constitute:

The plastic inspection well is composed of a well seat, a well shaft, a well cover and plastic inspection well parts. The inspection well shaft can be made of buried drainage pipes, such as PVC-U double-layer axial hollow pipes, HDPE hollow winding pipes, etc.

According to the number of pipes and angles, there are starting well seats, straight well seats, three-way well seats, four-way well seats, 90-degree elbow well seats, etc. In order to adapt to various drainage conditions, plastic inspection wells are also equipped with matching plastic inspection well parts such as inner and outer diameter conversion joints, saddle joints, reducers, confluence joints, and angle-changing joints. These parts and well seats are used together to ensure the fluidity and sealing of the entire drainage system.

Manhole covers can be cast iron, composite, or steel fiber concrete. The quality meets the requirements of the current "Plastic Manholes for Drainage in Building Residential Areas" CJ/T233-2006. The color is white or gray, and the inner and outer walls of the shaft should be smooth and flat. There should be no bubbles, cracks, depressions, uneven color, or decomposition discoloration lines on the surface. The plastic shaft seat has no cracks or fissures under a static load pressure of 15KN.

Plastic inspection well application range

(1) Design, construction and maintenance of plastic drainage inspection well projects with an outer diameter of no more than 1200mm and a buried depth of no more than 8m in building communities (residential areas, public building areas, factory areas, etc.), urban and rural municipalities, industrial parks, and old city reconstruction.

(2) Construction of plastic drainage inspection wells under general soil conditions, soft soil conditions, seasonal frozen soil conditions and collapsible loess soil conditions.

(3) Areas with a seismic fortification intensity of 9 degrees or less.

(4) The ground load of a general lane is designed based on the gross vehicle weight of 15 t (5 t under rear wheel pressure); the ground load of a fire lane is designed based on the gross vehicle weight of 30 t (6 t under rear wheel pressure).

(5) The groundwater level is designed to be no higher than 1.0m below the ground.

Well diameter series: Well diameter and drainage pipe diameter soil matching table Unit: mm

Note: Wellbore diameter (mm) (DN) = inspection well diameter

Component selection:

The connection between the well seat and the buried pipeline should use a flexible connection with a rubber sealing ring to adapt to the deformation of the ground seat, etc. Adhesives can only be used for socket-type connections between PVC-U well seats and wellbore diameters of 315mm or less.

Plastic inspection well parts selection:

(1) Inspection well seats with flow grooves should be used on sewage pipes;

(2) The manhole seat of the inspection well on the rainwater pipe shall meet the following requirements:

a. The road rainwater outlet should adopt a well seat with a mud chamber;

b. When a check well for a sludge chamber well seat is required on a rainwater pipe, it should be installed outside the wellbore.

Inspection wells with a diameter greater than or equal to 500mm;

c. Other rainwater inspection wells can use well seats with flow grooves;

Functional advantages:

The functional advantages of plastic inspection wells mainly include five aspects: land saving, energy saving, water saving, material saving and environmental protection.

(1) Acid and alkali corrosion resistance, aging resistance, and long service life.

(2) Safety and environmental protection. The material of the plastic inspection well is high-density polyethylene plastic, which is non-toxic and odorless and can be recycled after use. It is a chemical environmentally friendly building material and complies with the national environmental protection policy.

(3) Uniform settlement and pressure resistance. The pipe is flexibly connected to the well seat, and the clay of the pipe and the well seat move together, which effectively solves the problem of uneven settlement caused by the connection between traditional inspection wells and plastic pipes, and effectively prevents ground collapse.

(4) Convenient and quick construction. The split assembly structure is adopted, and the shaft can be cut and adjusted on site to meet various installation depth requirements, effectively reducing costs, greatly improving construction progress, and shortening the construction period by more than 10-20 times that of traditional inspection wells; and it can be constructed around the clock, which is incomparable to brick inspection wells and other cement brick wells.

(5) Efficient drainage. The inner wall is smooth and has a diversion groove, which makes it difficult for dirt to be retained, reducing the possibility of blockage. It has excellent drainage performance, and the rainwater and sewage discharge rate is 1 to 3 times that of traditional inspection wells.

(6) Light weight, easy to transport and install, reliable performance, strong carrying capacity; strong adaptability and complete varieties, the shaft height can be adjusted arbitrarily, holes can be drilled on the shaft, and the direction can be adjusted to meet all the needs of engineering installation.

(7) The overall cost is low and the maintenance cost is low, which is more advantageous than traditional inspection wells; it can be recycled and reused, which has huge social benefits.

(8) Good sealing performance and anti-leakage. The flexible connection method is flexible and convenient, and can overcome the harsh construction environment of wind, dust, sand and ash. The good sealing performance can prevent the leakage of rainwater and sewage to prevent groundwater pollution. It can also overcome the difficulty of repeated insertion due to the increase in road surface.

(9) Save materials. Plastic inspection wells are made of polymer resin instead of red brick cement, saving topsoil resources; the specifications used in building communities are reduced, which greatly saves the land space occupied by buried inspection wells.

National policy:

1. Policy advantages

It conforms to the national conditions of sustainable development and is a new type of high-quality environmentally friendly product supported by national policies.

The relevant national policy documents are as follows

1. Document No. 218 of the Ministry of Construction in 2004

2. On June 14, 2007, the Ministry of Construction of the People's Republic of China issued Announcement No. 659, "Technologies for Promotion and Restriction of Use in the Construction Industry during the 11th Five-Year Plan Period (First Batch)"

3. Documents from provincial and regional construction departments prohibiting the use of traditional brick wells;

3.1. Documents from Beijing Municipal Commission of Housing and Urban-Rural Development;

3.2. Documents from Shanghai Municipal Commission of Urban and Rural Construction and Transportation;

3.3. Documents from the Jiangsu Provincial Department of Housing and Urban-Rural Development;

3.4. Documents from Sichuan Provincial Construction Department;

3.5. Documents from the Shanxi Provincial Department of Construction;

3.6. Documents from Chongqing Municipal Construction Committee;

3.7. Documents from the Yunnan Provincial Department of Housing and Urban-Rural Development;

3.8. Beijing Plastic Inspection Well Construction Project Atlas

4. The Ministry of Construction of the People's Republic of China issued Document No. 218 in 2004, which clearly prohibits the use of solid clay bricks and promotes the use of plastic inspection wells.

5. The National Ministry of Construction's "Eleventh Five-Year Plan" technical bulletin states that plastic pipes should be used first and plastic inspection wells should be used instead of brick wells. It requires local construction departments and design departments to pay attention to the use of plastic inspection wells when designing construction plans.

6. The Sichuan Provincial Department of Construction issued Document No. 297 of 2006: "Notice on the Prohibition of the Use of Brick Manholes in Municipal and Residential Construction Projects". Construction projects that illegally use brick-built inspection manholes will be deemed to have used unqualified building materials and building components, and the responsible units and persons in charge will be punished in accordance with relevant laws and regulations.

7. Chongqing Municipal Construction Committee Document No. Yu Jian Fa (2009) 68, Notice of Chongqing Municipal Construction Committee on the Issuance of "Notice on the Prohibition of the Use of Behind-the-Building Technology in the Construction Field of Chongqing" (No. 5).

Standard basis:

Foreign standards

1. European standard PREN193598.2:2004 "Specifications for manholes and inspection wells in traffic areas and deep buried installations";

2. British Standard BS7158:2001 "Plastic inspection wells for drainage and sewage";

3. Japanese standard JISA5731:2002 "Recycled plastic inspection wells and manhole covers for rainwater", Japan Sewerage Association standard JSWASK-7 "Hard polyethylene inspection wells for sewers" and JSWASK-9 "Hard polyethylene small inspection wells for sewers".

Domestic Standards

1. National Building Standard Design Atlas 08SS523 "Plastic Drainage Inspection Wells in Building Residential Areas";

2. CJ/T233-2006 "Plastic inspection wells for drainage in building communities", the urban construction industry standard of the People's Republic of China;

3. Engineering Construction Standardization Association Standard CECS227:2007 "Technical Specifications for Application of Plastic Drainage and Plastic Inspection Wells in Building Residential Areas";

4. CJ/T326-2010 "Plastic inspection wells for municipal drainage".

Well pit and foundation

1. The pit should be excavated at the same time as the trench. During excavation, the main pipeline of the pit seat should be on the same axis as the pipeline in the trench. The slope of the pit should be consistent with the slope of the trench. When excavating the pit, the base soil should not be disturbed or over-excavated; if the base soil is disturbed, it should be in accordance with the current "Construction and Acceptance Specifications for Water Supply and Drainage Pipeline Engineering" GB

50268, and take remedial measures according to the soil quality of the base soil. For rainwater inspection wells with sludge chambers, the depth of the sludge chamber should be partially excavated according to the selected specifications. The excavation of the well pit should be based on the selected specifications, taking into account the offset factor of the main line of the well seat, and the pit wall at the offset end should be flush with the pipe trench.

2. In areas with high groundwater levels or during construction in the rainy season, drainage and lowering measures should be taken.

3. The inspection well foundation should be determined by calculation based on the local geological survey data and the backfill soil drag force. If there is no data, the inspection well foundation drawing can be used for construction.

Installation of inspection well pipe

1. Check the installation sequence of the well seat and pipeline connection. Start from the upstream section of the household pipe, install in the sequence of well-pipe-well-pipe, and gradually extend to the downstream branch pipe and main pipe.

2. The construction method of connecting the well seat joint to the pipeline should be consistent with the construction method of connecting the pipeline with the same type of joint.

3. The connection between the well seat and the inlet and outlet pipes requires a diameter change. When using a reducing joint, when the inlet pipe diameter is smaller than the well seat interface pipe diameter, the top of the pipe should be connected flatly; when the well seat outlet pipe interface is larger than the downstream pipeline, the inner bottom of the pipe should be connected flatly.

4. When the pipeline uses a variable angle joint or a ball joint to adjust the slope, when the pipe diameter is 315mm, special tools should be used and chain wrenches should not be used.

5. The installation of additional joints should be based on the wellbore size and the diameter of the connecting pipe. Use special tools to drill holes in the well wall. The circumferential edge of the hole should be flat, and the additional joints should not be installed on a reverse slope.

6. During construction periods when the groundwater level is high or in the rainy season, when the pipeline (including the inspection well) is installed (but the water filling test has not yet been carried out), technical measures should be taken to prevent the well body from floating.

Wellbore installation

1. The length of the shaft should be the height from the bottom of the socket of the shaft seat to the designed ground, minus the net distance from the top of the shaft to the ground. When the ground or road elevation is difficult to determine accurately, the shaft length can be appropriately reserved.

2. The wellbore should be kept vertical when inserted into the well seat. When plugging the wellbore, do not use a heavy hammer to hit it, and use a special tightening tool.

Backfill

1. Backfilling should be carried out after the drainage pipeline (including pipes and inspection wells) has been accepted and should be carried out simultaneously with the backfilling of the pipeline trench.

2. Before backfilling, sand bags, steel chisels and wooden supports can be used to fix the well seat and well shaft, and the accumulated water in the foundation pit and trench should be removed.

3. Backfill materials: The backfill materials for the trench within the range of 0.5m from the bottom foundation of the pipe to the top of the pipe can be crushed stone, sand with a particle size less than 40mm, high (medium) calcium fly ash, medium-coarse sand or good quality soil excavated from the trench.

4. Backfill soil must not be silt, garbage, frozen soil, etc., and must not contain stones, bricks, or other hard objects with sharp edges.

5. When the local maximum frozen soil depth is greater than or equal to 1.0m, medium-coarse sand should be backfilled within a range of no less than 100m around the wellbore within the frozen layer.

6. Backfilling should be done manually in layers and symmetrically. The density should be consistent with the pipeline backfilling, and the wellbore should not be displaced or tilted. Mechanical backfilling is strictly prohibited.

Manhole cover installation

1. Before installing the manhole cover, the length of the wellbore should be accurately measured and the excess part of the wellbore should be cut off.

2. The installation of manhole covers should be determined according to the properties of the conveying medium of the inspection well, and sewage manhole covers and rainwater manhole covers should not be confused.

3. An inner cover should also be installed at the top of the wellbore of the sewage inspection well with a protective cover.

4. Use C20 fine stone concrete for on-site pouring; if prefabricated reinforced concrete is required, it must be designed separately by the structural professional.

Water-tightness test

The water-tightness test should be carried out in accordance with the current technical regulations for buried plastic drainage pipe engineering.

Backfill details:

1. For backfill soil, generally no stones or other hard objects with edges and corners should be mixed in;

2. Backfilling should be carried out in layers and symmetrically, and the wellbore should not be displaced or tilted;

3. When backfilling in layers, it should be noted that the thickness of each layer of backfill soil should not be greater than 300mm.

4. Backfilling should be done manually, not mechanically;

5. Each layer of backfill should be compacted symmetrically using light compaction tools such as wooden tampers, and its density should be consistent with the pipeline backfill;

6. Backfilling should be carried out after the drainage pipeline is accepted; Biaolong laser marking machine

7. Before backfilling, water in the foundation pit and trench should be removed;

8. When the plastic inspection well on the road is backfilled to the upper part of the well shaft, the size of the well cover foundation pit should be reserved around the well shaft according to the backfill soil quality and the characteristic value of the backfill foundation bearing capacity;

9. The backfilling of the plastic inspection well should be carried out at the same time as the backfilling of the pipeline trench;

10. Silt, garbage and frozen soil shall not be used as backfill soil;

11. Before backfilling, sand bags, steel chisels and wooden supports can be used to fix the well base and wellbore.

Production process:

1. Plastic inspection wells produced by injection molding are formed in one step, with high production efficiency and good quality. The disadvantage is that the mold price is relatively high. At the same time, it is limited by the processing performance of the raw materials and the power of the injection molding machine. It is suitable for the production of plastic inspection wells with a diameter of less than 800mm.

2. The advantages of plastic inspection wells produced by winding and secondary molding processes are that they can be made from local materials, are quick to start up, and can produce inspection wells of different specifications. The disadvantages are slow speed, low efficiency, and the quality (especially welding quality) is easily affected by human factors and fluctuates.

3. The advantage of the secondary molding inspection well using the layer coating process is that it can be quickly put into operation using local materials, and different specifications of plastic inspection wells can be produced. The disadvantage is that the speed is slow and it is difficult to mass produce. In addition, the product size and performance are difficult to guarantee due to the pure manual production. Environmental pollution during production and the inability to recycle raw materials limit its production and use.

4. The plastic inspection well produced by rotational molding has high hardness.

Plastic inspection wells will completely replace traditional brick wells with their superior performance.

Design of well base structure

When the plastic inspection well is buried underground, the vertical dynamic load acting on the well cover, the weight of the well body, and the drag force under the soil acting on the well shaft constitute the vertical load of the inspection well. All vertical loads are ultimately transferred to the well seat, which is the core part of the plastic inspection well components.

Vertical force analysis

Because the model is too large and the main surface of the model is an irregular curved surface, and the reinforcement ribs in the vertical, horizontal and oblique directions are interlaced, making the analysis impossible, the model is simplified. Without considering the oblique reinforcement, when doing vertical force analysis, the horizontal reinforcement is simplified; when doing horizontal force analysis, the vertical reinforcement is simplified. Such an analysis result will make the strain slightly greater than the actual situation, while the stress is basically the same. Calculation data: The weight of a single wheel of the car is 80KN (8 tons). The maximum calculated stress is 18MPa.

Maintenance method:

For the maintenance of plastic inspection wells, we should start from the following aspects:

1. It is advisable to use special dredging machinery to implement hydraulic maintenance for pipeline clearing. The maintenance tools we usually use include common tools such as shovels, lead buckets, mud bags, etc.; sometimes some professional tools are also needed, such as sludge pliers, high-pressure water guns, etc.

2. When there is mud and sand in the rainwater inspection well, we should use mechanical mud suction tools to clean it. If manual cleaning is used, special cleaning tools should be used.

3. When checking for mud accumulation in the pipeline, you must not go down into the well to detect, and should use an inspection mirror for visual inspection.

4. When implementing maintenance and servicing, conspicuous warning signs should be placed around the inspection well.

5. After maintenance, the manhole cover should be promptly covered as it was, and the inner cover of the sewage pipe inspection well should also be covered.

6. When the manhole cover is damaged or lost due to external reasons, the maintenance department should replace it in time according to the original type and specifications.