Shield construction

1. Construction conditions of shield method

【Formula】Homogeneous buried deep groundwater, cross-section affects sharp turns

(1) Applicable stratum range: Relatively homogeneous geological conditions except hard rock, it should be noted that Guangzhou and other regions have had successful experience in using composite shield construction of soft and hard uneven strata.

(2) Tunnel burial depth: The tunnel should have sufficient buried depth, and the covering depth should not be less than 1D (tunnel diameter). When the compressed air construction method and the slurry pressurized shield are adopted, the tunnel covering is too shallow, and there is the possibility of roofing; The maximum overburden also has limitations, depending on the resistance of the shield to groundwater and the waterproofing performance of the lining.

(3) Groundwater prevention and control: When using closed shield, in addition to the needs of the starting and receiving areas and the opening and changing tools, there is generally no need for auxiliary construction methods.

(4) Cross-sectional shape: The standard shape is circular. Profiled cross-sections can also be used.

(5) Cross-sectional size: In addition to the commonly used Φ6~Φ7m diameter of subway shield, there are examples of applying diameter Φ11.58m and Φ10.22m shield in Shanghai Metro and Beijing Metro to build subway up and down lines at the same time. At present, the construction technology of Φ15m super-large diameter slurry balance shield in soft soil has been relatively mature.

(6) Sharp turning construction: there are construction examples with the ratio of curve radius/shield outer diameter of 3~5.

(7) Impact on the environment: When approaching the construction of existing buildings (structures), auxiliary measures are sometimes required; Except for the working well part, it has little impact on road traffic; Vibration and noise are generally limited to the vicinity of the mouth of the working well, and can be protected by soundproof walls.

2. Preparation for shield construction

【Formula】Adjustment of technical well excavation

(1) Preliminary investigation

(2) Technical preparation

(3) Selection of working well location and construction method

(4) The size of the working well section is determined

(5) Preparation before excavation

3. Pre-construction investigation of shield tunneling

【Formula】Electricity in the underground environment

(1) Investigate the geological and hydrogeological conditions of the construction site, and supplement the geological survey if necessary.

(2) On-site survey and investigation should be carried out on the ground buildings (structures) within the scope of the project, and detailed investigations should be carried out on the buildings (structures) that need to be reinforced or underpinned by foundations, and appraisal should be carried out if necessary, and the construction plan should be prepared in advance.

(3) Underground obstacles, underground structures and underground pipelines within the scope of the project should be investigated, and if necessary, they should be explored.

(4) According to the environmental protection requirements of the project location, the project environmental survey shall be carried out.

(5) Investigation of the introduction conditions of electricity consumption of shield equipment.

4. Technical preparation for shield construction

【Formula】Graphic and textual shield survey

(1) Engineering geology and hydrogeological survey report.

(2) Investigation of the environment, buildings (structures), underground pipelines and obstacles along the tunnel.

(3) Design drawings and engineering technical requirements required for construction.

(4) Contract documents related to project construction.

(5) Construction organization design.

(6) Relevant information on the proposed use of shield.

5. Selection of shield working well location and construction method

【Formula】 The vibration and noise alternate end is always, and the safety economy affects the open digging well

When the shield method is adopted, it is generally necessary to set up a working well at the beginning and end of the shield tunneling, which is divided into the shield starting working well and the receiving working well according to the purpose of the working well, and is mostly used as a permanent structure such as subway station, drainage and ventilation after completion. The location selection of the working well should not affect the surface social traffic, have less impact on the noise and vibration of nearby residents, and can meet the needs of the construction and production organization. The working well should be based on geological conditions and environmental conditions, and the construction method that is safe, economical and has little impact on the surrounding area should be selected, and the open-cut method is usually used for construction.

6. The cross-sectional size of the shield working well is determined

【Formula】Flat bottom, full of length and width

The plane size of the starting working shaft should be determined according to the construction requirements of the shield installation.

The wall of the well is provided with the shield starting opening, and the well is provided with the shield base and the reaction frame.

The length of the starting working shaft should be greater than the length of the shield host by 3m, and the width should be greater than the diameter of the shield by more than 3m; The size of the starting working well should meet the requirements of the unearthed hoisting of the battery car and the hoisting of segments and the installation of personnel going down the stairs.

The in-plane net size of the receiving working well should meet the requirements of shield receiving, dismantling and turning;

The bottom plate of the launching and receiving working wells should be lower than the bottom elevation of the starting and arriving doors, and should meet the minimum working space requirements required for the installation and dismantling of related devices.

7. Preparation before shield tunneling

【Formula】Review the storage table

(1) Review the mileage and coordinates of each working well, the accuracy of the steel ring of the hole door and the elevation and coordinates after installation.

(2) Inspection and acceptance of shield base, negative ring segment and reaction frame and other facilities and directional measurement data.

(3) Segment and auxiliary material reserves.

(4) Various reports of shield tunneling construction.

(5) Inspection and acceptance of the soil reinforcement at the entrance and the sealing and water-stopping device of the door.

8. Basic requirements for the layout of the shield construction site

【Formula】According to the internal elimination equipment, the road warehouse yard room line mixing pit

(1) The layout of the construction site shall be based on the requirements of the contract period and the construction schedule, and the spatial relationship between the facilities required during the construction period shall be correctly handled in the specified construction area.

(2) Within the scope of the construction land, make reasonable planning and layout for road traffic, material warehouses, material storage yards, temporary houses, large-scale construction equipment, soil (mud) pits, slurry mixing systems, temporary water and electricity pipelines, fire-fighting equipment, vertical transportation equipment, etc. on the construction site.

9. Layout of the shield construction site

【Formula】Well prevention vertical transport field, three stations and three roads

It mainly includes shield working shafts, rain shelters and floodproof walls of working wells, vertical transportation equipment, segment storage yards, segment waterproof treatment yards, slurry mixing stations, material tool rooms and machine repair rooms, synchronous grouting and soil improvement mud mixing stations, two-circuit transformer and distribution rooms and other facilities, as well as access channels.

10. Shield construction facilities are set up

【Formula】Mud charging pump machine room

(1) When precipitation measures need to be taken for the construction of working wells, a considerable scale of precipitation system (water pump room) should be set up.

(2) When the pneumatic shield construction is adopted, an air compressor room should be set up at the construction site to supply sufficient compressed air.

(3) When the slurry balance shield is used for construction, a mud treatment system (central control room) and a mud pool should be set up at the construction site.

(4) When the EPB shield is used for construction, facilities such as electric locomotive battery charging room should be set up.

11. Assembling and debugging of the shield

【Formula】The plan reorganizes the ground load capacity, and eliminates the special air debugging

(1) The following preparations should be completed before assembly:

1) According to the situation of the shield components and site conditions, formulate the assembly plan.

2) Select lifting equipment according to the size and weight of components, and at the same time select assembly equipment according to site conditions.

3) Verify the bearing capacity of the foundation at the lifting position.

(2) The shield assembly shall be carried out in accordance with the safety operation procedures and assembly plan.

(3) The site should be equipped with fire-fighting equipment, and a special person must be responsible for open flame and electric welding operations.

(4) After assembly, the no-load debugging of each system should be carried out first, and then the no-load debugging of the whole machine should be carried out.

Yesterday 速记口诀5/9

1. The type of shield is classified according to the form of supporting strata

Natural mechanical earthy gas

2. The type of shield is classified according to whether the excavation face is closed

Water and soil hand half machine

3. The type of shield is classified according to the shape of the section

Round horseshoe, multi-class moment

4. The configuration of the cutterhead of the shield machine

Body knife measuring rod tube

5. Cutterhead design matters

The structure uses an open knife

7. The function of the cutterhead

Dig and stir

8. The applicability of the shield to geological conditions

The soil is clay, muddy and watery

9. Selection basis

Survey and set up a broken safety ring, and the field period is auxiliary to the class

10. The basic principles of selection

Fit for the first time

11. Requirements for shield selection and configuration

The shell disc drives the cylinder with snail mud, and changes the human reaming guide

Three days ago, shorthand mantra 5/7

1. Basic provisions for foundation pit (groove) earthwork excavation

The excavation and protection case is prohibited, and the collision and disturbance are stopped

2. Stop the abnormal situation of excavation

Slope branch around the bottom of the curtain pit

3. The excavation sequence of foundation pit blocks

The long original end is in the middle, and the well is first on the diagonal brace

4. Deformation characteristics of foundation pits

Wai Shen Long

5. Causes of soil deformation

Excavation, unloading, and relocation of the perimeter

6. Horizontal deformation of the enclosure structure

The triangular flat rigid abdomen protrudes

7. The reason for the vertical displacement of the enclosure structure

The sediment is worn and sunk

8. Causes and hazards of excessive uplift at the bottom of the foundation pit

The reinsertion of the column supervisor is unstable

9. Characteristics of surface subsidence

Hanging next to the wall, propping up from the wall

10. The main method of controlling the deformation of the foundation pit

Increase or decrease reinforcement tone

11. Stability control at the bottom of the pit

Deep-grained precipitation is used as a baseplate

Seven days ago, shorthand mantra 5/3

1. The role of precipitation

Intercept seepage and stabilize the slope to prevent flow, and lift the shear pit to stabilize and reduce water power

2. Basis for the selection of engineering precipitation methods

Soil and water infiltration depth

3. Engineering precipitation method

Trap jet pipe latent infiltration

4. Collect water and drain it

Ditch well slope seepage pumping subsidence

5. Vacuum well point layout

The construction site is a deep water pit, and the main pump is far from the deep pipe into the soil

6. Vacuum well point and jet well point well formation method

Drilling and punching deep dilute filter seal

7. a tube well

The bottom of the pipe diameter slurry is made into a hole

8. Irrigation

The water drop needs to be protected, and the depth of the well is pressed at the top

9. Factors influencing the characteristics of groundwater seepage

Destination depth aquifer

10. The water separation (interception) curtain of the foundation pit and the precipitation inside and outside the pit are arranged

The inside and outside of the bottom pit, and the pressure in the pit in the layer is reduced

Two weeks agoShorthand formula4/26

The bridge is waterproof and protected, and the mold sliding group is set up.

The bowl plate buckle mast is pre-pressed, and the machine is connected with cold ribs and hot residual coating.

Pre-anchor clamping for Paipu, strong welding of wire pipes

五周前速记口诀4/6

1. Micro-surface processing process

Milk Modification Loading / Feeding

2. Applicable conditions for micro-surface treatment process

The strength of the structure is fully undamaged

3. Micro-table processing technology function

Water sealing, anti-slip and wear-resistant

4. Basic requirements for the construction of micro-meter processing projects

Digging and irrigation

5. Construction process and requirements of micro-meter processing project

Try to remove the moisturizing spray and flatten the culture

6. The treatment of the old asphalt pavement by the asphalt mixture surface layer

Strong damage is compensated at the same level

7. The treatment of the old cement concrete pavement by the asphalt mixture surface layer

Investigate fill-in-the-blank ticks

8. Preventive measures for horizontal deformation and reflection cracks of the old cement surface layer

Stress Reduction Layer

9. Preventive measures for vertical deformation and damage of the old cement surface layer

The bureau is broken and repaired, and the seam paste is filled

10. Treatment of the base of the old cement surface layer

Local crack replacement fill-in grouting

11. Treatment of cement concrete pavement disease

Broken and misaligned

12. The cement concrete pavement is paved with asphalt concrete surface layer

The elevation of the tube well position, the junction of the interring energy, and the soft place of the oil sprinkler

Shorthand mantras

1. Construction conditions of shield method

Homogeneous buried deep groundwater, cross-section affects sharp turns

2. Preparation for shield construction

Adjustment well excavation

3. Pre-construction investigation of shield tunneling

Electricity consumption in the underground environment