Tecnologias para o monitoramento de rejeitos – experiência da Fugro no

desastre de Bento Rodrigues e desenvolvimentos recentes

Alessander Kormann

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Samarco Project - Locations

Source: www.samarco.com/rompimento-de-fundao/

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Samarco Structures – Germano Mine Complex

Germano Mine

complex before

Fundão dam

failure

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Setup of Fundão Dam System, early 2015

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Overview of Germano Complex after Dam Failure, 2016

Sela Dike

Tulipa Dike

Baia 3 Dike

Germano

Main Dam

Selinha Dike

Germano

Buttress

Auxiliary Dike

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Design Principle of Fundão Dam System

A) Initial design of

Fundao-dam system

with separation of course

grained sands and fine

grained suspensions

(slimes)

B) Planned layout

of Fundao-dam system

following upstream

method of construction.

Drainage system within

sandy tailings

Source: Fundao Tailings dam Review Panel

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Fundão Drainage System, 2008

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Source: Fundao Tailings

dam Review Panel

Redesign of Drainage with Blanket Drain, 2009

Installation of

1st Blanket Drain for

drainage of tailings

above an elevation

of 826m

Secondary drainage

galleries not working

properly, detected

2010

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Construction of Setback Crest, 2012

Source: Fundao Tailings dam Review Panel

In 2012 it becames evident

that secondary drainage

gallery at left abutment is

out of function.

A setback crest was con-

structed and a second

blanket drain installed at

Plateau elevation 865

Installation of piezometers

in 2014 showing increasing

saturation of the dam, even

above elevation 865

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Fundão Dam: Principle Stress Situation

Pore water pressure [u]

Load [Mean Total Stress]

Source: Fundao Tailings dam Review Panel

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Fundão Dam: Process of Failure at Left Abutment

σefective = σtotal - u

u ≥ σtotal → σefective = 0

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Principle Stress States, Drained & Undrained

UNSTABLE

STABLE

STEADY STATE

SHEAR STRENGTH

(σ1+σ3)/2 [Mean stress]

CONCEPT OF THE COLLAPSE SURFACE

(σ1-σ

3)/

2 [S

he

ar

str

ess]

5

4

3

2

1

STRESS PATHS INHERENT FROM AN INITIALLY STABLE CONDITION

(σ1+σ3)/2 [Mean stress]

(σ1-σ

3)/

2 [S

he

ar

str

ess]

Adapted from: MARTIN & Mc ROBERTS, 2012

STRESS

PATH

BEHAVIOUR ON

STRESS

ANALYSIS

METHOD

1-2-3 Contractive USA

1-4 Contractive ESA

1-4 Dilative ESA

1-5 Dilative USA

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Technologies for Site Characterization and Monitoring of Tailings

• Geotechnical Investigation (Active):

‒ Drilling (rotary and SPT)

‒ CPT

‒ Vane Tests

‒ Seismic CPT

• Geophysical Survey:

‒ GPR

‒ Electrical Resistivity

‒ Magnetometry

• Geotechnical Instrumentation (Passive):

‒ Casagrande Piezometer

‒ VW Piezometer

‒ Water Level Indicator

‒ Inclinometer

• Laboratory:

‒ Earthworks control

‒ Index tests

‒ Advanced tests

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Cone Penetration Testing (CPT)

signal cable

connection piece

for rod

water proof casing

O-rings

calibrated steel rod

with strain gauges

Inclinometer

Friction sleeve

As = 150 cm²

calibrated steel rod

with strain gauges

O-rings

Cone

Ac = 10 cm²

Penetration of the CPT

cone (hydraulic) into the

ground with a constant

speed of 2 cm/sec

Simultaneous and

continues measurement

of the total penetration

resistance, which is

divided in cone

resistance (qc) and local

sleeve friction (fs)

Additional parameters

can be measured with

added tools

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CPT – Lithologic Interpretation

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Seismic CPT

t = t0

t = t1

t = t2

Δs

Calculation shear wave velocity

t2 – t1 = Δt vs = Δs / Δt

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Degradation of Shear Modulus with Increasing Strain

G0 gemessen mit SCPT

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Germano: Main Dike and Germano Buttress – Performed Investigations

Service

Before

Fundão

Breach

After

Fundão

Breach

Drilling (m) 759.28 1476.52

Water level

indicator

(unit)

4 6

VW

piezometer 0 16

Casagrande

piezometer

(unit)

11 35

Inclinometer

(unit) 0 3

CPT (m) 362.94 134.91

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Cava de Germano – Performed Investigations/Measurements

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Case Study: Tailing Characterization for Re-mining

CPT based Technology

Deliveres geotechnical data

XRF technology - provides metal concentrations

High resolution – real time

3D modelingof resources for remining

Old tailing for remining / resource estimation

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Typical XRF-CPT profile

at Tailing1

CPT-XRF: How it Works

> 1% Cu Target Horizon

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3D Resource Estimation

Metal Distribution within Tailing Body

Metal bearing zone

> 1% Copper

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GeODin

O GeODin foi desenvolvido inicialmente por geólogos e hidrogeólogos para organizar

dados de campos e permitir seu compartilhamento. Atualmente, a Fugro usa o GeODin

em escala global, como ferramenta padrão de gerenciamento de dados.

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Estrutura

Gerenciamento de documentos

Sistema GeODin

Dados dinâmicos Estações meteorológicas

Pontos de controle de rede

Poços

Sondagens

Pontos de monitoramento

Monitoramento

Dados estáticos

GIS

Gerenciamento correto

Servidor do portal

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Monitoramento hidrogeológico com interface WebGis

Túnel Itália - Áustria

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Aquisição de Dados e Integridade

Coleta e exame dos dados: como estão organizados (estrutura), relações entre

conjuntos de dados & realidade física (topologia), origem (metadata).

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Dados Dinâmicos, Análise & Estatísticas

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Rotinas Automatizadas para Relatórios

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Município de Berlin, Alemanha

Gestão de dados regional (130.000 furos de sondagem, 8.000 poços de

monitoramento, piezômetros, qualidade da água subterrânea).

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Base de dados aberta

Dados dinâmicos

Sistema de alerta

Gerenciamento de Barragens, Alemanha

Oito barragens e reservatórios (463 milhões de metros cúbicos). Maior sistema

fluvial integrado do país.

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Companhia Siderúrgica do Atlântico, Brasil

Gestão de dados do

subsolo e de

geomonitoramento

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Considerações Finais

• Importância de abordagens integradas de investigação e

monitoramento de estruturas de disposição de rejeitos.

• Informações integradas: geográficas, geológicas,

meteorológicas, hidrogeológicas, geotécnicas, estruturais

(monitoramento).

• Evolução tecnológica: aumento da segurança na cadeia

produtiva da mineração.

Obrigado!