Abstract:The paper presents complex analyses of geophysical site investigation results. The electrical resistivity method was used to investigate the potential pollutant migration pathways within areas of existing and former landfill sites. For the purpose of the present study, there were four municipal waste landfills and one industrial landfill chosen for further comprehensive analyses. The landfill bottom was isolated using geomembrane liner. However, ground water monitoring results revealed that the base was not leakage-free. Another two landfills were established in the past, when no containment systems were legally required. The geoelectrical investigation was the final part of an overall analytical assessment of the contaminated sites. The study was aimed at pollution spatial migration analyses and the interpretation of results, for further design of the reclamation and restoration plans. A clear correlation between pollution indicators such as salt compounds and electrical resistivity, allow aerial analyses and the precise determination of contaminated zones. The research results presented in the paper have been recently obtained and concern a period from 2010 to 2015.

Nowoursynowska 159, Abstract. Soil electrical conductivity measurements are uniquely useful for environmental impact assessment. Both surface and downhole methods may be used to monitor groundwater and soil quality. This paper presents a site investigation that was conducted to characterize soil and groundwater quality in the Imielin countryside in Poland, where traditional and precision farming have been applied. Two methods for estimating the salinity of soils were used: electrical resistivity tomography (ERT) and the EC-Probe for direct measurement of ground salinity. Based on electrical conductivity measurements, several maps of electrical conductivity zones were produced to assess groundwater and soil quality on agricultural land. Moreover, the empirical relationship between total dissolved solids (TDS) in water vs. soil electrical conductivity (EC), moisture and fine particle content was obtained. The two different techniques that were used in this study to measure the electrical conductivity of soil showed comparable test results and demonstrated that the investigated area is not contaminated.

Standard test methods may not be suitable or sufficient for determining the geotechnical conditions of a structure’s subsoil and the effects of the designed structures on the environment. Geophysical test methods, validated with other methods, may prove useful. In recent years they have found many new applications in engineering practice, both geotechnical and environmental. The advantages of geophysical methods include the non-destructive and non-invasive nature of the tests, their low costs and quick results, as well as compatibility with different materials, including soils, solid rocks, wastes and anthropogenic formations. The paper presents the analysis of laboratory and field investigations including research in a modified oedometer, resistivity chamber, electrical resistivity tomography (ERT) and resistivity cone penetration test (RCPT). Laboratory tests allowed for the assessment of the degree of saturation and porosity of sandy and clayey soils. The tests were carried out on saturated and unsaturated soil samples and allowed for the determination of some relationships between electrical conductivity and porosity. The proposed equations were used to assess parameters in in situ studies using RCPT tests and showed good agreement with reference values based on undisturbed soil samples. ERT tests confirmed the usefulness of electrical measurements in the quality assurance of subsoil and hydrotechnical structures. The tests showed weakening zones in the levee body, discontinuity of the vertical sealing system on the modernized section of the embankment, and location of the top of clay deposits.

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Various types of trenchless methods are extensively used to create engineering barriers for the purpose of achieving relatively low hydraulic conductivity of the subsoil and hydrotechnical structures. The most commonly used technologies of the grouting curtain creating are the DSM (Deep Soil Mixing), WIPS (Vibro Injcted Thin Wall), low-pressure injection and jet-grouting. Vertical barriers are widely used in environmental control systems to restrict the lateral spreading of liquid or gaseous contaminants and for seepage control through and beneath a levees. The barrier walls are constructed in a single or two phases using a slurry composed mainly of bentonite, cementitious materials and water. Often to solve complex geotechnical problems the technologies are combined (e.g. combining DSM and jet grouting). In the paper some examples of practical application of chosen types of technology dedicated different problems solving are presented. The results of geotechnical investigations of hydraulic permeability, shear strength and depth control of cut-off wall are given. The tests were carried out using BAT system, Cone Penetration Tests (CPT) and drillings. The presented test results should help define the technical and financial criteria that should be used to compare grouting based methods and other techniques applicable to the same geotechnical special works. These recommendations should permit an adequate application of grouting techniques and contribute to finding solutions for the delicate problem of ground sealing, notably when proceeding with hydrotechnical or environmental structures placed below water table.

Abstract:The use of resistivity and seismic cone penetration tests for site characterization. Recent application of cone penetration tests to geotechnical and environmental site characterization has generated a wide collection of new sensors. This paper presents methods of interpreting geotechnical in situ investigations carried out by electrical resistivity (RCPT) and seismic (SCPT) cones. It contains some fundamental equations and the description of in situ electrical resistivity and shear wave velocity measurements and presents the results of SCPT and RCPT investigations at the experimental Stegny site in Warsaw. The aim of the paper is to present the approach to determination of shear wave velocity and porosity of clayey soils. According to the test results obtained, it can be concluded that both applied techniques are very useful to estimate the distribution of clay deposits and some of their geotechnical parameters.

Small strain stiffness in overconsolidated Pliocene clays. A huge development of technical infrastructure, including the construction of many high-rise buildings, roads, railroads and extension of subway lines, took place over the recent years in Poland. Therefore, numerous planned investment projects require geotechnical data documenting the variation of soil parameters found in the subsoil. The shear wave velocity is one of the most important input parameters to represent the stiffness of the soil deposits. This paper focuses on the methods and devices using measurements of the shear wave velocity to estimate the initial shear modulus in cohesive soil. It is preferable to measure VS by in situ wave propagation tests, however it is often economically not feasible in all regions of Poland. Hence, a reliable correlation between shear wave velocity and parameters measured in triaxial cell or static penetration parameters would be a considerable advantage. This study shows results obtained from the bender elements tests and field techniques - seismic cone penetration test and seismic flat dilatometer, performed on overconsolidated cohesive soils in Warsaw. On the basis of the test results possible correlations between shear wave velocity (initial shear modulus), mean effective stress and void ratio are considered and four original empirical relationships are proposed. Moreover, the proposed formulas by two different techniques using triaxial apparatus and also RCPT cone were examined. The proposed formulas show a reasonable agreement with direct shear wave velocity profiles for clays and might be incorporated into routine laboratory and field practice

Based on the results of dynamic probing (DP), time-domain reflectometry (TDR/MUX/MPTS), resistivity cone penetration tests (RCPT), Marchetti dilatometer tests (DMT), and seismic dilatometer tests (SDMT), it is possible to develop a relationship to calculate the relative density (Dr) and degree of saturation (Sr) of selected sandy soils. Compiled databases from documented research points for selected sandy soils were used to construct and develop direct correlations between the measured pressures p0 and p1 from DMT and shear wave velocity (Vs) from SDMT, along with pore water pressures (u0) and atmospheric pressure (Pa). The results allowed us to make a preliminary prediction when evaluating the parameters. Further, they allowed limiting the use of an additional device, especially in the case of multilayer heavy preconsolidated subsoils. Moreover, soil physical and mechanical characteristics (temperature, humidity, pressure, swelling, salinity) measured from TDR/MUX/MPTS (laboratory/field-operated meter for simultaneous measurements of soil moisture, matric potential, temperature, and salinity—bulk electrical conductivity) were assessed. The main achievement of this paper is the original proposal of using a new nomogram chart to determine the relative density and degree of saturation based on DMT and SDMT tests.