g.frunza_l.batali_evaluation of hydraulic properties of soils. correlations between

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  • First International Conference for PhD students in Civil Engineering

    CE-PhD 2012, 4-7 November 2012,Cluj-Napoca, Romania www.sens-group.ro/ce2012

    Evaluation of hydraulic properties of soils. Correlations between

    different methods. Application for Bucharest area.

    Georgiana Sorina Frunz1, Loretta Batali2

    1,2 Technical University of Civil Engineering Bucharest, Faculty of Hydraulic Works, 124 Boul.

    Lacul Tei, sector 2, 020396 Bucharest, Romania

    Abstract

    There are numerous methods for determining hydraulic conductivity of soils: laboratory methods,

    in situ tests or methods based on empirical correlations with other physical parameters of the soil.

    Hydraulic conductivity is a very sensitive parameter to several factors, which lead to large

    differences between the values obtained using different methods.

    When a hydro-geological database is to be developed, one of the main problems to be solved is to

    interpret and integrate hydraulic conductivity values which were obtained by various authors and

    through different methods.

    Paper presents part of a research conducted in the framework of SIMPA project Platform for management of sedimentary groundwater in urban areas financed by ANCS. This part of the research aims to define the hydro-geological database to be introduced in the GIS platform.

    Comparisons are made between the values determined by different methods, based on which it will

    be possible to determine reliable values of the hydraulic conductivity to be used by the GIS

    platform.

    Keywords: soil, groundwater, empirical correlations, permeability

    1. Introduction

    Urban groundwater is a risk environment considering both sensitivity and multiple influence

    factors that arise in such environment. Their correct management is a relatively difficult task to

    accomplish, especially in an area of increased urban development and, in some aspects even

    chaotic, as the capital.

    Project SIMPA "Platform for the management of sedimentary groundwater in urban areas "

    initiated by UTCB, including also the present study, represents an important step in this direction,

    its aim being to develop a GIS data platform for managing the existin data. .

    Platform for the management of sedimentary groundwater in urban areas - SIMPA proposes

    carrying out hydrogeological resources management in Bucharest area, which contributes to a better

    geological, geotechnical and hydrogeological knowledge of the Moesic aquifer system, in order to

    achieve a better management of it.

    The area chosen for study, as also in other areas of the country, there is very little control

    over the work performed underground or work of investigation and exploitation of water resources.

    This leads to difficulties of management, but also to problems of interpretation of new

    investigations due to unknown interactions that may be present. In view of the large amount of

    investigations carried out in the area around Bucharest, there is a large quantity of information

    related to ground and aquifer structure, without, however, being organized and structured.

  • First International Conference for PhD students in Civil Engineering

    CE-PhD 2012, 4-7 November 2012,Cluj-Napoca, Romania www.sens-group.ro/ce2012

    Having a management platform that provides information on everything that underground

    environment in this area means is very useful for all actors in the field: authorities, designers,

    building companies, etc..Also, such a platform will provide opportunities for more detailed study

    when you want building a new underground construction, in order to take into account as many

    possible interactions.

    In this context, one of the steps is the proper characterization of geological layers by

    hydrogeological and geotechnical parameters. For this purpose we used historical data and special

    studies were conducted to characterize in terms of permeability coefficient, given that this is a very

    sensitive parameter and that different methods for its determining lead to very different results.

    Based on these studies will be assigned a correct value of the permeability coefficient for each

    layer.

    Also, based on different single values, an extrapolation is necessary and spatial extent of the

    values to the entire volume of soil, the required tools being included on this platform

    The paper presents aspects related to the permeability coefficient assessment through

    different methods, with application to Bucharest area.

    2. Determination of the coefficient of permeability

    2.1. Test Methods

    At present, the issues related to the groundwater movement are treated by geologists, hydro-

    geologists, geotechniciens, pedologists etc, each and every one of these Communities having

    developed their own methods for measuring the permeability coefficient. This proliferation of the

    methods has as result that engineers are in the face of such delicate choices to find the proper

    method to solve the problem being studied, choices which are often uninspired or even wrong.

    Permeability coefficient can be determined in situ, in the laboratory or oby using

    correlations with physical soil parameters, for each of these categories existing a large variety of

    methods which are the subject of research and improvement even at present (even if many methods

    are applied by many years).

    Regarding the in situ and laboratory methods for determination of the permeability

    coefficient, the main classification of problems and methods refers to the saturation, saturated or

    unsaturated environment, respectively. In this paper we refer in particular to saturated enviroments.

    Among the methods for the determination in laboratory can be mentioned:

    - Permeametres with flexible or rigid walls - Permeametres with or without normal stress - Permeametres - with or without suction - Permeametres - with constant or variable head Among the in situ methods the most used are:

    - Experimental pumping test - steady or transient - Flow velocity measurement using tracers - Measurements in auger holes and boreholes - Piezometer method - Piezocone method (CPTu) - Experimental water pouring (Boldarev-Nesterov) - Drain line method - Method Lefranc - Method Brillant - Lysimeters

    Correlations between different soil parameters is a semi-empirical or empirical method for

  • First International Conference for PhD students in Civil Engineering

    CE-PhD 2012, 4-7 November 2012,Cluj-Napoca, Romania www.sens-group.ro/ce2012

    determining some parameters, including the permeability coefficient, that is much appreciated

    by engineers, as in this case investigations are limited to a minimum and the literature abounds

    in such relationships. It should be noted however, that their use is limited to certain soil types,

    possibly to certain specific conditions and cannot be used in any manner whatsoever without

    control over the results (differences, as will be shown later, being significant).

    2.2 Selection of the determination method

    When it comes to determining the soil permeability more questions can be raised:

    - Which is the nature of the parameter to be measured - ksat, kunsat,, for example? - How it should be properly measured - in the laboratory, on the field? - Which should be the test duration? - Where should the measurement be performed? the ground is not homogeneous - How many measurements should be conducted to obtain a representative value?- Role of

    geostatistics

    - What means are available? The following figure presents a summary of methods for determining the permeability that can

    provide elements for choosing the optimal method (Figure 1, after Chossat, 2005).

    Figure 1. Method for determinining the permeability coefficient in saturated environments (after

    Chossat, 2005)

    Determination of hydraulic conductivity in

    saturated environment

    Laboratory tests Empirical methods

    Constant head

    -cylinder

    -permeameter

    -triaxial

    -centrifuge

    Variable head

    -cylinder

    -centrifuge

    - Hazen

    - Alyamani & Sen

    - Slichter

    - Beyer

    - Chapuis

    - Kruger

    - Kozeni

    - Puckett et al

    - Raawls & Brakensiek

    - Shepard

    - Sperry & Peirce

    - Terzaghi

    - Zamarin

    - Zunker

    - USRIn situ tests

    In the saturated area In the unsaturated area

    In the saturated area

    -piezometer

    -tube method

    -piezocone

    -Pulse test

    -Slug test

    -Mini-slug test

    -Drain line method

    -Borehole

    -Lefranc

    -Multiple wells

    -Pumping test

    -Lugeon method

    -WD-test

    -Open tube method

    -Dipole flow test

    -Infiltrometers under pressure

    simple infiltrometers open or

    closed ring

    double infiltrometers open or

    closed ring

    Guelph infiltrometer

    Infiltration rate

    Two tubes method

    -Infiltrometers in suction

    Multidisc method

    Minidisc method

    -Guelph permeameter

    -Boutwell method

    -Nasberg method

    -Porchet method

    -Lefranc method

    -Matsuo method

    -Saturated spot test

    -Shani method

  • First International Conference for PhD students in Civil Engineering

    CE-PhD 2012, 4-7 November 2012,Cluj-Napoca, Romania www.sens-group.ro/ce2012

    In this analysis of methods for determining the permeability coefficient other parameters should

    also

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