Comparison between estimated and measured ultimate bearing capacity of bored piles

The ultimate bearing capacity of piles is estimated theoretically through equations depending on soil properties and pile dimensions. it can be also estimated through empirical correlations with field tests such as standard penetration test and cone penetration test. the dimensions of piles sometime obstructed the applications of these equations especially for pile diameter more than 60 cm. due to the non-homogeneity of soil,the estimated bearing capacity has some uncertainties,so all the international codes stated that it should be confirmed by pile load tests. these tests are generally carried out up to certain loads equal to 1.5 or 2.0 times the allowable loads. although carrying out the pile load test up to the ultimate load can be costly and time consuming,it is considered a reference for evaluating the theoretical and empirical methods. several instrumented pile load tests were published up to the ultimate loads. these tests included wide range of piles dimensions,different types of soil conditions besides end bearing and skin friction measurements. in the light of these measurements,this paper presents comprehensive comparisons between the measured and estimated bearing capacities of piles. the estimated bearing capacities depended on the methods mentioned in the egyptian and the canadian codes. moreover,comparisons were also performed between the measured and estimated settlements at the ultimate loads according to the mentioned codes.