Basis of pile integrity testing with few case histories

U poslednjih nekoliko godina, ispitivanje integriteta ugrađenih šipova postalo je veoma popularno na gradilištima u našoj zemlji. Pri tom, posebno mesto zauzima zvučna metoda, 'Sonic Integrity Test' kao pouzdana, jeftina i vremenski malo zahtevna, a namenjena ispitivanju kvaliteta izvedenih šipova. U radu su prikazane osnove metode, teorijske postavke i nekoliko primera iz naše prakse.In recent years pile integrity testing have gained great popularity on sites all over the country. Special place among other methods belong to acoustic 'Sonic Integrity Test' method which is reliable, inexpensive and little time consuming. This paper presents discussion on basis, theoretical aspects and few case histories

Assessment of liquefaction hazard by in situ CPT test analysis and indexing indicator of soil

Procena seizmičkog ponašanja zasićenog tla u uslovima zemljotresa zasniva se na geotehničkim istraživanjima i ispitivanjima i poznavanju seizmičkog režima izučavanog područja. Likvefakcija se obično pripisuje rastresitim, sitnozrnim, jednoličnim peskovima bez sadržaja plastične frakcije. Međutim, novija iskustva ukazuju da i finozrna i grubozrna tla mogu pretrpeti značajne deformacije nastale kao posledica delovanja cikličnih napona indukovanih zemljotresom. U radu je analizirana podložnost tla na pojavu likvefakcije na primeru rezervoara (R-27) za skladištenje nafte u Smederevu.Assessment of seismic behavior of saturated soils during earthquake is based on geotechnical investigations and knowledge of the seismic regime of studied area. Liquefaction is usualy related to loose fine-grained, uniform sands free of plastic fractions. However, recent experience suggests that the fine grain and coars grain soils can undergo significant strains as a consequence of the cyclic stresses induced by earthquake. The paper presents analysis of liquefaction susceptibility of soil on example of the reservoir (R-27) in Smederevo

Geotehničko inženjerstvo instituta za ispitivanje materijala IMS

Razvojem građevinskog konstrukterstva, projektovanja i izgradnje objekata pod rukovodstvom vrhunskih stručnjaka Instituta IMS, u vreme postojanja Jugoslavije, razvijala se i svest o potrebi uvođenja geotehničkog inženjerstva u okviru instituta. S obzirom da su se, u fazi projektovanja, pojavlji-vali problemi na koje je trebalo dati odgovore po pitanju fundiranja objekata, to se vremenom javljala i potreba za uvođenjem geotehničkog inženjerstva kao posebnog centra u okviru Instituta IMS. U tom smislu, paralelno sa razvojem i implementacijom geotehničkog inženjerstva, stvarana su i nova iskustva u ovoj multidisciplinarnoj kompleksnoj oblasti koja povezuje građevinarstvo i geologiju. Hronološki posma-trano geotehničko inženjerstvo u Institutu IMS može se pode-liti na tri vremenska perioda: prošlost 1948-2000.god. kao period razvoja, implementacije i projektovanja građevin-skih i geotehničkih konstrukcija, sadašnjost 2000-2023. god, period uvođenja multidisciplinarnih savremenih metoda ispi-tivanja tla i geotehničkih konstrukcija uzimajući u obzir soft-versko-hardverski inženjering, i budućnost od 2023. god. kao period značajnije primene informatičkih tehnologija i siste-ma u rešavanju geotehničkih problema

Analysis of foundation settlement from progressive moistening of silty clay

Nisu retki primeri vidljivih oštećenja (pukotine i prsline po fasadnim zidovima) na starijim građevinama Beograda koje su fundirane plitko. Najčešće je to posledica neravnomernih sleganja koja često nastaju usled nepredviđenog provlažavanja tla ispod temelja. Ovo provlažavanje je uglavnom lokalnog karaktera i u takvim uslovima je neminovna pojava diferencijalnih sleganja. U ovom radu su izloženi rezultati istraživanja koji ukazuju da pored veličine zone uticaja promene vlažnosti u tlu u horizontalnom pravcu i proračunatih vrednosti sleganja, treba analizirati i ukupnu promenu zapremine tla ispod temelja.Examples of visible damage (cracks on the facade walls) on the shallow founded older buildings in Belgrade are not rare. Usually, this is a consequence of unequal settlement resulting from the unexpected moistening of soil under foundation. Moistening usually occurs locally and differential settlement is inevitable in such conditions. This paper presents the research results, which indicate that besides the size of impact zone of moisture change in the soil in horizontal direction and calculated settlement values, total change of soil volume under foundations should be analyzed

Determination of the Pile Stiffness Matrix Based on the Pile Load Test Results and the Effect of Pile Interaction

The paper presents the determination of the elements of the pile stiffness matrix based on pile load test results, made for the needs of modernization of oil refinery for NIS in Pancevo. The tests were carried out on CFA and Franki piles system. However, only the results for CFA piles are shown in this paper. Load tests included axial, tension and horizontal loading. Bearing in mind the geomechanical composition of the terrain and the results of penetration testing (CPT), it has been concluded that the soil resistance can be approximated as a linear function by depth. By approximating the soil by the Winkler model and using the results of the horizontal pile load test, the equivalent gradient of the modulus of soil reaction for the work load level is determined analytically, and then, the pile flexibility coefficients for horizontal load. For vertical load, the coefficient of flexibility is determined directly on the basis of the load-settlement curve. Based on the flexibility coefficient, a matrix of flexibility and a stiffness matrix are determined. The effect of the pile interaction for horizontal and vertical loads was introduced in an approximate way, through the reduction of coefficients of the stiffness matrix. The entire process of determining the stiffness matrix of the pile is illustrated by practical example of a pile group connected by an ideal rigid cap

The systematization of analytical and numerical methods of landslide stability calculation

Na osnovu analize mnogih naučnih radova, autori su dali prikaz sopstvene originalne sistematizacije analitičkih i numeričkih metoda proračuna stabilnosti klizišta, pri čemu mnoge od njih tek treba dodatno da se unaprede, implementiraju i testiraju na kompleksnim 3D modelima klizišta. Metode proračuna stabilnosti klizišta klasifikovane su u pet grupa: analitičke jednokoračne, analitičke višekoračne (iteracije kliznih površi), numeričke višekoračne (iteracije kliznih površi), numeričke inkrementalno-iterativne (nelinearne) analize i numeričke inkrementalno-iterativne (nelinearne) analize, uz primenu numeričke integracije u vremenskom domenu. Primenom sprovedene sistematizacije metoda proračuna stabilnosti klizišta, može se vrlo efikasno razmotriti koji je tip metode optimalan za analizu klizišta i koji tip metode je potrebno koristiti u fazi preliminarnih i finalnih analiza za naučna istraživanja i stručne projekte.According to the analysis of a large number of scientific papers, the authors of the paper presented their own original systematization of the analytical and numerical methods of landslide stability calculation, with a large part of them still to be further improved, implemented and tested on complex 3D landslide models. Methods for calculating the stability of the landslide are classified into five groups: analytical single-step, analytical multi-step (iterations of sliding surfaces), numerical multi-step (iterations of sliding surfaces), numerical incremental-iterative (nonlinear) analysis and numerical incremental-iterative (nonlinear) analysis, applying numerical integration in the time domain. By using the systematization method of calculating the stability of the landslide it can be very effective to consider which type of method is optimal for landslide analysis and which type of method should be considered in the phase of preliminary and final analysis for scientific research and expert projects

Pile integrity testing: Testing and results analysis

U radu su prikazani karakteristični primeri ispitivanja integriteta šipova sa analizom rezultata, pri čemu se metodologija ispitivanja oslanja na postojeće ASTM standarde, ali i na metodologiju ispitivanja prikazanu u naučnom radu "Ispitivanje integriteta i nosivosti šipova: metodologija i klasifikacija", koji je publikovan u ovom časopisu. Ispitivanja šipova sprovedena su primenom licenciranih oprema za test integriteta šipa sa senzorom (SIT) i test integriteta šipa sa sondama (CSL). Ispitivanjima su prikazane korektne i problematične situacije, koje se pojavljuju prilikom analize integriteta šipova. Ukazano je na aspekte primene talasne teorije, ali i na procesiranja signala i numeričke analize. Takođe, posebno je skrenuta pažnja na potrebu izrade plana ispitivanja integriteta šipova kod objekata s velikim brojem šipova.The paper presents typical examples of pile integrity testing and the results analysis, whereby the testing methodology relies on existing ASTM standards, as well as on the testing methodology presented in the scientific paper Pile Integrity and Load Testing: Methodology and Classification, published in this journal. The pile tests were conducted using licensed equipment for Sonic Integrity Test (SIT) and Crosshole Sonic Logging (CSL). The tests have shown the correct and problematic situations that arise when analyzing pile integrity. Some aspects of the wave theory implementation, but also of signal processing and numerical analysis have been indicated. Also, the need to develop a plan for testing the integrity of piles in structures with a large number of piles has been emphasized

Probabilistic analysis of bearing capacity of piles with variable parameters in cpt test and calculation according to the requirements

A probabilistic concept for determining pile bearing capacity is presented, taking into account the variability of CPT test parameters and methodology of calculation according to the requirements of Eurocode 7 (EN 1997-1: 2004). Based on a single initial (real) CPT test, a larger number of generated (simulation) CPT tests are introduced drawn from solutions of statistics and probability theory. Research has found that the best solutions are achieved using the DA 2 design approach for n(CPT) > 10 tests. Taking into account the deterministic and probabilistic approach in the analysis of pile bearing capacity, it is found that for the DA 2 design approach, the ratio of pile bearing capacity obtained from simulation and the capacity as determined through three methods (Mazurkiewicz, Van der Veen and hyperbolic approximation) is Rcd, /Pu = 1.148. Using the reliability index, the following values of partial resistance factors are obtained: λ, s /P 1.1, λ, b /P 1.1, which also points to the DA 2 design approach

Physical-Mechanical Properties of Cement Stabilized RAP/Crushed Stone Aggregate Mixtures

The paper presents and analyzes the results of testing the properties of cement stabilized mixtures of reclaimed asphalt pavement (RAP) and crushed stone aggregate (CSA). Tests were carried out on reclaimed asphalt pavement and crushed stone aggregate mixtures with varying RAP content (0%, 20%, 40%, 60% and 80%), as well as with a varying addition of cement (3%, 5% and 7%). The purpose of these tests was to determine the optimal proportion of recycled asphalt pavement in a mixture with crushed stone aggregate, and the optimal addition of cement as a hydraulic binder. Furthermore, the aim was to determine physical-mechanical parameters: the indirect tensile strength (Rt) and the dynamic modulus of elasticity (E), which are applied in pavement design during the process of cold recycling. On the basis of the obtained values, categorization of the stabilized mixture was carried out according to the standard EN 14227-10: 2006, which continues to be applied in the design of pavements. The maximum proportion of recycled asphalt in the stabilized mixture was determined as being up to 60%; the stabilized mixture was categorized into the "T1" and "T2" categories - gravelly soils

Investigation of the mortar and concrete resistance in aggressive solutions

U radu je prikazan utjecaj dva agresivna rastvora – sulfata i nitrata na žbuku i beton. U eksperimentalnom radu ispitivane su prizme od žbuke s 5 % specijalnog dodatka. Četiri vrste betona su također izložene agresivnim rastvorima. Kemijska otpornost ispitivana je prema metodi Koch-Steinegger. Kako je uvjet za otpornost kod agresivnih rastvora da zatezna čvrstoća žbuke nije niža od 70 % u odnosu na referentne prizme njegovane u vodi, može se zaključiti da žbuka i beton izrađeni s kombinacijom cementa i dodataka, prikazani u ovom istraživanju, nisu otporni na rastvor amonijak nitrata ali jesu na sulfatnu koroziju.Testing the influence of two aggressive solutions - sulphate and nitrate on mortar and concrete was presented in this paper. Experimental work included testing of mortar prisms with 5 % special admixture. Also, four types of concrete were exposed to aggressive solutions. The chemical resistance was tested according to the Koch-Steinegger method. As a condition for resistance in aggressive solution means that flexural strength of mortar prisms is no less than 70 % of referent prisms cured in water it can be concluded that mortar and concrete made with combination of cement and admixture presented in this investigation are not resistant to ammonium nitrate solution, but are resistant to sulphate corrosion