基于南昌艾溪湖共轨叠合隧道水下复杂非对称开挖深基坑项目，分析某典型断面两侧支护桩的变形差异，指出一定范围内调整支护桩设计长度对变形影响较小，可以优化设计桩长提高经济效益。简化模型进一步分析不同影响因素下的基坑支护结构力学响应规律，指出非对称开挖基坑支护结构应当使用非对称支护长度，并结合工程实践提出支护桩最优插入比概念。分析第2道支撑位置、不同支撑刚度、不同支护桩刚度和不同土质等因素对最优插入比的影响，提出基坑支护桩最优设计原则。结果指出： 非对称受荷侧的基坑支护桩可以通过调整受荷小一侧的设计长度实现优化设计； 同时，可以通过合理调整支护结构的设计刚度进行变形控制。所得结论现已应用到实际工程中，优化了支护桩的设计长度，取得了一定的经济效益。

Based on the project of underwater complex asymmetric excavation of deep foundation pit in Nanchang Aixihu overlapped tunnels, the deformation difference of supporting piles on both sides of a typical section is analyzed, and it is pointed out that adjusting the design length of supporting piles in a certain range has little effect on deformation, the pile length can be optimized to improve economic benefits. Then, based on the simplified model,  the mechanical response law of foundation pit supporting structure under different influence factors is analyzed, it is pointed out that asymmetric excavation foundation pit supporting structure should use asymmetric supporting length, and the concept of optimal insertion ratio of supporting pile is put forward combined with the engineering practice. Last, the effects of the second bracing position, different bracing stiffness, different supporting pile stiffness, and different soil on the optimal insertion ratio are analyzed, and the optimal design principle of foundation pit supporting pile is put forward. The result shows that the foundation supporting pile at the asymmetric loaded side can be optimized by adjusting the designed length at the side with smaller load, and the deformation can be properly controlled by adjusting the designed stiffness of the supporting structure. The conclusion has been applied in practical engineering, the design length of supporting pile has been optimized, and certain economic benefits have been obtained.