The paper presents results of numerical calculations of a diaphragm wall model executed in Poznań clay formation. Two selected FEM codes were applied, Plaxis and Abaqus. Geological description of Poznań clay formation in Poland as well as geotechnical conditions on construction site in Warsaw city area were presented. The constitutive models of clay implemented both in Plaxis and Abaqus were discussed. The parameters of the Poznań clay constitutive models were assumed based on authors’ experimental tests. The results of numerical analysis were compared taking into account the measured values of horizontal displacements.

Natural fibres have recently gained attention as an alternative sustainable material for civil engineering applications due to natural fibres’ exceptional performance, including high strength, and their environmental-friendliness and cost-effectiveness. However, there are disadvantages to using natural fibres in extreme environments. Therefore, this paper reviewed the effect of moisture content and temperature on the tensile strength of potential natural fibres for engineering purposes. Furthermore, this paper also critically reviewed the influence of alkaline treatment on natural fibres’ tensile strength. This is significant because alkaline treatment enhances surface friction and the fraction of the revealed cellulose on the fibres’ surface, resulting in better mechanical interlocking. In conclusion, natural fibres demonstrate their potential for geotechnical applications due to the materials’ strong tensile properties after being subjected to treatment processes.

The historical past of a building has a key influence on the variability of geotechnical conditions. These conditions change with a modification of the structural system, a change in function or only architectural elements (fashionable in a given period). In the article, various geotechnical and geophysical surveys are described, which led to a discovery of potential causes of a structural failure at historical Castle of Dukes of Pomerania in Szczecin. The investigation resulted in a discovery of an underground tunnel system constructed under the Castle, which existence was only suspected. The tunnels were constructed primarily during II World War, but also before that period. The article summarizes facts discovered due to investigation as well as historical and geological background related to the execution of the reinforced concrete and masonry tunnels. The lesson learned resulting from this discovery is that great care should be taken when historical areas are considered, even if the structure seems to be massive and robust.

The paper presents the case study of geotechnical investigations reporting connected with expert’s opinion on undrained shear strength of organic sediments in the river valley at the north of Poland according to reinforcement methodology of c.a. 0,7 km highway embankment. Diversification of primary results caused additional research which revealed and confirmed liquid consistency of organic soils – several meters of organic and calcareous sediments – gyttja under the thin cover of peat. The main goal of the paper is a discussion on standardization of consistency of organic soils itself and additionally to point out very rare possibility of liquid consistency, finally not pointed in International Standards ISO 14688. The application of Atterberg limits in organic sediments is moot but even organic soil with water content higher than liquid limit can’t be classified and interpreted as very soft with description as soil which exudes between the fingers when squeezed in the hand. Such identification is practically impossible when it’s hard to squeeze because of gravitationally leaking through the fingers.

In civil engineering, underground structures are exposed to various georisks and require greater attention and awareness of the need to identify them at the earliest possible stage of investment preparation and implementation. The assessment of the interaction of objects in the underground space is a task that requires the analysis of many influencing factors resulting from the geometry and characteristics of the constructed structure and existing buildings, in the context of soil and water conditions. The correctness of such an assessment and forecast of the range and scope of these impacts requires knowledge of both construction and geotechnical issues, as well as knowledge of using the experience gained, including the analysis of the results of observations and monitoring measurements. One of the main challenges associated with underground constructions is their impact on existing buildings and other structures adjacent to the developed site. As these structures are often highly susceptible to excavation-induced ground movements, their behavior have to be considered in a design as one of the geotechnical-related limit states. As in the analysis of limit states, various computational models can be used to assess the impact of investments, including analytical, semi-empirical or numerical models. In the process of assessing the impact of underground structures, it is also important to identify additional elements of potential georisks, e.g. the impact of accompanying works, which in certain situations may have a significant impact on the construction process, requiring preventive measures. On a few examples from the construction of deep excavations and tunnels in different soil and water conditions, the article discusses the aspects of the role of the accuracy of the identification of soil and water conditions and the creation of a reliable and useful subsoil model as elements allowing for the identification and minimization of georisks and its proper management.

Plastic rocks can creep, therefore the knowledge of the rheological properties of the drilled formations is an important element of the drilling process and when choosing borehole designs. These properties of plastic formations also influence the way in which appropriate drilling technology and drilling mud properties are selected. The article presents the effect of basic rheological parameters of salt from the Fore-Sudetic Monocline deposit on the drilling of boreholes in the mining area of KGHM Polska Miedź, which in the future can be used as a good drilling practice to improve the safety and efficiency of drilling.

The process of drilling in plastic rocks may be hindered. Salt is a plastic rock and in the analyzed rock mass it is deposited at a considerable depth. The caprock exerts big loads on it, beside the temperature in the deposit intensifies the rheological properties of the rock. The creep process causes that the borehole contracts, therefore the knowledge about the rheological properties of the drilled rock is very important for establishing the safe time in which the well may remain uncased. The paper is devoted to the influence of basic rheological parameters of salt bed in the Fore-Sudetic Monocline on the process of drilling of a borehole in the area of KGHM Polska Miedź as these data can be used in drilling practice in the future.

This paper presents an experimental study on the leaching of heavy metals, toxic chemicals and persistent organic pollutants (POPs) – PAH, PCB and HCB – from soil dredged from the coastal area of Västernorrland in northern Sweden. The soil was stabilized with cement/slag. Samples were subjected to modified surface leaching and shake tests using technical standards of the Swedish Geotechnical Institute (SGI). The experiments were performed using different blends of binding agents (30/70, 50/50, 70/30) and binder quantities (120 and 150 kg/m3) to analyze their effects on leaching. Soil properties, tools, and workflow are described. Binders included Portland cement and ground granulated blast furnace slag (GGBFS). Samples were tested to evaluate the min/max contents of pollutants (μg/l) for heavy metals (As, Ba, Pb, Cd, Co, Cu, Cr, Hg, Mn, Mo, Ni, S, V, Zn) and the hydrocarbon fraction index in the excess water. The leaching of heavy metals and POPs was assessed in sediments after the addition of the binder. The comparison was made against the two mixes (cement/slag in 30/70% and high/low binder with low/high water ratio). The results showed that 70% slag decreases the leaching of heavy metals and POPs. The equilibrium concentrations of DOC and heavy metals at L/S 10 (μg/l) were measured during the shake experiments to compare their levels in the groundwater that was used as a leachate. The leached content was assessed at L/S 10 in the upscaling experiments using four samples for PAH, PCB and various fractions of hydrocarbons: C10–C40, C10–C12, C12–C16 and C35–C40. The shake test showed a decrease in the leaching of heavy metals and POP substances from the soil subjected to stabilization by a higher amount of slag added as a binder. A binder blend with 30% cement and 70% of GGBFS showed the best performance.

This study was carried out to evaluate the effect of steel slag (SS) as a by-product as an additive on the geotechnical properties of expansive soil. A series of laboratory tests were conducted on natural and stabilized soils. Steel slag (SS) was added at a rate of 0, 5, 10, 15, 20, and 25% to the soil. The conducted tests are consistency limits, specific gravity, grain size analysis, modified Proctor compaction, free swell, unconfined compression strength, and California Bearing Ratio. The Atterberg limit test result shows that the liquid limit decreases from 90.8 to 65.2%, the plastic limit decreases from 60.3 to 42.5%, and the plasticity index decreases from 30.5 to 22.7% as the steel slag of 25% was added to expansive soil. With 25% steel slag content, specific gravity increases from 2.67 to 3.05. The free swell value decreased from 104.6 to 58.2%. From the Standard Proctor compaction test, maximum dry density increases from 1.504 to 1.69 g/cm3 and optimum moisture content decreases from 19.77 to 12.01 %. Unconfined compressive strength tests reveal that the addition of steel slag of 25% to expansive soil increases the unconfined compressive strength of the soil from 94.3 to 260.6 kPa. The California Bearing Ratio test also shows that the addition of steel slag by 25% increases the California Bearing ratio value from 3.64 to 6.82%. Hence, steel slag was found to be successfully improving the geotechnical properties of expansive soil.

The demands placed on industry today are increasingly challenging and demanding. To meet these challenges, designers, contractors, and technology managers are constantly looking for effective solutions. Industry has always thrived on new technologies and innovations to achieve better results, so it is critical to undertake new developmental research to simulate and test new technological proposals. In this paper, the author describes a new direction in civil engineering technology that interdisciplinary couples solutions known to the bridge industry with geotechnical aspects in the technology space and the possibility of implementation in the construction industry. The author proposes the application of prestressing together with technological aspects of this solution to diaphragm walls, which are not only a temporary housing but also the foundations of a new investment. Thanks to this solution it is possible, among other things, to resign from one level of diaphragm expansion of diaphragm walls, which translates into cost optimization. It is an innovative approach to designing and most of all constructing the load-bearing structure, which directly influences the technological optimization of selected issues of completing the underground parts of the investment. Additionally, the presented solution contributes to the balanced execution of the investment by reducing the use of materials and construction equipment. The author discusses technological, execution and implementation problems related to the application of innovative solutions in construction companies together with examples of cost optimization. The author presents the results of conducted research with application of the proposed solution in the implementation of the underground commercial investment.

The road tunnel in Laliki was excavated in highly heterogeneous, severely tectonically damaged and mainly very weak rocks of the Western Carpathians flysch. In particular, the conditions were characterized by a high percentage of very weak laminated shale and weathered rock mass, an unfavorable and very steep slope of the rock layers and unstable hydrological conditions with outflows of water in loosened tectonic zones. That structure and properties of the rock mass highly uncertain. This paper describes the influence of geological engineering and geotechnical conditions on the primary lining of a main road tunnel. The deformation of the primary lining was analyzed in terms of the percentage share of sandstones and shale, geomechanical classifications RMR (Bieniawski 1989) and QTS (Tesar 1979), types of the primary lining and the use of rock bolts and micropiles. The analysis was preceded by characterization of geological engineering conditions and technological characterization of applied primary linings. Displacements of the primary lining, greater than acceptable, occurred several times in a top heading during tunneling. The primary lining was reinforced by additional rock bolts and wire mesh, a thicker layer of shotcrete and micropiles if deformation reached the emergency state for some types of linings and they didn't indicate any tendency for stabilization. The reinforcement was used until the deformation stabilization was achieved. In the most difficult conditions, the lining was reinforced by a longer micropile umbrella. Parameters for the primary lining were selected on the basis of ongoing geological engineering and geotechnical measurements, in accordance with NATM's principles. The rock mass around the tunnel in Laliki is an example of weak carrying capacity. The observed displacements in the rock mass indicate that the disturbed zone around the tunnel was heavily developed. The primary lining used in such conditions must bear a relatively high load capacity from overlying loosened material and therefore the lack of interaction with the surrounding rock mass should be assumed. The data obtained indicate that the use of the primary lining in the highly variable conditions in the Carpathian flysch requires accurate geological engineering and geotechnical analysis during the day-to-day process of tunneling in order to verify the projected assumptions. The primary linings should be reinforced as needed based on the results of geotechnical measurements, monitoring the interaction between the rock mass and the system of lining.

This article presents results of the numerical analysis of the interaction between heavy caterpillar tracks system and subsoil. The main goal of the article is to present an algorithm to design working platforms - temporary structures enabling the work of heavy construction equipment on weak subsoils. A semi-analytical method is based on the results of the numerical analysis performed with use of the finite element method (FE software ZSoil.PC [12]). The calculations were carried out for the piling rig machine - Bauer BH20H (BT60). Three ground models were adopted: Model 1: one layer - weak cohesive soil (clay); Model 2: two layers: weak cohesive soil (clay) and cohesionless working platform (medium sand); Model 3: one layer: strong cohesionless subsoil (medium sand). The following problems were solved: I) entry of the machine on the ground with various geotechnical parameters under each caterpillar tracks II) detection of the maximum permissible angle of ground slope.

The dynamic replacement columns are formed by driving a coarse-grained material into a soft soil by means of repeatable drops of a pounder. The final shapes of the columns are non-cylindrical and depend on the subsoil conditions. This paper presents results of the laboratory study on influence of the thickness of the soft soil on the displacements of the backfill aggregate during the driving process. A test box with one acrylic-glass wall was prepared, in which, over a load-bearing sand layer, a soft soil of various thicknesses (���� = 0.3, 0.4 or 0.5 m) was modelled using a semi-transparent acrylic polymer. The displacements of the backfill gravel particles were tracked by means of a high-speed camera. The material was driven by dropping a 0.2 m high (����) pounder. The results revealed that the distance between the bottom of the first crater and the top of the sand layer played an important role in directing the particles. At ����/���� = 2.5 pear-shaped floating columns were formed as the grains in the side zones were less affected by the pounder drops and their paths deviated from the vertical axis by not more than 50°. In case of ����/���� = 2.0 and 1.5, the column bases reached the bearing layer and the impact energy caused much larger vertical and horizontal displacements of the backfill material in the side zones – the observed largest angles were equal to 64° and even 90°, respectively. Eventually, the final column shapes resembled a non-symmetrical barrel and a truncated cone.

The paper presents a new geotechnical solution indicating a possibility of effective building structures protection. The presented solutions enable minimization of negative effects of underground mining operations. Results of numerical modelling have been presented for an example of design of preventive ditches reducing the influence of mining operations on the ground surface. To minimize the mining damage or to reduce its reach it is reasonable to look for technical solutions, which would enable effective protection of building structures. So far authors concentrated primarily on the development of building structure protection methods to minimize the damage caused by the underground mining. The application of geotechnical methods, which could protect building structures against the mining damage, was not considered so far in scientific papers. It should be noticed that relatively few publications are directly related to those issues and there are no practical examples of effective geotechnical protection. This paper presents a geotechnical solution indicating a possibility of effective protection of building structures. The presented solutions enable minimization of negative effects of underground mining operations. Results of numerical modelling have been presented for an example of design of preventive ditches reducing the influence of mining operations on the ground surface. The calculations were carried out in the Abaqus software, based on the finite element method.

In this paper, the authors present an extension of the scope of the previously conducted research to the full three-dimensional computer simulation (using the finite element method), which takes into account the interaction between: heavy caterpillar tracks system – working platform – weak subsoil. The article presents a computer model considering two caterpillars, resting on elastic-plastic sub-soil, with standard Mohr-Coulomb yield conditions, allowing for computer simulation of the behavior of the system up to achievement of ultimate limit state. The results of the above model are treated as the reference for a simplified Analytical Models of estimating the limit state, which might be used in design procedures. In turn, these Analytical Models are enhancements of previously presented one. The most important results concluding form the Analytical Model are simple interaction formulas, in the space of moments acting on the machine-subsoil system, limiting a domain of safety in given soil conditions.