Search Results

You are looking at 1 - 10 of 19 items for :

  • Mechanics and Fluid Dynamics x
Clear All
Open access

Małgorzata Jastrzębska, Marian Łupieżowiec, Rafał Uliniarz and Artur Jaroń

References [1] CIESIELSKI R., KWIECIEŇ A., STYPUŁA K., Vibrations Propagation in Subsoil Superficial Layers , Monograph, 263, Krakow University of Technology Publishers, 1999, (in Polish). [2] GRYCZMAŇSKI M., ULINIARZ R., A simple critical state model with small strain nonlinearity for overconsolidated soils , Foundations of Civil and Environmental Engineering, 2008, 12, 49-60. [3] JARDINE R.J., POTTS D.M., FOURIE A.B., BURLAND J.B., Studies of the influence of nonlinear stress-strain characteristics in soil structure interaction , Geotechnique, 1986

Open access

Wojciech Pakos

References [1] ŻÓŁTOWSKI K., Pedestrian on footbridge - loads and the response, Politechnika Gdańska, Gdańsk 2007. [2] PAKOS W., The experimental and theoretical analysis of active elimination of cables vibration in cable stayed footbridges, Unpublished doctoral dissertation, Politechnika Wrocławska, Wrocław, Poland, 2012, (in Polish). [3] PAKOS W., WÓJCICKI Z., Vibration control of a cable-stayed footbridge using the tension changes of cable, XXIII R-S-P seminar, Theoretical Foundation of Civil Engineering

Open access

Aneta Herbut

References [1] ALZAWI A., HESHAM E., NAGGAR M., Full scale experimental study on vibration scattering using open and in-filled (Geo- Foam) wave barriers, Soil Dynamics and Earthquake Engineering, 2011, 31, 306-317. [2] BS 5228-4:1992. British standard. Noise control on construction and open sites. Part 4: Code of practice of noise and vibration control applicable to piling operation. [3] BS 7385-2:1993. Evaluation and measurement for vibration in buildings. Part 2: Guide to damage levels from ground borne

Open access

Anna Borowiec and Krzysztof Maciejewski

Abstract

Liquefaction has always been intensely studied in parts of the world where earthquakes occur. However, the seismic activity is not the only possible cause of this phenomenon. It may in fact be triggered by some human activities, such as constructing and mining or by rail and road transport.

In the paper a road embankment built across a shallow water reservoir is analyzed in terms of susceptibility to liquefaction. Two types of dynamic loadings are considered: first corresponding to an operation of a vibratory roller and second to an earthquake.

In order to evaluate a susceptibility of soil to liquefaction, a factor of safety against triggering of liquefaction is used (FSTriggering). It is defined as a ratio of vertical effective stresses to the shear stresses both varying with time. For the structure considered both stresses are obtained using finite element method program, here Plaxis 2D. The plastic behavior of the cohesionless soils is modeled by means of Hardening Soil (HS) constitutive relationship, implemented in Plaxis software.

As the stress tensor varies with time during dynamic excitation, the FSTriggering has to be calculated for some particular moment of time when liquefaction is most likely to occur. For the purposes of this paper it is named a critical time and established for reference point at which the pore pressures were traced in time. As a result a factor of safety distribution throughout embankment is generated.

For the modeled structure, cyclic point loads (i.e., vibrating roller) present higher risk than earthquake of magnitude 5.4. Explanation why considered structure is less susceptible to earthquake than typical dam could lay in stabilizing and damping influence of water, acting here on both sides of the slope.

Analogical procedure is applied to assess liquefaction susceptibility of the road embankment considered but under earthquake excitation. Only the higher water table is considered as it is the most unfavorable.

Additionally the modified factor of safety is introduced, where the dynamic shear stress component is obtained at a time step when its magnitude is the highest - not necessarily at the same time step when the pore pressure reaches its peak (i.e., critical time). This procedure provides a greater margin of safety as the computed factors of safety are smaller.

Method introduced in the paper presents a clear and easy way to locate liquefied zones and estimate liquefaction susceptibility of the subsoil - not only in the road embankment.

Open access

Marek Wyjadłowski

REFERENCES [1] B oller C h ., Structural Health Management of Ageing Aircraft and Other Infrastructure , Monograph on Structural Health Monitoring, Inst. of Smart Structures and Systems, Bangalore, India, 2002. [2] B rząkała W., H erbut A., R ybak J., Recommendations for ground vibrations survey in course of geotechnical works , 14th International Multidisciplinary Scientific GeoConference SGEM 2014, GeoConference on science and technologies in geology, exploration and mining: conference proceedings, Albena, Bulgaria, 17–26 June, 2014. Vol. 2

Open access

Krzysztof Majcher

1 Introduction There are two basic methods in the structural dynamics: computational and experimental. Both these methods are equally important and used for both newly designed construction structures and the existing ones. The purpose of both methods is the same - they usually allow for determining the basic dynamic features of the structure (e.g., natural frequencies and their corresponding vibration modes, critical damping ratios) or for determining the level of construction effort (e.g., by determining the actual dynamic ratio). Computer programs based

Open access

Bogumił Wrana

References [1] ALLARD J.F., Propagation of Sound in Porous Media , Elsevier Science Publ., 1993. [2] BARDET J.P., The Damping of Saturated Poroelastic Soils during Steady State Vibration , Applied Mathematics and Computation, 67, 1995, 3–31. [3] BIOT M.A., Theory of Propagation of Elastic Waves in a Fluidsaturated Porous Solid. I. Low-frequency range , J. Acoust. Soc. Am., 28, 1956a, 168–178. [4] BIOT M.A., Theory of Propagation of Elastic Waves in a Fluidsaturated Porous Solid. II. High-frequency Range , J. Acoust. Soc. Am., 28, 1956b, 179

Open access

Irena Bagińska, Wojciech Janecki and Maciej Sobótka

Abstract

The paper deals with the methodology of performing and interpretation of seismic cone penetration test (SCPT). This type of test is used to determine velocity of the seismic wave in the soil medium. This study is focused on shear wave. The wave is triggered on the ground surface by hitting an anvil with a sledgehammer. Then, vibrations induced at different depths are measured. Based on recorded measurements wave velocity (Vs) and thus also small strain shear modulus Gmax may be calculated. An interpretation of exemplary seismic test results is presented. Crossover and cross-correlation methods are discussed and another, more adequate one is featured and then applied in the interpretation example. Conditions for correct test performance and interpretation are discussed.

Open access

Youcef Mahmoudi, Abdellah Cherif Taiba, Leila Hazout, Wiebke Baille and Mostefa Belkhatir

Abstract

The instability of saturated granular soils in field conditions generates drastic collapse in terms of runoff deformation because of its failing to sustain naturally applied loading conditions such as earthquakes, wave actions and vibrations. The objective of this laboratory investigation is to study the effects of the depositional methods, overconsolidation ratio (OCR) and confining pressure on the undrained instability shear strength of medium dense (Dr = 52%) sand–silt mixtures under static loading conditions. For this purpose, a series of undrained monotonic triaxial tests were carried out on reconstituted saturated silty sand samples with fines content ranging from 0% to 40%. Three confining pressures were used (P’c = 100, 200 and 300 kPa) in this research. The sand–silt mixture samples were prepared using two depositional methods, dry funnel pluviation (DFP) and wet deposition (WD), and subjected to two OCRs (1 and 2). The obtained instability lines and friction angles indicate that the funnel pluviated samples exhibit strain hardening compared to the wet deposited samples and that normally consolidated and overconsolidated wet deposited clean sandy samples were very sensitive to static liquefaction. The test results also indicate that the instability friction angle increases with the increase in the OCR expressing soil dilative character tendency increase. The instability friction angle decreases with the increase in the fines content for DFP and the inverse tendency was observed in the case of WD.

Open access

Dorota Pawlus

References [1] CHEN Y.R., CHEN L.W., Axisymmetric parametric resonance of polar orthotropic sandwich annular plates , Composite Structures, 2004, 65, 269-277. [2] CHEN Y.R., CHEN L.W., WANG C.C., Axisymmetric dynamic instability of rotating polar orthotropic sandwich annular plates with a constrained damping layer , Composite Structures, 2006, 73(2), 290-302. [3] CHEN Y.R., CHEN L.W., Vibration and stability of rotating polar orthotropic sandwich annular plates with a viscoelastic core layer , Composite Structures, 2007, 78, 45-57. [4] KLUESENER M