Sampling and In-Situ Geotechnical Investigations Offshore

2008 ◽  
pp. 51-51-23 ◽  
Author(s):  
AF Richards ◽  
HM Zuidberg
Keyword(s):  
Geotechnical Investigations

Geotechnical problems related to the building of a tailings dam on sensitive varved clay

1982 ◽  
Vol 19 (4) ◽  
pp. 472-482 ◽  
Author(s):  
N. U. Capozio ◽  
J. M. Ouimet ◽  
M. M. Dupuis
Keyword(s):  
Mine Tailings ◽  
Tailings Dam ◽  
Tailings Pond ◽  
Geotechnical Investigations ◽  
The Stability ◽  
Longitudinal Cracks ◽  
Geotechnical Problems ◽  
Varved Clay ◽  
Thick Deposit

At Noranda Mines in Matagami, Quebec, the construction of a 7-m tailings dam was begun in 1974 by hydraulically depositing mine tailings across a lake. A tailings pond was thus created upstream together with a downstream sedimentation pond regulated by a weir. The presence of longitudinal cracks along the crest of the dam was observed in 1978. This generated some doubts as to the stability of the dam which rests on a 24-m thick deposit of soft sensitive varved clay.Following a first study in 1978, the fissured area was used as a berm for yet another embankment which was built upstream of the unstable zone. In order to reevaluate the stability of the structure and the consequences of an eventual dam rupture, second and third geotechnical investigations were undertaken in 1980 and 1981. This paper presents the main conclusions of these investigations. It also includes the results of borings, in-situ vane tests, and stability analyses that were used to study the problem and made the planning of remedial measures possible.

scholarly journals Stability assessment of submerged lateral and deltaic slopes in Lake Lucerne

2020 ◽  
Author(s):  
Anastasiia Shynkarenko ◽  
Sylvia Stegmann ◽  
Katrina Kremer ◽  
Paolo Bergamo ◽  
Walter Imperatori ◽  
...  
Keyword(s):  
Stability Analysis ◽  
Slope Stability ◽  
Mass Movement ◽  
Slope Stability Analysis ◽  
Tsunami Hazard ◽  
Critical Conditions ◽  
Mass Movements ◽  
Lake Lucerne ◽  
Geotechnical Investigations

<p>Numerous studies indicate that tsunamis do not only occur in oceans but also in lakes. Lake Tsunamis are mainly caused by sublacustrine and subaerial mass movements that can be triggered by seismic or aseismic processes (Schnellmann et al. 2002, Strasser et al. 2007, Kremer at al. 2012, Hilbe and Anselmetti 2015). Such tsunamis can have devastating effects on the surrounding population and infrastructure.</p><p>To assess the tsunami hazard triggered by sublacustrine mass movements, the stability of the lake slopes needs to be examined. As a part of the SNSF funded SINERGIA project “Lake Tsunamis: Causes, Controls and Hazard”, we perform the slope stability analysis based on the comprehensive geotechnical in situ and laboratory dataset for the selected sites of Lake Lucerne, Central Switzerland.</p><p>During 2018-2019 dense geotechnical investigations were carried out along slope-perpendicular profiles at 10 sites where the slopes have failed in the past or are susceptible to failure and included more than 130 in-situ free-fall cone penetration tests with pore pressure measurement (CPTu) and laboratory analysis of 30 short sediment cores. Already existing reflection seismic dataset complements these data and provides the thickness of different sediment layers.</p><p>1D undrained, infinite slope stability analysis following Morgenstern and Price (1965) is used to define the Factor of Safety and critical conditions for deltaic and lateral slopes, where different triggers can be responsible for the failure. Based on the conducted analysis, static and dynamic stability together with critical failure conditions for different slopes in Lake Lucerne can be compared.</p><p> </p><p>References:</p><p>Hilbe, M. and Anselmetti, F.S. (2015) Mass Movement-Induced Tsunami Hazard on Perialpine Lake Lucerne (Switzerland): Scenarios and Numerical Experiments. Pure and Applied Geophysics 172, 545-568.</p><p>Kremer, K., Simpson, G., Girardclos, S. (2012) Giant Lake Geneva tsunami in AD 563. Nature Geoscience 5, 756-757.</p><p>Morgenstern, N.R. and Price, V.E. (1965) Analysis of stability of general slip surfaces. Geotechnique 15(1): 79–93.</p><p>Schnellmann, M., Anselmetti, F.S., Giardini, D., McKenzie, J.A., Ward, S.N. (2002) Prehistoric earthquake history revealed by lacustrine slump deposits. Geology 30, 1131–1134.</p><p>Strasser, M., Stegmann, S., Bussmann, F., Anselmetti, F.S., Rick, B., Kopf, A. (2007) Quantifying subaqueous slope stability during seismic shaking: Lake Lucerne as model for ocean margins. Marine Geology 240, 77-97.</p>

scholarly journals Comparison between deformation modulus of rock mass measured by plate jacking and dilatometer tests

2017 ◽  
Vol 26 (3) ◽  
pp. 317-325
Author(s):  
Mohsen Rezaei ◽  
Rasoul Ajalloeian ◽  
Mohammad Ghafoori
Keyword(s):  
Rock Mass ◽  
Deformation Modulus ◽  
Rock Masses ◽  
Sarvak Formation ◽  
In Situ Data ◽  
Geotechnical Investigations ◽  
Two Samples ◽  
Dam Site

For determination of the in-situ deformation modulus of rock mass at Bakhtiari Dam site, located in south-west of Iran, plate jacking tests (PJT) and dilatometer tests (DLT) carried out during the geotechnical investigations. In this study, the results of PJTs and DLTs were compared. This comparison involves 89 vertical and horizontal PJTs and 83 DLTs carried out in 6 rock units of Sarvak formation. Although, both PJTs and DLTs in the Bakhtiari Dam site were performed in same geological and geotechnical conditions, but there are not sufficient side by side data to make a paired two samples correlation. Therefore, the mean of in-situ data was compared at each rock unit. Besides Mann–Whitney U tests were performed to compare in-situ test results. The comparison shows that the deformation modulus measured by both methods has no significant differences. However, in low quality rock masses the moduli measured by the use of DLTs were greater than the modulus measured by PJTs. Conversely, in high quality rock masses the results of PJTs were greater than DLT’s.

scholarly journals Stochastic modelling of hydraulic conductivity derived from geotechnical data; an example applied to central Glasgow

2017 ◽  
Vol 108 (2-3) ◽  
pp. 141-154 ◽  
Author(s):  
J. D. O. Williams ◽  
M. R. Dobbs ◽  
A. Kingdon ◽  
R. M. Lark ◽  
J. P. Williamson ◽  
...  
Keyword(s):  
Hydraulic Conductivity ◽  
Mean Squared Error ◽  
Homogeneous Model ◽  
Stochastic Modelling ◽  
Site Investigation ◽  
Process Models ◽  
Spatial Uncertainty ◽  
Conductivity Data ◽  
Geotechnical Investigations

ABSTRACTCharacterising the three-dimensional (3D) distribution of hydraulic conductivity and its variability in the shallow subsurface is fundamental to understanding groundwater behaviour and to developing conceptual and numerical groundwater models to manage the subsurface. However, directly measuring in situ hydraulic conductivity can be difficult and expensive and is rarely carried out with sufficient density in urban environments. In this study we model hydraulic conductivity for 603 sites in the unconsolidated Quaternary deposits underlying Glasgow using particle size distribution and density description widely available from geotechnical investigations. Six different models were applied and the MacDonald formula was found to be most applicable in this heterogeneous environment, comparing well with the few available in situ hydraulic conductivity data. The range of the calculated hydraulic conductivity values between the 5th and 95th percentile was 1.56×10–2–4.38mday–1 with a median of 2.26×10–1 mday–1. These modelled hydraulic conductivity data were used to develop a suite of stochastic 3D simulations conditioned to existing 3D representations of lithology. Ten per cent of the input data were excluded from the modelling process for use in a split-sample validation test, which demonstrated the effectiveness of this approach compared with non-spatial or lithologically unconstrained models. Our spatial model reduces the mean squared error between the estimated and observed values at the excluded data locations over those predicted using a simple homogeneous model by 73 %. The resulting 3D hydraulic conductivity model is of a much higher resolution than would have been possible from using only direct measurements, and will improve understanding of groundwater flow in Glasgow and reduce the spatial uncertainty of hydraulic parameters in groundwater process models. The methodology employed could be replicated in other regions where significant volumes of suitable geotechnical and site investigation data are available to predict ground conditions in areas with complex superficial deposits.

scholarly journals Engineering geological and geotechnical investigations of dam of the Bunakha Hydroelectric Project (180 MW), Chukha Dzong, Bhutan Himalaya

2014 ◽  
Vol 47 (1) ◽  
pp. 77-94 ◽  
Author(s):  
A. K. Naithani ◽  
P. C. Nawani ◽  
L. G. Singh ◽  
D. S. Rawat
Keyword(s):  
Rock Mass ◽  
Shear Zones ◽  
Geological Mapping ◽  
Engineering Properties ◽  
Concrete Gravity Dam ◽  
Hydroelectric Project ◽  
Laboratory Test Results ◽  
Geotechnical Investigations ◽  
Tehri Dam

A 197 m high roller compacted concrete gravity dam is proposed across river Wang Chhu in Chukha Dzong of the Bhutan Himalaya. Bunakha Dam will be the third highest dam constructed by India after the Tehri Dam and Bhakra Dam. The Bunakha Dam site area is located in the Thimpu Formation of the Himalayan crystalline complex. This litho-units at site is characterized by heterogeneous lithology consisting of viz.  banded gneisses, foliated gneisses, with large boudins and bands of quartzite and calc-silicate gneisses with large porphyroblasts of garnet measuring up to 4 mm. These litho units form the foundation of proposed dam. In this paper attempt has been made to bring out the rock mass condition of the foundation of dam of the proposed scheme on the basis of detailed engineering geological mapping, geological logging of drill holes, rock mass permeability values, 3D mapping of exploratory drifts, geophysical profiling, in-situ and laboratory test results. Rock mass classification using Rock Mass Rating (RMR) system and Q-system was done. The basic purpose of these investigations was to identify/map different rocks and structures like joints, shear zones, faults, fracture zones etc. and to determine engineering properties of rock and rock mass by lab and in-situ testing and to provide basic data for economic and fail-safe design of the dam. On the basis of these investigations suitable recommendations have been made which will be helpful during the construction of the dam. 

Cone penetration testing in stiff glacial soils using a downhole cone penetrometer

1992 ◽  
Vol 29 (3) ◽  
pp. 448-455
Author(s):  
Curtis R. Treen ◽  
Peter K. Robertson ◽  
David J. Woeller
Keyword(s):  
Penetration Resistance ◽  
Standard Penetration Test ◽  
Cone Penetrometer ◽  
Penetration Test ◽  
Cone Penetration ◽  
Penetration Testing ◽  
Cone Penetration Testing ◽  
Geotechnical Investigations ◽  
Drilling Rigs

Cone penetration testing (CPT) in Canada is usually performed using locally available drilling rigs. The limited pushing capacity of most drilling rigs coupled with the risk of damage to expensive cone penetrometers has tended to restrict the CPT to generally loose or soft soils. Therefore, in regions dominated by stiff glacial soils the more rugged standard penetration test (SPT) is still the most commonly used in situ test during geotechnical investigations. However, there are many limitations with the SPT with respect to interpretation and repeatability, especially the uncertainty with the energy delivered from various SPT hammer anvil systems. A downhole cone penetration test (DCPT) has been developed by modifying the equipment and procedure of the standard electric CPT. The DCPT consists of a simple, inexpensive electric cone penetrometer attached to a 1.5 m (5 ft) length of AW drill rod. The test is performed by pushing the cone 1.5 m into the base of an open borehole to produce a continuous profile of penetration resistance Qc, over the 1.5-m interval or whatever interval penetration is possible. The test incorporates the simplicity, ruggedness, and depth capability of the SPT but is able to define a near-continuous, accurate, and repeatable cone penetration resistance profile. The equipment and procedure of the DCPT is described in detail, and results from a near-continuous DCPT and an adjacent continuous CPT are presented and compared with the results obtained from an adjacent borehole with SPT. Excellent agreement was found between the results of the DCPT and the CPT. Key words : in situ, cone penetration testing, stiff soils.

scholarly journals Statistical Time-Series Analysis of Interferometric Coherence from Sentinel-1 Sensors for Landslide Detection and Early Warning

Sensors ◽  
2021 ◽  
Vol 21 (20) ◽  
pp. 6799
Author(s):  
Marios Tzouvaras
Keyword(s):  
Time Series ◽  
Early Warning ◽  
Statistical Significance ◽  
Early Warning Systems ◽  
Time Of Day ◽  
Landslide Occurrence ◽  
Geotechnical Investigations ◽  
Wide Range ◽  
Sar Imagery

Landslides are one of the most destructive natural hazards worldwide, affecting greatly built-up areas and critical infrastructure, causing loss of human lives, injuries, destruction of properties, and disturbance in everyday commute. Traditionally, landslides are monitored through time consuming and costly in situ geotechnical investigations and a wide range of conventional means, such as inclinometers and boreholes. Earth Observation and the exploitation of the freely available Copernicus datasets, and especially Sentinel-1 Synthetic Aperture Radar (SAR) images, can assist in the systematic monitoring of landslides, irrespective of weather conditions and time of day, overcoming the restrictions arising from in situ measurements. In the present study, a comprehensive statistical analysis of coherence obtained through processing of a time-series of Sentinel-1 SAR imagery was carried out to investigate and detect early indications of a landslide that took place in Cyprus on 15 February 2019. The application of the proposed methodology led to the detection of a sudden coherence loss prior to the landslide occurrence that can be used as input to Early Warning Systems, giving valuable on-time information about an upcoming landslide to emergency response authorities and the public, saving numerous lives. The statistical significance of the results was tested using Analysis of Variance (ANOVA) tests and two-tailed t-tests.

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