在考虑开挖引起土体回弹和土体强度特性、应力状态变化的基础上，提出了开挖条件下非均质地基中竖向受荷单桩非线性计算方法，并与已有试验结果对比，证明了简化方法的正确性，并对开挖前、后单桩的竖向承载特性的变化以及开挖后土体回弹对基桩受力和变形的影响进行研究分析。研究表明，常规试桩法和套管试桩法高估了基桩竖向极限承载力和桩顶刚度，采用常规试桩和套管试桩法得到的承载力作为设计值偏于不安全；开挖卸荷引起桩周土体回弹使得桩身出现拉力，开挖深度较大时桩身中、下部的配筋应充分考虑由于开挖引起的沿桩身的拉力，防止开挖过程中基桩被拉断；桩周土体的卸荷回弹将会引起桩顶刚度的明显降低。

In this study, a simplified nonlinear calculation method was developed to analyze the single pile in non-homogeneous soil under excavation, considering the unloading rebound of soil and changes of soil property caused by excavation. The calculated results show good agreement with testing results obtained by the present method, which indicates that the validity of this method is verified. Moreover, we studied the responses of the single pile after excavation under vertical load using the simplified method. It is found that the ultimate vertical bearing capacity and vertical stiffness of the pile loaded after excavation are overestimated by both the conventional loading test method and loading test with the sleeve method, which could lead to an unsafe design. In addition, excavation causes rebound of soils around the pile and then results in tension force in the pile. To avoid the pile be pulled apart, the reinforcing bars in the middle-lower part of the pile should be raised when the excavation depth is deep. The unloading rebound of soil around caused a great decrease in stiffness of the pile top.