| 摘要: |
| 【目的】研究黄土场地基坑内水位最大降深和降水工艺对降水效果的影响，为西安黄土梁洼地区深基坑大降深降水设计与施工提供依据。【方法】通过对陕西西安黄土梁洼地区不同管材、不同井径、不同井间距群井抽水对比试验，用潜水完整井稳定流理论分析抽水试验过程，获得场地水文地质参数和基坑内水位最大降深，研究降水过程中渗透系数、基坑总出水量、单井出水量、降水影响半径、井损等的变化特性。【结果】西安梁洼区黄土的渗透系数为4～10 m/d，群井中单井出水量为200～500 m3/d，降水影响半径为150～200 m，降水过程中井损为38.6%～65.5%，降水井间距以15～20 m为宜，基坑内水位降深20 m左右时，降水井深度以不超过50 m为宜。【结论】在西安黄土梁洼区，采用基坑外布置降水井，可以达到基坑内地下水位降深超过20 m的要求，可采用潜水完整井稳定流理论对降水过程进行分析。 |
| 关键词: 黄土地基 深基坑 大降深降水 基坑降水试验 |
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| 基金项目:陕西省重点学科建设专项资金资助项目（No. E01001） |
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| Pumping test for over-deep groundwater lowering in foundation pit in loess site |
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| Abstract: |
| 【Objective】Combining geological and hydrological conditions of Xi’an loess ridge and depression district,the paper studied the possible deepest groundwater lowering and the effect of dewatering techniques on dewatering for the purpose of design and construction of over-deep groundwater lowering in loess foundation pit engineering.【Method】By pumping test of well group with different pipe materials,well diameters and well spacing,the dewatering process is analyzed by complete well steady flow theory to obtain hydrological parameters and the deepest groundwater lowering in foundation pit and variation characteristics of total water yield of foundation pit and single well,depression-cone curves and well loss are studied.【Result】It is found that,in Xi’an loess ridge and depression district,range of permeability coefficient is 4-10 m/d,water yield of one well in well groups 200-500 m3/d,influence radius of dewatering 150-200 m,and well loss 38.6%-65.5%.For the case of groundwater lowering is about 20 m in foundation pit,the well depth and well spacing can be less than 50 m and 150-200 m respectively.【Conclusion】In Xi’an loess ridge and depression district,more than 20 m of groundwater lowering in foundation pit can be achieved by well-points dewatering systems around pit,the complete well steady flow theory can be used to analyze groundwater lowering process in foundation pit. |
| Key words: loess foundation deep foundation pit over-deep groundwater lowering pumping test in foundation pit |
