We started testing piles with analogue equipment  in 1980.  The technology is quite old now though with the aid of better computing power analysis of the results obtained for the test has been improved. We are probably the most experienced non-destructive pile testing company in the world even though we now concentrate more on existing structures rather than new piles. We basically stopped counting the number of piles tested years ago when we crossed the 500,000 tested mark! We have tested a large range of pile types with timber piles accounting for over 50,000 tested. We test other type of structures which can be found on our homepage Our main site is here. An older mirror site is here.

We found this pile after testing through the basement floor of a building! It was under taken due to of a partially collapsed building. Later on we with the aid of our associates we under took the repair and subsequent underpinning of the building

Integrity testing of foundations is a case of common sense plus the reliability of the testing equipment.  If you are unsure of the equipment then don't use it, if you do then you have to take the results as being correct.  Generally for a pile test analysis, if the toe can be identified then the subsequent analysis will  yield all the significant information on the pile condition, shape and capacity.  Major problems with similar PDA type testing is that the analysis is curtailed at a fixed arbitrary equivalent depth of the pile and not at the true depth.  This leads to mistakes in pile evaluation.

The photo is taken of a pile exposed after we under took the test. The test was made through the pile cap in a major high rise building we tested. The pile was constructed in the early sixties (1960's) when the use of bentonite became popular.  Its a typical defect of the time mainly due to the piling contractor  using a too short building tube. So when they extracted the tube, the surrounding soil intruded into the pile displacing the concrete.  (still happens a lot today). This pile had sheared and failed over a period of time. These type of defective piles fail in this manner, a cause for concern!

Some results are given

This is the actual model from the pile above,  basically after the seismic trace was collected the digital displacement time trace was converted into an mechanical admittance plot from which the model was derived.  What takes all day to do by hand can be done in seconds by the computer.  The modeling program has been up graded so that the below toe strata can be evaluated. A typical mechanical admittance plot is given below.

To present the results of the test in engineering terms, we have taken the guesswork  out of the analysis by presenting pile models and load plots.   The load plot is accurate to10% of a static load test with out the need to drop large weights, explosives or any other large dynamic forces. The equation of motion of the pile is affected by soil parameters, however they can only be considered in the elastic range. If the toe reflection is clearly identified then the captured return wave will contain all the physical information on the pile and pile/soil condition.  It is how good the analysis software is in extracting this data which determines the success of the test. Our software analysis package can model piles within and connected to structures, the modeling is useful where complex connections between piles and the structures exist. Applying some basic physics  we generate load test plots too!

Other parts of the analysis package results are shown .  The load test model is good up to the second tangent point from then on its really a mathematical good guess which for clays and cohesive soils is good but for non cohesive soils (sands) the equation of motion of the pile is difficult to define. Theoretically there are too many step functions in the solution equation to make it viable for a short time solution. It is sufficient to say after the second tangent point care has to be taken when using the results. The load model is probably our best selling product and maintains our lead in the pile testing business, Its winning factor is that the element length for normal pile testing is fixed whereas in real life it is variable. We take account of this when analysing results.  We have out performed all the major pile testing outfits when it comes to load test predictions and highlighted errors in static load testing tests.

Its our policy not to publish results less than five years old for privacy reasons. Our plots now include Z-modulus calculation and pile material E value.  Our present developments include the geophysical determination of below toe ground condition.