scholarly journals Thirty years of secondary consolidation in sensitive marine clay

1990 ◽  
Vol 27 (3) ◽  
pp. 315-319 ◽  
Author(s):  
C. B. Crawford ◽  
M. Bozozuk

This case record shows that when a surface load is applied to a sensitive, normally consolidated clay, the effective stresses increase rapidly to the measured preconsolidated stresses, and remain at that level while consolidation continues for several decades. Only after more than 30 years was there an indication that the in situ effective stresses were beginning to increase to their final value. These observations have important implications with respect to the design of foundations in such areas. Key words: consolidation, foundations, secondary consolidation, sensitive clay settlements, marine clay.

1994 ◽  
Vol 31 (2) ◽  
pp. 181-191 ◽  
Author(s):  
B.M. Lehane ◽  
R.J. Jardine

The paper presents the results of field experiments performed using the Imperial College instrumented displacement pile in a soft, sensitive marine clay at Bothkennar, Scotland. These results are compared with data from similar programmes of experiments performed in other clay types with this pile so that some of the major factors controlling displacement-pile performance may be identified. Key words : displacement pile, instrumentation, sensitive clay, effective stress design.


1973 ◽  
Vol 10 (2) ◽  
pp. 246-260 ◽  
Author(s):  
L. S. Brzezinski ◽  
L. Shector ◽  
H. L. Macphie ◽  
H. J. Vander Noot

On a project just west of the City of Montreal pile heave was experienced during the installation of groups of cast in situ cased expanded base concrete piles, driven through about 30 ft (9 m) of sensitive marine clay to end bearing in a glacial till formation. The paper describes the observed heave occurrence and discusses factors affecting pile and soil heave. Of special interest is the behavior of the piles during retapping since a number had final refusal elevations which were both high and low with respect to initially installed elevations. Possible explanations for this behavior and considerations pertinent to installation procedure, site inspection, load testing, and specifications for this type of pile are discussed within the paper.


1994 ◽  
Vol 31 (3) ◽  
pp. 384-394 ◽  
Author(s):  
S.G. Evans ◽  
G.R. Brooks

A large (est. volume 2.8 × 106 m3) landslide occurred in sensitive Leda clay on the east bank of the South Nation River at Lemieux, Ontario (45.4°N, 75.06°W), on June 20, 1993. The earthflow involved an area of about 17 ha and retrogressed a total of 680 m, 555 m into the flat plain above the river. No lives were lost but a motorist was injured when he drove into the landslide crater. The 1993 landslide occurred 4.5 km downstream of the well-known 1971 South Nation River landslide along a stretch of river that had experienced other historical landslides in 1895 and 1910. A band of earlier, undated, retrogressive sliding, between 100–130 m in width, was present at the base of the slope that failed in 1993, and the earthflow was probably triggered by a reactivation of these failures. Borehole information obtained in 1986 and 1987 in the vicinity of the landslide indicates that a zone of soft, sensitive marine clay existed beneath the flat farmland, which was overlain by a stiffer cap consisting of laminated marine-estuarine sands and deltaic silts and sands. The morphology of the debris suggests a mechanism that involves the fluidization of much of the landslide mass and subsidence, translation, and rotation of cap blocks. The stability number for the site was approximately 9.6, suggesting that the flow could have occurred as a result of extrusion of the soft sensitive clay layer due to undrained cap loading. Landslide debris temporarily blocked the South Nation River, causing flooding upstream and adversely affecting water quality downstream. Key words : landslide, earthflow, sensitive clay, debris hazards, water quality.


2000 ◽  
Vol 37 (1) ◽  
pp. 40-55
Author(s):  
Michel Massiéra ◽  
Jean-Pierre Tournier

The La Grande 1 (LG-1) hydroelectrical project, part of the La Grande Complex in Northern Quebec, required the construction of a 2444 m long dyke on the north bank of the river. The presence of sensitive marine clay, covered with deltaic sand and silt deposit, and river sand deposit, called for special design features such as downstream bank and upstream bank stabilization berms to avoid the occurrence of potentially disastrous retrogressive slides. This paper describes the geotechnical and hydrogeological conditions of the northern terrace and presents the different construction phases of the riverbank stabilization, with emphasis on the control of groundwater pressures in the lower aquifer by the use of relief wells.Key words: sensitive clay, river bank, dyke, rockfill, relief well, slope stability.


2020 ◽  
pp. 71-74
Author(s):  
M.M. Melnyk ◽  
◽  
S.V. Nespradko ◽  
I.V. Goncharuk ◽  
M.V. Marchenko ◽  
...  

The objective: analyse the effectiveness of diagnosis and treatment for early cervical cancer. Materials and methods. Analysed 107 cases of women’s disease on CIN ІІІ, cancer in situ, they were on treatment in National cancer institute and Kyiv dictrict cancer dispensary from 2010 till 2015 years. Results. Diagnosed percent relapse CIN ІІІ, cancer in situ contain 4.57% uninvasive and invasive form – 0.94%. Conclusion. According diagnostic CIN ІІ and CIN ІІІ is recommended to do treatment conization and dynamic dispensary observation. Are making complex program of infection HPV16, 18. In appering of margins resection some elements of tumor after wider conization by forms of cancer in situ. Many of expansive burns in cervical glands, in making of reproductive function, going disease (nodel leiomyoma of corpus uteri etc). In perspective is accept the notion of looking after and screening research of considering infection HPV16, 18 on CIN І, CIN ІІ. Key words: cervical cancer, сancer in situ, CIN І–ІІІ, diagnostic, treatment, conization.


1972 ◽  
Vol 9 (2) ◽  
pp. 127-136 ◽  
Author(s):  
M. Bozozuk

Large negative skin friction loads were observed on a 160 ft (49 m) steel pipe test pile floating in marine clay. The test pile was driven, open-ended, on the centerline of a 30 ft (9 m) high granular approach fill on the Quebec Autoroute near Berthierville. Since the installation was made in 1966 the fill has settled 21 in. (53 cm), dragging the pile down with it. Negative skin friction acting along the upper surface of the pile was resisted by positive skin friction acting along the lower end as it penetrated the underlying clay. Under these conditions the pile compressed about [Formula: see text] (2 cm). Analysis of the axial strains indicated that a peak compressive load of 140 t developed at the inflection point between negative and positive skin friction 73 ft (22 m) below the top of the pile. Negative and positive skin friction acting on the upper surface of the pile exceeded the in situ shear strength and approached the drained strength of the soil where excess pore water pressures had dissipated. At the lower end where the positive excess pore pressures were high and relative movement between the pile and the soil was large, the positive skin friction approached the remoulded strength as measured with the field vane. Skin friction was increasing, however, as positive escess pore pressures dissipated.This paper shows that skin friction loads are related to the combination of (a) in situ horizontal effective stresses, (b) horizontal stresses due to embankment loads, and (c) horizontal stresses due to differential settlement of the fill.


1990 ◽  
Vol 27 (1) ◽  
pp. 58-67 ◽  
Author(s):  
Mohammed G. Kabir ◽  
Alan J. Lutenegger

An investigation was conducted to demonstrate the applicability of cylindrical piezocone and flat piezoblade tests for providing reliable estimates of the coefficient of consolidation in clays. Coefficients of consolidation were calculated from piezocone dissipation tests for different degrees of consolidation using theoretical time factors to provide a comparison with laboratory oedometer tests. Three techniques were developed to calculate the coefficient of consolidation from piezoblade dissipation tests. Results from in situ pore pressure dissipation tests were compared with laboratory oedometer tests performed on undisturbed samples oriented in both the vertical and horizontal directions, to provide reference values of cv and ch. The results of investigations conducted at several clay sites are presented. Key words: in situ tests, piezocone, piezoblade, coefficient of consolidation, oedometer test, clays.


1991 ◽  
Vol 28 (3) ◽  
pp. 468-469
Author(s):  
C. B. Crawford ◽  
M. Bozozuk

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