ADDITIONAL BEARING CAPACITY OF PILES DUE TO TIME DELAY OF INJECTION

The use of long piles to support construction loads has been recognized for thousands of years. In the last century, it has been introduced the use of pressure for embedding pile foundations that is named injected piles. In field implementations, if the design depth of the piles is long enough then additional piles are required to be connected. It needs time delay to connect between the earlier embedded pile to the additional one. The time delay can be also caused by other things such as equipment problems, unwilling bad weather etc. Based on the experience of pile injection records, due to the time delay, there is a temporary increase in pile bearing capacity, so it takes more effort to continue pile penetrations until the specified depth. In this study, the effects of erection time delays on piles are investigated. This study is conducted using experimental injected-pile models at the laboratory. The initial depth of earlier piles prior to further injection is set the relatively same, while the time delays are varied. The injection loads for penetration are recorded as well as the depth of penetration. The results of the experiments in terms of variation of time delays and additional penetration loads show that there are 'jump loads' at the initial last depth due to time delay until a certain period. It can be concluded that the time delay on the pile can increase the bearing capacity and must be limited to a certain time in case of pile connection work on site. The variation additional loads due to the time delays in a soil mass may be affected by soil parameters such as density and particle size of the soil.