IMPROVING SEISMIC RESISTANCE OF HYDRAULIC STRUCTURES USING SOIL IMPROVEMENT TECHNIQUES
Most of the Egyptian irrigation structures were built many decades ago. Most of these structures may be classified as unsafe structures when making an assessment of their resistance to earthquake loads in accordance with the current specifications. This research suggests a technique to increase the ability of these structures to resist seismic loads. The suggested technique depends on using soil improvement methods to improve the most stressed soil bulb zone under the structure. The effect of seismic site soil factor will be decreased by improving this part of soil. Controlled soil jet grouting technique could be used for the existing structures. Other types of soil improvement techniques such as soil mixing could be used for new structures or other types of earth structures. Numerical study was performed to investigate the feasibility of the suggested method. Experimental study was carried out to validate the numerical study. The dynamic responses of an improved location and normal location were measured. The two locations were subjected to the same excitation force. The measured responses were compared and evaluated. Based on the results of the suggested technique, a real site condition for an existing barrage structure was numerically analyzed before and after soil improvement to examine the suggested technique.
Microbial geo-technology in ground improvement techniques: a comprehensive review
Microbial geo-technology is an innovative eco-friendly technique that uses microbes to improve and strengthen weak or marginal soils. Bio-mediated ground improvement techniques have gained a lot of attention amongst researchers since the past decade. In this review article, an attempt has been made to investigate the different factors that affect the process of biological improvement overall including the type of microbes, quantity of microbes used, cementation solution molarity, pH of the system, treatment method, temperature, degree of saturation, density of soil, nutrient availability, etc. Enhancement in different properties of the treated soil as reported by other researchers was explored and investigated, and proper conclusions were drafted keeping all the factors into consideration. Identification of potential applications and challenges which could be faced in the in situ application of the technique was worked upon, and suggestions were provided. Finally, the limitations and future scope of microbial geo-technology were highlighted.
Silica in Soils1
Publisher Summary Silica in free and combined forms is a dominant component of the solid material of many soils, and dissolved silica is commonly a major solute of soil solutions. Breakdown of primary silicates, translocation of silica in solution, and deposition of secondary silica-containing substances are involved in the development of soils. Ions essential for the growth of plants are released to the soil solution as silicates weather, and these ions may be held against leaching at exchange sites on other silicates. Silica is absorbed in appreciable quantities by some plants and is returned to the surface of the soil as the plants decay. The nature and transformations of silica and silicates in soil are, thus, fundamental to an understanding of many aspects of soil and plant sciences.