Optimization schemes for deep foundation pit dewatering under complicated hydrogeological conditions using MODFLOW-USG

Zhou, C.; Huang, Jintao; Zhan, Hongbin; Wang, Jinguo; Dou, Zhi; Chuanjian, Zhang; Chen, Changsheng; Fu, Yesheng

doi:10.1016/j.enggeo.2022.106653

Cited by 21 publications

(6 citation statements)

References 18 publications

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“…Aquifer drawdown and land subsidence are two critical concerns in foundation pit dewatering projects marked by the presence of thick aquitards (Zhou et al, 2010;Zeng et al, 2021;Chen et al, 2022). Consequently, the pronounced vertical heterogeneity in aquitard K and S s significantly influences the formulation and implementation of dewatering strategies.…”

Section: Discussionmentioning

confidence: 99%

Pumping‐induced Well Hydraulics and Groundwater Budget in a Leaky Aquifer System with Vertical Heterogeneity in Aquitard Hydraulic Properties

ZHUANG,

LÜ,

YAN

et al. 2024

Acta Geologica Sinica (Eng)

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In groundwater hydrology, aquitard heterogeneity is often less concerned compared to aquifers, despite its significant impact on groundwater hydraulics and groundwater resources evaluation. A semi‐analytical solution was derived for pumping induced well hydraulics and groundwater budget with the consideration of vertical heterogeneity in aquitard hydraulic conductivity (K) and specific storage (Ss). The novelty of the new solution is its partitioning of the aquitard into multiple homogeneous sub‐layers to consider various forms of vertically heterogeneous K or Ss. Two scenarios of analytical investigations were explored. One is the presence of aquitard interlayers with distinct K or Ss values, a common field‐scale occurrence. Another is an exponentially depth‐decaying aquitard Ss, a regional‐scale phenomenon supported by statistical analysis. Analytical investigations reveal that a low‐K interlayer can significantly increase aquifer drawdown and enhance aquifer/aquitard depletion. Meanwhile, a high‐Ss interlayer can noticeably reduce aquifer drawdown and increase aquitard depletion. Locations of low‐K or high‐Ss interlayers also significantly impact well hydraulics and groundwater budget. In the context of an exponentially depth‐decaying aquitard Ss, a larger decay exponent can enhance aquifer drawdown. When using current models with a vertically homogeneous aquitard, half the sum of the geometric and harmonic means of exponentially depth‐decaying aquitard Ss should be used to calculate aquitard depletion and unconfined aquifer leakage.

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Section: Discussionmentioning

confidence: 99%

Pumping‐induced Well Hydraulics and Groundwater Budget in a Leaky Aquifer System with Vertical Heterogeneity in Aquitard Hydraulic Properties

ZHUANG,

LÜ,

YAN

et al. 2024

Acta Geologica Sinica (Eng)

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“…To investigate the blocking effect induced by suspended waterproof curtains [23], numerical simulation methods such as MODFLOW finite difference software [24][25][26] have been widely adopted by many researchers. Studies have shown that the hydraulic isolation provided by the curtain is manifested in three key aspects: extending the groundwater seepage path, altering the seepage direction, and reducing the seepage area [27].…”

Section: Introductionmentioning

confidence: 99%

Dewatering Characteristics and Drawdown Prediction of Suspended Waterproof Curtain Foundation Pit in Soft Soil Areas

Chu,

Shi,

et al. 2024

Buildings

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Suspended waterproof curtains combined with pumping wells are the primary method for controlling groundwater levels in foundation pits within soft soil areas. However, there is still a lack of a systematic approach to predict the groundwater drawdown within the foundation pit caused by the influence of these suspended curtains. In order to investigate the variation of groundwater level within the excavation during dewatering processes, the finite difference method is employed to analyze the seepage characteristics of foundation pits with suspended waterproof curtains. Basing on the concept of equivalent well, this study examines the coupled effects of aquifer anisotropy (ki), aquifer thickness (Mi), well screen length (li), and the depth of waterproof curtain embedment on the seepage field distortion. A characteristic curve is established for standard conditions, which exposes the blocking effect of the curtain on the amount of groundwater drawdown in the pit. Additionally, correction coefficients are proposed for non-standard conditions, which, in turn, results in a prediction formula with a wider range of applicability. Comparative analysis between the calculated predictions and the field observation data from an actual foundation pit project in Zhuhai City validates the feasibility of the quantitative prediction method proposed in this research, which also provides a 21% safety margin.

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“…Zhu [18] conducted an experiment on ground subsidence caused by the pumping of confined water in the Tianjin Binhai New Area, analyzing the laws of subsidence of each stratum during the dewatering process. Three-dimensional numerical and fluid-solid models were used to research the impact of different depths of the diaphragm wall on ground subsidence [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Research on Subsidence Induced by the Dewatering–Curtain Interaction in the Deep Foundation Pit of the Shield Launching Shaft in Shenzhen, China

Zhang

Chen

et al. 2023

Water

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The waterproof curtain plays an important role in the dewatering of a deep foundation pit. Recognition of the depth of the waterproof curtain inserted into the confined aquifer at different depths may help control ground subsidence due to dewatering, but subsidence analysis of the interaction between dewatering and the waterproof curtain requires further study. In this study, we mainly analyze the relationship between ground subsidence and dewatering based on the shield shaft pit of the Qianhai-Nanshan deep tunnel project in Shenzhen. Our numerical simulation results show that the ground subsidence around the foundation pit decreases with an increase in the depth of the waterproof curtain inserted into the confined aquifer, and when the waterproof curtain completely penetrates the confined aquifer, the ground subsidence caused by pit dewatering is minimal. Our numerical simulation results are consistent with the actual on-site dewatering monitoring data. Our results suggest that the diaphragm wall is an effective measure to control the ground subsidence in deep foundations, helping to reduce excessive dewatering.

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Optimization schemes for deep foundation pit dewatering under complicated hydrogeological conditions using MODFLOW-USG

Cited by 21 publications

References 18 publications

Pumping‐induced Well Hydraulics and Groundwater Budget in a Leaky Aquifer System with Vertical Heterogeneity in Aquitard Hydraulic Properties

Pumping‐induced Well Hydraulics and Groundwater Budget in a Leaky Aquifer System with Vertical Heterogeneity in Aquitard Hydraulic Properties

Dewatering Characteristics and Drawdown Prediction of Suspended Waterproof Curtain Foundation Pit in Soft Soil Areas

Research on Subsidence Induced by the Dewatering–Curtain Interaction in the Deep Foundation Pit of the Shield Launching Shaft in Shenzhen, China

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