In order to lower the existing railway line through the City of Reno, several structures required underpinning of the foundations. In order to facilitate the underpinning process, Advanced Construction Techniques (ACT) was contracted to perform alluvium grouting.
The primary focus of the grouting operation was to permeate, stabilize and reduce the insitu hydraulic conductivity of the alluvium prior to conducting the underpinning work. Upon completion of the permeation grouting, excavations were performed without incident and the residual hydraulic conductivity was reduced to a value of 1x10-5 cm/sec resulting in a successful permeation grouting program.
The alluvium grouting process required drilling through the overburden and installation of Tube-a-Manchettes (TAM), or sleeve port grout pipes, in the alluvium. The sleeve-pipes were then injected with a combination of cement grouts and sodium silicate chemical grouts. The grouting operation was monitored with ACT’s IntelliGrout® computer monitoring system allowing adjustments to the permeation grouting operations to be made in real-time.
Grouting materials included: portland cement, bentonite, superplasticizer, and sodium silicate chemical grout. An extensive grout mix testing program was used to develop grout mix formulations for the project and extensive quality control testing was performed to ensure that mix properties were maintained throughout the project.