1. Project Overview
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2. Construction Principles
Before construction, the weak surrounding rock should be carried out on site Carefully investigate and deeply understand the design intention, and prepare practical construction plans based on different geological conditions. During construction, we strictly adhere to the principles of "pay attention to geology, advance pipes, strict grouting, short footage, strong support, diligent measurement, and early closure". , Strictly implement relevant regulations on tunnel construction.
3. Construction technology and construction plan
The tunnel's level III surrounding rock section will be constructed using the full-section method, while the level IV and V level surrounding rock section will be excavated using the step method. Initial support with anchors, nets and spraying is adopted, inverted arches are advanced, and the arch walls are once lined. The seismic fortification lining section of the active fault zone adopts the full ring grid steel frame of the arch wall and double-layer φ42 small conduit at the arch for advanced support, and the cave is lined. Use lining trolley.
During construction, advance geological prediction of the tunnel was carried out, and blast hole detection was deepened. Infrared detection method was used to conduct advance geological confirmation to determine whether there were design differences. Advanced horizontal drilling was used for key geologically dangerous sections mentioned in the drawings, measurements were done carefully, and settlement observations were analyzed.
4. Excavation and support of the cave body
The excavation of the cave body adopts the New Austrian method.
The V-level surrounding rock section is excavated using a three-step and seven-step method. The shallow buried section of Class V surrounding rock is located at the entrance of the tunnel. Advanced geological forecast, short footage, weak blasting, early closure, and frequent measurement ensure construction safety.
Construction operation process: advanced duct support → excavation on the steps → initial spraying → installation of grating or steel frame → combined hollow anchors at the arch → hanging net → re-spraying → excavation of the middle steps → Initial spraying → Vertical side wall grille steel frame → Hanging netting → Side wall radial anchors → Repeated spraying → Excavation down the steps → Initial spraying → Vertical side wall grille steel frame → Hanging netting → Side wall radial anchors →Re-spray.
The level IV surrounding rock section is excavated using the arc-shaped guide pit step method.
Advanced duct support → Excavation up the steps → Initial spraying → Installation of grilles or shaped steel frames → Arch combination hollow anchors → Hanging nets → Repeated spraying → Excavation down the steps → Initial spraying → Vertical side wall grille steel frame → side wall radial anchor → re-spraying.
Excavation using the step method in the III-level surrounding rock section.
Construction operation process: excavation on the steps → initial spraying → hollow anchors in the arch → hanging net → re-spraying → excavation down the steps → initial spraying → side wall radial anchors → re-spraying.
Construction of step method for level 5, Ⅳ, and Ⅴ surrounding rock
Level Ⅳ and Ⅴ surrounding rock shall be excavated using the step method, and the distance between the upper and lower steps shall not exceed 1.5 times during excavation. Width, allow 5 to 10cm of settlement at the arch (make appropriate adjustments based on measurement). The upper and lower steps are drilled using rock drilling rigs and manual hand-held YT-28 rock drills, smooth blasting, and non-electric millisecond detonator network detonation. Areas with soft surrounding rock will be excavated using excavators and manpower. An excavator and a loader are used to excavate and install ballast on the lower steps. During construction, the left and right steps were staggered by three meters.
Before drilling, measure the top line and center line of the inner rail, draw the excavation outline, and mark the blasthole position according to the design (when geological conditions change, adjust the drilling position appropriately). The diameter of the drill hole is φ42mm, the depth of the upper step cut hole and bottom hole is 1.4-1.6m, the depth of other blastholes is 1.3m; the depth of the lower step blasthole is 3.1m.
After drilling is completed, check and record according to the blasthole layout plan. Any blastholes that do not meet the requirements will be re-drilled. Before charging, blow out the mud and stone powder in the blastholes with high-pressure air, check the blastholes, and charge after confirming that they meet the design requirements. When loading, strictly follow the designed dosage. After charging, all blastholes are clogged with clay. The peripheral eyes use interval charging and are connected with detonating cords. The cutout eyes use concentrated charging. The bottom 30% of the length is reinforced with charging. The other eyes use concentrated charging.
The blasting network uses micro-difference, non-electrical millisecond detonators to detonate. The non-electrical millisecond detonator is inserted into the cartridge and loaded into the eyelet in reverse. The detonating tube fuse connection adopts a "grab" type.
6. Construction of mortar anchors
The anchors use Ф22mm threaded steel bars. Before construction, check whether the anchor type, specification, quality and performance are consistent with the design. Prepare drilling equipment according to the type and specification of the anchor rod and the surrounding rock conditions.
Pneumatic drills are used for drilling. The hole spacing, depth and arrangement meet the requirements of the design parameters, and the direction is perpendicular to the rock layer. Use a pneumatic mixer to drive the anchor rod to rotate quickly and slowly advance while rotating.
In order to check the installation quality of the anchor rod, the pullout resistance test of the anchor rod is carried out as required, and a tension meter is installed. Its line of action is concentric with the anchor rod and fixed firmly.
The loading is uniform and slow, and the drawing stops when the designed tonnage is reached. No destructive testing is performed.
7. Advance construction of small conduits
Small conduits are made of steel pipes, with the front end closed and made into a pointed shape so that they can be inserted smoothly into the drilled hole. Arrange grouting holes in a plum blossom pattern on the pipe wall. The length of the grout-stopping section at the tail should be no less than 30 cm, and the external insertion angle should be 10°-15°.
First use a pneumatic drill to open the hole. The diameter of the opening is 50mm, and the sand and gravel are blown out with a blowpipe. Then use a pneumatic drill with an impact to push the small conduit into the hole, or directly hammer into the steel pipe. Finally, use plastic putty to seal the area around the pipe and the opening, and seal the cracks on the working surface. The grouting pressure is controlled at 0.5-1.0Mpa.
8. Steel frame fabrication, installation and construction
Steel frame processing is carried out in the steel processing field according to the reserved amounts of different surrounding rocks.
After the steel frames of each unit of the steel frame are processed according to the design, a trial assembly is organized to check whether the size and outline of the steel frame are qualified, and a structural test is conducted on it.
The specific detection method is: assemble the steel frame into a ring on the workbench, use oil caps and instruments on the outside to pressurize according to the design load, and use steel stress gauges and convergence instruments to detect the internal force of the steel frame. and deformation. Strictly control the drilling size of the gusset plate.
The steel frame is installed after initial spraying of concrete according to the design requirements. The thickness of the steel frame covered by sprayed concrete shall not be less than 4cm.
9. Spray concrete construction
After the tunnel section is formed, spray concrete protection work should be carried out in a timely manner. The spraying sequence is symmetrical from bottom to top, first spraying the gap between the steel frame and the surrounding rock, then spraying around the steel frame, and then spraying between the steel frames. Spray concrete covers the entire grid steel frame, and the protective layer thickness is ≥2cm. Wet spraying of spray concrete is carried out using a wet spraying machine. The initial spraying thickness is 3cm, and the spraying is repeated to the designed thickness. Concrete spraying uses two wet spraying machines to spray simultaneously from both sides of the side walls to speed up the construction progress, so that the grid steel frame and the sprayed concrete can be connected as a whole in time to play a supporting role.
Check the dimensions of the excavation section before spraying. Remove pumice on the excavation surface and rock ballast and accumulations in the corners. Treat the rock surface, remove obstacles, repair the under-excavated parts, and install a working platform if necessary. Wash the sprayed surface with high-pressure air. Conduits should be buried in the dripping parts of the sprayed surface for drainage. Blind ditches can be set up for drainage in aquifers with poor water conductivity, and interceptor circles can be set up for drainage at dripping locations. Embed signs to control concrete thickness. Have good ventilation and adequate lighting. Before spraying operations, conduct a comprehensive inspection and trial operation of mechanical equipment, air and water pipelines, and electrical lines.
According to the wet spray concrete mix ratio provided by the central laboratory, the mixing is completed at the mixing station, and the slump is checked to keep it at 5 to 8 cm. The mixture is transported to the wet spraying machine in a concrete transport tanker, and the liquid quick-setting agent is added from the nozzle through the wet spraying machine and sprayed onto the sprayed surface.
The spraying operation is carried out in sections, and the spraying sequence is from bottom to top; re-spraying is carried out after the previous layer of concrete has finally set. When the spraying operation starts, the air is supplied first, then the machine is turned on, and then the material is fed. At the end, the material is first stopped, and then the air is stopped. The jet machine supplies materials continuously and evenly. When the machine is operating normally, sufficient material is maintained in the hopper, and the working air pressure of the jet machine is controlled at 0.45~0.7Mpa. When the spraying operation is completed or the spraying is interrupted for any reason, clear the accumulated material in the sprayer and the feeding pipe.
The sprayer always keeps the nozzle perpendicular to the sprayed surface at a distance of 0.6 to 1.0m, and at the same time controls the flatness of the concrete surface. Two hours after the final setting of the spray concrete, sprinkle water for curing. The curing time shall not be less than 7 days.
10. Invert and filling construction
During construction, the invert should go first and be closed as early as possible to facilitate the overall stress bearing of the lining structure.
The inverts are poured in sections. Each section of the invert excavation is controlled to be 3 meters long and each section is 5~10m long. Before concrete pouring, the empty ballast and water accumulation at the bottom of the inverts should be cleaned up and passed the inspection by the supervision engineer. Concrete is poured after tying the steel bars. When pouring the invert concrete, proceed symmetrically from the center of the invert to both sides. Concrete pouring is transported by tanker truck, the invert arc is strictly controlled, and the invert and invert filling are poured separately.
After the inverted arch concrete reaches the design strength, pouring and filling of concrete will be arranged. Before filling concrete construction, remove debris, dust and water on the inverted arch surface.
In order to achieve parallel operations with excavation and lining, invert arch construction requires a trestle to be set up on the invert arch working surface to ensure the normal movement of various operating vehicles without damaging the newly poured invert arch concrete.
11. Structural waterproofing and drainage construction
A composite waterproof board is installed on the arch wall between the tunnel lining shotcrete and the molded lining concrete, and a circumferential φ50mm soft permeable pipe blind is installed every 8m. Along the trench, the setting of the circumferential blind pipe can be adjusted accordingly according to the water outlet conditions of the tunnel during construction. A centralized water outlet point should be set up, and a φ100 longitudinal permeable blind pipe should be set at the bottom of the side walls on both sides. Drainage pipes should be drilled. The corrugated pipe is wrapped with geotextile.
Before the waterproofing board is installed, the tunnel clearance must be measured and checked. The clearance requirements must meet the tunnel design excavation outline. The base surface must be flat, with no obvious undulations, and no sharp protrusions such as steel bars and protruding pipe fittings. Otherwise, it must be cut off, and the cut-off area must be smoothed with mortar to round the curved surface to prevent the waterproof layer from being punctured.
When laying the waterproof board, first correctly mark the longitudinal centerline of the tunnel on the top of the sprayed concrete tunnel, and then make the centerline of the cut non-woven fabric coincide with the centerline mark on the sprayed concrete. Start laying down on both sides.
The waterproof board is laid using a nail-free laying process. First, correctly mark the longitudinal centerline of the tunnel on the non-woven fabric at the top of the tunnel arch, and then make the center of the waterproof board coincide with this mark and with the non-woven fabric. The cloth is laid down from the top of the vault to both sides, and the edges are hot melt welded with the gaskets while laying.
The waterproof board connection is welded with a heat sealing machine. The overlap length is 15cm. The joint is a double weld, leaving a cavity in the middle for inspection.
After the waterproof layer is completed, pour concrete in time for protection.
12. Tunnel lining construction
The tunnel lining is constructed using lining benches and combined steel formwork. The platform is made of I-beam steel, and the counterpart supports are made of steel pipes. The formwork adopts special combined steel formwork.
After the excavation and support of the cave body is completed, the displacement rate shown by the construction monitoring test items has slowed down significantly and has become basically stable; the various displacements that have occurred have reached 80% to 90% of the expected displacement. %; carry out side wall and arch lining construction after the horizontal convergence rate (near the arch foot) is less than 0.2mm/d or the vault sinking rate is less than 0.15mm/d. When the support deformation is large, the support capacity is difficult to strengthen, and the deformation has no obvious convergence trend, secondary lining should be implemented in advance after approval by the supervision engineer.
Concrete pouring is carried out symmetrically on both sides at the same time. Pay attention to control the uniformity of pumped concrete on both sides. The height difference of pouring concrete on both sides shall not exceed 50 cm.
Before each lining cycle, the concrete at the joints of the previous set of linings should be chiseled, cleaned, and brushed with a layer of cement slurry to ensure a good connection between the old and new concrete.
Concrete pouring is completed in one continuous pouring. If a power outage or other accident occurs and work must be stopped, the pouring surface should be leveled and vibrated. If the work is stopped for more than 2 hours, the irrigation can be connected after 24 hours.
When the arch is capped, it must be filled and compacted without any gaps.
According to the humidity in the cave, watering or natural health maintenance is used. The formwork should be removed after the concrete in the arch reaches the design strength. When removing the formwork, pay attention to the protection of the corners and surface of the concrete formwork.
13. Construction Surveying, Monitoring Surveying and Geological Advance Forecast
Tunnel surveying work is subject to hierarchical management, and a precision surveying group and a construction surveying group headed by a full-time surveying engineer are established. , are respectively responsible for the work within their respective powers. Strictly abide by the railway engineering measurement specifications to ensure measurement accuracy. The construction measurement level and accuracy standards of this bid section shall be implemented in accordance with the specified requirements.
Before the start of construction, the ground control piles delivered by the design unit are first re-tested and handed over; joint tests are conducted between adjacent bid sections; joint tests are conducted at the entrance and exit of the tunnel, and a wire control network is laid out to monitor the tunnel center line and Elevation is controlled.
Control measurement outside the tunnel: Control measurement outside the tunnel adopts total station measurement. When conducting testing, strengthen contact and coordination with the line to ensure that the penetration measurement is accurate.
In-cave control measurement: The center line measurement in the tunnel uses a total station for precise control measurement, and the control network adjustment and center line adjustment in the tunnel are carried out in a timely manner.
The precision measurement team of the project management department is responsible for the control measurement, phased control measurement and review inspection of the tunnel. It is responsible for reviewing and guiding the construction measurement team of the tunnel construction team to complete the construction measurement tasks, and is responsible for reporting to the construction measurement team On-site intersection points, piles, measurement data and results. Responsible for controlling the measurement of guard piles and protecting all triangular points, level points and control points within the scope of the project.
The construction survey team of the tunnel team is responsible for the daily construction survey, construction stakeout and control pile point burial and protection at the project site.
During the construction of the project, the center line and elevation shall be measured according to the design drawings to ensure that the center line and level are accurate. After the completion of the project, the entire section of the line will be measured and overlapped in a timely manner, and the measurement data will be submitted to the supervision engineer. The original measurement records, data, calculations, and charts must be true and complete, and be properly kept by dedicated personnel.
Conscientiously implement the measurement review system. Field measurement data must be reviewed by a second person. In-house measurement results must be calculated independently by two people and verified by each other before they can be delivered for use. Without the calculation and review by the second person, the results will not be submitted for use. The use of confirmed information is strictly prohibited.
14. Monitoring and measurement
On-site monitoring and measurement is one of the core technologies in the design and construction of new Austrian composite lining. Develop a detailed monitoring and measurement plan during construction, and set up a full-time measurement team to be responsible for daily measurement point burial, monitoring and measurement, data processing and analysis, and instrument maintenance to ensure the reliability of measurement data and provide accurate information for construction and design. basis to ensure the safety, quality and investment of construction.
a. Purpose of measurement
a.1 To grasp the dynamics of surrounding rock during construction and control the deformation of surrounding rock.
a.2 Understand the effect of the supporting structure, take timely measures, and construct safely.
a.3 Provides a basis for optimized design to ensure that the tunnel is both stable and economical.
b. Monitoring and measurement items
Tunnel surrounding rock deformation measurement, stress-strain measurement, surrounding rock stability and support effect analysis.
c. Observation of engineering geology and support conditions
c.1 Observation content: After tunnel excavation, the self-stability, geology and rock quality of the excavation surface and nearby surroundings , check the classification of surrounding rock, and draw a geological sketch map to see whether the structural condition of the initial support (anchor rod, shotcrete, steel support) is damaged.
Observation of the excavation working surface must be carried out after each blasting, especially under weak surrounding rock conditions. Geological surveys should be carried out immediately after excavation. In case of special unstable conditions, special personnel should be sent to conduct it. Observe continuously. Make records after observation and organize and save them.
d. Tunnel clearance convergence measurement
The clearance change measurement and the vault subsidence measurement are in principle carried out on the same section. The spacing between measurement sections is related to many factors such as tunnel length, surrounding rock conditions, and excavation methods.
The clearance change measurement baseline is generally set with two horizontal baselines in the section, and four baselines are set in the section with a burial depth less than 2 times the excavation width and in the expansion or bias section.
Measurement points: fix the short rod of the headroom displacement meter in the rock body of the two measuring points; determine the measurement spacing according to the surrounding rock conditions; measurement accuracy: when the change is relatively small In the case of large changes, it is generally 0.1mm, and in the case of relatively large changes, it is 1mm.
e. Vault subsidence measurement
Vault subsidence measurement points are generally arranged in the middle of the arch and on both sides of the arch. Three points are arranged on each section. When the When there are ventilation ducts or other obstacles, the position can be appropriately moved.
f. Measurement of surrounding rock displacement and anchor axial force
According to the surrounding rock conditions and the importance of the project, 2 to 5 measuring points are set up on each section.
g. Stress and strain measurement of tunnel steel arch frame Underneath the base plate supported by the arch. In strata with compression or expansion forces, when using inverted arch cross braces, the stress box is placed on a special arch frame.
Measure the stress in the lining concrete, arrange several pairs of stress boxes (one radial, one tangential) on the measurement section, and then concentrate the readings on the measurement pipeline.
To measure the stress and strain on the anchor rod, install the pressure box on the anchor rod to form an enlarged washer, which can directly measure the stress value added to the rock mass.
h. The measurement frequency is mainly determined by the displacement rate and the distance between the measuring point and the excavation surface. It is generally selected according to the following table, that is, the testing frequency in the initial stage of burying the original parts should be 1 to 3 times a day. As the rock becomes more stable, the number of measurements can be reduced. When signs of instability appear, the number of measurements should be increased.
Time to end the measurement: When the surrounding rock reaches basic stability, measure for 2 weeks at a frequency of once every three days. If there is no obvious deformation, the measurement can be ended.
14. Geological advance forecast
Geological advance forecast is one of the important means to determine the changes of surrounding rock. It is particularly important in tunnel construction, especially in unfavorable geological sections.
During the construction, a comprehensive advanced geological forecasting system for advanced geological forecasting and advanced exploration drilling was established, using instruments and equipment such as TSP203 advanced geological forecaster, HY303 infrared water detector, horizontal geological drilling rig, etc. to accurately predict the geological conditions ahead and provide reliable information for construction. Technical parameters.
Regularly carry out accurate advance forecasting of the engineering geology, hydrogeology and surrounding rock types in front of the tunnel excavation face, and formulate practical construction methods and construction precautions based on the forecast results. Analyze and compare the prediction effects after excavation, and continuously summarize to gradually improve the accuracy of the geological forecast ahead.
15. Quality assurance measures
Strictly design eyelets and charges for smooth blasting, measure the excavation section, check blasting effects, revise blasting designs, and strive to improve the quality of smooth blasting , effectively control the excavation section.
Establish a monitoring and measurement team, equipped with special measuring instruments, measure according to specified cycles, accurately and completely collect data, analyze and grasp the convergence of surrounding rock, and provide timely feedback information to provide scientific basis for design and construction.
Efforts should be made to improve the quality of anchor and shotcrete support, and the pull-out resistance of the anchor rod and the thickness of the shotcrete layer should be checked according to regulations to ensure that the cross-sectional dimensions comply with the design and the support structure is stable and reliable.
The tunnel is equipped with soft water-permeable blind ditches in the circumferential and longitudinal directions according to the design requirements. During construction, the performance of the waterproof material must be ensured and meet the design standards. When laid, it must be closely adhered to the surface of the shotcrete to ensure the overlap length. The tunnel lining is assembled using shaped steel formwork. The design is carried out first, and trial assembly is carried out before lining. Accurate measurements are taken during the construction process to ensure that the formwork joints are one line in the longitudinal direction and a neat appearance on the circumferential surface.
For the over-excavated parts of the tunnel, the same grade of concrete shall be used for backfilling and density in strict accordance with the specification requirements.
Quality assurance measures for rainy season construction:
Before construction in the rainy season, take protective measures during the rainy season, establish a flood prevention organization, prepare sufficient flood prevention materials, and make all preparations for flood fighting and rescue operations.
During rainy season construction, a dedicated person is responsible for weather forecasting, delivering rain conditions in a timely manner, reasonably arranging processes according to weather trend forecasts, and doing protective work in advance.
Technical measures to ensure that the tunnel does not seep, leak, or crack:
Do a good job of waterproofing and drainage of the tunnel. Ensure smooth drainage behind the tunnel lining, and the waterproof isolation layer can prevent water seepage and leakage, improve the stress conditions of the secondary lining, and reduce the occurrence of cracks in the secondary lining. The amount and flow direction of groundwater may change during tunnel construction and operation. Areas with no or little water during construction do not guarantee no or little water during operation. The waterproof board itself has good waterproof performance, but in During the construction process, the secondary lining is often damaged due to pouring, thus affecting the waterproofing effect. Therefore, we must not underestimate the construction of the waterproof layer or neglect the construction quality just because there is no water temporarily.
The backfill behind the initial support and secondary lining must be dense. Foreign objects or holes must not be backfilled behind the initial support. If necessary, grouting must be backfilled multiple times until it is dense. In order to prevent the secondary lining from being overstressed, monitoring and measurement should be strengthened. According to the measurement results, the construction support parameters should be adjusted to determine the construction time of the secondary lining.
Expansion joints must be made according to the design requirements. The expansion joints must be vertical and straight without any misalignment or bite. The waterstop strips at the expansion joints must be set as required. In order to reduce the construction joints of the secondary lining, continuous pouring must be carried out during the secondary lining. When intermission is necessary, waterstops must be set according to design requirements. For areas with poor geological conditions, such as when the tunnel passes through faults, fracture zones, etc., the tunnel lining structure shall be strengthened according to the design.
In order to avoid cracking of the secondary lining due to subsidence of the base, the side wall foundation must be cleaned before the secondary lining is constructed, and only then can the formwork be erected and poured. Admixtures and admixtures are used, concrete with a low water-cement ratio is configured, and fly ash is used in large amounts to prevent lining cracking. Choosing the type of cement, concrete aggregates and construction water during concrete construction are also the main technical measures to prevent the tunnel from cracking. Do a good job in maintaining the secondary lining concrete to ensure the quality of the concrete.
The cement is stacked in the rainproof shed, and the bottom is paved with wooden sleepers or square logs and waterproof tarpaulin to prevent moisture. All materials and machinery should be placed at a higher place. If necessary, tarpaulins should be supported to prevent rain, and water-blocking and drainage facilities should be provided on the ground.
Standards for construction access roads should be improved to prevent blockage of access roads from impeding the access of materials and construction machinery during the rainy season.
16. Safety measures
Workers participating in tunnel construction must receive safety technical education, be familiar with and abide by tunnel construction technical safety regulations, and undergo safety examinations. Only those who pass the test are allowed to work. , and wear safety protective equipment as required. Operators of various machinery must hold certificates to work, and various machinery and tools should be inspected and tested regularly to ensure that they are in good condition. Full-time safety inspectors often supervise and inspect construction safety. For serious violations of construction safety regulations, they have the right to order a shutdown for rectification until the re-inspection is passed before work can be resumed. Once an accident occurs, it shall be dealt with strictly in accordance with the "three no-passes" approach.
a. Construction safety measures
a.1 Adhere to the principle of taking geology as the guide and always grasp the geological conditions of the section ahead. Special advanced support and initial support should be used for abnormal geology. protective measures.
a.2 Adhere to the principle of roof protection first and then excavation to organize construction: adopt advanced small duct pre-grouting reinforcement measures. Determine the grouting pressure and consolidation range through experiments to ensure that the grouting can be bonded to each other and improve the self-stabilizing ability of the surrounding rock.
a.3 Strictly control the footage per cycle, carry out initial support in time after the excavation is completed, ensure the connection of the processes, and construct inverted arches to form a ring as soon as possible to improve the stress conditions and reduce the size of the grating steel in special areas. The distance between the racks is increased, and the leading small ducts are encrypted to strengthen the initial support.
a.4 Strengthen the measurement of the excavation surface: after the initial support of the excavation, measure the subsidence of the vault and the convergence of the arch feet and walls, measure the tunnel uplift, and measure the grid steel frame Internal force measurement, systematic analysis of data, and immediate strengthening measures if any abnormalities are found.
b. Safety measures for electricity use at construction sites
Temporary use of electricity at construction sites must be strictly implemented in accordance with relevant regulations.
b.1 The installation, maintenance, and dismantling of temporary power lines must be completed by electricians who have received training and obtained employment certificates. Non-electricians are not allowed to perform electrical work.
b.2 Cable lines should adopt the "three-phase five-wire" wiring method. Electrical equipment and electrical lines must be well insulated. The suspension height and line spacing of power lines erected in the site comply with safety regulations, and they must be erected parallel to each other. On a dedicated pole.
b.3 The transformer is equipped with a grounding protection device, and its grounding resistance must not be greater than 4Ω. The transformer is fenced, has a locked door, is managed by dedicated personnel, and a warning sign "High voltage electricity is dangerous, do not approach" is hung. .
b.4 There must be insulating pads in front of indoor power distribution cabinets and distribution boxes, and leakage protection devices must be installed.
b.5 The metal shells of various electrical switches and equipment are equipped with grounding or zero protection. It is strictly forbidden to use other metal wires instead of fuse wires.
b.6 Fire-proof and electricity-proof distribution box, no debris should be stored in the box, the door should be locked, and the box should be managed by dedicated personnel.
b.7 Rubber cables should be used for the power supply lines of mobile electrical equipment. When passing through the driveway in the site, they should be laid underground through pipes. Damaged cables must not be used.
b.8 When overhauling electrical equipment, the power must be cut off. A warning sign saying "Someone is operating, closing is strictly prohibited" should be hung on the power box or switch handle, or a special person should be placed under supervision. Approval from relevant departments must be obtained when working with electricity on.
b.9 Bare wires are not allowed for power lines erected on site. Temporarily laid power lines are not allowed to be hung on steel formwork and scaffolding, and insulating supports must be installed.
b.10 Handheld lights used at construction sites use a safe voltage of 36V, while lights used in wet foundation pits and cavern excavations use 12V voltage.
17. Environmental protection and water and soil protection measures
In accordance with the requirements of the environmental management system standards, establish a team with the engineering captain as the team leader, the engineering deputy captain and the chief engineer as the deputy team leaders, and relevant A construction environmental protection agency in which department heads participate. The engineering team is equipped with full-time environmental engineers and part-time environmental personnel.
Make specific arrangements and corresponding measures for construction environmental protection and soil and water conservation before construction to ensure construction environmental protection goals.
During construction, production and living areas are arranged in a centralized manner, and corresponding preventive measures are formulated for the types of pollution that may be generated. Production and domestic waste are stored and processed in a centralized manner to achieve centralized control and reduce the scope of pollution. .
Strengthen inspection and monitoring, strengthen monitoring, monitoring and inspection management of dust, noise, vibration, exhaust gas and strong light at the construction site, and regularly organize relevant personnel to assess environmental protection work.
After the completion of the project construction, the construction site will be cleaned up in a timely manner, abandoned temporary facilities will be dismantled, excess materials and construction waste will be removed from the site, and the site will be cleared until the completion of the work.
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