摘 要 上海 实业办公楼基坑工程支护设计，该工程基坑面积1500m2，场地位于上海市西南外围，沿元江路中心线分布，西起沪闵路，东至虹梅南路间.本工程为24层商办楼1栋，16层住宅楼3栋，基坑周长为30×50m，基坑深9.6m。 基坑支护的要求有：保证基坑四周边破稳定性，保护基坑四周相邻建筑物和地下管线在基坑工程施工期间不受损害，保证基坑工程施工作业面在地下水位以上。 如何对此基坑进行支护，可采取如下四种方案：桩墙锚杆支护结构、土钉墙与防渗帷幕支护体系、水泥土搅拌桩支护和SMW工法支护。由于桩墙锚杆支护结构在计算锚杆时锚固段过长，不符实际，予以排除；水泥土搅拌桩，各项系数都已取到最大仍不符合要求，也予以排除；SMW工法比较适用于本工程，但造价较高，且此种方法在国内尚不完善，很多都为经验结果，工程保障不大故也排除不用，最后选用土钉墙支护。土钉墙支护不但可节省造价，且施工快速，方便，无噪音，无环境污染，具有较好的发展前景。 土钉墙可看作一个重力式挡土墙，土钉间距为1.25m，长7.7m，土钉杆直径为32mm，其倾斜角度为12°。止水帷幕为水泥土搅拌桩墙，只是简单的隔水，对强度无严格要求，所以比较经济合理。 Abstract The engineering is bracing of foundation pit design of Shanghai glad industry and commerce office of rainbow building .The foundation pit areas is 1500m2. The building is located the southwestern periphery of Shanghai city , and distributing along Yuan Jianglu#s centre line. The engineering includes is a 24-storey building and 3 16-stroey residence building. The pit perimeter id 30 ×50m, the depth is 9.6m. Requirements of bracing of foundation pit include: ensuring foundation pit slope stability and all around buildings and underground line in bracing of foundation pit construction, and foundation pit construction working face above the groundwater level. How to brace, four kinds of schemes can be adopted as follows: wall anchor pole protrudes to protect structure and soil nail wall and guarding against and oozes that the heavy curtain protrudes to protect system and cement-mixing pile and bracing of SMW method. Soil nail wall is adopted last, because anchorage length of anchor is too long in bracing of piling wall and anchor and cement-mixing pile cannot meet requirement and construction cost of SWM method is too expensive. Not only that soil nail wall can save construction cost, and construction period is short, and convenient, no environment pollution, and also possesses the better development foreground. Soil nail wall can be regarded as the gravity type retaining wall. The soil nail interval is 1.25 m, and the length is 7.7m. Soil nail diamet