Simulation 2: Controlled flooding

(Archive fl2.zip)

The second example shows the application of a pit-specific transient boundary condition.

For this purpose, a retention water level elevation (HMAX) and an external water addition quantity (MENG) are defined for each pit. Both parameters can be changed in the transient input file. If water is added from outside to accelerate flooding, the value of the external addition rate must be entered as a positive value. If the value is negative, water is removed from the pit.

The parameters are defined in the dialogue Attributes Extras Flooding parameters...

If a parameter is to be changed during a simulation, it must first be initialised here.

SPRING dialogue for editing the flooding parameters

To show the working of these flooding parameters the following transient boundary conditions were set:

Table 1: Transient boundary conditions (Flooding 2)

Date	Time step	Boundary condition	Description
01.01.2012	0	HMAX = -50 m MENG = 3068100 m³/year	Start of flooding up to the mine water level at -50 m with a water supply of approx. 8400 m³/day
01.03.2012	60	MENG = -13149000 m³/year	Empty pumping of the pit with a pumping capacity of 1500 m³/h = 36000 m³/day)
01.07.2012	182	HMAX = --46.5 m MENG = 5259600 m³/year	Further flooding up to the pit water level of -46.5 m with an inflow of approx. 14400 m³/day
01.09.2012	244	MENG = 0 m³/year	Flooding without further external addition
31.12.2012	365		End of simulation

The file with the transient boundary conditions can be found in the archive "fl2.zip" and has the following structure (flooding 2):

# SPRING tutorial

# Flooding

# Simulation 2

ZEITEINHEIT MENG JAHR

BEZUGSDATUM 01.01.2012

DATUM

01.03.2012

MENG #empty mine with pumping rate 1500 m3/hour

1-13149000.

DATUM

01.07.2012

HMAX #restart flooding upto mine water level -46.5m

1 -46.5

MENG #add about 600 m3/hour

1 5259600.

DATUM

01.09.2012

MENG #continue flooding without water supply

1 0.5

The results of this simulation are shown in the following figures. They are based on the files "gruben.csv" and "gruben2.xls" ("fl2.zip").

The boundary condition of the external water supply is represented by the "Potential external water supply" curve (corresponds to the definition of the MENG attribute). The "Actual external water supply" curve represents the volume of water that is pumped in or out depending on the physical conditions of the pit. In particular, the actual and possible external water supply differ between reaching the end of pumping out of the pit and the continuation of flooding.

This is due to the fixed external water supply (MENG = 36000 m³/a), which is no longer available once the pit has been emptied). The current pumping rate after emptying the pit is therefore lower (around 22,000 m³/day.

Mine water level, volume change and external water supply (flooding 2)

Boundary condition-dependent mass flows (flooding 2)