Hydrogeological assessment of non-linear underground enclosures
Hydrogeological assessment of non-linear underground enclosures
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DOI：
10.1016/j.enggeo.2016.04.012
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发表时间：
2016-06
影响因子：
7.4
通讯作者：
E. Pujades
中科院分区：
文献类型：
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作者：
E. Pujades
地下水位以下的降水通常是通过将挡土墙的保护与抽水威尔斯井的降水相结合来进行的。如果挡土墙有毛病，便会出现严重的困难。因此，必须确定它们的状态，如果需要，修复缺陷或重新设计脱水系统。地下挡土墙的状态可以使用水文地质方法进行评估，但这些方法仅适用于线性开挖。这项工作的目的是提出一个程序来评估非线性地下外壳的状态，通过分析地下水响应抽水外壳内。所提出的方法，这是基于诊断图（相对于时间的对数的压降的导数），允许（1）确定地下非线性外壳是否有孤立的开口或许多缺陷和（2）计算其有效传导性或有效水力传导性。该方法进行测试，在西班牙巴塞罗那的高速列车（HST）隧道的建设所需的轴挖掘过程中收集的数据。该程序可应用于所钻的威尔斯井进行脱水。虽然建议在开挖前进行测试以评估地下挡土墙（水密性评估测试），但该方法可使用在降水阶段开始时收集的数据。
Excavations below the water table are usually undertaken by combining the protection of retaining walls with dewatering by pumping wells. Severe difficulties may arise if the retaining walls have defects. Therefore, their state must be determined and, if needed, the defects repaired or the dewatering system redesigned. The state of underground retaining walls can be evaluated using hydrogeological methods, but these methods are well-established only for linear excavations. The objective of this work is to propose a procedure to evaluate the state of non-linear underground enclosures by analysing the groundwater response to pumping inside the enclosure. The proposed method, which is based on diagnostic plots (derivative of drawdown with respect to the logarithm of time), allows (1) determining if an underground non-linear enclosure has isolated openings or numerous defects and (2) computing its effective conductance or effective hydraulic conductivity. The methodology is tested with data collected during the excavation of a shaft required for the construction of the high speed train (HST) tunnel in Barcelona, Spain. The procedure can be applied using the wells drilled for dewatering. Although a test before the excavation is recommended to evaluate the underground retaining walls (Watertightness Assessment Test), the method can be applied using data collected at the beginning of the dewatering stage.