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

1992 ◽  
Vol 29 (1) ◽  
pp. A31
Keyword(s):  
In Situ Tests ◽  
Overconsolidation Ratio ◽  
Clay Deposits

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.

scholarly journals The overconsolidation ratio of eemian gyttja determination

2017 ◽  
Vol 49 (3) ◽  
pp. 213-221
Author(s):  
Marek Bajda ◽  
Edyta E. Malinowska
Keyword(s):  
Laboratory Tests ◽  
Geotechnical Engineering ◽  
Soft Soil ◽  
Foundation Engineering ◽  
Soil Behavior ◽  
In Situ Tests ◽  
Stress History ◽  
Overconsolidation Ratio ◽  
In Situ Conditions

Abstract The overconsolidation ratio of eemian gyttja determination. The overconsolidation ratio is an important parameter that determines the value of stress history exerted in the past on the subsoil in the geotechnical engineering. Overconsolidation ratio (OCR) is one of the main criteria conditioning soil behavior and characteristics. To know the relation between geological background, history and mechanical behavior of the soil, aims a knowledge that can help engineers who often have to predict soil behavior based upon the soil geological history and a geotechnical data. In order to evaluate the overconsolidation ratio of eemian gyttja, it is necessary to restore this soft soil as much as possible to the in situ conditions. The eemian gyttja is an organic soft soil from the “Zoliborz channel” located in Warsaw. These soils are used as a base construction in the foundation engineering. In practical geotechnical engineering, evaluation of stress history is based on the overconsolidation ratio. The overconsolidation ratio is one of the basic parameters for the geotechnical design of the structure. Determination of this parameter using for example dilatometer tests, is usually based on empirical formulas which were established in different countries. Therefore, regional geotechnical conditions could have substantially affected on the empirical relationships. The laboratory tests are used to determinate the preconsolidation pressure and then the overconsolidation ratio. The laboratory tests were made in the automatic oedometer and the in situ tests were carried out on the dilatometer test (DMT). The paper presents results of determination the overconsolidation ratio of eemian gyttja from the laboratory and in situ tests. The studies have shown that the values of the overconsolidation ratio determination from the laboratory tests are a little higher than determination from the in situ tests.

scholarly journals Experimental and CFD Simulations of the Aerosol Flow in the Air Ventilating the Underground Excavation in Terms of SARS-CoV-2 Transmission

Energies ◽  
2021 ◽  
Vol 14 (16) ◽  
pp. 4743
Author(s):  
Tomasz Janoszek ◽  
Zbigniew Lubosik ◽  
Lucjan Świerczek ◽  
Andrzej Walentek ◽  
Jerzy Jaroszewicz
Keyword(s):  
Numerical Calculations ◽  
Mining Institute ◽  
Ventilation Network ◽  
Underground Excavation ◽  
In Situ Tests ◽  
Ansys Fluent ◽  
Aerosol Emission ◽  
Ansys Cfx ◽  
Computational Fluid Dynamics Cfd

The paper presents the results of experimental and model tests of transport of dispersed fluid droplets forming a cloud of aerosol in a stream of air ventilating a selected section of the underground excavation. The excavation selected for testing is part of the ventilation network of the Experimental Mine Barbara of the Central Mining Institute. For given environmental conditions, such as temperature, pressure, relative humidity, and velocity of air, the distribution of aerosol droplet changes in the mixture of air and water vapor along the excavation at a distance was measured at 10 m, 25 m, and 50 m from the source of its emission. The source of aerosol emission in the excavation space was a water nozzle that was located 25 m from the inlet (inlet) of the excavation. The obtained results of in situ tests were related to the results of numerical calculations using computational fluid dynamics (CFD). Numerical calculations were performed using Ansys-Fluent and Ansys-CFX software. The dimensions and geometry of the excavation under investigation are presented. The authors describe the adopted assumptions and conditions for the numerical model and discuss the results of the numerical solution.

scholarly journals Experimental Evaluation of Shear Behavior of Stone Masonry Wall

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2313
Author(s):  
Maria Luisa Beconcini ◽  
Pietro Croce ◽  
Paolo Formichi ◽  
Filippo Landi ◽  
Benedetta Puccini
Keyword(s):  
Shear Behavior ◽  
Stone Masonry ◽  
Masonry Walls ◽  
Mechanical Parameters ◽  
In Situ Tests ◽  
Capacity Curves ◽  
Historical Structures ◽  
Definition Of

The evaluation of the shear behavior of masonry walls is a first fundamental step for the assessment of existing masonry structures in seismic zones. However, due to the complexity of modelling experimental behavior and the wide variety of masonry types characterizing historical structures, the definition of masonry’s mechanical behavior is still a critical issue. Since the possibility to perform in situ tests is very limited and often conflicting with the needs of preservation, the characterization of shear masonry behavior is generally based on reference values of mechanical properties provided in modern structural codes for recurrent masonry categories. In the paper, a combined test procedure for the experimental characterization of masonry mechanical parameters and the assessment of the shear behavior of masonry walls is presented together with the experimental results obtained on three stone masonry walls. The procedure consists of a combination of three different in situ tests to be performed on the investigated wall. First, a single flat jack test is executed to derive the normal compressive stress acting on the wall. Then a double flat jack test is carried out to estimate the elastic modulus. Finally, the proposed shear test is performed to derive the capacity curve and to estimate the shear modulus and the shear strength. The first results obtained in the experimental campaign carried out by the authors confirm the capability of the proposed methodology to assess the masonry mechanical parameters, reducing the uncertainty affecting the definition of capacity curves of walls and consequently the evaluation of seismic vulnerability of the investigated buildings.

scholarly journals Digital Image Correlation for Evaluation of Cracks in Reinforced Concrete Bridge Slabs

2021 ◽  
Vol 6 (7) ◽  
pp. 99
Author(s):  
Christian Overgaard Christensen ◽  
Jacob Wittrup Schmidt ◽  
Philip Skov Halding ◽  
Medha Kapoor ◽  
Per Goltermann
Keyword(s):  
Reinforced Concrete ◽  
Digital Image Correlation ◽  
Crack Initiation ◽  
Laboratory Test ◽  
Digital Image ◽  
Crack Detection ◽  
Image Correlation ◽  
In Situ Tests ◽  
Stop Criterion

In proof-loading of concrete slab bridges, advanced monitoring methods are required for identification of stop criteria. In this study, Two-Dimensional Digital Image Correlation (2D DIC) is investigated as one of the governing measurement methods for crack detection and evaluation. The investigations are deemed to provide valuable information about DIC capabilities under different environmental conditions and to evaluate the capabilities in relation to stop criterion verifications. Three Overturned T-beam (OT) Reinforced Concrete (RC) slabs are used for the assessment. Of these, two are in situ strips (0.55 × 3.6 × 9.0 m) cut from a full-scale OT-slab bridge with a span of 9 m and one is a downscaled slab tested under laboratory conditions (0.37 × 1.7 × 8.4 m). The 2D DIC results includes full-field plots, investigation of the time of crack detection and monitoring of crack widths. Grey-level transformation was used for the in situ tests to ensure sufficient readability and results comparable to the laboratory test. Crack initiation for the laboratory test (with speckle pattern) and in situ tests (plain concrete surface) were detected at intervals of approximately 0.1 mm to 0.3 mm and 0.2 mm to 0.3 mm, respectively. Consequently, the paper evaluates a more qualitative approach to DIC test results, where crack indications and crack detection can be used as a stop criterion. It was furthermore identified that crack initiation was reached at high load levels, implying the importance of a target load.

Effects of corrosion on a steel bowstring bridge in marine environment: A case-study of assessment and retrofit

2021 ◽  
Vol 16 (4) ◽  
pp. 121-137
Author(s):  
Michele Fabio Granata
Keyword(s):  
Corrosion Protection ◽  
Marine Environment ◽  
Spray Coating ◽  
Thermal Spray Coating ◽  
In Situ Tests ◽  
Limit States ◽  
Intervention Measures ◽  
Near Future

The case-study of a steel bowstring bridge set in a marine environment and highly damaged by corrosion is presented. The bridge was built in 2004 and was repainted for corrosion protection in 2010. Despite the recent construction and the maintenance interventions, many structural elements like hangers are highly damaged by corrosion with decreasing performance in terms of serviceability and ultimate limit states. A deep investigation was carried out in order to assess the bridge and to establish the necessary retrofit actions to be carried out in the near future. In-situ tests reveal the reduced performance of the original steel in terms of strength and corrosion protection, together with the inefficiency of the successive maintenance interventions. The paper presents assessment of the bridge and retrofit measures, including replacement of the hangers and galvanization through thermal spray coating technology, in order to increase its service life. The results of the investigations and the intervention measures are outlined and discussed.

scholarly journals Laboratory and In Situ Determination of Hydraulic Conductivity and Their Validity in Transient Seepage Analysis

Water ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1131
Author(s):  
Soonkie Nam ◽  
Marte Gutierrez ◽  
Panayiotis Diplas ◽  
John Petrie
Keyword(s):  
Hydraulic Conductivity ◽  
Field Measurements ◽  
Natural Soil ◽  
In Situ Tests ◽  
Seepage Analysis ◽  
Soil Deposits ◽  
Seepage Modeling ◽  
Sample Disturbance

This paper critically compares the use of laboratory tests against in situ tests combined with numerical seepage modeling to determine the hydraulic conductivity of natural soil deposits. Laboratory determination of hydraulic conductivity used the constant head permeability and oedometer tests on undisturbed Shelby tube and block soil samples. The auger hole method and Guelph permeameter tests were performed in the field. Groundwater table elevations in natural soil deposits with different hydraulic conductivity values were predicted using finite element seepage modeling and compared with field measurements to assess the various test results. Hydraulic conductivity values obtained by the auger hole method provide predictions that best match the groundwater table’s observed location at the field site. This observation indicates that hydraulic conductivity determined by the in situ test represents the actual conditions in the field better than that determined in a laboratory setting. The differences between the laboratory and in situ hydraulic conductivity values can be attributed to factors such as sample disturbance, soil anisotropy, fissures and cracks, and soil structure in addition to the conceptual and procedural differences in testing methods and effects of sample size.

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