双套管自流深井降水施工技术

Construction Technology of Double Casing Deep Self-flow Well Dewatering

在淤泥质粉质黏土夹粉土地质下的超大型深基坑中,因土体渗透性弱,采用常规自流深井等降水形式,往往出现降水的排水量小、出浑水情况,导致降水效果差,从而影响土方开挖的进度。为解决上述难题,经现场试验,研究分析了降水效果不理想的各种要因,采用粗套管中插入细套管,并结合粗细滤料的二次过滤,优化了常规的设计构造。实践证明,该工艺的改进,实现了出水量大、出清水、降水明显的效果。采用新工艺双套管降水,质量可靠,获得的经验对同地质降水施工有一定的参考价值。

In the super large deep foundation pit under silt silty clay mixed with silt soil,due to the weak permeability of soil,the conventional deep self-flow well and other forms of precipitation often have small drainage and muddy water,which leads to poor dewatering effect and affects the progress of earthwork excavation.In order to solve the above problems,the main reasons of unsatisfactory precipitation effect are studied and analyzed by field tests.The conventional design structure is optimized by inserting a thin casing into the larger casing and combining with the secondary filtration of coarse and fine filter materials.The practice proves that the improvement of the process achieves the effect of large water output,clear water output and obvious precipitation.Using the new technology of double casing dewatering,the quality is reliable and the obtained experience has a certain reference value for the same geological dewatering construction.