Dear Li,
Attached is our estimate pile length based on our standard practice. Most of the piles will be embedded in hard clay or semiconsolidated mudstone/claystone which is quite difficult to estimate its skin resistance and end bearing correctly. The pile length given in the Table is generally conservative and it is expected that the actual pile capacity based on pile load test will generally be higher than the required capacity. It is strongly recommend to perform only a few number of pile load tests first to gain better understanding on its skin resistance and end bearing. This will allow the designer to adjust their pile design which may result in a cost saving of the project. Then, another set of pile load tests will be carry out to confirm their revised design. But I am not sure if your current construction schedule will allow you to carry out pile load tests in two different stages.
By the way, who is really your designer who is responsible for pile length design. Also, in the excel file that you sent me earlier, the pile lengths vary between 13and 26m. If you have their calculation, we would like to review and give you some comments.
For the pile stiffness, I am not really sure what you want us to help you because the pile stiffness can directly be estimated from the pile cross sectional drawings you gave me earlier. Your clarification is appreciated.
Regards,
Teerawut