Vertical Fiberglass Micropiles as Soil-Reinforcing Elements

Abstract

This article is dedicated to developing a ground improvement technique using vertically oriented reinforcement elements prefabricated utilizing fiberglass pultruded pipe and helical shape wideners at the bottom toe. Structures of the prefabricated helical micropiles varied by the length and cross-section area introduced into the soil massive as reinforcing bearing elements. The effect of the reinforcements geometry variation was investigated through a reinforcement factor (µ), based on which a calculation method for measuring settlement of reinforced soil has been previously developed Full-scale field plate load tests were performed before and after reinforcing the soil to investigate the changes in the soil stiffness after the reinforcement process. Comparative analysis between the reinforced and reference soft sandy soil indicates an average increase in the deformation properties of the fiber reinforced soils by 8%, 30%, 63% at the applied pressures of 100, 300, and 550 kPa, respectively. The influence of the fiber reinforced polymers (FRP) geometrical properties on the final composite settlement was determined. A comparative analysis of the calculated and the actual plate load tests results reveals that the previously proposed settlement calculation method is adequate for further development.

Settlement of Soil Reinforced with Vertical Fiberglass Micro-Piles

“…Although some discrepancies existed between the theoretical calculation and the experiment results, the obtained results represent an attempt to approximate the load–settlement curves according to the elastic behavior of the soil before and after the reinforcement by FRP micro-piles. Large-scale studies performed by the authors of this article have already been published previously [ 40 ]. However, further large-scale studies are still required to investigate the change patterns in the FRP-reinforced soil deformation modulus at different soil depths and applied loads.…”

“…The determination method for the micro-piles’ bearing capacity should be reviewed more carefully, considering the specific calculation details of the micro-piles as reinforcing elements. Hence, full-scale field test results [ 40 ] were used to verify the results of the proposed method. The site test included four soil samples reinforced by screw-type elements and one reference sample.…”

The results of strengthening the foundation with a bored pile with an enlarged pile base

“…To date, a large number of technologies for strengthening foundations, in particular strip foundations, are known in world practice [1][2][3][4][5][6][7][8][9][10][11]. However, not all of them can be used to strengthen the foundations of buildings and structures of historical development and cultural heritage, since, according to the requirements of regulatory documents, the development of additional settlements and tilt is unacceptable for such buildings [12][13][14][15][16]. When strengthening the foundations of buildings and structures of historical buildings and cultural heritage, the methods using "sparing" technologies are the most popular ones, since their use allows performing work without vibration and dynamic effects [17][18][19].…”