2008 International ANSYS Conference · 2008 International ANSYS Conference AUTODYN Simulation of Blasting at Pointe du Bois Generating Station ... •A test blast program in March

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2008 International

ANSYS Conference

AUTODYN Simulation of Blasting at

Pointe du Bois Generating Station

Nick Rapolti

Engineering Analyst

SimuTech Group - Toronto

Shaun Beatty, P.Eng.

Senior Structural Engineer

KGS Acres

Ryan Penner, P.Eng.

Project Engineer

Manitoba Hydro


Introduction

• The 97-year old Pointe du

Bois Generating Station is

located in Manitoba,

Canada

• The station is nearing end-

of-life and scheduled to be

replaced.

• Re-development options

include a new powerhouse

and spillway next to the

existing East Gravity Dam


Background

• Re-development currently in the pre-design

phase.

• Construction would involve blasting of the bedrock

foundation near the existing East Gravity Dam.

Potential new

development

layoutExisting

powerhouse

East Gravity

Dam


Objectives

• A test blast program in March 2008 in the

proposed construction area monitored the effects

on the bedrock and existing structures

• The finite element model of the East Gravity Wall

is calibrated from the results of test blasts

conducted on site

• Computer simulations will be employed to better

understand the potential effects of future

construction blasting for bedrock demolition


Model Description

• Dam modeled from

construction drawings

• Ground surface

modeled from

bathymetry and survey

data

• Meshed using

GAMBIT


ANSYS Structural Characterization

• Modal Analyses and Transient Analyses with

forced vibration of base (using ANSYS WB)

• 3D Model shows locations of highest velocity,

helps define locations of sensors in testing

• 2D sensitivity studies of:

– Mesh size

– Concrete properties

– Extent of water modeled

11th Mode (19.3 Hz)


ANSYS Structural Characterization

• Sensitivity studies identified:

– Critical parameters affecting

structural response

– Effect of water behind dam

and amount of water needed


AUTODYN Model

• The main challenge in these simulations is the

range of scales (Ø0.04m explosive, 400m dam)

• Remap process used to start with local fine

model, move to large coarse model

• Initial 2D axisymmetric model is 2x3.5m made

up of rock directly around explosive

• 3D models made large enough

to minimize effect of reflections

off boundaries


AUTODYN Remap Process

• Small 2D axisymmetric model initiates blast

• Blast effects remapped onto larger 2D models

• Largest 2D model after remap is 36x36m

• Results remapped as initial state of 3D simulation


Method of Correlation

• Model adjusted to match

results of test blast

program:

– Peak velocity predicted

by regression line

– Amplification between

base and top of dam


Calibrated Simulation Results

• Preliminary simulation results correlate well with

regression line developed in testing


Blast Propagation in Bedrock

• Pressure waves and velocity vectors vs time


Motion of Structure

• Velocity vectors

over time


Additional Correlations

• Time-History comparison at 85m from blast

• Testing

• Simulation



• Frequency content comparison at 85m from blast

• Testing

• Simulation



• Time-History comparison at top of dam

• Testing

• Simulation



• Frequency content comparison at top of dam

• Testing

• Simulation


Conclusions

• Highest velocity on dam occurs near blast

location although other regions displayed higher

structural amplification of vibrations

• Simulation correlates well with many aspects of

test results.

• The final model is ready for use in simulating new

blasting configurations to validate plans for

construction.

Documents

2008 International ANSYS Conference · 2008 International ANSYS Conference AUTODYN Simulation of Blasting at Pointe du Bois Generating Station ... •A test blast program in March