Experimental investigation on the blocking of groundwater seepage from a waterproof curtain during pumped dewatering in an excavation

• Published in: Hydrogeology journal Vol. 27; no. 7; pp. 2659 - 2672
• Main Authors: Xu, Ye-Shuang, Yan, Xue-Xin, Shen, Shui-Long, Zhou, An-Nan
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-11-2019; Springer Nature B.V
• Subjects: Aquatic Pollution; Aquifers; Computer simulation; Confined aquifers; Dewatering; Dredging; Earth and Environmental Science; Earth Sciences; Effectiveness; Environmental effects; Excavation; Geology; Geophysics/Geodesy; Gradients; Groundwater; Groundwater levels; Hydraulic gradient; Hydrogeology; Hydrology/Water Resources; Laboratories; Laboratory tests; Numerical simulations; Seepage; Thickness; Waste Water Technology; Water Management; Water Pollution Control; Water Quality/Water Pollution; Numerical modeling; Foundation pit; Dewatering; Wall-well effect; Laboratory experiments
• ISSN: 1431-2174; 1435-0157
• DOI: 10.1007/s10040-019-01992-3

The interaction between a waterproof curtain and withdrawal wells (or simply, the wall-well effect) is a key factor in controlling the environmental effects that occur during the dewatering of foundation pits. A series of laboratory investigations was conducted to study the changes in groundwater level during dewatering. The influence of the buried depth of the waterproof curtain placed in a dewatering confined aquifer (
D
), and the filter length of the pumping well (
L
), is investigated. Based on the laboratory test results, numerical simulations are used to analyse the ground settlement. The relationship between the approximate hydraulic gradients on both sides of the wall (Δ
i
), or the ground settlement outside the excavation (
S
), using ratio
R
D
(
D
divided by the thickness of the confined aquifer) or ratio
R
L
(
L
divided by the thickness of the confined aquifer), can be simulated using a Boltzmann curve. The value of Δ
i
increases while
S
decreases with an increase in
R
D
, whereas Δ
i
decreases while
S
increases with an increase in
R
L
. The value of the contraflexure point of the Boltzmann curve is regarded as the effective value of
R
D
or
R
L
. Based on a comprehensive consideration,
R
D
is suggested to be equal to or larger than the effective value, and
R
L
is suggested to be equal to or lesser than the effective value.