Columbus, Ohio,
2008
ECO designed and directed the grouting operation to pre-condition the soil to facilitate tunnelling through a short “sand in-filled valley” in the rock formation. A multi-pass permeation grouting program prior to tunnelling was implemented to facilitate safe tunnelling through this mixed face and full face “soil” to prevent settlement of the road between the rock formations on both sides of the in-filled valley.
The pre-excavation grouting program consisted predominantly of permeation grouting and some permeation in conjunction with hydrofracturing. Five rows of vertical sleeve pipes were used to create a “Roman Arch” of grouted soil above the future tunnel trajectory
This program consisted of several grouting passes of multiple hole grouting using predominantly sodium silicate solution grout and some hydrofracturing with cement based suspension grouts.
On this project a permanent, inexpensive, sodium silicate grout was used for the first grouting pass. The tunnelling contractor, under the direction and hands-on supervision of ECO performed the grouting program.
During the grouting operation, each grout line was monitored and assess in real time using CAGESNS.