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.
STRENGTHENING AND REHABILITATION TECHNIQUES FOR MASONRY HYDRULIC STRUCTURES-A CASE STUDY ( PART 1-ASSESSMENT )
Barrages are considered one of the most important water structures in Egypt. It is very important to keep them working in good condition to assure water management in good manner. Most of these barrages have been built many decades ago using burned clay bricks and still in service till now. The construction cost of new barrages is very expensive, so, maintaining, repairing and strengthening these structures are an economical option that cannot be ignored. Many reasons cause defects in masonry hydraulic structures. These defects affect the structure capacity and performance. The causes of defects should be understood to be treated in optimum way. Structure assessment is the basic step to restore the structural capacity and to assign the suitable repairing technique. The aim of this paper is to present guidelines for the assessment of the masonry barrages when repairing, strengthening or upgrading is required. This could be achieved through reviewing the international experience in that field beside the gained experience from the many barrages upgrading projects. The paper displays a case study for assessment process for a typical masonry barrage type in Egypt. This study provides a solid basis for integrating all the monitored/output data into practical assessment of barrage system performance.The results of this study can also help to develop the current design codes.
On the use of the Hardening Soil Small Strain model in geotechnical practice
This article highlights the importance of using advanced constitutive soil models in numerical modelling as daily geotechnical practice. In this context, the Hardening Soil (HS) model is presented as the most advanced soil model implemented in the ZSoil finite element code. The article recalls the basic features of the HS model and it explains their role in numerical simulations. The role of pre-failure non-linear behaviour of soils is also discussed. An application of the HS model is illustrated on typical geotechnical problems such as retaining wall excavation, tunnel excavation and undrained loading followed by consolidation.