A Typical Design of Soil Nailing System for Stabilizing a Soil Slope: Case Study

Slope failures, is a common issue in construction industry, such that engineers have to avoid its risk on human lives and properties by an appropriate technical design of stabilizing methods. Soil nail is one of such stabilization methods. In this paper, soil-nailing system was studied in terms of inclination, spacing and length to determine the most appropriate values for effective stabilization of soil slope. To find the optimum soil nail system, different soil nail inclination, length and spacing were applied to a hypothetical homogenous soil slope (with inclination of 30o, 40o, 45o, 60o, 70o and 90o) and the Factor of Safety (FOS) was evaluated in each case. To validate the results, the optimum soil nail angle corresponding to a slope of 50o was applied to a case study slope, and the FOS of the case study slope was evaluated as well. The case study slope is located at Cadangan Menjalankan Kerja-Kerja Forensik Di Persiaran Endah, Seputeh Wilayah Persekutuan Kuala Lumpur. Results showed that the soil nails inclination; spacing and length have significant effect on the stability of the soil slope. For soil slope with steepness of 30o, 45o, 60o, 70o, and 90o; the best FOS was found with soil nail inclination (to the horizontal) of 50o, 40o, 20o, 15o, and 10o respectively. The effect of soil nails inclination on the stability of the soil-nailed walls is slight when the degree of inclination of the soil nails varies within 5o–20o to the horizontal. The stability of the slope decreases with the increase of spacing between soil nails. Soil nail length has significant effect on the stability of soil slope with deep-seated slip surface and less effect with shallow slip surface. The bond length behind the slip surface should be enough to allow the nail to use its allowable load.