Quick Clay Research Articles

The Twentieth Terzaghi Lecture

In spite of our present very advanced analytical capabilities, our present ability to predict actual field behavior is, in many cases, woefully inadequate. Four cases are described to illustrate one of the reasons why actual and predicted performances are sometimes so widely divergent—namely, failure to understand how a soil might respond over time to changed conditions. The four cases are: (1) The aging of quick clay after sampling, in which the remolded strength increases in samples maintained at constant water content; (2) time effects in freshly densified or deposited sand, in which natural sand deposits can lose strength if disturbed but regain strength over time periods of weeks to months; (3) apparently sound lime‐stabilized soil that swells and disintegrates starting a few years after construction; and (4) the failure of excess pore pressures to dissipate as predicted during the consolidation of soft clays. Study of each of these problems has led to an understanding of the responsible phenomena an...

The causes and effects of aging in quick clays

The physicochemical properties of a clay from La Baie, Quebec were found to be typical of Champlain quick clays: very low plasticity, liquidity index greater than 3, sensitivity greater than 500, and pH of about 9.5. The mineralogy is characterized by the abundance of primary or "rock flour" minerals such as feldspar, quartz, amphibole, and calcite, with illite as the principal clay mineral. The pore water chemistry consists predominantly of sodium bicarbonate. Low concentrations of sulfate, calcium, and magnesium and high alkalinity and pH are attributed, in part, to anaerobic sulfate-reduction processes taking place in situ.Quick clay samples stored in the laboratory showed signs of aging regardless of the storage procedure. The remoulded strength and the liquid limit increased with time, whereas the sensitivity, the liquidity index, and the pH decreased. The water content, plastic limit, and undisturbed strength remained practically unchanged. The pore water concentrations of calcium, magnesium, and sulfate increased by severalfold.The aging phenomenon is attributed, for the most part, to the oxidation of iron sulfide, which results in the formation of iron hydroxide and sulfuric acid. The production of acid causes the dissolution of calcium carbonate, which increases the concentration of divalent cation in the clay, thereby reducing interparticle repulsion and increasing the remoulded strength. The oxidation of organic matter, resulting in the formation of carbonic acid, also contributes to the aging by its effect on the solubility of calcium carbonate. Key words: aging, chemical reactions, physicochemical phenomena, sensitivity, time effects.

Block sampling for quick clays (In Norwegian) : Lacasse, S; Berre, T Norw Geotech Inst PublN150, 1984, P4

Block sampling for quick clays (In Norwegian) : Lacasse, S; Berre, T Norw Geotech Inst PublN150, 1984, P4

Properties of a low-swelling smectitic marine clay of interest in soil engineering

Smectite is generally a high-swelling clay. However, the smectite found in marine quick clays in the Ariake Bay area of Japan is a low-swelling clay like illite and kaolinite. The low swelling properties of an Ariake marine clay are investigated here in terms of consolidation, swelling, and shrinkage characteristics. The void ratios in compression curves of soils containing sodium are lower at 0.01 N than at 1.0 N NaCl concentration, and the slopes of swelling curves are independent of salt concentration in the pore water and cation valency. These tendencies are contrary to those observed for montmorillonite and a paddy soil containing high-swelling smectite. Measurements of swelling pressure suggest that the smectite in the Ariake marine clay exhibits little intracrystalline swelling even after saturation with Na. The volume shrinkage of the Ariake marine clay by air-drying is smaller than that of the paddy soil. Key words: compressibility, marine clays, smectite, swelling.

A centrifugal model study of slope instability in Ottawa area Champlain Sea clay

Problems of serious slope instability in quick Champlain Sea clay, also known as Leda clay, found in eastern Canada, have been the subject of debate regarding mechanisms of failure and relevant strength characteristics. Eight intact samples of Ottawa area Champlain Sea clay were retrieved, formed into 19 different slope configurations, and tested as reduced-scale models on the Cambridge University 4.25 m diameter 150 g geotechnical centrifuge. Of these, 14 showed some manner of slope instability, ranging from deep intact slope movement, to slope degradation, to flowsliding. Speculation is made on the importance of time-dependent horizontal stress release, on the possibility that prototype failure is not circular and rotational, and that uplift may affect subsequent retrogressions in prototypical landslides but not initial failure. Inconsistencies in the behaviours of models were attributed in part to certain possible limitations on reduced-scale modelling; these included the effects of the unscaled network of fissures and the loss of strength as a function of displacement rather than of strain. Key words: centrifuge, clays, failures, simulation models, slope stability.

Effect of pH on the Rheology of Marine Clay from the Site of the South Nation River, Canada, Landslide of 1971

AbstractThe pH of Na-saturated, carbonate-containing and carbonate-free Leda clay, at salinities of 2 and 10 g/liter, was decreased from pH 8 to 4 by the addition of HCl. The Bingham yield stress, as determined with a coaxial viscometer, increased in all materials as the pH decreased. Above about pH 7 the 2-g/liter materials had a lower yield stress at any water content than the 10-g/liter materials, whereas, below about pH 6.8 the yield stress of the carbonate-containing soil at a salinity of 10 g/liter was lower. For the carbonate-free material, the change occurred at about pH 6.2. The influence of salinity on the remolded shear strength of these materials was pH-dependent. A yield stress increase with decreasing pH was likely due to a change in ion saturation. The carbonate-free material exhibited a maximum yield stress at about pH 5.5–6.2, depending on salinity. The isoelectric points for oxides and clay mineral edges most probably account for the existence of the maximum.

Towards a general model of quick clay development

Torrance (1983) has recently reviewed factors producing high sensitivity in clayey sediments and proposed a general model for quick clay development. He suggested that the mineralogical requirement for quick clay behaviour to develop is that low activity minerals must predominate in the sediment. This is also the essential mineralogical requirement of the inactive‐particle, short‐range‐bond hypothesis of high sensitivity (Smalley, 1971, 1972a, 1976; Cabrera & Smalley 1973; Smalley, Ross & Whitton, 1980). The predominance of low activity minerals causes most of the interparticle bonds to be of the short‐range variety which allow/promote the‘quick’ behaviour—the transition from solid to liquid. In Canadian or Scandinavian quick clays the short‐range bond requirement is largely met by the abundance of finegrained primary mineral particles. The very sensitive clays involved in the Tauranga landslide in New Zealand (Smalley et al., 1980) owed their sensitivities to their content of inactive spheroidal halloysite particles. By many definitions the Tauranga material is a quick clay and its existence provides us with another window through which to view the quick clay problem. Torrance observed that for a quick clay to develop the sediment must have an open structure with a high void ratio. In a classic Canadian quick clay this structure is obtained by the slow sedimentation of fine particles in the salty Champlain Sea; in the Tauranga soil an open structure is obtained by air‐fall sedimentation of the initial volcanic particles.

An application of Soderblom's rapidity test to Canadian soils

The parameter ‘rapidity’ has been proposed by Soderblom to give an additional useful property measurement for sensitive soils. The suggested Soderblom rapidity test has been applied to various Leda clay samples. The results indicate that the test is unsuitable in its present form due to the strong inter-particle cementation of the Canadian quick-clays.

The importance of pore water chemistry on mechanical and engineering properties of clay soils

The classical Coulomb-Terzaghi shear strength equation, (cr— tan depends not only upon mechanical and mineralogical factors, but to a high degree upon the total chemistry of the system. Changes in chemistry owing to natural and anthropogenic factors may change the strength properties of a given clay soil at a given water content. The classical example of slow acting chemical changes is the development of quick clay properties. Modern infiltration of different electrolytes and detergents from leaking sewer systems may change shear strength and compressibility of the ground. These processes are different in clays of expanding and nonexpanding minerals. The importance of the different cation species seems to depend upon valency and polarizability. Influence of anions is more complicated and depends upon interaction with edge charges and the crystalline properties of the clay minerals.

A Comparison of Marine Clays from Ariake Bay, Japan and the South Nation River Landslide Site, Canada

The smectite-dominated Ariake Bay marine clay, the sensitivity of which can increase upon leaching to yield quick clay, is found to conform to the general model for quick clay development that has been proposed on the basis of the properties and behaviour of the Canadian and Scandinavian quick clays. While the Ariake Bay soil is more plastic than the Leda clay from the South Nation site, its plasticity and its yield stress at constant water content, as determined using a coaxial viscometer, decrease with salinity in the same manner. The removal of citrate-dithionite soluble materials decreases the yield stress in both soils although the Ariake Bay soil, from which more is removed, is more dramatically affected. Dispersants decrease the yield stress of both soils. Why, in contrast to most smectites, the smectites in the Ariake Bay marine clay are of low activity and have their activity decrease upon leaching, thereby allowing the development of quick clay behaviour, remains uncertain but it may be related to dominance by high-iron smectites.

Stability of natural slopes in quick clays : Aas, G Proc 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm, 15–19 June 1981V3, P333–338. Publ Rotterdam: A. A. Balkema, 1981

Stability of natural slopes in quick clays : Aas, G Proc 10th International Conference on Soil Mechanics and Foundation Engineering, Stockholm, 15–19 June 1981V3, P333–338. Publ Rotterdam: A. A. Balkema, 1981

Towards a general model of quick clay development

ABSTRACT Within the clear definition of a quick clay as being a soil which has a sensitivity greater than 30 and a remoulded strength less than 0.5 kPa, a general model for quick clay development is presented, based on the influences of various material properties and natural processes on the sensitivity and remoulded strength. The influences are separated according to depositional requirements and post‐depositional factors and according to whether the influence is to increase the undisturbed strength or to decrease the remoulded strength. Depositional factors are the requirements for a flocculated structure and the dominance of low activity minerals. Post‐depositional factors are cementation and slow load increase, which increase the undisturbed strength, and little consolidation, leaching and dispersants, which decrease the remoulded strength. The application of the model to marine, brackish water and freshwater sediments is discussed.

1982 Student Professional Paper: Undergraduate Division: Slab Slides of the Alaska Earthquake of 1964

The Good Friday earthquake of 1964 brought unexpected destruction to the city of Anchorage, Alaska. In the Anchorage area, the quake registered 8.5 on the Richter scale. Though the seismic vibrations were ruinous, the major cause of damage to the city was slab slides. These slides were related to the quick clay properties of Bootlegger Cove Clay which underlies most of Anchorage. Prolonged seismic activity triggered huge masses of earth, initially bounded on one side by a bluff, to move laterally upon a horizontal and planar shear surface within the clay. The lateral displacement of many slides was extensive, and one major slide transported earth more than half a mile. Grabens formed as a result of faulting and collapsing of the sediments within the slab slide. Although the Bootlegger Cove Clay bed is shallow, its presence greatly augmented the destructiveness of the earthquake.

Marine Quick Clays from Ariake Bay Area, Japan

It has been indicated that the sensitivity of the marine sediment in Ariake Bay area varies between 8 and 50, and rarely is 100. Recently, however, extra quick clays with sensitivity greater than 50 and sometimes near 1000 were found in this area. In order to find the cause of the formation of extra quick clays, the sediment samples of slightly- very quick and extra quick clay obtained from two sites in Ariake Bay area were analyzed with respect to their mineralogical, chemical, and geotechnical properties. There was no appreciable difference in clay mineralogy between the sediment samples from two sites, and they contained smectite as the main mineral. The principal difference between the sediment samples of slightly-very quick and extra quick clay was in the salt concentration in the pore water, which was in the range of 1. 02 ~ 10. 4 g/l and 0. 05 ~ 1. 08 g/l, respectively. The experiments of salt addition to extra quick clays and salt leaching from medium quick clays demonstrated that extra quick clays could be developed by leaching out of the salt in the pore water. The fact that extra quick clays can be developed in the sediment in Ariake Bay area, in spite of the presence of smectite as the main mineral, was interpreted by considering smectite in the clays to be of low-swelling type.

Organic matter and the geotechnical properties of submarine sediments

Continental slope deposits off Peru and Oregon where coastal upwelling is a pronounced oceanographic process possess significant concentrations of organic carbon. Geotechnical properties are altered to varying degrees by the organic matter. Organic matter absorbs water and causes clay-size particles to aggregate forming an open fabric. This causes unusually high water contents and plasticity and exceptionally low wet bulk densities. Some of these deposits show notable increases in shear strength, sensitivity and degree of apparent overconsolidation. Owing to the unique geotechnical properties, sediment stability characteristics are considered to be poor in situations of excess pore pressures. Failure appears to take the form of a fluidized flow somewhat similar to the quick clays of Scandinavia.

Significance of amorphous material relative to sensitivity in some Champlain clays: Discussion

In considering the significance of amorphous materials to the sensitivity of Canadian clays the authors have made an informative contribution to the sensitive-clay literature. The authors have established a comprehensive framework for analysis that other researchers would do well to follow in subsequent studies. In the writer's opinion these analyses should be considered in the light of all research into amorphous materials and a brief review of Norwegian work would be appropriate. The Norwegians led sensitive-clay research into the 1960's and some aspects of this work, augmented by work recently performed by the writer, are relevant to the paper under discussion. The presence of amorphous compounds in sensitive clays has been recognized by several Norwegian workers (Moum 1967; Bjerrum et al. 1969; Lerken 1970). The amorphous matter appears to be insoluble-iron and aluminium compounds, which are liberated from mineral phases by in situ weathering. Other soluble cations, notably K+, Ca2+, and Mg2+ also are liberated by mineral disintegration; these do not form amorphous precipitates but they can have an important electrochemical influence on the clay. It is evident from laboratory observations that mineral disintegration becomes active when the leaching process introduces fresh waters, which result in a change of pH and oxidation capacity (Bjerrum 1967; Moum 1967). The interaction of these released cations with the clay system has been summarized by Lerken (1970); the cations may be leached out with the remaining salts in the pore water, enter adsorbed positions by displacing more weakly adsorbed cations, or precipitate as insoluble amorphous compounds. From work concerning chemical additions to quick clays Lerken (1970) concluded that there is a fundamental differ-

Repeated compressive loading of leda clay : Raymond, G P; Gaskin, P N; Addo-Abedi, F Y Can Geotech J, V16, N1, Feb 1979, P1–10

Repeated compressive loading of leda clay : Raymond, G P; Gaskin, P N; Addo-Abedi, F Y Can Geotech J, V16, N1, Feb 1979, P1–10

Comparison of undrained shear strength results obtained by different test methods in soft clays

The Cambridge self-boring pressuremeter and the Norwegian Geotechnical Institute field vane apparatus have been used at three sites of different subsoils. Two of the sites, South Gloucester and National Research Council of Canada grounds, are located in Leda clay in the Ottawa area. The third site features a highly plastic lacustrine clay in northwestern Quebec. At this site tests were conducted beside and under a fill that had undergone 1 m of surface settlement. At all three sites, the pressuremeter yields higher strengths than the field vane apparatus.Conventional and special laboratory tests were conducted on large diameter tube or block samples from South Gloucester. It is found that the conventional triaxial compressive strength is intermediate between the pressuremeter and field vane strengths. In accounting for the strength discrepancy, factors such as anisotropy, stress path, and disturbance have been studied in the light of the results of the special tests.

Sensitive soils and quick clays. Special issue : Smalley, I.J. (editor) Engng Geol, V14, N2–3, Aug 1979, 137P

Sensitive soils and quick clays. Special issue : Smalley, I.J. (editor) Engng Geol, V14, N2–3, Aug 1979, 137P

Quick clays and other slide-forming clays : Kerr, P F Engng Geol, V24, N2–3, Aug 1979, P173–181

Quick clays and other slide-forming clays : Kerr, P F Engng Geol, V24, N2–3, Aug 1979, P173–181