design calculations - utility protection - final

SHEET NO.: of

JOB NO.: 212412 JOB: BART SVBX BY: REB Date: Mar. 29, 2013

CALC. NO.: SUBJECT: PROTECTION OF UNDERGROUND UTILITIES CHK’D: DRJ Date: Mar. 29, 2013

General: Due to the proximity of the Chevron and MCI utility lines to portions of the SVBX trenches and structures, a general concern has been raised with regards to the surcharge loads induced by equipment moving over theses buried utilities. Therefore, a request was made to determine the feasibility and to propose possible methods to divert equipment surcharges around the utilities using load bridging methods. The methods presented in these calculations, which include steel plates or crane mats, are intended to completely divert equipment surcharge loads around the utilities, thus having the utilities feel no additional load. Analysis: The general method of bridging the construction loads consists of steel plates or crane mats which are supported at the ends by support pads consisting of 3”x timbers. It is assumed that the surcharge loads will not extend past a 1:1 slope off of the edge of the support pads. The span of the utility bridge is set such that the 1:1 load influence slope does not interfere with the utility, as shown in Figure 1. A two-foot nominal utility diameter has been assumed for this study. In this study, a utility that is at a certain depth, the utility bridge must span twice the depth plus two feet to divert the loads around the utility. Two utility bridge setups have been presented in these calculations, as shown in Figure 2:

1. (2) 1”-thick grade 36 steel plates, stacked, 48” wide. 2. Crane mat consisting of (4) 12”x12” timbers attached side-to-side, Douglas Fir North

Group II. The length of this span is limited based on the load onto the utility bridge and the flexural strength of the bridge. The design calculations which are presented in Appendix B provide allowable point and distributed loads across the utility bridge for the steel plates and the crane mat for a range of utility depths and utility bridge free spans. The analysis is in terms of a four foot width of utility bridge, thus the allowable loads should be compared to one side of a vehicle axel or track load. The analysis assumes the beam member is supported at the midpoint of the support pads with pinned reactions, as shown in Figure 1. The crane mat can hold 4 times the allowable point load than the steel plate setup, and between 2.3 to 4 times the allowable line load depending on the span of the utility bridge that was analyzed. Required Support for Possible Sheet Pile Rigs: In addition to the non-specific limit value calculations made in the above analysis, we have also analyzed bridging scenarios based on two potential equipment options for the sheet pile

SHEET NO.: of



installation at the Montague trench. The information for the potential sheet pile rigs was provided by SSHJV is as follows:

ABI TM 18/22 Hitachi ZX520 excavator with Dutch Masters PVE 2312VM vibro hammer

The rig weights, track dimensions, and other pertinent physical information was taken from the machine specifications provided to SSHJV by the sheet piling contractor and have been included in Appendices C and D. For these specific calculations, a line load from each of the rigs’ tracks was estimated by dividing half of the rig’s rigged weight by the track length multiplied a factor of 1.2 to account for possible uneven loading. These specific calculations are shown in the Appendix E and are summarized below:

Sheet Pile Rig

(2), 1"-Thick, Grade 36 Steel Plates

Crane Mat with (4) 12"x12" Timbers

Maximum Utility

Bridge Free Span (ft)

Corresponding Maximum

Utility Depth (ft)

Maximum Utility

Bridge Free Span (ft)

Corresponding Maximum

Utility Depth (ft)

ABI TM 18/22 6 2 14 6

Hitachi excavator setup

4 1 12 4

It can be seen from the above results that the steel plate option can only span a very small distance, thus making it an impractical option for bridging utilities for equipment of this size. The crane mat option shows much more favorable results being able to successfully span utilities located up to six feet below ground for the ABI rig and up to four feet below grade for the Hitachi excavator setup. For a condition where the utilities are deeper than that allowed by the methods presented here, further analysis would be required which would allow some increase of the ground pressure at the utility. This analysis can be undertaken at a later date based on the specific conditions at a known crossing point.

SHEET NO.: of



Appendix A – Figures

SHEET NO.: of



Appendix B – General Utility

Protection Calculations

DESIGN CALCULATIONS File No.Date

Client: SSHJV Calced by: R. BerendsProject: BART SVBX Checked by: D. JenevienSubject: Utility Protection

Steel Sheet Supports: Allowable Loads

Steel Sheet Properties

Thickness, t 1 in

Width, w 48 in

# stacked 2A 96 in2 =t*w

Z 24 in3 =w*t2/4

fy 36 ksi

fv allow 12.9 ksi = 0.6 * fy / 1.67

Vallow 1242 kips = fv allow * A

fb allow 21.6 ksi = fy / 1.67

Mallow 43.1 k*ft = fb allow * Z

Width of Support, W 2 ft

10 22 24 103.5 0.60 0.60

8 18 20 124.2 0.87 0.87

6 14 16 155.2 1.37 1.37

4 10 12 206.9 2.46 2.46

2 6 8 310.4 5.75 5.75

Depth to Top of Utility

(ft)

Free Span, L1 (ft)

Design Span, L2 (ft)

Allowable Line Load (kip/ft)

Shear LimitMoment

LimitAllow limit

10 22 24 2483 7.2 7.2

8 18 20 2483 8.6 8.6

6 14 16 2483 10.8 10.8

4 10 12 2483 14.4 14.4

2 6 8 2483 21.6 21.6

3/28/2013212412


(ft)

Free Span, L1 (ft)


Allowable Point Load (kips)

Shear LimitMoment

LimitAllow Limit



Crane Mats for Support: Allowable Loads

Timber Properties: (4) 12"x12" Timbers, Douglas Fir Larch (North) Group II

Thickness, t 12 in

Width, w 48 in

# stacked 1A 576 in2 =t*w

S 1152 in3 =w*t2/6

fv allow 0.14 ksi

Vallow 53.8 kips = fv allow * A * 2/3

fb allow 1.80 ksi

Mallow 173 k*ft = fb allow * Z

Width of Support, W 2 ft

10 22 24 4.5 2.4 2.4

8 18 20 5.4 3.5 3.5

6 14 16 6.7 5.5 5.5

4 10 12 9.0 9.9 9.0

2 6 8 13.4 23.0 13.4


(ft)

Free Span, L1 (ft)



Shear LimitMoment

LimitAllow limit

10 22 24 107.5 28.8 28.8

8 18 20 107.5 34.6 34.6

6 14 16 107.5 43.2 43.2

4 10 12 107.5 57.6 57.6

2 6 8 107.5 86.4 86.4

2124123/28/2013


(ft)

Free Span, L1 (ft)


Allowable Point Load (kips)

Shear LimitMoment

LimitAllow Limit

SHEET NO.: of



Appendix C – Specifications for

API TM 18/22 Rig

SHEET NO.: of



Appendix D – Specifications for Hitachi

ZX520 with Dutch Masters Vibro Hammer

SHEET NO.: of



Appendix E – Pile Driving Rig Utility Protection Calculations



ABI TM 18/22 Rig Loading

Rig Weight: 148 kipsVibro Hammer Weight: 12 kipsTotal: 160 kips

Track Length: 17.5 ftTrack Line Load: 4.57 k/ft

Uneven Loading Factor: 1.2Design Track Line Load: 5.49 k/ft

NOT OK

NOT OK

OK

OK

OK


10 22 24 0.6 NOT OK 2.4

8 18 20 0.9 NOT OK 3.5

6 14 16 1.4 NOT OK 5.5

4 10 12 2.5 NOT OK 9.0

2 6 8 5.7 OK 13.4


(ft)

Free Span, L1 (ft)


(2) 1'' Thick, GR36 Steel Plates

Crane Mat: (4) 12"x12" Timbers, Douglas Fir Larch (North) Group II

2124123/28/2013



Hitachi ZX520 Excavator with Dutch Masters Vibro Hammer Loading

Rig Weight: 174 kipsVibro Hammer Weight: 6 kipsTotal: 180 kips

Track Length: 14 ftTrack Line Load: 6.43 k/ft

Uneven Loading Factor: 1.2Design Track Line Load: 7.71 k/ft

NOT OK10 22 24 0.6 NOT OK 2.4

NOT OK

8 18 20 0.9 NOT OK 3.5 NOT OK

6 14 16 1.4 NOT OK 5.5

OK

4 10 12 2.5 NOT OK 9.0 OK

2 6 8 5.7 NOT OK 13.4

2124123/28/2013


(ft)

Free Span, L1 (ft)



(2) 1'' Thick, GR36 Steel Plates

Crane Mat: (4) 12"x12" Timbers, Douglas Fir Larch (North) Group II

design calculations - utility protection - final

Documents