为解决基坑内支撑调节长度与支护结构位移、轴力安全控制问题，基于平面应变问题建立基坑单道和多道内支撑动态调节理论计算模型，推导得出内支撑调节引起的内支撑轴力和地下连续墙位移变化的计算方法，提出内支撑动态调节范围的确定方法，并通过工程实例验证理论方法的正确性。研究发现： 1）内支撑调节需要在一个安全合理的范围内进行伸缩调节； 2）文中的理论方法可用于确定内支撑动态调节的安全合理范围； 3）当求得的最小调节量大于调节上限值时，即使内支撑动态调节也无法满足基坑安全控制的要求，说明基坑支护方案不合理，需要重新设计。

To balance the conflict of displacement and axial force of the support system and adjust the length of the internal support, a theoretical calculation model is developed for the dynamic adjustment of single and multiple internal supports of foundation pits based on the plane strain problem. A method for calculating the axial force of the internal support and the displacement of the diaphragm wall caused by the adjustment of the internal support is derived. In addition, a method for determining the dynamic adjustment range of the internal support is proposed. The theoretical method is validated through engineering examples. The findings reveal that the internal support requires adjustment within a reasonable range and the theoretical method presented in this study can be used to determine the appropriate range of dynamic adjustment of the internal support. However, when the calculated minimum adjustment value exceeds the upper limit value, i.e., when the dynamic adjustment of internal support fails to meet the safety control requirements, the foundation pit support scheme is unreasonable and must be redesigned.