Abstract: The ground in Beijing area is mainly composed of waterrich weak soils containing fine sand, silty clay, and silty fine sand. The ground reinforcement cannot be applied to #5 and #6 connection galleries of BeijingShenyang highspeed railway shield tunnel because of buildings on the ground. Hence, to avoid the collapse damage of ground buildings induced by the strata settlement during prereinforcement process, the water and sand gushing due to poor reinforcement effect, and tunnel face collapse, the metro jet system(MJS) method is adopted to consolidate the strata with superhigh pressure horizontal jet grout piles, resulting in good reinforcement effect, which can improve the selfstability and confined water isolating effect of soils and reduce the influence of strata reinforcement and excavation on the settlement of ground buildings to the maximum extent. The results show that the maximum uplift of ground is 0.93 mm, the maximum settlement is -2.85 mm after excavation and lining completion, which meets relevant requirements and guarantees the building safety. The results indicate the prominent ground reinforcement effect of horizontal jet grouting pile by MJS method in waterrich clay, silty clay, and silty fine sand strata in urban areas, which can achieve good social and economical benefits.

Key words: metro jet system method, horizontal jet grouting pile, highspeed railway, shield tunnel, connection gallery, ground reinforcement