基坑降水工程设计与实践

电力工程基坑多，深度大，地质条件和施工环境复杂，施工降水已成为深基坑开挖与边坡支护的重要组成部分。作者在基坑降水施工管理实践中发现：以往采用基坑中心水位降低值，预测计算基坑涌水量和基坑水位降深值，只适用于基坑较小、含水层透水性较强场合。当基坑较大，含水层透水性较弱时，基坑在降水施工时地下水位呈凸曲面，再用上述方法计算，基坑涌水量偏小。因此，提出了用基坑周边平均水位降深值预测基坑出水量的计算思路，即采用井点设计降深，计算干扰井影响半径和干扰单井出水量的方法。

Engineering Design and Practice on Precipitation in Foundation Bed

There are many foundation beds in power projects, which have great depth and complex geological conditions and construction environment. The construction precipitation has become an important composition in deep excavation of the foundation and supporting of the side slope. The author has known through the practice of construction management of the foundation precipitation that the former method using the reducing value of central water level in the foundation bed to predict and calculate the surging quantity and level drop in the foundation is only suitable for relatively small foundation beds and places where the permeability of the water-bearing stratum is good. As the foundation bed is large and weak in permeability of the water-bearing stratum and the ground water level looks like convex curve surface for the foundation bed during precipitation construction, the water surging in the bed is smaller by means of the previous calculation method. So the author has put forward a calculation way to predict the precipitation in the foundation bed with the peripheral mean level precipitation of the bed, that is, using the design precipitation at the well point to calculate the disturbance on the well radius effected and disturbance on the water production of a single well.