Construction method of water supply and drainage well

Abstract

The application discloses a construction method of a water supply and drainage well, which adopts a method of top-down side excavation and side pouring and an inward staggered construction mode, effectively solves the problems of complicated process and slow construction progress in the prior art construction, guarantees safety, speeds up the progress, has small land occupation, does not need foundation pit supporting measures during construction, only needs to well do temporary protection, is convenient for ventilation system and ladder construction during top-down construction, adopts brick laying construction or steel structure installation for a well mouth reserved part, is convenient for chiseling and removing in the later period, is simple in construction, and is low in cost; the construction mode does not need to additionally construct a large construction operation platform, is constructed on an unexcavated soil surface, does not exist the risk of high-altitude operation, has small land occupation, is convenient for material transportation and hoisting and reinforced concrete construction, and greatly improves construction efficiency.

Description

Technical Field

[0001] This invention belongs to the field of municipal engineering technology, and specifically relates to a construction method for water supply and drainage wells. Background Technology

[0002] In municipal water supply and drainage engineering, various manholes for rainwater and sewage, intermediate manholes in pipeline projects, and pipe jacking manholes are frequently encountered, including large manholes with smaller manholes within them. In areas where conventional caisson methods cannot be used or construction is restricted, the advantages of cast-in-place methods become apparent. However, for deep, large-diameter rectangular or circular manholes, the method of excavating from top to bottom and then pouring concrete from bottom to top is relatively cumbersome and presents challenges in ensuring personnel safety and construction progress when working in confined spaces or within the foundation pit. Furthermore, the manhole opening of water supply and drainage manholes is usually cast as a whole, which makes subsequent excavation difficult. Therefore, it is necessary to design a construction method for water supply and drainage manholes to solve the above problems. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a construction method for water supply and drainage wells. This method adopts a top-down method of excavation and pouring, with each section staggered inward, which can ensure safety, speed up the progress, and occupy a small area. It also facilitates the construction of ventilation systems and the installation of ladders. The wellhead is constructed by brickwork or steel structure installation, which is convenient for chiseling and dismantling. The construction is simple and the cost is low, which solves the problems of complicated procedures and slow construction progress in the existing technology.

[0004] To achieve the above-mentioned technical effects, the technical solution adopted by the present invention is: a construction method for water supply and drainage wells, comprising the following steps: S1, Construction preparation and enclosure; S2, conduct surveying and setting out, and arrange observation points; S3, to carry out site clearing operations, level the site, and excavate and clean the site surface; S4, Piling rig positioning: The piling rig is kept horizontal, the pile tip is aligned with the pile position, and the drill rod is vertical; S5, carry out pile foundation construction around the excavation area; S6, Perform pile foundation maintenance: S601, the pile foundation shall be cured according to the predetermined time. S602, After the pile foundation is cured, core strength test is performed. If the pile foundation fails the test, the process of step S5 is repeated for reconstruction. S7. After the pile foundation construction is completed, the foundation pit is excavated and poured. The excavation and pouring are carried out from top to bottom, and the well opening is reserved. After the excavation boundary line of the foundation pit is determined and approved by the supervising engineer, the excavation process is carried out. The floating mud on the bottom of the foundation pit is cleaned and kept flat and dry. Drainage ditches are set up around the bottom and connected to the water collection well. Rainwater and groundwater collected in the water collection well are pumped out in time to prevent water accumulation from affecting the construction of the cutting edge cushion layer. S8, Concrete sealing construction at the bottom of the well; S9, the reserved portion of the wellhead shall be constructed by brickwork or installed with steel structure; S10, to carry out the lining construction of the inner wall of the drainage well and the installation of inspection wells inside the well, and to conduct functional testing of the pipeline and well; S11, Install the manhole cover, backfill the gap inside the manhole with soil, and chisel or dismantle the brickwork or steel structure reserved at the manhole opening. S12 will undergo construction and maintenance of the road surface at the wellhead, and will be opened to traffic.

[0005] Preferably, in step S7, the specific methods for the excavation and pouring of the foundation pit are as follows: S701, the foundation pit to be constructed is divided into sections from top to bottom according to a fixed depth; S702, excavation proceeds from top to bottom. After each section of the foundation pit is excavated, steel reinforcement is tied and formwork is installed. The steel reinforcement and formwork are staggered inward to form a stepped structure. S703, equipped with edge protection, ventilation system and ladder: Install a steel straight ladder passage, and install a guard ring on the ladder; the top of the ladder is firmly connected to the ground, and the ladder is connected to the well wall with expansion bolts; S704, pour and cure the concrete for this section of the foundation pit. After the concrete reaches 80% strength, remove the formwork and repeat steps S701 to S704 to excavate and pour the next section of the foundation pit. Continue excavating and constructing the foundation pit to the bottom of the well.

[0006] Furthermore, the reinforcing bars are centrally processed and transported to the site for unified installation and binding; the main reinforcing bars of the well body are all single-sided welded 10d, and the ring stirrups are bound, with a lap length of not less than 1.4La and not less than 300mm; the joint positions should be in places with less internal force, and should preferably be staggered, and the number of reinforcing bar joints in the same connection section should not exceed 50%; the length of the connection section of the reinforcing bar lap joint should not be less than 1.3 times the lap length; the protective layer thickness of the main reinforcing bars of the side wall and bottom plate is 40mm, and the protective layer thickness of the cover plate is 30mm.

[0007] Furthermore, after the reinforcement binding is inspected and accepted, the outer formwork and supports are erected; the formwork adopts a steel formwork splicing ring shape; the longitudinal spacing of the uprights is 1.4-1.5 meters, the transverse spacing of the uprights is 1.2 meters, and two layers of horizontal pipes are provided, with the ends of the steel pipes adjusted by top supports.

[0008] Preferably, in step S5, the pile foundation construction is high-pressure jet grouting pile construction, which specifically includes the following steps: S501, Pre-mixing and settling: When the soil is broken up, water should be flushed appropriately when the soil layer is hard or the settling is too slow. S502, Grout preparation: When the mixer descends to the top elevation of the pile, prepare the grout according to a water-cement ratio of 0.6. For the empty pile part, the grout can be replaced with water. S503, Grouting and Mixing: When the mixer descends to 500mm from the bottom of the pile, turn on the grout pump. After the pile driver drills to the designed bottom of the pile, spray grout while mixing and lifting. After lifting to the top of the pile, turn off the grout pump. Use the slow speed setting of about 1m / min. S504, Repeated Sinking: When the mixer is raised to the top elevation of the pile, the grout pump is turned off, and the pile is repeatedly sinked and mixed to make the grout and soil evenly mixed. The sinking speed is about 1.6m / min. S505, Repeated shotcrete lifting: When the pile sinks to the bottom elevation, turn on the grout pump to inject the remaining grout into the stratum, and stir while spraying grout, and lift to the designed top elevation of the pile, controlling the lifting speed to about 1m / min. S506, Flushing System: Flushing the grout pump and grout delivery system, and removing soft soil adhering to the drill bit; inspecting the drill bit and replacing worn drill bits; moving to a new pile location and repeating the above process.

[0009] Preferably, in step S8, the specific method for the concrete sealing construction at the bottom of the well is as follows: S801, after excavating to the design foundation elevation, lay a 20cm crushed stone cushion layer, use manual assistance to level the elevation, and excavate a drainage pit in the well for drainage according to the water volume; S802 After the foundation layer is completed, the bottom sealing reinforcement is tied and installed. The reinforcement installation is strictly carried out in accordance with the specifications. The bottom sealing concrete is poured immediately. A small slump is used when pouring the concrete. S803, when pouring underwater concrete for sealing the bottom, the guide pipes are set according to the effective radius of the guide pipes and the sealing area, with a spacing of 2.5 to 4m, and the deepest point is equipped with a guide pipe; when pouring concrete, the order is to pour from the lowest point to the highest point, and from the perimeter to the middle. S804. During the concrete pouring process, the tremie pipe is slowly raised vertically as the concrete surface rises. The depth of the tremie pipe embedded in the concrete is not less than 1m, and the average rising speed of the concrete surface is not less than 25cm per hour. The concrete pouring should be carried out as quickly as possible. When the concrete pouring of the tremie pipe is about to end, the slump of the concrete and the embedment depth of the tremie pipe should be increased. S805. When the bottom sealing concrete reaches the design strength and the working well can meet the anti-buoyancy requirements, pump water into the well and remove the loose concrete on the surface of the bottom sealing concrete. After cleaning, proceed with the construction of the bottom slab reinforced concrete.

[0010] The beneficial effects of this invention are as follows: 1. During construction, a top-down, simultaneous excavation and pouring method is adopted. After each section of the foundation pit is excavated, the steel reinforcement formwork is erected and the concrete is poured. Each section is staggered inward and constructed section by section from top to bottom. Compared with the existing construction method of excavating to the bottom at once and then pouring, this construction method excavates fewer foundation pits each time, does not require foundation pit support measures, and only requires edge protection. The construction area is small, which can ensure safety and speed up the progress. In addition, the top-down section-by-section pouring construction method also facilitates the construction and installation of ventilation systems and ladders. 2. The reserved wellhead portion is constructed using brickwork or steel structure installation. After the overall construction of the drainage well is completed, the reserved portion of the wellhead can be easily chiseled and dismantled, making the construction simple and cost-effective.

[0011] 3. No additional large construction platform is required. Construction is carried out on the unexcavated soil surface, and there is no work at height.

[0012] 4. It occupies a small area, which facilitates the transportation, hoisting, and reinforced concrete construction of materials. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the construction process of the present invention; Figure 2 This is an elevation view of the square structure drainage well of the variable-gradient inspection well in a specific embodiment of the present invention; Figure 3 This is a cross-sectional view of the square structure drainage well of the variable-gradient inspection well in a specific embodiment of the present invention; Figure 4 This is an elevation view of the square structure drainage well of the vertical inspection well in a specific embodiment of the present invention; Figure 5 This is a cross-sectional view of a square-shaped drainage well with vertical inspection wells in a specific embodiment of the present invention; Figure 6 This is an elevation view of a circular drainage well in a specific embodiment of the present invention; Figure 7 This is a cross-sectional view of a circular drainage well in a specific embodiment of the present invention. Detailed Implementation

[0014] Example 1: like Figure 1 A construction method for a water supply and drainage well includes the following steps: S1, Construction preparation and enclosure; S2, conduct surveying and setting out, and arrange observation points; S3, to carry out site clearing operations, level the site, and excavate and clean the site surface; S4, Piling rig positioning: The piling rig is kept horizontal, the pile tip is aligned with the pile position, and the drill rod is vertical; S5, carry out pile foundation construction around the excavation area; S6, Perform pile foundation maintenance: S601, the pile foundation shall be cured according to the predetermined time. S602, After the pile foundation is cured, core strength test is performed. If the pile foundation fails the test, the process of step S5 is repeated for reconstruction. S7. After the pile foundation construction is completed, the foundation pit is excavated and poured. The excavation and pouring are carried out from top to bottom, and the well opening is reserved. After the excavation boundary line of the foundation pit is determined and approved by the supervising engineer, the excavation process is carried out. The floating mud on the bottom of the foundation pit is cleaned and kept flat and dry. Drainage ditches are set up around the bottom and connected to the water collection well. Rainwater and groundwater collected in the water collection well are pumped out in time to prevent water accumulation from affecting the construction of the cutting edge cushion layer. S8, Concrete sealing construction at the bottom of the well; S9, the reserved portion of the wellhead shall be constructed by brickwork or installed with steel structure; S10, to carry out the lining construction of the inner wall of the drainage well and the installation of inspection wells inside the well, and to conduct functional testing of the pipeline and well; S11, Install the manhole cover, backfill the gap inside the manhole with soil, and chisel or dismantle the brickwork or steel structure reserved at the manhole opening. S12 will undergo construction and maintenance of the road surface at the wellhead, and will be opened to traffic.

[0015] Preferably, in step S7, the specific methods for the excavation and pouring of the foundation pit are as follows: S701, the foundation pit to be constructed is divided into sections from top to bottom according to a fixed depth; S702, excavation proceeds from top to bottom. After each section of the foundation pit is excavated, steel reinforcement is tied and formwork is installed. The steel reinforcement and formwork are staggered inward to form a stepped structure. S703, equipped with edge protection, ventilation system and ladder: Install a steel straight ladder passage, and install a guard ring on the ladder; the top of the ladder is firmly connected to the ground, and the ladder is connected to the well wall with expansion bolts; S704, pour and cure the concrete for this section of the foundation pit. After the concrete reaches 80% strength, remove the formwork and repeat steps S701 to S704 to excavate and pour the next section of the foundation pit. Continue excavating and constructing the foundation pit to the bottom of the well.

[0016] Furthermore, the reinforcing bars are centrally processed and transported to the site for unified installation and binding; the main reinforcing bars of the well body are all single-sided welded 10d, and the ring stirrups are bound, with a lap length of not less than 1.4La and not less than 300mm; the joint positions should be in places with less internal force, and should preferably be staggered, and the number of reinforcing bar joints in the same connection section should not exceed 50%; the length of the connection section of the reinforcing bar lap joint should not be less than 1.3 times the lap length; the protective layer thickness of the main reinforcing bars of the side wall and bottom plate is 40mm, and the protective layer thickness of the cover plate is 30mm.

[0017] Furthermore, after the reinforcement binding is inspected and accepted, the outer formwork and supports are erected; the formwork adopts a steel formwork splicing ring shape; the longitudinal spacing of the uprights is 1.4-1.5 meters, the transverse spacing of the uprights is 1.2 meters, and two layers of horizontal pipes are provided, with the ends of the steel pipes adjusted by top supports.

[0018] Preferably, in step S5, the pile foundation construction is high-pressure jet grouting pile construction, which specifically includes the following steps: S501, Pre-mixing and settling: When the soil is broken up, water should be flushed appropriately when the soil layer is hard or the settling is too slow. S502, Grout preparation: When the mixer descends to the top elevation of the pile, prepare the grout according to a water-cement ratio of 0.6. For the empty pile part, the grout can be replaced with water. S503, Grouting and Mixing: When the mixer descends to 500mm from the bottom of the pile, turn on the grout pump. After the pile driver drills to the designed bottom of the pile, spray grout while mixing and lifting. After lifting to the top of the pile, turn off the grout pump. Use the slow speed setting of about 1m / min. S504, Repeated Sinking: When the mixer is raised to the top elevation of the pile, the grout pump is turned off, and the pile is repeatedly sinked and mixed to make the grout and soil evenly mixed. The sinking speed is about 1.6m / min. S505, Repeated shotcrete lifting: When the pile sinks to the bottom elevation, turn on the grout pump to inject the remaining grout into the stratum, and stir while spraying grout, and lift to the designed top elevation of the pile, controlling the lifting speed to about 1m / min. S506, Flushing System: Flushing the grout pump and grout delivery system, and removing soft soil adhering to the drill bit; inspecting the drill bit and replacing worn drill bits; moving to a new pile location and repeating the above process.

[0019] Preferably, in step S8, the specific method for the concrete sealing construction at the bottom of the well is as follows: S801, after excavating to the design foundation elevation, lay a 20cm crushed stone cushion layer, use manual assistance to level the elevation, and excavate a drainage pit in the well for drainage according to the water volume; S802 After the foundation layer is completed, the bottom sealing reinforcement is tied and installed. The reinforcement installation is strictly carried out in accordance with the specifications. The bottom sealing concrete is poured immediately. A small slump is used when pouring the concrete. S803, when pouring underwater concrete for sealing the bottom, the guide pipes are set according to the effective radius of the guide pipes and the sealing area, with a spacing of 2.5 to 4m, and the deepest point is equipped with a guide pipe; when pouring concrete, the order is to pour from the lowest point to the highest point, and from the perimeter to the middle. S804. During the concrete pouring process, the tremie pipe is slowly raised vertically as the concrete surface rises. The depth of the tremie pipe embedded in the concrete is not less than 1m, and the average rising speed of the concrete surface is not less than 25cm per hour. The concrete pouring should be carried out as quickly as possible. When the concrete pouring of the tremie pipe is about to end, the slump of the concrete and the embedment depth of the tremie pipe should be increased. S805. When the bottom sealing concrete reaches the design strength and the working well can meet the anti-buoyancy requirements, pump water into the well and remove the loose concrete on the surface of the bottom sealing concrete. After cleaning, proceed with the construction of the bottom slab reinforced concrete.

[0020] Example 2: In step S7, the concrete pouring process is as follows: (1) The designed concrete grade is C30. After the formwork and support work is completed, it must be inspected and accepted by the supervising engineer. Only after the inspection and acceptance can the concrete be poured. In order to shorten the construction period and ensure the quality of the project, pumped ready-mixed concrete is used. When the height of the working surface inside the well does not exceed 2 meters, the concrete is transported to the wellhead by hand truck or excavator for pouring. When the depth of the working surface inside the well exceeds 2 meters, the concrete is pumped to the construction position by pressure pump.

[0021] (2) The free height of the concrete pouring should not exceed 2m. The concrete pouring should be carried out symmetrically and evenly, using the layered flat laying method, with the layer thickness controlled at about 30cm. During vibration, prevent missed vibration, under-vibration and over-vibration to ensure the quality of the concrete.

[0022] (3) During the pouring process, strengthen the observation of the elevation difference and subsidence of the working well. As the total amount of concrete poured increases, the measurement density should be increased accordingly. If any unexpected situation occurs, take corresponding measures to ensure the construction safety of the working well.

[0023] (4) Make full preparations before each concrete pouring, and conduct slump resistance and compressive strength tests according to specifications for each concrete pouring. Reinforcing bars, formwork and various embedded parts shall pass the concealed acceptance inspection.

[0024] (5) Before concrete pouring, the formwork and support process must be completed and the concrete must be inspected by the supervising engineer. The preparation work must be fully checked and the technical instructions must be given. The division of labor and zoning of each team must be clarified. Before the concrete is put into the formwork, all kinds of garbage in the formwork must be removed and the formwork must be moistened with water. The concrete can only be poured after the formwork is inspected and approved.

[0025] (6) During construction, strictly control the initial setting time difference and surface concrete quality, pay special attention to concrete slump, flow and segregation, and prevent cold joints. When vibrating concrete, the vibrator should be inserted into the lower layer of concrete about 10cm. Pay attention to avoid under-vibration and over-vibration. Strengthen vibration in areas with dense reinforcement. Extend vibration to about 1.5m at the junction of zones to ensure that the concrete is smooth on the outside and solid on the inside. Reinforcing steel workers and carpenters should strengthen their on-duty inspections and deal with problems in a timely manner to ensure normal construction. They can only leave their posts after the situation is cleared during shift handover.

[0026] (7) Concrete vibration shall be carried out using an immersion vibrator. When inserting the vibrator, it should be away from the reinforcing bars, but care should be taken to prevent uneven vibration and excessive compaction of the concrete, which may lead to segregation. During concrete vibration, attention should be paid to and the stress on the formwork and reinforcing bars should be checked at any time to prevent the formwork from running away due to concrete vibration. During the concrete pouring process, concrete test blocks should also be prepared to ensure the completeness of quality assurance data.

[0027] The above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The embodiments and features described in these embodiments can be arbitrarily combined without conflict. The scope of protection of the present invention should be limited to the technical solutions described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

Claims

1. A construction method for a water supply and drainage well, characterized in that: Includes the following steps: S1, Construction preparation and enclosure; S2, conduct surveying and setting out, and arrange observation points; S3, to carry out site clearing operations, level the site, and excavate and clean the site surface; S4, Piling rig positioning: The piling rig is kept horizontal, the pile tip is aligned with the pile position, and the drill rod is vertical; S5, carry out pile foundation construction around the excavation area; S6, Perform pile foundation maintenance: S601, the pile foundation shall be cured according to the predetermined time. S602, After the pile foundation is cured, core strength test is performed. If the pile foundation fails the test, the process of step S5 is repeated for reconstruction. S7. After the pile foundation construction is completed, the foundation pit excavation and pouring operations are carried out, excavating and pouring from top to bottom, and reserving well openings; the specific methods for foundation pit excavation and pouring operations are as follows: S701, the foundation pit to be constructed is divided into sections from top to bottom according to a fixed depth; S702, excavation proceeds from top to bottom. After each section of the foundation pit is excavated, steel reinforcement is tied and formwork is installed. The steel reinforcement and formwork are staggered inward to form a stepped structure. S703, equipped with edge protection, ventilation system and ladder: Install a steel straight ladder passage, and install a guard ring on the ladder; the top of the ladder is firmly connected to the ground, and the ladder is connected to the well wall with expansion bolts; S704, pour and cure the concrete for this section of the foundation pit. After the concrete reaches 80% strength, remove the formwork and repeat steps S701~S704 to excavate and pour the next section of the foundation pit. Excavate and construct to the bottom of the well in sequence. S8, Concrete sealing construction at the bottom of the well; S9, the reserved portion of the wellhead shall be constructed by brickwork or installed with steel structure; S10, to carry out the lining construction of the inner wall of the drainage well and the installation of inspection wells inside the well, and to conduct functional testing of the pipeline and well; S11, Install the manhole cover, backfill the gap inside the manhole with soil, and chisel or dismantle the brickwork or steel structure reserved at the manhole opening. S12, construction and maintenance of the road surface at the wellhead will be carried out, and traffic will be opened; The construction of the concrete sealing at the bottom of the well includes excavating to the designed base elevation, laying a 20cm crushed stone cushion layer, manually leveling the elevation, and excavating a drainage pit inside the well for drainage purposes, depending on the water volume. After the cushion layer is completed, the sealing reinforcement is tied and installed, strictly following the specifications. The sealing concrete is then poured immediately. A small slump is used when pouring the concrete. When pouring the underwater sealing concrete, tremie pipes are installed according to the radius of action of the tremie pipes and the sealing area, with a spacing of 2.5~4m, and a tremie pipe is placed at the deepest point. Concrete is poured from the lowest point first, followed by the next. For higher areas, proceed from the perimeter to the center. During concrete pouring, the tremie pipe should be raised vertically as the concrete surface rises, with the tremie pipe embedded in the concrete to a depth of not less than 1m and the average rising speed of the concrete surface not less than 25cm per hour. Concrete pouring should be carried out as quickly as possible. When the concrete pouring of the tremie pipe is nearing completion, the slump of the concrete and the embedment depth of the tremie pipe should be increased. When the bottom sealing concrete reaches the design strength and the working well meets the anti-buoyancy requirements, water should be pumped out of the well, and the loose concrete on the surface of the bottom sealing concrete should be removed. After cleaning, the reinforced concrete construction of the bottom slab should be carried out.

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