阅读说明：本技术 一种用于沉井水下封底的施工方法 (Construction method for underwater bottom sealing of open caisson ) 是由 刘朋 严成斌 何建峰 陈小东 石文杰 于 2021-10-13 设计创作，主要内容包括：本发明提供了一种用于沉井水下封底的施工方法,包括以下步骤：井底换填-埋设预埋排水管-安装降水。本发明利用预埋排水管道,先对井底进行降水处理再进行一期混凝土的浇筑,待混凝土强度达到要求后对降水管道进行封堵再进行二期混凝土浇筑至指定高程的方式对沉井进行封底,可降低混凝土标准,封底时可以不需要水下特制混凝土,只需混凝土满足抗渗要求即可,其次,降水后的井底便于施工,容易把握施工质量,防止后续井底漏水事件发生。(The invention provides a construction method for an underwater bottom sealing of an open caisson, which comprises the following steps: the method comprises the steps of well bottom replacement and filling, embedding and embedding of a drain pipe, and precipitation installation. According to the invention, the drainage pipeline is pre-embedded, precipitation treatment is firstly carried out on the shaft bottom, then first-stage concrete pouring is carried out, the caisson is sealed in a mode of plugging the precipitation pipeline after the concrete strength meets the requirement and then second-stage concrete pouring is carried out to a specified height, the concrete standard can be reduced, special underwater concrete is not needed during bottom sealing, only the concrete meets the anti-permeability requirement, and then the shaft bottom after precipitation is convenient to construct, the construction quality is easy to grasp, and the occurrence of subsequent shaft bottom water leakage events is prevented.)

1. A construction method for underwater bottom sealing of an open caisson is characterized by comprising the following steps: the method comprises the following steps:

shaft bottom replacement: cleaning the bottom of the open caisson, and then paving a permeable gravel layer (1);

burying an embedded drain pipe (4): embedding a pre-buried drain pipe (4) in the permeable gravel layer (1), and pouring the drain pipe (4) in the first-stage concrete (2) and the second-stage concrete (3) after precipitation is finished;

installing precipitation: the top of the pre-buried drain pipe (4) is connected with an external water pump, and a water stop valve (5) is arranged in the pre-buried drain pipe (4);

after the permeable gravel layer (1) is laid, the water suction pump is started, precipitation treatment is carried out on the bottom of the open caisson, the first-stage concrete (2) is poured, when the strength of the first-stage concrete (2) reaches more than 80%, the water suction pump and the water stop valve (5) are closed, and the second-stage concrete (3) is poured.

2. The construction method for the underwater back cover of the open caisson according to claim 1, wherein: in the first step, a high-pressure water gun is used for cleaning sludge at the bottom of the open caisson, an air suction dredge is used for discharging slurry, then a permeable gravel layer (1) is uniformly paved, and stone bricks (7) are arranged at the blade feet of the open caisson.

3. The construction method for the underwater back cover of the open caisson according to claim 1, wherein: the top of the pre-buried drain pipe (4) is higher than the top of the first-stage concrete (2) and lower than the top of the second-stage concrete (3).

4. The construction method for the underwater back cover of the open caisson according to claim 1, wherein: the water stop valve (5) is positioned in the secondary concrete (3).

Technical Field

The invention relates to a construction method for underwater bottom sealing of an open caisson, and belongs to the technical field of open caisson bottom sealing.

Background

The open caisson is a construction process for gradually sinking to a preset design elevation through continuously excavating soil from the interior under the enclosure of a well wall by self weight and then sealing the bottom, and has the advantages of more stable and reliable technology, less soil excavation amount, less influence on adjacent buildings, deeper foundation embedment of the open caisson, good stability, capability of supporting larger load and the like, thereby being widely applied to construction enclosure devices of foundation pits of large-scale piers, sewage pump stations, large-scale equipment foundations, civil air defense shelters, shield assembly wells, underground driveways and station hydraulic foundations.

At present, a dry bottom sealing and an underwater bottom sealing construction method are generally adopted for the underwater bottom sealing of the open caisson, wherein the underwater bottom sealing needs to adopt special concrete, construction is carried out completely according to a strict construction sequence and construction method, in addition, the problems that underwater construction workers cannot master the underwater condition and the like exist, the bottom sealing pouring quality is poor, the phenomena of bottom hole water seepage and water leakage occur subsequently, and the normal use of the subsequent open caisson is influenced.

In the prior art, as a construction system and a construction method of a dry bottom sealing of a filtering pumping open caisson disclosed in the Chinese patent with the publication number of 112922003, the method has the advantages of reducing the underwater construction difficulty of the bottom sealing of the open caisson and the like, underwater concrete is required to be poured after precipitation is completed, and underwater maintenance is adopted, but the construction cost is high and the precipitation significance is not great, and the construction difficulty is reduced and the pouring quality is improved by adopting impervious concrete for waterless operation; as disclosed in chinese patent publication No. 205954651, the structure reduces the difficulty and cost of underwater construction for bottom sealing of open caisson, ensures the quality of construction, is simple and easy to operate, but is only suitable for annular open caisson, and is easy to cause secondary sinking of open caisson due to replacement of gravel permeable layer and pouring of first layer of bottom sealing concrete at the bottom of open caisson slope, which affects the quality of construction and safety of construction.

Disclosure of Invention

In order to solve the technical problems, the invention provides a construction method for the underwater bottom sealing of the open caisson, which solves the problems that the pouring quality cannot be controlled in the process of the underwater bottom sealing of the open caisson and the like, and ensures the normal use function in the later stage of the engineering.

The invention is realized by the following technical scheme.

The invention provides a construction method for an underwater bottom sealing of an open caisson, which comprises the following steps:

shaft bottom replacement: cleaning the bottom of the open caisson, and then paving a permeable gravel layer;

burying and embedding a drain pipe: embedding pre-buried drain pipes in the permeable gravel layer, and pouring the drain pipes into the first-stage concrete and the second-stage concrete after precipitation is finished;

installing precipitation: connecting an external water pump to the top of the pre-buried drain pipe, and installing a water stop valve in the pre-buried drain pipe;

and after the permeable gravel layer is laid, starting a water suction pump, carrying out precipitation treatment on the bottom of the open caisson, pouring first-stage concrete, and when the strength of the first-stage concrete reaches more than 80%, closing the water suction pump and a water stop valve, and pouring second-stage concrete.

In the first step, a high-pressure water gun is used for cleaning sludge at the bottom of the open caisson, an air suction dredge is used for discharging slurry, then a permeable gravel layer is uniformly paved, and stone bricks are arranged at the blade feet of the open caisson.

The top of the pre-buried drain pipe is higher than the top of the first-stage concrete and lower than the top of the second-stage concrete.

The water stop valve is positioned in the second-stage concrete.

The invention has the beneficial effects that: the pre-buried drainage pipeline is utilized to firstly carry out precipitation treatment on the shaft bottom and then pour the first-stage concrete, the precipitation pipeline is plugged after the concrete strength meets the requirement, then the second-stage concrete pouring is carried out to the appointed elevation, and the bottom sealing is carried out on the open caisson, so that the concrete standard can be reduced, the special underwater concrete is not needed during the bottom sealing, only the concrete meets the anti-permeability requirement, secondly, the shaft bottom after precipitation is convenient to construct, the construction quality is easy to grasp, and the occurrence of the subsequent shaft bottom water leakage event is prevented.

Drawings

FIG. 1 is a cross-sectional view of the present invention;

in the figure: 1-permeable gravel layer, 2-first stage concrete, 3-second stage concrete, 4-embedded drain pipe, 5-water stop valve, 6-open caisson, 7-stone brick and 8-underground water surface line.

Detailed Description

The technical solution of the present invention is further described below, but the scope of the claimed invention is not limited to the described.

A construction method for underwater bottom sealing of an open caisson is suitable for underwater bottom sealing construction of the open caisson in any shape, and comprises the following steps:

shaft bottom replacement: cleaning the bottom of the open caisson, and then paving a permeable gravel layer 1;

burying and embedding a drain pipe 4: embedding a pre-buried drain pipe 4 in the permeable gravel layer 1, and pouring the drain pipe into the first-stage concrete 2 and the second-stage concrete 3 after precipitation is finished;

installing precipitation: the top of the pre-buried drain pipe (4) is connected with an external water pump, and a water stop valve (5) is arranged in the pre-buried drain pipe (4);

after the permeable gravel layer 1 is laid, the water suction pump is started, precipitation treatment is carried out on the bottom of the open caisson, the first-stage concrete 2 is poured, when the strength of the first-stage concrete 2 reaches more than 80%, the water suction pump and the water stop valve 5 are closed, and the second-stage concrete 3 is poured.

In the first step, a high-pressure water gun is used for cleaning sludge at the bottom of the open caisson, an air suction dredge is used for discharging slurry, then a permeable gravel layer 1 is uniformly paved, and stone bricks 7 are arranged at the blade feet of the open caisson.

The top of the pre-buried drain pipe 4 is higher than the top of the first-stage concrete 2 and lower than the top of the second-stage concrete 3.

The water stop valve 5 is positioned in the second-stage concrete 3.

Preferably, the bottom of the open caisson is subjected to precipitation treatment by the aid of the pre-buried drain pipes 4, pouring difficulty of the first-stage concrete 2 is reduced, the pre-buried drain pipes 4 are plugged after strength of the first-stage concrete 2 meets requirements, and then the second-stage concrete 3 is poured to meet design requirements, so that construction quality can be easily mastered, engineering problems are reduced, and normal functions of subsequent use of engineering are guaranteed.

Preferably, after the permeable gravel layer 1 is laid, the water suction pump is connected to the top of the pre-buried drain pipe 4 to perform precipitation treatment on the bottom of the open caisson, the number and the diameter of the pre-buried drain pipes 4 can be determined according to the size of the open caisson and drainage equipment, and the water can be lowered to a position below the designated elevation in the actual construction process through the pre-buried drain pipes 4.

Preferably, the first-stage concrete 1 is poured when the water level at the bottom of the open caisson is reduced to be below a specified height, the pouring thickness is required to meet the requirements of anti-floating and anti-seepage, and when the strength of the first-stage concrete 1 reaches more than 80%, the water stop valves 5 on the water suction pump and the pre-buried drain pipe 4 can be closed to prevent underground water from flowing out through the drain pipe, and then the second-stage concrete 3 is poured.

Preferably, the water stop valve 5 is used for preventing the water from gushing out when the second-stage concrete 3 is poured after precipitation is finished, the water stop valve 5 is opened in the precipitation process, and the water stop valve 5 is closed after precipitation is finished.

Further, the water stop valve 5 is poured into the second-stage concrete 3 in the pouring process, so that the normal use function of the subsequent engineering is not influenced.

Examples

As described above, after the open caisson 6 sinks to the right position in the construction process, the professional personnel uses the high-pressure water gun or other related professional equipment to remove silt and soft soil at the bottom of the well, and it should be noted that in the clear process, if the foundation at the edge of the open caisson is found to be unstable, the protection of the stone bricks 7 should be added, the size of the stone bricks 7 should not be too large, and the protection is carried out while excavation, so that the open caisson is prevented from sinking again; after the sludge is removed, laying the permeable gravel layer 1, wherein the laying thickness is determined according to related projects and geological conditions; in the process of laying the permeable gravel layer 1, pre-buried drain pipes 4 need to be buried in advance, and the tops of the pre-buried drain pipes 4 are higher than the top surface of the first-stage concrete 2 and lower than the top surface of the second-stage concrete 3; the pre-buried drain pipe 4 is provided with a water stop valve 5 within the thickness range of the second-stage concrete 3, and the top of the pre-buried drain pipe is connected with a water pump; the number and diameter of the pre-buried drain pipes 4 can be determined according to the size of the open caisson and drainage equipment, and the water level can be lowered to be lower than the designated height in the actual construction process through the pre-buried drain pipes 4, as shown in fig. 1.

The permeable gravel layer 1 is mainly used for replacing and filling a bottom mud layer, before bottom sealing construction of the open caisson, a professional needs to be sent into the well to clean the bottom mud by a high-pressure water gun, slurry is discharged by an air suction dredge at the same time, then the permeable gravel layer 1 is uniformly thrown, attention needs to be paid at the position, when the bottom is cleaned, the protection of soil bodies on the inclined plane of the edge foot of the open caisson is avoided, the open caisson is prevented from sinking again, if weak soil on the edge foot of the bottom is required to be excavated, timely protection needs to be carried out by adding stone bricks 7 while excavating, the safety problem caused by sinking of the open caisson is prevented, after the completion of sludge cleaning, subsequent permeable gravel layers 1 are laid, and the laying thickness is determined according to related projects and geological conditions.

The pre-buried drain pipe 4 is arranged in the permeable gravel layer 1, the top of the pre-buried drain pipe is higher than the top of the first-stage concrete 2 and lower than the top of the second-stage concrete 3, the water stop valve 5 is arranged in the range of the second-stage concrete 3, the pre-buried drain pipe 4 is used for precipitation treatment before the first-stage concrete 2 is poured, the first-stage concrete 2 is poured when the water level is reduced to a specified height, and the water stop valve 5 is closed and the second-stage concrete 3 is poured when the concrete strength reaches more than 80%.

To sum up, after the gravel layer 1 that permeates water is laid, open the suction pump, carry out precipitation treatment to the open caisson bottom, carry out the pouring of first stage concrete 2 after the water level drops to certain elevation, pour thickness and should satisfy anti superficial requirement, when first stage concrete intensity reaches more than 80%, can close the stagnant water valve 5 on precipitation equipment and the drain pipe, prevent that groundwater from gushing out through the drain pipe, then pour second stage concrete 3 to appointed elevation can.