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Kozawa T.,Kochi University | Onda A.,Kochi University | Yanagisawa K.,Kochi University | Chiba O.,Toda Co. | And 2 more authors.
Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan | Year: 2010

A simple thermal decomposition technique to convert asbestos-containing wastes (ACWs) into non-asbestos products has been developed by heating ACWs in a water vapor atmosphere. It was confirmed that cement slates containing 18 mass% chrysotile were converted into non-asbestos products by the thermal treatment in a water vapor atmosphere at 800°C for 2 h. In contrast, the thermal treatments in air required temperatures as high as 900°C to convert the cement slates into non-asbestos products. It should be noted that any chrysotile particles were not detected by the phase-contrast microscopic observation in the products after the thermal treatments in a water vapor atmosphere at temperatures beyond 800°C but three or less chrysotile particles remained after the thermal treatments in air at high temperatures beyond 900°C. In a water vapor atmosphere, ACWs were successfully converted into non-asbestos products at low temperatures below 800°C for 2 h by accelerated solid-state reactions between decomposed products of chrysotile and cement components to form calcium magnesium silicates. This technique may contribute to large-scale decomposition of ACWs with low energy consumption in comparison with the traditional melting method. © 2010 The Ceramic Society of Japan. Source


Mackay A.D.,Nishimatsu Construction Co. | Mackay A.D.,Formerly SMEC Asia Ltd.
Geotechnical Safety and Risk IV - Proceedings of the 4th International Symposium on Geotechnical Safety and Risk, ISGSR 2013 | Year: 2014

East Timor has an extensive road network often prone to land-sliding; typically this causes disruption to its transportation system which is the island's life line. The instability impacting the roads is mainly a combination of steep terrain; high annual precipitation, typical of a sub-tropical climates, and complex ground conditions affected by the tectonic uplift and deep weathering zones common throughout the island. Other influences affecting the susceptibility include erosion sensitivity and roads being placed on poorly prepared and un-compacted ground. Remedial measures against landslides have considered optimization of road alignment corridors; the avoidance of areas of concern, were possible, and a reduction in the reliance of traditional slope stabilization measures. Traditional stabilization measures have included stone pitching and gabion boxes, which have proven insufficient to support modern transportation frequency and load impacts. Up to date landslide stability evaluation has allowed assessment of landslide susceptibility for different ground conditions. Recommendations for suitable, regular maintenance with particular attention to effective road drainage networks have been based on this. Notwithstanding effective resource, with suitable training and allocation, is required to carry out this maintenance, and allocation using suitable construction materials, sourced from suitable locations as needed. This paper provides an overview of the road network throughout East Timor and factors affecting the landslide susceptibility, such as precipitation, terrain and the geological conditions. Details of some of the landslides, representing different types of susceptibility, impacting the roads are presented, with suggested slope stability mitigation measures for each representative landslide. © 2014 Taylor & Francis Group, London. Source


Watabe Y.,Port and Airport Research Institute | Imamura S.,Nishimatsu Construction Co. | Tsuchida T.,Hiroshima University
Indian Geotechnical Journal | Year: 2013

In order to improve the seismic capacity of a caisson type quay wall, lightweight backfill method is often used in practice. However, the interaction between the caisson and lightweight backfill is not yet clear due to its high complexity. In this study, a series of centrifuge shaking tests, in which a strong model box was used with the model ground made of relatively dense sand, was conducted to investigate failure mechanism, earthquake induced earth pressure, force equilibrium, etc. Width of the lightweight backfill was varied as a parameter. In the case with sand backfill, active failure in the backfilled sand occurred, while in the cases with lightweight backfill, two independent active failures occurred in the sand regions behind the lightweight backfill and caisson. Horizontal displacement of the caisson during seismic shaking was significantly decreased by lightweight backfill, because earth pressure between the caisson and backfill was reduced. Effect of the inverted trapezoidal lightweight backfill to decrease the horizontal displacement is much higher than that of the rectangular lightweight backfills, when the slope of the inverted trapezoid is milder than that of active failure surface in the sand. © 2013 Indian Geotechnical Society. Source


MacKay A.D.,Nishimatsu Construction Co.
Scour and Erosion - Proceedings of the 7th International Conference on Scour and Erosion, ICSE 2014 | Year: 2015

Oil and gas pipelines were installed for an 800 kilometre (km) distance across Sakhalin Island, east Russian Federation from 2005 to 2009. The pipelines ran between the oil and gas fields, located off the north east coast at Piltun, to the southernmost port at Kosakov for onward distribution. Amongst the challenges for these installations was the 120km hilly terrain, referred to as the Makharov Mountains, occupying the entire width of the island towards the south. As this terrain has undergone relatively recent formation and mainly comprised relatively weak sedimentary rock water run off had dissected the terrain forming steep sided “V” shape valley profiles as the mountains progressively uplifted. This paper provides an overview of the ground conditions across the Makharov Mountains, Sakhalin Island and the hydrological characteristics of the stream courses crossing the alignment. Particular attention is given the inspections carried out and how these were used to assess suitable river erosion protection measures. © 2015 Taylor & Francis Group, London. Source


Matsumoto T.,Kanazawa University | Nemoto H.,Research Center andrporation | Mikami H.,Sumitomo Mitsui Construction | Yaegashi K.,Hazama | And 2 more authors.
Soils and Foundations | Year: 2010

A series of experimental and analytical studies on the behaviours of model pile groups and model piled rafts in dry sand subjected to static vertical loading and static cyclic horizontal loading were carried out in order to investigate the influence of various pile head connection conditions between the raft and the piles on the behaviours of the foundations models and to examine the applicability of an simplified analytical method to simulate the load tests. In the load tests, the behaviours of the model foundations were investigated in detail, with particular focus on cyclic horizontal loading, and behaviour such as horizontal stiffness and the rotation of the foundation, the load proportions between the raft and the piles, and the bending moments and shear forces generated in the piles. A simplified three-dimensional deformation analysis method was used to simulate the experiments. Source

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