Consultation document on suitability tests for stress absorbing layers behind integral bridge abutments

In general joint-free integral bridges are considered more durable and cheaper in whole life cost than conventional bridges with joints and bearings. However seasonal cyclic thermal movements of the deck cause interactions between the bridge abutments and the retained soil such that lateral earth pressures behind the abutments are likely to progressively increase with time. One method of avoiding the development of these high lateral pressures is to use a low stiffness but compressible elastic backfill as a stress absorbing layer behind the abutment. The performance requirements for stress absorbing layers have been previously identified and this report provides an initial proposal of methods of testing to assess if these requirements are satisfied. (A)