Attenuation Characteristics of Ground Strains Induced During Earthquake

The appropriate estimation of ground strains Induced during earthquake is indispensable for the seismic design of buried lifeline facilities such as pipeline systems. The ground strains induced during earthquakes are calculated with use of the dense instrument array data observed during past 78 earthquakes for the surface ground at the Public Works Research Institute (PWRl) ln Tsukuba Science City in Japan. Based on the multiple regression analysis for the calculated ground strains, the empirical formulae of attenuation of maximum ground strains for such the ground condition as the PWRI campus are proposed ln terms of earthquake magnitude and epicentral distance, and the attenuation characteristics of ground strains are investigated

Soil Liquefaction Potential Evaluation with Use of the Simplified Procedure

A simplified method based on both a liquefaction resistance factor, FL and a liquefaction potential factor, PL has been proposed for evaluating soil liquefaction potential. The factor FL indicates the liquefaction potential at a given depth of a site, and the factor PL indicates the one at a site. The effectiveness of the proposed method is investigated by calculating the factors FL and PL at both liquefied and non-liquefied sites during past typical earthquakes in Japan, and carrying out shaking table tests

Experimental Study on Lateral Flow of Ground Due to Soil Liquefaction

A series of shake table tests is carried out on the lateral flow of the ground due to soil liquefaction during earthquakes. The model grounds are 6.0 m long, 0.8 m wide and their average height is 1.2 m. The slope of the ground surface and the lower boundary condition of liquefiable layer are varied, and the sinusoidal accelerations with a frequency of 2 Hz are inputted for 20 seconds. The deformation of model grounds, the excess pore water pressure of the liquefied layer, and the acceleration of the grounds are monitored. Based on the test results, the influence of the slope, the input motion and the thickness of liquefied layer to the ground flow is examined, and the fundamental characteristics of lateral ground flow induced by soil liquefaction are clarified experimentally

Effectiveness of Compaction Grout Piles in Improving Foundation Soils of Existing Runway

Compaction grout piles were used to minimize the liquefaction potential of the foundation soils of Tokyo International Airport at the intersection area of the two runways A and B. The compaction grout piles were intermittent to treat only the liquefiable soil layers and of varying diameter to account for the variable condition of the treated soils. This paper describes the performed grouting works and presents improvement results for one of the grouting stages. The presented results reveal the effectiveness of the adopted design and procedure in improving the liquefiable soils. The paper also discusses the improvement results with emphasis being on the obtained improvements at the vertical boundaries of the treatment zones. The discussion suggests that there is a loss of improvement at the boundaries and this loss is attributed to the boundary effect and the effect of variation of soil compressibility around the boundary of treatment zone. A correlation between a newly presented index called relative compressibility index (RCI) and the improvement at the boundary is identified. This correlation is useful in planning the intermittent treatments by compaction grout piles and implies that the loss of soil improvement at the boundary of treatment zone increases as RCI decreases

The competitiveness of domestic rice production in East Africa: A domestic resource cost approach in Uganda

The rapid increase of rice imports in sub-Saharan Africa under the unstable situation in the world rice market during the 2000s has made it an important policy target for the countries in the region to increase self-sufficiency in rice in order to enhance food security. Whether domestic rice production can be competitive with imported rice is a serious question in East African countries that lie close, just across the Arabian Sea, to major rice exporting countries in South Asia. This study investigates the international competitiveness of domestic rice production in Uganda in terms of the domestic resource cost ratio. The results show that rainfed rice cultivation, which accounts for 95% of domestic rice production, does not have a comparative advantage with respect to rice imported from Pakistan, the largest supplier of imported rice to Uganda. However, the degree of non-competitiveness is not serious, and a high possibility exists for Uganda’s rainfed rice cultivation to become internationally competitive by improving yield levels by applying more modern inputs and enhancing labour productivity. Irrigated rice cultivation, though very limited in area, is competitive even under the present input-output structure when the cost of irrigation infrastructure is treated as a sunk cost. If the cost of installing irrigation infrastructure and its operation and maintenance is taken into account, the types of irrigation development that are economically feasible are not large-scale irrigation projects, but are small- and microscale projects for lowland rice cultivation and rain-water harvesting for upland rice cultivation