Statistical Assessment of Bearing Capacity of Cast-In-Situ Bored Piles Using Direct CPT and SPT Methods: A Case Study

Abstract

Determining bearing capacity of piles has always been challenging for geotechnical engineers. Various methods are recognized for determining pile capacity, like analytical approaches based on laboratory testing and pile load tests which are time-consuming and expensive. Hence, a series of empirical approaches were developed to predict the pile capacity from in-situ tests, such as cone penetration test (CPT) and standard penetration test (SPT). This paper investigates the pile capacity directly based on SPT and CPT data because it is simple, fast, economical, and similar to a pile. Thus, the prediction capability of the four CPT and the two SPT methods is compared with direct field pile loading tests performed on five bored piles implemented in the Shahid Rajaee Port project. Six statistical criteria were selected for evaluating the prediction methods. The performance of different approaches was compared considering the sum of the Rank Index (RI) from the statistical indicators. According to the statistical studies, the Schmertmann and the Meyerhof methods indicated the best agreement with field test results among empirical CPT and SPT methods, respectively. The proposed case study investigation can help engineers benefit from in-situ SPT and CPT tests as a simple method to improve accuracy in bored pile design.