Miocene Clays Research Articles

Effect of tree species and substrate properties on organic phosphorus forms in afforested Technosols

AbstractPlanted vegetation is considered one of the most important soil‐forming factors in the reclamation of degraded post‐mining lands for forestry. The objective of this study was to compare the effect of N‐fixing tree species and non‐N‐fixing tree species on the organic phosphorus (Porg) forms in technosols developing from various substrates. Samples were taken from the uppermost layer (depth 0–5 cm) of technosols afforested with black locust (Robinia pseudoacacia), black alder (Alnus glutinosa), silver birch (Betula pendula), and scots pine (Pinus sylvestris). Samples of the tree foliage and the O‐horizons were taken as well. The studied technosols developed from Quaternary sands (sands), fly ashes after lignite combustion (ashes), and Miocene clays (clays). The soil samples were measured for the contents of labile (POlab) and moderately labile organic phosphorus (POmod), phosphorus contained in fulvic and humic acids (Pfulv and Phum, respectively), and residual organic phosphorus (POres). The foliage and O‐horizon samples were measured for the concentrations of C, N, and P. The N‐fixing tree species had higher P concentration in their foliage than non‐N‐fixing tree species. However, in the O‐horizon, the highest P concentration was determined under birch and not under N‐fixers. The effect of tree species on the organic P (Porg) concentrations in the mineral soil was limited with significantly lower Porg concentrations under pine. The soil under this species contained less Pfulv, Phum, and POres. However, the percentages of POlab, POmod, Pfulv, Phum, and POres in soil Porg were nearly the same under all tree species. The largest effect on the Porg concentration and the contents of particular Porg fractions was from the substrate type. Sands contained much less Porg than the clays and ashes, but their percentage of POlab in Porg was much higher than in the two other substrates. We conclude that N‐fixing trees do not affect the concentration of labile organic P, and the major factor controlling this Porg fraction is the soil substrate quality.

Impact of Tree Species and Substrates on the Microbial and Physicochemical Properties of Reclaimed Mine Soil in the Novel Ecosystems

Evaluating how different tree species and substrates affect the microbial and physicochemical properties of technosols from combustion wastes and reclaimed mine soil (RMS) is vital in species selection to enhance restored ecosystem services. This research aimed to evaluate the impact of pioneer and N-fixing tree species and substrates on the post-mining soil microbial and physicochemical properties. Common birch (Betula pendula Roth) and Scots pine (Pinus sylvestris L.), as the commonly introduced species on reclaimed mine soils (RMS) in eastern and central Europe, were selected as pioneer species, whereas black alder (Alnus glutinosa (L) Gaernt.) and black locust (Robinia pseudoacacia L.) were selected as N-fixer species. Soil samples were collected from different RMS developed from three substrates (fly ashes, clay, and sand) and measured for the content of total nitrogen (Nt), organic carbon (Corg), exchangeable calcium (Ca2+), exchangeable potassium (K+), exchangeable magnesium (Mg2+), C to N ratio (C:N), basal respiration rate (RESP), and microbial biomass carbon (Cmic). The research indicated that tested tree species influenced water holding capacity (WHC), Nt, C:N, and RESP value. The highest Nt accumulation in soil was observed under N-fixing, but it did not transfer into higher organic carbon content under N-fixers. The soil under pine had a greater C:N ratio than the soil under birch, alder, and locust. The RESP rate was highest under birch. In terms of substrate type, RMS developed on Miocene clays exhibited higher carbon and macronutrient contents followed by ashes, whereas sands exhibited the lowest values of both physicochemical and microbial properties. The study suggested that both tree species and substrates affect microbial activities and physicochemical properties of RMS; however, the substrate effect is stronger.

Data-driven analytical mechanics of aging viscoelastic shotcrete tunnel shells

Based on the principle of virtual power, equilibrium conditions are established for the forces within a cross section of a tunnel top heading driven according the New Austrian Tunneling Method (NATM). External forces, namely impost actions and ground pressure distributions following a third-order polynomial, are analytically linked with internal forces, such as axial forces and bending moments, arising as integrals over the shell thickness, of circumferential normal stresses. The latter are related, via an aging viscoelastic shotcrete material model, to circumferential normal strains, as well as to radial and circumferential displacement components. This allows for analytical transformation of displacement measurement data collected at the crown and the footings of the shell segment, into ground pressure and impost action evolutions, together with all the associated force and stress quantities. For the Sieberg tunnel, driven in Miocene clay marl, our data-driven analytical mechanics model evidences virtually uniform ground pressure distributions, leading to a first rapidly increasing, and then mildly decreasing utilization degree of the shotcrete shell.

ДЕФОРМАЦІЙНІ ВЛАСТИВОСТІ МІОЦЕНОВИХ ГЛИН ОКОЛИЦЬ ЛЬВОВА (ЗА ПОКАЗНИКАМИ НАБРЯКАННЯ ТА ЗСІДАННЯ)

The results of experimental studies of the composition, physical properties and processes of swelling and shrinkage of Kosiv clays in the outskirts of Lviv are considered. The clays of the Kosiv suit occupy large areas in the Lviv city. They extend in the form of an almost continuous cover 3–5 km wide from the southeast of Zelena-street to the northwest of the village Riasna-Ruska. The total area occupied by clays exceeds 50 km2. The clay layer is covered by an almost continuous mantle with a thickness of 6– 10 m of degraded loess and other genetic types of sediments and is below the groundwater level, so their natural humidity does not change for a long time. The thickness of clays varies from 1–3 to 20–25 m. In some areas, in particular within the Lewandiwsky ledge of the Lviv plateau (Subotivska, Olesnytskoho, Syayvo streets, etc.), on the south-western outskirts of the plateau (Obroshyno village) and on the south-eastern slopes of Roztocze (Kleparivska street in Lviv, village of Vidnyky) they lie directly under the soil-vegetative layer or lowpower layer of man-made soil, in the aeration zone, directly are the subsoil of the foundations and have the ability to swell and shrink. Studies have shown that the mineralogical composition of the clay component contains 18.6 % montmorillonite, 35.1 % quartz, 17.5 % hydromica and 28.8 % feldspar. The particle size distribution of the soil is dominated by parts smaller than 0.01 mm. Clays have a firm consistency, low natural humidity and density. With additional moisture, they swell, and when moisture is lost, they shrink. The absolute value of the index of free-swell (sw) of the soil when it is moistened reaches 0.058, which gives reason to classify the soil as weakly swollen. The value of the swelling pressure is on average 0.48 MPa. The maximum linear shrinkage is 11 %, and volumetric – 18 %. The obtained data show that the Miocene clays (Kosiv suit) of the outskirts of Lviv are characterized by the ability to swell and shrink when their humidity changes and require detailed engineering and geological studies and a number of special measures to ensure the stability of buildings and constructions.

Undrained shear strength of Lisbon Miocene clay: a reappraisal based on triaxial and pressuremeter test results

Undrained shear strength plays a fundamental role on the behaviour of clays. In overconsolidated clays, this parameter is largely influenced by test conditions, namely consolidation stress. “Prazeres Clay” is a Miocene overconsolidated formation, that can be found in a significant part of Lisbon area. Over the last decades a number of very relevant constructions have generated a large database for physical and mechanical properties of Miocene clays. Included in a broader study at the Faculty of Engineering of Porto University about Miocene clay’s physical and mechanical properties, existing data was gathered, treated and critically analysed, in order to establish a useful framework for geotechnical designers. This paper presents the results obtained for undrained shear strength, obtained from triaxial tests and Ménard Pressuremeter tests. It addresses the main difficulties associated with test’s interpretation and presents a discussion on how theoretical values relate to experimental ones. The paper proposes a range of variation for Prazeres Clay’ undrained shear strength based on a significant amount of test results, that is considered to be useful for geotechnical design.Article HighlightsUndrained Shear strength is a relevant parameter for clays, and is usually derived from triaxial testsFor overconsolidated clays, this parameter is highly dependent on preconsolidation stress, and on its relation to in situ stress.Based on a significant set of data, the paper presents a simple methodology for estimating this parameter

Characterization of Moroccan steel slag waste: The potential green resource for ceramic production

Steel slag is one of the most common waste products from the steel making industry. In this research, building bricks based on electric arc furnace (EAF) slag were examined. Five mixtures were prepared by mixing variable percentages of EAF from 5 to and 25% by weight with Messinian and Miocene clays from NE Morocco. The effects of the slag content on ceramic proprieties were investigated during drying and firing over temperature ranging between 700 and 1100 °C. Shrinkage of fired clay bricks decreases with increasing the amount of steel slag. The water absorption and porosity of the bricks decreased with increased firing temperature due to a reduction of the connectivity of the pores. The decrease of porosity is linked to the formation of glassy phases confirmed by XRD results. The presence of EAF slag contributes to the formation of new crystalline phases such as gehlenite, cristobalite, lazurite, leucite and mullite. The addition of 15, 20 and up to 25 wt% of slug does not induce any significant variations in their technological properties.

Geological mineralogical and technological properties of Oligocene–Miocene clay deposits in altered volcanic rocks for the ceramic industry (Western Anatolia, Turkey)

Geological mineralogical and technological properties of Oligocene–Miocene clay deposits in altered volcanic rocks for the ceramic industry (Western Anatolia, Turkey)

Identification and Investigation of Subsidence Areas to Mitigate Karstic Risks in Urbanized Areas of Madrid, Spain: A Case Study

A multidisciplinary investigation was carried out in a karstic depression in a housing development under construction in Madrid to assess its stability. It was found that it is a small basin within a larger depression as a result of subsidence accumulated during the Quaternary. Subsidence has built up progressively in the Miocene clay cap and bedrock due to the underlying dissolution of gypsum rich intercalations. The preferential circulation of the dissolving subsurface flow is along a fault conditioned by subsidence, the formation of an elongated syncline along the fracture, and the alluvial basin. During the Pleistocene, a former lagoon zone was formed in this subsiding area; it was also a groundwater discharge zone. The decrease in recent times is very small and could be evaluated to be about 0.4 mm/year, and affects the alluvial zone and along the furrow of a fault zone, where the maximum average rate of subsidence would be 1.4 mm/year. This has led to the development of a relatively strong alluvium. It seems that under the alluvial deposits, a slow and diffuse dissolution is taking place of the shallower clayey gypsiferous levels, free of hypersoluble mineral species; this is somewhat more intense in the fault zone, which is more active hydrodynamically, where groundwater velocity is higher. Microgravimetry surveys indicate that only 5% of the area hidden under the alluvium shows anomalies, interpreted as residual soft clayey masses, or anomalous alluvial fillings of old dissolution voids. These pockets (“bolsones”), have dimensions of no more than 20 × 20 m and depths below 20 m. These measurements have been confirmed by boreholes and are the only points that would require special attention in the future construction of the urbanization. The urbanization work, in full development, is implementing solutions aimed at the stability of the road in the strips of alluvial studied.

Activity of phosphatases and microbial phosphorus under various tree species growing on reclaimed technosols

Tree species forming a symbiosis with N-fixing bacteria (N-fixing plants) may alleviate P deficiency in afforested technosols by increasing activities of phosphatases. The objective of this study was to compare the effect of rhizobial and actinorhizal N-fixing tree species and non-N-fixing species on the activity of phosphatases in various technosols. Soil samples were taken at two depths (0 – 5 cm and 5 – 20 cm) under black locust (Robinia pseudoaccaccia), black alder (Alnus glutinosa), silver birch (Betula pendula) and Scots pine (Pinus sylvestris) stands growing on technosols developing from Quaternary sands, fly ashes after lignite combustion as well as acidic and alkaline Miocene clays. The samples were measured for the contents of organic carbon (Corg), total nitrogen (Nt) and total phosphorus (Pt), texture and pH in H2O and KCl. Microbial analyses included determination of microbial biomass carbon (Cmic) and phosphorus (Pmic), basal respiration rate (RESP) as well as activities of acid and alkaline phosphatase and inorganic pyrophosphatase. Enzyme activities were expressed per soil dry (AcdPho, AlkPho, PyroPho for acid phosphatase, alkaline phosphatase and and inorganic pyrophosphatase, respectively) and per unit of Cmic as specific enzyme activities (AcdPhoSP, AlkPhoSP and PyroPhoSP for acid, alkaline and inorganic pyrophosphatase, respectively). The soils under black locust and alder exhibited higher AcdPho than the soils under non-N-fixing trees. The soils under black locust had also higher AcdPhoSP, AlkPhoSP and PyroPhoSP values and the soils under alder AcdPhoSP compared with the soils under pine and birch. The high Nt content was the major factor positively affecting absolute activities of phosphatases. However, high values of specific activities suggest a strong competition for soil P between N-fixing plants and soil microorganisms. In particular, the high P demand of black locust resulted in more intense microbial release of phosphatases and greater retention of P in microbial biomass. Our study indicated that both N-fixing tree species affected microbial release of enzymes involved in P cycling but the influence of rhizobial black locust was stronger than the influence of actinorhizal alder.

Evaluation of the Injana claystone from Central Iraq for the brick industry

This study aims to suggest an alternative to the use of quality agricultural soil in the brick industry (Iraq). The Late Miocene claystone bed in the Injana Formation in central Iraq was targeted through the study of 18 exposed sections that were sampled by using the trench sampling method. The claystones are characterized by quartz (36.4%) followed by calcite (32.8%), quartz (36.4%) feldspar (2.6%), gypsum (1.3%) and dolomite (0.7%), kaolinite (10.5%), illite (7.7%), chlorite (6.7%), palygorskite (6.0%) and montmorillonite (0.7%). New thermal mineral phases were formed at 950°C, including diopside (62.9%), quartz (18.4%), wollastonite (8.28%), akermanite (7.6%), Anorthite (6.25%), Nosean (4.9%), gehlenite (3.75%) and Lazurite (3.15%). The raw material's engineering tests showed that the Atterberg index for the plasticity varies from low to high, low volumetric and linear shrinkage during drying and firing with a temperature at 950°C. The raw material produced bricks with 155 kg/cm2 uniaxial compressive strength, 23.2% water absorption, and zero to low efflorescence. The results show the potential use of the Late Miocene clays of the Injana Formation to replace the existing agricultural grade muds presently being manufactured within the A and B category based on the Iraqi standard specification No.25 in 1993.

Assessing post-pliocene deformation in a context of slow tectonic deformation: insights from paleoseismology, remote sensing and shallow geophysics in Provence, France

The Provence region, located in the southeast of France, has experienced a few destructive earthquakes during the last centuries, such as the 1909 Lambesc earthquake or the 1509 and 1708 Manosque earthquakes. However, faults in the area experience slow slip rates (< 0.1 mm/yr) that preclude quantification of deformation using geodetic measurements. Active faults in Provence have long recurrence intervals, and the region experiences erosion under a Mediterranean climate where surface markers of such deformation are rapidly erased. As a consequence, several faults in the region may go unnoticed despite having the potential to generate earthquakes. This work focuses on the Vinon-sur-Verdon area in Provence, where a relatively narrow fault structure, the Maragrate fault, brings into contact Miocene clays and Pliocene conglomerates. Because of its proximity to a major nuclear research facility, this fault poses a potential earthquake hazard that justifies studies aimed at gaining insight into its mechanics and Quaternary seismic activity. In this context, a multidisciplinary approach has been implemented. A LiDAR campaign was undertaken to generate a 30-cm high-resolution Digital Elevation Model that depicts in detail the current fault morphology. In parallel, an electrical resistivity campaign was conducted and three trenches were opened. These investigations revealed a fault contact expressed by a fault gouge zone surmounted and sealed by numerous recent Quaternary periglacial and high-energy channel units. Radiocarbon and optically stimulated luminescence dating allowed the chronological reconstruction of sediment deposition and erosion cycles and of the most recent deformation event, older than 20 ka. These investigations did not allow us to demonstrate with certainty that these deformations are of a co-seismic nature. This work highlights the difficulty of identifying faults and studying the seismic hazard in intra-continental contexts.

Manufacture of Portland cement from Late Miocene claystone, Injana formation, Central Iraq

The aim of this research is to provide a potential reserve of claystone suitable for ordinary Portland cement (OPC) industry using clay from the geological formation instead of the recent clay currently being exploited with negatively affects the environment as they reduce the agricultural soil. For this purpose, the thick exposed bed of Late Miocene clays of Injana Formation was targeted and evaluated in terms of mineralogy and geochemistry. Many laboratory experiments resulted in the production of clinker which was also assessed and passed successfully for the OPC. The main raw materials required for cement production are limestone and clay. The over-consumption of the recent clay for OPC participated in the stimulation the use of Late Miocene claystones alternatively which are added to the raw mixture (RM) of cement at a certain ratio. The Late Miocene Injana claystones are composed of kaolinite, illite, and chlorite, quartz, calcite, feldspar, and gypsum. The raw material composed of claystones to limestones (1:3 volume) has provided a cement mixture of Silica Ratio (SR = 2.8), Alumina Ratio (AR = 1.94), Silica Saturation Factor (SSF = 0.9), Lime Saturation Factor (LSF = 90.2), and a clinker composes mainly of alite (51. 67), belite (26. 65), aluminate (9.65), and ferrite (8. 4). Among the most important conclusions of this study is the validity of the clay studied for the cement industry, and with this conclusion, this research has proven that there is a huge reserve that can be used for OPC and encourage to save the agricultural lands without extraction.

RESERVE ESTIMATION OF LATE MIOCENE INJANA CLAYSTONE BEDS FOR PORTLAND CEMENT AND BRICK INDUSTRY, MIDDLE OF IRAQ

The aim of this study is to evaluate the Late Miocene clay for manufacturing cement and bricks as an alternative to the recent clays from the agricultural land that are used typically for agricultural purposes. The claystone beds of the Injana Formation (middle of Iraq) was studied over 18 exposed sections, and sampled by using the trench sampling method. The industrial bed was determined as upper and lower beds. The upper industrial bed has different thicknesses varies from 1.0 m to 4.5 m, with an average of about 3.16 m and area of 576x106 m2.&nbsp; The lower claystone bed ranges from 2.0 m to 4.0 m with an average of about 2.7 m, and area 453614x103 m2. The clay reserve is characterized by a total area 1,029,614x103 m2, total volume 3,044,917,800 m3, bulk density 1.68 gm/cm3, and the average of compressive strength 154 (Kg/cm²). The total volume of overburden and inner burden is 1364676 x103 m3 with stripping ratio of the overburden 0.3. The estimation of the reserve of the claystone beds is 5,663,547,108 tons using the GIS method and 5,694,522,037 tons by triangles methods and classified as a C1 class based on the Russian system.

An archaeometric study of a Late Neolithic cup and coeval and Chalcolithic ceramic sherds found in the São Paulo Cave, Almada, Portugal

AbstractA detailed archaeometric study of a Late Neolithic cup found in the São Paulo Cave, Almada, Portugal, has been made, which, according to its unique decorative characteristics, may have had a ceremonial and symbolic utilization. Other 23 sherds, collected around the cup, dated early and late Chalcolithic periods, have also been studied. The conjugation of the information provided by the Raman, X‐ray diffraction, and X‐ray fluorescence emission experiments for the locally collected cup, sherds, and clays, with emphasis on the analysis of the ceramic bodies, allowed the characterization of the artefacts. In the reddish, brownish, or black parts of the surface of the cup, haematite, magnetite, and carbon black pigments were identified, whereas in the whitish parts, quartz was the most common mineral. Three main groups could be identified in the ceramic bodies, although all were made with the use of locally collected clays. In the first group, where the Neolithic cup is included, the potters used Miocene clays, most probably from the Palença clay sources, which were fired at a high temperature of about 950°C. The second group was also produced with raw materials of Miocene origin but the firing temperature was much lower, around 800°C, as revealed by the existing amount of muscovite. The third group, with clays of a Pliocene origin, exhibited a much lower content of calcium carbonate, as evaluated by the R index ([SiO2 + Al2O3 + K2O]/CaO), considered as ceramic raw material or a geological source indicator. These clays contain high amounts of kaolinite, muscovite, quartz, microcline, and anatase.

Soil carbon content and its stratification at the medium-term (5 and 8 years) in a semi-arid vineyard with cover crops

There is little information available on the evolution and stratification of soil C content (SCC) at the medium- to long-term in semiarid vineyards with cover crops. The objective was to determine SCC at different depths in the medium term (5 and 8 years) in a semiarid vineyard with different cover crops. The field experiment was conducted on Typic Haploxerept soil with a loam texture, pH 8.2, situated in a vineyard (cv. Tempranillo) located in the La Rioja region (northeast Spain) on Miocene sandstones, siltstones, clays and marlstones. Two different soil managements were evaluated: conventional tillage (CT) and continuous cover crop of resident vegetation (RV). Soil samples were collected from four soil layers (at depths of 0-2.5, 2.5-5, 5-15, and 15-25 cm) in June 2009 and June 2012, 5 and 8 years respectively after cover crop establishment. The SCC was determined and the SCC variation with respect to tillage treatment was determined considering the percentage of soil &amp;lt; 2 mm and soil bulk density. The results showed that the greatest increase in SCC occurred at 0-2.5 cm soil depth, increasing less with depth. The SCC annual increment in the whole soil sampled (0-25 cm) was 2.78 Mg C ha&lt;sup&gt;-1&lt;/sup&gt; year&lt;sup&gt;-1 &lt;/sup&gt;after 5 years and decreased to 1.98 Mg C ha&lt;sup&gt;-1&lt;/sup&gt; year&lt;sup&gt;-1&lt;/sup&gt; after 8 years of cover crop establishment. The lower SCC annual increase was not due to the maximum increase being reached in the whole of the sampled soil (0-25 cm). From 2009 to 2012, the SCC did not increase at the soil surface (0-2.5 cm), but did so in the subsurface zone (2.5-5 cm), although with an annual increment lower than that found at soil surface (0-2.5 cm). In conclusion, the steady state in SCC would not have been reached in the medium term (8 years) under cover crop, since there is still a increment of SCC in the subsurface layers.

Экологическая устойчивость почв лесных ландшафтов г.Иркутска и его окрестностей

The forest soils (burozems, sod podzolic soils, gray and gray metamorphic soils) and plant communities, altogether performing important environmental protection functions, were investigated in the vicinity of Irkutsk city in Russia (N52º17'24.03'', E 104º16’50.62"). The preservation of natural forest sites in the residential areas, as well as enhancing of the “green” infrastructure of the city by creating artificial forest stands with sustainable coenotic composition will significantly decrease contamination and pollution. The study assessed the potential of environmental susceptibility of soils in different districts of Irkutsk and its vicinity. The natural soil sustainability potential of the region results from the diversity of parent bedrock material, relief of the terrain, loamy and clay granulometry, derived from the Pleistocene loess-like loams and the Miocene clays, relatively high humus content of predominantly humate-fulvate composition, dense vegetation cover of pronounced biodiversity of trees (pine, aspen and birch), etc. Gray and gray metamorphic soils can be characterized as being environmentally the most sustainable. Taiga biocenoses were shown to contribute significantly to the improvement of the sanitary-hygienic and environmental status of the studied areas. The result underscores an urgent need to take into account soil and soil cover sustainability potential while creating a green environmental protection framework in the city and its vicinity. Sufficient fertility and environmental sustainability of soils in the studied area serve as a stable basis for the preservation of relic park forests and for the development of cultural and recreational landscapes in the region.

The diversity of ceramic raw materials used in the production of Neolithic vessels in the upper Vistula basin near Krakow

Specialist analysis of ceramics helps to identify the raw material used for their production and to determine whether the ma-terial was chosen deliberately for its specific parameters. The present study of Neolithic vessels and of sampled raw materials has shown that Linear Pottery population tended to use plastic Miocene clay, but silty alluvial loam was equally popular. A comparison between the types of vessels and ceramic bodies has proven that thin-walled vessels were more often made of material with a high content of grains of silty fraction, while thick-walled vessels were usually shaped from heavy clay. This suggests that there were certain rules to be observed when preparing the paste, despite the local diversity of raw materials.

Physical and Chemical Improvement of Clay Parameters Using Doped Marl with the Pozzolan in Fez Vicnity (Morocco)

Abstract Given the increasing exploitation of clay in Morocco for ceramic industry and for the purpose of the benefit reuse of this resource, a study is conducted in order to carry out the identification and characterization of Miocene clay after doping with pozzolan. The objective of this work is to improve the physicalchemical characteristics of Miocene clay of Fez region, by doping it pozzolan at different contents: 5, 10, 15 and 20%. Physical and chemical characterization of this clay was carried out before and after doping with pozzolan following various analytical technics, such as the X- ray fluorescence and geotechnical investigation. The result of geochemical analysis showed a higher rate of aluminum oxide (Al2O3), iron oxide (Fe2O3) and titanium oxide (TiO2). Further characterization of Atterberg limits have shown that the plasticity of doped materials increases. Similarly the mechanical behaviour of marls doped with pozzolan have significantly improved, providing a mechanical strength of obtained materials up to 670N when firing at 1000 °C, compared to the raw marls.

STATISTICAL-NUMERICAL ANALYSIS FOR PULLOUT TESTS OF GROUND ANCHORS

The paper presents an application of statistical and numerical methods for the determination of the forcedisplacement curves and that of pullout capacity of prestressed grouted ground anchors installed in Miocene clay. A regression analysis of data from a database of acceptance test records for ground anchors to create has been performed, the force-displacement curve of the tested anchor corresponding to the range of loads applied for acceptance tests has been created. A linear regression model, employing the weighted least squares method and robust standard errors techniques were concluded to serve as a reliable statistical method suitable for achieving this goal. The discovered linear regression dependence then served as a lower control limit for the displacement values calculated at the anchor head applying the numerical model. A finite element model has been created to predict the behaviour of ground anchors being installed in fine-grained soils. The developed numerical model that employs Mohr-Coulomb strength criterion constitutive model evaluates the influence of high-pressure grouting by development additional radial stresses and that of an increment of fixed length diameter.

Evaluation of Undrained Shear Strength of Miocene Clay from the Weight Sounding Test (WST)

Abstract Soil strength parameters needed for the calculation of bearing capacity and stability are increasingly determined from field testing. This paper presents a method to determine the undrained shear strength cuWST of the soil, based on the Weight Sounding Test (WST). The innovative solution which allows for a significant reduction of equipment needed for geotechnical field investigation is presented. The proposed method is based on an additional measurement of the torque during testing. It then becomes possible to estimate the undrained shear strength, cuWST of the soil, using the correlation given in this paper. The research results presented in this paper were carried out on selected cohesive soils, Miocene clays from the Carpathian Foredeep.