AU2021105980A4 - Construction method for impervious concrete for mbbr water treatment process structure - Google Patents

Abstract

The present invention relates to the technical field of concrete construction, in particular to a construction method for impervious concrete for an MBBR water treatment process structure. By reasonably setting the quantity and position of embedded parts, the present invention may reduce the construction cost and ensure the construction quality at the same time; tapered heads and extension tie bars at both ends of an embedded tie bar may be disassembled and reused, thus further reducing the construction cost; and construction molding by continuous placing may not only meet the requirements of anti-seepage but also realize the tightening of construction formwork after concrete curing and formwork removal according to the set conditions, so as to ensure the construction to meet the requirements for surface degree and ensure the overall concrete quality after construction. SOlI: fabricating and installing reinforcements and installing inner and outer mounting frames outside the reinforcements Fig. S02:~ 3arctn osrcinfrwr n etn otmcntuto formork nd suportfrmoncioncnre.2ntaln tewl

Description

SOlI: fabricating and installing reinforcements and installing inner and outer mounting frames outside the reinforcements

Fig.

S02:~ osrcinfrwr n etn 3arctn otmcntuto

formork nd suportfrmoncioncnre.2ntaln tewl

CONSTRUCTION METHOD FOR IMPERVIOUS CONCRETE FOR MBBR WATER TREATMENT PROCESS STRUCTURE

Technical Field The present invention relates to the technical field of concrete construction, in particular to a construction method for impervious concrete for an MBBR water treatment process structure.

Background

Environmental pollution and treatment are the key issues nowadays, especially for wastewater treatment, which directly affects people's life and work. For wastewater treatment, there are traditional fixed-bed reactor wastewater treatment method, fluidized bed reactor wastewater treatment method, submerged biofilter wastewater treatment method and so on, as well as MBBR (Moving-Bed Biofilm Reactor, MBBR) water treatment process proposed in recent years, in which MBBR may run continuously, without blockage, without backwashing, with small head loss and large specific surface area, and the corresponding water treatment process has high organic matter removal efficiency and strong phosphorus and nitrogen removal ability, which has been generally recognized in the industry.

However, MBBR water treatment process has more complex structural requirements for water treatment structures, higher requirements for anti-seepage and anti-crack, comprehensive anti-corrosion, precision and strength, and its construction is more difficult. In the actual construction, the construction quality is often not up to standard, which not only reduces the construction efficiency, but also reduces the effect of MBBR wastewater treatment.

Therefore, it is necessary to put forward a more reasonable technical solution to solve the technical problems existing in the prior art.

Summary

In order to overcome defects of the prior art mentioned above, the present invention provides a construction method for impervious concrete for an MBBR water treatment process structure, aiming at controlling the surface flatness and verticality of the structural plane by accurately controlling the size of the structural plane, so as to ensure the construction quality. In addition, the quantity of tie bars is optimized in the construction process to achieve the purpose of economy and safety. At the same time, the construction method may effectively control the water seepage of structures and avoid the leakage of tank body in the later period.

To achieve the foregoing object, the technical solution of the present invention is as follows:

a construction method for impervious concrete for an MBBR water treatment process structure, comprising:

fabricating and installing reinforcements and installing inner and outer mounting frames outside the reinforcements;

fabricating a construction formwork and setting a bottom construction formwork and a support frame on cushion concrete; installing a wall construction formwork on the mounting frame by hoisting;

arranging a plurality of embedded parts on reinforcements and tightening the wall construction formwork through the embedded parts; and

for concrete placing, adopting one-time continuous placing, wetting and curing concrete after condensation, and curing for at least the specified period of time; after curing, stripping, and controlling the temperature difference between the temperature of concrete surface layer and the ambient temperature to be within the specified range during stripping.

In the construction method disclosed above, the construction formwork is connected and fastened by reasonably setting embedded parts, the construction formwork is formed by continuous placing, and the concrete curing and formwork removal are carried out according to the set conditions, which may tighten the construction formwork, meet the anti-seepage requirements after construction, ensure the construction to meet the requirements for surface degree, and ensure the overall concrete quality after construction.

In the technical solution, before wall construction of the structure, foundation treatment such as leveling and strengthening of foundation are carried out, cushion concrete is poured as a floor, and the structure is constructed on the basis of cushion concrete. Specifically, the construction formwork is set before the construction of the structure, and the following feasible solutions are adopted. The setting of a bottom construction formwork on the cushion concrete comprises the following steps:

further, putting the baseline on the cushion concrete to determine an installation position of the bottom construction formwork, connecting and fixing the bottom construction formwork through the support frame, and testing and adjusting the bottom construction formwork to the design verticality.

It may be seen that the underwater pressure is directly proportional to the depth of water, and the water pressure at the bottom of cushion concrete and structure is the largest. When the structure is a high tank wall structure, the bottom joint between cushion concrete and structure is prone to water seepage. Therefore, adopting the above method to set the benchmark on the bottom concrete and setting the bottom construction formwork strictly according to the baseline may improve the rigor of subsequent concrete placing construction, and there are no construction joints and other structures between the completed structures and the bottom concrete, with good integration and higher anti-seepage performance.

Still further, in the construction formwork setting mode disclosed in the technical solution, because there are several construction formworks, which are arranged in a continuous laying mode when laying, it is necessary to make the stability and flatness of adjacent construction formworks correspond to each other. A concrete and feasible solution is given here: a plurality of layers of construction formworks are arranged from bottom to top, each layer of construction formwork is provided with an independent support frame, the support frame of the upper layer of construction formwork is erected on the support frame of the lower layer of construction formwork, and the adjacent two layers of construction formworks are strengthened by reinforcing parts. The function of reinforcing parts is to fix the upper and lower layers of support frames so that the relative stability of the upper and lower layers of construction formworks is stronger and the surface consistency of concrete after construction molding is better.

Further, in order to avoid slurry leakage in the construction process, the setting mode of construction formwork is optimized, and the following specific feasible scheme is given here as an example: when installing construction formwork, a seal strip is provided at the joint between adjacent construction formworks. The seal strip is made of flexible material, which may fully fill the transverse joint and the longitudinal joint between construction formworks to achieve the sealing effect.

Further, the embedded parts disclosed in the technical solution are used for connecting and fastening construction formworks, the embedded parts comprise an embedded tie bar, both ends of the embedded tie bar are provided with a thread and are connected with a tapered head, both ends of the embedded tie bar are also connected with an extension tie bar through the tapered head, the embedded tie bar is buried in a wall with concrete placing, and the extension tie bar is used for tightening the construction formwork and the support frame. In specific application, the tapered head is provided with connecting through holes, the length of the tapered head after being arranged at both ends of the embedded tie bar is just equal to the thickness of the wall, the narrow end of the tapered head faces the concrete wall, the wide end of the tapered head faces the construction formwork, the construction formwork is provided with corresponding connecting holes, and the connecting holes are matched and fastened with the extension tie bar.

Further, the embedded parts are arranged inside the poured concrete wall and penetrate through the concrete wall. In order to ensure the effect of preventing water seepage, the structure of the embedded tie bar is optimized. Specifically, the following feasible solution is given as an example: the embedded tie bar is provided with a waterstop, and the waterstop is sleeved on the embedded tie bar and is at least 2 cm higher than the surface of the embedded tie bar. When a waterstop is arranged, the hole where the embedded tie bar is located is sealed by the waterstop, and the joint between the waterstop and the embedded tie bar has a fully welded sealing structure, thus preventing water from penetrating from one side of the wall to the other side through the embedded tie bar hole.

Further, as the walls under construction are generally high walls after the construction formwork is set up, impurities may enter the placing space and affect the construction quality, so it is necessary to clean the placing space in advance, and the following optimized and specific feasible scheme is given as an example: at the root of the wall construction formwork, a cleanout is set at every specified distance.

Further, in order to ensure the smooth and clean construction surface in the later period and avoid damaging the surface degree of concrete construction during stripping, the following feasible technical solution is given as an example: the construction formwork is coated with a stripping agent, which is brushed before concrete placing, so that it is easier to remove the construction formwork in the later period and protect the concrete surface after stripping from damage.

Further, strictly controlling the process of concrete placing and vibrating is the key to improve the quality of concrete placing. The optimization restriction is carried out here and the following specific feasible technical solution is as an example: in the process of concrete placing, the height of formed concrete is less than or equal to 0.5 m per hour.

Still further, the raw materials for concrete used are limited to achieve better construction effect, and the following optimized and specific feasible scheme is given as an example: using slag cement greater than or equal to P42.5 for preparing concrete.

Compared with the prior art, the present invention has the following beneficial effects:

by reasonably setting the quantity and position of embedded parts, the present invention may reduce the construction cost and ensure the construction quality at the same time; tapered heads and extension tie bars at both ends of an embedded tie bar may be disassembled and reused, thus further reducing the construction cost; and construction molding by continuous placing may not only meet the requirements of anti-seepage but also realize the tightening of construction formwork after concrete curing and formwork removal according to the set conditions, so as to ensure the construction to meet the requirements for surface degree and ensure the overall concrete quality after construction.

Brief Description of the Drawings In order to illustrate the technical solutions of the embodiments of the present invention more clearly, the accompanying drawings used in the embodiments will be introduced below briefly. It should be understood that the accompanying drawings described below show some embodiments of the present invention only, and should not be construed as restriction to the scope. Those of ordinary skill in the art may also obtain other accompanying drawings based on those accompanying drawings without creative work.

Fig. 1 is a process schematic diagram of the construction method.

Fig. 2 is a structural schematic diagram of embedded parts adopted in the embodiments.

The meanings of labels in the above figure are: 1. embedded tie bar; 2. extension tie bar; 3. waterstop; and 4. tapered head.

Description of the Preferred Embodiments

The present invention will be further described below in conjunction with accompanying drawings and preferred embodiments.

It should be noted here that the description of the embodiments is intended to help understand the present invention, but does not constitute a limitation to the present invention. The specific structural and functional details disclosed herein are only intended to describe exemplary embodiments of the present invention. However, the present invention may be embodied in many alternative forms and should not be construed as being limited to the embodiments set forth herein.

Embodiment As the existing water treatment structures are prone to water seepage after construction, the embodiment improves the construction method to improve the anti-seepage performance of the structures; and at the same time, the improved construction method may reduce the construction cost.

a construction method for impervious concrete for an MBBR water treatment process structure, comprising:

SO1: fabricating and installing reinforcements and installing inner and outer mounting frames outside the reinforcements;

S02: fabricating a construction formwork and setting a bottom construction formwork and a support frame on cushion concrete; installing a wall construction formwork on the mounting frame by hoisting;

and S03: arranging a plurality of embedded parts on reinforcements and tightening a wall construction formwork through the embedded parts.

Embedded tie bars are used as reinforcing parts of tank wall formwork, which form a tank wall formwork system together with reinforcing main girder, small beam and formwork. Therefore, the quantity and distribution of embedded parts are obtained according to the checking calculation of strength, stiffness and stability, and the calculation basis is Technical Code for Safety of Forms in Construction (JGJ162-2008), Code for Design of Concrete Structures (GB50010-20103), Load Code for the Design of Building Structures (GB 50009-2012) and Codefor Design ofSteel Structures (GB 50017-2003).

The details are as follows: 1. determine the engineering parameters: wall thickness, wall length, wall height and strength grade of concrete.

Name ofnewly poured concrete Tank wall Thickness of newly poured wall concrete wall (mm)

Calculated height of concrete wall Calculated length of concrete wall (mm) (mm)

2. determine the load combination according to Technical Code for Safety of Forms in Construction (JGJ162-2008).

Specification for Technical Codefor Safetyof Gravity density of concreteyA 24 calculation basis of Forms in Construction (kN/m") lateral pressure (JGJ162-2008)

Initial setting tim eof Additive influence 3correction newly poured concrete to 4 coefficient 1 (h)

Concrete slump influence correction 1 Concrete placing speed V (m/h) 2 coefficient P2

Total height from the calculation position of lateral pressure of concrete to the top surface of newly poured 6 concrete H (m)

Standard value of lateral pressure of newly poured min{0.22ctopIp2V1/i12 concrete on formwork G4k (kN/m2 24x6=min29.868, 144=29.868kN/m 2

Standard value of load on vertical formwork when dumping concrete Q3k (kN/m2 )

3. formwork combination design.

Arrangement form of small Vertical Cantilever length of left 50 beam formwork (mm)

Spacing between small beams 150 Cantilever length of small beam 200 (mm) end (mm)

Spacing between main girders 400 Cantilever length of main girder 100 (mm) end (mm)

Transverse spacing between 200 Vertical spacing between split 400 split bolts (mm) bolts (mm)

4. panel checking calculation (1) strength checking calculation (2) disturbance checking calculation

5. small beam checking calculation (1) strength checking calculation (2) disturbance checking calculation (3) bearing reaction calculation.

6. main girder checking calculation (1) strength checking calculation (2) disturbance checking calculation.

7. split bolt checking calculation (1) axial tension.

After the above checking calculations are completed, the calculated value may be compared with the design value. If the stress does not meet the checking calculation requirements, the formwork system needs to be strengthened correspondingly; and if the calculated value is much lower than the design value, it means that the formwork combination meets the requirements but is not economical. The layout may be adjusted appropriately. Repeated checking calculation is carried out again to meet the design value requirements and achieve economic optimization.

S04: for concrete placing, adopting one-time continuous placing, wetting and curing after concrete condensation, and curing for at least the specified period of time; after curing, stripping, and controlling the temperature difference between the temperature of concrete surface layer and the ambient temperature to be within the specified range when the formwork is removed. In some embodiments, the designated time may be set to 14 days and nights, and the designated temperature difference range is 15°C.

In the construction method disclosed above, the construction formwork is connected and fastened by reasonably setting embedded parts, the construction formwork is formed by continuous placing, and the concrete curing and formwork removal are carried out according to the set conditions, which may tighten the construction formwork, ensure the construction to meet the requirements for surface degree, and ensure the overall concrete quality after construction.

In the technical solution, before wall construction of the structure, foundation treatment such as leveling and strengthening of foundation are carried out, cushion concrete is poured as a floor, and the structure is constructed on the basis of cushion concrete. Specifically, the construction formwork is set before the construction of the structure, and the following feasible solutions are adopted. The setting of a bottom construction formwork on the cushion concrete comprises the following steps:

putting a baseline on the cushion concrete to determine an installation position of the bottom construction formwork, connecting and fixing the bottom construction formwork through the support frame, and testing and adjusting the bottom construction formwork to the design verticality.

It may be seen that the underwater pressure is directly proportional to the depth of water, and the water pressure at the bottom of cushion concrete and structure is the largest. When the structure is a high tank wall structure, the bottom joint between cushion concrete and structure is prone to water seepage. Therefore, adopting the above method to set the benchmark on the bottom concrete and setting the bottom construction formwork strictly according to the baseline may improve the rigor of subsequent concrete placing construction, and there are no construction joints and other structures between the completed structures and the bottom concrete, with good integration and higher anti-seepage performance.

In the construction formwork setting mode disclosed in the technical solution, because there are several construction formworks, which are arranged in a continuous laying mode when laying, it is necessary to make the stability and flatness of adjacent construction formworks correspond to each other. A concrete and feasible solution is adopted in the embodiment: a plurality of layers of construction formworks are arranged from bottom to top, each layer of construction formwork is provided with an independent support frame, the support frame of the upper layer of construction formwork is erected on the support frame of the lower layer of construction formwork, and the adjacent two layers of construction formworks are strengthened by reinforcing parts. The function of reinforcing parts is to fix the upper and lower layers of support frames so that the relative stability of the upper and lower layers of construction formworks is stronger and the surface consistency of concrete after construction molding is better.

In order to avoid slurry leakage in the construction process, the setting mode of construction formwork is optimized, and the following specific feasible scheme is given here as an example: when installing construction formwork, a seal strip is provided at the joint between adjacent construction formworks. The seal strip is made of flexible material, which may fully fill the transverse joint and the longitudinal joint between construction formworks to achieve the sealing effect.

Preferably, the seal strip may be a sponge strip, the thickness of the sponge strip may be 5 mm, two adjacent construction formworks are used to clamp the sponge strip, and a seal tape may also be used for sealing.

The embedded parts disclosed in the technical solution are used for connecting and fastening construction formworks, the embedded parts comprise an embedded tie bar 1, both ends of the embedded tie bar are provided with a thread and are connected with a tapered head 4, both ends of the embedded tie bar are also connected with an extension tie bar 2 through the tapered head, the embedded tie bar is buried in a wall with concrete placing, and the extension tie bar is used for tightening the construction formwork and the support frame. In specific application, the tapered head is provided with connecting through holes, the length of the tapered head after being arranged at both ends of the embedded tie bar is just equal to the thickness of the wall, the narrow end of the tapered head faces the concrete wall, the wide end of the tapered head faces the construction formwork, the construction formwork is provided with corresponding connecting holes, and the connecting holes are matched and fastened with the extension tie bar.

In some embodiments, the length of the embedded tie bar is 250 mm, the narrow end diameter of the tapered head is 30 mm, and the wide end diameter is 40 mm.

After construction, the extension tie bar may be removed from the tapered head by rotating the extension tie bar; however, it is necessary to use sleeve tools to remove the tapered head. After the tapered head is removed, residual holes appear on the construction surface, which may be filled with concrete prepared with the same grade of cement.

The embedded parts are arranged inside the poured concrete wall and penetrate through the concrete wall. In order to ensure the effect of preventing water seepage, the structure of the embedded tie bar is optimized. Specifically, the following feasible scheme is given as an example: the embedded tie bar is provided with a waterstop 3, and the waterstop is sleeved on the embedded tie bar and is at least 2 cm higher than the surface of the embedded tie bar. When a waterstop is arranged, the hole where the embedded tie bar is located is sealed by the waterstop, and the joint between the waterstop and the embedded tie bar has a fully welded sealing structure, thus preventing water from penetrating from one side of the wall to the other side through the embedded tie bar hole.

Preferably, a circular thin sheet is arranged at the middle position of the embedded tie bar as a waterstop, and the thin sheet has a thickness of 3 mm and is made of steel plate. If the thickness of the tank wall is large and the length of the embedded tie bar is long, multiple waterstops may be set on the embedded tie bar.

As the walls under construction are generally high walls, after the construction formwork is set up, impurities may enter the placing space and affect the construction quality, so it is necessary to clean the placing space in advance, and the following optimized and specific feasible scheme is given as an example: at the root of the wall construction formwork, a cleanout is set at every specified distance. In some embodiments, the specified distance may be set to 10 m.

In order to ensure the smooth and clean construction surface in the later period and avoid damaging the surface degree of concrete construction during formwork removal, the following feasible technical solution is given as an example: the construction formwork is coated with a stripping agent, which is brushed before concrete placing so that it is easier to remove the construction formwork in the later period and protect the concrete surface after stripping from damage.

Strictly controlling the process of concrete placing and vibrating is the key to improve the quality of concrete placing. Here, the optimization restriction is carried out, and the following concrete and feasible solutions are adopted in the embodiment: in the process of concrete placing, the height of formed concrete is less than or equal to 0.5 m per hour.

The raw materials for concrete used are limited to achieve better construction effect, and the following optimized and specific feasible scheme is given as an example: using slag cement greater than or equal to P42.5 for preparing concrete.

The above-mentioned content has carried on the concrete elaboration to the construction method, and a specific construction case is listed for illustration.

Nanming River Water Environment Comprehensive Improvement Project covers an area of about 39,933 square meters, with a total construction scale of 240,000 m 3/d and 30,000 m 3/d in the near future, which will be implemented in stages. In the Project, the high-efficiency settling tank, aerated grit chamber, biochemical tank and lift pump well are all reinforced concrete structures, with a bottom height of 5-10 m respectively, belonging to high tank wall, the design strength of concrete is C30, and the impermeability grade is P6. The process is Norwegian advanced MBBR (Biofilm Reactor) water treatment process.

Before construction, carry out preparatory work, fabricate and install reinforcements, erect internal and external frames, and report the concrete consumption plan to the concrete mixing station in advance when the formwork is to be poured after formwork support has passed acceptance, plan the route, prepare the corresponding mechanical equipment and tools, and prepare an alternative scheme for concrete placing to ensure continuous concrete placing.

The main materials for construction are shown in Table 1:

Table 1 Material Quantity Table

SN Name Model Unit Quantity 3 1 Sleeper 160x240x2500 m 15 3 2 Square timber 140x140x600 m 200 3 Three-section split screw (p14 PCs. 34,830 4 Bamboo plywood 122 cm*244 cm*1.8 cm m2 5,000 5 Steel pipe (48 mm Ton 30

The main machinery and equipment for construction are shown in Table 2:

Table 2 List of Machinery and Equipment

SN Name Model Unit Quantity 1 Automobile delivery pump HB60C Set 2 2 Crane 50t Set 2 3 Dump truck 15 t Set 4 3 4 Air compressor 9m Set 1 5 Electric saw Set 1 6 Electric planer Set 1

Immersion vibrator (70 mm /p100 mm Set Four for 7 each 8 Rebar bender 6 mm-40 mm Set 2 9 Rebar cutter 6 mm-40 mm Set 2 10 Transformer 400 KVA Set 1 11 Electric welding machine Set 5 12 External vibrator Set 2

In order to ensure the construction quality of concrete, wood formwork is used in the Project to achieve the effect of fair-faced concrete. The support system is provided with a square timber and fastener scaffold, the split bolt is fixed by double rows of steel pipes, the split bolt is three-section impermeable screw drawing rod, the middle section plus the steel-plastic tapered head is equal to the wall thickness, and the screw length at both ends is the sum of the supporting thicknesses of formwork, steel pipe and square timber. The turnover times of formwork for main structures are not over three times. If corners are damaged during the turnover of formwork, they must be treated before being reused. Formwork that cannot guarantee the surface quality of concrete should be discarded, and both ends of split bolts may be reused, thus saving material cost.

Installation sequence of bottom formwork: surveying and setting-out, and fixing points- assembling formwork -- adjusting elevation, straightening, supporting and fixing -- binding reinforcements of floor -- installing hanging formwork on reserved platform of tank wall.

On the surface of cushion concrete, use instruments to put in the baseline of formwork installation, so as to place, support and fix formwork, and adjust the verticality of formwork is by a horizontal ruler. The foundation is supported by a 1.2 cm thick plywood suspension formwork, that is, the wooden formwork is fixed on the 8 cmx5 cm square timber, and the square timber is supported on the support system of the lower formwork and reinforced with steel pipes, and then the steel pipe support frame is fixed on the foundation pit wall with a square timber to avoid sliding.

Installation of tank wall formwork: according to the structural size and concrete placing level height, the formwork should be fabricated in advance in the wood processing room, and be installed and fixed in place on site; and when assembling longitudinal and transverse formwork joints, seal strips should be clamped between seams, and the seal strips should be flush with the formwork surface to prevent slurry leakage.

During on-site operation, after the reinforcement is bound and passes accepted, the formwork is supported. The formworks on both sides are drilled at corresponding positions. Formworks should be installed in blocks: first, erect one side of the formwork and then simply fix it, select split bolts that meet the requirements of wall thickness to assemble the formwork firmly, put the assembled bolts into the drilled formwork holes, then support the formwork on the other side, align the bolts with the drilled holes, and fix them temporarily, and so on; when all the wall formwork in one wall or a certain area is supported, carry out unified reinforcement and correction to ensure that the flatness and verticality of the wall meet the specification requirements.

When setting the embedded parts before placing, the final setting scheme is obtained through the calculation model, which specifically includes:

1. establishing formworks model in computer;

2. setting corresponding parameters in the model, so that the model may achieve the same simulation effect as the actual one;

3. carrying out design checking calculation according to the set parameters, to check whether the emulation verification construction effect meets the safety requirements;

4. optimizing the solution according to the checking result, and repeat the 3rd step until the model may meet the safety requirements;

and 5. determining the design scheme and generating the actual setup scheme.

During the construction, the tank wall is poured at one time, and the formwork is directly located on the floor. The tank wall formwork should be installed after binding of reinforcements and installation and fixing of various embedded parts, and seal strips should be arranged between the surface of the reserved platform of the tank wall and the formwork to prevent slurry leakage. During concrete vibrating, master the vibration time, insert the vibrator quickly and pull it slowly, so as to avoid die expansion or vibration leakage caused by excessive vibration. Concrete placing should be carried out in layers and sections, and the next section of concrete must be started before the initial setting of the previous section of concrete to ensure the continuity of concrete placing.

In order to ensure the smoothness of the wall and the convenience of formwork removal, the formwork must be painted with a stripping agent before installation, and the stripping agent should be painted evenly. At the same time, in order to better clean up the sundries in the formwork, a cleaning port is set at the root of the formwork in the tank wall every 10 m. A 5 mm thick sponge strip is clamped at the joint between formworks to ensure that the joint between formworks is tight and does not leak slurry.

All the places where the support is in direct contact with soil are padded with square timber with a thickness of 4 cm to prevent the support system from sinking.

During concrete placing, the foundation and side wall concrete of each structure should be poured by an automobile pump. Another pump is prepared at the construction site for standby, so as to prevent interruption due to pouring interruption caused by mechanical failure. When pouring wall concrete, a blanking bucket should be set on the wall at an appropriate distance. When pouring concrete, the height of formed concrete should be strictly controlled to be no more than 0.5 m per hour. Spare concrete should be stored and equipped at any time at the construction site along with the pouring progress, so as to prevent the problem of interruption between adjacent two layers caused by untimely incoming of concrete. When the strength of concrete is less than 1.2 N/mm 2 after pouring, it is forbidden to vibrate or exert any external force to the concrete.

In view of the possible problems in concrete placing, analyze the causes and find out the countermeasures to ensure the smooth progress of concrete placing. The countermeasure table is shown in Table 1:

Table 1 Table of Guarantee Countermeasures for Concrete Construction

SN Phenomena Cause analysis Countermeasures 1. The moisture content of sand 1. Re-measure the moisture content of The slump of and gravel is not speculated, sand and gravel and adjust the amount concrete mixture is which leads to measurement of water added; too small, which is errors; 2. Adjust the concrete mix proportion; 1 prone to bleeding, 2. The original mix proportion is 3. Repair and correct the metering slurry leakage and not suitable for material change; device of the mixer; and segregation, 3. The cooling water device of the 4. Reduce the amount of additive, and resulting in pipe mixer is faulty; and add proper amount of cement to the blockage. 4. The consumption of fluidizing mixed mixture and cure it evenly. agent is too large. 1. The moisture content of sand 1. Re-measure the moisture content of and gravel is not measured sand and gravel and adjust the amount accurately, which leads to errors of water added; in water measurement; 2. Adjust the concrete mix proportion; The slump of 2. The original mix proportion is 3. Calibrate the metering device of the concrete mixture is not suitable for material change; mixer; and too small, whichchne mirad 2 leadstodifficultyin 3. The cooling water device of the 4. Appropriately increase the amount transportation and mixer is faulty; and of additive, and add mortar or even blockage. 4. The amount of water-reducing high-efficiency water-reducing agent agent is insufficient. with the same mix proportion as concrete to the mixed mixture, and cure it after mixing well, without adding water. 1. The original mix proportion is 1. Adjust the concrete mix proportion; The workability of not suitable due to the change of 2. Appropriately increase sand ratio; concrete mixture is materials; and 3 poor, such as 2. The sand ratio is small; and 3. Add ground fly ash or zeolite layering and stone 3. The content of fine powder mineral powder, etc. exposure. below 0.15 mm in concrete is small.

After being condensed, the concrete of the tank wall should be cured immediately and fully kept moist. The curing time should not be less than 14 days and nights. The temperature difference between the surface temperature of the tank wall and the surrounding air temperature shall not exceed 15°C during stripping.

When the concrete strength meets the requirements of stripping, the formwork should be removed. During stripping, first remove the external tie bolts, and collect and pile them up to the upper part of the foundation pit, so as to avoid damage caused by stripping and not affect the next use. After the bolts are removed, remove and clean the formwork, and then remove the tapered head. After construction, the surface of the waterstop bolts should be clean and should not be exposed to rain, so as to prevent rusting. Remove the conical head with a standard sleeve inserted into the conical head for removal. Remove the tapered head by inserting a standard sleeve into the tapered head.

The method disclosed in the present embodiment is adopted in the construction project, and the following beneficial effects are achieved:

1. by reinforcing the formwork with three-section combined tool waterstop split bolts, the loss rate of the formwork will be reduced, the formwork may be removed once in a large area, and the time cost will also be reduced; and the tie bars and tapered heads at both ends may be reused, which may effectively save resources, save energy and protect the environment, reduce cost and reduce project cost.

2. with the use of new steel plug, there is almost no leakage point at the tie bar, which reduces the post-treatment work.

3. the security calculation software is used to model and determine the strength, which reduces a large number of replication calculation processes. The process management is strengthened, which reduces the time and cost of leakage point plugging in the later period.

4. taking the number of waterstop tie bars used in the tank structure of this treatment plant as an example, the total number of tie bars used is 34,830.

The purchase price of traditional waterstop screw is RMB 4.2 + RMB 1 (average price) (014 is adopted, the middle waterstop plate model is 100*100*3, the wall thickness is mainly 600, and price of the rubber cushion block is RMB 0.5/piece). The labor cost is RMB 6.1. The cost of waterstop tie bar rod in the plant area is RMB (4.2+1+6.1)*34,830=393,579.

Novel waterstop screws are adopted. The price of the middle section of the waterstop screw is RMB 2.2, the price of tie bars at both ends is RMB 1.4 (the wall thickness is 600, and the total length of waterstop tie bar is wall thickness + 50 cm), and the price of steel-plastic tapered head is RMB 0.7/piece. The later reduction procedures for the novel steel-plastic tapered head are: manual cutting and hole digging. Therefore, the labor cost is adjusted to RBM 4.36. The tie bars at both ends of the novel steel-plastic tapered head screw and the steel-plastic tapered head may be reused and amortized four times. The cost of the novel waterstop tie bar in the plant area is 2.2*348,30+(348,30/5* (1.4+1.4)) +4.36*348,30=247,989.6.

The direct cost saved by the novel steel-plastic tapered head screw is RMB 393,579-247,989.6 = 145,589.4.

Hence, the construction method has achieved excellent construction effects and economic benefits.

The above are embodiments enumerated for the present invention, but the present invention is not limited to the above optional embodiments. Those skilled in the art may arbitrarily combine the above embodiments with each other according to the above embodiments to obtain many other embodiments, and anyone may obtain various other forms of embodiments according to teachings of the present invention. The above specific embodiments should not be construed as restriction to the scope of protection of the present invention. The scope of protection of the present invention should be subject to the scope defined in the claims, and the description may be used to interpret the claims.

The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement or any form of suggestion that such prior art forms part of the common general knowledge.

It will be understood that the terms "comprise" and "include" and any of their derivatives (e.g. comprises, comprising, includes, including) as used in this specification, and the claims that follow, is to be taken to be inclusive of features to which the term refers, and is not meant to exclude the presence of any additional features unless otherwise stated or implied.

In some cases, a single embodiment may, for succinctness and/or to assist in understanding the scope of the disclosure, combine multiple features. It is to be understood that in such a case, these multiple features may be provided separately (in separate embodiments), or in any other suitable combination. Alternatively, where separate features are described in separate embodiments, these separate features may be combined into a single embodiment unless otherwise stated or implied. This also applies to the claims which can be recombined in any combination. That is a claim may be amended to include a feature defined in any other claim. Further a phrase referring to "at least one of' a list of items refers to any combination of those items, including single members. As an example, "at least one of: a, b, or c" is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c.

Claims (10)

1. A construction method for impervious concrete for an MBBR water treatment process structure, characterized by comprising the following steps:

fabricating and installing reinforcements and installing inner and outer mounting frames outside the reinforcements;

fabricating a construction formwork and setting a bottom construction formwork and a support frame on cushion concrete; installing a wall construction formwork on the mounting frame by hoisting;

arranging a plurality of embedded parts on reinforcements and tightening the wall construction formwork through the embedded parts; and

for concrete placing, adopting one-time continuous placing, wetting and curing concrete after condensation, and curing for at least the specified period of time; after curing, stripping, and controlling the temperature difference between the temperature of concrete surface layer and the ambient temperature to be within the specified range during stripping.

2. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 1, characterized in that the setting a bottom construction formwork on the cushion concrete comprises the following steps:

putting a baseline on the cushion concrete to determine an installation position of the bottom construction formwork, connecting and fixing the bottom construction formwork through the support frame, and testing and adjusting the bottom construction formwork to the design verticality.

3. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 2, characterized in that

a plurality of layers of construction formworks are arranged from bottom to top, each layer of construction formwork is provided with an independent support frame, the support frame of the upper layer of construction formwork is erected on the support frame of the lower layer of construction formwork, and the connection between two adjacent layers of construction formworks are strengthened by reinforcing parts.

4. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 1, characterized in that during the installation of construction formworks, a seal strip is provided at a joint between adjacent construction formworks.

5. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 1, characterized in that

the embedded part comprises an embedded tie bar (1), both ends of the embedded tie bar are provided with a thread and are connected with a tapered head (4), both ends of the embedded tie bar are also connected with an extension tie bar (2) through the tapered head, the embedded tie bar is buried in a wall with concrete placing, and the extension tie bar is used for tightening the construction formwork and the support frame.

6. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 5, characterized in that

the embedded tie bar is provided with a waterstop (3), and the waterstop is sleeved on the embedded tie bar and is at least 2 cm higher than the surface of the embedded tie bar.

7. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 1, characterized in that

at the root of the wall construction formwork, a cleanout is set at every specified distance.

8. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 1, characterized in that

the construction formwork is coated with a stripping agent.

9. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 1, characterized in that

in the process of concrete placing, the height of formed concrete is less than or equal to 0.5 m per hour.

10. The construction method for impervious concrete for an MBBR water treatment process structure according to claim 1, characterized in that

slag cement greater than or equal to P42.5 is used for preparing concrete.