Experimental investigation of helical soil nail group behavior under torque installation and monotonic pullout loading

• DOI: 10.1007/s12517-021-07840-7
• Publication Date: 2021-07-14T18:09:50Z
• Authors: Pankaj Sharma; Saurabh Rawat; Ashok Kumar Gupta
• Keywords: 0211 other engineering and technologies; 02 engineering and technology

In field practices, helical soil nails are installed in groups with staggered or uniform spacing. However, among the few prevalent literature on helical soil nails, studies regarding the group effect of helical soil nails are rare. Thus, to evaluate and better comprehend the behavior of helical soil nails in the group, an experimental investigation is conducted on a single and group of helical soil nails in the sand. The installation and pullout characteristics are evaluated under varying surcharge pressures and inclinations of 0°, 5°, 10°, 15°, 20°, 25°, and 30° with horizontal. During installation, the soil disturbances are also examined in terms of the installation disturbance factor (IDF). The group behavior is studied under two different configurations of staggered and uniform spacing. The earth pressures, torsional strains, and axial strains developed are also investigated. The test results suggest an optimized inclination range between 10° and 25° with horizontal showing low average IDF of 0.76, high torsional and axial strains. Helical soil nail group with staggered spacing revealed higher group efficiency, pullout resistance, and smaller installation torque in comparison to the group with uniform spacing. Also for uniform spacing, negative earth pressures along with large torsional strains and axial strains are observed.