Investigation of lateral behavior micropiled foundation under combined lateral and vertical loading

Micropiles are one of the most widely used components in civil engineering to strengthen foundations or improve the soil. These elements are also used in wind turbines. In addition to the vertical force resulting from the weight of the turbine, these tall structures are also affected by significant lateral force. This paper aims to investigate the behavior of a square micropiled foundation with the dimension of 20 cm under lateral loading. For this purpose, the reinforced foundation with 2, 4, and 8 micropiles with lengths of 40 and 60 cm in the sandy soil has been modeled experimentally and subjected to static lateral load. Also, the effect of vertical surcharge load on lateral bearing capacity has been investigated in different conditions. The results of the tests revealed that this type of reinforcement has improved the bearing capacity up to 6 times in some cases. Studying micropile collective behavior unveiled that, distant from collapse, micropile length minimally affected individual lateral capacity. In the extreme scenario (8 micropiles, 15% overload), this discrepancy was 30%. Varying micropile numbers near collapse produced two contrasting behaviors: amplification in one and reduction in another case. The determining factor in both instances was the micropile quantity, leading to a remarkable 200% role increase in the most extreme conditions.