Eurocode 7 presents the problem of pile foundation design in a very general way. Only the main principles and requirements are specified. Such a concept is justified, however it is an impediment to practical engineering applications. Designers are obliged to independently search for suitable and reliable calculation methods, which are often scattered in numerous literature sources. This concerns to static calculation methods, piles bearing capacity determination and the settlement prediction for a single pile or a group of piles. The paper discusses these issues and presents some suggestions of methods and computational approaches using the current results of studies and long-term national experiences.

The necessity of optimising the foundation design encourages the use of methods based on in situ test results in the design of pile foundations. For this purpose, a cone penetration test (CPT) is commonly used. Design methods developed over the last few decades may differ not only in factors used for correlating the cone resistance with bearing capacity of a given type of pile foundation, but also in adoption of the representative cone resistance value for the calculations. Contrary to the design of pile foundation in relatively homogeneous ground conditions, in the case of heterogeneous stratification, the influence of the quality of test itself and the adoption of the average cone resistance for the calculation may have significant impact on the result. This is especially important issue when weaker strata, which may affect the end-bearing capacity, is present just below the pile, in its area of influence. The article presents some of the methods of averaging the measured cone resistance, how they may affect the obtained results and other factors affecting mainly end-bearing capacity of a single compressed pile.

The paper presents the issues concerning the testing of constrained moduli of subsoil based on static and dynamic penetrations, and use of these modulia to determine settlement of a building structure. The subject of analysis is an existing digester (WKF) – a cylindrical reinforced concrete building structure with conical domes. This fermenting tank is partially recessed into the ground, foundation depth is 1.8 m at the outer edges (with concrete primer), and 3.4 m in the middle. Generally, soil and water conditions in the area of analysis (i.e. around WKF) can be described as simple. The predicted final values of settlement of the WKF tank fell in the range of 110 ÷ 180 mm, exceeding significantly the final value announced by the designer of this tank. In order to determine validity of the designer’s decision to assume such parameters of subsoil under the tank, a series of subsoil tests were performed, including static (CPTU) and dynamic (DPL) penetration and dilatometer tests (DMT) dilatometer tests (DMT).

The paper presents the issue concerning the examination of the load index CBR ground for questionable land. In accordance with applicable regulations in the case of soft soil should always be done CBR study, regardless of the water – groundwater. In the current engineering practice, despite the Regulation on the technical conditions for highways, laboratory tests CBR native land are rarely performed. Markings index CBR made for different levels of the stress of the primary structural layers and land with different fractions of silt. The obtained results were correlated with the burden of the weight of structural layers of pavement in accordance with the new catalog of flexible pavements and semi-rigid. In addition, it shows the relationship between an indicator of the CBR and the content of silt fraction.

The subject of the paper are periodically layered composites. It is assumed that the components of the composites are homogeneous and isotropic. A model of heat conduction was constructed in which the classical Fourier equation with discontinuous and jumptype varying coefficients was substituted with an equation with constant coefficients. In the paper, stationary problems without heat sources were analysed. The numerical solution was obtained as a result of application of finite difference method. The influence of the number of periodicity cells on the accuracy of results obtained with finite difference method was investigated.

The main aim of the study was an attempt of determination of the stiffness modulus of sandy subsoil based on analysis of data recorded during the measurements of vibrations conducted at the surface of the ground. Field tests of acceleration of vibrations were carried out at measuring points located at a distance of 5 m and 10 m from the source of vibration. The Light Falling Weight Deflectometer was the source of the vibration, characterized by high repetition rate of pulse parameters. Measurements of vibration were executed using measuring system produced by Brüel & Kjær. The evaluation of the subsoil stiffness was made on the basis of obtained results in two ways. The first method was based on measuring the time of movement of the Reyleigh wave between the measuring points. The second method was to use the own author’s computational program. The program based on the finite difference method enabled the description of wave propagation in the ground under impact load.

The influence of the method of attachment of accelerometers to the ground on the recorded level of vibration accelerations is analyzed in the paper. Transducers were mounted to the ground in six different ways – using measuring bases in shape of a plate without any anchoring, anchored or not plate bases with an aluminum cylindrical heads, metal base rings with three pins, cross-bases with four pins and aluminum cylindrical heads and aluminum cylindrical heads buried at a certain depth in ground as well. In case of few measuring bases measurements were conducted using two types of accelerometers. The studies demonstrated that the method of attaching of accelerometers to the ground is crucial for the credibility of measurements. The best way of interconnecting transducers with the ground was shown in the paper. The resulting values of vibration acceleration may constitute a basis for a reliable analysis of the propagation of vibration in the subsoil, as well as support the development of methods of estimation of subsoil stiffness using surface seismic data.

A method of designing the foundation pad as a shallow replacement of organic soil is presented in the paper. The design examples present the influence of the pad width on bearing capacity and deformations of subgrade under strip foundations of a two-storey administration building, constructed on organic ground with thickness of 3 m. The pads with different width, determined by the value of the stress distribution angle β = 0°, 30° and 45°, were taken into consideration. It was stated that peat replacement is needed on the whole organic layer thickness, regardless of the width of the sand pad. The ultimate limit state fulfillment is possible only for the pad width over twice greater than the width of the foundation.

The article contains results of tests of geotechnical properties of fly ashes from the Skawina Power Plant. Samples of the ashes were taken from three discharge hoppers with electrostatic precipitators, marked as dedusting zones I, II and III. The research included determination of parameters characterising the particle size distribution, compactibility, capillarity, loss on ignition, water permeability and shear strength. The analysis of the results of the tests was carried out in the context of the use of the ashes in road building. It was found that the tested ashes from different dedusting zones have relatively small differences in physical characteristics and mechanical properties. The ashes do not meet the requirements for materials used in road building. It was pointed out that the improvement of the geotechnical properties of the fly ashes could be obtained by using mixtures thereof with other industrial wastes of coarser graining or by stabilisation with binding agents. Low values of permeability coefficient result in the classification of the tested ashes as suitable for sealing for example levees or landfills.

The study analyzed the impact of additional tower structure masses on the change of the frequency of its natural vibrations; it also made attempts to mathematical description of this impact. Considerations apply to the tower supporting the lighting system of the city stadium in Ostrowiec Świętokrzyski. The source of additional masses is the icing (frost, rime) and non-structural components constituting the technical equipment of the tower. The analysis was made by modeling by means of the Finite Element Method (FEM) of the structure with the assumption of a one parameter variation of its mass (i.e., the additional mass of all components, structural and non-structural, changes in proportion to one parameter, which is the outer surface of the element on which the ice layer is deposited). Solving the problem of natural vibrations, for subsequent models, representing different intensity of tower’s icing, the following natural frequencies have been established. Thus, the increase of the ice-layer thickness on the surfaces from 0 to 2.4 cm caused the reduction of basic natural frequencies by a value, consecutively: for f₁ → 26.9%; for f₂ → 27.2%. These values are important from the point of view of technical applications. The findings allow to formulate a postulate that, in the analysis of tower’s structure susceptibility to gusts of wind, structure’s mass variability resulting from its possible icing was taken into consideration.

Generally the verification of resistance to hydraulic failure, particularly to failure by hydraulic heave – ultimate limit state named HYD, is considered as the most difficult task for designers of many civil and hydraulic works. Moreover, this limit state is a kind of failure with very high hazard potential because of initiating failure by piping. The hydraulic heave typically occurs in the construction of deep excavation pits demands to lowering the groundwater level and in the construction of hydraulic structures (e.g. weirs) to storage of water in reservoirs. The verification of resistance within the HYD can be done according to the Eurocode 7 [PN-EN 1997-1:2008] using two different ways assuming the total pore pressure and the total vertical stress (eq. 2.9a) or the seepage force and submerged weight of soil prism (eq. 2.9b). In order to check the HYD state the seepage pressure, hydraulic gradients and flow forces should be determined. However, the way how to determine the seepage forces is not specified in PN-EN 1997-1:2008. This paper presents the results of verification against hydraulic heave for weir Jaktorów located in km 11+760 of Pisia Tuczna river. The characteristic values of the required actions have been determined using flow net by the use of numerical simulations with taken into account possible unfavorable conditions as variations in water levels above the soil prism and pore pressure in time as well as downstream excavation. The verification of HYD state shows an enormous influence of assumed condition and applied procedure on weir safety.

For the purposes of the construction of a new diversion weir on the Nysa Kłodzka River in Nysa, instead of geotechnical investigations required by Construction Law, only geological investigations were performed. The depth of subsoil recognition was too small and the number of boreholes, probing as well as the scope of the laboratory test did not meet the requirements of the third geotechnical category. Consequently, the layers arrangement and geotechnical parameters contained in the engineering – geological documentation were inconsistent with the reality. This caused incorrect design of the weir. In addition, according to the documentation, below the bottom of the wide foundation excavation, the cohesive soils in stiff state were located. In fact, there were suffosive fine and silty sands with a thickness more than 4.5 m with a few interbeddings of cohesive soil. Design based on the incorrect subsoil characteristics caused that sheet piling was ended in the sands only 2.5 m below the weir foundation level. While excavation, at a depth of 6 m, the piping took place. The rapid displacement of the lower end of the sheet piling has occurred, and excavation was filled with soil. It caused the total loosening of soil below foundation of the designed structure.

The main aim of the investigations was to analyze hydraulic flow conditions of a vacuum sewage system making a lot of problems during its exploitation and to propose corrective action which should be taken to eliminate these problems. The scope of the investigations encompassed a vacuum sewage system built in a village Starawieś nearby Warsaw. The paper presents the analysis of the obtained results of the investigations of negative pressure changes along the length of the vacuum collector pipeline with diameter of 225 mm, in conditions of technical exploitation of the vacuum sewage system. Negative pressure measuring devices were distributed in six determined points (ferroconcrete wells with ISEKI interface valves) along the length of the vacuum collector pipeline. The measuring devices measured pressure changes every minute, by 24 hours per day, for several days. Changes of the negative pressure in vacuum sewage systems depend on the frequency of opening of interface valves and on the negative pressure in a vacuum container. In order to let the interface valves open, the negative pressure in vacuum sewage pipelines cannot be lower than –20 kPa. The analysis of the obtained results of the investigations allowed to define the causes of malfunctioning of the vacuum sewage system. The main cause of the problems was that the passages of the vacuum collector pipeline under the national road No. 62 were built contrary to the design. After reconstruction of the aforementioned passages according to the design and after proper adjustment of opening times of the emptying valves, the tested vacuum sewage system operated properly.