The calculated span of rigid tied arch with middle hole is L=42m, the rising height f=7.0m, the span ratio D= 1/6, and the arch axis is a quadratic parabola. The tie beam adopts I-shaped cross section, with a height of 1.4m, a wing width of 0.8m, a wing thickness of 0.25 and a rib thickness of 0.3, and gradually becomes a rectangular cross section with a width of 0.8m and a height of 1.4 at the arch foot; The arch rib adopts I-shaped section, with a height of 1.3m, a wing width of 0.8m, a wing thickness of 0.25 and a rib thickness of 0.4, and gradually becomes a rectangular section with a width of 0.8m and a height of 1.3 at the span of 1/3; The suspenders are made of 48φs5 high-strength carbon steel wires with a spacing of 4.2m The whole bridge is 2×9 suspenders with a circular cross-section diameter of 245mm. Beams are set at the corresponding suspenders, and the carriageway slabs are placed on the beams.

Second, the main construction steps and main technical measures of the middle hole

1. Drive bracket pile foundation, erect tie beam and beam bracket, reserve navigation hole, tie tie beam, arch foot and end beam reinforcement, and pour tie beam, arch foot and end beam concrete with formwork.

1, support foundation treatment:

A, tie bar support foundation:

The mid-span bridge span is located in the water and is arranged in three spans. Six φ273 steel pipe piles with a length of 15m are used under the mid-span pier, and the wall thickness is 7 mm The buried depth of steel pipe piles is determined according to calculation, and the bearing capacity can be controlled according to penetration. Steel caps are adopted, and a group of double-layer and three-row Bailey piers are used as piers, and sand tubes are placed on the piers. On both sides of the span, 10m long round wooden stakes are used, and 18cm*20cm long wooden Fang is placed on the stakes.

B, beam supporting foundation:

Under the mid-span beam, six φ273 steel pipe piles are inserted into the tie-bar temporary support, and the steel structure arrangement at the top of the piles is the same as that of the tie-bar support; Six round piles with a length of 10m are used under the side span beam.

2, stent erection:

According to the structural calculation, single-layer, three-row and 27m truss Bailey longitudinal beams are adopted under each root beam in the span, and reinforcing chords are arranged up and down. On the Bailey longitudinal beam, a layer of 20CM* 18CM wood square and a layer of 10 cm wood fang and channel steel are laid with a transverse spacing of 75CM. Put a small wooden square of 15CM* 18CM near the anchor hole of the suspender at the lower part of the tie beam, with a cushion height of 50CM. After the tie beam is poured, pull out the small wood square to ensure that the anchor hole of the boom has a certain operating width. Tie beam support. The beam support also adopts three rows of Bailey longitudinal beams, and there are reinforcing chords at the top and bottom, which are connected with Bailey longitudinal beams under tie beams through support frames. I20 I-beam is laid on Bailey longitudinal beam under the beam, and leveled at the bottom die of tie beam. . The side span adopts φ48 steel pipe, with vertical spacing of 75cm and horizontal spacing of 60cm, and the lower end of the vertical rod is supported on the wooden Fang.

3. Reservation of navigation holes:

When scaffolding is erected, navigation holes should be reserved according to the design regulations, and their width and clear height should meet the requirements. Two φ60cm steel pipe piles are laid on both sides of the navigation hole. Considering the design elevation of bridge beam bottom and the height of bearing, the navigation slope of ships passing through the bridge site should be limited to ensure the safety of bearing.

4, binding beam, end beam, arch foot formwork system, steel bar system, steel strand bundle and beam, embedded parts placed.

A, in order to ensure the real light inside the tie beam concrete, the tie beam bottom formwork and side formwork shall be made of high-quality bamboo veneer, and the formwork shall be fixed with pin bolts, and the strength and rigidity of the formwork shall meet the requirements. The tie beam end formwork is made of wood formwork, and a set of tie beam formwork is planned to be processed in sections, and sponge strips are sandwiched at the joints of the formwork to ensure tight joints and no slurry leakage. The end beam formwork also adopts high-quality bamboo veneer, wood square and channel steel as stiffening ribs.

B, laying a tie rod bottom die on the bracket. According to the design drawings, the pre-camber of tie beam is calculated as 2.5cm according to the design requirements, and the pre-camber of construction is distributed according to quadratic parabola. In addition, preloading the tie bar bottom die with equal load sand bag can eliminate the inelastic deformation caused by node pins on the one hand, and it can be considered that the deformation of scaffolding is mainly caused by the elastic deformation of Bailey frame on the other hand. The elastic deformation value can be determined according to the deformation of three rows of Bailey beams with the same span erected on land under the tie beam load. When laying tie beam bottom formwork, this deformation should be considered according to quadratic parabola. After preloading, it is necessary to measure whether the elevation of each control point meets the design.

C, steel binding welding molding at the scene, welding and binding joint should comply with the specifications and design requirements. Every 50-60 cm, the steel strand is bound with lead wire, welded with the pipeline positioning rib, passed through the corrugated pipe, first erected the side formwork, then passed through the steel strand bundle, then erected the side formwork, put the tie beam, cross beam anchor pad and cross beam corrugated pipe, and finally erected the end formwork. In order to prevent slurry leakage, a sponge strip should be clamped at the joint between the side formwork and the bottom formwork to prevent slurry leakage.

D, pay attention to put the following embedded parts in the construction process:

(1) Tie the beam and anchor pad at the tensioning end of the beam;

(2) arranging 3-4 slurry discharge holes at equal intervals along the axis of the tie beam prestressed beam pipeline;

(3) The anchor pad and downcomer at the fixed end of the derrick are welded on the tie beam reinforcement and anchored on the formwork, and their plane position and verticality are accurately measured before and after concrete pouring.

(4) Reinforced embedded parts, corrugated pipes and anchor pads in the beam.

⑤ When there is a fight in steel binding, follow the principle that ordinary steel bars are used as prestressed steel bars and small steel bars are used as big steel bars.

E, tie beam and end beam casting process

Tie beam concrete is poured first, and then end beam concrete is poured. In order to ensure the compactness of tie beam concrete, internal vibrator is used for vibration. After the tie beam and the end beam are removed, the tie beam shall be roughened at the corresponding middle beam position. Concrete pouring shall be carried out in a whole block, obliquely layered and longitudinally segmented, with the segmented length controlled at 4-6m and the layered thickness less than 30cm, which is roughly divided into four layers. Attached vibrator and plug-in vibrator are used for combined vibration, and pouring shall be carried out continuously and evenly. HB-30 pump is used for concrete transportation.

Due to the high and narrow tie beam section, dense steel bars, embedded parts and corrugated pipes criss-crossing, according to previous engineering construction experience, medium and small sizes of continuous grading are adopted, and multifunctional composite admixture (JM-II type) with retarding, slump-retaining, water-reducing and Gao Zengqiang properties is added to concrete (the dosage is 1. 1% of cement dosage), which not only meets the slump of concrete, but also meets the requirements of concrete. After the initial setting of tie beam or end beam concrete, the prestressed steel strand bundle will be dragged left and right several times with a single-wheel hoist to prevent the mortar infiltrated along the bellows from sticking to the steel strand bundle. Wrap the exposed steel strand to the anchor plate mouth with snakeskin cloth to prevent rainwater from entering the corrugated pipe and prevent the steel strand from rusting.

F, in the process of concrete pouring, should do the following work:

(1), casting is symmetrical and balanced, and observation points are set on the basis of the support to monitor the support settlement at any time.

(2), assign personnel to track and observe the deformation of formwork and support.

(3) The reinforcement at the arch foot is very dense, so a special mixture ratio of fine stone concrete is designed at the arch foot at the beam end. In addition to attached vibrators and plug-in vibrators, clamp vibrators are used to strengthen vibration to ensure the compactness of concrete;

(4) The embedded parts at the arch foot and suspender shall be positioned and firmly connected with steel bars to prevent displacement during pouring.

Second, tie beam the first batch of prestressed beam tension:

According to the design requirements, when the tie beam concrete strength reaches 90% of the design strength, the tie beam N 1 and N2 steel beam are tensioned, and the tension control stress is σk=0.75Ryb, with two YCW-250 jacks and oil pump ZB4/500. Tension at both ends is controlled by tension and elongation, and the difference between actual elongation and theoretical elongation is controlled at 6%. Tie beam anchorage is a clip-on self-anchored anchorage. According to Technical Code for Construction of Highway Bridges and Culverts (JTJ04 1-2000), the tensioning procedure of prestressed beam is: 0 → initial stress → σ con (anchorage with load for 2min). The tensioning sequence of prestressed tendons meets the design requirements, and the tensioning process of OVM anchor is as follows:

A, jack and accessories device sequence:

Install working anchor plate → clip → limit plate → jack → tool anchor → tool anchor clip.

B, prestress:

Fill the jack tensioning cylinder to the designed oil pressure value → measure the elongation → make a tensioning record.

C, anchoring:

Open the cut-off valve of the high-pressure oil pump, and the tension oil pressure slowly drops to zero-→ the piston returns.

D, grouting:

Dismantle the tool anchor, jack and limit plate → remove excess steel strand → seal the anchor → grout.

Three, the first batch of prestressed tensioning end:

According to the requirements of the design drawings, two N2 prestressed steel beams at the bottom edge of the end beam are tensioned, and the tensioning control stress σk=0.75Ryb. Two YCW- 150 jacks (matching oil pump ZB4/500) are used in the prestress construction, and the tensioning process is the same as that of tie beams.

Four, arch rib bracket erection, arch rib, wind bracing formwork system, steel bar system.

A, arch rib installation bracket erection:

Scaffolding is arranged at the lower part of the arch rib. Considering the pouring of arch rib concrete and the construction of suspender tension operation surface, it is proposed to adopt steel pipe scaffold, which is set up at the lower part of the steel pipe foot assembly point of arch rib segment, with the distance between main rods of 60CM. Precisely release the plane position of the support, and at the same time, it can't interfere with the boom construction. The height and elevation of the bracket are really set out according to the standard of the lower edge seat of the arch rib, and the pre-camber is 2cm according to the design requirements. In order to strengthen the stability of arch rib bracket, cable wind rope is used to fix it outside the bracket. After the scaffold erection is completed, the center line of arch rib shall be set out at the top of the scaffold.

B, pouring arch rib, wind brace concrete:

Arch rib concrete is poured first, and then wind brace concrete is poured. In order to ensure the compactness of concrete, it is vibrated with an internal vibrator. Concrete pouring shall be done as a whole, obliquely layered and longitudinally segmented, with the segmented length controlled at 4-6m and the layered thickness not more than 30cm, which is roughly divided into four layers. After pouring a section of concrete, the top of arch rib is covered with bamboo veneer, vibrated by internal vibrator, and poured continuously and evenly. The concrete is transported by HB-30 pump.

(5), derrick installation, arch rib set up, forming a bare arch structure, concrete members to participate in the stress, derrick initial tension.

1, suspender installation, arch rib falling.

Install the steel sleeve of suspender and weld it with the embedded steel plate of arch rib and tie beam. After the strength of arch rib and wind bracing concrete meets the design requirements, the upper small bar supporting the arch rib is removed to form a bare arch structure. 50# fine stone concrete is poured in the steel casing of suspender.

2. The suspender φs5 high-strength steel wire is cut and bundled, and then cold heading.

A, steel wire blanking and bundling, as well as cold heading and threading.

Use straightener to finish cutting, straightening and blanking at one time. Blanking will be carried out under a certain tension. The steel wire bundle will be discharged by LD20k hydraulic cold heading machine. In the same bundle of steel wires, the relative difference of blanking length will be strictly controlled within 2mm. The blanking length of each messenger wire will be calculated according to the following formula:

L =1+2h+2δ-0.5 (h-h1)-δ l-c, where:

1- the length of the boom hole;

H—— thickness of bottom of anchor cup or thickness of anchor plate;

δ —— Upsetting allowance of steel wire.

H—— Height of anchor cup

H 1- nut thickness

△L—— tensile elongation value of steel wire bundle

C—— Elastic compression value of member concrete during tensioning.

Bundle weaving should be carried out on a flat ground, and each bundle should be arranged in a specified number. Comb boards are placed every 1- 1.5m, steel wires are embedded in the comb boards respectively, and then lead wires are woven into curtains in turn. Every 1- 1.5m, a short steel pipe with the same outer diameter as each bundle is placed, and the steel wires are folded and bundled into bundles.

B, piercing and cold heading

Firstly, cold heading is carried out with LD20k hydraulic cold heading machine. Upsets should be round and not skewed, and 3% of the total number of upsetting heads should be taken for tensile test. After the test heading is qualified, the heading should be officially upset, and the heading oil pressure should be the rated oil pressure of the heading device. In order to ensure that the upsetting head is not skewed, the end face of the steel wire to be upset should be perpendicular to the parent material, and the eccentricity of the upsetting head should not exceed1mm.

First, the steel wires (anchor rings have been removed) that have been inserted into the improved DM5A anchor holes one by one are cold-upset at the site, then the braided steel wire bundle is inserted into the steel pipe of the hanger from the upper end of the hanger, and the anchor rings are tightened at the lower end of the tie rod.

3. Initial tension of boom:

Tension of suspenders is the most critical process of bridge completion. The tension of suspenders must be carried out in strict accordance with the tension and sequence specified in the design. Use two YCW- 150 jacks (with tool tie rods and struts) to tension a steel beam corresponding to the arch rib suspender, and adopt the order of first crossing the middle and then crossing both sides. See Figure 5 for the boom tensioning assembly. The tensioning of each boom shall follow the following procedures:

0-→ initial stress -→ σ i 1 (anchorage with load for 2min),

σi 1 is the first control stress of each suspender, which is determined according to the design requirements. Double-control tensioning is adopted, and tensioning records are noted.

4, should do the following work in the process of tensioning:

A, make sure that the number of teeth screwed by the tool screw in the anchor cup at end A is greater than 10.

B, adjust the jack brace, pad, ensure that the center of the jack and the center of the steel wire bundle are on the same axis.

C, loading by stages, 2Mpa per stage.

D, tracking and measuring the camber value, horizontal displacement and elevation change of the arch rib on the tie bar.

Ensure that the end anchor pad is horizontal and perpendicular to the derrick axis.

(6) Formwork system, steel bar system, steel strand bundle, beam piercing, embedded parts and cast-in-place concrete in the beam.

Laying the bottom formwork of the middle beam on the arch beam bracket, making and installing steel bars, placing embedded parts at the same time, and then pouring concrete.

(7), tensioning the remaining end beam and intermediate beam prestressed reinforcement.

According to the requirements of the design drawings, the prestressed steel beams of the remaining end beams and the middle beams are tensioned, and the tensioning control stress is σk=0.75Ryb. Two YCW- 150 jacks (matching oil pump ZB4/500) are used for the prestressed construction, and the tensioning process is the same as that of tie beams. After all the prestressing tendons of the beam are tensioned, two carriageway slabs are installed on both sides of the near-tie beam with floating cranes.

(eight), the removal of temporary support.

(9) The second batch of prestressed tendons of tensioning tie bars shall be consolidated, grouted and anchored.

Use YCW—250 jack to tension the second batch of pre-stressed bars of tie rods. The tensioning sequence and tensioning sequence meet the design requirements, and the specific procedures are the same as those of the first batch of prestressed tendons. And then grouting and anchoring the prestressed channel.

(10) Laying middle hole carriageway slab and pouring hinged concrete.

On-site prefabrication of middle hole carriageway slab. When installing the carriageway slab, brush a layer of C40 cement mortar at the corresponding position of the crossbeam at the resting point of the carriageway slab. Pouring hinge joint concrete.

(1 1), tensioning boom

Use two YCW- 150 jacks to tension the derrick for the second time, and the tensioning process is the same as the first time. After the suspender is tensioned, 50# cement mortar shall be poured into the suspender steel pipe, and grouting shall be carried out from bottom to top. The fixed end is sealed with 50# micro-expansive concrete.

(14), paving the bridge deck, pouring the crash barrier.

30# waterproof concrete with 8cm thickness is poured in the middle hole, asphalt concrete with 7cm thickness is paved by paver, steel bars are bound, formwork is erected, and cast-in-place concrete crash barrier is used.

Third, some problems should be paid attention to in the construction of 42m tied arch in main tunnel.

According to our company's accumulated experience in previous construction, combined with the actual situation of this project, we should pay special attention to the following aspects in construction:

1. Steel Bailey should be used as far as possible for the erection of lower support to eliminate inelastic deformation of support nodes.

2, choose high-quality anchorage and strict testing, calibration jack and oil pump. After the concrete reaches the specified strength, it can be tensioned. When tensioning, strictly control the tension and check the elongation value. During construction, pay attention to the camber value and compression value of the component and compare them with the theoretical value.

3. The construction must be symmetrical, and unilateral loading is strictly prohibited.

A, tie beam, cross beam and arch rib concrete are poured symmetrically from both ends to the middle of the span to ensure uniform and minimum bracket deformation.

B, paving the carriageway slabs from both ends of the span to the middle in turn, and pouring the bridge deck pavement in this order.

4. After the installation of the lower bracket and the arch rib mounting bracket is completed, the plane layout, top elevation, node connection and vertical and horizontal stability shall be comprehensively inspected, and the next working procedure can be carried out only after passing the inspection.

5. Because the blanking requirement of high-strength steel wire is very strict, the actual length of each boom should be measured again before blanking to determine the blanking length. The tension of the suspender must be loaded symmetrically step by step, in batches and at multiple points. After the first and second tensioning, the internal force of the suspender must be adjusted several times.

Fourth, the project quality assurance measures

1. Establish a quality management network headed by the project manager and in charge of the chief engineer, define the quality assurance plan, quality objectives and policies, implement ISO9000 international quality standards, actively carry out total quality management, carry out quality management activities for all employees and the whole process, continuously improve and improve the quality through PDCA cycle, carry out construction in strict accordance with specifications and design requirements, and carry out construction in strict accordance with the construction technical scheme.

2. Strictly implement the on-site inspection system, give the quality inspector the right of "one-vote quality veto", implement dynamic management, pay attention to process control, put prevention first, set up quality management points for key parts, key processes and special processes, prepare work instructions, and clarify standards and responsibilities. The next working procedure can only be carried out after each working procedure has passed the inspection by full-time quality inspectors and supervisors.

1, establish and improve the system of blue prints.the design, step by step technical disclosure system, material approach inspection system and quality analysis notification system, and strictly abide by them to ensure the technical guarantee of construction.

2. Do a good job in self-inspection, mutual inspection, handover inspection and special inspection of the production team.

3, the project intends to establish a central laboratory and standard curing room, and equipped with professional testing personnel, according to the specification requirements for sampling inspection of raw materials, and according to various indicators, design a qualified mixture ratio to meet the needs of construction, undertake the inspection items specified in the specification, and provide necessary data for guiding construction. (Provide specific time such as form removal and frame falling. ).

4, raw materials must undergo strict inspection and material test, qualified rear can play, cement, steel and so on must have a warranty.

5, prestressed corrugated pipe installation position must be accurate, binding is firm, when the anchor plate is installed, its plane and channel axis must be vertical, concrete vibrating to dense, vibrator shall not touch the corrugated pipe.

6, jack, oil pressure gauge and other tensioning equipment and anchorage, must be checked one by one before use, after correction, must appoint someone to operate and maintain. Jack, pressure gauge, oil pump, etc. Before use, it must be calibrated by the measurement department, and it must be checked regularly during use. Prestressed tensioning shall be carried out after the strength of concrete reaches the strength specified in the design, and the tensioning process shall be double-controlled, and the original tensioning records shall be kept during tensioning.

When steel formwork is used, sponge strips are sandwiched at the joints to prevent slurry leakage, so as to ensure that the concrete matures at one time, the surface is smooth and flat, and the appearance is beautiful and solid.

7, beam hoisting, bracket unloading concrete strength must meet the specified requirements.

8. In strict accordance with the bridge axis, traverse points, pile numbers and leveling points provided by the supervision project, the total station, theodolite and level are used for survey lofting, and the survey control points of the whole line are jointly measured on a regular basis, and the results are analyzed and reported to the supervision engineer for approval, so as to make corrections.

9, the establishment of bridge engineering construction electricity reserves (with generators), in case of continuous pouring concrete quality defects or quality accidents caused by power failure.

10, focusing on quality assurance data management, filling in and filing construction quality assurance data in a timely and earnest manner.

Five, concrete quality assurance measures

1, raw material control:

The cement is made of high-quality 425# and 525# cement, Wuhu medium-coarse sand with reasonable gradation, hard texture and clean particles, Yixing middle school boy with excellent texture and reasonable gradation, and the mixing water is made of river water that has passed the inspection.

2. Before concrete construction, do a good job of mix design and trial mixing according to the specification requirements, ensure accurate ingredients and even mixing, and strictly control the water cement ratio, mix ratio and slump of concrete during construction. Concrete should be poured in layers and sections according to the order and direction of a certain thickness from bottom to top. The upper concrete must be poured before the initial setting of the lower concrete, vibrated and compacted, and covered and maintained by water spraying.

3. High-grade concrete adopts high-quality 525# cement and high-quality coarse and fine aggregate, and the sand and gravel are washed, with low water cement ratio, low sand ratio and suitable superplasticizer.

4.HZ-50B automatic mixing station is used for concrete mixing. Raw materials are measured by electronic scales, and mixing is forced by double horizontal axes. High metering accuracy and uniform mixing ensure the mixing quality of concrete.

5, concrete template joints with sponge, prevent slurry leakage, smooth surface, smooth, beautiful, solid outside.

6, concrete form removal to dismantle the non-bearing part, after the non-bearing part is removed, major complex template should have a form removal scheme.

Six, the construction technology guarantee measures

Creating a high-quality project is the guide for all the work of the whole project. In order to ensure that the whole project is technically guaranteed, the following systems must be implemented:

1, construction organization design approval system.

2, technical review, concealed engineering acceptance system.

3, technical quality disclosure system.

4, three-level acceptance and partial engineering quality evaluation system.

5. For key and difficult projects, invest construction management personnel, technicians and team backbones with similar engineering construction experience.

Seven, safety assurance measures

1, establish a safety management network, implement a three-level security responsibility system, and the project management department will set up a management leading group headed by the project manager; Project intends to set up a safety department, equipped with full-time security officer responsible for the safety management of the whole bridge; Each team shall have a part-time safety officer, who shall be responsible for the safety inspection and supervision of the construction site section, so as to make the responsibilities clear and check at all levels.

2. Adhere to the policy of "safety first, prevention first", give the safety officer "one-vote veto on safety", strengthen the regular safety education for employees, and make the safety work institutionalized and regular. Conduct comprehensive safety education and technical disclosure before construction to improve employees' awareness of self-prevention.

3. There are inspections and summaries during the construction process, and all construction records should be carefully made. Project intends to check regularly, full-time security officer classes supervision and inspection. Team safety personnel should check the site situation 10 minutes before going to work, establish a safety inspection diary, and seriously deal with potential safety accidents.

4. Carry out safety education and training for new workers, and only after passing the examination can they enter the operation post.

5, enter the construction site, must wear safety helmet, must wear a seat belt when engaged in aerial work, when pouring high altitude scaffolding set around the crossbar, and cloth safety net.

6, construction electricity set safety protection device, mechanical electrician often check the mechanical and electrical equipment, to ensure safety without accidents.

7. Strengthen safety and fire prevention education, and equip the site with "three treasures and one device" to prevent all accidents.

8, all kinds of mechanical equipment and transport vehicles to implement unified management and scheduling, it is forbidden to illegal operation, to ensure the safety of traffic operation.

9. Steel scaffolding should be provided with iron plate bearings, and the foundation should be flat and firm. The erection of steel pipe scaffold shall be horizontal, flat and firm, and bracing shall be provided. Crossbar joints shall be connected by fasteners, and scaffolding shall not be provided with probe plates.

10, construction at night must be equipped with lighting facilities, with special command and safety protection.

1 1. When adopting new technologies, new methods, new equipment or changing jobs, give workers safety education on new operation methods and new jobs.

Eight, summer (winter) rainy season construction technical measures

1, concrete construction in summer, shortening concrete transportation time, adding admixture with retarding effect in concrete to prevent concrete pump from blocking pipes.

2, high temperature season construction of concrete, assign personnel to sprinkler maintenance and cover wet straw bag.

3. For winter construction, purchase anti-freezing facilities and materials in advance to keep abreast of weather and temperature changes.

4. In winter concrete construction, Portland cement and ordinary Portland cement should be preferred, the water cement ratio should be strictly controlled, the concrete mixing time should be appropriately extended, the hot-mixed concrete should be used and the early-strength antifreeze should be added, the aggregate does not contain ice and snow, and the mold entry temperature should not be lower than 5℃, so as to shorten the concrete transportation time as much as possible, and thermal insulation measures should be taken for transporting concrete containers. After concrete and masonry are formed, they should be covered with thermal insulation immediately. 5, forming steel welding indoors, and take measures to prevent snow.

6, the rainy season construction to do a good job in the drainage of the construction site, ensure smooth drainage, strive to prevent before the rain, after the rain, pay attention to watch the weather forecast, cement and other materials susceptible to be affected with damp should be stored in high places, and do a good job of ventilation and waterproof, reinforced with ponchos to prevent corrosion. After the rain, before concrete pouring, the soil and sundries on the formwork and steel bars should be removed, and the foundation construction should prevent the rain from washing the foundation pit.

7, concrete pouring should try to avoid rainy days, as a last resort, strengthen the coverage.

Nine, the construction progress plan

In the whole construction process, we must grasp the key points, ensure the progress, mobilize all manpower and material resources to carry out the general campaign, fight hard, race against time, and strive to complete the construction task as planned.