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EN
The idea of strengthening the foundation using injection piles lies in transferring loads from the foundation to the piles Anchorage in existing structure and formed in the soil. Such a system has to be able to transfer loads from the foundation to the pile and from the pile onto the soil. Pile structure often reinforced with steel element has to also be able to transfer such a loading. According to the rules of continuum mechanics, the bearing capacity of such a system and a deformation of its individual elements can be determined by way of an analysis of the contact problem of three interfaces. Each of these surfaces is determined by different couples of materials. Those surfaces create: pile-foundation anchorage, bonding between reinforcement and material from which the pile is formed and pilesoil interface. What is essential is that on the contact surfaces the deformation of materials which adhere to each other can vary and depends on the mechanical properties and geometry of these surfaces. Engineering practice and experimental research point out that the failure in such structures occurs at interfaces. The paper is concentrating on presenting the experiments on interaction between cement grout and various types of steel reinforcement. The tests were conducted on the special low pressure injection piles widely used to strengthen foundations of already existing structures of historical buildings due to the technology of formation and injection pressure.
EN
The formation of a pile in the existing foundation and soil creates a new foundation construction which has a structure of foundation-pile-soil. This construction must be able to transfer loads from the foundation to the pile and from the pile to the soil. The pile structure has to transfer an imposed load. From the point of view of continuum mechanics determination of the capacity of such a system is preceded by the analysis of contact problem of three contact surfaces. Each of these surfaces is determined by different pairs of materials. The pair which creates a pile anchorage is a material from which the foundation is built (structure of stone and grout, brick and grout, concrete or reinforced concrete and grout. The pile structure is formed by grout and steel rebar. The pile formed in soil is created by a pair of grout and soil. What is important is that on contact surfaces the materials adhering to one another are subjected to different deformation types that are controlled by mechanical properties and geometry of these surfaces. In the paper, additional conditions that should be fulfilled for the foundation-pile-soil system to make load transfer from foundation to soil possible and safe are presented. The results of research done by the author on foundation-pile contact surface are discussed. The tests were targeted at verifying the bearing capacity of anchorage and deformation of piles made of grout and other materials from which foundations are built. The specimens were tested in tension and compression. The experiments were conducted on the amount specimens which is regarded as small sample to enable the statistical analysis of the results.
PL
Wyniki prezentowanych badań wskazują na to, że w wielu przypadkach wykonawczych nośność zakotwienia pala w fundamencie może w sposób istotny wpływać na bezpieczne rozwiązanie projektowe. Zasadna zatem wydaje się konieczność wprowadzenia dodatkowych warunków projektowych.
EN
The results of presented studies indicate that in many construction cases the pile anchoring capacity can significantly affect safe design solutions. Therefore, it makes sense to formulate additional design criteria. In the light of the studies, an important issue is to propose a design-friendly computational model of contact problem solving which accounts for any slippage function.
4
Content available remote Niskociśnieniowe pale iniekcyjne poddane osiowemu obciążeniu cyklicznemu
PL
Szerokie zastosowanie fundamentów palowych przy posadawianiu konstrukcji inżynierskich oraz przy wzmacnianiu już istniejących fundamentów o tradycyjnym posadowieniu bezpośrednim, zdeterminowało konieczność pracy pali w różnych warunkach ich obciążenia.
EN
In view of extensive use of pile foundations for engineering structures and reinforcement of existing traditional shallow foundations, the piles are expected to perform in various load conditions. Regardless of the loads with fixed time, structures (such as wind turbines, abutments of bridges, road and railway viaducts and structures in areas prone to seismic or para-seismic risks) are subjected to repeated loads with various nature of individual cycles.
5
Content available remote Zakotwienie wyciąganych z fundamentu niskociśnieniowych pali iniekcyjnych
PL
Istotą realizowanego poprzez pale posadowienia pośredniego jest możliwość przeniesienia obciążeń z budowli (fundamentu) do głębszych, „mocniejszych” warstw podłoża w układzie fundament – pal – grunt. Zdolność ta w takim układzie zdeterminowana jest zatem zespoleniem pala z fundamentem i z gruntem oraz jego spójnością wewnętrzną . Utrata zdolności do przenoszenia obciążeń w każdym z tych elementów powoduje, że pal staje się bezużyteczny.
EN
The concept underlying piles of intermediate foundation is the possibility to transfer the structure (foundation) load to deeper, “stronger” layers of subgrade by the foundation-pile-soil system. Such ability in the system depends therefore on joining the pile with foundation and soil and on its internal cohesion. The pile becomes useless on losing its capability of transferring load in any of those components.
EN
Low-pressure injection piles are widely used to reinforce the foundation of existing constructions from various historical periods. The crucial element is the proper interaction between the foundation and the pile that transfers the burden from the foundation to lower ground layers. Tests have been carried out on samples made of modern solid brick on lime-cement mortar. They have proven the usefulness of the self-anchoring connection between the brick foundation and a low-pressure injection pile. The connection is broken by disrupting the foundation and knocking the pile out of it. From a designing perspective, the important aspect is the load-bearing capacity of the foundation against imposed positive deformation on the plane perpendicular to the pile axis.
EN
The construction of proper anchoring is an essential precondition for an appropriate pile installation. Such anchorage must transfer at least the designed load capacity of the piles. Otherwise, the piles are useless. The presented research indicate the reasonableness of considering the anchorage bearing capacity on the design stage, as an important factor of their effective operation. This capacity should not be lower than the external bearing capacity of the pile, determined by the ground resistance.
PL
Istotnym warunkiem właściwej pracy pali jest skonstruowanie poprawnego ich zakotwienia w fundamencie. Zakotwienie to musi przenosić co najmniej obciążenie projektowe pali. Bez spełnienia tego warunku pale staja się bezużyteczne.
EN
Low-pressure injection piles are increasingly used both while reinforcing old foundations and designing new engineering solutions. In the course of design works, piles are often linked functionally with foundations. The research presented in this study does not confirm the guidelines according to which the coefficients reducing the bearing capacity of piles used as part of a set of piles should be applied. The area around a pile, which is affected by significant ground deformation, is very limited. According to the performed experiments, piles bear different in fluence on cohesive and non-cohesive soils. In both cases, a noticeable difference of pile and ground dislocation within their contact zone has occurred. It therefore seems necessary to verify the operating model of a pile in the ground, considering the slipping of both means in relation to each other.
PL
Próba doświadczalnej weryfikacji przemieszczeń niskociśnieniowych pali iniekcyjnych w warunkach podnoszącego pal obciążenia osiowego z ograniczoną deformacją powierzchni gruntu przez siły równoważące obciążenie wyciągające pal.
EN
In this text, it was attempted to experimentally verify the movement of low-pressure injection piles in the conditions of lifting axial forces and limited ground surface modelling by forces balancing the lifting pressure of the pile. The examination was performed in a duly prepared experimental area. As it has become evident during the comparison of survey results of piles extracted on a loose ground surface and in case of limited ground surface modelling, the proposed technology of test load consisting of a system of self-balancing forces may act in this respect as an authoritative test. It seems however that due to the great discrepancies between research results, it will be necessary to perform more tests as regards the maximum power value.
10
Content available remote Niskociśnieniowe pale iniekcyjne wyciągane z gruntu
PL
Niskociśnieniowe pale iniekcyjne znajdują szerokie zastosowanie w wielu konstrukcjach inżynierskich, w przypadkach gdy decydujące o stabilności konstrukcji jest jej zakotwienie w gruncie. Podczas projektowania istotne znaczenie ma poprawność modelu współpracy pala z otaczającym go gruntem w warunkach obciążenia, powodującego podnoszenie (wyciąganie) pala. W niniejszym tekście podjęto próbę doświadczalnej weryfikacji przemieszczeń niskociśnieniowych pali iniekcyjnych w warunkach podnoszącego pal obciążenia osiowego ze swobodną powierzchnią gruntu.
EN
Low-pressure injection piles are widely used in many engineering structures, where ground anchoring is of decisive importance. In the course of design it is important to ensure the correctness of the pile cooperation model with the surrounding ground in the situation of lifting pressure (pile pushing). In this text, it was attempted to experimentally verify the movement of low-pressure injection piles in the conditions of lifting axial forces and loose ground surface.
11
Content available remote Zespolenie iniektu z prętami SAS w palach iniekcyjnych
PL
Struktura pali iniekcyjnych zbudowana jest z zaczynu cementowego i zatopionego w nim elementu stalowego. W przenoszeniu obciążeń w konstrukcji naziemnej na grunt biorą udział oba elementy pala, dlatego tak istotnego znaczenia nabiera prawidłowość ich zespolenia.
EN
The injection pile structure consists of cement grout and steel-based element fused into it. Both pile elements are employed to transfer the load from overhead to ground structure. For this reason, joining those piles correctly is fundamental. According to some tests, joint failure leads to a disintegration of cement grout wrapping. In order to increase steel adhesion to cement grout in injection piles some SAS steel elements have been launched in the market. The tests confirmed the suitability of this type of rods to reinforce geotechnical elements, such as injection piles, ground anchors or studs.
12
Content available remote Przemieszczenia pali iniekcyjnych w warunkach obciążenia osiowego
EN
The results of relocation measurements carried out for injection piles under axial load in wide range of loads, considerably exceeding their normative carrying capacity, indicate that employed computational models do not represent actual deformation process in an appropriate way. Taking into account slide at the contact between pile side surface and soil makes it possible to approximate theoretical model behaviour to actual soil reaction. Moreover, the proposed model gives an opportunity to characterise many effects resulting from susceptible combination of two different materials - cement grout and soil. In particular when we abandon the assumption made in this work of the interaction between soil and pile deformation.
13
Content available remote Przemieszczenia gruntu obciążonego mikropalem iniekcyjnym
EN
The publication attempts to create a model of the pile performance in the soil, taking into consideration the processes occurring at the full load in its proximity. The soil exhibits the properties of a centre with variable inner structure, including variable porosity. The pile action on the soil concentrates in its closest proximity, at the sliding zone. Outside that area, the pile action on the soil disappears. In that area, the strength of the soil is considerably reduced. Experiments have not acknowledged the occurrence of effects resulting from the interactions between the piles. The displacement observed in the initial research has shown a number of properties which, to be confirmed, require further detailed experiments.
EN
The injection piles reinforced by structural sections are used in many protecting constructions. A character of these constructions causes that they work under conditions of complex loads. So it may appear state of stress of various signs in a pile section. A combination of structural section with cement grout surround is subjected in such a case to steel ironing from cement grout in ones fibers and in other ones forcing steel in to grout. A command of combination strength in both cases as well as of slip rate on the contact surface is essential by designing. The stress values accompanying the failure of combination which there were achieved during strength tests for stronger grounds have proven lower than normative capacity of pile side surface.
15
Content available remote Pale iniekcyjne zbrojone kształtownikami stalowymi
EN
When designing injection piles reinforced with various steel elements, special attention has to be paid to the effectiveness of the integration of the pile with the steel element. The integration parameters assumed for concrete complex constructions are not true for the cement grout and have to be determined empirically. Pilot lab studies have confirmed the limited applicability of both steel pipes and sections as reinforcement for the piles. The use of composite components for the construction of piles must be verified experimentally. It is necessary to carry out several studies, including some basic ones, that would allow to obtain mechanical parameters not only for the composition, but also for the cement grout as a construction material.
16
Content available remote Pale iniekcyjne w warunkach obciążenia osiowego : weryfikacja doświadczeń
EN
Injection piles, widely used in strengthening of existing foundations, have little experimental basis to verify their design assumptions. Relationships assumed on the basis of research on concrete piles are connected with substantial understatement in describing phenomena accompanying injection piles' loading. From a designing point of view, such understatement means designing with considerable margin. This paper attempts to enrich the experimental knowledge describing phenomena that accompany deep foundation works with the use of small-dimension pile elements, made of cement paste.
PL
Projektowanie głębokich wykopów, obejmujących swym oddziaływaniem znaczne obszary w zwartej zabudowie miejskiej powinno być poprzedzone analizą wpływu technologii jego wykonania na zabezpieczanie obiektów znajdujących się w bezpośredniej strefie oddziaływania. Metody analityczne przestają być wystarczające do prawidłowego rozpoznania tych zjawisk, zwłaszcza w skomplikowanych warunkach wodno-gruntowych oraz przy dużym stopniu geometrycznego skomplikowania projektowanej konstrukcji. W takich przypadkach najbardziej wiarygodna wydaje się być trójwymiarowa analiza numeryczna. Taką analizę przeprowadzono w programie ZSoil 12.12 dla kolejnych etapów wykonywania głębokiego wykopu zabezpieczonego ścianą szczelinową, zlokalizowanego w ścisłym centrum Krakowa. Prawidłowość obliczeń jest weryfikowana stałym monitoringiem geodezyjnym.
EN
Designing deep excavations in urban areas is a very complex geotechnical problem. Not only stability calculations should be conducted but also the influence on the objects behind the wall is to be checked to predict the settlements of the buildings around the excavation pit. Analytical methods are not efficient when analysing constructions in complicated ground conditions and very complex geometry. In such cases three-dimensional numerical analysis gives the most reliable results. Finite element method analysis in ZSoil 12.12 was conducted to analyze the construction steps of excavation pit supported by diaphragm walls. The construction site is located in the city centre of Cracow. Accuracy of the calculations is checked by appropriate geodetic measurements.
PL
W praktyce inżynierskiej, a w szczególności w starych strukturach zabytkowych, często występuje problem niedoboru nośności istniejących fundamentów. Szczególnie szerokie zastosowanie do zwiększenia nośności fundamentów znalazły pale iniekcyjne (mikropale).
EN
The technologies of indirect foundations frequently replace the traditional methods of dealing with the deficiency of load-carrying capacity, in the foundations carried out in the past. The use of injection piles (micropiles) has become particularly popular, so as to transfer loads from the structure to the stronger layers of soil. The use of the dynamic methods of testing piles, in terms of their quality, has become equally important. As of now, the low-stress SIT (Sonic Integrity Testing) percussion method is the subject of a particularly intense development. Its main advantages include simplicity and a short time of completion, making it possible to test virtually all completed piles. Another benefit is the possibility of testing the piles made in the past and anchored in foundations.
20
Content available remote Uwagi do projektowania w zakresie wzmacniania fundamentów palami iniekcyjnymi
EN
The problem of lack of carrying power of foundations made in the past is an inseparable part of renovation of great structures located in urban areas. Injected piles (micropiles) have found wide application in this scope. Despite the introduction of standardization and numerous scientific works dedicated to this subject, the method of design leaves much to be desired in many cases and has a decisive influence on the correctness of work executed later and its eff ectiveness. The analysis presented in the article indicates the necessary scope of identification and design of micropiles in accordance with Polish standards and the current state of knowledge in the field of construction theory.
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