The paper presents the results of geological investigations of ice-dammed clays from Wierzbica near Serock (Central Poland). Physical and mechanical properties of varved clays were determined mainly during in situ tests. Different available equipment and methods were used for determining current geological and engineering conditions. Static tests CPT(U), dilatometer tests (DMT) and pressure meter tests (PBP) were performed and compared. Deformation modulus E, shear strength cu, yield pressure σy, limit pressure pl, and other parameters were evaluated. The selected methods were compared with respect to differences between the obtained results. With the use of statistical methods, the variability of ice-dammed lake sediments is presented. For this reason, the parameters should be carefully estimated. The geological environment is still diverse and difficult to apprehend. Histograms of collected data illustrate distribution of mechanical properties of varved clays from Wierzbica.
Results of a series of CRL-type consolidation tests on alluvial deposits form Vistula Delta "Żuławy ”, conducted with diverse load rates are shown. Such approach revealed diversified strain response of tested material. Dividing loading into stages has made increasing of stiffness, which may be applicable on the practice field.
Vistulian Glaciation ice-dammed lake clays with a varved texture were investigated. The study was focused on numerical determination of horizontal permeability depending on the depth and clay content. Direct assessment of these parameters is a rather complex and time-consuming issue. Therefore, a shortened methodology is offered based on the obtained relationships and the analysis of the dissipation process of excess pore pressure. The studies included mainly in situ tests: Marchetti dilatometer test (DMT) and BAT piezometer test. These methods allowed obtaining the values of the coefficient ofpermeability kh and changeability ofpore pressure u0 in a vertical profile. Investigations included 17 permeability tests using a BAT piezometer and 6 measurements of the coefficient of permeability kh, based on dissipation DMT tests. Results of in situ tests were compared with laboratory test results of the clay content. Values of the horizontal coefficient ofpermeability kh were correlated with the clay content f of varved clays. This relationship shows a high coefficient of correlation. A new formula was also proposed for the prediction of the coefficient of permeability kh in varved clays based on the pore pressure u0 stabilization curve, and thus shortening significantly the process of the coefficient kh determination.
The results of the possibility of geophysical methods application (such as geoelectrical ones, including ground penetrating radar and electrical resistivity tomography) to identify areas of loose sands were presented in the article. Registered anomalies obtained from geophysical survey have been verified by geological and engineering tests (drillings and dynamic probing). Measurements were carried out along the part of the lateral earth dam, consisting of man-made soils with a thickness of approximately 7 m and underlying alluvial medium grained sands. The results obtained from the geophysical survey and direct assessment of density by means of dynamic probing allowed to demonstrate the relationship between a specific type of geophysical anomalies and the density of non-cohesive man-made soils.
An analysis of cation-exchange capacity (CEC) variability of peats is presented in vertical profiles from eastern and central Poland. CEC values were compared with ash content (Ac), pH and CaCO3 content. Eight peatlands were selected for research in the following areas: Warsaw Plateau (2 objects), Siedlce Plateau (2 objects), Lubartów Plateau (2 objects), Nałęczów Tableland (1 object) and Dobrohusk Depression (1 object). The peatlands represented a fen peat type of similar botanic compositions of sediments, but they differed in the area, peat thickness and drainage conditions. Characteristic regularities in CEC variability were noted in the peatlands and there were three types of CEC variability in vertical profiles. Carbonate peats (types 1 and 2) had the highest pH and definitely the highest values of CEC. In vertical profiles, there was also a zonation, but the regularities similar to non-carbonate peats were not observed. Different distribution of physical and chemical parameters were established in vertical profiles in partly drained peatlands (with a muck layer on top) with non-carbonate peats (type 3) and there were three distinct zones in vertical profiles, with different Ac and CEC. Determination of the vertical CEC variability and other physical and chemical parameters in peatlands made it possible to distinguish zones with potentially most beneficial isolation conditions.
The paper presents the data on an Eemian–Late Glacial sedimentary sequence from the Zwierzyniec site, central Poland. A number of boreholes document one or two organic layers that occur beneath one or two horizons of clayey and silty deposits of ice-dammed lakes. This study demonstrates to which extent the Zwierzyniec site can contribute to a better understanding of the palaeoenvironmental changes during the Eemian–Vistulian time-frame in central Poland. To study it, a multi-proxy approach was applied, involving: palynological and plant macrofossil analysis, study of rounding of quartz grains and morphology of their surface, and investigations of sand mineralogy and till petrography. The results show that a till bed is overlain by a sandy series corresponding to the glacial-interglacial transition. Either one or two distinct peaks of organic accumulation are evidenced by peat horizons. The lower horizon records spectra with hazel and hornbeam, and did, therefore, accumulate in the Eemian. Observed only in some boreholes, the upper peat horizon marks the Brørup (or the lower part of the Rederstall stadial) represented by forest-steppe conditions with patchy mosaics of larch and further transition into sedges and herbaceous taxa. Localized in between the two peat sequences, the sandy horizon marks a long-lasting aeolian transformation with weathering by frost in the Early Vistulian. Again, significant changes of the palaeoenvironmental regime occurred, and are manifested in the one or two horizons of the glaciolacustrine sediments. This corresponded to the last glaciation in the region, when the ice-dammed lakes formed during the Main Stadial.
The selected parameters of the Wartanian and Odranian tills, with relation to their spatial occurrence, grain size distribution, mineralogical composition, matric suction and other physical characteristics, are presented. The assessment of the lithogenesis and stress history on the microstructure is attempted. The comparison of the compression and permeability characteristics from field and laboratory tests has been performed. Laboratory consolidation tests carried out with up to 20MPa vertical stress, revealed two yield stress values, one in the range of a couple hundreds kPa, the other in the range of a couple thousands kPa. Based on those results, the reliability of the soil preconsolidation assessment, with the use of the two different methods is discussed. The aspect of the triaxial strength reduction under the dynamic loading of diverse frequency and amplitude is raised. The research results depict a variety of possible geological-engineering characteristics, under the divergent constraints scenarios, of compression or strength weakening origin. The effects of the specialized research program will widen the possibilities of physio-mechanical and structural characterization of soils for geological-engineering purposes.
This paper presents the test results of horizontal hydraulic conductivity (k) of fen peats from eastern Poland. Three fen peatlands in the Lubartów Plateau (3 objects marked as LP1, LP2 and LP3) and two in the Siedlce Plateau (2 objects marked as SP1 and SP2) have been selected. Studied objects represent valley bogs type and are similar in peat thickness, but different in the occupied area. They are also vary in terms of botanic compositions and basic physical and chemical parameters of peats. The BAT permeameter was used to in-situ measurements of horizontal hydraulic conductivity. Horizontal hydraulic conductivity of studied peats varies from 1.3×10-8 m/s to 1.1×10-6 m/s. The lowest values of horizontal hydraulic conductivity were observed for silted (high-ash) carbonate peats and amorphous or pseudo-fibrous peats, while the highest values were observed for unsilted (low-ash) non-carbonate peats of fibrous structure. The analysis of variability of horizontal hydraulic conductivity showed that in each case the lowest values were observed for the bottom of the studied profile. The study allowed to indicate the specific areas within the peatlands differing in permeability and identify the role of individual objects as natural geological barriers.
Appropriate assessment of spatial variation of soil and hydrogeological conditions is a crucial issue in recognizing foundation soil. The best methods to achieve this goal are those that supply continuous rather than scattered data on soil medium variation. Electrical resistivity was measured with the resistivity cone penetration test (RCPT) and electrical resistance tomography (ERT) with electrodes spaced at 1 and 3 m in order to discriminate peat layers beneath low-resistivity clays. Soil conditions determined by drillings and ERT were not concordant, therefore resistivity modelling of the medium was conducted based on geological units determined by drillings and values of apparent resistivity obtained from RCPT. The strata thickness and electrode spacing is shown to have influence on resistivity imaging in complex soil conditions.
W artykule zaprezentowano wyniki sondowań sejsmicznych typu SCPT, przeprowadzonych w iłach warwowych okolic Radzymina. Badania wykonano za pomocą aparatury SCPTu firmy Geotech. Rezultaty pomiarów poddano analizie statystycznej w celu opracowania zależności korelacyjnej prędkości fali ścinającej Vs od oporu na stożku qt. Analizy odniesiono do obowiązujących w światowych badaniach związków korelacyjnych wiążących prędkość fali ścinającej z parametrami penetracji sondowań statycznych.
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This paper presents a method of seismic piezocone tests. It presents a brief description of the SCPTu Geotech testing apparatus and testing methodology. The results obtained at Mokre test site from in situ measurements of seismic wave velocity in varved clays are presented and analyzed. Local statistical correlations between shear wave velocity Vs and cone resistance q1 are presented in this paper.
Omówiono wyniki badań geologiczno-inżynierskich iłów zastoiskowych z rejonu Radzymina. Parametry mechaniczne otrzymano w toku badań wykonanych w warunkach in situ przy użyciu presjometru Menarda. Do testów zastosowano najnowszy model firmy Apageo wyposażony w elektroniczny system rejestracji GeoSPAD. Otrzymane dane zestawiono i porównano z wynikami z sondy statycznej CPT oraz dylatometru Marchettiego DTM. Przy zastosowaniu wspomnianej aparatury dokonano oceny modułu ściśliwości, naprężenia pełzania, naprężenia granicznego, współczynnika parcia gruntu w spoczynku i in. Zwrócono uwagę na rozbieżności w uzyskanych wartościach w zależności od metodyki badań. W artykule przedstawiono także sytuację geologiczną iłów zastoiskowych występujących w badanym rejonie.
EN
The paper presents the results of engineering-geological studies of ice-dammed clays from Radzymin area in Poland. The mechanical parameters were obtained from the in situ tests performed with Menard pressuremeter. Tests were carried out using up to date control-test unit GeoSPAD. The results were set and compared with those from static test (CPT) and dilatometer test (DMT). Pressuremeter modulus, creep pressure, limit pressure and coefficient of earth pressure at rest and others parameters were evaluated. The differences between the results obtained from selected method were noticed: Geological conditions of ice-dammed clays in study area were also presented in the paper.
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W niniejszym artykule autor zaprezentował wyniki badania współczynnika prekonsolidacji OCR iłów warwowych z okolic Sochaczewa i Radzymina. Ocen tych dokonano za pomocą nowoczesnej aparatury badawczej jaką jest dylatometr Marchettiego. Rezultaty poddano analizie w nawiązaniu do historii geologicznej iłów zastoiskowych pochodzących z okresu zlodowacenia Wisły. Pozwoliło to na nową ocenę zaskakująco wysokich wartości współczynnika prekonsolidacji rejestrowanych obecnie.
EN
In the paper the results of the study of overconsolidation ratio OCR of varved clays from Sochaczew and Radzymin area were presented. Tests were performed by using the up-to-date research apparatus i.e. Marchetti's dilatometer DMT. Results were analyzed with reference to geological history of varved clays formed during Vistula glaciation. They allow to explain the high values of overconsolidation ratio presently recorded. Interpretation of the preconsolidation studies of these soils require to take into consideration a effects of cementation, which aren't connected with additional loading i.e. overburden, iceland.
This paper presents the results of the field research using a new, prototypical geoelectrical equip-ment, that were developed for the soil resistance (Borowczyk &Porzeżyński, 2003). These studies were carried out in Plecewice near Sochaczew, where an open pit with varved clays is situated. Lithological changeability of varved clays was determined by the author through detailed laboratory testing. Then the results of research were compared with those derived from the new geoelectrical equipment tests and were related to varve thickness qualitative and quantitative evaluation of the soils in the vertical profile with the novel method was demonstrated. Further, the geological situation of the investigated area is presented in this paper.
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