Search

The potential of woodash to stabilize clay soil was evaluated. The evaluation involved the determination of the geotechnical properties of clay soil in its natural state as well as when mixed with varying proportions of woodash. The parameters tested included the particle size distribution, specific gravity, Atterberg limits, compaction characteristics, California bearing ratio (CBR) and the compressive strength. The CBR and strength tests were repeated after 28-day curing of the treated samples. Results showed that the geotechnical parameters of clay soil are improved substantially by the addition of woodash; plasticity was reduced by 35% and CBR and strength increased by 23–50% and 49–67%, respectively, depending on the compactive energy used. The highest CBR and strength values were achieved at 10% woodash. Results also showed that curing improved the strength of the woodash-treated clay. However, the strength gain was short lived as the strength quickly decreased after 7–14 days of curing. These results imply that although woodash provides some of the beneficial effects of lime in soil stabilization, such as plasticity and swell reduction, improved workability, and strength increase, it is unlikely to be a substitute for lime as strength gain is short lived. [ABSTRACT FROM AUTHOR]

Wave induced pore pressures in bottom soils have an influence on the geotechnical stability of structures and may also have an effect on the transport of sand. Wave induced pore pressures in a seabed of sand or clay has been an item for extensive research. One of the major difficulties in analyzing and interpreting both laboratory and field data has been related to the question of air/gas content in the pores of fine soil. Only a small fraction of air/gas significantly changes the bulk modulus of the water/gas mixture and also the attenuation of the wave induced pressures in the soil with depth. The reason for the difficulty of analyzing data has been the lack of good instrumentation for measuring the gas content in the seabed soil. [ABSTRACT FROM AUTHOR]

This paper presents the findings of a digital image analysis based study of clay fills, compacted with dynamic compaction for a building foundation in northeast Beijing, People’s Republic of China. Three levels of compaction energy were used at three compaction pits, respectively. Ground settlements and soil density increased with the number of dynamic impact blows. Microstructures of dry clay fill samples from the pits were examined with a scanning electronic microscope (SEM). Their microstructural parameters were further measured and analyzed quantitatively using digital image analysis. The clay SEM images are automatically converted into ternary images representing particles, pores, and contact zones for effective and efficient calculation of the clay microstructural parameters. The effect of dynamic compaction on the clay microstructural properties at different blow numbers and compaction energy levels is examined. Analysis revealed that the changes of the soil microstructural properties have a good correlation with the observed ground settlements at the three pits. The ground settlements are due to the size and shape changes and reorientation of the grain particles and pores of the clay fills. [ABSTRACT FROM AUTHOR]