CONSTRUCTION MEASURES OF SURROUND DRILLING 04 CW DN2600 PIPELINES

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Drilling underground jacking 04 lines of reinforced steel pipes DN2800 and pulling construction of 04 lines of CW DN2600 pipelines.

CONSTRUCTION MEASURES OF SURROUND DRILLING 04 CW DN2600 PIPELINES

TABLE OF CONTENTS

1. GENERAL INTRODUCTION 3

1.1. PROJECT OVERVIEW 3

1.2. DOCUMENTATION PURPOSE 3

1.3. LEGAL DOCUMENTS 3

1.4. DEFINITIONS AND Acronyms 3

2. PREPARATION OF CONSTRUCTION 4

3. CONSTRUCTION HUMAN RESOURCES 4

4. CONSTRUCTION EQUIPMENT 5

5. TEMPORARY WORKS FOR CONSTRUCTION 6

6. DRILLING CONSTRUCTION PROGRESS 7

7. CONSTRUCTION MATERIALS 7

8. DEVELOPMENT, DISTANCE TO US SURFACE CONSTRUCTIONS 7

9. CONSTRUCTION METHODS 7

9.1. SURVEY 7

9.2. MOBILE MACHINERY, EQUIPMENT AND HUMAN RESOURCES 8

9.3. ROAD SURFACE OF DRILLING AREA 8

9.4. PREPARATION OF DRILLING WORK 8

9.8. CW DN2600 TUBE PULLING WORK 12

9.9. CLEANING AND REFUNDING WORK 14

10. MEASURES Environmental sanitation, fire prevention and SITE SECURITY

10.1. GENERAL RULES 14

10.2. SECURUTY15

10.3. ENVIRONMENTAL SANITATION 15

10.4. FIRE FIGHTING, INTERNAL TRAFFIC SAFETY 15

10.5. WORKER SAFETY 17

1. GENERAL INTRODUCTION

1.1 PROJECT OVERVIEW

Name of the project: Drilling underground jacking 04 lines of reinforced steel pipes DN2800 and pulling construction of 04 lines of CW DN2600 pipelines.

Belonging to the project: Vung Ang II Thermal Power Plant

Type of project, grade of work: Group B projects, Water pipeline works, Grade II.

Location: Ky Anh district, Ha Tinh province.

1.2 DOCUMENTATION PURPOSE

The purpose of this document is to provide a method for the Contractor to implement and control the construction of 4 underground CW DN2600 pipelines across the road.

1.3 LEGAL DOCUMENTS

Construction Law No. 50/2014/QH 13 dated June 18, 2014 of the 13th National Assembly, 7th session;

Law on Environmental Protection No. 72/2020/QH14 passed on January 17, 2020 by the 14th National Assembly;

Decree No. 15/2021/ND-CP dated March 3, 2021 of the Government detailing a number of contents on construction investment project management;

Decree No. 06/2021/ND-CP dated January 26, 2021 of the Government detailing a number of contents on quality management, construction and maintenance of construction works;

Decree No. 11/2010/ND-CP dated February 24, 2010 of the Government providing for the management and protection of road traffic infrastructure;

Circular No. 50/2015/TT-BGTVT dated September 23, 2015 of the Ministry of Transport on "Guiding the implementation of a number of articles of Decree No. 11/2010/ND-CP dated February 24, 2010.

1.4 DEFINITIONS AND ACRONYMS

Investor	Vung Ang II Thermal Power Company Limited
Project	Vung Ang II Thermal Power Plant
Contractors	DHI-SCT . Joint Venture
Package	Design, Fabrication and Construction, Installation

HSE : Health, Safety and Environment

BDA : Project department

CBAT : Safety Officer

CBKT : Technical staff

MMTB : Devices

HT : System

2. PREPARATION OF CONSTRUCTION

The preparation work has been carried out according to the construction item of the whole pipeline.

3. CONSTRUCTION HUMAN RESOURCES

List of personnel participating in underground drilling

No.	First and last name	Date of birth	Identity card number	Home town	Work
1	Nguyen Van Thanh	6/5/1970	038070006601	Thanh Hoa	Director
2	Tran Anh Tuan	13/06/1972	273136899	Ha Tinh	Deputy commander
3	Đang Xuan Dien	7/10/1961	024716077	Nghe An	Deputy commander
4	Đang Minh Nhut	1986	025748413	Đong Thap	Deputy commander
5	Đo Thi Kim My	17/05/1997	291141831	Tay Ninh	Secretary
6	Nguyen Ngoc Thanh	20/03/1992	173754257	Thanh Hoa	Captain
7	Nguyen Tien Long	27/06/1998	175023765	Thanh Hoa	Technical staff
8	Tran Manh Sung	30/09/1976	033076001982	Hung Yen	Drilling machine driver
9	Au Le Hai	1973	312381178	Bac Giang	Drilling machine driver
10	Duong Van Minh	19/04/1987	281286071	Nghe An	Drilling Assistant
11	Nguyen Thanh Hung	03/09/1972	038072003565	Thanh Hoa	Drilling Assistant
12	Nguyen Van Sang	12/081968	261623922	Thai Nguyen	Drilling Assistant
13	Vo Xuan Oanh	30/10/1965	181484282	Nghe An	Drilling Assistant
14	Đoan Van Dong	1/12/1996	251064894	Lam Đong	Drilling Assistant
15	Duong Van Dai	10/10/1999	187766885	Nghe An	Drilling Assistant
16	Nguyen Ngoc Noi	20/11/1970	172156753	Thanh Hoa	Drilling Assistant
17	Phan Van Truc	20/03/1977	261221690	Thai Nguyen	Drilling Assistant
18	Pham Minh Tuan	19/05/1976	320940871	Ben Tre	Technical staff
19	Đao Minh Tuan	29/08/1995	362427232	Can Tho	Technical staff
20	Nguyen Minh Phung	09/08/1995	301600511	Long An	Technical staff

4. CONSTRUCTION EQUIPMENT

List of construction machinery and equipment:

No.	Types of machinery and equipment	Amount	Own/Rent	Note
1	Crane 50 tons	01
2	Generator 20 kVA	01
3	Excavator 1 m3	02
4	Welding machine A300	5
5	Grinding and cutting machine Ø150	4
6	Oil air compressor (8m3/min)	01
7	Hand drill	04
8	Hole Drilling Machine	01
9	Pressure Compressor + Recorder	01
10	HDD underground pipe drilling machine	01		GS-700 -LS
11	Drilling fluid mixer 2000L	01
12	Drill head locator	01
13	Laser distance meter	01
14	Depth gauge	01
15	walkie talkie	03
16	Tank truck carrying clean water	01
17	Concrete tank truck	01
18	Ground-penetrating radar detector	01
19	Guide drill rod	20
20	Drill head and extension shallow drill head	07
21	Hoist 5-10 tons	01
22	Mother of pearl / lotus leaf pile driving machine	01

Technical parameters of drilling machine GS - 700 – LS:

No	Parameters	Value
1	Thrust force	700KN
2	Traction	1400KN
3	Torque	30000Nm
4	Engine power	199KW
5	Max drill diameter	1500mm
6	Maximum drilling length	900m

5. TEMPORARY WORKS FOR CONSTRUCTION

Minh Phuong will transport 01 10 ft container containing equipment, construction tools and other works located at the gathering yard in the construction area.

Office at the construction site:

Housing of officials/workers will be rented houses in construction areas about 6 km.

Use 20kVA generator power supply to weld pipes. Water source for drilling is provided by tank trucks and mobile water tanks.

6. DRILLING CONSTRUCTION PROGRESS

Construction progress is calculated from the date the Investor receives the construction approval permit.

7. CONSTRUCTION MATERIALS

The list of main materials for construction of 04 sections of underground pipelines across the road, each 39m long pipeline section includes the following:

No	Materials and equipment	Std	Facing	Sch	inch	Unit	Amount
1	CW pipe DN2600		BE	40		m	156
2	DN2800 reinforced steel pipe					m	156

8. DEVELOPMENT, DISTANCE TO US SURFACE CONSTRUCTIONS

The depth of burying pipes when crossing the road is determined based on API RP 1102, the input parameters are the wall thickness of the pipe, the depth of burying the pipe through the road, the parameters of the road and the operating vehicle. Test the stress in the pipe against the allowable stress and the fatigue of the weld against the fatigue limit of the weld to ensure that the pipe is not damaged or destroyed during operation.

9. CONSTRUCTION METHODS

9.1 SURVEY

Survey of construction layout

The construction team, the survey team discussed and calculated the actual characteristics of the ground, the existing obstacles if any (lines, underground cables, sewer pipes, ...), determined the location of drilling machines, welding nests. Combination of CW DN2600 pipe and welding of reinforced steel pipe, preparation for pulling, construction plan, gathering equipment and materials, possible obstacles and proposing solutions to speed up progress (if necessary).

Thus, it can be seen that the difficulties mainly stem from natural conditions: ground, geographical location, weather. To overcome these difficulties and speed up the progress, the contractor determined to follow the following criteria:

Optimal resource mobilization for all stages.

Reasonable arrangement of resources to coordinate smoothly between construction sites, with local authorities, functional agencies and the Investor without creating downtime during the construction process.

Strictly control, find potential risks, focus on handling immediately to prevent these potentials from developing into problems.

9.2 MOBILE MACHINERY, EQUIPMENT AND HUMAN RESOURCES

Based on survey data, Minh Phuong has selected suitable equipment and materials to gather to the project. The correct and sufficient selection ensures efficient construction, on schedule and minimizes the costs incurred.

Construction personnel to carry out the project must ensure that they have been trained in safety and have specialized certificates appropriate to the field in charge.

9.3 ROAD SURFACE OF DRILLING AREA

When starting underground drilling through the road, the construction unit will install a speed limit sign of 5 km/h.

Reinforce the roadbed by spreading 10mm thick steel plates on the road surface at the underground drilling site.

Appoint people to be on duty 24/24 h at the construction site to remind vehicles to limit speed when passing through the construction area.

The borehole is filled with betonite, after pulling the pipe, it is filled with low grade concrete or soil cement concrete to compensate for the empty hole in the pipe drilling process.

After pulling the pipe, the borehole part is reinforced with low grade concrete or soil cement concrete, which is fixed and kept stable after 72 hours before removing the reinforced corrugated iron layer on the road surface.

9.4 PREPARATION OF DRILLING WORK

Using an electronic total station to determine the scope of the construction site in the field.

Build 04 2600mm diameter pipelines, can change the number of pipes with 2 pipes (DN3700) at the detailed engineer stage.

Barriers, construction site signs

10. SURFACE DRILLING STAINLESS STEEL PIPE REINFORCED DN2800

High power hydraulic jacks are used to push special pipe joints into the ground with front mounted locomotives.

The construction of the drainage system by underground jacking technology is carried out through the following steps:

1. Survey the condition and condition of the ground before construction and measure and determine the construction location.

2. Construction of jacking wells and receiving wells.

- Jacking well: In order to be able to execute underground jacking drills and install pipes with a depth of 9.0m compared to the road surface, the minimum depth of construction pits is 9.5m deep. Dimensions of the excavated hole are: length=3.0m; width = 3.0m; depth=9.5m. The jack drill is placed at a height of +0m above the bottom of the jacking well. The jacking well is reinforced with Larsen piles to prevent landslides during the construction process.

- Receiving well: dug to a depth of 9.5m above the road surface. This well has the effect of opening the borehole, receiving the pipe and constructing the pipe winch to help orient the pipe. The cross-section of the receiving pit has the following area: length=3.0m; width = 3m; depth=9.5m. The well received reinforcement of Larsen piles to prevent landslides for the receiving well during the construction process.

3. Precise positioning of soft eye position at jack-well outlet and receiving-well inlet.

- Soft eye positioning is based on the design elevation of the bottom of the culvert.

4. Transporting construction equipment and tributes to the construction site.

- The sluice gates have a different structure from the open excavation culverts to be suitable for pipe jacking. There are 3 types of tributes:

+ Standard pipe: This culvert has a normal structure, only the position of a crane hook is used to lower the drain into the size of the pipe.

+ Grouting pipe (Grouting pipe): This sluice has the same structure as a regular culvert but has 3 additional holes located 120o apart along the circumference of the culvert to serve the pumping of Bentonite grout around the culvert wall.

+ Intermediate pipe: This is a pair of drains including male pipe (Male pipe) and female pipe (Female pipe). The intermediate jack is arranged between these two drains. After jacking the entire sewer line, the intermediate jack is dismantled and pushed together.

5. Installation of ground support equipment for jacking: Crane truck, sludge settling tank, dredger, generator, Bentonite pumping station.

- Bentonite pumping station has the purpose of pumping Bentonite mortar to the outside around the pipe body to reduce the friction between the soil and the pipe wall.

6. Installation of supporting equipment in the well for jacking: Mud pump system, ventilation system, control system, hydraulic system, electrical system, bentonite pumping system, laser guidance system , gasket to prevent water, jet wall.

7. Install the main jacking system and connect with supporting devices: Hydraulic jack, push jack ring: contact washer between drain and main jack, drill head, intermediate jack (if any).

8. Operate the jacking system to bring the drill head into the ground to start the pipe jacking work. Install successive culverts behind the drill head and intermediate jacking stations (if necessary) until the culvert and drill head enter the receiving well.

- During the pipe jacking process, it is necessary to monitor the main jacking force. If the main jacking force is too large, it can burst the drain, then it is necessary to install intermediate jacking stations to reduce the main jacking force.

- The positions of intermediate jacking stations are determined based on calculations.

9. At the location of the receiving well, install the receiving gasket, the jack receiving frame.

10. Transport the drill head and jacking aids in the tunnel out of the receiving well. Clean the construction site according to regulations.

Drilling technology

Drilling fluid used for pipe pulling work

Drilling fluid is an important component of successful pipe pulling. Basically, drilling fluid is a mixture of water, bentonite and additives. The amount of bentonite used is calculated based on the engineering geological parameters and the diameter and length of the borehole.

Drilling fluid has the following functions:

Breaking, mixing soil, rock, sand in the tunnel where the drill head and break head pass when being pumped and compressed with high pressure.

Establish and maintain tunnel stability (avoid tunnel collapse).

Lubricate the drill head, break head and drill rod, reducing heat concentration on these tools.

Transporting soil, rock, sand in the tunnel to the outside.

Another important property of drilling fluid is that it can be reused through the use of recycling equipment.

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