喷射早强混凝土施工基坑护壁的逆筑法研究

Study on Reverse Construction Method of Foundation Pit Retaining Wall Constructed by Spraying Early Strength Concrete

目前基坑护壁均采用机械成孔(成槽)灌注混凝土、打入型钢(钢板)桩等方式,基坑开挖范围外需要保证施工机具有操作空间,一般宽度不少于3 m。施工噪声大、扰民,对周边建(构)筑物产生振动,存在一定安全隐患,为此提出喷射早强混凝土施工基坑护壁的逆筑法研究。对位于道路红线内的市政工程深基坑,必须围挡作业,占用部分机动车道。根据交通流量大小,分析是否采取交通疏解措施,给现有机动车通行带来了压力。利用喷射混凝土的早期强度高、无须基坑外施工作业面优点,将其引入基坑护壁,避免钻机等大型机械设备进场、泥浆池的场地设置,从而减少围挡占用机动车道数量,大大缓解了交通疏解压力,增强了文明施工意识,同时也将紧邻建(构)筑物基坑外无施工机具操作空间的项目由不可行变得可行。

At present,the retaining wall of the foundation pit adopts mechanical drilling(trenching)pouring concrete,driving steel(steel plate)piles and other methods.The operating space of construction machines and tools outside the excavation range of the foundation pit needs to be ensured,and the general width is not less than 3 meters.The construction noise is large,disturbing the people,causing vibration to the surrounding buildings(structures),and there are certain hidden dangers.Therefore,the reverse construction method of spraying early strength concrete to construct the foundation pit retaining wall is proposed.For the deep foundation pit of municipal engineering located within the red line of the road,it must be fenced to occupy part of the motorway.According to the traffic flow,it is analyzed whether to take traffic relief measures,which brings pressure to the traffic of existing motor vehicles.Taking advantage of the advantages of high early strength of shotcrete and no need for construction working surface outside the foundation pit,shotcrete is introduced into the foundation pit retaining wall to avoid the mobilization of large machinery and equipment such as drilling rigs and the site setting of mud pits,thus reducing the number of motor vehicle lanes occupied by fences,greatly alleviating the traffic relief force and enhancing the awareness of civilized construction.At the same time,the project with no operating space for construction machines and tools outside the foundation pit adjacent to buildings(structures)is changed from infeasible to feasible.