衡重式、仰斜式挡土墙施工方案-英文版.docx

Quality ManagementDocument No.CHEC-NSH-MS-009 Rev Method Statement for Retaining Wall WorksCHECMETHOD STATEMENTFORRETAINING WALL WORKSSECTION 1A KINGSTON TO LINSTEAD321Rev.DateStatusPrepared By Reviewed By Construction ManagerApproved ByProject ManagerREVISION TABLEPAGEREVISIONPAGEREVISIONAPPENDIXREVISIONABCDEABCDEABCDE126A227B328C429D530E631F732G833H934I1035J1136K1237L1338M143915401641174218431944204521462247234824492550SECTIONCONTENTS TITLEPAGE1SCOPE OF METHOD STATEMENT42SCOPE OF WORKS53EQUIPMENT AND MATERIALS53.1Equipment53.3Materials64REFERENCE DOCUMENTS64.1Specifications64.2 Design Report64.3Design Drawing74.4Inspection and Test Plan75CONSTRUCTION AND OPERATION SEQUENCE75.1-5Operations Sequence7-126ACCEPTANCE REQUIREMENTS136.1Visually Testing and Acceptable Tolerance136.2Test Frequency137ENVIRONMENT AND SAFETY14APPENDIX A - ENVIRONMENTAL RISK ASSESSMENTAPPENDIX B - SAFETY RISK ASSESSMENTAPPENDIXPage 3 of 121 SCOPE OF METHOD STATEMENTThe types of retaining wall includes：Inclined Embankment Retaining Wall -4606.0m/100m of C20 rubble concrete, Inclined Embankment shoulder Retaining Wall- 1723.1m/80m of C20 rubble concrete and balance weight retaining wall-14625.9m/905m of C20 rubble concrete：Table 1-Embankment Retaining Wall CHAINAGELENGTH（m）C20 RUBBLE CONCRETE（m）TYPESDRAWING NO.K7+200K7+260604606.02INCLINEDS1-3-28Table2- Embankment Shoulder Retaining Wall CHAINAGELENGTH(m)C20 RUBBLE CONCRETE（m3）TYPESDRAWING NO.K6+910K7+0601502082.1BALANCE WEIGHTS1-3-28K8+540K8+620801723.1INCLINEDS1-3-28K12+873K12+940671358.5BALANCE WEIGHTS1-3-28K13+380K13+440601463.1BALANCE WEIGHTS1-3-28K14+700K14+9002003157.8BALANCE WEIGHTS1-3-28K15+050K15+090401106.6BALANCE WEIGHTS1-3-28K15+200K15+3101101298.9BALANCE WEIGHTS1-3-28K15+340K15+38040711.7BALANCE WEIGHTS1-3-28K15+715K15+76045691.8BALANCE WEIGHTS1-3-28K15+787K15+9801932755.4BALANCE WEIGHTS1-3-282 SCOPE OF WORKSThe construction procedure is shown as below：2.1 Construction preparation2.2 Measurement lofting2.3 Excavation of the foundation pit 2.4 Bearing capacity testing of foundation2.5 Formwork2.6 Installation of drain pipe2.7 Concrete pouring (placing rubble stone)2.8 Removal of formwork2.9 Concrete curing3 EQUIPMENT AND MATERIAL3.1 EquipmentNo.Equipment nameBrand and modelparameterquantityunitremark1ExcavatorPC350198KW,load capacity 1.9m31setWith hook2ExcavatorPC220150KW1setHydraulic hammer3LoaderSHANTUI SD16092KW，3ton 1.8m31set4Batching plantHZS5050m/h1set5Dump truckZHONGQI19.32m3，340 horsepower2set6Concrete truckZHONGQI8m2set3.2 Material3.2.1 C20 rubble concrete 20955m3.2.2 50mm PVC pipe 8074.3m3.2.3 Rubble stone 5238m3.2.4 2cm Board3.2.5 Pre-burying Rebar of Barrier4 REFERENCE DOCUMENTS4.1 SpecificationGuide Specifications for Highway Construction, 9th Edition807 section retaining wall and 808 section concrete structure4.2 Design Reporti) Preliminary Geological Investigation Report-Outline Design Volume 0ii) Environmental Management and Monitoring（EMMP）:CHEC-EMMP-S3-001iii) Method Statement Erosion Control/Sediment Mangement（Document No.EC-SM002）iiii) Quality Plan CHEC-NSH-QP-0002-Diiiii) Calculation Sheet for Retaining Walls(to be developed)4.3 Design DrawingsDrawings may be updated; in such case the recent revision will be used.ROWGeneral LayoutReferrence No. S1-3-28Sub-Grade Cross SectionsRefernce No. S1-3-28Retaining Wall DetailsReference No. S1-3-28 4.4 Inspection and Test Plan Inspection and Test Plan for Retaining Wall Works(to be developed)5 CONSTRUCTION AND OPERTION SEQUENCE5.1 Construction Preparation5.1.1Drawing examination and original landscape retest, if any incorrect drawing or site inconsistency with design is found, make a timely report and arrange review.5.1.2Makeshift road construction，preparation of material stacking field and material preparation,Construct a temporary construction access, furnish material stacking yard and spare materials.5.2 Survey and Staking-out5.2.1Carry out survey and staking-out, and identify the line of excavation boundary.5.2.2Dispose all weeds, rubbish and other obstruction within the scope of retaining wall; dig drainage ditch around foundation trench, and eliminate surface water. 5.2.3Make good drainage arrangement before base excavation, during which keep drainage in a good condition, ensuring that water hazard is prevented during construction.5.3 Excavation of Trench Foundation 5.3.1Based on the site geological condition, the excavation of foundation trench shall be carried out in section by excavator and hydraulic hammer. When mechanical excavation reaches to 10cm above the designed foundation elevation, restart the survey and staking-out. And then the excavation of foundationshall be excavated and cleaned manually to ensure that the foundation complies with the design and specification requirements (bearing capacity of retaining wall foundation shall comply with the following requirements: 1. For the sandy soil and sand clay, the bearing capacity shall not be less than 250KPa. 2.For the softy rock, the bearing capacity shall not be less than 350KPa. 3. For the tough rock, the bearing capacity shall not be less than 500KPa. )5.3.2Pay close attention to slope stability during excavation. If there is any crack on the top surface soil of the pit edge, reliable support shall be provided immediately.5.3.3The slope rate offoundation trenchis determined by site geological condition and excavation depth, and there should be tilted with slope on foundation bottom, within the range of 0.2:1(slope rate can be properly lowered if rock layer and excavation depth is not deep), but the detailed condition shall be determined by drawing. Foundation excavation dimension is as following:Drawing B2 refers to the width of retaining wall foundation bottom, 1：n is representing excavation slope rate of foundation pit, and n is determined according to geological condition; gravel soil: n=0.75, yellow (clay) soil: n=0.5, rock n=0.3. 5.3.4When foundation pit excavation reaches to the designed elevation specified in the drawing, bearing capacity test should be conducted for foundation bottom. If it does not satisfies the design requirement, a foundation treatment plan shall be proposed in accordance with actual drilling (digging) and soil testing data, and submitted to CHEC Project for review, and revised accordingly as per his/her instruction. Without prior approval from CHEC Project, concrete casting or masonry work is not allowed for excavated foundation pit.5.4 Foundation Wall Casting5.4.1Conduct survey and staking-out shall be based on drawing, and then identify foundation dimension.5.4.2 Formwork Erection1) The steel formwork shall beadopted, and the formwork with parts missing or broken is prohibited using.2) Make sure the design, shape, dimension and mutual location of concrete structure and each part of components shall be correct.3) The formwork shall possess sufficient strength, rigidity and stability tostand the gravity and lateral pressure of newly-cast concrete as well as various possible loads arising during construction.4) There shall be no cement slurry leakage between formwork joints; contact surface between formwork and concrete shall be clean, and afterwards releasing agent shall be applied, which shall not affect the performance of formwork. The formwork shall be cleaned up and stored as per requirement after dismantling.5) The formwork adopts 50 rack pipes as horizontal band and vertical band, both spacing 50cm, the flank of formwork is fixed to the slope of foundation trench with adjustable top support, with support space 90cm. First assemble formwork in pieces, then assemble in section according to the location of settlement joint, after each section assembly, adjust formwork straight degree with lines on the four sides, fix it only after meeting the quality requirements. In order to ensure the internal width of formwork, wood support, having the same thickness with the wall, is set inside the formwork as internal support, a row of bolts penetrating the wall is set at the upper, middle, bottom, and one support is added to the upper of formwork for anchoring.5.4.3 Concrete Casting 1) The following preparation shall be made before casting concrete:Prior to concrete cast, fix formwork, level and tighten joints, clean debris, and discharge ponding water.2)The slump degree of concrete sent to site shall be tested from time to time, for those not meeting the requirements shall be returned to the batching plant for reprocess, and adding water randomly is prohibited.3) The concrete shall be cast in layer, with thickness not exceeding 1m, and the construction joint shall bot be randomly leaved. 4)Concrete placement shall be conducted continuously. When it stops due to certain reasons, the interval shall be less than selling time or reshaping time of previous layer concrete.When dumping concrete from higher location, the following requirements shall be satisfied in order to prevent concrete separation: the height shall be controlled within 2m; if the height is over 2m, a conduit or chute shall be put into use.During concrete cast, concrete shall be vibrated from time to time to make it uniformly dense, and vibration is recommended to be carried out vertically by immersion vibrator. Fast insertion and slow withdraw shall execute during vibration. Seamless vibration and non-defects on the concrete surface are recommended.The rubble placed into concrete in the rubble concrete retaining wall shall satisfy the following requirements:（1）Rubble intensity level shall not be less than 30Mpa.（2）Maximum size for rubble stone shall not be more than 1/4 of its depth of the layer, and the minimum size of the rubble stone shall not be less than 15cm.（3）Rubble shall be washed clean before placing.（4）Rubble shall be placed evenly and securely, net distance between rubble shall not be less than 15cm, not less than 25cm between rubble and formwork.（5）The top surface of uppermost rubble shall be covered by concrete layer, with thickness not less than 25cm.（6）Rubble shall be placed manually, and special attention must be paid to rubble so as not to damage formwork and PVC pipe.（7）The volume of rubble shall not exceed 25% of the total volume of rubble concrete.8) After concrete cast completion; cover it with geotechnical fabric for curing, whose duration will not be less than 7 days.5.4.4 Construction Joints Treatment1）Stalagmite shall be placed at each construction joint, to enhance concrete adhesion capacity.2）Artificialchiseling shall be carried out at the smooth spot of construction joint, chiseling area greater than 80% of the total area.5.5 Wall Backfilling and Weep Hole and Settlement Joint Arrangement5.5.1 Clay shall be used for backfilling under the outlet of each layer, 15cm deep for each layer and 30cm high in all, and then tamped manually. One layer of 30cm natural gravel filter layer is filled into retaining wall back, the content of natural gravel 5%.5.5.2 When intensity of wall concrete reach more than 70% of the designed intensity, backfilling for retaining wall back shall be conducted to ensure the quality of wall.5.5.3 Wall backfilling shall be conducted and tamped in layer by 15cm. For the part which cant be tamped by roller, artificial electric tamping compaction is recommended.5.5.4 For the wall above ground, outlet shall be set alternately each 2m. The outlet entrances location shall be strictly controlled to ensure that their location is accurate, in straight lines. 50mm PVC pipe shall be embedded into the outlet and extended to 10cm deep of wall back, and geo-textile shall be used for packing at the ends 20cm point. The bottom of outlet shall be 30cm higher than the ground, and permeable geo-textile shall be applied to the inlet. At the same time, control water slope of the outlet at 4% during construction, ensuring smooth drainage of the outlet.5.5.5 One settlement joint shall be provided at each 10-15m interval, with 2cm wide gap. And the gap shall be filled by asphalt oakum, 15cm deep.5.5.6 The material shall be compacted after the excavation of retaining wall completed, and which surface shall be covered by M7.5，thickness 30cm and width 3m rubble stone.6 QUALITY TESTING STANDARD6.1 Visually Testing and Acceptable ToleranceGuide Specifications for Highway Construction, 9th Edition DIVISION 700 MATERIAL REQUIREMENTSGuide Specifications for Highway Construction, 9th Edition SECTION 801 EXCAVATION AND BACKFILL FOR MAJOR STRUCTURESGuide Specifications for Highway Construction, 9th Edition SECTION 808 CONCRETE STRUCTURESGuide Specifications for Highway Construction, 9th EditionSECTION 809 REINFORCING STEEL6.2 Testing FrequencyGuide Specifications for Highway Construction, 9th Edition DIVISION 700MATERIAL REQUIREMENTSGuide Specifications for Highway Construction, 9th EditionSECTION 801 EXCAVATION AND BACKFILL FOR MAJOR STRUCTURESGuide Specifications for Highway Construction, 9th EditionSECTION 808 CONCRETE STRUCTURESGuide Specifications for Highway Construction, 9th EditionSECTION 809 REINFORCING STEELInspection Test Plans（ITP）Attached listconcrete retaining wallinspection itemNo.Inspection ItemtoleranceTesting method and frequencyremark1Subgrade bearing capacityComply with design standardpenetrometer：every section2Strength of concrete(MPa)Strength of sample3Plan location(mm)Within the qualified standardTotal station instrument: 3 spot for each 20m4Elevation of top surface(mm)20Level instrument: 1 spot for each 20m5Verticality (%)0.3Hanging vertical line：2 spot for each 20m6Dimension of cross section(mm)Not less than design standardTape measure：inspect 2 section for each 20m，selective test 2 counterfort7Elevation of bottom (mm)30Level instrument: 1 spot for each 20m8Surface evenness(mm)52m straightedge ：2 spot for each 20m7 ENVIRONMENT AND SAFETYPage 14 of 19APPENDIX AENVIRONMENTAL RISK ASSESSMENT Page 18 of 19 NATURE OF RISK ASSESSMENT: Concrete Retaining WallREFERENCEPOTENTIAL HAZARDPOTENTIAL CONSEQUENCESCONTROL MEASURESWORK ACTIVITIES1.No intercepting drainage facility2.Damage to vegetation3.Waste water4.Fugitive dust5.Solid waste6.Noise7.Vibration8.Woodland occupancy1.Soil erosion, debris flow, landslide2.Soil erosion, debris flow, landslide3.River and underground water contamination4.Air pollution5.Environment pollution6.Damage to hearing , disturbance to community 7.Damage to building , disturbance to community8.Soil erosion1.Provide intercepting drainage facility before and during construction2. Provide intercepting drainage facility before and during construction, and restore vegetation after completion.3.Discharge waste water after its disposal4.Sprinkle and cover5.Gather collectively6. Operator wears earplug to protect hearing; arrange noise work in a specific period.7.Provide earthquake-proof zone, work in a specific period8.Provide intercepting drainage facilityEQUIPMENT CLEANING1. Chemical waste1. Contamination of ground & water1.Ensure equipment is only washed at the designated location in the site yard to ensure chemical waste is collected by the interceptorGENERAL ACTIVITIES1. Waste (se