Closure to “Severe Damage of a Pile Group due to Slope Failure” by D. E. L. Ong, C. F. Leung, Y. K. Chow, and T. G. Ng

Abstract

The authors thank the discusser V. Diyaljee, for his interest in their research publication. To recap, this paper examines the prefailure and postfailure behavior of an instrumented cast-in-place concrete pile group comprising four 900-mm diameter piles subject to soil movements as a result of a slope failure that occurred during the unexpected early arrival of a rain storm prior to the year-end monsoon. Out of the four piles, two piles were instrumented. The front pile was instrumented with strain gauges only, while the rear pile was instrumented with both strain gauges and an in-pile inclinometer. The in-soil inclinometer that measured the free-field soil movement was installed about 1.5 m away from the pile group (Fig. 1). Because the soil slip was not anticipated in the pile design, only nominal 0.5% steel reinforcement was provided in the piles and this translates to an ultimate bending moment capacity of only 520 kN·m. In comparison, the ultimate bending moment capacity for a 1,075-mm diameter bored pile with 3% steel reinforcement used by Chandrasekaran et al. (1999) was about 3,000 kN·m, as additional bending moment due to soil movement had been anticipated.