CFRP reinforced retaining walls with wall tie backs
CFRP can be an very effective means to reinforce, stabilize and repair damaged or deteriorated retaining walls. In order to effectively stop movement in a retaining wall, "restraint" has to be provided. For instance, if a wall is tipping and carbon fiber straps are added, the wall could still continue to tip but would do so as one reinforced sections. If tie backs or some other means of holding back the top of the wall are provided, then the CFRP will resist any movement between the tiebacks and the backfill restraining the base of the wall.
After the construction of the wall and the surounding parking lot, some cracking and movement was noticed. The solution was to stabilize and repair this wall as a combination of tiebacks and CFRP to provide flexural reinforcement between the tieback locations.
Initially this project was designed with tiebacks at the top of the wall. The existing field conditions did not allow this and the tiebacks had to be placed 2' down from the top of the 6' wall. Due to this field change, 3' sections of channel had to be added at each tieback loaction in order to transfer the restraint to the top of the wall. The carbon fiber was used to reinforce the wall between the vertical straps, similiar to a waler systems.
In instances where there is movement both vertically and horizontally, a grid pattern of carbon fiber can be used to provide stabilization for the wall and to resist any additional movement.