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.
The evaluation of stone column and jet grouting soil improvement with seismic refraction method: Example of Poti (Georgia) railway
Studies of surface improvement have been carried out in Georgia-Poti in order to decrease surface deformations since surface conditions of railway line that comes from the harbor are too poor. Stone column and jet grouting methods were evaluated together as surface improvement methods. As engineering parameters on the surfaces which are applied, jet grouting are higher than the other method, it was decided to improve the line within project with this method. This study was carried out in order to present surface parameters obtained with seismic refraction data carried out together with surface improvement practices. Findings show that parameters of shear wave velocity, amplification rate and bearing power obtained with jet grouting practices are higher than those of stone column practices. 
 
   
 
 Key words: Jet grouting, seismic refraction, soil improvement, stone column.
Evaluation and Control of Collapsible Soils
Some compacted soils wetted under certain conditions of compaction and loading may exhibit additional settlement (collapse). To investigate the effect of the soil type, compaction water content, initial dry unit weight and applied pressure at wetting on collapse potential, 138 single‐oedometer tests were conducted on eight different soils. The results indicate that well‐graded soils tend to collapse more than poorly graded ones under similar conditions. Furthermore, collapse potential decreases with an increase in (1) The difference between the sand and clay percentages; (2) compaction water content; and (3) initial dry unit weight, while it increases with pressure at wetting. A multiple regression analysis was performed on the laboratory results to provide a collapse‐predictive model that was substantiated by data reported by several researchers. A chart is presented to estimate (1) The collapse potential of soils under various conditions; and (2) the critical water content beyond which no collapse is ex...