Impact of Micropiles Installation on Liquefaction Potential of Saturated Silty Sand Using Numerical Method

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 pressure 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.