Grouting in rock cavern - a case study

Abstract

It is essential for the use of grouting in a rock cavern to provide stability of the cavern and to reduce the water ingress through rock joints. However, it is difficult to determine the amount of grout needed as too much grout may lead to other issues while too little grout may render the whole grouting process useless. In this report, we study two tunnels in Singapore’s Jurong Rock Cavern (JRC), namely OT0-1C and OT1-2, in order to determine the parameters that may potentially give a reasonable estimate for the amount grout needed. At the first step, based on past studies and existing relationship, we determined the parameters to be used in this study to be water ingress rate, water ingress pressure, drill hole depth, w/c ratio of grout, rock quality designation, Q-value, rock mass rating, cohesion, friction angle, deformation modulus, tensile strength and hydraulic conductivity. We then make use of the increasingly popular Artificial Neural Network (ANN) to establish a model based on the data mined from OT1-2, in order to predict the volume of grout needed for OT0-1C. Finally, we compare the results with the actual volume to determine the model’s accuracy and usability.