关键词: MJS工法桩;深厚软基;高铁桥梁;喷浆压力;滨海地区;

Abstract: In order to explore the influence of large area construction of piles by MJS(Metro Jet System) construction method(MJS pile for short) on the surrounding environment and to evaluate its safety, based on the first example of strengthening railway-related soft foundation by MJS piles in the coastal area of Fujian Province, the construction process was discussed through pile test and the influence law of construction method piles on the surrounding environment was comprehensively analyzed.The results showed that the soil disturbance caused by single pile construction was small, while the cumulative effect caused by multi-pile construction can not be ignored.The horizontal deformation of the soil along the depth generally presented a trend of "up big and down small",and the influenced depth range of the soil at different distances from the pile side was obtained.Based on this range, the soil around the pile was divided into the main influenced area, the medium influenced area and the mild influenced area.The change rate of soil pore pressure increased first and then decreased along the depth, indicating that the deeper soft soil with less structural disturbance was more sensitive to the shotcrete pressure.During the construction of MJS piles, the deformation of piers and abutments adjacent to the high-speed railway bridge was basically in an irregular oscillation state.After the completion of the test pile construction, with the reshaping of the soft soil structure, the deformation of piers and abutments tended to be stable, and the absolute value and differential settlement were far less than the specified value, which would not endanger the stability of pier and abutment structure and the safety of high-speed railway operation.

Key words: MJS pile; deep soft foundation; high speed railway bridge; shotcreting pressure; coastal area;