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# Microtunneling

A presentation for Drive System Principles
by

## Joran Schouten

on 11 July 2014

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#### Transcript of Microtunneling

Medium:
Water

Use:
Transport
Cutting aid

Requirements:
3m per hour
Microtunnel diameter:
1,524m (60)
Slurry pipe diameter:
0,1m

Pipe segments
material
concrete
steel
composite
Pipe joint
connecting the segments
connections inside the tunnel
power
water
slurry
bentonite
Slurry transport
Cutting with Disc Cutters
Spacing of Discs
Penetration Depth
cutters penetrate into the rock face
high contact stresses
highly crushed zone of rock material
What is microtunneling?
Unmanned tunneling method
Remote controlled
Tunnel line applied via pipe jacking

Penetration depth calculated with Specific Energy:

SE = Fr/(p*S)
Fr = rolling force
p = penetration depth
S = distance between cuttings
Applications
Pipeline shore approach
Placing a sewer pipe
Sea out fall

Scenario
Brazil oil terminal Ilha d'Agua

Water depth: 12m
Soil depth: 15m
Soil: fine to coarse sand

Microtunneling

By
Thijs Verdoold
Rian Oudewortel
Marco Koole
Niels Bleeker
Joran Schouten
With the penetration depth determined, the normal force can be obtained.

Then, the total thrust can be estimated as:

Ft=Nc*Fn*f
Ft = total trust [kN]
Nc = # of cutting discs
Fn = normal mean thrust [kN]
f = friction loss coefficient (~1.2)

The torque of the cutter head can be calculated with:

T = SUM(r*F)
F = rolling force of each cutting disc
Contents
MTBM specifications
Power source selection
Pipe segments
Jacking system
Slurry transport
Steering of the MTBM

Different types of cutterheads are used for different types of soil:
Calculation slurry pipe pressure

Assumptions:
Horizontal length L = 750m
Total depth H = 15 + 12 = 27m
Soil type: Fine gravel d50 = 2mm
Kinematic viscosity v = 1E-6 m^2/s
Pipe roughness k = 2E-4 m

Method:
MTI holland model
Wilson model

Results:
Deposition limit velocity, V = 2.35 m/s
Delivered concentration, Cvd = 0.17
Max pump pressure, P = 22 bar

MTBM Specifications
Power source selection
Steering
Remotely controlled jacks:
ELS system:
Target and source
Source moves along

Calculation slurry pipe pressure
Engine Selection

An MCA was carried out to select the right Engine:

Holes for lubrication with bentonite
bentonite
Pipe Jacking
face pressure
pressure balance

Wall shear forces
Jacking forces
Prediction models:
Scherle (1977)
Weber (1981)
Bennet (1998)
Chapman (1999)
Osumi (2000)
Force Prediction
Friction States:
static
sliding
fluid (bentonite)
Scherle (1977)
no depth vs forces
Weber (1981)
Chapman (1999)
(non)lubricated
Bennet (1998)
cohesion
Osumi (2000)
Pipe thruster
Jacking station
Bentonite
frictioncoeff:
.6 -> .06
Lubrication
Pump recommendations
For abrasive conditions
Pressure range up to 22 bar
Production range up to 116 m3/h
Settling of slurry
Issue with slurry overflow

Vts by Grace method
Vth by Richardson and Zaki

Resulted in:
Vth = 0.16 m/s
Hydralic engine working principle

How is jamming of the cutter head handled?

Cutter head jamming --> pressure rise in engine

Pressure relieve valve enables engine bypass
Calculation slurry pipe pressure
Full transcript