Effect of Injection Rate on Clay-Grout Behavior for Compensation Grouting

Discussion of “Forms and sand transport in shallow hydraulic fractures in residual soil”Appears in Canadian Geotechnical Journal, 43: 1061–1073.

“…It was observed by the authors in their field experiments that the fractures were shaped like slightly asymmetric saucers that were roughly flat-lying in their centers and slightly curve upwards. In fact, similar fracture pattern was observed in laboratory experiments on hydraulic fracturing conducted by injecting cement bentonite and epoxy into clay specimens with overconsolidation ratio of 5 under similar free surface boundary condition (Chin 1996;Au 2001;Au et al 2003Au et al , 2005Soga et al 2003). It has also been demonstrated experimentally in the laboratory that hydraulic fracture may be initiated by injecting a small volume of fluid into highly overconsolidated clay.…”

“…The result is consistent with the theoretical ultimate cavity expansion pressure in soil (Au et al 2006). However, the magnitude of fracturing pressure is dependent on injection rate and overconsolidation ratio of the soil (Mori and Tamura 1987;Au 2001;Soga et al 2003), as shown in Fig. D1, where P f is the fracturing pressure and 0 v is the effective overburden pressure.…”

Equipamento para Ensaios de Expansão de Membrana

“…Neste estudo, as expansões buscam representar o comportamento do geoenrijecimento. Esta investigação de laboratório é baseada nos estudos sobre Compensation Grouting (Au, 2001;Au et al, 2003;Soga et al, 2003;Soga et al, 2004;Komiya et al, 2001), técnica utilizada na compensação de recalques causados durante escavações subterrâneas e também nos estudos sobre Compaction Grouting (Wang et al, 2010;Wang et al, 2013) técnica de melhoramento de solos que busca densificar o solo por meio da expansão de bulbos de argamassa. Estes pesquisadores realizaram vários ensaios em aparatos modificados (consolidômetro e câmara triaxial), os quais possuíam uma agulha no centro para permitir a expansão do material no interior da amostra.…”