为了更加安全经济地进行土岩复合地层中基坑工程设计，针对上土下岩复合地层中吊脚桩基坑支护结构的受力及变形特性进行研究。采用二维数值分析方法，建立土岩复合地层条件下吊脚桩支护基坑开挖模型，分别分析基坑开挖过程中吊脚桩支护结构内力、变形的发展过程,以及土岩弹性模量比RE、吊脚桩嵌岩深度t、岩肩宽度b与桩体受力、变形之间的相关关系。结果表明： 1）随着基坑开挖深度逐渐增大，桩身侧移增大且桩身最大侧移发生位置逐渐下移，最大下移幅度为土层厚度的17.5%； 2）当基坑开挖至土岩交界面时，吊脚桩桩身内力达到最大值，下部岩层的开挖使得桩身最大负弯矩减小27.5%； 3）当岩层弹性模量介于600 MPa和4 800 MPa之间时，最优设计嵌岩深度为1.5 m，最优设计岩肩宽度为1.5~2.0 m。

In this paper, the mechanical and deformation characteristics of endsuspended piles of deep foundation pit in soilrock composite strata are studied, serving for safer and more economical design of deep foundation pit. Adopting An analytical model of deep foundation pit with suspendedpile retaining wall system in soilrock composite strata is established by twodimensional numerical simulation method. The main study content includes the development process of internal force and deformation of the retaining structure during the excavation and the relationship between the elastic modulus ratio RE, rocksocketed depth t, rockshoulder width b and the force, deformations of the piles. Some conclusions are drawn as follows: (1)The lateral displacement of the piles increases and the position of the maximum lateral displacement of the piles shifts downward as the excavation depth increases, and the maximum downward scope is 17.5% of the thickness of the soil layer. (2) When the foundation pit is excavated to the interface of soil and rock, the internal force of the piles reaches the peak, and the maximum negative bending moment of the piles is reduced by 27.5% due to the excavation of the lower rock layer. (3) When the elastic modulus of the rock layer is between 600 MPa and 4 800 MPa, the optimal design rocksocketed depth is 1.5 m, and the optimal design rock shoulder width is 1.5~2.0 m.