为解决在低净空内实现大直径MJS垂直桩的施工精度与质量控制难题，针对该工法在珠三角城际轨道交通新白广机场T1—T2区间盾构下穿机场地下通道工程中的应用，开展施工技术研究。首先根据项目概况与地质条件，制定本次下穿方案与土体预加固作业安排。然后，针对本工程中的MJS施工难点，对关键控制技术进行研究。最后，分别从成桩质量、结构位移、效益评价3方面综合分析其加固效果。研究结果表明： 1）通过改造吊物装置系统，可在低净空内实现加固作业，极大地提高施工适应性； 2）采用特制的合金钻头与主机水准仪可实现高精度成孔，且使用高压注浆系统可实现大直径优质桩体； 3）改进后的MJS工艺既保证了加固效果，又可有效规避地下障碍物及管线，其微扰动效果也确保了施工期间机场地下通道结构的正常通行。
To improve the construction accuracy and quality of
largediameter metro jet system(MJS) vertical reinforcement under a low
clearance, a case study is conducted on the Airport T1~T2 Section on the
XintangBaiyun AirportGuangzhou
North Railway Station of Intercity Railway in Pearl River Delta, and
construction technologies are introduced. First, according to the project
overview and geological conditions, the undercrossing
scheme and the soil prereinforcement arrangement are
determined. Then, the construction challenges and essential construction
control technologies are studied specifically. Finally, the reinforcement
effect is comprehensively examined from three aspects: pileforming quality, structural displacement, and benefits evaluation.
The research results show the following: (1) By transforming the lifting device
system, the reinforcement construction can be realized under low clearance,
thus greatly improves the construction adaptability. (2) The speciallydesigned alloy drill head and the level can realize poreforming with high precision, and the highpressure
grouting system can realize the highquality pile with
large diameter. (3) The improved MJS process not only ensures the reinforcement
effect, but also effectively avoids underground obstacles and pipelines, and
its microdisturbance effect also ensures the normal
operation of the underground passage during construction.
