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.
DESIGN CONCEPT OF THE SOIL IMPROVEMENT FOR ROAD CONSTRUCION ON SOFT CLAY
This paper presents an innovative use of soil-cement mixing method using jet grouting technique to improve the bearing capacity of subbase foundation for road construction in Thailand. The construction sequences and the basic design example of jet grouting for embankment works on soft clay are also given in this paper. The design concept and method of analysis of jet grouting work using finite element technique, results of finite element analysis, the installation adopted and effectiveness of soil improvement system are given and discussed. It was found that the total settlement is reduced by the jet grouting. A case history at Pak Phanang Diversion Dam project, Nakornsrithamarat, Thailand is presented describing the engineering design and construction aspects of a successful project, which demonstrated the advantage of soil-cement mixing method over conventional pile driving for this site.
A field trial of jet-grouting in marine clay
The basement excavation of the Singapore Post Center involved extensive jet-grouting to improve the soft marine clay present within the excavation. The treated soil mass, with much improved strength and deformation characteristics, was intended to act as an internal strut below the bottom of the excavation level, reducing movements caused by the basement excavation. This paper presents the performance of a well-instrumented field jet-grouting trial during the construction of the building basement. Results of monitoring suggest that the jet-grouting trial caused the retaining diaphragm walls and the adjacent soils immediately behind and at some distance away from the walls to move away from the jet-grouted area. The maximum free field lateral soil movements in the excavation side of the jet-grouted mass were much larger than the corresponding lateral movements behind the wall. The results suggest that the diaphragm wall provided considerable restraint, thereby reducing the lateral movements of the soil beh...