CN116122316A

CN116122316A - Cofferdam bottom sealing construction method

Info

Publication number: CN116122316A
Application number: CN202310132539.1A
Authority: CN
Inventors: 朱家焕; 章新生; 丁得志; 周海峰; 闫鹏敏; 李庆斌; 曹少华; 俞小进; 张俊辉
Original assignee: China Railway Communications Investment Group Co ltd; China Tiesiju Civil Engineering Group Co Ltd CTCE Group; Fifth Engineering Co Ltd of CTCE Group
Current assignee: China Railway Communications Investment Group Co ltd; China Tiesiju Civil Engineering Group Co Ltd CTCE Group; Fifth Engineering Co Ltd of CTCE Group
Priority date: 2023-02-17
Filing date: 2023-02-17
Publication date: 2023-05-16

Abstract

The invention provides a cofferdam back cover construction method, which comprises the following steps: dredging the river bed in the steel cofferdam; stacking sand bags at distribution points of the steel cofferdam, and arranging an anti-segregation conduit on the upper side of the sand bags for concrete pouring and bottom sealing; the method comprises the steps of arranging a buoyancy tank on a water surface, arranging a concrete detector on the buoyancy tank, lowering a probe of the concrete detector through a plumb line, and monitoring the concrete pouring height in real time to control the elevation of the top surface and the position of a blanking point until the cofferdam bottom sealing operation is completed. Through piling up the sand bag in cloth point department, can prevent the concrete that segregation pipe falls to cushion, prevent that the concrete from mixing because impact force and super thick silt, lead to the unable dense whole that forms of concrete to influence construction quality, further through the portable detection method of buoyancy tank, concrete detector and plumb combination, improved cofferdam back cover elevation control's precision, reduced the secondary leveling process for construction period, the unloading position of being convenient for control simultaneously guarantees construction quality.

Description

Cofferdam bottom sealing construction method

Technical Field

The invention relates to the technical field of cofferdam construction, in particular to a cofferdam back cover construction method.

Background

The cofferdam is a temporary enclosure structure built for building a permanent hydraulic facility in hydraulic engineering construction. The water and soil are prevented from entering the building construction position, so that water is drained in the cofferdam, a foundation pit is excavated, and the building is constructed.

Among the prior art, to the underwater back cover construction project of steel cofferdam, because the environment is complicated under water, visual distance is limited, can't monitor and control the top surface elevation of the retarded soil of back cover, simultaneously because super thick silt layer is different with the volume weight of concrete, at the back cover in-process, silt layer can pile up along with back cover concrete self-flow effect, after pile up too high, back cover concrete top surface will form the wave, and local elevation is too high, and partial position effective thickness is not enough, influences construction quality.

Disclosure of Invention

Aiming at the defects of the prior art, the invention aims to provide a cofferdam back cover construction method, which aims to solve the technical problem of poor construction quality in the prior art.

In order to achieve the above object, the present invention is achieved by the following technical scheme: the cofferdam back cover construction method is applied to thick silt layer underwater cofferdam construction and comprises the following steps:

dredging the river bed in the steel cofferdam;

stacking sand bags at distribution points of the steel cofferdam, and arranging an anti-segregation conduit on the upper side of the sand bags for concrete pouring and bottom sealing;

setting a buoyancy tank on the water surface, setting a concrete detector on the buoyancy tank, lowering a probe of the concrete detector through a plumb line, and monitoring the height of concrete in the process of pouring the concrete to cover the bottom in real time based on the lowering length of the plumb line and the detection result of the concrete detector until the height of the concrete at the distribution point reaches a preset standard value;

and moving the plumb line, measuring the concrete height of the vicinity of the concrete height reaching the preset standard value, moving the anti-segregation guide pipe to a blanking point of which the concrete height reaches the preset value, inserting the anti-segregation guide pipe into concrete with a preset depth to perform concrete pouring back cover until the concrete height of the blanking point reaches the preset standard value, and repeating the steps of moving the anti-segregation guide pipe and performing concrete pouring back cover until the cofferdam back cover operation is completed.

Compared with the prior art, the invention has the beneficial effects that: according to the method, firstly, dredging treatment is carried out on a riverbed, concrete pouring back cover is convenient to carry out subsequently, sand bags are piled up at distribution points before pouring, concrete falling of an anti-segregation conduit can be buffered, concrete cannot form a compact whole due to mixing of impact force and ultra-thick sludge is prevented, construction quality is affected, a buoyancy tank is further arranged on a water surface, a concrete detector is arranged on the buoyancy tank, a probe of the concrete detector is lowered through a plumb line, real-time detection is carried out on the height of the concrete in the process of pouring the back cover based on the lowering length of the plumb line and the detection result of the concrete detector, so that the top surface height of the concrete can meet design requirements, the concrete height near the distribution points is further detected through the method of lowering the plumb line, meanwhile, a corresponding secondary discharging point is found out based on the pouring height of the poured concrete, the fact that concrete is piled up due to extrusion between two times of concrete due to the fact that the separation distance of the two discharging points is far, local failure is caused, the concrete is mixed into the back cover concrete layer, the concrete is prevented from being mixed into the layer, the concrete layer is inserted into the preset depth, and the construction quality can be guaranteed.

According to an aspect of the above technical solution, the method further includes the steps of repeating the steps of moving the segregation preventing pipe to a discharging point where the height of the concrete reaches a preset value, and inserting the segregation preventing pipe into the concrete of a preset depth to perform concrete pouring and bottom sealing, and the method further includes:

setting a slag bucket to detect sludge at the edge of the concrete in real time and cleaning the sludge through a sludge suction pump.

According to an aspect of the foregoing technical solution, before the step of completing the cofferdam bottom sealing operation, the method further includes:

and a dredging pump pipe is arranged on one side of the steel cofferdam, which is far away from the distribution point, so as to clean accumulated sludge at fixed points.

According to an aspect of the foregoing technical solution, the method further includes:

and setting retarder in the concrete.

According to one aspect of the above technical solution, the step of dredging the riverbed in the steel cofferdam specifically includes:

the sludge in the steel cofferdam is cleaned in a large area through a long-arm excavator, a grab bucket and a hydraulic dredging pump;

and after the hydraulic dredging pump agitates the sludge in the steel cofferdam, the sludge in the steel cofferdam is cleaned by a high-pressure gas lift circulating device.

According to an aspect of the above technical solution, after the step of cleaning the sludge in the steel cofferdam by a high pressure gas lift circulation device, the method comprises:

and cleaning the sludge on the outer wall of the steel casing and the inner wall of the steel cofferdam through a high-pressure water gun shovel.

According to an aspect of the foregoing technical solution, after the step of cleaning the sludge on the outer wall of the steel casing and the inner wall of the steel cofferdam by the high-pressure water gun shovel, the method further includes:

and lowering the plumb line along the outer wall of the steel pile casing and the inner wall of the steel cofferdam, and detecting a cleaning result according to the lowering height of the plumb line.

According to one aspect of the technical scheme, one side of the discharge hole of the anti-segregation guide pipe is provided with a conical buffer plate, and the conical slope rate of the conical buffer plate is 2%.

According to an aspect of the foregoing technical solution, the preset value a satisfies: 0.75b > a > 0.25b; wherein b is the preset standard value.

According to an aspect of the foregoing technical solution, the preset depth c satisfies: c > 30cm.

Drawings

FIG. 1 is a flow chart of a cofferdam back cover construction method in an embodiment of the present invention;

FIG. 2 is a diagram showing distribution of distribution points and blanking points according to an embodiment of the present invention;

FIG. 3 is a schematic diagram illustrating a bottom sealing operation according to an embodiment of the present invention;

the invention will be further described in the following detailed description in conjunction with the above-described figures.

Detailed Description

In order that the invention may be readily understood, a more complete description of the invention will be rendered by reference to the appended drawings. Several embodiments of the invention are presented in the figures. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

It will be understood that when an element is referred to as being "mounted" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "left," "right," and the like are used herein for illustrative purposes only.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

Referring to fig. 1, a flow chart of a cofferdam bottom sealing construction method in an embodiment of the invention is shown, comprising the following steps:

and S100, dredging the riverbed in the steel cofferdam. Specifically, in this step, concrete is in the whereabouts in-process, because its impact force, can mix with super thick silt, leads to the concrete unable to form to close whole, influences construction quality, so after the completion of steel cofferdam is inserted and is beaten and first layer steel support installation is accomplished, need carry out silt clearance to the cofferdam.

Preferably, in this embodiment, the step S100 specifically includes:

step S101, cleaning sludge in the steel cofferdam in a large area through a long-arm excavator, a grab bucket and a hydraulic dredging pump;

and step S102, after the hydraulic dredging pump agitates the sludge in the steel cofferdam, cleaning the sludge in the steel cofferdam through a high-pressure gas lift circulating device. Aiming at an ultra-thick silt geological layer, the three dredging modes of a long-arm dredger, a hydraulic dredging pump and a dredger can be utilized to jointly provide a good working environment for high-pressure gas lifting circulation dredging and arch lifting, and the high-pressure gas lifting circulation dredging device has the functions of cleaning silt and stirring the silt in the steel cofferdam, so that the high-pressure gas lifting circulation device can clean the silt, and the working efficiency of the high-pressure gas lifting circulation device is improved.

Further, in some application scenarios of this embodiment, because in the dredging process, there is the dead angle in steel sheet pile inside wall, structure corners clearance such as pile foundation pile casing outer wall on water, can't clear up, easily lead to bottom sealing concrete and structure bonding degree end, cofferdam anti-floating ability is not enough, easily appears safety in production accidents such as cofferdam gushing after the cofferdam draws water, in this embodiment, above-mentioned step S100 still includes:

and step S103, cleaning sludge on the outer wall of the steel casing and the inner wall of the steel cofferdam through a high-pressure water gun shovel. Specifically, in this embodiment, the cleaning operation is mainly implemented by controlling the high-pressure water gun shovel by a diver, and preferably, in this embodiment, to ensure the cleaning effect, after step S103, the method further includes:

and step S104, the plumb line is lowered along the outer wall of the steel casing and the inner wall of the steel cofferdam, and the cleaning result is detected according to the lowering height of the plumb line. And (3) checking the outer wall of the steel pile casing and the inner wall of the steel sheet pile through plumb lines, and after the steel pile casing and the inner wall of the steel sheet pile are checked to be qualified, organizing and starting the bottom sealing concrete pouring.

And S110, stacking sand bags at distribution points of the steel cofferdam, and arranging an anti-segregation conduit on the upper side of the sand bags to perform concrete pouring and bottom sealing. Specifically, in this step, in order to further prevent the concrete from being mixed with the ultra-thick sludge due to the impact force, a sand bag is provided at the distribution point for buffering before the discharging operation of the concrete pouring back cover is performed, preferably, in this embodiment, the laying diameter of the sand bag is 3m, and in order to ensure that the effective thickness of the back cover concrete meets the requirement, the stacking height of the sand bag cannot invade the bottom elevation of the back cover concrete.

Preferably, in this embodiment, in order to reduce the impact force of concrete dropping, a conical buffer plate is disposed at one side of the discharge hole of the anti-segregation conduit, and the conical slope rate of the conical buffer plate is 2%.

And step S120, setting a buoyancy tank on the water surface, setting a concrete detector on the buoyancy tank, lowering a probe of the concrete detector through a plumb line, and monitoring the height of concrete in the process of pouring the concrete to seal the bottom in real time based on the lowering length of the plumb line and the detection result of the concrete detector until the height of the concrete at the distribution point reaches a preset standard value. Specifically, in the prior art, the height of the back cover in the process of pouring the concrete is generally controlled by a traditional plumb method, the accuracy is low, the construction experience is mainly depended, and the accuracy of the height control of the back cover concrete in the process of pouring the concrete can be greatly improved by matching a concrete detector on the basis of the traditional plumb method, so that the construction quality is improved. In some application scenarios of this embodiment, the plumb and the concrete detector are utilized to pass through the middle part of the annular buoyancy tank, and the extension length of the plumb and the concrete detector is positioned by controlling the water level elevation, so as to achieve the control of the bottom sealing concrete elevation. The concrete detector is used for positioning the elevation of the concrete by displaying red when contacting the concrete and yellow when contacting the slurry.

And S130, moving the plumb line, measuring the concrete height of the vicinity area where the concrete height reaches the preset standard value, moving the anti-segregation guide pipe to a discharging point where the concrete height reaches the preset value, and inserting the anti-segregation guide pipe into concrete with the preset depth to perform concrete pouring back cover until the height of the concrete at the discharging point reaches the preset standard value. Specifically, in the conventional cofferdam back cover construction operation, the concrete pouring of the whole bottom surface is completed by moving the blanking conduit of the concrete for many times, but the setting of the blanking points in the conventional construction operation is usually based on experience, because the underwater back cover is invisible, the arrangement of the position of the blanking points is improper, the local failure of the concrete is easily caused, the local concrete exceeds the standard height due to the too close distance between the two blanking points, and the local thickness of the concrete is possibly insufficient due to the too far distance between the two blanking points. In the step, the preset standard value, namely the preset top surface height of the back cover concrete, can be obtained through horizontal plane-fixed height, and the concrete height detection is carried out through setting plumb lines and a concrete detector, so that the accuracy of the control of the back cover elevation of the cofferdam is improved, the secondary leveling procedure is reduced, the construction period is shortened, the position of the next discharging point is determined based on the poured concrete top surface height (preset value) when the height of the discharging point reaches the preset standard value, the underwater silt cleaning depth and the sheet stone filling procedure are reduced, the mixing thickness of the back cover concrete and the silt is reduced, the effective thickness of the back cover concrete is improved, the economic benefit is increased, and meanwhile, the construction quality is ensured. Preferably, in the present embodiment, the preset value a satisfies: 0.75b > a > 0.25b; wherein b is the preset standard value, and the preset depth c satisfies the following conditions: c > 30cm.

And step S140, repeating the steps of moving the anti-segregation guide pipe to a blanking point when the height of the concrete reaches a preset value, and inserting the anti-segregation guide pipe into concrete with a preset depth to perform concrete pouring and bottom sealing until the cofferdam bottom sealing operation is completed. The distribution of the above-mentioned blanking points and the moving paths thereof are shown in fig. 2.

In addition, as shown in fig. 3, in the back cover construction process of the ultra-thick silt layer, in the later stage of the back cover construction of the ultra-thick silt layer, the ultra-thick silt is extruded above the concrete or covered by the bond of the concrete, and the dead weight of the concrete is balanced with the dead weight of the ultra-thick silt, so that the casting surface of the local concrete is too high, the local effective thickness is insufficient, and the back cover surface is wavy or the effective thickness of the back cover is insufficient after the back cover is completed.

In this embodiment, to solve the above problem, in step S140, the method further includes:

and S150, setting a slag bucket to detect sludge at the edge of the concrete in real time, and cleaning the sludge through a sludge suction pump. Above-mentioned cloth point setting with sand bag is in cofferdam one side, survey the silt that the cofferdam corner compaction formed through setting up in the slag ladle of one side that the cofferdam regional keeping away from the cloth point in the back cover later stage, and utilize dredge pump and dredging pump line to carry out timely fixed point clearance to the compaction silt of detection, with reaching the bottom cover, survey simultaneously, the purpose of clearance simultaneously, the outside pressure of self-leveling concrete has been released, and the appearance that reduces the condition such as clamp mud has improved the stability and the back cover quality of cofferdam back cover, in addition, in this embodiment, in order to strive for time for dredging operation, can be through adding the retarder in the concrete, reach the effect of extension concrete initial setting time.

In summary, the cofferdam back cover construction method in the embodiment of the invention facilitates the subsequent concrete pouring back cover by dredging the riverbed, specifically increases the binding force between the back cover concrete and the steel casing and between the steel cofferdam inner wall by cleaning the mud attached to the outer wall of the steel casing and the inner wall of the steel cofferdam, reduces the probability of local surging after the cofferdam is pumped, improves the safety of the cofferdam back cover, reduces the underwater mud cleaning depth and the sheet stone replacement process by arranging the anti-segregation conduit and performing concrete pouring by arranging the conical buffer plate, reduces the mixing thickness of the back cover concrete and the mud, improves the effective thickness of the back cover concrete, increases the economic benefit, can buffer the concrete falling from the anti-segregation conduit by piling up a sand bag at a distributing point, prevents the concrete from being mixed with the ultra-thick mud, and leads to the concrete not forming a compact whole, thereby influencing the construction quality, further reduces the construction quality by arranging a floating box on the water surface, further reduces the probe of the concrete vertical line detector, reduces the depth of the underwater mud cleaning depth and the sheet stone replacement process by arranging the probe on the floating box, reduces the mixing depth of the sealing point, and further reduces the mixing thickness of the sealing point, and further reduces the mixing depth of the sealing point between the sealing point and the sealing point, and further reduces the requirements of the sealing point, and the concrete is more than the time. Can prevent equally that concrete from mixing with super thick silt, guarantee construction quality, in the back cover in-process, through adding retarder extension concrete initial setting time, for back cover in-process clearance silt strives for time, then surveys back cover concrete position with a sediment reel to erect the desilting pump line in advance and clear away by the fixed point by crowded silt, prevent that super thick silt from appearing and being crowded to the concrete top or by the condition of concrete bond coating, cause the back cover surface can be the wave, lead to the back cover surface too high or the condition that the back cover effective thickness is not enough.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above examples merely represent a few embodiments of the present invention, which are described in more detail and are not to be construed as limiting the scope of the present invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of the invention should be assessed as that of the appended claims.

Claims

1. The cofferdam back cover construction method is applied to thick silt layer underwater cofferdam construction and is characterized by comprising the following steps:

dredging the river bed in the steel cofferdam;

moving the plumb line, measuring the concrete height of the vicinity of the concrete height reaching the preset standard value, moving the anti-segregation guide pipe to a discharging point of which the concrete height reaches the preset value, and inserting the anti-segregation guide pipe into concrete with a preset depth to perform concrete pouring back cover until the concrete height of the discharging point reaches the preset standard value;

repeating the steps of moving the anti-segregation guide pipe to a discharging point when the height of the concrete reaches a preset value, and inserting the anti-segregation guide pipe into concrete with a preset depth to perform concrete pouring and bottom sealing until the cofferdam bottom sealing operation is completed.

2. The cofferdam back cover construction method of claim 1, wherein the steps of moving the anti-segregation guide pipe to a blanking point where the height of the concrete reaches a preset value and inserting the anti-segregation guide pipe into the concrete with a preset depth to perform concrete pouring back cover are repeated, and the method further comprises:

3. The cofferdam bottom-sealing construction method of claim 1, wherein before the step of completing the cofferdam bottom-sealing operation, the method further comprises:

4. The cofferdam back cover construction method as set forth in claim 1, further comprising:

and setting retarder in the concrete.

5. The cofferdam bottom sealing construction method of claim 1, wherein the step of dredging the riverbed in the steel cofferdam specifically comprises the following steps:

6. The cofferdam bottom sealing construction method of claim 5, wherein after the step of cleaning the sludge in the steel cofferdam by a high pressure gas lift circulation device, the method comprises:

7. The cofferdam back cover construction method of claim 6, wherein after the step of cleaning the sludge on the outer wall of the steel casing and the inner wall of the steel cofferdam by the high pressure water gun shovel, the method further comprises:

8. The cofferdam back cover construction method of claim 1, wherein a conical buffer plate is arranged on one side of a discharge hole of the anti-segregation guide pipe, and the conical slope rate of the conical buffer plate is 2%.

9. The cofferdam back cover construction method as set forth in claim 1, wherein the preset value a satisfies: 0.75b > a > 0.25b; wherein b is the preset standard value.

10. The cofferdam back cover construction method as set forth in claim 1, wherein said preset depth c satisfies: c > 30cm.