Displacement-pile behaviour in a soft marine clay

1994 ◽  
Vol 31 (2) ◽  
pp. 181-191 ◽  
Author(s):  
B.M. Lehane ◽  
R.J. Jardine
Keyword(s):  
Key Words ◽  
Effective Stress ◽  
Field Experiments ◽  
Imperial College ◽  
Marine Clay ◽  
Sensitive Clay ◽  
Sensitive Marine Clay ◽  
Major Factors

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.

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
Keyword(s):  
Key Words ◽  
Surface Load ◽  
Marine Clay ◽  
Case Record ◽  
Final Value ◽  
Effective Stresses ◽  
Sensitive Clay ◽  
Sensitive Marine Clay

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.

An earthflow in sensitive Champlain Sea sediments at Lemieux, Ontario, June 20, 1993, and its impact on the South Nation River

1994 ◽  
Vol 31 (3) ◽  
pp. 384-394 ◽  
Author(s):  
S.G. Evans ◽  
G.R. Brooks
Keyword(s):  
Water Quality ◽  
Stability Number ◽  
The South ◽  
Marine Clay ◽  
Landslide Mass ◽  
Sensitive Clay ◽  
Leda Clay ◽  
Sensitive Marine Clay ◽  
The Stability ◽  
Landslide Debris

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.

Stabilisation de la berge rive nord de l'aménagement hydroélectrique La Grande 1

2000 ◽  
Vol 37 (1) ◽  
pp. 40-55
Author(s):  
Michel Massiéra ◽  
Jean-Pierre Tournier
Keyword(s):  
Special Design ◽  
Marine Clay ◽  
River Sand ◽  
River Bank ◽  
The North ◽  
North Bank ◽  
Sand Deposit ◽  
Sensitive Clay ◽  
Sensitive Marine Clay ◽  
Bank Stabilization

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.

Decompensation placental dysfunction: diagnostics and delivery tactics

2017 ◽  
pp. 66-68
Author(s):  
V.I. Boyko ◽  
◽  
S.A. Tkachenko ◽  
Keyword(s):  
Pregnant Women ◽  
Key Words ◽  
Retrospective Analysis ◽  
Control Group ◽  
Present Stage ◽  
Placental Dysfunction ◽  
Perinatal Pathology ◽  
Delivery Times ◽  
Case Rate ◽  
Major Factors

The objective: depression of frequency of perinatal pathology at women with decompensation form of placental dysfunction by improvement of the main diagnostic and treatment-and-prophylactic actions. Patients and methods. 154 pregnant women in gestation term from 22 to 40 weeks were surveyed. Depending on features of course of pregnancy and families of all surveyed it was divided into 4 groups. The group of the retrospective analysis was made by 45 pregnant women with decompensation placental dysfuction, the group of prospective research included 109 pregnant women of whom the main group was made by 38 women with decompensation form of placental dysfunction, the group of comparison included 47 pregnant women with the compensated form of placental dysfunction. The control group was made by 24 pregnant women with the uncomplicated course of pregnancy and labors. The complex of the conducted researches included clinical, ehografical, dopplerometrical, laboratory, morphological and statistical methods. Results. Use of advanced algorithm of diagnostic and treatment-and-prophylactic actions allows to increase efficiency of diagnostics of decompensation form of placental dysfunction for 33.3%, and rational tactics of a delivery leads to depression of perinatal pathology for 22.7%. Conclusion. Decompensation placental dysfuction is one of the main reasons for perinatal mortality and a case rate at the present stage. Use of the algorithm of diagnostic and treatment-and-prophylactic actions improved by us allows major factors of risk of this complication and the indication for change of tactics and delivery times. Key words: decompensation placental dysfunction, diagnostics, delivery tactics.

A field study of competition and interaction between Lemna minor and Lemna trisulca

1989 ◽  
Vol 67 (10) ◽  
pp. 2904-2911 ◽  
Author(s):  
Alexander L. McIlraith ◽  
Gordon G. C. Robinson ◽  
Jennifer M. Shay
Keyword(s):  
Life History ◽  
Field Study ◽  
Key Words ◽  
Field Experiments ◽  
Lemna Minor ◽  
Survey Methods ◽  
The Other ◽  
Transplant Experiment ◽  
Replacement Series ◽  
Vegetative Biomass

Field experiments and survey methods were used to assess competition and interaction between Lemna minor L. and Lemna trisulca L. at Delta Marsh, Manitoba. Sites were dominated by one or the other species or codominated by both. Replacement series experiments predicted codominance of L. minor and L. trisulca in an unshaded eutrophic site but predicted L. minor dominance when run for a longer time. Similar experiments conducted in a shaded eutrophic site predicted L. minor dominance. Addition series experiments showed that intraspecific and interspecific competition occurred in the unshaded site. In a eutrophic unshaded ditch, high densities of L. minor suppressed L. trisulca. In a eutrophic shaded site, high densities of L. minor and green algae inhibited L. trisulca, and in a sunny, less eutrophic site high density of each species inhibited the other. In a transplant experiment, L. minor biomass in shaded enclosures approached that found naturally in two shaded sites. Lemna trisulca persisted when shaded. Vegetative biomass trends in an unshaded eutrophic marsh ditch indicated spring and fall L. trisulca dominance and summer L. minor dominance. Shaded eutrophic sites were dominated by L. minor, whereas a less eutrophic site was dominated by L. trisulca. A model is developed to explain dominance patterns, and seasonal life-history responses are considered. Key words: Lemna, duckweed, competition, interaction, resources, light, nutrients.

scholarly journals A Formação de Dolinas em Áreas Urbanas: o Caso do Bairro de Cruz das Armas em João Pessoa-PB (The Formation of Dolines in Urban Areas: The Case of Cruz das Armas in João Pessoa-PB)

2011 ◽  
Vol 4 (1) ◽  
pp. 161
Author(s):  
Max Furrier ◽  
Saulo Roberto de Oliveira Vital
Keyword(s):  
Key Words ◽  
Urban Areas ◽  
Shuttle Radar Topography Mission ◽  
Dynamic Interaction ◽  
The State ◽  
Digital Terrain ◽  
Terrain Models ◽  
Geological Map ◽  
Major Factors ◽  
The City

Evidências de dolinas são bastante comuns na cidade de João Pessoa-PB, mas ainda pouco estudadas. As dolinas são consideradas depressões fechadas, circulares, associadas a rebaixamento topográfico coadjuvado por fenômenos cársticos de sub-superfície, caracterizando um carste inumado. Assim como as encostas e os vales entalhados, as dolinas também são alvo da intensa ocupação nas cidades por parte da camada social menos favorecida, tendo em vista, serem áreas bastante deprimidas e susceptíveis a enchentes. A partir de então, esta pesquisa tem como objetivo, identificar os principais fatores de predisposição do terreno para criação de relevo do tipo carste, exclusivamente as dolinas e os riscos associados. Para isso, foram levantados dados sobre o embasamento geológico a partir do mapa geológico do Estado da Paraíba, e informações sobre a morfologia do terreno, coletadas a partir do radar SRTM (Shuttle Radar Topography Mission), além das observações de campo. Como produto, obteve-se os Modelos Digitais do Terreno, por meio dos quais se tornou possível realçar as evidências de subsidência do relevo local, corroborado pelas informações sobre a geologia local, marcada por uma intensa interação dinâmica entre as Formações Barreiras e Gramame (Sub-bacia Sedimentar Alhandra). Concluiu-se que os planos de falha existentes nos calcários da Formação Gramame contribuem de forma conspícua para percolação da água nessa formação perfazendo uma reação química capaz de dissolver o calcário, rebaixando a Formação Barreiras que se encontra sobreposta, dando origem a depressões circulares.Palavras-Chave: Dolinas, Formação Gramame, Formação Barreiras, João Pessoa. The Formation of Dolines in Urban Areas: The Case of Cruz das Armas in João Pessoa-PB ABSTRACTEvidence of dolines are much common in João Pessoa, the capital of the state of Paraíba, but they are still poorly studied. The dolines are considered to be closed and circled depressions, associated to a topographic smoothing assisted by subsurface karstic phenomenons, characterizing an inhumed karst. As well as the slopes and the carved valleys, the dolines are also intensively occupied in the city by people who are less favoured, what represents a serious problem considering that these are depressed areas and susceptible to flooding. The research aims to verify the major factors of the terrain susceptibility to the karst features formation, exclusively the dolines, and the associated risks. In view of this objective, the geological basement data were gathered from the geological map of the State of Paraíba and the terrain morphological information were collected from the SRTM radar (Shuttle Radar Topography Mission), besides the observations of the fieldwork developed. As result, the Digital Terrain Models were achieved enabling to present the evidences of the local subsidence features, corroborated by the information about the local geography marked by a intense dynamic interaction between Barreiras and Gramame Formation (Alhandra Sedimentary Sub-Basin). The analysis showed that the failed plans presented in the limestones of the Gramame Formation contribute evidently to the percolation of water on this formation totalizing a chemical reaction able to dissolve the limestone, lowering the superposed Barreiras Formation, what give rise to circular depressions.   Key-Words: Dolines, Gramame Formation, Barreiras Formation, João Pessoa.

Thirty years of secondary consolidation in sensitive marine clay: Reply

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