Abstract:In response to the engineering challenges faced by shallow buried long-span cross-river tunnels crossing weak strata, such as poor rock stability and complex groundwater seepage paths, taking the Rongjiang Fourth Road Cross-river Tunnel in Ganzhou as the research object, the composite reinforcement mechanism of high-pressure jet growing pile (JGP) is systematically explored. Based on the FLAC3D three-dimensional elastoplastic numerical model, a constitutive relationship considering the interaction between slurry and soil is constructed, and the evolution law of the stress field - displacement field of the surrounding rock before and after reinforcement is compared and analyzed. The research results show that JGP enhances the cohesion of the reinforced zone by 3.8 times and increases the internal friction angle by 42.7% by forming a cement-soil skeleton structure, significantly improving the shear strength of the formation. The coupling analysis of on-site monitoring data and numerical simulation shows that the settlement of the arch crown has decreased from 110mm to 19mm, a decrease of 82.7%, which verifies the synergistic mechanism of the “bearing arch - waterproof layer”. The research results provide a quantitative theoretical basis for the reinforcement design of tunnels in water-rich and weak strata.
