## 1 Introduction
The most significant difference is that the compressional loading at the head of a shaft in the top-down test causes compression in the concrete, causing outward radial strain (Poisson's effect), and affects the load transfer distribution within the shaft's depth. Bidirectional loading by the O-cell sacrificial jack also produces compression in the concrete pile; however, the load transfer distribution changes from the maximum in the location of the O-cell to almost zero at the head of the pile. Different patterns of load transfer distribution result in various distributions of side resistance within the pile's depth, depending on subsurface conditions, which in respect affect the measured total side resistance of a rock socket at the shaft head, using an Osterberg test [31; 32]. [PERSON] et al. [33] evaluated the available data that might allow direct comparisons between the Osterberg and conventional top-down loading tests on drilled shafts. Based on this evaluation, the differences in rock socket response between Osterberg and top-load tests are due to the modulus of the rock mass at very high slenderness ratios and interface friction angles. The study suggested that the equivalent top-load-settlement curve derived from an Osterberg load test under predicts side resistance for higher displacements. Conventional design methods for measuring the bearing capacity of drilled shafts are mainly developed for soil profiles in the absence of strong cemented layers, such as competent calcite. In previous research studies, the effect of side shear distribution on assessing the resistance capacity of the drilled shaft was investigated in homogenous soil [34; 35]. However, to the best of the authors' knowledge, few studies investigated the distribution of the side shear resistance of piles in soil containing competent cemented or strong rock layers. [36; 37]. The presence of such strong layers, affect the side shear capacity of a drilled shaft due to the interaction of these competent layers with the concrete pile. Moreover, full-scale tests, such as a conventional top-down test and an Osterberg cell test, are designed to measure the capacity of the drilled shaft in the absence of such cemented layers in the soil. Therefore, the presence of calcite competent layers in the soil profile enforces limitations on the traditional methods of drilled shaft test and design. These limitations can lead to unnecessarily conservative design, by underestimating the capacity of the drilled shafts. This study addresses this shortcoming in the design process of drilled shafts, and investigates the effect of competent calcite layers underlain by weak geomaterial on evaluating the response of axially loaded drilled shafts following full-scale Osterberg test results. The current load test approach is investigated for soil containing calcite. The soil profile in which the drilled shafts were installed is predominantly clay/clayey sand with highly cemented calcite layers. The load tests were performed in accordance with ASTM D-1143 \"Quick Load Test Procedures\" [38]. The effect of pile's elastic shortening on constructing equivalent top-down load-displacement curves based on the Osterberg test's measurement was reported by [PERSON] et al. [39]. In the present study, the elastic shortening is considered for a more accurate analysis of drilled shaft responses.