Induced-Partial Saturation for Liquefaction Mitigation: Experimental Investigation

Abstract

The technical feasibility of a new liquefaction mitigation technique is investigated by introducing small amounts of gas/air into liquefaction-susceptible soils. To explore this potential beneficial effect, partially saturated sand specimens were prepared and tested under cyclic shear strain controlled tests. A special flexible liquefaction box was designed and manufactured that allowed preparation and testing of large loose sand specimens under applied simple shear. Partial saturation was induced in various specimens by electrolysis and alternatively by drainage-recharge of the pore water. Using a shaking table, cyclic shear strain controlled tests were performed on fully and partially saturated loose sand specimens to determine the effect of partial saturation on the generation of excess pore water pressure. In addition, the use of cross-well radar in detecting partial saturation was explored. Finally, a setup of a deep sand column was prepared and the long-term sustainability of air entrapped in the voids of the sand was investigated. The results show that partial saturation can be achieved by gas generation using electrolysis or by drainage-recharge of the pore water without influencing the void ratio of the specimen. The results from cyclic tests demonstrate that a small reduction in the degree of saturation can prevent the occurrence of initial liquefaction. In all of the partially saturated specimens tested, the maximum excess pore pressure ratios ranged between 0.43 and 0.72. Also, the cross-well radar technique was able to detect changes in the degree of saturation when gases were generated in the specimen. Finally, monitoring the degree of partial saturation in a 151 cm long sand column led to the observation that after 442 days, the original degree of saturation of 82.9% increased only to 83.9%, indicating little tendency of diffusion of the entrapped air out of the specimen. The research reported in this paper demonstrated that induced-partial saturation in sands can prevent liquefaction, and the technique holds promise for use as a liquefaction mitigation measure.

Experiments and Predictions of Soil Desaturation by Air-Injection Technique and the Implications Mediated by Multiphase Flow Simulation

“…As experimental evidences of lowering liquefaction susceptibility induced by desaturation, Okamura and Teraoka (2005), Yegian et al (2007) and Takemura et al (2009) carried out 1g and centrifuge shaking table tests and showed that desaturation of foundation soil has signiˆcant eŠects to reduce generation of excess pore pressure and settlement of structures. Yoshimi et al (1989) have conducted cyclic torsional shear tests and concluded that a soil specimen shows threefold liquefaction resistance ratio as the degree of saturation decreases from fully-saturated to 70z.…”

Development of dynamic impact cone for assessing induced partial saturation (IPS) as liquefaction mitigation technique

“…Small scale laboratory testing has shown the benefit of IPS as described in Yegian et al [1] and EsellerBayat et al [2], [3]. Most recently the benefit of IPS treatment was also observed and proven in large scale laminar box tests in NEES University of Buffalo facilities, these results were analyzed and presented by Nababan [4].…”

“…Researches on finding effective and cost effective liquefaction mitigation techniques are still undergoing in many part of the world. One promising new mitigation technique which is innovative, practical, and cost effective was proposed by Yegian et al [1] …”

“…Current liquefaction mitigation techniques used in practice are expensive. A new innovative mitigation technique which is cost effective was proposed by Yegian et al [1] called "Induced Partial Saturation" (IPS). This method involves in generating gas bubbles within the pores of fully-saturated sand and transformed it to partially-saturated sand.…”

Prevention of Liquefaction of Saturated Sand Using Biogas Produced by Pseudomonas stutzeri

“…Several methods about generating gas in pores of sands have been proposed. These including air injection (Okamura et al, 2006), water electrolysis (Yegian et al, 2007), drainage-recharge technique (Yegian et al, 2007), biogas . Biogas mainly is nitrogen gas produced by the microbial denitrification process.…”