APPLICATION OF HORIZONTAL JET GROUTING PILES IN CONSTRUCTING A MINED TUNNEL IN WATER-RICH SAND LAYER

摘要

The research background of this paper is water-rich sand layer of Bao'er-Hexi section tunnel of Qingdao Metro Phase I Project,the paper focus on application of horizontal jet grouting pile pre-reinforcement technology in a mixed soilrock region featuring soft soil underlain by hard rock,and introduces difficult and key points in this project,and describes the process of optimizing horizontal jet grouting pile construction.To understand the reinforcement effect of jet grouting piles,we collected samples to carry out laboratory point load test and compressive strength test,and studied influences of jet grouting pile construction on ground surface settlement based on field monitoring data.The monitoring results demonstrate that 80％ of cumulative variations are within the control range,indicating that horizontal jet grouting piles have an obvious effect on controlling settlement.The research results provide a certain guiding significance for subsequent construction.