Cementation liquefaction remediation for existing buildings

Abstract

Many typical liquefaction remediation techniques are not appropriate for application under existing buildings and more novel techniques are required. This paper describes centrifuge tests investigating the performance of cementation as a liquefaction remediation method. Two soil profiles with the same superstructure were tested under earthquake shaking. The first profile consisted of a deep layer of loose, liquefiable sand. The second comprised a shallow layer of loose sand overlying dense sand. Centrifuge tests were carried out with a cemented zone underneath the structure, through the full depth of the liquefiable layers and also partial depth. The superstructure was modelled as a single-degree-offreedom system. It is found that a cemented zone through the full depth of a liquefiable layer results in considerable reduction of structural settlements. Increased magnitude and higher frequency accelerations are transmitted to the structure but, depending on the building characteristics, it is likely that improved overall seismic performance can be achieved. Improvements in structural settlements can also be obtained with partialdepth remediation, if the depth of the cemented zone is greater than the depth of liquefaction. This type of remediation seems to have little effect on the accelerations transmitted to the structure.

Geomembrane containment walls for liquefaction remediation

“…The actual properties of the sand layers in each centrifuge test are presented in Table 1. The actual instrument positions are given by Mitrani (2006).…”

“…The properties adopted for this sand are shown in Table 2 and the particle size distribution curve is shown in Figure 3. Derivation of these soil properties is given in Mitrani (2006), with the exception of the peak friction angle, which was determined by triaxial tests on a similar grade of Hostun sand, Hostun RF (Gay et al, 2003). The dense layers of sand were produced by pouring the sand with a very low flow rate and a large drop height.…”

“…In the model for WA3, the dense layer was poured by hand then additionally compacted with four passes of a Proctor Compactor on a thin metal plate. For more details, see Mitrani (2006). As most of the sand pouring was done by hand, it was difficult to avoid small variations in layer depth and relative density.…”

Field testing of permeation grouting using microfine cement

“…The lowering of the groundwater table and the construction of lattice-shaped improved soil walls by means of jet grouting are thought to provide most plausible solutions according to geotechnical engineers and researchers in Japan, provided a sufficient number of owners of private houses together agree to implement the changes. In looking at some of the recent research efforts, the effects of deep mixing configurations on the seismic response of an improved site have been an important issue when considering the relevance of using ground improvement technology for soil liquefaction mitigations (Mitrani and Madabhushi, 2010;Porbaha, 2008a, 2008b;and others). Permeation grouting using sodium silicate solutions has also been widely applied for its mitigation effects on individual structures (e.g.…”

Discussion: Cementation liquefaction remediation for existing buildings

“…The authors present experimental results (Mitrani and Madabhushi, 2010) of great interest and importance for geotechnical earthquake engineers. Cementation techniques applied to loose and saturated soils under existing structures undergoing cyclic movement are assessed.…”