全断面注浆管棚矩形冻结加固技术与实测分析

依托南京地铁10号线梦都大街站一号出入口及风道加固工程,经方案比选并针对本工程的水文地质情况及上部横穿敏感结构的特殊条件,提出一种新工法——全断面注浆+顶部管棚+矩形水平冻结加固。通过实测加固土体温度、地表及管线位移,获得了加固土体的温度场分布及地表位移规律。结果表明:矩形侧向冻结壁向内、外发展速度的比值约为1.54;在相同冻结能量和冻结时间内,在粉土夹粉砂层和淤泥质粉质黏土夹粉砂层中冻结壁发展速度的比值约为1.72;冻结孔施工阶段暗挖通道两侧地表沉降量较大,而冻结阶段上方土体受冻胀影响最大;开挖阶段,距开挖面中轴线距离越近,地表沉降量越大,而融沉阶段却相反;地表及管线位移的监测结果表明该工法安全可靠。

Rectangular Freeing Reinforcement Technology of Full-face Grouting Pipe-roof and Measuring Analysis

Based on the No.1 entrance-exit and air passage reinforcement engineering project of Meng-du Street Station of Nanjing Metro Line 10,considering hydrogeology condition and the special condition of crossing upper sensitive structure of this engineering project,comparing several schemes,a new method was proposed-full face grouting + top pipe-roof + rectangular horizontal freeing reinforcement.The temperature field distribution of reinforced soil and the ground surface displacement rules were obtained through the actual measurement of reinforced soil temperature,ground surface displacement and pipeline displacement.The results show that the speed ratio of rectangular lateral frozen wall developing inward and outward is about 1.54.The development speed ratio of the frozen wall in silty soil layer carrying mealy sand and muddy silty clay layer carrying mealy sand is about 1.72 when the freezing energy and freezing time are the same.In the freezing hole construction stage,the ground surface settlement on both sides of underground passage are large,but upper soil is most affected by frost heave in freezing stage.In the excavation stage,the closer the distance to the excavation surface axis,the larger the ground surface settlement is,which is opposite in thawing stage.The results of ground surface displacement and pipeline displacement monitoring show that the method is safe and reliable.