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Shahin H.M.,Islamic University of Technology | Nakai T.,Geo Research Institute | Ishii K.,Kajima Corporation | Iwata T.,West Corporation | Kuroi S.,Okumura Corporation
Acta Geotechnica

To investigate the realistic ground behavior during tunneling, a new device has been developed. With the new device, model tests of tunnel excavation considering an existing tunnel and an existing building were carried out. Non-linear finite element analyses corresponding to the model tests were also conducted using FEMtij-2D software where an elastoplastic subloading tij model was used to describe the mechanical behavior of soil. Earth pressure distribution around the tunnels and ground movements during tunnel excavation depend on the distance and position between the twin tunnels. There is a significant effect of tunneling on the existing foundation of building even in the case where the tunnel is constructed in deep underground. The numerical analyses capture well the results of the model tests. © Springer-Verlag Berlin Heidelberg 2016. Source

Sano N.,University of Tsukuba | Kanakubo T.,University of Tsukuba | Yasojima A.,University of Tsukuba | Hosoya H.,Okumura Corporation
AIJ Journal of Technology and Design

In this study, the loading test of precast concrete beam-column joints using DFRCC in joint panel is conducted to evaluate effect of preventing crack widening and structural performance of joint panel with DFRCC. The experiment factor is shear reinforcement arrangement in joint panel. The test results are compared with those of conventional concrete specimen with same reinforcement arrangement in previous experiments. From the experiment results, it can be recognized that DFRCC improves the shear performance of precast concrete beam-column joints and confinement effect of DFRCC is the same or higher than that of shear reinforcement. Source

Takeda A.,Okumura Corporation | Yamamoto H.,Hiroshima University
AIJ Journal of Technology and Design

This paper presents the results of pile construction work for two steel-frame buildings. These buildings incorporate a method proposed by the authors in which the bottom end of a steel column is directly connected to the top end of a precast concrete pile. This method, which was developed for the construction of low-rise, long-span, steel-frame buildings, obviates the need for pile caps and underground beams. This method, however, requires greater accuracy pile construction than is required with conventional construction method. Hence, a stringent construction control value was specified for the work, and the outcome satisfied this value. Source

Otsuka Y.,Okumura Corporation | Katsumi T.,Kyoto University
15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability

Management of disaster debris treatment may include (1) progress in several work with over 100 laborers, (2) control of various mechanical equipment and machineries, (3) operation of more than 200 trucks. In order to properly support this management, Okumura Corporation has developed the "Disaster debris Treatment Support System (DTSS)" in 2011. DTSS has been accumulated a large amount of integrated data on disaster debris treatment in Yamada town, Iwate prefecture. 240,000 unit data obtained by the DTSS were analyzed to reveal the physical properties of debris and tsunami deposits. These data were too huge to analyze effectively. Spreadsheet software usually cannot be calculated 100,000 or more data. We solved this problem by applying a practical analysis software. The software called "Tableau" can be efficiently analyzed 100,000 or more data. The huge data was analyzed with Tableau. Results of the analysis of applying the Tableau revealed several weight characteristics of the transport phase in the debris and tsunami deposits. The results obtained will be expected to effective use as an experience to the time of future catastrophe. Source

Shahin H.M.,Nagoya Institute of Technology | Nakai T.,Geo Research Institute | Kuroi S.,Okumura Corporation
15th Asian Regional Conference on Soil Mechanics and Geotechnical Engineering, ARC 2015: New Innovations and Sustainability

Two-dimensional model tests of shallow tunnels and the corresponding numerical analyses were carried out to investigate the interaction between the tunnel excavation and the adjacent foundation. The existing building loads are applied on the ground considering pile foundation. Here, the interaction effects are investigated varying the lateral distance between the tunnel and the foundation. The model tests were conducted using a newly developed device to simulate circular tunnel excavation. Non-linear finite element analyses corresponding to the model tests are also conducted using FEMtij-2D software where the subloading tij model is used as a constitutive model of soil. Surface settlement and shear strain of the ground, and earth pressure around tunnel are investigated. It is found that tunneling influences on the existing foundation when super structure exists within a certain distance from the tunnel. Source

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