Quality Control and Assurance for Improved Ground by Chemical Grouting

Abstract

This chapter describes how to determine the number of investigation points required to properly evaluate the unconfined compressive strength of ground improved by the chemical grouting method.The number of planar survey points for this ground is based on the government's administrative report and the manual for the permeation grouting method, and is, for example, based on three survey points for a soil volume of less than 5000 m3. However, this number of survey points is insufficient for this ground with spatial heterogeneity, and there is concern that the accuracy of statistical processing for evaluating variations in unconfined compressive strength and other parameters may be reduced.Therefore, we propose a new method that focuses on the chemical grouted rate (the ratio of the amount of chemical grouted to the design grouting rate) as the number of investigations required to evaluate this ground. We also present an example of setting the number of investigations according to the chemical injected rate using the actual ground surface at Airport A, which was improved by the permeation grouting method, one of the representative chemical grouting methods.