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Yokoyama H.,Geology Laboratory | Izumi Y.,Architecture Laboratory | Watanabe T.,Structural Mechanics Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2016

The analysis of the whole model of train-induced vibration, which consists of the moving train, the track, the supporting infrastructure, the ground, and the building, is currently too large to solve. We thus proposed a numerical simulation method by combining two separate dynamic analysis models. One is an analysis model of the dynamic interaction between the moving train and the track-structure system for calculating excitation force. The other is a three dimensional dynamic analysis model of the supporting structure, the ground, and the building for calculating the propagation of vibration. © 2016, Ken-yusha Inc. All rights reserved.


Kato S.,Geology Laboratory | Kamohara A.,Geology Laboratory | Yokoyama H.,Geology Laboratory | Iwata Y.,Geology Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2014

Areas on each side of overbridges in embankment sections form border zones between the embankment and the girder, where ballast support rigidity varies, and track subsidence tends to occur. Investigations were thus conducted into the influence that ballast support rigidity variation and track subsidence can have on dynamic forces and the characteristics of ground vibration propagation, by means of a parameter study using dynamic analysis models. The effect was also evaluated of countermeasures for ground vibrations generated around the girder.


Hasegawa A.,Geology Laboratory | Ohta T.,Geology Laboratory
Quarterly Report of RTRI (Railway Technical Research Institute) | Year: 2013

In recent years, railways have suffered frequent damage from landslides due to natural slopes adjoining tracks. Checking the stability of all trackside slopes however would be immensely time consuming and expensive. Developing a practicable and viable method to manage such natural slopes is therefore important. This paper quantified the factors relating to landslides such as geomorphologic features and vegetation, using a digital elevation model and a digital surface model. These evaluation factors were then applied to identify potential landslide locations.


Adelinet M.A.,Geology Laboratory | Fortin J.F.,Geology Laboratory | Guaeguen Y.G.,Geology Laboratory | Schubnel A.S.,Geology Laboratory
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

We conducted hydrostatic experiments on a basalt specimen in both dry and saturated conditions. The investigated Icelandic basalt is characterized by a bimodal porosity, i.e., cracks and equant pores. The elastic properties-bulk moduli in our case-were investigated under high pressure through two experimental methods: (1) a classical one using ultrasonic P- and S-waves velocities (frequency 106 Hz), (2) and a new one, using oscillation tests (frequency 10-2 Hz). In dry condition, experimental data show no significant difference between high (HF) and low (LF) frequency bulk moduli. However, in saturated conditions, two effects are highlighted: a physico-chemical effect evidenced by a difference between drained and dry moduli, and a squirt-flow effect evidenced by a difference between HF and LF undrained moduli. We try to predict such a frequency dispersion from a theoretical point of view. An effective medium with cracks and pores is used for calculating the HF bulk and shear moduli. The LF moduli are obtained by taking the HF dry moduli and substituting into Gassman's equations. © 2010, European Association of Geoscientists and Engineers.


Fortin J.,Geology Laboratory | Stanchits S.,Helmholtz Center Potsdam | Dresen G.,Geology Laboratory | Gueguen Y.,Geology Laboratory
72nd European Association of Geoscientists and Engineers Conference and Exhibition 2010: A New Spring for Geoscience. Incorporating SPE EUROPEC 2010 | Year: 2010

Reservoir rocks can undergo irreversible deformation (dilatancy or compaction) as a result of a change in effective stress during production of hydrocarbon or during CO2 storage. In this study, we investigated the mechanical behavior of the Chauvigny limestone. It is one of the rocks, which constitutes the Dogger, a deep saline aquifer, one of the favorable geological reservoirs for CO2 storage in France. To investigate the brittle-ductile transition in this limestone, we performed triaxial experiments, at confining pressure in the range of 5-100 MPa. In addition, the evolutions of elastic wave velocities were measured periodically with loading. Our results show that diltatant (nucleation and propagation of cracks) and compaction micro-mechanisms (plastic pore collapse) compete. Two limit cases can be distinguished. During hydrostatic compression, the inelastic volumetric strain seems to be mainly associated with plastic pore collapse, whereas for the triaxial experiments at confining pressure < 30 MPa, the inelastic volumetric strain seems to be mainly associated with the development of shear-induced cracks. For the triaxial experiments at confining pressure > 30 MPa, we are able to distinguish a first critical stress state where plastic pore collapse occurs, and a second stress state where shear-induced cracks are initiated. © 2010, European Association of Geoscientists and Engineers.

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