Ground response and grout distribution by field soil grouting

Abstract

Generally, grout extent and ground deformation are of great concern in soil grouting practice. In this paper, the ground behaviour, injection mechanism and grout distribution relating to field grouting in soils are discussed. It is found that the mechanisms of injection comply with generally accepted groutability requirements based on particle size ratio, where suspension grouts fracture clayey soils and solution grout permeates sandy soils. Ground heaving is affected by the sealing effect of grouts in upper soil layers. This study shows ground heave increases with the depth of grouting. The final heave volume reaches about 22% of the total grout injected. Lateral ground expansion is influenced by the hydraulic fracturing of grouts. Hydraulic fractures, which are nearly vertically formed in soils, produce lateral movements of the ground. The final lateral expansion of the ground, within 1 m radial zone of the grout hole, is approximately 12% of the total grout injected. A three-dimensional grout distribution is postulated based on the mapped grout traces in soils. The observed vertical grout fractures, with apertures of less than 15 mm and lateral extents of 1~4 m, confirm that the site soil strata are normally consolidated.