In this study, the side capacity of drilled shaft foundations is estimated from partially-mobilized load–displacement field data using a new method in the extrapolation of load–displacement response. A dataset of 138 bi-directional load tests is used to evaluate the degree of mobilization of unit side resistance. A total of 612 unit side-resistance curves obtained from measured strain gauge recordings are utilized in this study. The proposed extrapolation approach is based on a new technique, the Double Tangent method, characterizing the extent of mobilization for each unit side-resistance curve. Roughly, 12% of the dataset exhibits a fully-mobilized load–displacement response, with the remainder exhibiting varying degrees of a partially-mobilized response. Fully-mobilized records are further characterized using the Double Tangent method over different ranges of mobilization, resulting in four regression models based on predominant soil types. Each model is assessed statistically, and a global regression model is found suitable to predict maximum unit side resistance. The global model is further validated using two independent load test datasets, comparing measured values of unit side resistance against predicted values. The model is then used to predict maximum unit side resistance for all partially-mobilized data within the dataset, and the results are compared to two extrapolation techniques currently used in practice. The corresponding resistance-displacement response is extrapolated using a proposed asymptotic curve-fitting function for side resistance, and an example extrapolation is illustrated to showcase how the proposed method can be used in engineering practice.

在这项研究中，使用一种外推载荷-位移响应的新方法，从部分移动的载荷-位移场数据估计钻孔轴基础的侧向承载力。使用 138 个双向负载测试的数据集来评估单元侧阻力的动员程度。本研究使用了从测量的应变计记录中获得的总共 612 条单位侧电阻曲线。所提出的外推方法基于一种新技术，即双切线方法，用于表征每个单位侧阻力曲线的动员程度。大约 12% 的数据集表现出完全动员的载荷-位移响应，其余的则表现出不同程度的部分动员响应。使用双切线方法在不同的动员范围内进一步表征完全动员的记录，从而产生基于主要土壤类型的四个回归模型。对每个模型进行统计评估，并找到适合预测最大单元侧阻力的全局回归模型。使用两个独立的负载测试数据集进一步验证全局模型，将单元侧电阻的测量值与预测值进行比较。然后，该模型用于预测数据集中所有部分移动数据的最大单位侧阻力，并将结果与​​目前在实践中使用的两种外推技术进行比较。使用建议的侧向阻力渐近曲线拟合函数推断相应的阻力 - 位移响应，