accumulation occurred under lower salinity conditions. At all three locations, high remoulded shear strength and low sensitivity have been seen near the surface together with a decrease in pore water cation concentrations.

Regional distribution of environmental hazards in Norway

The registrations of out-payment due to hazards in Norway by the Norwegian National Fund for Natural Disaster Assistance (the NDAF-Statens Naturskadefond 1962-1994) and the Norwegian Natural Perils Pool (the NPP-Norsk Naturskadepool 1980-1994) are the basis for the regionalization of hazards in Norway. Four different regions at the county level are identified: 1. More og Romsdal, Sør-Trondelag, Nord-Trøndelag and Nordland, with most damage and highest disbursement; 2. Rogaland, Hordaland, Sogn og Fjordane, Troms and Finnmark; 3. Østfold, Oslo & Akershus, Hedmark, Oppland, Buskerud and Telemark; and 4. Vestfold, Aust-Agder and Vest-Agder, with the lowest disbursement. Storms are the most important hazard, followed by floods. In Østfold and Sør-Trondelag clay slides rank second, as do snow avalanches in More og Romsdal. Rock falls are of surprisingly low importance.

Viscous analysis of submarine flows : Edgers, L; Kalsrud, K Norw Geotech Inst PublN166, Dec 1986, 9P

Submarine slope instability and subsequent soil flows may have disastrous consequences for offshore structures and pipe lines. A theoretical viscous flow model has been applied to analyse some submarine slides and subaerial quick clay slides for which flow velocity observations are available. The submarine slides range in size from a small coastal slide which ran out about 1 km to the enormous Grand Banks slide which ran out more than 700 km at apparent speeds greater than 25 m/s. The viscous soil flow analysis modelled the runout of these slides very well, indicating that soil flow may be an important factor in the runout of sometimes very large and rapidly moving submarine slides. The analyses of field data provide some guidance on the appropriate soil input viscosities. There are still many questions regarding the development of flow geometry and these may be answered by means of detailed field studies of existing submarine slide deposits.

Landslides and surficial deposits in urban areas of British Columbia: A review

Landslides in surficial deposits occur commonly in the urban environment of British Columbia. Three groups of surficial materials are especially prone to slope failure. These are glaciomarine sediments, glaciolacustrine deposits, and glacial till that mantles steep mountain slopes. The geological and geotechnical characteristics of these three materials are examined and discussed.The sensitivity, metastable fabric, and geological heterogeneity of glaciomarine sediments control their landslide behaviour. A regional variation in glaciolacustrine deposits is suggested. The Southern Interior and Columbia deposits are dominated by silt varves and those of the Northern Interior by clay varves. The silts are sensitive and collapsible under certain moisture and loading conditions. The effect of urbanisation on these silts in the semiarid Southern Interior is considerable. The retrogressive behaviour of slides in silts and clays in urban areas is also examined.Open-slope and channelled debris flows in till mantles are discussed. They occur mainly on steep slopes in the Coast Ranges as a response to heavy, relief-induced rainfall. The effect of urbanization on slope stability is also discussed.

Mather and landslides: 1838

In the first report of the Geological Survey of the state of Ohio there is an account of erosion along the shore of Lake Erie in the vicinity of Cleveland. This is illustrated by a plate which includes a good section of a landslip on retrogressive circular failure planes. Since the report was published in 1838, this observation of the curved failure surfaces in clay slides antedates those of Logan (1842) and Collin (1846). The use of groynes for shore protection is suggested and the phenomenon of piping appears to be suggested.

Grain size, mineralogy and chemistry of a quick-clay sample from the Ullensaker slide, Norway

A detailed laboratory study was made of a quick-clay from a recent quick clay slide at Ullensaker in Romerike, approximately 40 km northeast of Oslo, Norway. The material is a Quaternary glacial clay, deposited in a marine basin. It was lifted isostatically above sea level during Late Pleistocene time. The clay was fractionated according to grain size and appropriate size fractions were subjected to mineralogical and chemical analyses. Relationships between mineralogy, chemistry and particle size were sought.

First-Time Slides in Over-Consolidated Clays

(a) After a slide has taken place the strength on the slip surface is equal to the residual value. The residual strength is associated with strong reorientation of the clay particles and is represented by an angle of shearing resistance $= which in most clays is considerably smaller than the value of 4’ at peak strength (Fig. 1). (b) First-time slides in slopes in non-fissured clays correspond to strengths only slightly less than the peak. (c) First-time slides in fissured clays correspond to strengths well below the peak. (d) Some form of progressive failure must be operative to take the clay past the peak. This could be simply the result of a non-uniform ratio of stress to strength along the potential slip surface; but probably the fissures play an important role as stress concentrators and in leading to softening of the clay mass. (e) Granted a progressive failure mechanism the limiting strength would be residual, and it is therefore reasonable to express the actual strength at the time of failure as a function of the upper (peak) and lower (residual) limits, i.e. by the residual factor. (f) In natural slopes of London CIay the strength has fallen approximateIy to the residual value. (g) The residual strength obtains on pre-existing shear surfaces, whether these are the result of tectonic shearing or old landslides.

Sphagnum portoricense and Discelium nudum in New York

On March 5, 1961, Dr. A. LeRoy Andrews wrote me, You will be pleased to learn that you collected Sphagnum portoricense on Long Island. This is new to New York State and, in fact, carries it a step farther north, the farthest heretofore having been the pine barrens of New Jersey, where I, among others, have collected it. This discovery, mentioned in passing in Andrews' article on S. pylaesii (Bryol. 64: 213. 1961), was made on September 5, 1959, about two miles north of Manorville on the northwest side of Sandy Pond. Growing with it or nearby were S. cuspidatum var. torreyi and S. compactum. About one-quarter of a mile south S. flavicomans was found in a swale, and a little east of Sandy Pond S. fimbriatum and much S. cuspidatum var. torreyi were found growing in the open at the boggy margin of a pool. On a second visit (August 15, 1961), it was determined that S. portoricense is the most abundant species of Sphagnum along the northwest shore of Sandy Pond, where it forms a belt about 10-20 ft. wide and 100-200 yds. long. (I am grateful to Irwin Brodo for his aid in finding the place where this interesting species grew.) Discelium nudum has been found in Schoharie County, New York, at Boucks Falls, north of the village at Gilboa, and at the south end of the hamlet of North Blenheim. The large and conspicuous clay slopes at Gilboa do not show any sign of it, and so far the clay slides in southern Tompkins and northern Tioga have been barren; to quote Dr. Andrews, That is fussy.