Pile Load Test Results as a Basis for Reliability Calculation with Parabolic Response Surface

The paper will discuss a method of analysing head displacements of piles subjected to lateral load test that is suitable for reliability calculation. The obtained results will be used for writing down the serviceability limit state equation related to a pile representing the group of piles under investigation. The obtained set of displacements for the test piles will be a base for creating a response surface function which may be used for determining reliability index of a pile foundation by means of FORM, SORM or Monte Carlo methods proposed by structural reliability theory. A classic response surface has a form of a polynomial of degree two. Unfortunately, this type of response surface produces erroneous reliability indices. The discussed method of allowable pile load estimation, based on load test results and using a parabolic response surface without an independent term for structural reliability theory calculations, is characterized by the easiness of obtaining a response surface. It is very easy to obtain results for this type of response surfaces by using FORM and SORM methods

Influence of varying soil properties on evaluation of pile reliability under lateral loads

A three dimensional probabilistic approach to analyzing laterally loaded piles is presented. Two typical subsurface models are used in the analyses: the first one consists of layered linear elastic soil where each layer has a random modulus of elasticity; while the second model takes the form of linear elastic soil with a random modulus of elasticity that increases with depth. Efficient step by step procedures for the reliability computation involving pile displacements are proposed. The solution is based on three-dimensional modeling by the finite element method. A series of results has been obtained for various values of elastic parameters of the soil. Next by a non-linear regression procedure a response surface is obtained. To get the final response surface allowing for a reliability analysis, an iterative algorithm based on the so-called design point concept is applied. The failure criterion is defined as the pile head displacement exceeding displacement threshold. The two cases of piles subjected to lateral load are computed. The paper illustrates the influence of the two distinct types of subsurface variability on the probabilistic analysis. A pronounced effect of the random variability of both the lateral force and the elastic modulus of the upper layer on reliability indices has been shown in results of numerical examples

Evaluation of Anthropogenic Substrate Variability Based on Non-Destructive Testing of Ground Anchors

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

Methodology of Dynamic Monitoring of Structures in the Vicinity of Hydrotechnical Works – Selected Case Studies

The constant development of geotechnical technologies imposes the necessity of monitoring techniques to provide a proper quality and the safe execution of geotechnical works. Several monitoring methods enable the preliminary design of work process and current control of hydrotechnical works (pile driving, sheet piling, ground improvement methods). Wave parameter measurements and/or continuous histogram recording of shocks and vibrations and its dynamic impact on engineering structures in the close vicinity of the building site enable the modification of the technology parameters, such as vibrator frequency or hammer drop height. Many examples of practical applications have already been published and provide a basis for the formulation of guidelines, for work on the following sites. In the current work the author’s experience gained during sheet piling works for the reconstruction of City Channel in Wrocław (Poland) was presented. The examples chosen describe ways of proceedings in the case of new and old residential buildings where the concrete or masonry walls were exposed to vibrations and in the case of the hydrotechnical structures (sluices, bridges)

Modification of vibratory driving technology for sustainable construction works

The Sustainable Development Goals were a remarkable advancement when adopted by the United Nations in 2015. For the first time, the world committed towards a wide spectrum of common goals ranging from climate action to sustainable cities from sustainable economic growth to inclusive industrialization. Sustainability is usually considered as “avoidance of the depletion of natural resources in order to maintain an ecological balance”. In case of civil engineering, it means minimization of environment-related costs of ongoing project, also in terms of temporary deterioration of life quality in vicinity of building site due to noise and mechanical vibrations. Such impacts may constitute environmental load within much longer time-frame than exposure time to negative influences itself. Numerous impacts of construction work on environment, sometimes not covered by any standards, from mechanical damages to facilities and infrastructure, those which are easiest to identify, through negative influence to comfort and health of local residents, to offset the balance of nature (e.g. by chasing out birds during breeding season) are observed. The paper provides exemplary actions which may be undertaken by construction work contractors to reduce adverse dynamic impacts – mechanical vibrations, with regard to geotechnical work related to execution of deep excavation shoring. Conclusions of the paper are of general nature and, independently of rules specified by standards, they can provide guidance on good practices

Modification of vibratory driving technology for sustainable construction works

The Sustainable Development Goals were a remarkable advancement when adopted by the United Nations in 2015. For the first time, the world committed towards a wide spectrum of common goals ranging from climate action to sustainable cities from sustainable economic growth to inclusive industrialization. Sustainability is usually considered as “avoidance of the depletion of natural resources in order to maintain an ecological balance”. In case of civil engineering, it means minimization of environment-related costs of ongoing project, also in terms of temporary deterioration of life quality in vicinity of building site due to noise and mechanical vibrations. Such impacts may constitute environmental load within much longer time-frame than exposure time to negative influences itself. Numerous impacts of construction work on environment, sometimes not covered by any standards, from mechanical damages to facilities and infrastructure, those which are easiest to identify, through negative influence to comfort and health of local residents, to offset the balance of nature (e.g. by chasing out birds during breeding season) are observed. The paper provides exemplary actions which may be undertaken by construction work contractors to reduce adverse dynamic impacts – mechanical vibrations, with regard to geotechnical work related to execution of deep excavation shoring. Conclusions of the paper are of general nature and, independently of rules specified by standards, they can provide guidance on good practices

Assessment of surface parameters of VDW foundation piles using geodetic measurement techniques

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

An Analysis of Excavation Support Safety Based on Experimental Studies

The article presents the results of inclinometric measurements and numerical analyses of soldier-pile wall displacements. The excavation under investigation was made in cohesive soils. The measurements were conducted at points located at the edge of the cantilever excavation support system. The displacements of the excavation support observed over the period of three years demonstrated the pattern of steady growth over the first two months, followed by a gradual levelling out to a final plateau. The numerical analyses were conducted based on 3D FEM models. The numerical analysis of the problem comprise calculations of the global structural safety factor depending on the displacement of the chosen points in the lagging and conducted by means of the φ/c reduction procedure. The adopted graphical method of safety estimation is very conservative in the sense that it recognizes stability loss quite early, when one could further load the medium or weaken it by further strength reduction. The values of the Msf factor are relatively high. This is caused by the fact that the structure was designed for excavation twice as deep. Nevertheless, the structure is treated as a temporary one

Application of Laser Scanning to Assess the Roughness of the Diaphragm Wall for the Estimation of Earth Pressure

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 Ka, Kp 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 Historical Earthworks of the Warsaw Citadel

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