Abstract The High Strain Dynamic Test (HSDT) offers an alternative approach to the conventional static load test for estimating the axial capacity of helical piles due to its faster implementation and potential cost savings. In this paper, a mathematical model developed by Clough & Penzien that simulates the force-time response at the top of a pile with uniform cross-section subjected to a hammer impact is evaluated for the HSDT setup. To verify the suitability of the model, the calculated force-time history from the mathematical model is compared with actual field data for driven and bored piles. The model is then used to explore the characteristics of hammer impact on helical piles with attention to estimating the impedance increase caused by the helices. Generally, helices offer additional end bearing resistance, thus increase the mechanical impedance of the pile. The obtained results demonstrate that it is necessary to account for the effect of helical plates in the analysis, especially for large diameter helical piles. Consequently, a method to approximate the increase in the pile impedance for a helical pile with single and double helices is developed using added soil mass model.

中文翻译：

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打入桩和螺旋桩高应变动态载荷试验产生的冲击力-时间响应分析模型

摘要 高应变动态试验 (HSDT) 提供了一种替代传统静载试验的方法，用于估计螺旋桩的轴向承载力，因为它实施速度更快，而且可能节省成本。在本文中，Clough & Penzien 开发的数学模型模拟了具有均匀横截面的桩顶在受到锤击冲击时的力-时间响应，用于评估 HSDT 设置。为了验证模型的适用性，将数学模型计算出的力-时间历程与打入桩和钻孔桩的实际现场数据进行比较。然后使用该模型探索锤击对螺旋桩的冲击特性，并注意估计由螺旋引起的阻抗增加。通常，螺旋提供额外的端部轴承阻力，从而增加桩的机械阻抗。所得结果表明，在分析中必须考虑螺旋板的影响，特别是对于大直径螺旋桩。因此，使用附加土体模型开发了一种近似单螺旋和双螺旋螺旋桩的桩阻抗增加的方法。