Tension Pile Load Test 1

[mbilal89]

I have a requirement to conduct a tension pile load test for a test load of around 650tons. I want to know the most reliable way of tying the pile to the test beams for the pull. Recently I tried using prestressing cables for a test load of 515tons. The problem in using these is the elongation. The hydraulic jack a has limited stroke and the cables are pretty elastic. I am planning to make threads on the pile reinforcement and using bolts to make the pull. but I am not sure how to design the threads and the bolts. Can anyone help?

 

[Ingenuity]

But in my opinion, if that were the case, then there would have been some visible cracks on the ground surface. Some heaving of ground or cracks would indicate that the ground is being disturbed by something.

There are ground cracks, somewhat away from the test pile, but closer examination of the area around the pile zone may reveal evidence of ground movement.

and pressure won't increase if the stroke is exhausted.

Yes, it will. Internally, if the operator neglects to notice the jack stroke, the pump will continue to pressurize hydraulic fluid through the hoses, and the gauge will increase in pressure reading. It will not increase the load to the pile (as the stroke is maxed out) but the gauge reading will increase quickly. If the internal pressure exceed the max pressure (typically 10,000 psi, or 70 MPa), the system relief valve will release.

 

[ATSE]

LOk is correct. Your reference beams moved together with the pier; instead, they should have been at least 8m long.
Your test results, if accurate, are impressive indeed, but valid for skin friction stresses only. Your deflection data should be discarded; it has no value.
Also, your compression reaction supports are way too close to the pile. ASTM D1143 gives minimum distances (usually 3m min from pile to closes support for small diameter piles), which minimizes but does not eliminate the overlapping stress cones. For this test, your closest reaction should have been no closer than 4m.
You ran a direct shear test, not a pile test.

 

[mbilal89]

I understand that we were not actually going by the book (ASTM) when we talk about the procedures of testing. But I would like to point out that the code also suggests that the engineer may increase or decrease the 5D distance.

About the cracks, I doubt that the cracks you are pointing out to are due to ground disturbance. They may as well be, but from what I have experienced , the pattern of cracks is not like what is shown in the figure.

We had our limitations, because the pile was located on the median of a road, and we could not disturb the traffic on the road, so we couldn't use longer reference beams.

The information regarding the pressure on jack is new for me. I'll investigate that.

What do you mean when you say that we conducted a direct shear test?