Method Statements-----토공사, 펜스 공사, 옹벽 공사

1. Earthworks

   1-1 Clearing and grubbing

All surface objects and all trees, down timber, rotten wood, stumps, roots, snags, brush, other vegetation, rubbish, and other protruding obstruction, not designated to remain, shall be cleared and/ or grubbed, including disposal as required.

In areas under embankments, from which top soil or unsuitable materials are to be removed or which are designated to be compacted, all stumps and roots shall be removed to a depth at least 30cm below the original ground surface.

In cut areas, all stumps and roots shall be removed to a depth of not less than 30 cm below the finished subgrade level.

               1-2 Stripping  

In area under embankments or where designated by the drawing, the Contractor shall remove the topsoil and dispose of it as directed by the Consultant.

In general the removal of topsoil shall include only the removal of soil which is sufficiently fertile to encourage or sustain a growth of vegetation.

Removal of topsoil over any designated area shall be executed to the depth of 20cm, and the topsoil shall be kept separate from other excavated material.

1-3 Cut and Fill

Common Excavation shall consist of all excavation within the limits of the factory area except. Structure Excavation; the removal, handling and proper utilization or disposal of all excavated materials and shaping of excavation and preparation of exposed surface of excavation, in accordance with these Specifications and the lines, levels, grades, dimensions and cross-section shown on the drawings and as required by the Consultant.

When so directed in writing by the Engineer, the Contractor shall remove material unsuitable for use in the embankment and shall dispose of it as provided in Consultant.

Before the construction of the embankment is begun, the Consultant may order the compaction of the cleared surface or that resulting after removal of the topsoil, in which case the density after compaction shall conform to the requirements. If the material of the cleared surface cannot be compacted to the requirements, the Consultant will specify remedial works when requested. While a soft ground is encountered, a few months surcharge preloading may be a considerable alternative.

Material for embankments, obtained and approved as provided above, shall be placed in horizontal layers of uniform thickness over a width determined by the Consultant and in conformity with the lines, grades, sections, and dimensions shown on the drawings. The layer of loose material other than rock shall be not more than 30 cm thick, unless the compacting equipment used is capable of compacting a depth greater than 30 cm to a uniform density through the full depth which is acceptable to the Engineer, in which case the Contractor may place and compact the material other than rock, in layers of thickness approved by the Engineer. After adjustment of the moisture content to that required to obtain maximum density, the loose material shall be compacted to the required density.

1-4.Trimming of slope

Loose earth or loose rock shall be removed from slopes when required by the Consultant. He may also order the removal of material resulting from landslides, the construction of benches in or above the cut slopes, or, where in his opinion the slope, after cutting, show sign of instability, the flattening of the slope.

 

                1-5 Disposal of bad material.

All other timber, except timber to be used, and all brush, stumps, roots, logs, and other refuse from the clearing and grubbing operation shall be disposed of at locations provided by the consultant in an approved manner. Burning shall not be permitted.

The factory area and adjacent areas shall be left with a neat and finished appearance. No accumulation of debris shall remain on or adjacent to the fence.

      

1. Fence Work

 Bore Pile shall be firmly set after digging holes by means of auger or other equipment at the location of fence post. The drilling machine shall be such that the hole can be maintained exactly vertical during drilling operation. During the placing of concrete in the hole, the verticality and position of the reinforcement shall be carefully controlled to prevent collapse of the drilled hole or damage to the hole.

Stones shall be washed with water before placing. A mortar bed shall be spread on the sides of adjacent stones before the next stone is laid. The location of block out for post should be exacted on the top of Bore pile.

When posts are to be set in concrete or masonry, all details of performed openings and the method of fixing the post therein shall be as shown on the Drawings.

Posts holes shall be backfilled using material according to the details on the drawings. Backfill material shall be thoroughly compacted to the same degree of compaction as the adjacent soil.

The surface of precast panel shall be good conditions and not be detected any crack and fault.

Barbed wire and chainlink netting shall be securely fixed to steel posts with suitable metal fittings including steel connecting places at joints of steel angles, at corners and at end of fence bolted as required, materials and workmanship to be approved by the Consultant.

 

       3.  Retaining Wall Works

Trenches or foundation pits for structure or structure footings shall be of sufficient size to permit the placing of structure or structure footings of the full width and length shown. The sides of trenches or pits shall be adequately supported at all times. The elevations of the bottoms of footings as shown on the Drawings shall be considered as approximate only and the Consultant may order, in writing, such changes in dimensions or elevations of footings as may be deemed necessary to secure a satisfactory foundation.

On completion of the structure, excavated areas shall be backfilled with approved material to the level of the finished ground surface.

Preparation of foundations shall conform to the details as shown on the Drawings. The elevations of the bottoms of footings as shown on the Drawings ate approximate only and the Consultant may order further excavation as necessary to obtain satisfactory foundations.

Pile foundations shall be constructed in accordance with the provisions set out in the other relevant Clauses and as shown on the Drawing.

Internal forms shall be fixed in the correct position such that they will not displace or deform during placing concrete. U-shape bolts shall be used to fix the internal forms and the method of supporting and fixing the internal forms shall be approved by the Consultant. Care shall be taken to ensure that U-shape bolts and other items can resist the buoyancy of the formwork.

The Engineer shall inspect and approve all reinforcement in place in accordance with the requirements of Specifications, before Concrete is placed. An Experienced steel fixer shall be present while all concrete is placed to ensure that no reinforcement becomes displaced during placing and if it does to reposition reinforcement before placing continues.

Walls and other such structural members allow horizontal construction joints, concrete shall not be placed on top of other concrete which has not been allowed to set for 12 hours or more.

Before concrete is placed in sidewalls, bottom slabs shall be cleaned of all shavings, sticks, sawdust and other extraneous material.

At horizontal construction joints, details shall be as approved by the Consultant. Before placing fresh concrete the surface of construction joints shall be sandblasted or washed and scrubbed with a wire brush to expose clean aggregate, drenched with water until saturated, and kept saturated until the new concrete is placed. Immediately prior to placing new concrete the forms shall be drawn tight against the concrete already in place. Concrete in substructures shall be placed in such a manner. That all horizontal construction joints will be truly horizontal.

Where vertical construction joints are necessary, reinforcing bars shall extend across the joint in such a manner as to make the structure monolithic. Special care shall be taken to avoid construction joints through paneled wing or other large surface which are to have an architectural finish.

 

Geotextile shall be laid as  per drawing and overlapping is more than specifications and stretched to prevent movement and wrinkle during fill placement. After the  placing of geotextile the backfill material shall be laid  with a compacted lift t=200mm.