Tunnel segment bolt

Tunnel Shield Bolt for Sale

Tunnel Segment Bolt Details

  • Standard: According to drawing requirement
  • Raw Material: Q235, 45#
  • Strength Level: 5.6, 6.8, 8.8
  • Surface Treatment: sherardizing, dacromet, hot-dip galvanizing.
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Tunnel Segment Bolt Introduction

Shield segment bolts are special fasteners used to fasten or connect segments during the construction of shield tunneling machines. Several arched segments are connected by segment bolts to form a circle, and the entire tunnel surface is supported by this circle, so it is also called segment connector. Because it is specially used for shield tunnels, it is also called shield segment bolts or tunnel connectors. Shield machines are usually used in tunnel excavation. Tunnel transportation of soil and slag, and excavation and cutting of soil are inseparable from shield machines. Shield machines are usually composed of multiple segments, which are composed of pipes. Tunnel segment bolts are connected and tightened to form a cylindrical pipe, then the segment becomes the pipe wall, and the linear or arc-shaped fasteners are tunnel segment bolts. Tunnel segment bolts vary according to the shield diameter. Different sizes of segments have various designs and types. Tunnel segment bolts can also be called segment connectors. Commonly used surface treatments are: hot-dip galvanizing, sherardizing, dacromet, etc.

subway tunnel construction
tunnel shiled segment bolt stock
Subway Tunnel Project

Shield Tunneling Method

The shield tunneling method is a construction method of digging tunnels under the ground. It has been widely used in Subway Line, railway, highway, municipal, hydropower and other tunnel projects. During the construction, in order to prevent the collapse of the soft foundation excavation surface or maintain the stability of the excavation surface when the shield machine is used for underground excavation, it is necessary to carry out lining operations in the tunnel at the same time, and lining prefabricated segments are reinforced with tunnel segment bolts. Due to the different pressures exerted on the shield by different geological conditions, the design mechanical properties of the shield segment bolts are more than 5.8, 6.8, 8.8, and 10.9.

Tunnel Segment Bolt Types

Usually tunnel segment bolts are divided into 6 types, namely: hexagonal head arc segment bolts, non-standard segment bolts, double-ended straight segment bolts, double-ended arc segment bolts, hexagonal flange face circle Arc thread segment bolts, hexagon head arc thread segment bolts. In addition, the segment connecting bolts can also be classified according to the stress. There are usually 3 grades, namely: 5.8 machine (material is Q235), 6.8 (material is 45#), 8.8 (material is 40Cr) ), in which the surface treatment is galvanized.

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The tunnel segment bolts can assemble several segments together. Some of the segments have a certain arc, and some are straight. The connection and fastening between segments depends on the action of segment connection bolts. The application range of segment connection bolts It is widely used in building segment connection, shallow buried longitudinal segment bolt, Subway Line shield, Subway Line segment connection, tunnel segment connection and other projects.

double end straight stud bolt
Dimension Arc Length mm Tensile Strength Surface Treatment
M25~M39 480~880 4.6、4.8、5.6、5.8、8.8 Dacromet, Hot dip Galvanized
hex head arc segment bolt
Dimension Arc Length mm Tensile Strength Surface Treatment
M25~M48 480~880 4.6、4.8、5.6、5.8、8.8 Dacromet, Hot dip Galvanized

Subway Line Tunnel Shield Bolt Application

Subway Line Tunnel shield bolts are not a special kind of bolts, but a general term for certain types of bolts that are often used in Subway Line construction. Subway Line tunnel shield bolts are characterized by high anti-corrosion standards, good steel performance, and curved and straight shapes. The bolts used to repair Subway Line cement structures are called Subway Line bolts. They are widely used in mines and Subway Line projects. Subway Line bolts include longitudinal and circumferential Subway Line bolts. In some projects, longitudinal and circumferential Subway Line Tunnel bolts are the same specification. In some projects, the longitudinal and circumferential Subway Line bolts are of two different specifications with different strength levels.

Dimension R B Project
M30X610 380 45 Shanghai Subway Line
M30X617 360 42 Suzhou Subway Line
M30X620 360 42 Hangzhou Subway Line
M30X617 360 42 NanJing Subway Line
M30X627 360 42 NanJing Subway Line
M30X617 360 42 Wuxi Subway Line
Dimension R Arc Length B Project
24X531 350 476 55 BeiJing Subway Line 7
24X531 350 476 55 BeiJing Subway Line 6
24X521 350 471 S0 BeiJing Subway Line 10
24X523 350 473 50 NanJing Subway Line 2
24X516 3S0 463 50 Shenyang Subway Line 2
24X505 350 460 45 Shenyang Subway Line 1
27X518 350 473 45 Zhengzhou SubwayLine
27X518 350 473 45 Changsha Subway Line 1
27X518 350 473 45 Wuhan Subway Line 2
27X540 380 497.5 42 Xian Subway Line 2
Dimension R B Mechanical Property Project
M30X606 436 170 8.8 BeiJing South-to-north water diversion Tunnel
M36X667 489 180 8.8 BeiJing South-to-north water diversion Tunnel
M30X606 436 170 8.8 First underground railway tunnel
M36X667 489 180 8.8 First underground railway tunnel

Subway Line tunnel segment bolts are used in many projects and are a common fastener. However, due to the working environment, rust and corrosion are prone to occur during use. Corrosion of Subway Line segment bolts not only affects the appearance of Subway Line segment bolts, but also affects the mechanical property, such as the mechanical properties and tensile strength of Subway Line segment bolts will be reduced, so that the service life of the segments and Subway Line segment bolts will be reduced. This will not only increase the cost of the enterprise, but also increase the difficulty of subsequent maintenance work. Therefore, when using Subway Line tunnel segment bolts, attention must be paid to the anti-corrosion treatment.

tunnel shield segment bolt production

Subway Line tunnel bolts are mainly used in Subway Line construction projects, mainly assembling segments together to form pipes. They work in a humid environment, so in order to prolong its service life, we need to do anti-corrosion treatment. Before the tunnel shield bolts are used, some inspection work should be done to observe whether the shape and size of the Subway Line tunnel bolts are abnormal, the arc of the rod is normally bent, and whether the tensile load is normal.

Mechanical Property of Subway Line Tunnel Segment Bolt

Mechanical and Physical Properties Performance Level
3.6 4.6 4.8 5.6 5.8 6.8 8.8
d≤163) d>163)
Nominal Tensile Strength  N/mm2 300 400 500 600 800 800
Minimum tensile strength N/mm2 330 400 420 500 520 600 800 830
Vickers hardness HV F≥98N min 95 120 130 155 160 190 250 255
max 2206) 250 320 335
Brinell hardness HB F=30 D2 min 90 114 124 147 152 181 238 242
max 2096) 238 304 318
Rockwell hardness HR min HRB 52 67 71 79 82 89 / /
HRC / / / / / / 22 23
max HRB 95.06) 99.5 / /
HRC /   32 34
Surface hardness HV 0.3 max / 7)
Yield point N/mm2 Nominal 180 240 320 300 400 480 / /
min 190 240 340 300 420 180 / /
Specified non-proportional elongation stress N/mm2 Nominal / / 640 640
min / / 640 660
Guaranteed stress N/mm2 0.94 0.94 0.91 0.93 0.9 0.92 0.91 0.91
180 225 310 280 380 440 580 600
Breaking torque MB,N.m min / according to GB/T3098.13 regulations
Elongation after breaking % min 25 22 / 20 / / 12 12
rate of reduction in area % min / 52
Shock absorption work Aku,min   25   30 30
Head firmness No break
Minimum height of undecarburized thread E / 1/2H1
Maximum depth of fully decarburized layer G,mm / 0.015
Hardness after tempering / The difference between the average hardness before and after tempering is not more than 20HV
Surface defects According to GB/T 5779.1 or GB/T 5779.3 regulations

Surface Treatment of Tunnel Segment Bolt

Tunnel Segment Bolt Surface Treatment
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