MJS工法具有全方位、高精度、集中排泥等优点，在复杂多变的地质和盾构穿越既有车站等不利施工条件下有着较强的适应性。为研究水平MJS成桩对周围粉砂地层的影响，优化水平MJS设计施工参数，本文以苏州轨道交通6号线某地铁车站富水粉砂地层中MJS试桩工程为背景，采用现场试验的方法研究了水平MJS成桩引起地下水位、超静孔隙水压力、土压力和深层水平位移的变化规律。研究结果表明：试桩期间水平MJS喷浆时超孔隙水压最大增加了46.1 kPa；喷浆使水位最大上升3.6 m，停止喷浆后水位最大下降1.5 m；土压力的变化趋势与孔压一致，喷浆时土压最大上升40.6 kPa。由于粉砂层引孔过程中土体自支能力不足，易塌孔，本次施工中引孔时的测斜最大发生1.2 mm的内倾，喷浆时测斜最大发生了2.2 mm的外倾。苏州某地铁车站水平MJS施工期间车站底板最大位移值为0.8 mm，均满足规范要求。在粉砂层MJS施工过程中可在水泥浆液中加入3%掺量膨润土，防止出现塌孔和抱钻现象。

Metro Jet System (MJS) construction method has the advantages of omni-directional, high-precision, centralized mud discharge, etc., and shows high adaptability under the unfavorable construction conditions such as complex and changeable geology, and traversing existing stations using shield tunneling. In order to study the effects of horizontal MJS pile constructed within silty sand stratum and to optimize the design and construction parameters of horizontal MJS, MJS pile test was conducted in a subway station of Suzhou Rail Transit Line 6. The field test was performed to study the developing trend of groundwater level, excess pore water pressure, soil pressure and deep horizontal displacement caused by horizontal MJS pile construction. The results show thatthe maximum excess pore water pressure increases by 46.1 kPa during horizontal MJS shotcreting during pile testing. The water level will rise by 3.6 m at most during shotcreting, and will drop by 1.5 m at most after shotcreting. The variation trend of earth pressure is consistent with that of pore pressure, and the maximum increment of earth pressure during shotcreting is 40.6 kPa. Due to the insufficient self-supporting capacity of the soil mass during the hole drilling in the silty sand layer, the hole is easy to collapse. During this process, the inclinometer during the hole drilling has a maximum inclination of 1.2 mm, and the inclinometer during shotcreting has a maximum inclination of 2.2 mm. The maximum displacement of the station floor during the horizontal MJS construction in a subway station in Suzhou is 0.8mm, which meets the specification requirements. During the construction of MJS piles within silty sand layer, 3% bentonite can be added to the cement slurry to avoid hole collapse and drilling holding problems.

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江苏省高等学校基础科学(自然科学)研究面上项目（23KJB560023）