Performance of Driven Displacement Pile–Improved Ground in Controlled Blasting Field Tests

Abstract

Full-scale, controlled blasting field tests on driven displacement pile-improved ground were conducted to study the response of densified and reinforced ground to blast-induced excess pore pressures. In order to make appropriate comparisons to the baseline response of the native, unimproved ground, explosive charges sufficient to induce liquefaction were detonated in a control zone and the resulting postliquefaction settlements were measured. Excess pore pressures generated in the improved ground were observed to be significantly smaller than that in the unimproved ground, and resulted in settlements that were generally one-sixth to one-third of that measured in the unimproved ground. Piles tipped into a dense bearing layer settled significantly less than the surrounding soil and piles that were floated above the bearing layer. Importantly, measured excess pore pressures pointed to a change in soil response from contractive to dilative during blasting, indicating that the improved ground mobilized significant strength during blasting, similar to the response expected from cyclic mobility of dense soils. The energy of scaled ground motions developed from velocity measurements are used to relate the observed soil response to blasting to that expected from earthquake-induced ground motions. The paper concludes with a comparison of shear strains expected from shear strain compatibility (SSC) between the improved ground and the displacement piles to those implied by the measured pore pressures. The comparison indicated that some portions of the improved ground responded in an incompatible manner during the blast-induced ground motions and that the assumption of SSC may not be appropriate for design of some reinforcement-type ground improvements.

Blast-induced liquefaction in silty sands for full-scale testing of ground improvement methods: Insights from a multidisciplinary study

“…The PGV values provide an exponentially decreasing trend with distance, consistent with other field test evidences (e.g. Gianella and Stuedlein, 2017;Amoroso et al, 2017), recording ranges from 0.14 to 0.0007 m/s at 20 and 250 m distance from the blast centers, respectively.…”

“…In fact, previous J o u r n a l P r e -p r o o f experiences worldwide (e.g. Amoroso et al, 2017;Gianella and Stuedlein, 2017;Finno et al, 2016) provided evidence of a bowl shaped displacement surface following blasting. Furthermore, from the previous blast experiment carried out in a site of the Po River valley, it was observed that settlements in the circular blasting area were similar to liquefaction-induced vertical displacements predicted for a M w 7.5 earthquake in the same depth interval (Amoroso et al, 2017).…”

“…However, as the non-plastic fines content increased, the SC technique appeared to be more successful in combination with pre-installed wick drains (Adalier et al, 2003). Gianella and Stuedlein (2017) studied the behavior of sands and silty sands treated by TDP in South Carolina, proposing this technique as a suitable and potentially sustainable ground improvement alternative.…”

“…Previous experiences in the United States and New Zealand (e.g. Ashford et al, 2004;Wentz et al, 2015;Saftner et al, 2015;Gianella and Stuedlein, 2017) show that liquefaction can be induced and monitored in clean sands with controlled blasting. Some efforts have also recently focused on studying the behavior of siltier deposits during blast-liquefaction tests in Italy (Amoroso et al, 2017;Fontana et al, 2019;Passeri et al, 2018;Pesci et al, 2018).…”

Barriers in Implementing Sustainable Piling Construction Practices in Sri Lanka

“…According to Xu and Shi (2018), poor design and supervision of engineers have become a barrier to minimise material usage and related carbon footprint reduction. " Lack of piling construction expertise" has been highlighted as a key concern by Gianella and Stuedlein (2017). Moreover, lack of knowledge of ground improvement technologies and efficient pile construction techniques of the Engineer will hinder sustainability and costeffectiveness in piling construction.…”