PIPE JACKING 1 Internet Document Pipe Jacking – Ritchie-Wiki . Available online at http://www.ritchiewiki.com/wiki/index.php/Pipe_Jacking, checked on 2/4/2017 . Internet Document Pipe Jacking Association Homepage. Available online at http://pipejacking.org/, checked on 2/8/2017 . Internet Document Welcome to Civil and Environmental Engineering at the University of Waterloo. Available online at https://uwaterloo.ca/civil-environmental-engineering/, checked on 2/8/2017 . Internet Document Ongoing & Upcoming Trenchless Projects in India (2016). Available online at http://www.indstt.com/trenchless_projects.html, updated on 12/17/2016, checked on 2/8/2017. Reference:
CONTENTS Introduction Brief History Methodology Application Standards Equipment/Component Classification Alternative methods Pros & Cons 2
INTRODUCTION Pipe Jacking is the oldest method of trenchless technology. Pipes are pushed through the ground behind the shield using powerful jacks. Simultaneously excavation takes place within the shield. This process is continued until the pipeline is completed. The method provides a flexible, structural, watertight, finished pipeline as the tunnel is excavated . Thrust wall is provided for the reaction of the jacks. 3
Contd. 4 Figure 1: Pipe jacking process (a) Jacks are pushing pipe (b) Installation of pipeline under a runway. (a) (b) Source: www.pipejacking.org Source: www.pipejacking.org
CONTENTS Introduction Brief History Methodology Application Standards Equipment/Component Classification Alternative methods Pros & Cons 5
BRIEF HISTORY First mentioned in 1910, USA by Richardson & Mayo. In 60s, used in UK and APJA(American Pipe Jacking Association) is formed. In 70s, process is industrialized in Japan. In 80s, developed in Europe. ( i ) 1800mm dia trenchless pipe is laid for 460m in London,1982 . (ii ) 560m in water bearing sand and gravel, Byles, 1983. Komatsu introduced first fully automated machine in 1975 – IRONMOLE Today pipe jacking is remotely operated. 6
INDIAN HISTORY First project is of 3.5km in 1998, Mumbai. In Cuttack 10km is constructed for sewer using trenchless method. Other projects of less than 8km is completed in Goa, Hyderabad, Kolkata, Delhi, Assam etc. A total of around 100km is build so far using trenchless methods so far. Ongoing projects- 55km of interceptor sewer along 3 major drains for reduction of pollution in Yamuna river at New Delhi. 7
CONTENTS Introduction Brief History Methodology Application Standards Equipment /Component Classification Alternative methods Pros & Cons 8
METHODOLOGY 9
PLANING Understand the site history and potential obstructions. Look at old aerial photos. Conduct a geotechnical program. Locate all existing utilities. Minimize costs. Develop the best cross section. Use the right materials. 10
PROCEDURE The thrust pit and the reception pit are excavated at the required places. Then the thrust wall is set up in the thrust pit according to the requirement. In case of mechanized excavations, a very large pit is required. But in case of manual excavation, a small pit is enough. Thrust ring is provided to ensure the even distribution of stress along the circumference of the pipe. 11
Contd. The number of jacks vary upon the frictional resistance of the soil, strength of pipes etc., The size of the reception pit is to be big enough to receive the jacking shield. To maintain the accuracy of alignment a steerable shield is used during the pipe jacking. In case of small and short distance excavations, ordinary survey method is sufficient. But in case of long excavations, remote sensing and other techniques can be used. 12
SPECIFIC FEATURES Simple cyclic procedure. Utilizes thrust from hydraulic jacks to force the pipe forward Person have to enter in pipe for excavation. Excavation can be manual or by machine. Excavation takes place in front of an articulated shield. > Designed for worker safety. > Shield guided with individually controlled hydraulic jacks. Practically limited to dia. g reater than or equal to 1075mm. Pipe installation process occurs from entrance and exit shaft. 15
PROCESS BASED ON SOIL Unstable soil Face excavated simultaneously with the jacking operation. Minimize over excavation and the risk of face collapse. After pipe jacked into place hydraulic rams are retracted and another pipe length is installed. Stable soil Face excavation may precede the jacking operation. All spoils removed through the inside of the pipe to the jacking pit. 17
PIPE JACKING FORCE Force on jacked pipe includes : > Pipe dead weight. > Penetration resistance or face pressure. > Soil-pipe friction. Other forces like: > Curvature forces. > Soil dead load. > Railway or highway live load. Jacking force must not exceed allowable pipe compressive strength . 18
19 Figure 4: Face Resistance Source: www.youtube.com
20 Figure 5: Skin friction and face resistance Source: www.youtube.com
21 Figure 6: Total force is greater than permissible limit Source: www.youtube.com
22 Figure 7: Force distribution with intermediate jack Intermediate jack Source: www.youtube.com
FAILURE Pipe generally fails from the corner first. Maximum force is acting at the edges due to: > Uneven distribution of jacking force from one pipe to another. > Unavoidable curvature. > Elastic forces from pressure transfer rings at joints. 23 Figure 8: Failure of pipe Source: www.youtube.com Source: www.youtube.com
24 Figure 9: Failure of pipe Source: www.youtube.com
POSSIBLE SOLUTION 25
CONTENTS Introduction Brief History Methodology Application Standards Equipment/Component Classification Alternative methods Pros & Cons 26
APPLICATION Larger Diameter Pipe (1050 mm and up ). Lengths can range from 3 to over 200m. Sewers, and drainage construction. Gas and water mains. Oil pipelines. Industrial pipelines. Telecommunication. Pedestrian subways (access tunnels ). 27
CONTENTS Introduction Brief History Methodology Application Standards Equipment/Component Classification Alternative methods Pros & Cons 28
STANDARDS 29 BS 6164: 2011 – Code of practice for health and safety in tunnelling in the construction industry. BS EN 16191 – Tunnelling machinery safety requirements Table 1: Standards for pipe jacking Source: www.pipejacking.org
CONTENTS Introduction Brief History Methodology Application Standards Equipment/Component Classification Alternative methods Pros & Cons 30
EQUIPMENT/COMPONENT Jacking Pit. Jack. Pipe . Thrust Ring. Thrust wall. Lubricant. Intermediate Jack. Cutting-head. Pressure Transfer Ring etc. 31
JACKING PIT 32 Jacking pit size is function of Length of pipe segments, Pipe diameter, Shield dimensions, Thrust wall design, Jack size, Pressure rings and Guide rail systems. Pit should be shored using Timber or steel piling. Placement of concrete slab on the floor is recommended. (a) (b) Figure 10: Typical Jacking Pit(a) and (b) Source: www.civil.uwaterloo.ca Source: www.civil.uwaterloo.ca
JACK AND PIPE Number and capacity of jack is a function of pipe size, length, skin friction, intermediate jacks etc. It is suggested to provide even number of jacks. Pipe should be light weighted, smooth and strong enough to withstand all the forces . 33 Figure 11a: Jack Figure 11b: RCP Pipe Source: www.civil.uwaterloo.ca Source: www.civil.uwaterloo.ca
THRUST RING AND THRUST WALL Thrust ring distributes force from jack head to pipe edges equally . A spacer is optional. Thrust wall is provided behind the jack to transfer back thrust of jack to earth and preventing jack to sink. 34 Figure 12a: Thrust Ring Figure 12b: Thrust Wall Source: www.google.com Source: www.google.com
LUBRICANT AND INTERMEDIATE JACK Lubrication is provided at outer edges of pipe using lubricant injection ports at proper interval. Intermediate jack is provided in between the entry and exit shaft. Number of intermediate jack depend on pipe length and jack capacity. IJ must match pipe diameter. 35 Figure 13a: Lubricant injection port Figure 13b: Intermediate Jack Source: www.civil.uwaterloo.ca Source: www.civil.uwaterloo.ca
CUTTING-HEAD AND PRESSURE TRANSFER RING Cutting-head or cutter is located at the front of pipe line. It cuts down the soil ahead using mechanical motion into smaller fragments. Pressure transfer ring is used in between of two pipe at joints, it distribute the pressure to succeeding pipe equally. It is made either of cork or synthetic material. 36 Figure 14b: Pressure Transfer Ring Figure 14a: Cutter-head Source: www.youtube.com Source: www.google.com
CONTENTS Introduction Brief History Methodology Application Standards Equipment/Component Classification Alternative methods Pros & Cons 37
CLASSIFICATION 38
39 (a) Reinforced Concrete (b) Vitrified C lay (c) Ductile Iron (d) Fibreglass (e) Steel (f) Composite Figure 15: Classification on basis of pipe material(a)-(f) Source: www.civil.uwaterloo.ca Source: www.civil.uwaterloo.ca Source: www.google.com Source: www.google.com Source: www.hobas.com Source: www.google.com
40 (d) Backacters (a) Open Face Cutter Booms (e) Pressurized Slurry (b) Tunnel Boring Machine (c) Earth P ressure Balance Figure 16: Classification on basis of Cutter-head(a)-(e) Source: http :// rightofway.transportation.org Source: http :// rightofway.transportation.org Source: http :// rightofway.transportation.org Source: http :// rightofway.transportation.org Source: http :// rightofway.transportation.org
41 (a) Manual Excavation (b) Machine Excavation (c) Conveyer belt Excavation (d) Slurry Excavation Figure 17: Classification on basis of excavation technique(a)-(d) Source: www.civil.uwaterloo.ca Source: www.civil.uwaterloo.ca Source: www.google.com Source: www.google.com
CONTENTS Introduction Brief History Methodology Application Standards Equipment /Component Classification Alternative methods Pros & Cons 42
CONTENTS Introduction Brief History Methodology Application Standards Equipment /Component Classification Alternative methods Pros & Cons 46
ADVANTAGE It avoids the excavation of trenches . Quick set-up, t imely finish of projects . Good quality control and good grade of pipe used. Can be remotely operated. Versatile in various ground conditions. Cost efficient for large length pipe. Small surface settlements. Reduces disruption to existing services. Environment friendly. Less spoil. 47
DISADVANTAGE Costly for small lengths. Skilled personal is required. Dewatering of tunnel path is usually required. Not feasible for nature of soil changes drastically. Hard rock/Bed rock or very big boulders should not be present in the path line. 48
CLOSING THOUGHTS Methods still evolving. Many hybrid methods emerging. Will never replace traditional open-cut methods; however, they complement each other. New idea To identify potential obstructions we can install a GPR(Ground Penetrating Radar) at cutting head. 49