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Second, the construction principle

Before construction, the weak surrounding rock should be carefully investigated, the design intention should be deeply understood, and a feasible construction scheme should be worked out according to different geological conditions. In the construction, the principles of "emphasizing geology, conduit, strict grouting, short footage, strong support, diligent measurement and early closure" are strictly followed, and the relevant regulations of tunnel construction are strictly implemented.

Third, the construction technology and construction scheme

Full-face method is used for the construction of Class III surrounding rock of tunnel, and bench method is used for the excavation of Class IV and V surrounding rock. The initial support adopts anchor, net and shotcrete, the inverted arch is advanced, the arch wall is lined once, the arch wall full-ring grid steel frame and the double-layer φ42 small conduit in the arch are used for the seismic fortification lining section of the active fault zone, and the lining trolley is used for the tunnel lining.

In the process of construction, advance geological prediction of tunnel, deepening blast hole detection, infrared detection method and advance geological confirmation are carried out to see if there are design differences. Advanced horizontal drilling should be used in key geological dangerous areas mentioned in the drawings, and the settlement observation should be carefully measured and analyzed.

Four, the hole excavation and support

The new Austrian tunneling method is adopted for the excavation of the cave body.

The V-class surrounding rock section is excavated in three steps and seven steps. The shallow buried section of Grade V surrounding rock is located at the entrance of tunnel, with advanced geological prediction, short footage, weak blasting, early closure and frequent measurement to ensure construction safety.

Construction process: advance conduit support → excavation of upper steps → initial spraying → installation of grid or steel frame → combined hollow anchor rod at arch → hanging net → re-spraying → excavation of middle steps → initial spraying → side wall grid steel frame → hanging net → side wall radial anchor rod → re-spraying → excavation of lower steps → initial spraying → side wall grid steel frame → hanging net → side wall radial anchor rod → re-spraying.

Ⅳ class surrounding rock section is excavated by arc guide bench method.

Advance conduit support → upper step excavation → initial spraying → installation of grille or steel frame → combined hollow anchor rod at arch → hanging net → re-spraying → lower step excavation → initial spraying → straight wall grille steel frame → radial anchor rod at side wall → re-spraying.

Bench excavation in the third-grade surrounding rock section.

Construction process: upper step excavation → initial spraying → combined hollow anchor rod at arch → hanging net → re-spraying → lower step excavation → initial spraying → radial anchor rod at side wall → re-spraying.

Construction of Grade Ⅴ, Ⅳ and Ⅴ Surrounding Rock by Step Method

Class Ⅳ and Ⅴ surrounding rocks are excavated by step method, the distance between upper and lower steps is not more than 1.5 times the excavation width, and the reserved settlement of vault is 5 ~ 10 cm (adjusted appropriately according to the measurement). The upper and lower steps are drilled by drilling rig, manual YT-28 rock drill, smooth blasting and non-electric millisecond detonator network initiation. In soft surrounding rock, excavator is used to cooperate with manual excavation. The lower steps are excavated and ballasted by excavators and loaders. During construction, the left and right steps are staggered by three meters.

Before drilling, measure the top line and center line of the inner rail, draw the excavation outline, and mark the hole position according to the design (adjust the drilling position appropriately when the geological conditions change). The diameter of drilling hole is φ42mm, the depth of upper bench cut and bottom hole is 1.4- 1.6m, and the depth of other holes is1.3m.: ; The depth of the lower step hole is 3.1m.

After drilling, check and make records according to the hole pattern, and re-drill holes that do not meet the requirements. Before charging, blow the mud and stone powder in the hole with high-pressure wind, check the hole and confirm that it meets the design requirements before charging. The charging shall be carried out in strict accordance with the design charging. After charging, all the blastholes are blocked with stemming. The peripheral eye is connected by interval charge and detonating cord, the cut eye adopts concentrated charge, the bottom is reinforced by 30% length, and the other eyes adopt concentrated charge.

The blasting network is initiated by millisecond detonator. Non-electric millisecond detonator is inserted into the cartridge and reversely loaded into the eye hole. The lead connection of nonel tube adopts grab type.

Six, mortar anchor construction

The anchor rod adopts 22mm threaded steel bar. Before construction, check whether the model, specification, quality and performance of the anchor rod meet the design. According to the anchor type, specifications and surrounding rock conditions, prepare drilling tools.

Pneumatic drill is used for drilling, and the spacing, depth and arrangement of holes meet the requirements of design parameters, and the direction is perpendicular to the rock stratum. The anchor rod is driven by a pneumatic mixer to rotate rapidly, and the anchor rod rotates and advances slowly.

In order to test the installation quality of the anchorage, the pull-out test of the anchorage is carried out as required, and the installation tension is timed. The line of action is concentric with the anchor and fixed firmly. Load evenly and slowly, stop drawing when reaching the design tonnage, and do not carry out destructive test.

Seven, advance small catheter construction

The small catheter is made of steel pipe, and the tip is closed at the front end, so that it can be inserted into the borehole smoothly. Plum blossom grouting holes are arranged on the pipe wall, the length of the tail grouting section is not less than 30 cm, and the extrapolation angle is 10- 15.

First, drill a hole with a pneumatic drill. The diameter of the opening is 50mm, and the sand and gravel are blown out with a blowpipe. Then push the small catheter into the hole with an impact pneumatic drill, or directly insert the steel pipe with a hammer. Finally, the periphery and orifice of the conduit are blocked with plastic mud, and the cracks in the working face are blocked at the same time. Grouting pressure is controlled at 0.5-65438±0.0 MPa. ..

Eight, steel production, installation and construction

Steel frame processing is carried out in steel bar processing plant according to different surrounding rock reserves.

After processing each unit steel frame according to the design, organize trial assembly, check whether the size and shape of the steel frame are qualified, and carry out structural tests 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, press according to the design load, and use steel bar stress meter and convergence instrument to detect the internal force and deformation of the steel frame. Strictly control the drilling size of the connecting plate.

The steel frame shall be installed after the initial shotcrete according to the design requirements, and the thickness of the shotcrete covered steel frame shall not be less than 4cm.

Nine, shotcrete construction

After the tunnel section is formed, shotcrete protection should be carried out in time. The spraying sequence is symmetrical from bottom to top. Spray the gap between the steel frame and surrounding rock first, then spray around the steel frame, and then spray between the steel frames. Sprayed concrete covers all lattice steel frames, and the thickness of protective layer is ≥2cm. Sprayed concrete is wet sprayed with wet spraying machine, the initial spraying thickness is 3cm, and then sprayed to the design thickness. Concrete is sprayed from both side walls by two wet spraying machine at the same time, so as to speed up the construction progress, and make the grid steel frame and sprayed concrete become an organic whole in time, which plays a supporting role.

Check the dimensions of excavation section before spraying. Remove pumice on the excavation surface and stone slag and deposits in corners. Treat the rock surface, remove obstacles, repair and chisel out the under-excavated part, and set up a working platform if necessary. Clean the sprayed surface with high-pressure air. A conduit is buried at the dripping part of the spray surface for drainage, and a blind ditch can be set for drainage in the aquifer with poor water guiding effect, and a drain can be set for drainage in the dripping part. Bury signs and control the thickness of concrete. There is good ventilation and adequate lighting. Before spraying operation, mechanical equipment, wind, water pipeline and circuit shall be thoroughly inspected and put into trial operation.

According to the mix proportion of wet sprayed concrete provided by the central laboratory, the mixing is completed once in the mixing station, and the slump is kept at 5 ~ 8 cm. Before the mixture is transported to wet spraying machine by concrete tanker, the liquid accelerator is added from the nozzle through wet spraying machine and sprayed on the sprayed surface.

The spraying operation is carried out in stages, and the spraying order is from bottom to top; It shall be repainted after the final setting of the previous layer of concrete. At the beginning of spraying operation, supply gas first, then start the machine, then feed, and at the end, stop the material first and then stop the gas. The material supply of the jet is continuous and uniform. When the machine is running normally, keep enough materials in the hopper, and control the working air pressure of the ejector at 0.45 ~ 0.7 MPa. When the spraying operation is finished or interrupted for some reason, the accumulated materials in the spraying machine and the conveying pipeline should be cleaned up.

The spray hand always keeps the nozzle perpendicular to the sprayed surface with a distance of 0.6 ~ 1.0m, and at the same time controls the smoothness of the concrete surface. Two hours after the final setting of sprayed concrete, water shall be sprayed for curing, and the curing time shall not be less than 7 days.

X. Inverted arch and filling construction

During construction, the inverted arch should be closed as soon as possible to facilitate the overall stress of the lining structure.

Inverted arch shall be poured in sections, and the excavation of inverted arch shall be controlled at 3m per section, and the length of each section shall be 5~ 10m. Before concrete pouring, the empty ballast and accumulated water at the bottom of the inverted arch should be cleaned up, and the concrete can be poured only after the steel bar binding is inspected by the supervision engineer. When pouring inverted arch concrete, it shall be carried out symmetrically from the center of inverted arch to both sides. Concrete pouring shall be transported by tank car, the radian of inverted arch shall be strictly controlled, and inverted arch and inverted arch shall be poured separately.

After the inverted arch concrete reaches the design strength, concrete shall be poured. Before pouring concrete, remove impurities, dust and water on the surface of the inverted arch.

In the inverted arch construction, in order to realize the parallel operation of excavation and lining, a trestle is erected on the inverted arch working face to ensure the normal running of all kinds of working vehicles without damaging the newly poured inverted arch concrete.

XI。 Waterproof and drainage construction of structure

A composite waterproof board is arranged on the arch wall between the tunnel lining sprayed concrete and the molding lining concrete. A blind ditch is set every 8m, and a φ50mm soft permeable pipe is set around it. During construction, the setting of circumferential blind pipes can be adjusted according to the water outlet situation of the tunnel, and centralized water outlet points should be set. φ 100 longitudinal permeable blind pipe is set at the lower part of the side walls on both sides, and the drainage pipe is wrapped with perforated corrugated pipe.

Before waterproof board construction, the tunnel clearance should be measured and checked, and the clearance requirements should meet the excavation contour line of tunnel design. It is required that the base surface should be smooth, without obvious concave and convex ups and downs, and without sharp protrusions such as steel bars and protruding pipe fittings, otherwise it will be cut off, and the cut-off part should be rounded with mortar to avoid puncturing the waterproof layer.

When laying waterproof board, the longitudinal center line of the tunnel should be correctly marked at the top of the shotcrete tunnel, and then the center line of the cut non-woven fabric should overlap with the center line mark on the shotcrete and be laid from the vault to both sides.

The waterproof board is laid without nails. Firstly, the longitudinal center line of the tunnel is correctly marked on the non-woven fabric of the tunnel vault, and then the center of the waterproof board coincides with this mark. Like non-woven fabrics, they are hung and laid from the arch to both sides, and welded with gaskets during laying.

The waterproof board shall be welded by a hot-sealing machine, with a lap length of 15cm, and the seam shall be welded on both sides, leaving a cavity in the middle for inspection.

After the waterproof layer is completed, concrete should be poured in time for protection.

XII. Tunnel Lining Construction

Tunnel lining adopts combined steel formwork lining trolley. The bench is made of I-beam, and the counterpart support is made of steel pipe. Template adopts special composite steel template.

After the excavation and support of the tunnel body is completed, the displacement rate shown by various test items after construction monitoring has obviously slowed down and has basically stabilized; The generated displacement has reached 80% ~ 90% of the predicted displacement; When the horizontal convergence rate (near the arch foot) is less than 0.2mm/d or the vault subsidence rate is less than 0. 15mm/d, the side wall and arch lining construction will be carried out. When the supporting deformation is large, it is difficult to strengthen the supporting capacity, and the deformation has no obvious convergence trend, the secondary lining should be constructed in advance after being reported to the supervision engineer for approval.

Concrete shall be poured symmetrically on both sides at the same time, and the uniformity of pumping concrete on both sides shall be controlled, and the elevation difference of pouring concrete on both sides shall not exceed 50 cm.

Before each cycle of lining, the concrete at the joints of the previous group of lining should be chiseled and cleaned, and a layer of cement slurry should be brushed to make the new and old concrete combine well.

After the continuous pouring of concrete is completed once, in case of power failure and other accidents, the pouring surface should be leveled and vibrated. Stop work for more than 2 hours, and wait for 24 hours before receiving washing.

When the vault is capped, it must be filled and compacted, leaving no gaps.

According to the humidity in the cave, water spraying or natural curing is adopted. Demolition should be carried out after the concrete in the arch reaches the design strength, and attention should be paid to the protection of the angle and surface of the concrete formwork during formwork removal.

Thirteen. Construction survey, monitoring survey and geological advance prediction

Tunnel survey shall be managed at different levels, and a precision survey team and a construction survey team headed by a full-time survey engineer shall be established to be responsible for their respective functions and powers. Strictly abide by the provisions of the railway engineering survey specification to ensure the measurement accuracy. The construction survey grade and accuracy standard of this bid section shall be implemented according to the specified requirements.

Before construction, retest and hand over the ground control piles delivered by the design unit; Joint survey between adjacent blocks; The entrance and exit of the tunnel should be jointly measured, and the traverse control network should be laid to control the centerline and elevation of the tunnel.

Control survey outside the cave: Total station is used for control survey outside the cave. Strengthen the contact and coordination with the line in the process of measurement to ensure that the through measurement is correct.

In-tunnel control survey: Total station is used for precise control survey in tunnel centerline survey, and in-tunnel control network adjustment and centerline adjustment are carried out in time.

The precision survey team of the project management department is responsible for the control survey, phased control survey and recheck inspection of the tunnel, recheck and guide the construction survey team of the tunnel construction team to complete the construction survey task, and be responsible for the on-site intersection, pile delivery, survey data and results of the construction survey team. Responsible for controlling pile protection survey and protecting all triangle points, leveling points and control points within the scope of the project.

The construction survey group of the tunnel team is responsible for the daily construction survey, construction lofting and control of the embedding and protection of pile points in the project site.

During engineering construction, the center line and elevation should be measured according to the design drawings to ensure the accuracy of the center line and elevation. After the completion of the project, the whole line shall be measured in time, overlapped and closed, and the measurement data shall be submitted to the supervision engineer. The original measurement records, data, calculations and charts shall be true and complete, and shall be properly kept by special personnel.

Seriously implement the measurement review system, the field measurement data must be reviewed by a second person, and the indoor measurement results must be independently calculated by two people and verified by each other before delivery. It is strictly forbidden to use data that has not been checked and confirmed by a second person.

Fourteen Monitoring and measurement

Field monitoring is one of the core technologies in the design and construction of NATM composite lining. During the construction, a detailed monitoring and measurement plan should be made, and a full-time measurement team should be set up to be responsible for the daily work of measuring point embedding, monitoring and measurement, data processing and analysis, instrument maintenance, etc., to ensure the reliability of measurement data, provide accurate basis for construction and design, and ensure the safety, quality and investment of construction.

A. Purpose of measurement

A. 1 master the surrounding rock dynamics and control the surrounding rock deformation during construction.

A.2 Understand the function of supporting structure, and take timely measures to ensure safe construction.

A.3 Provide a basis for optimizing the design and ensure that the tunnel is stable and economical.

B. Monitoring and measurement projects

Deformation measurement, stress and strain measurement, surrounding rock stability and supporting effect analysis of tunnel surrounding rock.

C. observation of engineering geology and supporting conditions

C. 1 Observation contents: after the tunnel excavation, the self-stability, geology and rock quality of the excavation surface and its surroundings, check the classification of surrounding rocks, draw geological sketches, and check whether the structural conditions of the initial support (anchor rod, shotcrete and steel support) are damaged.

The observation of excavation surface should be carried out after each blasting, especially under the condition of weak surrounding rock. Geological survey should be carried out immediately after excavation. In case of special instability, a special person shall be assigned for uninterrupted observation. Make records after observation, and organize and save them.

D. Tunnel clearance convergence measurement

Clearance change measurement and vault subsidence measurement are carried out on the same section in principle. The measured section spacing is related to many factors such as tunnel length, surrounding rock conditions and excavation methods.

There are two horizontal baselines in the general section of clearance change measurement, and four baselines in the section with buried depth less than 2 times the excavation width and the section with expansion or eccentric pressure.

Key points of measurement: fix the short rod of the gap displacement meter in the rock mass of two points to be measured; Determine the measuring distance according to the surrounding rock conditions; Measurement accuracy: generally 0. 1mm in the case of small changes, and 1mm in the case of large changes.

E. vault subsidence measurement

The measuring points of vault subsidence are generally arranged in the arch and on both sides of the arch waist, and three measuring points are arranged on each section. When affected by ventilation pipes or other obstacles, the position can be moved appropriately.

F. Measurement of surrounding rock displacement and anchor strength

According to the surrounding rock conditions and engineering importance, 2 ~ 5 measuring points are set for each section.

G. stress and strain measurement of tunnel steel arch frame

The stress and strain measurement of tunnel steel arch adopts a stress box which can support the yield strength and is placed under the bottom plate supported by steel arch. In the stratum with extrusion force or expansion force, when using the inverted arch cross brace, the stress box is placed on the special arch frame.

Measure the stress in the lining concrete, arrange several pairs of stress boxes (one radial and one tangential) on the measuring section, and then read the measuring pipeline centrally.

Stress-strain measurement on the anchor, the pressure box is placed on the anchor to form an enlarged washer, which can directly measure the stress value added to the rock mass.

H. The measuring frequency mainly depends on the displacement rate and the distance between the measuring point and the excavation face, and is generally selected according to the following table, that is, the measuring frequency at the initial stage of original burial should be 1 ~ 3 times/day. As the surrounding rock becomes more and more stable, the measurement frequency can be reduced, and when there are signs of instability, the measurement frequency should be increased.

When the surrounding rock is basically stable, the measurement shall be carried out at the frequency of 1 time /3 days for 2 weeks. If there is no obvious deformation, the measurement can be ended.

Fourteen Geological advance prediction

Geological advance prediction is one of the important means to determine the change of surrounding rock, especially in tunnel construction, especially in bad geological sections. A comprehensive advanced geological prediction system of geological advanced prediction and advanced drilling exploration was established in the construction. TSP203 geological advanced predictor, HY303 infrared water detector, horizontal geological drilling rig and other instruments and equipment were used to accurately predict the geological conditions ahead and provide reliable technical parameters for the construction.

Regularly predict the engineering geology, hydrogeology and surrounding rock types in front of the tunnel excavation face, and formulate feasible construction methods and construction precautions according to the prediction results. After excavation, the prediction results are analyzed and compared, and summarized continuously to gradually improve the accuracy of geological prediction ahead.

Fifteen, quality assurance measures

In strict accordance with the design of smooth blasting, we should arrange holes and charge, determine the excavation section, check the blasting effect, revise the blasting design, strive to improve the quality of smooth blasting and effectively control the excavation section.

Establish a monitoring and measuring team, equipped with special measuring instruments, measure regularly according to regulations, collect data accurately and completely, analyze and master the convergence of surrounding rock, and feed back information in time, so as to provide scientific basis for design and construction.

Strive to improve the quality of bolting and shotcreting support, check the pullout force of anchor rod and the thickness of bolting and shotcreting layer according to regulations to ensure that the section size meets the design and the supporting structure is stable and reliable.

The tunnel should be equipped with soft permeable blind ditches in the circumferential direction and longitudinal direction according to the design requirements, so as to ensure the performance of waterproof materials and meet the design standards during construction. When laying, it must be close to the sprayed concrete surface to ensure the lap length. The tunnel lining is assembled with fixed steel formwork. First, the design, and then the trial before lining. In the process of construction, accurate measurement is carried out to ensure that the formwork joints have the neat appearance effect of longitudinal lines and circumferential surfaces.

The overbreak part of the tunnel shall be backfilled and compacted with concrete of the same grade in strict accordance with the specification requirements.

Construction quality assurance measures in rainy season:

Before the rainy season construction, do a good job in rainy season protection measures, establish flood control organizations, prepare sufficient flood control materials, and make various preparations for flood fighting and emergency rescue.

During the rainy season construction, someone will be responsible for the weather forecast and deliver the rain in time. According to the weather trend forecast, arrange the working procedure reasonably and do the protection work well in advance.

Technical measures to ensure tunnel impermeability, leakage prevention and crack prevention;

Do a good job in tunnel waterproof and drainage. Ensure the 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 cracks in the secondary lining. During the tunnel construction and operation, the quantity and direction of groundwater may change. There is no guarantee that there will be no water accumulation or less water accumulation during construction, and the waterproof board itself has good waterproof performance, but it is often damaged by pouring the secondary lining during construction, which affects the waterproof effect. Therefore, we must not despise the application of waterproof layer or ignore the construction quality because of temporary water shortage.

The back of primary support and secondary lining must be backfilled and compacted. Foreign bodies or cavities shall not be backfilled after initial support. When necessary, grouting should be carried out for many times until it is dense. In order to prevent the secondary lining from being stressed too much, we should strengthen monitoring and measurement, adjust the construction support parameters according to the measurement results, and determine the construction time of the secondary lining.

Make expansion joints according to design requirements. Expansion joints must be vertical and straight, and there can be no dislocation and bite. The water stop at the expansion joint shall be set as required. In order to reduce the construction joints of secondary lining, continuous grouting must be carried out during secondary lining. When it is necessary to stop, the water stop must be set according to the design requirements. For unfavorable geological conditions, such as when the tunnel passes through faults and broken zones, the tunnel lining structure should be strengthened according to the design.

In order to avoid the secondary lining cracking due to the basement sinking, before the secondary lining construction, the side wall foundation must be cleaned before the formwork can be placed. Admixtures and admixtures, concrete with low water cement ratio and high fly ash content are also used to prevent lining cracking. Choosing cement type, concrete coarse and fine aggregate and construction water in concrete construction are also the main technical measures to solve the tunnel cracking problem. Do a good job in the maintenance of secondary lining concrete to ensure the quality of concrete.

Cement is piled up in the canopy, with wooden pillows or squares at the bottom and waterproof ponchos to avoid being affected with damp. All materials and machinery should be placed in a higher place, if necessary, tarpaulins should be supported to prevent rain, and water retaining and drainage facilities should be set on the ground.

Improve the standard of construction access road to prevent the access road from blocking the entry of materials and the passage of construction machinery in rainy season.

XVI. Safety measures

Workers who take part in tunnel construction must receive safety technical education, be familiar with and abide by the technical safety specifications for tunnel construction, take safety examinations, and only after passing the examinations can they operate at their posts and wear safety protection articles as required. All kinds of mechanical operators must hold relevant certificates, and all kinds of machines 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. Those who seriously violate the construction safety regulations have the right to order them to stop work and make rectification until they pass the re-inspection. Once an accident occurs, it should be handled in strict accordance with the "three-no-pass" method.

A. Construction safety measures

A. 1 Adhere to the principle of taking geology as the guide, keep abreast of the previous geological conditions, and adopt special advance support and initial support measures for abnormal geology.

A.2 Adhere to the principle of roof protection first and then excavation, and organize construction: adopt pre-grouting reinforcement measures with advanced small pipes. Through experiments, the grouting pressure and consolidation range are determined, so that the grouting bodies can bond with each other and the stability of surrounding rock itself can be improved.

A.3 Strictly control the footage of each cycle, carry out initial support in time after excavation and molding, ensure the convergence of working procedures, construct inverted arch into a ring as soon as possible, improve the stress condition, narrow the spacing between grid steel frames in special areas, and strengthen initial support by encrypting leading small pipes.

A.4 Strengthen the measurement of excavation surface: after the initial support of excavation, measure the vault subsidence, the convergence of arch foot and wall, the tunnel uplift measurement and the internal force measurement of grid steel frame, systematically analyze the data, and take reinforcement measures immediately if any abnormality is found.

B. Safety measures for electricity consumption at the construction site

Temporary power consumption on the construction site shall be strictly implemented in accordance with relevant regulations.

B. 1 Temporary power lines shall be installed, maintained and dismantled by trained electricians who have obtained the work license, and electricians are not allowed to carry out electrician operations.

B.2 Cable shall be connected in tn-s mode, and electrical equipment and lines must be well insulated. The suspension height and line spacing of power lines erected in the field should meet the safety requirements and be installed on special poles.

B.3 The transformer shall be equipped with grounding protection device, and its grounding resistance shall not be greater than 4Ω. The transformer should be fenced, the door should be locked, managed by special personnel, and a warning sign "Do not approach high voltage" should be hung.

B.4 Insulating pads should be set in front of indoor power distribution cabinets and distribution boxes, and leakage protection devices should be installed.

B.5 The metal shell of all kinds of electrical switches and equipment shall be protected by grounding or zero connection. It is forbidden to use other metal wires instead of fuses.

B.6 There shall be no sundries in the fire-proof and electricity-proof distribution box, and the door of the box shall be locked and managed by special personnel.

B.7 rubber cables shall be used for power supply lines of mobile electrical equipment. When crossing the driveway of the stadium, it should be buried through pipelines. Do not use damaged cables.

B.8 When overhauling electrical equipment, the power supply must be cut off, and a warning sign "No switching on" should be hung on the power box or switch handle, or someone should be appointed to take care of it. Live working must be approved by relevant departments.

B.9 bare wires shall not be used for power lines erected on site, and temporary power lines shall not be hung on steel formwork and scaffolding, and insulating supports must be installed.

B. 10 safe voltage 36V is used for hand-held lighting in the construction site, and 12V is used for lighting in wet foundation pit and cavern excavation.

Seventeen, environmental protection and water and soil protection measures

According to the requirements of environmental management system standards, a construction environmental protection organization was established, with the project captain as the team leader, the deputy team leader and chief engineer as the deputy team leader, and the heads of relevant departments as participants. The engineering team is equipped with full-time environmental protection engineers and part-time environmental protection personnel.

Before construction, formulate specific arrangements and corresponding measures for construction environmental protection and soil and water conservation to ensure the environmental protection objectives of construction.

During the construction process, the production and living quarters will be arranged centrally, and corresponding preventive measures will be formulated according to the possible pollution types, and the production and living garbage will be stored and treated centrally, so as to achieve the purpose of centralized control and reduce the pollution range.

Strengthen inspection and monitoring, strengthen the monitoring, monitoring and inspection management of dust, noise, vibration, waste gas and strong light on the construction site, and organize relevant personnel to evaluate environmental protection work on a regular basis.

After the project construction, the construction site should be cleaned up in time, abandoned temporary facilities should be dismantled, and excess materials and construction waste should be removed from the site, so that the site can be cleaned up after work.

The material comes from the network, edited and arranged: Luqiao network.

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