Assessment of Grouting Efficiency for Treatment of Underground Cavities

Ground subsidence incidents occurred in a residential suburb in an arid desert terrain due to sinkholes. Several investigation programs were conducted to understand the cause of the incidents attributed to the dissolution of the limestone bedrock and the subsequent ravelling of the overburden soil cover. A pilot area within the affected locale of the residential suburb in the state of Kuwait was selected for implementing treatment measures. The main purpose of the treatment measures was to fill the uppermost layer of the limestone bedrock in order to eliminate the risk of recurrence of ground subsidence. Cavity filling and permeation cement grouts were injected from the ground surface for filling the underground cavities and the fractured rocks. Results of the implemented grouting measures for treating underground voids and the GIN concept are presented in the paper. Reduction in the porosity of the bedrock layer due to the applied treatment measures was verified and percentage of treatment fill volume for the entire pilot area was estimated. An assessment method for the efficiency of the treatment measures coupled with the properties of grout materials, and lessons learned from the implemented treatment are also presented herein.