Innovative Directional Microtunnel Garners Success for

Crucial Trenchless Crossing

Jon Robison, PE, Associate

2

Project Location

WE ARE HERE

I-84 DMT

• Project Vicinity

Geotechnical Conditions

Trenchless Feasibility

HDD

Trenchless Feasibility

Conventional Microtunnel

Design Plan View

Trenchless Design – Curved, Jacked Steel Pipe

• Estimate Jacking Forces• Calculate Pipe Stress

– Axial– Bending (Permalok) – Hoop – Combined

• Evaluate Buckling• Operating Stresses

Estimating Jacking Forces

• When during the drive does the maximum load occur?

• Where is the maximum load?

Jacking Forces = Skin Friction + Face Pressure + Weight of Pipe

Jacking Force Calculations

StationDirect Pipe

Profile

Ground Surface

Elevation

Depth Below GS

(ft)

Incremental Pipe Length

Pipe Length (ft)

Δ Pipe Elevation

(ft)

Pipe Angle, θ

Incremental Weight of Pipe (lb)

Weight of Pipe

Cumulative (lb)

Jacking Force

Weight of Pipe, (kip)

722.451739 1289.528606 1295.532469 6.0 0.0 0.0 0.000000 0 0.00 -4224.04 -4.22730 1288.601796 1295.163619 6.6 7.6 7.6 -0.926810 -0.12217305 -181.90 -4042.14 -4.04740 1287.37395 1294.670263 7.3 10.1 17.7 -1.227846 -0.12217305 -240.98 -3801.17 -3.80750 1286.146105 1294.237783 8.1 10.1 27.8 -1.227846 -0.12217305 -240.98 -3560.19 -3.56760 1284.918259 1294.233573 9.3 10.1 37.8 -1.227846 -0.12217305 -240.98 -3319.21 -3.32770 1283.690414 1294.294626 10.6 10.1 47.9 -1.227846 -0.12217305 -240.98 -3078.23 -3.08780 1282.462568 1294.157645 11.7 10.1 58.0 -1.227846 -0.12217305 -240.98 -2837.25 -2.84790 1281.234722 1294.035948 12.8 10.1 68.1 -1.227846 -0.12217305 -240.98 -2596.27 -2.60800 1280.006877 1293.337974 13.3 10.1 78.1 -1.227846 -0.12217305 -240.98 -2355.29 -2.36810 1278.780149 1292.779574 14.0 10.1 88.2 -1.226728 -0.12206295 -240.76 -2114.53 -2.11820 1277.569551 1292.329791 14.8 10.1 98.3 -1.210597 -0.12047347 -237.59 -1876.94 -1.88

g' (pcf)f

(degrees)

f (radian

s)

C (psf)

Normal Stress,

s'n (psf)

Interface Friction

Factor, m

Incremental Skin

Friction (lb)

Jacking Force due to skin friction

Fr (lb)

Jacking Force due to skin friction

Fr (kip)

Vertical

Stress s v ,

(psf)

Passive

Pressure Pp

(psf)

Jacking force due to

Face

Pressure Fp

(lb)

Jacking Force due to

Face

Pressure Fp

(kip)

Jacking Force due to Face

Pressure near Completion

(kip)

125 38 0.663 50 208.33 0.3 0.0 544005.3 544.0 750.5 3359.86964 18765.1 18.8 37.0125 38 0.663 50 208.33 0.3 4284.7 544005.3 544.0 820.2 3653.0601 20402.5 20.4 37.0125 38 0.663 50 208.33 0.3 5676.4 539720.6 539.7 912.0 4039.01064 22558.1 22.6 37.0125 38 0.663 50 208.33 0.3 5676.4 534044.3 534.0 1011.5 4456.95027 24892.3 24.9 37.0125 38 0.663 50 208.33 0.3 5676.4 528367.9 528.4 1164.4 5099.93198 28483.4 28.5 37.0125 38 0.663 50 208.33 0.3 5676.4 522691.6 522.7 1325.5 5777.20698 32266.0 32.3 37.0125 38 0.663 50 208.33 0.3 5676.4 517015.2 517.0 1461.9 6350.4217 35467.4 35.5 37.0125 38 0.663 50 208.33 0.3 5676.4 511338.8 511.3 1600.2 6931.66799 38713.7 38.7 37.0125 38 0.663 50 208.33 0.3 5676.4 505662.5 505.7 1666.4 7210.09863 40268.8 40.3 37.0125 38 0.663 50 208.33 0.3 5676.3 499986.1 500.0 1749.9 7561.2837 42230.2 42.2 37.0125 38 0.663 50 208.33 0.3 5675.2 494309.8 494.3 1845.0 7961.06738 44463.0 44.5 37.0

Frictional Resistance Face Pressure Resistance

Required Jacking Force - Field Data

Estimated Jacking Forces

Estimated Jacking Force- I-84 DMT• Estimated Jacking Force- I-84 DMT

Design Stresses, Pipe CapacityAnalysis for 400 US Tons Jacking Force 42” OD X 0.750” WT 46 ksi steel pipe

• Construction

I-84 Construction

I-84 DMT Exit

Thank You!Contact Jon Robison at GeoEngineers, Inc.

for more information:jrobison@geoengineers.com