Below is a detailed procedure for construction of pipe culverts for any kind of road or pavement project. Detailed working drawing will be prepared & submitted for approval for each and every culvert pipe works.
After the site has been surveyed, the limits of excavation shall be set out to true lines, curves and slope as per the project specifications.
In case of re-construction the existing structure will be dismantled after taking the joint measurement of existing structure. In case of widening of pipe culvert only the head wall will be trimmed as per the drawings.
Mandatory Equipment & Machinery
- Excavator / J.C.B. whichever is applicable
- Batching Plant of capacity 30 cu. mtr / hr
- Mixer Machine of Capacity 10/7
- Weigh Batches of Capacity 500 Kg.
- Petrol/Electrical Vibrator & 60 mm Nozzle.
- De-Watering Pumps
- Transit Mixer of Capacity 4 cubic meter
- Other relevant tools
The excavation for foundation bed for pipe culverts shall be done true to the lines and grades shown on the drawings or in accordance with specifications. After completion of the PCC and head wall up to the bottom of the pipe level, the open trench will be cut in existing embankment up to the level shown in the drawings.
In case of high embankments where the height of fill is more than three times the external diameter of the pipe, the embankment shall first be built to an elevation above the top of the pipe equal to the external diameter of the pipe, and to width on each side of the pipe of not less than five times the diameter of pipe, after which a trench shall be excavated and the pipe shall be laid.
The pipe shall be placed where the ground for the foundation is reasonably firm. If the soil at the bed level of the pipe is soft, spongy or other unsuitable soil, it shall be removed to such depth, width and length as directed by the consulting engineer and the extra depth shall be back filled with approved granular material and compacted up to specified level.
If bed-rock or boulder strata are encountered, excavation shall be taken down to at least 200 mm below the bottom level of the pipe.
Excavation shall consist of the removal of the material for the construction of foundation for apron, head wall and other similar structures, in accordance with the requirement of specifications and the lines and dimensions shown on the drawings or as indicated by the Engineer. The work shall include draining and pumping. The removal of all logs, stumps, grubs and other deleterious matter and obstructions, necessary for placing the foundations, trimming of excavations, backfilling and clearing up the site and disposal of all surplus material.
Formwork of required length and size shall be provided for laying and placing of lean concrete layer. Side formwork shall be used for apron as well as the head wall concrete work. All materials for formwork will conform to applicable standards. Formwork shall be removed not earlier than 24 hours after placing of concrete. The design and erection of formwork shall be as per applicable standard and conforming to the Technical Specifications.
Laying of Leveling Course / Head Wall
i. Approved Design mix concrete would be provided.
ii. Till commissioning of our batching plant, Concrete mixer of 10/7 capacity with matching number of weigh batches will be provided in adequate number for concrete production for use in box culverts. Utmost care will be taken to ensure the quality of the concrete.
iii. Adequate number of needle vibrator will be used for proper compaction of concrete.
iv. Leveling course Concrete M15 shall be laid to the thickness of 150 mm to reach the required founding level.
v. After completion of PCC, head wall below sill level (M15 concrete) is laid accordingly as stated above. And after bedding and laying of pipes, Head wall top lift (M15 Concrete) is laid accordingly.
Bedding for Culvert Pipe
The bedding surface shall provide a firm foundation of uniform density through out the length of the culvert conforming to the specified levels and grade shown on the drawing and will be as per the following cases.
Case 1: If the height of the fill of embankment above the top of the pipe is less than 4 m, the bedding will be prepared with granular material.
Case 2: If the height of the fill of embankment above the top of the pipe will be more than 4 M, the bedding will be prepared with PCC.
Culvert Pipe Laying Method Statement
Pipes will be laid in true length and line as per working drawings at the approval of the foundation bed by Engineer. In case of double or multiple pipe culverts the row of pipes shall be separated by a distance equal to at least half the diameter of the pipe subject to a minimum of 450 mm or as per the site conditions. Pipe centers will be matched in case of widening.
The lifting, loading and unloading of concrete pipes will be done by small cranes / JCB at the factory / yard in such a manner that the pipes do not suffer any undue structural strain or damage.
The lowering of the pipe in the bed shall be done with small crane or tripod-pulley arrangement. If above two options are not feasible then the pipes will be laid in the bed manually.
The pipe will be laid from PCL to both directions depending on the case. It will be kept in view that pipe edge towards PCL be at such place that both the ends will be matching to the outer face of the headwalls.
The entire pipe culvert operations will be in accordance with the applicable project specifications/
Culvert Pipe Jointing Method
The pipe shall be jointed by flush joint. Flush joint may be internal flush joint or external flush joint. In either case, the ends of the pipes shall be specially shaped to form a self centering joint with a jointing space 13 mm wide. The jointing space shall be filled with cement mortar, I cement to 2 sand, mixed sufficiently dry to remain in position when forced with a trowel or rammer. Care shall be taken to fill all voids and excess mortar shall be removed
Trench Back Filling Procedure
Immediately after the pipes have been laid and the jointing material has hardened the trench will be back filled. The backfilling will be done in accordance with project specifications.
Back filling up to 300 mm above the top of the pipe shall be done carefully and the soil shall be thoroughly rammed, tamped or vibrated in layers not exceeding 200 mm. The gaps between two adjacent pipes shall also be filled in the same procedure as explained above.
Protection & Curing
As per the specifications, exposed surface of concrete shall be kept continuously in a damp or wet condition by ponding or by covering with a layer of gunny bags or similar materials and shall be kept constantly wet for a period of not less than 14 days from the date of placing of concrete.
Quality Control of Culvert Pipe Works
To ensure the suitability of materials / concrete, tests would be conducted at field/laboratory as per the inspection and test plan.
Health & Safety Requirements & Action Plan
In order to minimize the occurrence of site accident, the provision of a safe working environment for workers to work is essential. Company endeavors to make a zero accident record in each site. In addition to the above, the following safety precautions must also be implemented in achieving the minimization of site accidents.
a) Provisions for workmen:
It is required that all persons working at the site shall be provided with the safety equipment’s, protection means such as safety jackets, hand gloves, safety helmets and other necessary kinds.
All persons working on the site shall be trained by conducting the training course for safety to ensure that they are fully aware of the contents.
b) Provisions for Equipment, Machine:
All equipment will be ensured to operate safely, maintained and repaired periodically. All power equipment should be insulated and covered to all exposed live parts. A competent person shall inspect equipment during shift duty.
c) Provisions for Job Site:
Relevant Caution boards and sufficient lighting system shall be installed at the working area to ensure safety for construction activities at night time.
The working area shall be free from hazards before starting the work. Unnecessary materials such as empty bags and rubbish shall be removed periodically.
Proper safety measures like barricading, guard poles painted with florescent in alternate bands, flags etc. will be provided prior to the commencement of excavation operations.
Signal man will be placed at heavy traffic locations at the time of Execution.
Reflective sign boards will be placed during night near risky locations.
All workers shall be educated in the use of excavators, bulldozers, backhoes, graders and rollers such as the excavator arm & bucket distance and buffer zone in order to prevent from injuries.
Operators would be thoroughly instructed to prevent pushing soil loads into the main road area if any.
Photographs would be taken to disseminate and maintain traffic safety records
Working area will be cordon with traffic cones to identify survey setting out to oncoming traffic on both sides.
During excavation of foundations, if any hard rock is encountered special care shall be taken while blasting.
All necessary measures shall be taken to maintain all plants and silencing equipment in good conditions so as to maintain air and noise emission during the operation.
All necessary measures shall be taken to control the disposal of all forms of waste generated by the construction operations and in all associated activities.
Disposable materials would not be dumped into streams or unauthorized areas. Every effort would be made not to disturb prevailing surface water runoff.
All necessary measures and precautions shall be taken to avoid any nuisance or disturbance arising from the execution of the work.
Level control sheets (if reqd.)
Concrete Pour card / Concrete cube results