ProjectDesign verification of

NORTHERN INTERIOR REGIONFORT ST. JOHN DISTRICT OFFICE

CROSSING AND ENCROACHMENT PERMITSFOR CROSSING UNDER CN RAIL (APPROX MARKER 724.5)

NEAR BALDONNEL ROAD & 255 RDFORT ST. JOHN, BC

Assumption:

Dry density of soil, ɣ= 120 pcf

Water table is below the pipe level.

Yield strength of pipe material= 350 MPa.

Modulus of soil reaction, E’ =2000psi

Bending constant, K = 0.1

Deflection lag factor, D1 =1.5

Dead load Calculation:

Earth Dead load pressure on the conduit, Pv =ɣ C

=120x2.3x3.281 psf

=905 psf=6.28 psi

Water table is considered lower than the pipe line.

Live load Calculation:

The pressure transmitted to the pipe from rail load, = 12.15 psi

C= depth of soil cover above pipe= 2.3x3.281=7.54ft

d = offset distance from pipe to line of application of surface load=0 ft.

Impact load:

Impact load factor is considered 1.0. (For more than 3 ft height)

Total load:

Total applied force on the pipe= 6.28+12.15

=18.43 psi

Check:

The moment of inertia of pipe per inch of circumferences is the moment of inertia of the strip 4/8” wide

and 1” long, I= (1/12)x1x(4/8)^3

=0.00439 in4/in

Ovality , = = 0.0141

D= pipe out side diameter=24”

K= bending constant= 0.1 “

Δy= Vertical deflection of pipe, inches

D1=Deflection lag factor =1.5

P = total load on pipe=18.43 psi

E’= modulus of soil reaction, psi =2000psi (assumped)

(EI)eq= equivalent pipe wall stiffness per inch of pipe length. In/lb

Check for through Wall Bending:

Through wall bending stress due to ovalization, σbw=4x29x106x.0167x.375/24= 48022 psi.< 25375 psi. not

OK

This should be less tha .5σy= 0.5x 50750 psi= 25375 psi

Re Calculation with thickness 0.5inch

The moment of inertia of pipe per inch of circumferences is the moment of inertia of the strip 3/8” wide

and 1” long, I= (1/12)x1x(4/8)^3

=0.014 in4/in

Check:

Ovality , = = 0.0093

D= pipe out side diameter=24”

K= bending constant= 0.1 “

Δy= Vertical deflection of pipe, inches

D1=Deflection lag factor =1.5

P = total load on pipe=18.43 psi

E’= modulus of soil reaction, psi =2000psi (assumped)

(EI)eq= equivalent pipe wall stiffness per inch of pipe length. In/lb

Check for through Wall Bending:

Through wall bending stress due to ovalization, σbw=4x29x106x.0093x. 5/24= 22475 psi.< 25375 psi. OK

This should be less tha .5σy= 0.5x 50750 psi= 25375 psi

Ring Buckling from Loads

Allowable pressure for ring buckling

Critical ring buckling pressure, B’ = = 0.203

Critical Stress on pipe, Pc = =

=247 psi

Compressive load =18.43 psi< Pc . OK