Micro Tunneling

Copyright 2005 NASTT

Microtunneling Microtunneling

Best Practices

Quality Assurance / Quality Control

Best Practices

Quality Assurance / Quality Control

Microtunneling • Pipejacking method • Closed­face shield using slurry to remove excavated soil

• Positive face support in unstable soils and under groundwater

• Remote­controlled; no man entry

• Can be stopped by large quantities of cobbles or large rocks

• Steerable • Many jacking pipe options • Diameters: 24” – 90”

Quality Assurance Approach Quality Assurance Approach • Pre­qualify contractors for difficult projects • MTBM must be compatible with ground conditions • Use specialty trenchless construction management • Specifications (if you don’t specify it, it won’t get done)

• Microtunneling • Slurry Disposal • Lubrication • Intermediate Jacking Stations (IJS) • Entry/Exit seals

• Shaft Construction • Pipe Material • Settlement Monitoring • Contact Grouting • Ground Improvement (where necessary)

• Pre­qualify contractors for difficult projects • MTBM must be compatible with ground conditions • Use specialty trenchless construction management • Specifications (if you don’t specify it, it won’t get done)

• Microtunneling • Slurry Disposal • Lubrication • Intermediate Jacking Stations (IJS) • Entry/Exit seals

• Shaft Construction • Pipe Material • Settlement Monitoring • Contact Grouting • Ground Improvement (where necessary)

Pipe Materials Pipe Materials • Reinforced Concrete • Steel • Fiberglass • Polymer Concrete • Clay • Ductile Iron

• Reinforced Concrete • Steel • Fiberglass • Polymer Concrete • Clay • Ductile Iron

Material Quality Control Material Quality Control • Pipe material consistent with soil conditions, surface and installation loads, pressure and corrosiveness

• Pipe manufactured according to ASTM, AWWA standards

• Important dimensional tolerances • Roundness • Straightness • Consistent diameter

• Must have flush joints • Must evenly transmit jacking loads • Lubrication/grout ports • After installation check for line and grade accuracy and damage to pipe or lining

• Pipe material consistent with soil conditions, surface and installation loads, pressure and corrosiveness

• Pipe manufactured according to ASTM, AWWA standards

• Important dimensional tolerances • Roundness • Straightness • Consistent diameter

• Must have flush joints • Must evenly transmit jacking loads • Lubrication/grout ports • After installation check for line and grade accuracy and damage to pipe or lining

Microtunneling Process Microtunneling Process Jacking Shaft 26 x 16 feet typical

Sheet Piles Soldier Piles and Lagging

Auger Drilled (≤20’ diameter) Caissons

Reception Shaft 16 x 14 feet typical

Sheet Piles Soldier Piles and Lagging

Trench Box Auger Drilled

Pipe Material Options Reinforced Concrete

Hobas Polymer Concrete

Steel casing or carrier Clay

Ductile iron

Hydraulic Jacks

Jacking Shaft

Soil Removed

With

Slurry

Receptio

n Sh

aft

Microtunneling Process Microtunneling Process

Machine is

Rem

oved

Construction Duration Jacking Shaft (30’ deep)

2 – 4 weeks

Reception Shaft (30’ deep) 1 – 3 weeks

Reception shafts can be plated until retrieval of MTBM

Microtunneling (per drive) Setup – 10 days

Progress – ~30ft/day­clay; 60 ft/day sand 600’ – 20 days 1300’ – 45 days Retrieval – 5 days

Microtunneling Process Microtunneling Process Equipment

Control Container Generator

Soil Separation Plant Slurry Tanks

Lubrication Plant Pipe Storage

Crane Loader

Dump Truck

Site Preparation Site Preparation • Locate and visually confirm utilities • Pre­Construction Survey (damage and settlement baseline)

• Traffic Control • Spoil Handling and Disposal • Shaft Construction and Safety

• Perimeter Fencing • Traffic Plates or Safety Netting • Tag In/Out for Shaft Entry

• Safety

• Locate and visually confirm utilities • Pre­Construction Survey (damage and settlement baseline)

• Traffic Control • Spoil Handling and Disposal • Shaft Construction and Safety

• Perimeter Fencing • Traffic Plates or Safety Netting • Tag In/Out for Shaft Entry

• Safety

Quality Control During Installation

Quality Control During Installation

• Proper shaft construction

• Thrust block perpendicular to drive

• Laser mounted independent from shaft elements and jacking frame

• Proper shaft construction

• Thrust block perpendicular to drive

• Laser mounted independent from shaft elements and jacking frame

Installation Issues Installation Issues

• Good shaft workmanship • Groundwater controlled, no soil entering shaft

• Maintain line and grade tolerance and limit steering rate to 1:250

• Exit/entry seals • Match excavation rate to penetration rate and soil conditions (no over­excavation or under­excavation)

• Good shaft workmanship • Groundwater controlled, no soil entering shaft

• Maintain line and grade tolerance and limit steering rate to 1:250

• Exit/entry seals • Match excavation rate to penetration rate and soil conditions (no over­excavation or under­excavation)

Microtunneling Inspection Microtunneling Inspection

• Pre­launch inspection of MTBM

• Take measurements multiple times per pipe • Machine drive records • Bag samples of soils from separation plant

• Problems, unusual observations

• Settlement monitoring records

• Pre­launch inspection of MTBM

• Take measurements multiple times per pipe • Machine drive records • Bag samples of soils from separation plant

• Problems, unusual observations

• Settlement monitoring records

Drive Completion Drive Completion • Control soil and groundwater during MTBM retrieval

• Check pipe for proper line and grade

• Test pipe for joint integrity, design pressure

• Construct manholes/junction structures

• Backfill/abandon shafts • Restore ground surface • Air test and video inspect line upon completion

• Control soil and groundwater during MTBM retrieval

• Check pipe for proper line and grade

• Test pipe for joint integrity, design pressure

• Construct manholes/junction structures

• Backfill/abandon shafts • Restore ground surface • Air test and video inspect line upon completion

Consequences of Poor Practices! Consequences of Poor Practices! • Stuck MTBM • Damaged MTBM • Line and Grade Errors • Broken Pipe • Shaft Failures • Settlement / Heave

• Stuck MTBM • Damaged MTBM • Line and Grade Errors • Broken Pipe • Shaft Failures • Settlement / Heave

For Further Information on Microtunneling Equipment & Operations Please Visit

For Further Information on Microtunneling Equipment & Operations Please Visit

Booth 226 & 228 Booth 428 & 430

Booth 615 Booth 208

Booth 623 & 722

Booth 212

Schauenburg MAB GMBH

Booth 327

For Further Information on Jacking Pipe Please Visit For Further Information on Jacking Pipe Please Visit

Booth 626 & 628 Booth 418

Booth 311 Booth 309

Booth 721 Booth 303

Booth 517

Booth 527

Booth 400

Booth 630

Booth 202

For Further Information on Pumping Equipment & Operations Please Visit

For Further Information on Pumping Equipment & Operations Please Visit

Booth 101 Booth 316

Booth 410

Booth 500

For Further Information on Lubricants, Grouting & Sealing

Please Visit

For Further Information on Lubricants, Grouting & Sealing

Please Visit

Booth 313

Booth 301

Booth 416