一、 工程概况

本期设计为2×600MW亚临界汽轮发电机组。

工程地质情况：本工程持力层采用③圆砾层做持力层，③圆砾，层顶一般埋深3.0m ~4.5m，一般厚度6.5m ~9.5m。④细中砂层，层顶埋深一般为10.0m ~13.0m。一般厚度5.0m~7.0m。⑤圆砾层分布于④层之下。层顶一般埋深15.0m ~18.0m。⑥粘土（残积土），褐色，稍湿，坚硬，覆于凝灰岩之上。最大厚度大于6.8m。

二、 编制依据

《火电施工质量检验及评定标准》

《电力建设施工及验收技术规范》

《建筑施工计算手册》

临时土方开挖图纸 

三、 降水方案选择

该项目地处伊敏河畔，属砂砾地质结构，渗透系数为150m/天，容水量大，受降水影响地下水位波动变幅1-2m 。枯水期在-6m左右。而本工程大部分建筑物埋深在-6m，处于临界状态，丰水期就无法施工，本工程采取的措施是：采用明沟、集水井的方式进行作业层表面水的降水。在枯水期柱、基础底脚施工完、回填完，防止丰水期淹没，以减少降水施工的降水费用。基础埋深超过-6m的，采用局部井点降水。

本工程主厂房基础底标高为-5.0m，不须采用井点降水，而循环水泵坑及汽轮机基础底标高为-7.5m，可采用轻型井点降水。基础平面基底长度约为50m，宽度约为36m。基础埋深为见施工图，地面持力层为圆砾层，井点降水可以避免大量涌水、冒泥、翻浆，而且在砂砾地层中开挖基坑时，可防止流砂现象发生，渗流向下改善土的性质，使基底土质更加密实，结合本工程基础施工主要在枯水期期间，周期较长的特点，采用轻型井点降水法，沿建筑物环状布置进行人工降水。同时基坑二角设集水箱配合4台QY-3.5型潜水泵排除明水的方法。

四、 井点降水相关计算

1、井点管的埋设深度

H≥H1＋h＋iL＋l

式中 H——井点管的埋设深度(m)

     H1——井点埋设面至基坑底面距离(m) 取3.0m

     h—— 基坑中央最深挖掘面至降水曲线点的安全距离(m)取1.0m

     L—— 井点管中心至基坑中心的短边距离(m) 取27

     i—— 降水曲线坡度 取1/10

     l—— 滤管长度(m)取1.2

     H≥3.0＋1.0＋27×1/10＋1.2=7.9m  取8m

......

目录

一、工程概况 ···································································2

二、编制依据· ···································································2

三、降水方案选择·······························································2

四、井点降水相关计算·························································3

五、主要降水设备·······························································6

六、施工工期·····································································7

七、井点施工方法·······························································7

八、质量标准及质量保证措施················································8

九、危险点分析································································10

十、安全生产及文明施工措施···············································10

十一、环保措施································································11