Equipment and techniques for offshore survey and site investigations

1981 ◽  
Vol 18 (2) ◽  
pp. 230-249 ◽  
Author(s):  
P. G. Sly
Keyword(s):  
Physical And Mechanical Properties ◽  
Deep Ocean ◽  
Site Investigation ◽  
Remotely Sensed Data ◽  
In Situ Tests ◽  
Field Surveys ◽  
The Past ◽  
Site Investigations ◽  
Sample Recovery

This contribution presents a recent review of equipment and field techniques applicable to offshore seabed survey work and site investigation, with particular reference to Canadian interests.During the past decade many advances have taken place in equipment design and in under standing the behaviour of mechanical sampling devices and the inadequacies of data derived from samples physically removed from the site. There has been a significant improvement in the ability of both remote and contact sensory systems to characterize and resolve differences in the physical and mechanical properties of bottom sediment materials, and the use of even simplistic remotely sensed data, if rapidly obtained and processed, offers significant economic advantages. The trend towards greater use of in situ tests will continue.The application of facies concepts, in planning field surveys, may provide opportunities for improved sample recovery, reduced sampling, and greater confidence in data interpretation.Data, comments, and examples refer to a number of Canadian situations, for example, deep ocean studies, shelf studies (such as on the Labrador Shelf, the Scotian Shelf, and the Beaufort Sea), inter-island studies in the Canadian Arctic, and inland studies in the Great Lakes and smaller lake and river systems.

Interpretation of overconsolidation ratio from in situ tests in Recent clay deposits in Singapore and Malaysia

1991 ◽  
Vol 28 (2) ◽  
pp. 210-225 ◽  
Author(s):  
M. F. Chang
Keyword(s):  
Site Investigation ◽  
Test Methods ◽  
In Situ Tests ◽  
Stress History ◽  
Overconsolidation Ratio ◽  
Clay Deposits ◽  
Preconsolidation Pressure ◽  
Pressure Stress ◽  
Sample Disturbance

The stress history as indicated by the profile of overconsolidation ratio (OCR) of a soil deposit is one of the most dominant factors that influence the engineering behaviour of the soil. Its assessment, which is traditionally based on the laboratory oedometer test, is not often satisfactory. The problem arises from inevitable sample disturbance and the high cost of a detailed investigation. These difficulties can be overcome by the use of in situ tests. The field vane test, the piezocone test, and the dilatometer test are three such methods that provide indirect means for the estimation of the OCR for clay deposits. A number of empirical correlations are available for this purpose. Calibration of these correlations against results of site investigation in Singapore and Malaysian marine clays reveals the usefulness of these test methods in profiling the OCR for Recent clay deposits. Key words: clay, in situ test, overconsolidation ratio, preconsolidation pressure, stress history.

Design Criteria for a New Weir Surface Repair Method Containing Shock Absorbing Cushions

2011 ◽  
Author(s):  
Tse-Shan Hsu ◽  
Yi-Lang Hsieh
Keyword(s):  
Surface Layer ◽  
Material Properties ◽  
Design Criteria ◽  
In Situ Tests ◽  
The Past ◽  
Repair Materials ◽  
Resistant Layer ◽  
Related Test ◽  
Surface Repair

Although a weir surface layer is subjected to shocks of the floods with particles of varies sizes, they are generally repaired by covering an abrasion-resistant layer. In the past, based on the knowledge that higher strength materials have higher abrasion resistances, many reports have focused on enhancing the strength of the repair materials. However, the occurrence of brittle fracture and peeling were also significantly increased. These resulted in an awkward situation that the need of repairing becomes more urgent even if the material properties have been greatly improved. In an attempt to break through the traditional methods, the major thrust of this paper is to propose criteria for designing a weir surface containing shock absorbing cushions, and a new method accordingly.. It was then confirmed by in situ tests that such criteria have the capability to lead the above-mentioned shocks to be absorbed. Due to the limited space of this paper, all related test layout and results will be presented on another paper.

Introduction to geotechnical analysis, site investigation and in-situ tests

2021 ◽  
pp. 1-80
Author(s):  
Yung Ming Cheng ◽  
Chi Wai Law ◽  
Leilei Liu
Keyword(s):  
Site Investigation ◽  
In Situ Tests

The evolution of Montebestia landslide (Umbria, Central Italy). Site investigations, in-situ tests and GPS monitoring

2000 ◽  
Vol 25 (9) ◽  
pp. 799-808 ◽  
Author(s):  
C. Cencetti ◽  
P. Conversini ◽  
F. Radicioni ◽  
C. Ribaldi ◽  
S. Selli ◽  
...  
Keyword(s):  
Central Italy ◽  
In Situ Tests ◽  
Site Investigations ◽  
Gps Monitoring

Analysis of self-boring pressuremeter (SBPM) and Marchetti dilatometer (DMT) tests in granite saprolites

2000 ◽  
Vol 37 (4) ◽  
pp. 796-810 ◽  
Author(s):  
F Schnaid ◽  
J AR Ortigao ◽  
F M Mántaras ◽  
R P Cunha ◽  
I MacGregor
Keyword(s):  
Site Investigation ◽  
Friction Angle ◽  
Soil Parameters ◽  
Residual Soil ◽  
Residual Soils ◽  
In Situ Tests ◽  
Cemented Sand ◽  
Fundamental Parameters ◽  
Analysis Technique

This paper presents the analyses of the results of the site investigation programme carried out at the Kowloon Bay site in Hong Kong. The tests consisted of self-boring pressuremeter (SBPM), Marchetti dilatometer (DMT), and laboratory tests carried out in a granite saprolite, which can be described as a lightly cemented sand. The purpose of this research project is to stimulate the development of methods to interpret data obtained from tests in residual soils. In particular, the work aims to evaluate the analyses of the SBPM data through a curve-fitting technique. Both the loading and unloading portions of the SBPM curve were analysed and the results compared with those from other tests. The advantage of this analysis technique is the possibility of constructing a theoretical curve that reproduces a pressuremeter test from which a set of fundamental parameters can be derived, namely the friction angle, cohesion intercept, lateral stress, and shear modulus. The DMT proved to be a reliable tool that yielded good soil parameters at a small fraction of the cost of the other in situ tests.Key words: residual soil, in situ tests, pressuremeter, Marchetti dilatometer.

scholarly journals Predicting the bearing capacity of pile installed into cohesive soil concerning the spatial variability of SPT data (A case study)

2021 ◽  
Vol 11 (1) ◽  
pp. 45-64
Author(s):  
Duong Hong Tham ◽  
Truong Nhu Manh
Keyword(s):  
Bearing Capacity ◽  
Static Load ◽  
Physical And Mechanical Properties ◽  
Cohesive Soil ◽  
Load Test ◽  
Penetration Test ◽  
Static Load Test ◽  
In Situ Tests ◽  
Spt Data

Nowadays, in situ tests have played a viable role in geotechnical engineering and construction technology. Besides lab tests conducted on undisturbed soil samples, many different kinds of in-situ tests were used and proved to be more efficient in foundation design such as pressuremeter PMT, cone penetration test CPT, standard SPT, etc. Among them, a standard penetration test (SPT for short) is easy to carry out at the site. For decades, it has proved reliable to sandy soil, but many viewpoints and opinions argued that the test was not appropriately applicable to cohesive soil because of scattered and dispersed data of SPT blow counts through different layers. This paper firstly studies how reliable the SPT data can predict the physical and mechanical properties; secondly, the soil strength is determined in terms of corrected N-SPT values, and finally the bearing capacity of a pile penetrating cohesion soil. By analyzing data from 40 boreholes located in 18 projects in Ho Chi Minh City, South VietNam, coefficients of determination between SPT numbers and physical and mechanical properties of different soil kinds are not the same: R2 = 0.623 for sand, =0.363 for sandy clay and =0.189 for clay. The spatial variability of soil properties is taken into account by calculating the scale of fluctuation θ=4.65m beside the statistically-based data in horizontal directions. Finally, the results from two theoretical approaches of predicting pile bearing capacity were compared to those of finite element program Plaxis 3D and static load test at site. Correlation between the capacity computed by using corrected N-values instead of soil strength and results of static load test has proved to be well suitable in evaluating the bearing capacity of driven and jack-in piles, particularly installing in the cohesive soil using the SPT blows.

Site investigation and in situ tests

1994 ◽  
pp. 379-399
Author(s):  
C. R. Scott
Keyword(s):  
Site Investigation ◽  
In Situ Tests

scholarly journals Predicting Liquefaction in Near-Real-Time (NRT): An Assessment of Geospatial vs. Geotechnical Models During the Canterbury Earthquakes

2017 ◽  
Author(s):  
Brett Maurer
Keyword(s):  
Real Time ◽  
Common Ground ◽  
Cyclic Stress ◽  
Soil Liquefaction ◽  
Remotely Sensed Data ◽  
In Situ Tests ◽  
Intensity Measures ◽  
Geotechnical Tests ◽  
Semi Empirical

Semi-empirical models based on in-situ geotechnical tests have become the standardof practice for predicting soil liquefaction. Since the inception of the “simplified”cyclic-stress model in 1971, variants based on various in-situ tests have beendeveloped, including the Cone Penetration Test (CPT). More recently, predictionmodels based soley on remotely-sensed data were developed. Similar to systemsthat provide automated content on earthquake impacts, these “geospatial” modelsaim to predict liquefaction for rapid response and loss estimation using readilyavailabledata. This data includes (i) common ground-motion intensity measures(e.g., PGA), which can either be provided in near-real-time following an earthquake,or predicted for a future event; and (ii) geospatial parameters derived from digitalelevation models, which are used to infer characteristics of the subsurface releventto liquefaction. However, the predictive capabilities of geospatial and geotechnicalmodels have not been directly compared, which could elucidate techniques forimproving the geospatial models, and which would provide a baseline for measuringimprovements. Accordingly, this study assesses the realtive efficacy of liquefactionmodels based on geospatial vs. CPT data using 9,908 case-studies from the 2010-2016 Canterbury earthquakes. While the top-performing models are CPT-based, thegeospatial models perform relatively well given their simplicity and low cost.Although further research is needed (e.g., to improve upon the performance ofcurrent models), the findings of this study suggest that geospatial models have thepotential to provide valuable first-order predictions of liquefaction occurence andconsequence. Towards this end, performance assessments of geospatial vs.geotechnical models are ongoing for more than 20 additional global earthquakes

scholarly journals Distribution, population structure, and management of a rare sandalwood (Santalum yasi, Santalaceae) in Fiji and Tonga

2015 ◽  
Vol 21 (1) ◽  
pp. 27 ◽  
Author(s):  
Ryan D. Huish ◽  
Tevita Faka'osi ◽  
Heimuli Likiafu ◽  
Joseva Mateboto ◽  
Katherine H. Huish
Keyword(s):  
Population Data ◽  
Size Class ◽  
Natural Distribution ◽  
Field Surveys ◽  
The Past ◽  
Adaptive Comanagement ◽  
Adult Trees ◽  
In The Wild ◽  
Study Sites

The aromatic heartwood of Santalum yasi has been harvested extensively in Fiji and Tonga over the past two centuries for international trade in the medicinal, perfume, and incense industry and other cultural purposes. Field surveys and a review of historic and modern documents reveal a sparse and scattered distribution and indicate that the natural distribution of S. yasi has fluctuated over time, even declining to local extinction in the wild in some areas, while S. album has been introduced and naturalisation of S. yasi × S. album hybrids is evident. Population data collected along transects in three in situ S. yasi populations show discontinuous size-class structures, indicating regenerative stress. The population densities at study sites ranged from 19 to 63 adult trees (≥5 cm dbh) per hectare and less than two heartwood-bearing trees (≥15 cm dbh) per hectare. Though S. yasi trees may attain up to 40 cm dbh, no trees greater than 23 cm dbh were found in any of the studied populations. Low density and small size of adult trees and human-induced bole damage are suggestive of frequent, premature, and defensive harvesting patterns and indicate the need for ongoing adaptive comanagement in recognition of underlying economic and sociocultural pressures.

Deep-seated consolidation settlements in the Fraser River delta

1991 ◽  
Vol 28 (2) ◽  
pp. 298-303 ◽  
Author(s):  
C. B. Crawford ◽  
N. R. McCammon ◽  
R. C. Butler
Keyword(s):  
River Delta ◽  
Fraser River ◽  
In Situ Tests ◽  
Case Record ◽  
The Past ◽  
Undisturbed Samples ◽  
Consolidation Settlement ◽  
Fraser River Delta ◽  
Heavy Loads

This paper describes the settlements of three heavy silo structures at two cement plants located along the south arm of the Fraser River delta. In this area, it has not been possible to obtain sufficiently undisturbed samples for reliable consolidation tests, and it has been necessary therefore to employ in situ tests and site improvement techniques such as preloading and vibrocompaction for the design of foundations. In some cases, piles were used to redistribute heavy loads. Observations during the past 35 years have shown that most of the consolidation settlement has occurred in a deep layer of marine sediments and that it is largely completed within 10 years of the loading. Key words: case record, consolidation, foundation performance, in situ tests, preloading, settlements, site improvement.

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