To explain the reinforcing effect and mechanism of horizontal drilling jet-grouting pegs on
surrounding rock around a tunnel, as an example, the reinforcing result of horizontal drilling jet-grouting
pegs for Shenzhen metro tunnel between Dajuyuan and Kexueguan stations was analyzed with the 3D
elastoplastic FEM (finite element method), and deformations induced by tunnel excavating with horizontal
drilling jet-grouting pegs or not were compared. In the analysis, jet-grouting pegs were simplified as solid
supportwith a thickness of 0.5 m. The numerical simulation result shows that the maximum excavation-
induced settlements of vault and ground surface are reduced to 50% or so and plastic area in surrounding
rock is reduced greatlywhen horizontal drilling jet-grouting pegs are used.