Report 1

Overview: A set of steady-state analytical solutions of groundwater inflows to open excavations is assembled. The solutions are appropriate for developing preliminary estimates of long-term rates of groundwater flows into open excavations.
The solutions incorporate the following assumptions:

• The aquifer is a continuous porous medium;
• The aquifer is homogeneous and isotropic; and
• Flow is steady and laminar.

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:

1. Flow through a confined aquifer;
2. Flow through an unconfined flow without recharge;
3. Combined confined/unconfined flow;
4. Flow through an unconfined flow with recharge; and
5. Flow through an 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:

1. Flow into a “long” excavation;
2. Flow into an approximately square excavation with a distant recharge boundary; and
3. 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