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1

Calibration of an unsaturated air–water–soil model

Monnet J., Boutonnier L.

Archives of Civil and Mechanical Engineering

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2012

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Vol. 12, no. 4

493--499

EN

A theoretical model of unsaturated soil is presented. It takes into account the three main components of the soil: the air; the water; and the soil particles. It uses the principle of effective stress on four different domains: unsaturated with the air in continuous phase (Domain D1), unsaturated with the air occluded in contact with the particles of soil (Domain D2), unsaturated with air bubbles (Domain D3), and saturated with the air dissolved into the water (Domain D4). The model is validated on isotropic compression tests and on oedometer tests. The determination of the parameters of the unsaturated model is explained and the mean values of the parameters are presented.

2

Numerical analysis for an interpretation of the pressuremeter test in cohesive soil

Monnet J.

Studia Geotechnica et Mechanica

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2008

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Vol. 30, nr 1-2

41-49

EN

We present the theory used for the interpretation of the pressuremeter test in cohesive soil and its extension to the conventional limit pressure, which is defined as the pressure at the borehole wall for a volume increase ?V equal to the initial volume of the borehole. This conventional limit pressure can be directly measured with the pressuremeter, whereas the determination of the theoretical limit pressure needs its extrapolation to an infinite expansion and cannot be directly measured. The validation of this theory is made by the finite element method with the results of the Tresca standard model of Plaxis, which is compared with the theoretical expression. Some conclusions are drawn on the validity of this new theory which allows the measurement and the control of shearing modulus and shear strength of the natural soil.

3

Méthodes de reconnaissance croisées pour l'analyse de stabilité des digues soumises a erosion interne

Monnet J., Plotto P.

Studia Geotechnica et Mechanica

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2008

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Vol. 30, nr 1-2

21-30

EN

The sections of dam around Grenoble are the subject of a geotechnical campaign based on the use of a geophysical method, the electrical panel. Practice shows that the detection of the seepage, heterogeneities, the geometry, the nature of the layers obtained by the electric analysis is not always in conformity with an objective reality, but that the method of inversion leads to an uncertainty which can be important. Research allows us to reduce the errors of this method by taking into account of the geometries when they are known. Pressuremeter tests with cycle were carried out and interpreted in inverse analysis to determine the mechanical characteristics of elasticity and resistance with the methods developed with the L3S-R. Lefranc tests, for the determination of the permeability of materials of the dam, were also carried out. The results are gathered and compared with measurements in laboratory for a better analysis of the risk of instability.

4

Validation of an elastoplastic theory of the pressuremeter test in granular soil

Monnet J.

Studia Geotechnica et Mechanica

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2007

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Vol. 29, nr 3-4

69-80

EN

The recent elastoplastic pressuremeter theory of MONNET and KHUF [12] for the granular soil has been used in several civil engineering constructions. The finite element method allows nowadays the validity of this theory to be checked. In the first palt of tlle paper, we bliet1y present the interpretation of the pressuremeter test in granular soil and a theoretical expression of the limit pressure. In the second part, we present the analysis of tlle theoretical limit pressure versus the result of the Mohr-Coulomb non-standard model used by the Plaxis finite element program. As the theory shows that the limit pressure depends on four parameters, we apply a variation of one of these parameters, the others remaining unchanged, and we study the resulting variation of the limit pressure. TIle theoretical evolution of the limit pressure as a function of each parameter shows a fine agreement with the numerical results.

PL

Opracowaną przez MONNETA i KHLIFA [12] sprężystoplastyczną teorię testu presjometrycznego dla ośrodków sypkich wykorzystuje się w zagadnieniach inżynierii budowJanej. Potwierdzeniem teorii są rozwiązania, które umożliwia metoda elementów skończonych. W pierwszej części pracy- przedstawiono zastosowanie presjometru dla ośrodków sypkich oraz teoretyczny wzór naprężenia granicznego. W drugiej części analizowano teoretyczne naprężenia graniczne, porównując je z wynikami niestandardowego modelu Mohra-CouJomba za pomocą programu metody elementów skończonych Plaxis. Jak wykazuje teoria, naprężenie graniczne zależy od czterech parametrów. Zastosowano zmianę jednego z parametrów i, zakładając niezmienność pozostałych, analizowano zmiany naprężeń granicznych. Otrzymane teoretyczne zmiany naprężeń granicznych jako funkcje każdego z parametrów wykazały dobrą zgodność z rozwiązaniem numerycznym.

5

The uses of the pressuremeter test for the design of North Transversal Tunnel in Grenoble

Chapeau C., Dembicki E., Kurek N., Marbach G., Monnet J.

Archives of Civil Engineering

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2006

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Vol. 52, nr 1

87-104

EN

The tunnel's construction in urban area is a particularly sensitive problem due to the careful security requirements, which must be applied to prevent tunnel from failure and from large displacements and to avoid damage to existing buildings. The tunnel of the North Transversal Road of Grenoble begins from Sablon district, crosses under river Isere, passes under Ile Verte district, crosses a second time under river Isere and joins the motorway A48 at Porte de France, and A480 at Pont du Vercors. In this area alluvial soils are observed with silty sands and clays and rock with the Chartreuse limestone. Along the tunnel construction the different layers of the soil were studied. Deformation and failure parameters are measured by cyclic and standard pressuremeter tests with push in slotted tube probe because sampling of silty sands under the water table is very difficult. The tests are used to determine the angle of friction of the soil, the cohesion of the clay and the Young's modulus. The results of the pressuremeter tests are used for the statistical calculations with the EXTREME program, which determine the mean value X, the standard deviation, the characteristic value Xk, and the theoretical distribution of each parameter. The characteristic values of the angle of friction for each families of the soil are computed. Characteristic values are calculated so that there is a probability (equal to 5%) that a new experimental value would be smaller than angle of friction. The Normal, Log Normal, Exponential, Weybull, Gamma, Chi2, Student, Pareto distributions are tested and are checked by the Anderson-Darling ( A-D ) test. The data variability of the geomechanical parameters is taken into account for the design of the project and for the safety of the tunnel drilling.

PL

Wykonanie konstrukcji tunelu w strefie mocno zurbanizowanej jest szczególnie trudnym zagadnieniem. Dlatego też należy spełnić liczne wymagania aby zapobiec zniszczeniu tunelu jak również istniejących budynków. Tunel będzie przebiegał przez okręg Sablon przecinając rzekę Isere, okręg Ile Verte oraz po raz drugi rzekę Isere a następnie zostanie przyłączony do autostrady A48. W tym obszarze obserwuje się grunty aluwialne nanoszone przez rzekę z przewarstwieniami mułów, glin oraz wapieni Chartreuse. W strefie gdzie ma przebiegać tunel wykonano badania parametrów gruntu za pomocą presjometru używając standardowej procedury obciążenie-odciążenie. To pozwoliło wyznaczyć kąt tarcia wewnętrznego, spójność oraz moduł Young'a. Wyniki otrzymane z badań presjometrycznych wykorzystano do obliczeń statystycznych za pomocą programu Extreme, który wyznacza wartość średnią X, odchylenie standardowe, wartość charakterystyczną Xk i rozkład teoretyczny każdego z parametrów. Obliczono wartość charakterystyczną kąta tarcia wewnętrznego dla każdej rodziny gruntów z prawdopodobieństwem (równym 5%), że nowa wartość doświadczalna będzie mniejsza niż kąt tarcia wewnętrznego. Badano rozkłady: normalny, log normalny, wykładniczy, Weybull, Gamma, Chi2, Student, Pareto, które sprawdzono testem Anderson-Darling. Zmienność parametrów geotechnicznych uzyskanych z obliczeń statystycznych przyjęto do projektu tunelu.

6

The foundation of the Crozet bridge. A case study

Monnet J., Billet P., Allagnat D., Teston J., Baguelin F.

Studia Geotechnica et Mechanica

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2005

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Vol. 27, nr 1-2

125-142

EN

The Crozet bridge is located on the Grenoble-Col du Fau motorway, in the Grenoble-Sisteron intinerary, fifteen kilometres south of Grenoble, Frace. It crosses a 350 m wide valley and the RN75 national road. The adaptation of the bridge to the lanscape has involved an arch design with three bays (direction of Grenoble-Sisteron) and one bay (direction of Sisteron-Grenoble). The supports of the structure were difficult to build because of a huge horizontal force and a low displacement tolerance. The low stiffness and strength characteristics foreseen led to a geotechnical investigation by cyclic pressuremeter tests with a friction angle and cohesion interpretation. The foundation calculations were carried out by the CESAR-LCPC program to determine the support rigidity. A complete computation of the bridge was done with the calculated support rigidity which showed that displacements of the arches were lower than the tolerance limit. The bridge is located in the area of low seismic activity and the design takes into account the maximum foreseeable magnitude. The soil liquefaction risk was analysed as well. Monitoring carried out for completion of the bridge in 1999 and along the surveying shows displacements lower than tolerance values. Since 1999, the bridges has withstood huge service weights without any difficulty.

7

Badania laboratoryjne nowego przyrządu terenowego: geomechametr

Dembicki E., Kurek N., Monnet J., Senouci S. M.

Inżynieria Morska i Geotechnika

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2005

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nr 3

201-208

PL

Nowe urządzenie do badań parametrów gruntu o nazwie geomechametr. Siły ciśnienia spływowego generowane przez przepływ wody wokół sondy pomiarowej. Zmiana składowej pionowej naprężenia na badanym poziomie. Pomiar czterech charakterystyk mechanicznych gruntu: moduł ścinania, kąt tarcia wewnętrznego, współczynnika filtracji i współczynnika konsolidacji.

EN

The paper presents new in situ apparatus to test the soil parameters which is called the geomechameter. Using the forces generated by water flow around the measurement probe. The hydraulic flow allows the variation of the vertical stress, at the test level. Geomechameter can measure four soil mechanical characteristics: the elastic shear modulus, the internal angle offriction, the coefficient of permeability and consolidation coefficient.

8

Dimensionnement d'un grand mur de soutenement par reconnaissance pressiometrique

Monnet J., Allagnat D.

Studia Geotechnica et Mechanica

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2004

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Vol. 26, nr 1-2

3-13

PL

Autostrada A51 biegnie wzdłuż rzeki Isere blisko Teche, między Grenoble a Valence, i dlatego potrzebny jest tam duży mur oporowy. Konstrukcję tę zrobiono, opierając się na pomiarach presjometrycznych. Testy presjometryczne przeprowadzono, korzystając z sondy, którą wciskano w glebę. Nowej teorii presjometrycznej użyto, aby określić wewnętrzny kąt tarcia gliny. Otrzymane wyniki umożliwiły przystosowanie muru do środowiska geotechnicznego i oszacowanie wewnętrznego kąta tarcia.

EN

The A51 motorway is going along the river Isere near Teche, between Grenoble and Valence and a large retaining wall was needed. This is an anchor wall. The design was made based on pressuremeter measurement. The pressuremeter tests were carried out with lantern probe that was pushed in the soil by dynamic driving. A new pressuremeter theory was used for finding the internal angle of friction of the loam. The results allowed the adjustment of the wall to the geotechnical environment and to evaluate the internal angle of friction.