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Evaluation of bearing capacity of CFA piles with bases widened by means of jet grouting

Rafalski Leszek, Szymankiewicz Czesław, Słowikowski Daniel, Petyniak Dariusz

Roads and Bridges - Drogi i Mosty

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2021

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Vol. 20, no. 3

253--265

EN

The paper presents the results of tests of continuous flight auger (CFA) piles with bases widened by means of jet grouting. During construction of bridge structures of the S8 expressway at the Salomea interchange in Warsaw, an experimental CFA pile with a widened jet grouted base was constructed and its ultimate bearing capacity was 1.5 times greater than the bearing capacity of the reference pile, and its allowable load was 1.65 times greater than the allowable load of the reference pile. It was observed that the full base resistance of this pile was mobilized at displacements corresponding to approximately 0.1 of the diameter of the pile. During construction of bridge structures of the S8 expressway on the bypass of Marki, load tests were performed on 17 CFA piles with widened jet grouted bases. It was determined that the average design value of bearing capacity of the piles was 1.23 greater than the average design value of loading specified in the design documentation and the average ultimate bearing capacity was 1.78 greater than the average design load. The average ratio of design bearing capacity determined from the load test equaled 1.23 and the average ratio of the ultimate bearing capacity equaled 1.89. Based on the experimental trials, the principles for calculation of bearing capacity of CFA piles with widened jet grouted bases were formulated.

PL

W artykule przedstawiono wyniki badań pali wierconych z podstawą poszerzoną metodą iniekcji strumieniowej. Na budowie obiektów mostowych drogi S8 na węźle Salomea w Warszawie wykonano doświadczalny pal i ustalono, że jego nośność była 1,5 razy większa od nośności pala bez poszerzonej podstawy, a obciążenie dopuszczalne tego pala było 1,65 razy większe od obciążenia dopuszczalnego pala bez poszerzonej podstawy. Stwierdzono, że całkowite opory podstawy tego pala zostają zmobilizowane przy przemieszczeniach odpowiadających w przybliżeniu 0,1 średnicy pala. Podczas budowy obiektów mostowych drogi S8 na odcinku obwodnicy Marek przeprowadzono próbne obciążenia 17 pali CFA z podstawą poszerzoną metodą iniekcji strumieniowej. Stwierdzono, że średnia wartość nośności obliczeniowej pali była 1,23 razy większa od projektowanego średniego obciążenia obliczeniowego, natomiast średnia nośność graniczna była 1,78 razy większa od projektowanego średniego obciążenia obliczeniowego. Średni wskaźnik nośności obliczeniowej wyznaczony na podstawie badania wynosił 1,23, a średni wskaźnik nośności granicznej wyniósł 1,89. Na podstawie badań doświadczalnych zdefiniowano zasady obliczania nośności pali CFA z podstawą poszerzoną metodą iniekcji strumieniowej.

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Preliminary field tests and long-term monitoring as a method of design risk mitigation: a case study of Gdańsk Deepwater Container Terminal

Miśkiewicz M., Mitrosz O., Brzozowski T.

Polish Maritime Research

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2017

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nr 3

106--114

EN

Appropriate risk assessment plays a fundamental role in the design. . The authors propose a possible method of design risk mitigation, which follows recommendations included in Eurocode 7. The so-called “Observational Method” (OM) can produce savings in costs and programmes on engineering projects without compromising safety. The case study presented is a complex design solution that deals with the heavy foundations of a gantry crane beam as one of the elements of a Deepwater Container Terminal extension. The paper presents a detailed process of the design of the rear crane beam being a part of the brand new berth, together with its static analysis, as well as the long-term results of observations, which have revealed the real performance of the marine structure. The case presented is based on excessive preliminary field tests and technical monitoring of the structure, and is an example of a successful OM implementation and design risk mitigation.

3

Pile model tests using strain gauge technology

Krasiński A., Kusio T.

Studia Geotechnica et Mechanica

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2015

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Vol. 37, nr 3

49--52

EN

Ordinary pile bearing capacity tests are usually carried out to determine the relationship between load and displacement of pile head. The measurement system required in such tests consists of force transducer and three or four displacement gauges. The whole system is installed at the pile head above the ground level. This approach, however, does not give us complete information about the pile–soil interaction. We can only determine the total bearing capacity of the pile, without the knowledge of its distribution into the shaft and base resistances. Much more information can be obtained by carrying out a test of instrumented pile equipped with a system for measuring the distribution of axial force along its core. In the case of pile model tests the use of such measurement is difficult due to small scale of the model. To find a suitable solution for axial force measurement, which could be applied to small scale model piles, we had to take into account the following requirements: – a linear and stable relationship between measured and physical values, – the force measurement accuracy of about 0.1 kN, – the range of measured forces up to 30 kN, – resistance of measuring gauges against aggressive counteraction of concrete mortar and against moisture, – insensitivity to pile bending, – economical factor. These requirements can be fulfilled by strain gauge sensors if an appropriate methodology is used for test preparation (Hoffmann [1]). In this paper, we focus on some aspects of the application of strain gauge sensors for model pile tests. The efficiency of the method is proved on the examples of static load tests carried out on SDP model piles acting as single piles and in a group.

4

Sposób zabezpieczenia zabytkowego muru oporowego

Sękowski J., Piotrowicz B.

Roczniki Inżynierii Budowlanej

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2015

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z. 15

85--95

EN

The paper presents a concept of protection of a historical retaining wall located at the top of Castle Hill slope by means of a load-reducing pile wall. The detailed description of the proposal has been preceded by a short overview of the Castle Hill history, its stability problems and applied solutions. A secant pile wall has been chosen as the method of protection for the historical retaining wall. It consisted of CFA piles 60 cm in diameter and of variable (7.3-10m) length. The pile depth has been estimated with the use of computer program GEO5 Sheeting Design, in which the method of modulus of subsoil reaction is used. To determine the magnitudes of stiffness coefficients for elastic support the iteration method by Schmitt has been chosen.

5

Comparative model tests of SDP and CFA pile groups in non-cohesive soil

Krasiński A., Kusio T.

Studia Geotechnica et Mechanica

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2014

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Vol. 36, nr 4

7--11

EN

The research topic relates to the subject of deep foundations supported on continuous flight auger (CFA) piles and screw displacement piles (SDP). The authors have decided to conduct model tests of foundations supported on the group of piles mentioned above and also the tests of the same piles working as a single. The tests are ongoing in Geotechnical Laboratory of Gdańsk University of Technology. The description of test procedure, interpretation and analysis of the preliminary testing series results are presented in the paper.