Ehsan Taherabadi Eliyas, ,
Volume 13, Issue 5 (12-2019)
Abstract
This paper investigates the effect of micropile installation into saturated sandy soil by means of finite element method. The obtained results from numerical modeling are compared with the received data from the site. The validation of software has been done by simulating standard penetration test. The effect of some changes in spacing (3m, 1.6m and 0.8m) and injection pressure (1cm, 2.5cm, 5cm and 10cm boundary displacement) micropiles on liquefaction behavior was discussed. The results show that numerical modeling presented a conservative conclusion about the potential of liquefaction. The modification of soil increased by increasing injection pressure of grout. Also, it was observed that the effect of micropile spacing has less impact than the injection pressures up to 1m free distance of micropiles. Then for closer micropiles, the effect of spacing and the effect of pressure became bold and intensive, respectively. Because of direct relationship between number of SPT and liquefaction potential, it would be necessary to simulate SPT and to validate with the real data, before and next of micropile installation. This approach can be a proper way of forecasting the efficiency degree of modification by micropiles and could save costs and time.
Mr. Mohammad-Emad Mahmoudi-Mehrizi, Prof Ali Ghanbari,
Volume 14, Issue 5 (12-2020)
Abstract
The use of piles, helical anchors and, in general, helical foundations has considerably increased in the last 30 years. The adoption of this technology in the international and domestic codes of each country, as well as in research and studies, and, finally, the publication of numerous books and papers in this area, and the existence of manufacturers’ products, committees, and contractors of this technology has contributed to its expansion and development. However, such methods have progressed at a very slow pace in many countries, especially in developing countries. This paper attempts to assess the global advancement of the helical foundations by reviewing 292 papers from 1990 to 2020 and comparing the related research findings. This will help clarify the issue and determine the scope of technological progress. On the other hand, collecting valuable papers in this area will make it easier for researchers to make further research. Subsequently, the characteristics of this technology are highlighted and the reasons for its lack of progress in the developing countries are addressed. For this purpose, a questionnaire is sent to researchers, developers, designers, and contractors of the geotechnical projects. The purpose of this questionnaire is to specify the type of existing projects, the soil type of project site, the degree of familiarity with the helical foundation technology, the reasons for not using this method and the solutions available to expand and develop this method. Finally, there are suggestions to develop this approach and the issues that need further research.
