A numerically investigate of the improvement of load carrying capacity of square footings utilizing micropiles

Abstract

This paper is aimed to address an actual case study on the use of micropile technology for improving the bearing capacity of an old building. The numerical simulation results show that the load-carrying capacity of square footing utilizing micropiles is notably increased. The improvement of the bearing capacity of the foundations depends on the strengthening methods, such as inclination angle ((), length (L), and distance of micropile from the edge of footings (S). Specifically, with the same length value of pile used, the bearing capacity reaches the largest magnitude at the S/B ratios of (0.5(0.75). The use of inclined piles yields a larger magnitude of bearing capacity than the vertical ones, these obtained results are contributed to the contribution of the “confining effects” of soil mass underneaths the footing as subjected to vertical loads. Additionally, if the soil mass below the footing has a high bearing capacity (firm to stiff clayey soils, medium to dense sandy soils…) , the design value of L/B ratio in the strengthening method should be in range of (2.0÷3.0), chosing beyond that optimal range is uneconomical since the improvement of bearing capacity is insignificant. In other words, the relationship between stress bulb in soil under the footing and the length of micropile should be taken into consideration to achieve a higher economic efficiency of the strengthening method.