Steady-State Analytical Solutions for Groundwater Inflows to Open Excavations
The Open Excavation Flow Calculator package comprises two reports and two spreadsheets that document and implement steady-state analytical solutions of groundwater inflows to open excavations. The solutions are appropriate for developing preliminary estimates of long-term rates of groundwater inflows to support the selection of groundwater control methods.
Report 1 and its companion spreadsheet, Analytical solutions for flow into open excavations_1_v02.xlsx, contains 10 solutions for 5 conceptual models for confined and unconfined aquifers. Two additional solutions are included for estimating inflows to the base of a circular excavation. The report includes complete references and derivations of the solutions.
Report 2 and its companion spreadsheet, Analytical solutions for flow into open excavations_2_Software.xlsx, contains 3 approximate solutions for estimating groundwater inflows to rectangular excavations in confined aquifers. The analyses follow the approach of Powrie and Preene (1992).
Report 1
Overview: Ten solutions are presented for two cases: flow into the sides of a long excavation (linear flow) and flow into the sides of a circular excavation (radial flow). Solutions for five conceptual models are provided for each of these two cases:
- Confined aquifer;
- Unconfined aquifer without recharge;
- Combined confined/unconfined flow;
- Unconfined aquifer with recharge; and
- Aquifer that is overlain by a leaky aquitard.
Two additional solutions are presented for the estimation of the flow into the base of a circular excavation. References for the solutions are provided. For completeness, the derivations of the solutions are included in appendices.
Report 2
Overview: There are no closed-form analytical solutions for flow into rectangular excavations. Based on the work of Powrie and Preene (1992) approximate approaches for estimating the steady groundwater flow into rectangular excavations in confined aquifers are developed for three cases:
- Flow into a “long” excavation;
- Flow into an approximately square excavation with a distant recharge boundary; and
- Flow into an approximately square excavation with a nearby recharge boundary.
REFERENCE
Preene, M. and Powrie, W. 1992. Equivalent well analysis of construction dewatering systems. Géotechnique, 42 (4), 635-639. doi: 10.1680/geot.1992.42.4.635
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