游洋, 阎长虹, 刘实, 许宝田, 车灿辉, 刘静. 2017: 复杂地质条件下某深大基坑降水方案优化设计. 工程地质学报, 25(3): 715-722. DOI: 10.13544/j.cnki.jeg.2017.03.018
    引用本文: 游洋, 阎长虹, 刘实, 许宝田, 车灿辉, 刘静. 2017: 复杂地质条件下某深大基坑降水方案优化设计. 工程地质学报, 25(3): 715-722. DOI: 10.13544/j.cnki.jeg.2017.03.018
    YOU Yang, YAN Changhong, LIU Shi, XU Baotian, CHE Canhui, LIU Jing. 2017: OPTIMIZATION DESIGN FOR DEWATERING OF LARGE DEEP FOUNDATION PIT UNDER COMPLEX GEOLOGICAL CONDITIONS. JOURNAL OF ENGINEERING GEOLOGY, 25(3): 715-722. DOI: 10.13544/j.cnki.jeg.2017.03.018
    Citation: YOU Yang, YAN Changhong, LIU Shi, XU Baotian, CHE Canhui, LIU Jing. 2017: OPTIMIZATION DESIGN FOR DEWATERING OF LARGE DEEP FOUNDATION PIT UNDER COMPLEX GEOLOGICAL CONDITIONS. JOURNAL OF ENGINEERING GEOLOGY, 25(3): 715-722. DOI: 10.13544/j.cnki.jeg.2017.03.018

    复杂地质条件下某深大基坑降水方案优化设计

    OPTIMIZATION DESIGN FOR DEWATERING OF LARGE DEEP FOUNDATION PIT UNDER COMPLEX GEOLOGICAL CONDITIONS

    • 摘要: 某深大基坑位于长江下游岸边,场地地层为典型的二元结构,基坑开挖涉及的两层承压含水层间的弱透水层局部缺失,之间水力联系密切,基坑场地地质条件极为复杂,基坑施工降水直接关系到基坑工程的安全。这里将基坑分3个区,分别进行降水设计。具体降水方案:Ⅰ区两层承压含水层和Ⅱ区第一承压含水层被围护结构隔断内外水力联系,采用疏干井降水;Ⅱ区第二承压含水层未被围护结构隔断,Ⅲ区两层承压含水层水力联系密切,针对这两个区域设计了两套降水方案,方案一在Ⅱ区和Ⅲ区均布置有降水井,在Ⅱ区对第二承压含水层降水,在Ⅲ区对第一承压含水层降水;方案二仅在Ⅲ区布置降水井对第一承压含水层降水。为了更好地对降水方案进行对比分析,验证方案的可行性,对此进行了数值模拟分析,计算结果显示,两种方案均能满足降水要求,不过方案二布井数量少,基坑外水位降深较小,对周边环境影响更小,优于方案一。

       

      Abstract: A large deep foundation pit, located on the bank of lower reaches of Yangtze River, is of a typical dual structural stratum. An impermeable layer between two confined aquifers involved in the pit excavation is partial loss so that the two confined aquifers have a very close hydraulic connection. Because the condition of the formation under the pit site is very complex, and foundation pit dewatering has a direct influence on the safety of foundation pit engineering. The pit is divided into three zones for separate dewatering design. Here is the detailed plan. The hydraulic connection to the outside is cut off by the retaining structure in the two confined aquifers at Region Ⅰ and the first confined aquifer at zone Ⅱ. Unwatering wells are used in these layers. The second confined aquifer in zone Ⅱ is not cut off, and the two confined aquifers in zone Ⅲ where the impermeable layer is lost, have a close hydraulic connection. Two dewatering schemes are designed for these two regions. In scheme 1, wells are set in zone Ⅱ to pump the groundwater of the second confined aquifer, and in zone Ⅲ to pump the groundwater of the first aquifer. However, in scheme 2, wells are only set in zone Ⅲ and pump the groundwater of the first aquifer. For a better comparison between the two schemes and verifying their feasibility, a numerical simulation is conducted. The results show that both of the schemes are feasible and can lower the groundwater level to 1m below the bottom of the foundation pit. So the two schemes can both meet the requirement of dewatering. But scheme 2 needs less wells and results in smaller water table decline of aquifers outside the foundation pit, so that it has less impact on the environment surroundings, and it's more suitable than scheme 1.

       

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