Before start of work, following equipment and machinery shall be arranged for earthwork and monitoring.
- Excavators
- Dump Trucks
- Bull Dozers
- Compactor Rollers
- Settlement Gauges/Settlement Markers
- Survey Equipment
To begin with, licensed surveyor is required to establish the boundary and the temporary bench mark and existing ground level (EGL) all these have to be confirmed by the consultant/client. All confirmed TBMs are to be established in the manner to ensure no disturbance to them. Following this, setting out and clearing would proceed. All surveys carried jointly with consulting engineer. The status of all works completed by Third Party (ies), if any, would be jointly inspected and the status recorded accordingly.
Site Clearance
Temporary main accesses/haul roads would have to be built, and at strategic locations to be joined to existing main logistic road and probably public accesses and this would require close assistant from the client.
All cleared/felled vegetation including debris and other unwanted structures, if any as directed by the client would be carted away from the site to an approved location. Some would be deposited within the site low lying areas, if any, and approved by the engineer with proper compaction to the satisfaction of the client.
Ground Improvement Using Excavation Repeat Method
1st Stage: Sequence of Work for Permanent Backfill Under Platform Slab and Construction of Platform Slab
Step 1
- Excavation of unsuitable material under facial beam to formation level RL:2.30.
- Backfill with sand immediately after excavation.
Step 2
- Erection of Geotextile sand wall with tie back in layer
- General filling until reach facial beam soffit level.
Step 3
- Construction of facial beam cast on top of geotextile sand wall.
- General filling to soffit level and laying of damp proof sheet or lean concrete or approved by consultant engineer.
Step 4
- Construction of platform slab.
2nd Stage: Unsuitable Material Soil Replacement, Track Filling and Surcharge Filling
Step 1
- Excavation of unsuitable material soil from existing ground level to formation level.
- Backfill with sand immediately after excavation to level RL: 4.00
Step 2
- Backfill with suitable soil fill (CBR >= 5%) compacted to specifications.
- Topping up surcharge of 300mm thk.
Instrumentation- Monitoring for Soil Treatment Works
Settlement Markers
Settlement markers would be established in locations selected by the consultant. The permanent settlement reference stations shall be located on stable ground.
Settlement Gauges
- Settlement gauges shall be provided and installed vertically in the positions as directed by the engineer. for the purpose of measuring settlement taking place under and adjacent to the embankments. Settlement gauges shall be installed as shown in the drawings.
- All necessary measures would be taken to protect necessary to protect settlement gauges from damage by plant and vehicles and shall repair any such damage to the satisfaction of the client. A visible barrier at a distance of 750mm around each gauge would be made available.
- Any damaged Settlement gauges would be made available. Would be replaced within seven days or as directed by consultant should any settlement gauge be damaged in such a way as to make it useless for its purpose.
Method of Monitoring
- Monitoring of vertical movements of surface settlement markers and settlement gauges shall be by precise leveling with respect to the permanent settlement reference stations. Provisional locations of the surface settlement markers, settlement gauges and permanent settlement reference stations are given in the Drawings or as directed by engineer.
- Measurement of settlement shall be by use of a approved precise level.
Installation of Instruments
- The method of installation shall be the most advantageous method recommended by the manufacturer and shall be subject to the approval.
- All the instrument such as settlement gauges and permanent settlement reference stations would be installed before commencement of earthworks;
Frequency of Measurement: Frequency of Measurement as stated in BQ (once a week, during construction and once in 2 weeks after construction.
Protection of Instruments: All instruments shall be protected against damage over the period of the Contract. Instruments damaged during the above period shall be immediately replaced.
Instruments Not Functioning: All instruments shall be designed to ensure proper functioning over the period of the contract. Instruments not functioning during the period of monitoring shall be immediately replaced.