Marek Wyjadłowski

This paper presents the results of numerical investigations focused on a structural assembly consisting of thin-walled perforated steel beams joined to a particleboard panel. The simulations were performed using the finite element method (FEM), incorporating both physical and geometric nonlinearities, along with detailed modeling of contact interactions between the beams and panel elements. The primary objective was to establish load-capacity curves for the central beam in structural systems with spans ranging from 3 to 6 m, and to identify failure modes associated with different span lengths. To verify the reliability and accuracy of the numerical approach, laboratory tests were conducted on two representative configurations with spans of 3 and 6 m. Additionally, the mechanical properties of the beam materials were evaluated using samples extracted from the tested elements. The experimental findings confirmed the numerical model’s accuracy and its suitability for analyzing structural responses across the full span range considered.

This study presents a procedure applied to design problems for lateral loaded piles. Calculations for a rigid concrete pile in non-cohesive soil are conducted with the aim of estimating the allowable horizontal force using the methods of Broms and Petrasovit. Random sets are applied to represent the uncertainties of soil parameters, including the internal friction angle and unit weight. Random variables are described using log-normal and beta distributions. Random set theory is utilised to represent variability in the form of probability boxes, possibility distributions, cumulative distribution functions, or intervals. Based on the assumed distributions of the subsoil, the lower and upper bounds for the precise probability of fulfilment of the limit state function of a laterally loaded pile are estimated. The reliability calculation procedure is implemented using the R package (R Studio v2024.12.1+563), and the limit forces and reliability indicators calculated using the two considered methods are compared. The presented procedure serves as an example of the use of a probabilistic approach for the assessment of the capacity of a laterally loaded pile, using a setup for the task involving set-based data and discrete probability distributions.

This research investigates the influence of the scale effect on the bearing capacity of fine-grained subsoil under undrained conditions. The analyses were conducted based on laboratory tests of silty clay. Uniformly compacted samples were subjected to an unconfined compression test. The research was performed on cylindrical specimens. Three different variants of the diameter D (38 mm, 70 mm, 100 mm) and the corresponding height H = 2D were analyzed. Based on the tests results, the unconfined compression strength q_u was determined, and from this, the undrained shear strength c_u was calculated. The obtained results showed a clear decrease in c_u with increasing sample size. However, in the existing reference documents, there are no specific guidelines for calculations of bearing capacity with consideration of sample size effect on the soil shear strength. Therefore, this study utilized the laboratory soil test data to calculate the bearing capacity of undrained subsoil, taking into account the seismic impacts, with a particular focus on spread foundations.

The correct estimation of earth pressure is important for the design of earth retaining structures and depends, among others, on the surface morphology of retaining structures. The diaphragm wall created as a protection of a deep excavation located in an urbanized area was selected as a research object. Terrestrial Laser Scanning (TLS) was used for the investigation of the unique surface (in real-world dimension) obtained by tremieying the concrete in different soil layers. An original and innovative procedure for concrete surface description was developed, which includes steps from the TLS measurement to the determination of the roughness parameters. The tested samples from anthropogenic soil, medium sand, and sandy gravel, map the real diaphragm wall surface. The surface roughness parameters in different soil layers were compared with the reference surface obtained by cast against steel formwork. The following parameters: Sa, Sdr, and Vmc are indicated as being the most useful in numerical description of the concrete surface type and in allowing the determination of the soil surface friction. The novelty of this study is the estimation of the parameter δ (friction angle between the retaining wall surface and the soil), which is, among others, a function of the wall surface roughness. The influence of the type of surface on earth pressure are generally recognized in laboratory tests. Based on the estimated in situ values of δ, the more reliable active and passive pressure coefficients K_a, K_p were calculated for the tested soil layers. The conducted study has a practical significance for designing of retaining construction and makes progress in determination of surface roughness required in Eurocode 7.

The purpose of this paper is to describe the variability of soil rheological properties based on research carried out using load tests of ground anchors under complex geotechnical conditions. The heterogeneity of soil should always be considered when designing geotechnical constructions. In the present case, the earthwork created at the Warsaw Slope revealed an embankment of anthropogenic origin, located in a geologically and geomorphologically complex area of the Vistula valley slope. Excavation protection was anchored mainly in soils of anthropogenic origin. When the acceptance tests of the ground anchor were completed, the subsoil randomness was confirmed using nondirect, geostatistical methods. A standard solid rheological model with nonlinear fitting to the data was used. This model was established to describe the creeping activity of the ground anchor more accurately. The characteristics of man-made embankments were described using the parameters obtained with the rheological model of the subsoil.

Diaphragm walls are deep extended walls through granular or cohesive soils in shallow water table areas. This paper focus problems involved in excavating diaphragm walls including dynamic impact on the environment. Construction of diaphragm wall involves extracting a soil trench while simultaneously keeping heavy viscous slurry (bentonite) filling the excavation to provide lateral pressure that must be at least equal or greater than lateral soil pressure. Extraction of soil with machinery causes vibrations to be transmitted to the adjacent buildings. The research presented in the paper is also to assess the effectiveness of the concrete diaphragm wall in damping vibrations transmitted to the surrounding buildings. The first execution phase of the technology when a vertical finite-length trench element is excavated under a hydrostatic support from inside of a bentonite slurry is under consideration.

In this study, we analyzed the methods and technologies used for constructing earthworks and military engineering in the latter period before the industrial revolution in Poland. The research object, the Warsaw Citadel, is a source of knowledge about military heritage from the aspect of conservation and protection of specific engineering achievements, which were dictated by early Russian geopolitical doctrine. Within the framework of the ongoing project of material heritage protection and popularization of history, the fortress has been transformed into a modern museum building. The new symbolic message of architecture was redefined, leaving behind the gloomy dominance elements in the scenery of the nearby city. In this study, reception tests of ground anchors were used for analysis. They were treated as a tool to determine the heterogeneity of fortification of historical earthworks. In the presented calculation procedure, limitations in the availability of geotechnical tests were overcome. Geological terrain layout and embankment excavation technology significantly impacted their quality and reliability. Currently, the embankments are slashed with anchored retaining walls. Ground anchors were used at short distances and were tested according to the national standard procedures. The results of the load tests are based on the physical properties of the subsoil, the conditions of contact with the supporting elements of the anchors, and the material properties. The soil interaction with the anchors is described using a rheological model, the constants of which were obtained using a fractional derivative model. The spatial variability of the rheological model parameters is presented using theoretical semivariograms matching the empirical data. The semivariograms explain the spatial correlation of the tested constants of the rheological model of the substrate with the anchors. The results of non-destructive testing were influenced by factors such as time and consolidation processes. The obtained results allowed us to directly draw conclusions about the repetitiveness of embankment features and indirectly about the quality of their construction.

The importance of surface roughness and its non-destructive examination has often been emphasised in structural rehabilitation. The presented innovative procedure enables the estimation of concrete-to-concrete strength based on a combination of low-cost, area-limited tests and geostatistical methods. The new method removes the shortcomings of the existing one, i.e., it is neither qualitative nor subjective. The interface strength factors, cohesion and friction, can be estimated accurately based on the collected data on a surface texture. The data acquisition needed to create digital models of the concrete surface can be performed by terrestrial close-range photogrammetry or other methods. In the presented procedure, limitations to the availability of concrete surfaces are overcome by the generation of subsequential Gaussian random fields (via height profiles) based on the semivariograms fitted to the digital surface models. In this way, the randomness of the surface texture is reproduced. The selected roughness parameters, such as mean valley depth and, most importantly, the geostatistical semivariogram parameter sill, were transformed into contact bond strength parameters based on the available strength tests. The proposed procedure estimates the interface bond strength based on the geostatistical methods applied to the numerical surface model and can be used in practical and theoretical applications.

This article presents in situ research on the side surface of Vor der Wand (VDW) foundation piles using 3D laser scanning and close-range photogrammetry to assess the morphology of pile concrete surface. Contemporary analytical methods for estimation of the bearing capacity of the foundation pile surface require determination of the parameters of the concrete roughness and the model of the surface being formed, which corresponds to the pile technology used. Acquiring these data is difficult due to the formation of piles in the ground and their subsequent work as a structure buried in the ground. The VDW pile technology is one of the widespread technologies of foundation pile used in practice. These piles exhibit a specific configuration of the lateral surface, which is related to the simultaneous use of auger drilling and casing that rotates in opposite directions. Two geodetic techniques most often used to measure the geometry of buildings are terrestrial laser scanning and close-range photogrammetry. To empirically verify the suitability of these two techniques for describing the VDW pile surface parameters, a two-stage field study was performed. In the first stage, the measurements of concrete test surfaces were conducted. This surface was formed in a smooth formwork and its roughness parameters (in accordance with ISO 25178-2: 2012) were calculated and compared with the reference surface. In the second stage, measurements of the secant VDW sheet pile wall protecting the deep excavation were carried out. The roughness parameters of the pile surface were calculated for the selected areas in diverse geotechnical conditions. The original procedure for processing data (obtained using the above techniques) for assessment of roughness parameters of unique concrete surfaces was presented. The conducted research demonstrates that a pulse scanner has very limited usefulness for determination of roughness parameters for very smooth concrete surface; however, the photogrammetry techniques give acceptable results. In regard to the VDW pile surface, the results obtained from both measurement techniques give satisfactory consistency of the roughness parameters. The relative errors of calculated roughness parameters do not exceed 29% (average 12%). The proposed procedure may improve the accuracy of the assumed friction factor between pile surface and soil for assessment of the pile shaft bearing capacity for various pile technologies and soil conditions.