Induced liquefaction experiment in relatively dense, clay‐rich sand deposits

Abstract

[1] In this paper we report results from a controlled blast-induced liquefaction experiment at the field scale. The physical and mechanical properties of the materials at the subsurface are characterized by a suite of in situ and laboratory tests, including the Standard Penetration Test (SPT); downhole and cross-hole seismic velocity tests; density, porosity, and gradation tests; and direct shear tests. Since the blast experiment was performed above groundwater table, the subsurface was saturated by a sequence of controlled infiltration tests. A 50-kg TNT charge was detonated at a depth of 10 m, and seismic ground motions were recorded in a vertical geophone array positioned at a horizontal distance of 30 m from the blast borehole. Obtained liquefaction features include a water fountain that erupted from the blast borehole, prolonged bubbling of the water surface inside the infiltration trench (a process equivalent to ''sand boils'' typically observed at sites which have experienced liquefaction), lateral spreading, and surface settlement. We argue that in contrast to conventional predictions, liquefaction may be induced in relatively dense silty and clayey sands (shear wave velocity >300 m s À1 ; relative density = 63-89%) relatively rich in clays (fines content >30%) and that the driving mechanism should not necessarily be restricted to cyclic shear stress loading.

Large-scale infiltration experiments into unsaturated stratified loess sediments: Monitoring and modeling

“…Since liquefaction is feasible only under 100% pore-water saturation, it is critically important to achieve full saturation prior to inducing liquefaction. The quantitative description of water flow in the vadose zone and the saturation distribution profile, which are the topics of this paper, are the basis for the second stage, geomechanical study, the results of which are published elsewhere (Hatzor et al, 2007). Furthermore, it is important to note that due to the relatively large burying depth needed for the charge detonation, and due to the large distance needed for placing the monitoring equipment, the dimensions of the water infiltration experiments were actually huge.…”

Infiltration in layered loessial deposits: Revised numerical simulations and recharge assessment

“…Direct evaporation from the trench, in the order of 7.6 mm/d during July (see Section 4.1.2) could explain only a fraction of the difference (only 47 m 3 ). We hypothesize (partly based on a comparison of photos included in Gvirtzman et al (2008) and Hatzor et al (2009)) that the trench cover was less durable (hence less effective) during the second test, thus increasing the effective percolation area. Alternatively, there may have been technical issues with the water level or water use metering.…”

“…Soil moisture, bulk density, porosity, content of fines (<0.075 mm), and other parameters were measured every 2 m (Gvirtzman et al, 2008;Hatzor et al, 2009). Overall, the loessial sediment profile is stratified, with alternating horizons classified as silty sand, clayey sand, and low plasticity clay ('SM', 'SC', and 'CL', respectively) according to the Unified Soil Classification System (USCS).…”

“…The residual and saturated water contents (h r and h s , respectively) were set to representative values obtained in the field and lab (Hatzor et al, 2009) (Table 2). The pore connectivity and tortuosity factor l, which showed to be unimportant and/or insensitive in numerical experiments (e.g., Wang et al, 2003;Turkeltaub et al, 2015), was fixed at 0.5 for both soil units (Mualem, 1976).…”

Predicting potential of controlled blasting-induced liquefaction using neural networks and neuro -fuzzy system

“…Many studies are conducted in this context such as densifying sub-foundation soil of the Franklin Falls dam in New Hampshire [4], densifying loose soils in 40 m depth under Jebba dam in Nigeria [5], improving e ectiveness of soil reinforcement methods in order to decrease liquefaction in New Zealand [6], evaluating liquefaction potential in relatively dense clay-rich sand deposits [7], considering critical lines in lique ed soil such as pipelines and airport infrastructure [8]. In addition, many experimental studies have been conducted regarding blast-induced liquefaction of soil.…”