RSUSSH 2020

IN20-142 Estimation of Long Term Pile Capacity from Results of Short Term Pile Load Tests.

Presenter: Kezang Wangmo
Rangsit University, Thailand

Abstract

          This paper presents results of a study on a method to estimate long term capacity of piles from results of short term pile load tests. In the study dynamic pile load tests at initial driving, 1 min, 10 min, 120 min, 1 day and 14 days were carried out at 27 sites distributed in the Bangkok and Metropolitan area. All the tested piles were pre-stressed concrete I shaped piles. Results of this study reveal that 1) increment of pile capacities with time is not a linear function of the logarithmic of time as proposed by Skov and Denver (1988). 2) Lower bound pile capacity at 14 days is 1.3 times that at 2 hours. 3) Pile capacity at 14 days (P14 days) can be estimated from pile capacities at 1 minute (P1 min) and 120 minutes (P120 min) by using the equation proposed in this report.

Keywords: Ple set-up; Driven Pile; Bangkok sub-soil; Clay

Citation format:

Wangmo, K., & Kuntiwattanakul, P.. (2020). Estimation of Long Term Pile Capacity from Results of Short Term Pile Load Tests.. Proceeding in RSU International Research Conference, May 1, 2020. Pathum Thani, Thailand.

QUESTIONS & ANSWERS

SAAD ALI USMANI (Visitor)

Thank you very much for your Nice presentation! Here I want to know how much initial dynamic pile load you considered for test at initial driving and what will happen if bound pile capacity exceeds the set limit?

Thammasak Rujirayanyong (Visitor)

can this equation be applied to other pile shapes? or any limitation?

Vannee Sooksatra (Visitor)

What is the limitation of this research?

 

Kezang Wangmo (Presenter)

Reply to @SAAD ALI USMANI (VISITOR)

 

We do not recommend using the results of initial dynamic pile load tests to estimate the pile load capacities since the scattering of the outcome will be very large as demonstrated in Table 5.1 of the paper. Instead, we recommend that a dynamic pile load test should be carried out at 120 minutes using a controlled test load of the required ultimate pile load divided by 1.3. This ensures, with 97% confident level, that the actual pile capacity will not be smaller than that required.

However, the results of this study also show that it is better to carry out pile tests twice, one at 1 minute and the other at 120 minutes and use the following equation to estimate the capacity at 14 days:

P14 days/P1 min= -17.02 (P120 min/P1 min)2+45.97(P120 min/P1 min)-28.13

This will give more accurate results with 99% confident level.

 

Kezang Wangmo (Presenter)

Reply to @THAMMASAK RUJIRAYANYONG (VISITOR) & @VANNEE SOOKSATRA (VISITOR)

 

The limitation of this research is that the results should be applied in Bangkok and its Metropolitan only. However, the idea of carrying pile load tests twice can be applied elsewhere.

Also, we believe that pile shapes will somewhat affect the increase of pile capacity with time since the increase of pile capacity depends on many factors such as the volume of soil displaced by pile driving, the surface area of the pile, etc.. Therefore, further studies should be carried out.