One of CMW’s specialist geotechnical services is the provision of dynamic pile testing services. CMW has a number of trained professionals experienced in undertaking dynamic pile testing using the SIMBAT and PDA techniques. The pile testing equipment is available through a Perth bases piling contractor or by external hire. We can also arrange for the provision of suitable piling hammers to undertake dynamic testing.
CMW can help ensure the proposed hammer will provide adequate energy, for the specified pile capacity, by conducting pile drivability assessment using GRLWEAP.
Our point of difference is provision of high quality dynamic pile testing capability that is cost effective, efficient and focused on the New Zealand market conditions.
CMW Geosciences (NZ) Ltd adopts a hands-on approach to help Clients solve challenges during construction and manage risk in, on and under the ground.
Dynamic Pile Testing
SIMBAT and PDA techniques are both well established dynamic pile testing systems that allow prediction of the static load settlement behaviour of bored, cast-in-place, driven pre-cast, steel tube (CHS) and H (US) piles. These systems are widely recognised as the benchmark for dynamic testing using the CASE method of wave analysis with validation features and CAPWAP analysis with the PDA technique and a synchronised digital theodolite with SIMBAT. The prime advantages of dynamic pile testing are the speed of testing and relatively low costs compared to static load testing. Up to 6 piles per day can be tested and preliminary results made available the same day. The rates of testing achieved are dependant on access, pile preparation and the nature of hammer use.
High strain dynamic pile testing methods are based on wave theory analysis of the propagation of stem waves in long elastic cylinders. Data analysis converts downward and upward (reflected) waves into forces and velocities and separates these to calculate the dynamic soil reaction.
The dynamic pile testing methodology is typically as follows:
- Install the test pile and mobilise a pile driving rig/hammer
- Install instrumentation which comprises one or two sets of strain gauges and accelerometers attached to the sides of the pile;
- An independent dumpy level or theodolite is normally used for the PDA method. With SIMBAT a survey target is installed and the digital theodolite set up to synchronise measured displacements with the strain gauges and accelerometers;
- Apply the dynamic load by dropping a mass onto the top of the pile and record strain, acceleration and displacement for each blow;
- Repeat this process for a number of blows of varying drop height to establish a stress-strain relationship;
- Acceleration and displacement signals are then integrated using the selected system software to establish corrected velocities;
- Further integration is then undertaken to convert signals into upward and downward forces to calculate the dynamic soil reaction for each blow;
- Dynamic soil reactions are then plotted with pile penetration. These plots are then corrected into static loads to develop a static load curve;
All test data collected is stored during the test and can be analysed immediately if required.
Full analyses are then completed and a detailed dynamic test pile report can typically be provided within 1 or 2 days of the testing.
CMW also provides services in Geotechnical Design, Site Investigation and Earthwork Monitoring and Testing