Liquefaction Potential of Saturated Sand Reinforced by Cement-Grouted Micropiles: An Evolutionary Approach Based on Shaking Table Tests

Abstract

Cement-grouted injections are increasingly employed as a countermeasure material against liquefaction in active seismic areas; however, there is no methodology to thoroughly and directly evaluate the liquefaction potential of saturated sand materials reinforced by the cement grout-injected micropiles. To this end, first, a series of 1 g shaking table model tests are conducted. Time histories of pore water pressures, excess pore water pressure ratios (ru), and the number of required cycles (Npeak) to liquefy the soil are obtained and modified lower and upper boundaries are suggested for the potential of liquefaction of both pure and grout-reinforced sand. Next, adopting genetic programming and the least square method in the framework of the evolutionary polynomial regression technique, high-accuracy predictive equations are developed for the estimation of rumax. Based on the results of a three-dimensional, graphical, multiple-variable parametric (MVP) analysis, and introducing the concept of the critical, boundary inclination angle, the inclination of micropiles is shown to be more effective in view of liquefaction resistivity for loose sands. Due to a lower critical boundary inclination angle, the applicability range for inclining micropiles is narrower for the medium-dense sands. MVP analyses show that the effects of a decreasing spacing ratio on decreasing rumax are amplified while micropiles are inclined.

Performance of Pile Group in Soils Prone to Liquefaction Affected by Far and Near Earthquakes

“…nDMaterial PressureDependMultiYield $tag $nd $rho $refShearModul $refBulkModul $frictionAng $peakShearStra $refPress $pressDependCoe $PTAng $contrac $dilat1 $dilat2 $liquefac1 $liquefac2 $liquefac3 where in: $tag number of material used $nd the number of dimensions that can be 2 for plane strain and 3 for three-dimensional analysis. $rho is the saturated mass density of the substance $refShearModul soil shear module $refBulkModul is the bulk modulus of the soil obtained from equation 25-4 $frictionAng internal soil friction angle $peakShearStra octahedral shear strain where the maximum shear strength occurred and from the relation ( 16) (17) $refPress Confinement average pressure where , and are defined .…”

“…In this research, the UBCSAND constitutive model was used to investigate the behavior of liquefacted sand under dynamic loading. UBCSAND is a twodimensional effective stress plasticity model that is used in advanced stress-deformation analysis of geotechnical structures (10)(11)(12)(13)(14)(15)(16)(17)(18)(19). This model was developed to investigate the behavior of sandy soils with liquefaction potential under dynamic loading (e.g.…”

Anisotropy in the Liquefaction Resistance of Fibre Reinforced Sand

“…Once fibres are added to loose sand, a strain-softening response is prevented from developing, and the static liquefaction remains absent [30,31]. Shaking table tests provide a means to improve the understanding of earthquake loading-induced liquefaction [32,33]. Maheshwari et al [34] investigated the liquefaction resistance of Solani sand reinforced using different types of fibres through shaking table tests.…”