Investigation of the effect of micropile driving angle on bearing capacity of problematic soils

Population growth and development of building industry in the recent years without considering geological and geotechnical aspects, have caused numerous engineering problems such as collapse or formation of cracks, uneven settlement in the building, and liquefaction of the soil during earthquakes. One of the solutions in facing problematic soils such as loose soils with low bearing capacities and higher settlement potential is the use of micropiles. According to construction method of the micropiles, different driving angles can be used relative to the vertical. The purpose of the present article is to investigate the effect of different angles of the micropile construction on the behavior of the micropiles in problematic soils to find an optimum design. The investigation method consists of modeling micropiles with 10, 20, and 30 degrees with respect to the vertical and presenting the ground settlement variations along with internal force profile of the micropiles. The results show that with increasing the angle of the micropiles, axial settlement is reduced, and also the internal moments and forces of the micropiles increases. This shows that there is no optimum angle for micropile construction, and the most optimal design should be made according to the propose of the design based on either controlling the settlement or structural design of the pile. According to the soil properties of the project and due to importance of limiting the maximum settlement of the structure foundation to 2.5 centimeters, an angle of 20 to 30 degrees and around 25 degrees is recommended.