00406.00 338 Section 00406 - Tunneling, Boring, and Jacking
Description
00406.00Sco pe - This Work consists of installing conduits, pipes, casings, linings, and sleeves by
tunneling, boring, and jacking without excavating the overlying surface.
00406.01Descriptive Terms :
Tunneling - Tunneling includes all methods by which an underground passageway is excavated and lining Materials are brought in and placed.
Boring - Boring includes all methods by which a conduit, casing, pipe or sleeve is pushed or pulled into place and in which the excavation method precludes the stationing of a worker within the conduit without stopping or removing the excavation Equipment . Jacking - Jacking includes all methods by which a conduit, casing, pipe or sleeve is pushed or pulled into place with one or more workers inside to excavate and assist in keeping the conduit on the required grade and alignment.
Materials
00406.10Pipe Beddi ng and Pipe Zone Material - Furnish pipe bedding and pipe zone Material
meeting the requirements of Section 00405.
00406.11Pipe - Furnish pipe Materials meeting the strength, class, and type specified or shown
00406.12Casing - Furnish casing of a size to permit proper construction to the required lines and
grades. Furnish casings that are made of smooth steel pipe or concrete pipe suitable for the purpose intended. Optionally, the casing may be constructed of galvanized, standard-offset, tunnel liner plate with gauge and section modulus as approved.
The class of casing specified is based on the superimposed loads and not on the stresses resulting from jacking or boring operations. Any increase in casing strength to withstand jacking or boring operations shall be the responsibility of the Contractor.
When pressure grouting is specified, equip jacked casings 36 inch diameter and larger with nipples installed at the springline and the crown, at 10 foot centers.
00406.13Grout - Furnish grout for filling the annular space between the carrier pipe and the casing
pipe of one part portland cement, five parts Sand, and seven parts 3/8 inch maximum size rounded Aggregate by volume, or as approved. Furnish grout for pressure grouting outside jacked carrier or casing pipe of one part portland cement and three parts Sand by volume, or as approved.
00406.14Sand - Furnish Sand for filling the annular space between the carrier pipe and the casing
pipe of clean, sharp, and well -graded so that 100 percent passes the No. 8 sieve, and between 10 percent and 35 percent passes the No. 50 sieve, or as approved.
Construction
00406.40Excavation - Excavation for Work under this Section is unclassified and includes whatever
materials are encountered to the depths shown or required.
00406.44 339 00406.41 Required Submittals - Before beginning the Work , submit the following to the Engineer according to 00150.35:
• Tunnel shaft bracing design and dimensions • Tunnel support details • Method of back -packing tunnel supports • Design of bracing to prevent lining from shifting or flotation • Backfill Material or pressure concrete mix design, placement method and Equipment • Poling plate dimensions and details, when required
• Jacking pit construction • Casing or conduit • Jacking head • Excavation method • Tee or wye installation • A substitute design for any part of the system that is changed as a result of the jacking or boring operation • Bracing to prevent pipe shift and flotation, if placed in a casing, and the Materials, method and Equipment for backfilling • Backfill Material or pressure grout mix, placement method and Equipment Submit for review the following stamped Working Drawings :
• Jacking pit bracing • Any Structure that is required because of the particular method or procedure used by the Contractor
00406.42Tunneling - Construct the pipe on a firm Subgrade, thoroughly compacted and true to
grade. If the material in the bottom of the tunnel is ledge Rock , extend excavation of the tunnel to a depth below the bottom of the pipe, and provide a bedding of crushed Aggregate or concrete as specified in Section 00405. Restore to grade any excavation made below grade without approval by backfilling with approved bedding M aterial , at no additional cost to the Agency.
00406.43Boring and Jacking - Boring or jacking may be allowed in lieu of the open trench method
or tunneling with approval of the Engineer. Jack or bore all conduit, casi ngs, pipe or sleeves to the required line and grade.
Equip the leading section of pipe or casing with a jacking head. Perform all excavation entirely within the jacking head.
Should loss of surrounding material occur during the jacking or boring operati on, backpack or grout the voids before the completion of the shift. Fill or backpack all voids with grout or Granular Material as approved.
00406.44Concrete Pipe - Protect the driving ends of concrete pipe against spalling and other
damage. Protect i ntermediate joints by the installation of sufficient bearing shims to properly distribute 00406.45 340 the bearing stresses. Remove all sections of conduit showing signs of failure and replace with new sections, or with approved cast -in-place sections, that are adequate to carry the loads imposed on them.
00406.45Smooth Steel Casing - Join sections of smooth steel casing to be jacked or bored by
welding the joints with a continuous weld for the full circumference, or by other approved means. Provide joints c apable of resisting the jacking or boring forces. Brace pipe installed in casing to prevent shifting or flotation. Fill the void between the casing and the pipe with grout or other Material , as specified or approved.
00406.46Grouting Voids Outside Casing - On pipes 36 inches or larger, fill completely the void
space between the tunnel and the casing or liner plate with approved grout. After the casing or carrier pipe has been jacked or tunneled into position, fill with grout under pressure, through the grout holes provided, to fill all voids outside the pipe using the following sequence:
• Grout at the springline hole at one end and pump the grout until it appears in the grout hole at the crown. • Grout through the opposite springline hole unt il the grout appears at the hole in the crown. • Grout through the hole at the crown until the grout appears in the next set of holes along the pipe. • Plug the holes at the starting point and move to the next set of holes. • Repeat the sequence until the full l ength of the pipe has been grouted. Provide a continuous color video recording of the grout placement, to provide documentation that grout was properly placed according to the above Specifications. On the video, identify the location of the grouting oper ation in relationship to the end of the casing, tunnel or liner plate.
00406.47Cradles for Cased or Tunneled Pipe - Where cradles are shown, provide a strapped
cradle under the barrel of the carrier pipe. The barrel shall bear continuously on the crad les.
00406.48Placing Fill in Casing - Where shown, completely fill the annular space between the pipe
and the casing, tunnel liner or tunnel wall with approved grout or Sand to prevent pipe flotation. Pour or pump the fill from the two ends and from i ntermediate points as necessary. Complete grouting in a continuous operation without stopping. Perform Sand filling using a gunite machine or other approved Equipment .
00406.49Railroad Crossings - Perform all Work in Railroad rights -of-way according to the Railroad
permit.
Measurement
00406.80Measurement - No measurement of quantities will be made for tunneling, boring, or
jacking Work , or for casing or conduit used to install pipe.
Where tunneling, boring, jacking, or open trench excavation is used at the Contractor's option in lieu of another specified method, measurement will be made as originally bid. The quantities of pipe installed by tunneling, boring, or jacking will be measured according to the appropriate items under whic h this Work is required.
00406.90 341 Payment
00406.90Payment - The additional effort required to install conduits, pipes, casings, linings, and
sleeves by tunneling, boring, or jacking (other than under a Railroad) will be paid for at the Contract lump sum amount for the item "Tunneling, Boring, and Jacking". If tunneling, boring, jacking, or open trench excavation is used at the Contractor's option in lieu of another specified method, payment will be made as originally bid.
Payment will be payment in full for f urnishing and placing all Materials, and for furnishing all Equipment , labor, and Incidentals necessary to complete the Work as specified. Tunneling, boring, or jacking under a R ailroad will be paid for according to 00445.91.
Pipe will be paid for according to the appropriate items under which this Work is required.