基础施工方案09.9.2--English.doc

精品 GREAT SOCIALIST PEOPLES LIBYANARAB JAMAHIRIYAThe Housing & Infrastructure BoardContract No: 2008/183 / Project No: 2.13.0028Misuratah Sawawah 5000 Unit Housing Project Method Statement of Foundation Works4th September 2009China Communications Construction CompanyMethod Statement of Foundation Works for Misuratah Sawawa 5000 Unit Housing Project 1. Construction Procedures for Foundation Works Setting-out for buildingExcavation for foundation trenchAcceptance of foundation trench( dimension, elevation, density etc)Concrete cast-in-place for blinding layerAsphalt coating to blinding layer Reinforcement fixing and assembling for the foundation Installation of formworkConcrete casting for the foundation Asphalt coating for the surface of foundation Backfilling in layers2. Construction Methods2.1 Setting-out for building2.1.1 Survey Instrument used DescriptionModelPlanning QuantityCountry of OriginTotal stationLeica 1 SwissElectric TheodoliteDT-028ChinaWater LevelDSZ25ChinaWater LevelDSZ35ChinaSteel Ruler50m10China 2.1.2 Survey staff manning Assignment of survey staffs are as follows:1 chief survey engineer, 2 survey engineers and 6 survey technicians. 2.1.3 Survey method It includes the establishment of plane & level control grid system, observation of survey control grid system, adjustment calculation, re-check of survey control points, setting-out, summary of survey document etc. For details, please refer to the method statement of survey works. 2.2 Foundation excavation 2.2.1 Excavation procedures: excavation compaction of the bottom of foundation trench recondition of foundation trench acceptance 2.2.2 Equipment: backhoe excavator is used for excavation and self-dumping truck for transfer the soil. 2.2.3 Construction method Embedded depth of foundation for the project is 1.2m. Backhoe excavator will be used for one time cutting stop. When the excavation reaches the foot of trench, water level will be applied to control the elevation and the layer of 20-30cm will be reserved for manual excavation to avoid over-excavation. In the process of excavation, proper protection should be done to axial line point and elevation control point. Because the excavated sandstone is easily weathering, a layer of 10cm thick soil will be applied to the bottom of the foundation trench to be compacted by road roller so as to provide consolidated work face for future construction. According to axial line and foundation plan, check the dimension of the foundation trench, recondition the slope and the bottom. Request CM/CS to inspect the foundation trench and made the inspection records accordingly. 2.3 Blinding concrete placing After completion the inspection of foundation trench, blinding concrete placing will be carried out. Blinding concrete shall be compacted by vibration to achieve a flat and smooth surface while the foundation soil shall be kept strictly from direct sunlight. The compressive strength of blinding concrete is C15, with a thickness of 100mm. Water shall be sprayed within 12 hours after concrete placing, and PVC membrane shall be used to cover the concrete for curing. 2.4 Asphalt coating on the surface of blinding layer 2.4.1 Process flow: cleaning the foundation course first coating of asphalt second coating of asphalt acceptance 2.4.2 Construction method Cleaning the foundation course: remove the dust and foreign matter out of the surface First coating of asphalt: have asphalt evenly coated on the surface of the foundation course by using roller paint brush. After 4 hours under normal temperature, if no sticking feeling by hand, second coating of asphalt can applied. Second coating of asphalt : have the second coating evenly in square crossing on the stiffened previous coating layer. Proper protection shall be made timely to the applied coating to avoid any damage.2.5 Fixing and assembling of the reinforcement of foundation G 40 and G60 are used for this project, with diameter 6-25mm. 2.5.1 Process flow Quality inspection of reinforcement making reinforcement burden sheet processing and stockpiling according to steel bar schedule and burden sheet collect the reinforcement according to the type, the size and the quantity used for different position fixing and assembling reinforcement inspection and acceptance. 2.5.2 Construction methods 2.5.2.1 Acceptance of reinforcement delivery 1. Each delivery is provided with quality certificate, delivery certificate and quality inspection report, with furnace number, batch number, date of manufacture, tonnage clearly written. 2. No crack, scab and bending on the surface of reinforcement is allowed, the casting lug on the surface shall be not over than the maximum height of cross rib. 3. Samples of each delivery shall be taken according to the requirement at the presence of CM/CS. Reinforcement shall be processed only after getting approval. 2.5.2.2 Stockpiling and storage Different type of reinforcement shall be stored in different pile and labeled with using position, standard, quantity, dimension etc. The storage area should be leveled and compacted, with block bedding of 40cm higher than ground to prevent the rain and rust.2.5.2.3 Processing reinforcementProcess flow: straightening the reinforcement cutting the reinforcement processing the reinforcement. Steel straighthener is used to make the reinforcement straight. When cutting the reinforcement, longer one should be cut first and shorter one comes second according to the different length of steel bar specified in the steel bar schedule. Baffle shall be used on the work bench to control the length of the reinforcement to ensure the accuracy of dimension. Prior to bending the reinforcement, accurately bending shall be done to the designed shape as per the marks on the reinforcement after calculating the position of bending point. No crack should be found in the bending part. 2.5.2.4 Reinforcement tie-inWay of tie-in: for vertical reinforcement, electroslag pressure welding is applied; for horizontal reinforcement, if diameter16mm, overlap fastening is applied; and if diameter16mm, flash butt welding is applied. 2.5.2.5 Fixing and assembling reinforcement Process flow: place the stirrup for the column assembling vertical reinforcement mark out the spacing between stirrups assembling stirrup 1. Place the stirrup for the column: work out the quantity of stirrup needed for each column according to the space of stirrup indicated on the drawing, place the stirrup at the lower part of protrusive reinforcement and then fix or assemble the reinforcement for the column. Within the range of overlap length, minimum 3 stirrup shall be applied and the open of stirrup shall be towards the center of the column. 2 Assembling of vertical reinforcement: for the vertical reinforcement of column, welding point shall be staggered by 50% as per the Specification, and the space between the upper and the lower joints shall be larger than 35d. 3. Mark out the spacing line of stirrup: mark out the spacing line of stirrup with chalk on the vertical reinforcement of column according to the indication of the drawing. 4. Assembling stirrup: according to the spacing line of stirrup, move the placed stirrup upward and assemble from the top down. Stirrup shall be perpendicular to main reinforcement, and it shall be fixed at the corner of stirrup and the crossing point to the main reinforcement . 2.5.2.6 Cushion block for the reinforcement protection layer Cushion block is made of cement mortar, 50mm50mm, with the same height as the reinforcement protection layer, and with wire embedded in it. 2.5.2.7 Matters need attention1. The minimum anchorage length (Lae) & the minimum overlap length (LLE) of longitudinal tension reinforcement shall be in accordance with the drawing and the Specification.2. The replacement of reinforcement shall strictly comply with the current design specification of reinforcement concrete. If it is replaced in important part, permission from the design department is necessary.2.5.2.8 Quality requirementAssembling the reinforcement according to the diameter, numbers, spaces and location. There should be no deformation, loosening and crack of reinforcement mesh and framework. 2.6 Formwork installation for the foundation The formwork for foundation is assembly steel formwork. Connection between formworks is by type U clip, while reinforced system is the steel pipe with a dimension of 48x3.5mm and fastener accordingly. Before installation of formwork, setting out axial line, side line of formwork and elevation, with the bottom of formwork flattening and firmly. Mould releasing agent shall be coated evenly on the surface of formwork.Check the dimension properly during installation. Install the formwork as per the dimension of structure. After finishing installation, check the planeness, dimension, elevation, joint and reinforcement system carefully.Formwork removal: the soffit formwork shall be only removed when the compressive strength of preserved same conditional curing concrete cube meet the requirement. Side formwork removal: it shall be removed when the compressive strength of concrete would not damage the edge angle due to removal. Under the normal atmospheric temperature, the compressive strength of concrete must reach to 1.2 Mpa, removal time of formwork is about 1215 hours. During removal of formwork, loose the formwork by gentle knock or pry. Hard knock or pry by big hammer is forbidden to avoid the damage of concrete. 2.7 Concrete casting for foundationThe strength class of the concrete for this project is C30 to be delivered to the site by specific transportation vehicle after ready mixing in concrete batching plant. Process flow: raw material test mix design issued by the laboratory concrete mixing concrete transportation concrete casting formwork removal curing.2.7.1 Raw material test: cement, sand, aggregates, admixture and water shall be used only after acceptance of its test result.2.7.2 Test engineer will work out method statement of concrete mix design and submit to CM/CS for approval, and trial mix will be done as per method statement of mix design. It will be used to permanent construction works after the compressive strength of 28 days is accordance to the design requirement. 2.7.3 Baiting and mixing as per approved concrete mix design by CM/CS. It will be delivered to the site by special concrete transportation vehicle after ready mixing. 2.7.4 Make concrete casting by means of concrete pump car. The concrete pump car shall be put into official operation according to correct working procedures after pre-commissioning and checking. During the process of concrete casting, a special person will be assigned to control reinforcement, formwork, support, embedded pipe etc. to protect from displacement and deformation to ensure the quality of concrete. Locate the pedestrian passageway and working platform before concrete casting to forbid stamping directly on the reinforcement. Make homogenous vibrating by poker vibrator.About 24 hours after completion of concrete casting, it shall be striking off by long scraper to design level. Then make second time compaction by wood trowel before initial setting to keep the elevation and planeness of the concrete complying with the requirement. 2.7.5 After 12 hours completion of concrete cast-in-place, it shall be covered by PVC membrane to be cured by water spray properly not less than 7 days. 2.7.6 Lien of concrete cubeTake samples at random in the concrete casting place at the presence of the consultant, to make up concrete cubes for compressive strength test, then made performance test after 28 days standard curing at the presence of the consultant. Quantity of concrete cubes: not less than 1 group for each working shift; not less than 1 group for each continuous concrete casting of a quantity of lOOm3; 3 cubes for each group, with 28 days curing in the standard condition. 2.8 Asphalt coating on the concrete surface of the foundation The process is as same as 2.4.2.9 Backfilling layer by layerProcess flow: Backfilling layer by layer and compaction site test backfilling up to design elevation.1. The materials for backfilling shall comply with the requirement of design without any organic substance, root etc. with moisture content of 10%, if less, water spray shall be applied.2. Backfilling shall be only carried out upon reaching certain strength of the foundation to avoid any damage to the foundation of the structure. Before backfilling, all sundries and building garages inside the foundation trench shall be removed. Before the construction process, elevation points shall be arranged properly. The backfilling of the foundation shall be carried out in two opposite sides or all round to avoid no much difference between the elevation of two sides. 3. Backfilling soil will be compacted layer by layer by means of frog hammer tamping at least 3 times on each layer with a depth of 200250mm. If the loose soil layer is too thick without enough tamping, backfilling soil will be settled to cause ground surface cracking and settlement. 4. During the construction in rainy season, proper measures shall be taken to prevent the water inflow to the trench from ground surface, to avoid landslide of side slope or soaking of soil in the trench. 5. The quality of backfilling shall be in accordance with the requirement of design drawings and the specification.3. Quality assurance measures3.1 Carry out quality standard of ISO9001：2000 carefully, implement quality guideline of the company. Make summary and evaluation to project quality regularly. 3.2 Carry out post responsibility system carefully, strengthen the examination and appraisal of engineer with regard to post responsibility system. Execute the quality reward and punishment by economic means according to the result of the examination and appraisal. The construction quality links personal income to enhance the quality consciousness of construction workers. 3.3 Prior to construction, engineer of each speciality must be familiar with construction drawings to discover and correct the problems found in the drawings in advance and to do proper technical disclosure. The drawings and specification must be respected during the construction. Technical disclosure must be done in writing. 3.4 Establish the site laboratory and set up strict material test system. All the materials entering the site must be sampled and tested according to related requirement and to be used for the construction only after acceptance. Any unqualified materials are prohibited to enter the site. Proper stockpiling and