Restoration of Tilted Buildings via Micropile Underpinning: A Case Study of a Multistory Building Supported by a Raft Foundation

Abstract

This paper presents a real case study of a micropiling process that was developed to stop the continuous tilting of a 9-story residential building in Dakahlia, Egypt. Shortly after the construction of the building, the surface raft foundation exhibited severe settlement problems. In order to carry out a geotechnical investigation, boreholes were drilled around the constructed building. It was discovered that in addition to a thick, soft clay layer in the soil profile, there was also a crucial eccentricity between the centroid of the total building loads and the centroid of the raft. The issue needed to be addressed immediately, and a micropiling system was proposed to satisfy the geotechnical and structural conditions associated with the case history. In addition to describing the field measurements, detailed methodology, and micropile installation process, this paper also presents three different design approaches for determining the number and location of the micropiles. Although the underpinning process itself initially induced some settlement, micropiling the raft proved to be an efficient solution to stop the continuous tilting of the building. A micropile load test confirmed the advantageous effect of the grouting technique used for Type B micropiles, where the grout is injected under high pressure.

Important Guidelines On The Finite Element Modelling Of Micropiles

“…Micropile diameter Steel reinforcement Reinforcement ratio Farouk [7] 0.15 m 3 bars of 32 mm in diameter 13.7% Kyung et al [10] 0.165 m 1 bars of 65 mm in diameter 15.5% Elsawwaf et al [15] 0.20 m 1 Steel tube with an inner/outer diameter of 76/89 mm 5.4%…”

Assessment of Enhanced Load-Bearing Capacity of Expanded Steel Pipe Piles Considering Optimal Configuration

“…Moreover, micropiles have been used to reinforce existing foundations, supporting additional loads on existing buildings [15,16]. Sometimes, micropiles were employed to mitigate the tilt of raft foundations beneath existing structures [17].…”

Research on the Characteristics of Jacks Used to Rectify Tilted Buildings

“…A significant number of tilted buildings are stabilized by reinforcing the foundations with various types of piles, such as pressed-in micro piles [27], steel piles [28], and reinforced concrete piles [29], or through soil reinforcement [8]. If individual structural elements become deflected, they are then stabilized in a new position [30].…”