This regulation is formulated to unify the technical requirements for the jacking construction of urban tunnel bridges across the country, to achieve advanced technology, economic rationality, safety and reliability, to ensure construction quality, and to standardize engineering construction. This regulation is applicable to tunnel bridge projects built under railway operating conditions where roads cross railways. CJJ 74-1999 Regulations for the jacking construction and acceptance of urban tunnel bridges CJJ74-1999 Standard download decompression password: www.bzxz.net

Engineering Construction Standard Full-text Information System
Industry Standard of the People's Republic of China
Specification for construction and acceptance of underpass bridges in town
by jacking method
CJJ74—99
1999·Beijing
Engineering Construction Standard Full-text Information System
Engineering Construction Standard Full-text Information System
Industry Standard of the People's Republic of China
Specification for construction and acceptance of underpass bridges in town by jacking method
CJJ74—99
Editing Unit: Shijiazhuang Municipal Construction Corporation of Hebei Province Approving Department: Ministry of Construction of the People's Republic of China Effective Date: July 1, 1999
1999·Beijing
Engineering Construction Standard Full-text Information System
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Notice on the Release of Industry Standard "Regulations for Construction and Acceptance of Urban Underground Bridges"
Construction Standard [[1999]] No. 19
According to the requirements of the Ministry of Construction's "Notice on Issuing the 1993 Engineering Construction Industry Standard Formulation and Revision Project Plan (Part of the Second Batch of the Ministry of Construction)" (Construction Standard [1993] No. 699), the "Regulations for Construction and Acceptance of Urban Underground Bridges" edited by Shijiazhuang Municipal Construction Corporation has been reviewed and approved as a mandatory industry standard, numbered CJJ74-99, and will be implemented from July 1, 1999. This standard is managed by the Beijing Municipal Engineering Design and Research Institute, the Ministry of Construction's urban road and bridge standard technology management unit, and Shijiazhuang Municipal Construction Corporation is responsible for the specific interpretation. bZxz.net
This standard is published by the China Building Industry Press organized by the Standard and Quota Research Institute of the Ministry of Construction.
Ministry of Construction of the People's Republic of China
January 25, 1999
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General Provisions…
Jacking Construction Methods
One-time Jacking Method
4.2 Intermediate Room Method
Jacking Method and Half-Jacking Method
Multiple Single Bridge Jacking Method
Jacking Process Design
Site Investigation
Working Pit
Moisture Slippery isolation layer
Jack force calculation
Steel blade foot and middle platform
Jacking equipment
Jacking construction
Construction layout
Construction drainage and precipitation
Working pit excavation
Skateboard construction
Lubricating isolation layer construction
Back construction
Bridge prefabrication
Jacking equipment installation
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6.9 Jacking Operation
6.10 Measurement and Monitoring
6.11 Restoration of Line
Railway Line Reinforcement
Engineering Quality Inspection and Acceptance
Working Pit
Appendix A
Appendix B
Appendix C
Appendix D
Appendix E
Skateboard and Lubricating Isolation Layer·
Bridge Prefabrication
Bridge Waterproofing
Bridge Jacking
Construction Measurement
Working Pit Seepage Calculation
Skateboard Anti- Sliding stability verification
Stability verification of back wall
Underground bridge jacking construction record sheet
Terms used in this regulation
Additional explanation
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Engineering Construction Standard Full Text Information System
1 In order to unify the technical requirements for the jacking construction of urban underground bridges across the country, to achieve advanced technology, economic rationality, safety and reliability, to ensure construction quality, and to standardize engineering construction, this regulation is formulated.
2 This regulation is applicable to underground bridge projects built under railway operating conditions where roads cross railways.
1.0.3 During the jacking construction of underground bridges, process design and construction organization design should be carried out. 1.0.4
In addition to complying with this code, the construction and acceptance of urban underpass bridges shall also comply with the provisions of the relevant national mandatory standards in force. Engineering Construction Standard Full-text Information System
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2.0.1 Underpass Bridge
Gradually intersecting road under the railway. 2 Jacking Method
A construction method that uses jacking equipment to gradually push prefabricated box-shaped structures into the roadbed to form a three-dimensional intersection passage.
2.0.3 Box-bridge
The underpass bridge constructed by jacking has a frame structure to become a box-shaped bridge.
Working Pit
The working area for prefabrication and jacking of the bridge body.
5 Bed-way
The bottom plate of the working pit, which is also the slideway during jacking. 2.0.6 Reaction pedestal
A temporary structure that bears the jacking reaction force of the bridge structure. 2.0.7 Hanging bridge of track Within the scope of railway line reinforcement, the two sides of the running rails are bundled with 3 or 5 rails, which are fastened to the sleepers by U-shaped clips and buckles to form a suspended rail beam, so that the reinforced line has a certain overall rigidity. 2.0.8 Jack blick
Force transmission equipment made of steel.
2.0.9 Jacking force
The force applied to overcome the soil resistance, frictional resistance between the bridge and the soil, and the frictional resistance of the railway line and reinforcement materials during the jacking of the bridge. 2.0.10 Jacking force factor The ratio of the jacking force of the bridge body to the deadweight of the bridge body.
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2.0.11 Intermediate jack station A workroom set up between the sections of a multi-section bridge body for arranging jacking equipment. (See Figure 4.2.1)
2.0.12 Pull and push method A construction method in which three or more sections of a bridge body are jacked, and the rear section is connected to the front section with a steel tie rod, so that the front and rear sections of the bridge body are backed to each other and jacked alternately. (See Figure 4.3.1) 2.0.13 Semi-pull and push method Semi-pull and push method When the jacking method is constructed, due to the lack of static friction resistance of the front and rear sections, the backing still needs to be set for jacking, which is called semi-pull method.
2.0.14 Downward heading
When the center of gravity of the bridge body moves to the front edge of the slide during jacking, the front part of the bridge body enters the uncompacted soil foundation and deforms and sinks under the action of the railway live load. Engineering Construction Standard Full Text Information System
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3 General Provisions
3.0.1 The number of holes, span and clear height of urban tunnel bridges shall comply with the provisions of relevant specifications such as urban planning and the current national "Urban Road Design Code" (CJJ37) and "Railway Bridge and Culvert Design Code" (TBJ2).
3.0.2 The construction organization design or targeted construction technical plan shall be organized according to the soil conditions. When there is groundwater, the groundwater level shall drop to 0.5-1.0m below the base before construction can be carried out. Tunnel bridges shall not be jacked in the rainy season. 3.0.3 A construction cooperation agreement shall be signed with relevant railway departments. Before the jacking operation, the railway department shall reinforce the railway line within the construction scope according to the design drawings and construction organization design.
3.0.4 When the tunnel bridge is jacked as a whole, its length should not be greater than or equal to 30m. If it is greater than 30m, it should be divided into sections in the longitudinal direction. The length of the first section should be 1.5 to 2.5 times the height of the bridge.0 times. The joints of the longitudinal sections should be set between the railway lines. 3.0.5 When the width of the multi-hole tunnel bridge exceeds 45m, it is advisable to decompose it into multiple single bridges horizontally, and adopt separate jacking or synchronous jacking according to the construction period and the conditions of the jacking equipment. 3.0.6 The jacking surface of the bridge body should be perpendicular to the center line of the road, and a steel pad should be set. When the inclined bridge is jacked, the bridge body bottom plate jacking triangle block should be set at the force-bearing part (see Figure 5.6.3), and technical measures for correcting deviation should be taken. 3.0.7 The length of the bridge body tail wall should not be less than 0.4 times the height of the bridge. 3.0.8 During the jacking process of the tunnel bridge, the line reinforcement system, various parts of the bridge body, the jacking system and the back should be measured and monitored. The measurement and monitoring plan should be included in the construction organization design or construction technical plan.
3.0.9 The tunnel bridge structure can adopt a box frame structure, an arch structure or a decomposed structure.
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Jacking Construction Method
4.1 One-time Jacking Method
1 The one-time jacking method (Figure 4.1.1) is used for construction. The bridge body should be prefabricated as a whole. A jack is set at the end of the bridge. With the help of the back reaction force, the single-hole or multi-hole bridge body is pushed into the railway roadbed at one time.
Figure 4.1.1 One-time Jacking Method
1-bridge body; 2-slide plate; 3-jack; 4-crossbeam; 5-jacking column, 6-back 4.25
Relay Room Method
4.2.1 When the multi-section bridge body is jacked using the relay room method (Figure 4.2.1), jacks should be set in the relay room at the multi-section bridge body section and at the end of the bridge body, and each section should be jacked in sequence. The jacking force of the front section should be provided by the static friction resistance and back reaction force of the subsequent sections. When the conditions of the back comprehensive resistance allow, combined jacking can be used. 4.2.2 The position and size of the relay room should be determined according to the shape and number of the jacks used.
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Figure 4.2.1 Relay Room Method
1, 2, 3-bridge body, 4-jack; 5-top column, 6-back; 7-steel beam; 8-scissor hinge; 9-relay room4.2.3
In the prefabricated bridge body on site, each section of the bridge body can be prefabricated in series or in parallel4.3 Top-pull method and semi-top-pull method
4.3.1 When the top-pull method (Figure 4.3.1) is used for construction, the bridge body should not be less than three sections. Among the commonly used lubricating isolation layers, materials with relatively large friction coefficients should be selected. Force transmission piers, tie rods, tie beams, etc. should be installed between the sections as force transmission equipment. Jacks should be installed in the relay room, the tail of the bridge body and the force transmission piers.
4.3.2 The design jacking force should be calculated according to the most unfavorable situation based on the sections of the bridge body, the length of each section and the static friction resistance of each section.
4.3.3 When the semi-top pulling method is used for construction, the bridge body should not be less than two sections. Several commonly used lubricating isolation layers should be selected from low friction materials, and the static friction resistance of each section should be fully utilized. It should be converted into the reaction force required for the jacking section through force transmission piers and tie rods, and the insufficient part should be provided by the back.
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Figure 4.3.1 Jacking and pulling method
1-front section of the bridge, 2-middle section of the bridge, 3-rear section of the bridge, 4-jack, 5-pull rod, 6-steel tension beam, 7-footage
4.4 Jacking method for multiple single-unit bridges
4.4.1 When multiple single units are jacked in stages, the net distance between the bridge bodies should not be less than 0.2m. The influence of the soil pressure on one side on the displacement force of the bridge body should be taken into account during jacking. 4.4.2 The synchronous jacking of multiple single-unit bridges should be regarded as the overall jacking of multi-hole bridges, and the relevant positions during jacking should be adjusted at any time.
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