Test Pile – Seismic Strengthening Project
Testing of Injection Piles was completed in Christchurch, New Zealand in December 2011 at the old Bangalore Polo Club site at 136 Oxford Terrace with supervision, verification and sign-off completed by Opus.
The tests were designed to investigate the effectiveness of injection piles in the various soil types found in Christchurch. Controlled grouting was used when installing five test piles so that each pile had only a 3m grouted section in one soil type, as shown.
Four pull out tests and one compression test were completed with results showing that in all soil types a 3m grouted body had a higher bearing capacity than the steel reinforcing bar used. This shows that injection piles of this type exhibit a high degree of redundancy.
Pull-out testing of one injection pile was completed, under the supervision of Constructure Ltd, for a seismic strengthening project undertaken in Christchurch. This test was carried out by setting up a simple reaction frame as pictured below, and applying a tensile load with a hydraulic ram along the axis of the injection pile up to 90% of the yield value of the Ischebeck reinforcing steel – in this case equivalent to approximately 55 tonne.
A dial indicator fixed to an independent reference frame was used to record any movement of the pile while under load. Results showed that the pile withstood the applied load without moving, indicating a positive test result.