USE OF CONE PENETRATION TEST IN PILE DESIGN

Modern methods of pile design often make extensive use of `in situ´ test data. Different pile capacity prediction methods were used to evaluate the axial capacity of 13 full-scale test piles. The pile load tests were performed on CFA piles in various soil conditions. The predicted behaviours of the piles are discussed and compared with the results of the pile load tests

Analysis of Seismic Fragility Functions of Highway Embankments

Vulnerability assessment of structures is a vitally important topic among earthquake engineering researchers. Generally, their primary focus is on the seismic performance of buildings. Less attention is paid to geotechnical structures, even though information about the performance of these structures (e.g. road embankments, levees, cuts) during an earthquake is essential for planning remediation and rescue efforts after disasters. In this paper the seismic fragility functions of a highway embankment are defined following an analytical methodolgy. The technique is a displacement-based evaluation of seismic vulnerability. Displacements of an embankment during a seismic event are approximated by a 2-D nonlinear ground response analysis using the finite element method. The numerical model was calibrated based on the results of a 1-D nonlinear ground response analysis. The expected displacements were calculated for 3 different embankment heights and Peak Ground Acceleration (PGA) values between 0,05 and 0,35g. Based on the results of the 2-D finite element analysis, the relationship between displacements and different seismic intensity measures (PGA, Arias-intensity) was investigated. Different damage states were considered, and the probability of their exceedance was investigated. The seismic fragility functions of the embankments were developed based on probability of exceedance of these different damage states based on a log-normal fragility function. The legitimacy of using a log-normal fragility function is also examined

Estimation of CPT resistance based on DPH results

Hungarian experience about the correlation of CPT and DPH results is summarized. A historical review of CPT-DPH and CPT-SPT correlations is presented, and the reliability of the published CPT-DPH correlations is analyzed using recent data from Hungarian geotechnical practice. Based on these data the paper defines soil types where reliable correlation exists and proposes formulas describing the relationships between the CPT and DPH results, because in the case of hard state clays and soils containing gravel an acceptable relationship cannot be stated

Comparison of Different Empirical Correlations to Estimate Permeability Coefficient of Quaternary Danube Soils

Permeability coefficient is the most significant soil parameter in seepage calculations. It has been recognized that permeability of granular soils is strongly related to the grain size, thus numerous empirical correlations have been developed to estimate permeability using its grain size characteristics. In this study the empirical correlations proposed by Hazen (1911), Carrier (2003) and Chapuis (2004) are evaluated and compared to laboratory measurement results. Quaternary Danube soils are very typical in the Carpathian basin, thus their permeability is an important question in many geotechnical applications

A Study on the Relationship Between Matric Suction and the Void Ratio and Moisture Content of a Compacted Unsaturated Soil

The volumetric behaviour of compacted unsaturated soils is particularly complex due to the co-existence of three different phases: solid, liquid and air. Matric suction has been perceived as a significant influence on the volumetric behaviour of unsaturated soils and has been used as one of the constitutive variables for most the constitutive models of unsaturated soils in the literature. However, suction-controlled works are complex in practice since they generally require special test procedures and advanced equipment, and usually are very time-consuming. Thus, some researchers have tried to seek alternative frameworks that use the traditional choice of state variables to simulate the behaviour of unsaturated soils. Recently, Kodikara [1] proposed the MPK framework to interpret the behaviour of compacted unsaturated soil in the void ratio (e) – net stress (p) – moisture ratio (ew ) space. The distinct advantage of the model is that it is based on traditional constant moisture content compaction testing which is more common and simple than constant suction loading. The MPK framework has been shown to be capable of presenting the volumetric behaviour of compacted unsaturated soils. However, this framework is expected to use not only for compacted soil but for the behaviour of unsaturated soil in general. The incorporation of soil suction within the MPK framework can be helpful for creating a correlation with previous models which used matric suction as a constitutive variable. This paper presents the development of LWSBS for one clayey soil in Hungary within the MPK framework and then suction is incorporated, which is related to void ratio and moisture ratio through SWCC

Three Dimensional Finite Element Analysis of Deep Excavations’ Concave Corners

The behavior of deep excavation’s retaining structures may become rather complex near the corners. The vicinity of concave corners is an especially problematic zone, and causes numerous problems in everyday practice. Conventional 2D analyses considering axisymmetric or plane strain conditions cannot be used in such cases due the spatial nature of the problem. A set of three dimensional finite element analyses have been performed aiming better understanding of soil and structure behavior near excavations’ concave corners and evaluating the influence of corner angle. The bending moment arising in anisotropic diaphragm walls near the concave corners are summarized, and compared to 2D plane strain and axisymmetric results

Analysis and Finite Element Modelling of Water Flow in Concrete

Due to the construction of underground structures and hazardous waste storages, understanding and modelling of seepage in concrete has become an important issue in life-span analyses. The theories and calculation methods of unsaturated soil mechanics provide an opportunity to analyze water flow in other types of porous media (e.g. concrete) as well. This study deals with the determination of the permeability for unsaturated and saturated concrete and modelling the water flow in concrete. The direct measurement of the saturated permeability, the preparation of the drying water retention curve and determination of the depth of penetration of water under pressure are involved in the series of tests. For the fitting method of the experimental water retention curves were used Fredlund and Xing (1994) and van Genuchten (1980) model. The theory of lateral shift was applied to estimate the wetting water retention curve from the drying WRC. Thus, we could calculate the unsaturated permeability functions with Fredlund et al. (1994) and van Genuchten (1980) model. The finite element modelling of the standard test for watertightness were performed with Midas GTS using the measured and calculated unsaturated property functions

Közúti infrastruktúra elemeinek szeizmikus teljesítőképességének vizsgálata

Hazai gyakorlatban a földrengésre való méretezést az Eurocode-8, illetve annak nemzeti mellékletei szabályozzák, melyek a különböző infrastruktúra szerkezetek méretezése során első sorban a tönkremenetellel szembeni biztonság meghatározását célozzák. A különböző infrastruktúra és vízépítési műtárgyakhoz kapcsolódóan a szerkezetek használhatósága már a tönkremenetelt megelőzően is korlátozódhat, ezért a biztonsági tényező meghatározása mellett fontos a szeizmikus teher hatására történő várható elmozdulások és a szeizmikus teljesítőképesség ismerete is. Az elmozdulásokat talajválasz elemzés eredményeként határozhatjuk meg. A különböző elmozdulásokat a károk mértékétől függően károsztályokba sorolva, az egyes károsztályok meghaladási valószínűségét meg lehet határozni. Ezt a meghaladási valószínűséget különböző intenzitású szeizmikus hatások esetére a sérülékenységi görbék fogják jellemezni. Cikkünkben bemutatjuk a talajválasz elemzés lehetséges módszereit, különös tekintettel a véges elemes módszerekre, majd egy esettanulmányon keresztül bemutatunk egy, a sérülékenységi görbék meghatározását célzó módszertant

A Visco-hypoplastic Constitutive Model for Rolled Asphalt

Experience has shown that the durability of “high-modulus” asphalts made with modified bitumen is unsatisfactory. The misdirected “development” forced in recent decades necessitates a more accurate understanding of the mechanical behavior of rolled asphalts, i.e., constitutive formulation of a numerical asphalt model. The authors elaborate a numerical procedure to model the visco-hypoplastic constitutive behavior of the rolled asphalts by the appropriate composition of the hypoplastic theory of soil mechanics and, taking into account the existing asphalt models. This proposal is justified because rolled asphalt is nothing more than an aggregate skeleton of mineral origin, the voids of which are filled with high-viscosity bitumen. The model allows to quantify the interaction of the two components, such as the formation of ruts due to pressure on the bitumen, the formation of cracks due to cooling-induced tensile stresses, and the viscous behavior of asphalt. Validity of this complex numerical model can already be considered proven theoretically, but it still needs to be experimentally verified for the viscous behavior. This new constitutive model has important theoretical and practical consequences such as a new visco-hypoplastic model of rolled asphalt as partially saturated granular material with cooling-induced isotropic residual stresses