Method statement of removal existing bridge ( Thuyết minh biện pháp thi công phá dỡ cầu hiện trạng)

Biện pháp mô tả chi tiết quy trình phá rỡ Cầu hiện trạng, phục vụ công tác chuẩn bị thi công Cầu mới. Biện pháp được biên soạn dựa trên các chỉ dẫn kỹ thuật dự án.

7.2Removal of Wood deck slabs, Longitudinal Steel Beam 8

7.3Removal of Horizontal Beam, Truss Bailey 9

7.4Removal of Structure of Bridge Pier 9

7.5Removal of Structure of Abutment 9

7 TRAFFIC SAFETY CONTROL 10

7.1Traffic Closing Basis 10

7.2Site Layout 10

7.3Traffic Control of Blocked Sections 10

8. ENVIROMENT AND SAFETY CONTROL 10

8.1Safety Control 10

8.2Environmental Control 11

9 APPENDIX 12

1.GENERAL DESCRIPTION1.1 Introduction

This method statement provides the details of the procedure, the manpower, the equipment andrelevant documents related to removal works of Existing Bridge, including the quality controlverifications, the measurement verifications, and also the safety precautions and environmentprotection to be implemented for this work

1.2 Project Information

The project road connects Tbong Khmum district to Kratie province of the Cambodia, stretching alongthe northern, to Kratie province The road passes on a comfortable alignment through flat/wavy terrainalong the toe of hilly land Four (4) rather sharp curves along the road are considered non-critical dueto adequate super-elevation of the road way and appropriate signage The traffic on the road is amedium mix of private cars and quite heavy trucks that contribute mainly to the road wear ThePR.377 and PR377A of RCIP are located in Kratie province The length of the PR377 is 35.00 km andthe PR377A is 13.593km The location of the packages is shown in Figure-1

Figure 1.2 Location of Contract Package on CW-3(PR377 & PR377A)

1.3 Project Objective

The objective of the project is to ensure continued effective use of the rehabilitated national andprovincial road network in support of the economic development in Cambodia It will do so byimproving the institutional and technical capacity of the Ministry of Public Works and Transport forroad maintenance planning, budgeting and operations as well as by expanding of strengtheningmaintenance activities

The project seeks to contribute to cultivating a road asset management culture within the sector by:(i) expanding maintenance of the national road infrastructure nationwide and facilitating interventionsin priority areas, (ii) allocating adequate maintenance funding during the budgeting process; (iii).knowledge building in MPWT on road network management, maintenance technology and contractmanagement; and (iv) private sector involvement in competitive bidding and performance quality.Project is expected to bring significant benefits to local residents in six Cambodian provinces,Kampong chham, Tbong Phmum, Kratie, Mondulkiri, Ratanakiri and Stung treng province; byreduced travel times and cost, less arduous journeys and better connectivity along the national roadnetwork It is intended that the benefits to local populations are maximized, and to ensure that thebenefits are shared by local communities.

1.4 Topography and Climate

The topography in the project area is mainly flat with some hilly sections and the road elevation variesfrom minimum 23.52m to maximum 50.95meter The maximum temperature is around 40°C, theannual temperature fluctuates more than 10°C and from 6 – 7°C in a day In hot weather the absolutehigh temperature may be up to 39°C (in April) By contrast, in January the absolute low temperaturemay descend to 16°C

1.5 Rainfall Records

The available hydrometeorological data such as rainfall are obtained from the Kratie ProvincialDepartment of Water Resources and Meteorology (PDoWRAM) The rainfall station is located at(X=610976, Y=1379728) The data ranged from 1980 to 2019 is considered to conduct frequencyanalysis for hydrologic modeling The 24hr maximum annual rainfall over 3 decades were extractedfor the analysis as shown in Figure 4.1 and 4.2 below From the figure below, it’s clearly observed thatthe highest rainfall over the period was in the year of 1988 with a value above 250mm, followed by theyear of 1982 as the second highest with the precipitation of above 270mm The year 2009 is observedto have above 150mm which was the highest rate over the 10 year after 1992 and it was revealedduring the Ketsana storm In 2001 was noted as lowest rainfall, it’s reflected to the Droughtperiod

Figure 1.5.1 Daily Rainfall Ditribution in Kratie 1980-2019

Figure 1.5.2 Rainfall Distribution over 1980-2019

Length(m)

Width

02

PK1+763.00

03

PK9+793.50

04

PK15+221.00

PK20+125.00

06

PK22+307.06

side

07

PK23+673.00

side

09

PK26+395.00

side

11

PK30+920.50

12

PK31+868.00

2.2Standards and Technical specification related

+ Section 2.1: Clearing and Grubbing+ Section 2.7: Removal of Existing Structure

2.3Construction Schedule

Construction Schedule shall be referred to latest approved Schedule

Organization Chart is as follow:

POLY CHANDA ENGINEERING CO., LTD

PROJECT MANAGER

Mr.WEI JAING

Material Engineer

Mr LAI DE SEN

AMP Manager

Mr.LIN ZHI HUI

Design Engineer

Mr LAI DUY TRUNG

QA/QCManager

Mr XU CHENG HUI

Safety & EnvironmentalManager

Mr LIN JIN HAO

For the removal of existing Bridge, the Contractor will divide into the construction sections, eachconstruction section will be mobilized personnel and equipment as described following

Equipments proposed as in Table below (they all have verification certificates of safety):

Note: This equipment will be increased according to the site requirements

Manpower to be mobilized for construction work as below:

4 Drivers for Excavator 1

 If the superstructure or any portion of the structure is deemed fit for use elsewhere, the useableportions shall be marked and removed without damage

 When the Drawings provide for using the existing substructures, or part of same, as permanent parts ofthe new structure, only those portions indicated on the Drawings to be removed shall be removed.When no such use is contemplated, all exposed portions of the existing structures above the stream bedshall be completely removed When the proposed structure is a bridge, and it becomes necessary toremove the portions of the existing structure below ground in order to construct the new work, suchremoval will be classed as excavation as provided for in Section 2.5 Excavation and Backfill forStructures

7.1Preparation Works

 Mobilization of equipment, machinery and human resources Gathering other materials related to the demolition work The site should be prepared The contractor will contact the local electricity bureau, water supply plant

and communication company in advance to remove above and below ground pipelines, equipmentfoundations and other obstacles in the construction area

 Prior to the demolition of the bridge, all pipelines in the vicinity of the bridge should be relocated to asafe location The traffic flow should be directed to the access road and bridge in an orderly manner,and the construction platform should be filled in on the construction side of the bridge to make it level. During the construction of removal existing structure, traffic will be maintained on the temporarybridge The contractor will install protective fences, sign systems, night lights and workers to guidetraffic on both sides of the bridge

 Temporary road for construction will be established, serving the process of removing existing bridgeitems as well as constructing new bridge items

7.2Removal of Wood deck slabs, Longitudinal Steel Beam

steel connecting the wooden slab with the longitudinal beam and the longitudinal beam with thehorizontal beam

 Workers after cutting the link steels will proceed to remove the deck boards The wooden panels aremanually transported out of the original position, then the steel longitudinal beams will be taken outfrom the original position by the crane device and gathered at the specified position

 In case the steel railing on the steel bridge is a linked steel bar system: Use appropriate tools to cut andremove the steel railing.

 The removed components are neatly collected and transported to the designated place by truck

7.3Removal of Horizontal Beam, Truss Bailey

 After dismantling the bridge deck and longitudinal beams, using workers in combination with oxygenequipment to cut the connections between the horizontal beams and the bailey steel truss

 Using a 50T crane standing on the temporary road to hoist the steel beams down to the designatedplace

 Complete dismantling of cross beam, continue dismantling and hoisting bailey steel truss fromconstruction span

 In the process of dismantling the existing structure, the contractor must always pay attention to andensure the safety of people and equipment

 The remaining spans are constructed similarly to the previous span

7.4Removal of Structure of Bridge Pier

 Demolition of pier column:In case of cylindrical body made of linked steel system:

+ Using workers combined with oxygen equipment to cut the steel system between the steel pillars.+ After completing step 1, use the crane to pull up the steel pile and transport it to the specifiedlocation

In case of wooden body:

+ Dismantle the ties between the wooden pillars together.+ Use a cable to fasten to the body of the wooden pillar, then use the crane to lift it from the originalposition and gather at the specified position

 Demolition of reinforced concrete pier foundation:

+ Using concrete breakers in combination with workers to demolish reinforced concrete structures.+ Using excavators to dredge waste materials and mud around the foundation to the demolition height.+ Use a specialized concrete breaker to knock down the foundation concrete block to the demolitionlevel, then use a crane to collect the destroyed concrete blocks and transport them to the specifiedplace

+ In the case that the reinforced concrete pile foundation is under the foundation, after handling thereinforced concrete foundation, use specialized equipment to lift the reinforced concrete pile at thebottom of the foundation off the ground

+ The demolition process is completed, the Contractor uses an excavator to excavate the scatteredmaterials into the river bed according to regulations

7.5Removal of Structure of Abutment

 Use an excavator to dig around the abutment to the height to be demolished

workers. For reinforced concrete structures: Use a concrete breaker to break the protective concrete layer,

then workers use oxygen to cut the steel bars in the structure. Use a crane to lifting concrete blocks and transport them to the specified place

 Construction of concrete destruction layer by layer to the required demolition height. For abutment structures made of assembled gabions: Proceed to cut the gabions, Use an excavator

in combination with labor to take the stone mixture out of position and transport it to the specifiedplace

 For bridge abutments that are steel or wooden piers, the removal of the structure is similar tothe steps mentioned above.

Note: During the construction and demolition of the old bridge, the contractor uses shielding methods

combined with water spray to avoid dust from the demolition work from affecting the environmentaround the construction area

7.1Traffic Closing Basis

 The lanes shall be closed to execute, traffic will be maintained and guaranteed on the detour road Thedetour road shall be design based on the principles of facilitating the construction vehicles to enter orleave the site and the passing vehicles to pass smoothly

7.2Site Layout

 The lanes shall be closed to execute, traffic will be maintained and guaranteed on the detour road

7.3Traffic Control of Blocked Sections

 For construction personnel in accordance with the safety regulations for construction. No drinking, slippers, and sandals are allowed on site

 The insurance fee shall be paid on time and warning flashlights be installed for the constructionvehicles

 The traffic rules shall be com plied with and no parking on the lane or turning around randomly bepermitted for construction vehicles

 The finished sections shall be protected carefully, and roadblocks or warning signs shall be placed ifnecessary

 The damaged safety signs which affect the expression of the safety information shall be replaced intime

 Safety signs shall be placed in bright environment and at a proper distance from the danger location sothat the relevant people have enough time to note the information that it represents

 The safety signs with dirt, grease shall be cleaned timely to ensure the safety information without themistakable messages

 The safety signs with displacement shall be adjusted in place to avoid accidents, which result from therelevant people's not quickly noticing and understanding the safety information

8.1Safety Control

Prior to starting of construction works, warning signs and instruction boards shall be fully installedeither inside or surrounding the construction site and the following particular matters are to be throughto all members working in the construction site in order to complete the work efficiently without anyaccident or casualty

a) Joint Meeting

 Prior to start any activity, a joint meeting with relevant staffs shall be held for the purpose of generalexplanation on the whole contents of works as well as the method for the implementation of efficientwork.

b) Basic Instruction

 All workers shall always wear Personal Protective Equipment (PPE), such as hardhat (helmet), safetyshoes, hand gloves and working uniform

c) Prevention of Accident by Heavy Machine

 Only skilled operator shall be allowed to operate equipment on site In case of new operators, a test ofskill shall be conducted first prior to his acceptance to the job Preventive maintenance check shall bedone regularly at equipment working at site prior to full operation Stability of working area andfoundation of equipment shall be checked particularly at locations of outrigger and track pad of cranes

d) Prevention of Accident of Electrocution

 Electric generating equipment shall be properly protected and properly installed with earth connection.Electric wires shall relate to electrical tapes to prevent electric leakage Only skilled operator shall beallowed to operate equipment on site

e) Prevention of Accident in Night Shift Works

 Enough lighting system shall be provided for night shift works especially installed at workingplatforms If necessary, all the surrounding working area shall be lighted up The people who work onthe site must wear reflective jacket, if worked at night

a) Ambient air quality

 Exhaust emissions from construction equipment shall be strictly controlled in accordance TheContractors are requested to use standard equipment

 Where possible the Contractor ’s chosen access routes to and from the site should avoid residentialareas Vehicles carrying sand, aggregates or other loose materials shall be fully covered Brushing andwatering shall be used where required to control dust and the spraying of mud

 Stockpiles should be covered or kept damp to avoid windblown dust