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1

Numerical Modeling of the Degradation of the Normal Stress Under Large Number of Shearcycles

Bellayoune Assia, Messast Salah, Boulon Marc

Civil and Environmental Engineering Reports

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2021

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Vol. 31, no. 3

118--133

EN

The evaluation of friction is an important element in the verification of stability and the determination of the bearing capacity of piles. In the case of cyclic stress, the soil-pile interface has a relaxation which corresponds to a fall in the horizontal stress which represents the normal stress at the lateral surface of the pile. This paper presents an explicit formulation to express the degradation of the normal stress after a large number of shear cycles as a function of cyclic parameters. In this study we are interested in the exploitation of the cyclic shear tests carried out by Pra-ai with imposed normal rigidity (CNS) in order to demonstrate the phenomenon of falling of the normal stress. The approach presented in this paper consists in proposing a simple expression for estimating the degradation of normal stress as a function of cyclic shear parameters after a large number of cycles. The validation of this approach is verified by the application of this formulation to a real case where the comparison of the simulations made by this approach with those recorded on site shows the good adaptation of this approach to this type of problems.

2

Role of accuracy and quantity of field tests in engineering-geotechnical researches for construction

Kutliyarov Damir, Ryzhkov Igor, Kutliyarov Amir, Khafizov Ayrat, Zubairov Ruslan

Przegląd Naukowy Inżynieria i Kształtowanie Środowiska

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2020

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Vol. 29, No. 4

421--434

EN

The aim of this work is to summarize previously conducted studies on the optimization of the unequal geotechnical testing program and on the selection of the desired calculation indicator based on the results of such tests. The approximate, but quick and cheap tests (“express methods”) are recommended to be performed on a large scale and considered as a means of assessing the geotechnical structure of the site as a whole. It is proposed to carry out expensive “accurate” tests in a reduced volume and to use them as a means of correcting approximate tests. In the article, these issues are considered by the example of determining the bearing capacity of piles according to the data of static sounding (cone penetration testing – CPT), dynamic and static tests of full-scale piles. We propose the mathematical model for evaluating the informative content of the test complex, based on the concepts of information theory. The site is mentally divided into several sections, each of which is characterized by one of the possible values of the ultimate resistance of piles of a certain length. All variants of “placement in the plan” of possible values of pile resistances (“site images”) are considered. Initially, when nothing is known about the true value of the pile resistances in each section, all possible values of the pile resistances are assumed to be equally probable, i.e. the uncertainty of the situation is maximum. In the theory of information, such uncertainty is quantified by the value called entropy. When any test is performed at the site, the uncertainty decreases, and the more accurate the test the more significant is the decrease. The difference in entropy before and after the test represents the amount of information (in bits) that these tests carry. The calculations using this model showed that the information content of a large number of approximate tests can (due to heterogeneity of the soil) exceed the information content of small exact tests. Only one approximate test method can lead to the systematic error (overestimation or underestimation of the average value of the desired indicator). It is necessary to carry out control “exact” tests and approximate tests to eliminate such a danger. A technique is proposed for adjusting approximate estimates based on data from “accurate” tests, which ensures optimal “safety margins” in decisions being made.

3

Jak prawidłowo określać nośność poziomą pali w fundamentach mostowych?

Trojnar K.

Mosty

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2017

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nr 1

34--39

PL

W artykule przedstawiono różne metody obliczeń nośności bocznej pali fundamentowych z uwzględnieniem modelowania fizycznego i numerycznego, w układzie płaskim i przestrzennym. Analizy numeryczne i badania polowe fundamentów palowych wskazują, że poprawne uwzględnienie współpracy pala z podłożem gruntowym ma znaczący wpływ na ocenę jego sztywności bocznej i umożliwia przeniesienie przez pal większych obciążeń bocznych.

EN

Bridge supports, earth retaining structures and many other structures are typically subjected to significant horizontal forces coming from the soil pressure. In this case foundation on piles should comply with relevant requirements of the bearing capacity and the serviceability conditions for a designed bridge structure. The article presents different methods of the calculation of the bearing capacity of a pile foundation including the physical and numerical modeling in the one-dimensional and spatial systems. They indicate that a proper consideration of the soil-pile interaction has a significant impact on the assessment of the lateral rigidity of the latter and allows to transfer larger loads on it.

4

Analiza nośności pali FDP na podstawie wyników próbnych obciążeń statycznych

Sękowski J., Janosz Ł.

Roczniki Inżynierii Budowlanej

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2015

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z. 15

59--66

EN

Article presents characteristics of static load pile tests, as a proof tests. Results of three such tests are presented and analysed. The tests were conducted at FDP piles designed as a foundation for a building in unfavourable soil conditions. The results of static load pile tests were positive. Capacities of piles were 20-90% larger than the design capacities.

5

Projektowanie mostów wg Eurokodów - określanie nośności geotechnicznej pali wg PN-EN 1997-1

Sobala D., Siwowski T.

Mosty

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2015

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nr 2

64--69

PL

W artykule przedstawiono metody określania nośności geotechnicznej pali zgodne z zasadami PN-EN 1997-1 (Eurokod 7) oparte na wynikach badań statycznych nośności pali, wynikach badań podłoża oraz wynikach badań dynamicznych przy dużych odkształceniach lub wpędach/wzorach dynamicznych. Poszczególne metody określania nośności geotechnicznej przedstawiono w postaci procedur obliczeniowych.

6

Ocena nośności pali na podstawie badań sondą statyczną CPT

Konderla H.

Górnictwo i Geoinżynieria

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2011

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R. 35, z. 2

367-374

PL

W artykule przedstawiono możliwości oceny nośności pali na podstawie wyników badań sondą statyczną CPT. Omówiono metodę pośrednią wyznaczania nośności opartą na polskiej normie palowej. Opisano szczegółowo dwie metody bezpośrednie, które zostały wykorzystane w przykładzie liczbowym. Zamieszczono wyniki sondowania CPT wraz z interpretacją. W przykładzie liczbowym porównano wyniki obliczeń nośności fundamentu palowego za pomocą rozważanych metod.

EN

The possibilities evaluation of the bearing capacity of piles based on the static penetration test has been presentation in the paper. The indirect method of the bearing capacity calculate based on the Polish pile norm was discussed. Two direct methods were described in detail and used in the numerical example. One example of CPT result with their interpretation was included in the paper. The results calculation of the bearing capacity pile foundation were compared for considered methods.

7

Applying Artificial Neural Networks for analysis of geotechnical problems.

Sulewska M.

Computer Assisted Mechanics and Engineering Sciences

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2011

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Vol. 18, no. 4

231-241

EN

The paper presents a discussion of some applications of Arti?cial Neural Networks (ANNs) in geoengineering using the analysis of the following six geotechnical problems, related mainly to predictionand classification purposes: 1) prediction of Overconsolidation Ratio (OCR), 2) determination of potential soil liquefaction, 3) prediction of foundation settlement, 4) evaluation of piles bearing capacity, 5) prediction of compaction parameters for cohesive soils, 6) compaction control of embankments built of cohesionless soils. The problems presented are based on the applications of the Multi-Layered Perceptron (MLP) neural networks.

8

Dostovernost’ metodik opredelenia nesuscej sposobnosti zabivnych svaj

Pojta P., Svedovskij P., Dronevic A., Nevejkov A.

Budownictwo o Zoptymalizowanym Potencjale Energetycznym

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2009

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nr (6)

250--257

EN

In work some discrepancies of the normative documents on account of normative resistance ground in a plane of an edge driver piles and on their lateral surface are considered. The major factors influencing change physical - of the mechanical characteristics ground in a around piles space are revealed. The new technique of account of bearing ability of piles is offered.

9

Badania dynamiczne nośności pali

Gwizdała K., Brzozowski T.

Górnictwo i Geoinżynieria

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2008

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R. 32, z. 2

139-149

PL

Przedstawiono przykłady badań dynamicznych nośności pali wykonane w kraju. Metoda badań uznawana jest za porównywalną z badaniem statycznym, umożliwiając ocenę nośności pali. Podstawową zaletą metody dynamicznej badania nośności pali jest wyeliminowanie konieczności montażu urządzeń kotwiących oraz krótki czas potrzebny na przeprowadzenie badań. Szczególne zalety badań dynamicznych docenić można w przypadku, gdy warunki techniczne lub terenowe utrudniają przeprowadzenie próbnego obciążenia statycznego. Porównanie krzywych obciążenie-osiadanie uzyskanych na podstawie badań dynamicznych z krzywymi z próbnych obciążeń statycznych wykazuje generalnie dobrą zgodność wyników badań. Badania dynamiczne (DLT) należy kalibrować za pomocą próbnego obciążenia statycznego (SPLT), traktowanego jako badanie odniesienia dla danego obszaru posadowienia. Wykonanie większej liczby badań DLT pozwoli w przyszłości (zgodnie z Eurokodem 7) na określenie współczynników tłumienia dla warunków polskich oraz wprowadzenie odpowiednich współczynników bezpieczeństwa.

EN

Some examples of dynamic load tests (DLT) of bearing capacity of piles installed in Poland are presented. The testing method shown allows a good estimation of bearing capacity of piles and can be treated as equivalent to static tests. Basic advantage of dynamic method for the assessment of pile's bearing capacity is an elimination of anchoring equipment as well as relatively short time of test duration which becomes of particular importance in difficult site and technical conditions, especially for carrying out static pile load tests (SPLT). The comparison of load-settlement curves from dynamic tests with corresponding static load test curves reveals good agreement of the results obtained. Dynamic load tests should be calibrated by static load tests treated as reference tests for a given foundation area analysed. According to Eurocode 7, larger number of DLT tests will enable in the future a determination dumping coefficients for Polish conditions and introduction respective safety coefficients.