The present study aimed to establish a simple and rapid procedure to calculate the installation torque of multi-helix piles, widely used as guy-wire anchors and foundations for transmission line towers in Brazil, based on the standard penetration test (SPT) results. For this purpose, an equation was developed considering a theoretical relationship between the pile uplift capacity and installation torque and soil disturbance effect on the torque resisted by the pile shaft and helices during installation. The proposed expression was fitted to the data obtained from 571 six-helix piles installed in clayey sand sites (457 piles were used as the training dataset and 114 were used as the validation dataset). Among other findings, this study indicated that (i) the proposed equation results in a measured-to-predicted ratio of 1.00 with a coefficient of variation (COV) of 10.2% for the training dataset and of 1.01 with a COV of 11% for the validation dataset; (ii) the accuracy of the method presented was improved using a correction factor based on the average N-value of the soil around the first three tapered helices; (iii) although slightly conservative, the torque obtained by the current method was also consistent with the prediction of the installation torque of additional four-helix pile data; and (iv) a parametric analysis indicates that the installation torque depends strongly on the area of the helices. Finally, the method described in this note can successfully predict the installation torque of multi-helix piles in conditions similar to those of the database, which are typical in Brazil.

本研究旨在建立一个简单快速的程序来计算多螺旋桩的安装扭矩，多螺旋桩广泛用作巴西输电线路塔的拉线锚和基础，基于标准穿透试验 (SPT) 结果。为此，考虑了桩的抗拔能力和安装扭矩之间的理论关系以及安装过程中土壤扰动对桩轴和螺旋所抵抗扭矩的影响，开发了一个方程。所提出的表达式被拟合到从安装在粘土砂场中的 571 个六螺旋桩获得的数据（457 个桩用作训练数据集，114 个用作验证数据集）。在其他发现中，该研究表明 (i) 提议的方程导致测量与预测的比率为 1。00，训练数据集的变异系数 (COV) 为 10.2%，验证数据集的变异系数 (COV) 为 1.01，变异系数 (COV) 为 11%；(ii) 使用基于平均值的校正因子提高了所提出方法的准确性N -前三个锥形螺旋周围土壤的值；(iii) 虽然略有保守，但当前方法获得的扭矩也与附加四螺旋桩数据的安装扭矩预测一致；(iv) 参数分析表明安装扭矩很大程度上取决于螺旋的面积。最后，本说明中描述的方法可以成功预测多螺旋桩在与数据库相似的条件下的安装扭矩，这在巴西是典型的。