CN111827297A - System and method for dewatering and excavation of sand egg stratum foundation pit - Google Patents

Abstract

The invention discloses a system and method for dewatering and excavating a foundation pit in a sand egg stratum. The system includes a foundation pit support component, and the foundation pit support component includes a surrounding plate, and the surrounding plate is hollow. a plate-like structure; the enclosure plate includes an outer plate for connecting with the foundation pit and an inner plate close to the center of the foundation pit, the outer plate is provided with a plurality of communication holes penetrating the inner and outer sides of the outer plate; the inner plate The plate is provided with a water outlet penetrating the inner and outer sides of the inner plate, and the fluid conduction capacity of the water outlet is adjustable; it also includes a water groove fixed on the inner plate, and the outlet end of the water outlet is located in the water groove. The method is based on the system. By adopting the system and method provided by this scheme, the excavation of the foundation pit and the construction in the foundation pit are facilitated, and the safety control of the drainage of the foundation pit is facilitated at the same time.

Description

System and method for dewatering and excavation of sand egg stratum foundation pit

technical field

The invention relates to the technical field of foundation pit construction, in particular to a system and method for dewatering and excavation construction of a sand egg stratum foundation pit.

Background technique

The foundation pit generally refers to the soil pit excavated at the base design position of the building according to the base elevation of the building and the size of the base plane. For foundation pit construction, the foundation pit support system is used as a temporary structure and a safety protection structure to prevent collapse during the construction of the foundation pit. At the same time, during the excavation and construction of the foundation pit, the problem of precipitation of the foundation pit needs to be considered.

Sand pebble geology is generally loose and water-rich. In the construction of foundation pits with water-rich sand and pebble strata close to important buildings, special attention should be paid to the impact of stratum precipitation on the surrounding environment. Therefore, in the existing construction, for the deep foundation pit in the sand egg stratum (excavation depth is more than 5 meters (including 5 meters), or the depth is not more than 5 meters, but the geological conditions and surrounding environment and underground pipelines are particularly complex foundation pit engineering. ) There are a series of problems in the construction process, such as difficult construction and great impact on the surrounding environment.

It is of great significance for building construction to carry out research on the optimization of precipitation and risk control for deep foundation pits in water-rich sand egg strata.

SUMMARY OF THE INVENTION

In view of the above-mentioned technical problems of great significance to the construction of the construction of the deep foundation pit dewatering optimization and risk control in the water-rich sand egg stratum, the present invention provides a system for the foundation pit dewatering and excavation construction in the sand egg stratum The system and method provided by this scheme are used to facilitate the excavation of the foundation pit and the construction in the foundation pit, and at the same time, it is convenient to realize the safety control of the drainage of the foundation pit.

The system and method for foundation pit dewatering and excavation construction in sand egg stratum provided by the present invention solve the problem through the following technical points. The system for sand egg stratum foundation pit dewatering and excavation construction includes foundation pit support components, The foundation pit support assembly includes a shroud, and the shroud is a hollow plate-like structure;

The enclosure plate includes an outer plate for connecting with the foundation pit and an inner plate close to the center of the foundation pit, and the outer plate is provided with a plurality of communication holes penetrating the inner and outer sides of the outer plate;

The inner side plate is provided with a drainage port penetrating the inner side and the outer side of the inner side panel, and the fluid conduction capacity of the drainage port is adjustable;

It also includes a water tank fixed on the inner side panel, and the outlet end of the water outlet is located in the water tank.

This scheme is aimed at the problems of difficult construction and easy to have a great impact on the surrounding environment during the construction of the foundation pit in the sand egg stratum, especially in the construction of the deep foundation pit. The characteristic of being extremely prone to collapse provides a technical solution that is beneficial to the optimization of precipitation and risk control of foundation pits in sand egg strata.

In the specific application of this scheme, the hoarding plate can be spliced by multiple plates. For example, according to the internal design, for the scheme without filter screen, 6 flat plates can be used for welding. The scheme is set as one of the plates is bolted to the connecting plate, etc. The inner side plate of the enclosure plate is attached to the wall of the foundation pit, so that the enclosure plate can be used as the retaining wall of the foundation pit.

Specifically, it is arranged that the enclosure plate includes a communication hole arranged on the outer plate, a water outlet arranged on the inner plate, and a water tank arranged on the inner plate. Using the characteristics of well point precipitation to achieve precipitation, a realization scheme of using the coaming plate as the drainage of the side wall of the foundation pit is provided: the water seeping from the side wall of the foundation pit enters the interior of the coaming plate through the communication holes, and then converges to the In the water tank, the purpose of safe and convenient dewatering of the foundation pit can be achieved under the condition of providing support for the side wall of the foundation pit.

At the same time, in consideration of the looseness of the sand egg stratum itself, the fluid conduction capacity of the drainage outlet is set to be adjustable, aiming at the premise that the excavation and dewatering in the foundation pit can be realized according to the excavation needs of the foundation pit. In order to reduce the impact of the foundation pit construction on the groundwater level, reduce the possibility of excessive holes around the foundation pit caused by the foundation pit construction, and achieve safe precipitation or drainage.

Further technical solutions are:

As a specific solution for the adjustable fluid conduction capacity of the drain outlet, it is set as follows: the number of the drain outlet is multiple, and the blocking state of some or all of the drain outlet is adjustable. In this scheme, a plurality of drainage ports are used to form the water outlet flow adjustment of the coaming plate, and the specific adjustment method adopts the method of blocking part of the drainage ports. In the specific application, if the drainage of the foundation pit does not meet the safety requirements, the state of all the drainage outlets as above can be adopted.

In the specific implementation of this scheme, in order to realize the multi-gradient adjustable drainage flow of the coaming plate through the drainage outlet, it is preferable to set the number of drainage outlets as much as possible. Concentrated water diversion leads to excessively large local holes in the foundation pit and enlarges the influence of the excavation of the foundation pit on the bottom layer. It is preferable to adopt the method that the communicating holes are evenly distributed on the entire surface of the outer plate. The filter screen arranged in the hollow space of the enclosure plate, in the thickness direction of the enclosure plate, the filter screen divides the hollow space into an outer cavity and an inner cavity, and the outer cavity is a filter screen and an outer plate The cavity between, the inner cavity is the cavity between the filter screen and the inner plate;

It also includes a mud discharge port connected to the bottom side of the coaming plate, and the inlet end is connected with the inner cavity;

It also includes a water injection port connected to the enclosure, and the outlet end is connected to the inner cavity;

Both the mud discharge port and the water injection port are provided with cut-off devices for controlling their respective on-off states. In this solution, the filter screen is used as the filter element between the communication hole and the drain port to avoid blockage of the drain port due to the introduction of sand, mud, etc. into the enclosure in a short time due to the large number of communication holes; The mud discharge port and the water injection port are designed to realize: regularly or when necessary, inject cleaning water through the water injection port to clean the outer cavity, and then discharge from the mud discharge port; it is arranged to further include a cut-off device, which aims to realize The mud discharge port is cut off when it is not necessary, and the fluid is only concentrated in the water tank and pumped out by the general pump body; the positions of the above mud discharge port and water injection port are limited, and the purpose is to cover the entire filter screen with the above cleaning water as much as possible. The above cut-off device is not only designed to achieve the above purpose of limiting the flow, but also can be used as a temporary storage space for sand and mud entering the coaming plate through the outer cavity. The influence of precipitation flow on formation safety at this time.

As a technical solution to solve the blockage of the communication holes by introducing pressure gas into the hollow space of the enclosure under the condition of closing the drains and shutting off the cut-off device, it is set as follows: each drain is matched with a plug, It also includes a communication pipe connected to the enclosure plate, and the outlet end communicates with the hollow space.

As a technical solution to facilitate the cleaning and maintenance of the filter screen during installation and use: the connection between the filter screen and the enclosure plate is achieved in the following ways: the remaining four surfaces of the enclosure plate are the upper end surface, the lower end surface, the left end surface and the right end respectively. surface, any one of the remaining four surfaces is bolted to the hoarding;

Two chutes in a facing relationship are provided on the wall surface of the hollow space of the enclosure plate, and the filter screen is clamped in the hollow space through the chutes;

The starting end of the chute is opposite to the surface of the shroud that is bolted to. With this solution, the removal or installation of the filter screen can be completed by pulling and inserting operations after the bolts are disconnected from the surface of the enclosure.

In order to reduce the design of the structural strength or rigidity of the filter screen, so as to realize the lightweight design of the filter screen and facilitate the corresponding operation of the filter screen, the design is as follows: a support plate arranged in the inner cavity is also included, and the filter screen is used as the inner side. The surface of the cavity boundary is supported on the support plate.

As a technical solution to facilitate the confinement of the enclosure plate at the edge of the foundation pit, it is provided as follows: a support frame for supporting the enclosure plate is further included, the support frame includes a vertical pole and a plurality of horizontal bars arranged along the axis direction of the vertical pole. The horizontal bar is used as a support between the vertical bar and the inner side of the enclosure, and the length of the horizontal bar is adjustable.

As a specific solution that the length of the crossbar is adjustable and easy to adjust, the crossbar includes a threaded barrel and a threaded rod connected in series, the threaded barrel and the threaded rod are threadedly connected and coaxial, and the threaded barrel is connected to the vertical rod. , a backing plate is also provided between the end of the threaded rod and the inner side of the enclosure;

The backing plate includes: a first plate body that is a steel plate, a second plate body that is a plastic plate or a graphite plate, and a third plate body that is a steel plate, the first plate body is fixedly connected with the threaded rod, the second plate body is The plate body is clamped between the first plate body and the third plate body, and the outer side of the bottom plate body is in contact with the inner side of the enclosure plate. This solution has a simple structure, and the second plate body serves as a wear-reducing plate between the first plate body and the third plate body, so as to facilitate the relative rotation of the first plate body and the third plate body.

As a method of balancing the force on both sides of the pole, it is convenient to stabilize the position of the pole in the space, so that the support frame is a split structure, which is convenient for the position transfer and storage of the support frame, so that the position of the cross bar can be easily adjusted according to the specific support needs. The technical scheme is set as follows: it also includes a sleeve sleeved on the vertical rod and capable of sliding along the axis of the vertical rod, two cross bars are fixed on each sleeve, and the cross bars on each sleeve are opposite to The axis of the sleeve is line-symmetric;

Also included is a locking device for achieving positional locking of the sleeve on the axis of the crossbar. The locking device can use bolts threaded on the sleeve to complete the locking by means of top-tightening, or use a bolt arranged between the sleeve and the vertical rod.

This solution also discloses a method for dewatering and excavating a foundation pit in a sand egg stratum, the method is based on the system described in any one of the above, and the method is realized by the following steps:

S1. On the wall surface of the excavated foundation pit, set the steel mesh as the internal steel structure skeleton of the concrete wall;

S2. Arrange a plurality of grouting pipes on the outer wall of the steel mesh. The grouting pipes are arranged at intervals. The gap between the adjacent grouting pipes is used as the fluid flow channel between the inlet end of the communication hole and the steel mesh. The upper edge of the grouting pipe is A plurality of grouting holes are arranged on the axis, and the orifices of the grouting holes face the steel mesh;

S3. Complete the erection of the enclosure plate, and the outer wall of the outer plate is attached to the grouting pipe;

S4. During the excavation and construction of the foundation pit, the coaming plate is used as the retaining and drainage wall to realize the water gushing discharge from the side of the foundation pit, and the drainage flow control is realized by adjusting the fluid conduction capacity of the drainage outlet;

S5. After completing the excavation and construction of the foundation pit, use the grouting pipe to inject concrete or slurry into the steel mesh, and use the enclosure plate as a support template during the curing process of the concrete or slurry. The above method provides a technical solution involving drainage of the foundation pit and long-term support and setting of the foundation pit during the construction of the foundation pit: specifically, steps S1 to S3 are to complete the installation of basic equipment, and step S4 is to use the system To realize the dewatering of the foundation pit, step S5 is to form a long-term support as a long-term retaining wall and a water blocking layer. To form the above long-term support, the system and the provided method are used, which are different from the prior art. In the process of precipitation, the grouting pipe is used for the cavity near the outer plate of the coaming plate that is easily formed due to precipitation in the sand egg stratum. That is, the cavity can be filled with mortar to facilitate the stability of the formation around the foundation pit. At the same time, this solution provides a technical solution that not only realizes the dewatering of the foundation pit, but also realizes the multi-purpose of the system.

The present invention has the following beneficial effects:

In the system structure design provided by this solution, specifically, the enclosure board includes a communication hole provided on the outer side panel, a water outlet provided on the inner side panel, and a water tank provided on the inner side panel. , this scheme provides a realization scheme of using the coaming plate as the drainage of the side wall of the foundation pit for the characteristics of sand egg formation such as it is difficult to use the well point precipitation to achieve dewatering: the water seeping from the side wall of the foundation pit enters the coaming plate through the communicating holes The inside of the water tank is collected into the water tank through the drainage port, so as to achieve the purpose of safe and convenient dewatering of the foundation pit under the condition of providing support for the side wall of the foundation pit.

At the same time, in consideration of the looseness of the sand egg stratum itself, the fluid conduction capacity of the drainage outlet is set to be adjustable, aiming at the premise that the excavation and dewatering in the foundation pit can be realized according to the excavation needs of the foundation pit. In order to reduce the impact of the foundation pit construction on the groundwater level, reduce the possibility of excessive holes around the foundation pit caused by the foundation pit construction, and achieve safe precipitation or drainage.

In the method design provided by this scheme, steps S1 to S3 are to complete the installation of basic equipment, step S4 is to use the system to realize foundation pit dewatering, and step S5 is to form long-term support as a long-term retaining wall and water blocking layer. To form the above long-term support, the system and the provided method are used, which are different from the prior art. In the process of precipitation, the grouting pipe is used for the cavity near the outer plate of the coaming plate that is easily formed due to precipitation in the sand egg stratum. That is, the cavity can be filled with mortar to facilitate the stability of the formation around the foundation pit. At the same time, this solution provides a technical solution that not only realizes the dewatering of the foundation pit, but also realizes the multi-purpose of the system.

Description of drawings

1 is a side view of a specific embodiment of the system for dewatering and excavation of sand egg formation foundation pit according to the present invention;

FIG. 2 is a partial schematic diagram of a specific embodiment of the system for dewatering and excavation of sand egg formation foundation pit according to the present invention, and the schematic diagram is used to reflect the structural composition of the coaming plate part.

The reference signs in the figure are: 1, enclosure plate, 2, cross bar, 3, vertical rod, 4, threaded barrel, 5, threaded rod, 6, backing plate, 7, mud discharge port, 8, connecting pipe, 9, water injection port, 10, grouting pipe, 11, steel mesh, 12, water tank, 13, drain outlet, 14, plug, 15, connecting hole, 16, filter screen, 17, support plate.

Detailed ways

The present invention will be described in further detail below in conjunction with the examples, but the structure of the present invention is not limited to the following examples.

Example 1:

As shown in Figures 1 and 2, a system for dewatering and excavation of a foundation pit in a sand egg stratum includes a foundation pit support assembly, and the foundation pit support assembly includes a shroud 1, and the shroud 1 is hollow the plate-like structure;

The enclosure plate 1 includes an outer plate for connecting with the foundation pit and an inner plate close to the center of the foundation pit, and the outer plate is provided with a plurality of communication holes 15 penetrating the inner and outer sides of the outer plate;

The inner side panel is provided with a drain port 13 penetrating the inner side and the outer side of the inner side panel, and the fluid conduction capacity of the drain port 13 is adjustable;

It also includes a water tank 12 fixed on the inner side panel, and the outlet end of the water outlet 13 is located in the water tank 12 .

This scheme is aimed at the problems of difficult construction and easy to have a great impact on the surrounding environment during the construction of the foundation pit in the sand egg stratum, especially in the construction of the deep foundation pit. The characteristic of being extremely prone to collapse provides a technical solution that is beneficial to the optimization of precipitation and risk control of foundation pits in sand egg strata.

In the specific application of this scheme, the enclosure 1 can be made of multiple plates. For example, according to the internal design, for the scheme without the filter screen 16, six flat plates can be welded. 16. The maintenance plan is set as one of the plates is bolted to the connecting plate, etc. The inner side plate of the enclosure plate 1 is attached to the wall of the foundation pit, so that the enclosure plate 1 can be used as a retaining wall of the foundation pit.

Specifically, it is configured that the enclosure plate 1 includes a communication hole 15 arranged on the outer plate, a water outlet 13 arranged on the inner plate, and a water tank 12 arranged on the inner plate. If the egg stratum is not easy to use the well point precipitation to achieve precipitation, a realization scheme of using the coaming plate 1 as the drainage of the side wall of the foundation pit is provided: the water seeped from the side wall of the foundation pit enters the interior of the coaming plate 1 through the communication hole 15 , and then converge into the water tank 12 through the drainage port 13, so as to achieve the purpose of safe and convenient dewatering of the foundation pit under the condition of providing support for the side wall of the foundation pit.

At the same time, in consideration of the looseness of the sand egg stratum itself, the fluid conductivity of the drainage outlet 13 is set to be adjustable, aiming at the requirement of excavation and dewatering in the foundation pit, for example, according to the excavation needs of the foundation pit. Under the premise, the water body should be led out as little as possible through the drainage port 13, so as to reduce the influence of the foundation pit construction on the groundwater level, reduce the possibility that the foundation pit construction will cause excessively large holes around the foundation pit, and realize safe precipitation or drainage.

Example 2:

As shown in FIG. 1 and FIG. 2 , this embodiment is further limited on the basis of Embodiment 1: as a specific solution for the adjustable fluid conduction capacity of the drain port 13 , it is set as follows: the number of the drain ports 13 There are multiple, and the blocking state of some or all of the drainage ports 13 is adjustable. In this solution, a plurality of drainage ports 13 are used to form the water outlet flow adjustment of the enclosure plate 1 , and the specific adjustment method adopts the method of blocking some of the drainage ports 13 . In the specific application, if the drainage of the foundation pit does not meet the safety requirements, the state in which all the drainage ports 13 above are blocked can be adopted.

In the specific implementation of this solution, in order to realize the multi-gradient adjustable drainage flow of the enclosure 1 through the drain port 13, it is preferable to set the number of drain ports 13 as much as possible. Water capacity, to avoid the effect of excessively large local holes in the foundation pit caused by concentrated water diversion and expanding the influence of the excavation of the foundation pit on the bottom layer. , is set to: also include a filter screen 16 arranged in the hollow space of the enclosure 1, in the thickness direction of the enclosure 1, the filter screen 16 divides the hollow space into an outer cavity and an inner cavity, so The outer cavity is the cavity between the filter screen 16 and the outer plate, and the inner cavity is the cavity between the filter screen 16 and the inner plate;

It also includes a mud discharge port 7 connected to the bottom side of the enclosure plate 1, and the inlet end is connected with the inner cavity;

It also includes a water injection port 9 connected to the enclosure plate 1, and the outlet end is connected to the inner cavity;

Both the mud discharge port 7 and the water injection port 9 are provided with cut-off devices for controlling their respective on-off states. In this solution, the filter screen 16 is used as the filter element between the communication hole 15 and the drain port 13, so as to avoid the drain port 13 being blocked due to the introduction of sand, mud, etc. Blocking; set to include the mud discharge port 7 and the water injection port 9, aiming to achieve: periodically or when necessary, inject cleaning water through the water injection port 9 to clean the outer cavity, and then discharge from the mud discharge port 7; It is arranged to also include a cut-off device, aiming to realize the cut-off of the mud discharge port 7 under unnecessary circumstances, and the fluid is only concentrated in the water tank 12 and extracted by a general pump body; the positions of the above mud discharge port 7 and water injection port 9 are limited, and the purpose is Cover the entire filter surface of the filter screen 16 with the above cleaning water as much as possible; the setting of the above cut-off device is not only intended to achieve the above purpose of limiting the flow, but also can be used as a temporary storage space for sand and mud entering the enclosure 1 through the outer cavity , for example, using the sand and mud accumulated in the outer cavity at a certain time interval to judge the influence of the precipitation flow on the formation safety at this time.

As a technical solution for solving the blockage of the communication holes 15 by introducing pressure gas into the hollow space of the enclosure plate 1 under the condition of closing the drain ports 13 and shutting off the cut-off device, it is set as follows: the drain ports 13 are matched with each other. There is a plug 14, and also includes a communication pipe 8 connected to the enclosure plate 1, and the outlet end communicates with the hollow space.

As a technical solution to facilitate the cleaning and maintenance of the filter screen 16 during installation and use: the connection between the filter screen 16 and the enclosure plate 1 is achieved in the following manner: the remaining four surfaces of the enclosure plate 1 are the upper end surface, the lower end surface, the Any one of the left end face and the right end face and the remaining four faces is bolted to the enclosure plate 1;

On the wall surface of the hollow space of the enclosure plate 1, two chutes are arranged in a facing relationship, and the filter screen 16 is clamped in the hollow space through the chutes;

The starting end of the chute is facing the surface where the bolts are connected to the enclosure plate 1 . With this solution, after the bolts connected to the enclosure plate 1 are detached, the removal or installation of the filter screen 16 can be completed by pulling and inserting operations.

In order to reduce the design of the structural strength or rigidity of the filter screen 16, so as to realize the lightweight design of the filter screen 16 to facilitate the corresponding operation of the filter screen 16, the design is as follows: it also includes a support plate 17 arranged in the inner cavity, the The filter screen 16 is supported on the support plate 17 as the surface of the inner cavity boundary.

As a technical solution to facilitate the confinement of the enclosure plate 1 at the edge of the foundation pit, it is configured as follows: a support frame for supporting the enclosure plate 1 is further included, and the support frame includes a vertical rod 3 and is arranged along the axis direction of the vertical rod 3 There are a plurality of cross bars 2, the cross bars 2 are used as the support between the vertical bars 3 and the inner side of the enclosure plate 1, and the length of the cross bars 2 is adjustable.

As a specific solution in which the length of the cross bar 2 is adjustable and easy to adjust, the cross bar 2 includes a threaded cylinder 4 and a threaded rod 5 connected in series, and the threaded cylinder 4 and the threaded rod 5 are threadedly connected and coaxial. The threaded barrel 4 is connected with the vertical rod 3, and a backing plate 6 is also provided between the end of the threaded rod 5 and the inner side of the enclosure plate 1;

The backing plate 6 includes: a first plate body that is a steel plate, a second plate body that is a plastic plate or a graphite plate, and a third plate body that is a steel plate. The first plate body is fixedly connected to the threaded rod 5, and the The second plate body is sandwiched between the first plate body and the third plate body, and the outer side of the bottom plate body is in contact with the inner side of the enclosure plate 1 . This solution has a simple structure, and the second plate body serves as a wear-reducing plate between the first plate body and the third plate body, so as to facilitate the relative rotation of the first plate body and the third plate body.

As a way of balancing the force on both sides of the pole 3, it is convenient to stabilize the position of the pole 3 in space, so that the support frame is a split structure, which is convenient for the position transfer and storage of the support frame, so that the horizontal adjustment can be conveniently adjusted according to specific support needs. The technical solution for the position of the rod 2 is set as follows: it further includes a sleeve sleeved on the vertical rod 3 and capable of sliding along the axis of the vertical rod 3, and two transverse rods 2 are fixed on each sleeve, and each sleeve is The cross bars 2 are all line-symmetrical with respect to the axis of the sleeve;

It also includes locking means for locking the position of the sleeve on the axis of the cross bar 2 . The locking device can use bolts threaded on the sleeve to complete the locking by means of top-tightening, or use a bolt arranged between the sleeve and the vertical rod 3 .

Example 3:

This embodiment discloses a method for dewatering and excavating a foundation pit in a sand egg stratum. The method is based on the system provided in any one of the above embodiments, and the method is implemented by the following steps:

S1, set the reinforcement mesh 11 as the internal steel structure skeleton of the concrete wall on the wall surface of the excavated foundation pit;

S2. Arrange a plurality of grouting pipes 10 on the outer wall of the steel mesh 11, and the grouting pipes 10 are arranged at intervals. , a plurality of grouting holes are arranged on the grouting pipe 10 along the axis, and the orifices of the grouting holes face the steel mesh 11;

S3, the erection of the enclosure plate 1 is completed, and the outer wall of the outer plate is attached to the grouting pipe 10;

S4. During the excavation and construction of the foundation pit, the coaming plate 1 is used as the retaining and drainage wall to realize the water gushing discharge from the side of the foundation pit, and the drainage flow control is realized by adjusting the fluid conduction capacity of the drainage outlet 13;

S5. After the excavation and construction of the foundation pit is completed, use the grouting pipe 10 to inject concrete or slurry into the steel mesh 11, and use the enclosure plate 1 as a support template during the curing process of the concrete or slurry. The above method provides a technical solution involving drainage of the foundation pit and long-term support and setting of the foundation pit during the construction of the foundation pit: specifically, steps S1 to S3 are to complete the installation of basic equipment, and step S4 is to use the system To realize the dewatering of the foundation pit, step S5 is to form a long-term support as a long-term retaining wall and a water blocking layer. To form the above long-term support, the system and the method provided are different from the prior art, because in the process of precipitation, the grouting pipe is used for the cavity near the outer plate of the coaming plate 1 that is easily formed due to precipitation in the sand egg formation. 10. The cavity can be filled with mortar to facilitate the stability of the formation around the foundation pit. At the same time, this solution provides a technical solution that not only realizes the dewatering of the foundation pit, but also realizes the multi-purpose of the system.

The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be considered that the specific embodiments of the present invention are limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, other embodiments obtained without departing from the technical solutions of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. The system for sand-egg stratum foundation pit dewatering and excavation construction comprises a foundation pit supporting assembly, wherein the foundation pit supporting assembly comprises a coaming (1), and is characterized in that the coaming (1) is of a hollow plate-shaped structure;

the coaming (1) comprises an outer side plate connected with the foundation pit and an inner side plate close to the center of the foundation pit, wherein a plurality of communicating holes (15) penetrating through the inner side and the outer side of the outer side plate are formed in the outer side plate;

the inner side plate is provided with a water outlet (13) which penetrates through the inner side and the outer side of the inner side plate, and the fluid communication capacity of the water outlet (13) is adjustable;

the water tank (12) is fixed on the inner side plate, and the outlet end of the water outlet (13) is positioned in the water tank (12).

2. The system for sand-egg formation foundation pit dewatering and excavation construction according to claim 1, wherein the number of the water discharge openings (13) is multiple, and the blocking state of part or all of the water discharge openings (13) is adjustable.

3. The system for sand-egg stratum foundation pit dewatering and excavation construction according to claim 1, characterized by further comprising a filter screen (16) arranged in the hollow space of the enclosing plate (1), wherein the filter screen (16) divides the hollow space into an outer cavity and an inner cavity in the plate thickness direction of the enclosing plate (1), the outer cavity is a cavity between the filter screen (16) and the outer plate, and the inner cavity is a cavity between the filter screen (16) and the inner plate;

the mud discharging port (7) is connected to the bottom side of the enclosing plate (1), and the inlet end of the mud discharging port is connected with the inner cavity;

the water injection port (9) is connected to the enclosing plate (1), and the outlet end of the water injection port is connected with the inner side cavity;

the sludge discharge port (7) and the water injection port (9) are provided with cut-off devices for controlling the on-off states of the sludge discharge port and the water injection port respectively.

4. The system for sand-egg formation foundation pit dewatering and excavation construction according to claim 3, characterized in that each drainage opening (13) is matched with a plug (14), and further comprises a communicating pipe (8) connected to the enclosing plate (1) and having an outlet end communicated with the hollow space.

5. The system for sand-egg stratum foundation pit dewatering and excavation construction according to claim 3, characterized in that the connection of the filter screen (16) and the coaming (1) is realized by: the other four surfaces of the coaming (1) are respectively an upper end surface, a lower end surface, a left end surface and a right end surface, and any one of the other four surfaces is connected to the coaming (1) through a bolt;

two chutes which are opposite to each other are arranged on the wall surface of the hollow space of the enclosing plate (1), and the filter screen (16) is clamped in the hollow space through the chutes;

the starting end of the sliding groove is opposite to the surface of the enclosing plate (1) connected with the bolt.

6. A system for sand and gravel formation pit dewatering and excavation according to claim 5, further comprising a support plate (17) disposed within the inner cavity, the filter screen (16) being supported on the support plate (17) as a surface of the inner cavity boundary.

7. The system for sand-gravel stratum foundation pit dewatering and excavation construction according to claim 1, further comprising a support frame for supporting the enclosing plate (1), wherein the support frame comprises a vertical rod (3) and a plurality of cross rods (2) arranged along the axial direction of the vertical rod (3), the cross rods (2) serve as support members between the vertical rod (3) and the inner side of the enclosing plate (1), and the length of the cross rods (2) is adjustable.

8. The system for sand-gravel stratum foundation pit dewatering and excavation construction according to claim 7, wherein the cross rod (2) comprises a threaded cylinder (4) and a threaded rod (5) which are connected in series, the threaded cylinder (4) is in threaded connection and coaxial with the threaded rod (5), the threaded cylinder (4) is connected with the upright rod (3), and a base plate (6) is further arranged between the end of the threaded rod (5) and the inner side of the enclosing plate (1);

the pad (6) comprises: for the first plate body of steel sheet, for the second plate body of plastic slab or graphite plate, for the third plate body of steel sheet, first plate body and threaded rod (5) fixed connection, the centre gripping of second plate body is between first plate body and third plate body, the outside and bounding wall (1) inboard contact of bottom plate body.

9. The system for sand-egg stratum foundation pit dewatering and excavation construction as claimed in claim 7 or 8, further comprising sleeves which are sleeved on the vertical rods (3) and can slide along the axes of the vertical rods (3), wherein two cross rods (2) are fixed on each sleeve, and the cross rods (2) on each sleeve are in line symmetry with respect to the axes of the sleeves;

the locking device is used for realizing the position locking of the sleeve on the axis of the cross rod (2).

10. Method for foundation pit dewatering and excavation in sandy-pebbly ground, characterised in that it is based on a system according to any one of claims 1 to 9, and in that it is carried out by:

s1, arranging a reinforcing mesh (11) serving as a steel structure framework in the concrete wall body on the wall surface of the excavated foundation pit;

s2, arranging a plurality of grouting pipes (10) on the outer wall of the reinforcing mesh (11), wherein the grouting pipes (10) are arranged at intervals, the gap between every two adjacent grouting pipes (10) is used as a fluid circulation channel between the inlet end of the communication hole (15) and the reinforcing mesh (11), a plurality of grouting holes are arranged on each grouting pipe (10) along the axial line, and the openings of the grouting holes face the reinforcing mesh (11);

s3, erecting the coaming (1), wherein the outer wall of the outer side plate is attached to the grouting pipe (10);

s4, in the process of foundation pit excavation and construction, the side surface of the foundation pit is flushed and discharged by using the enclosing plate (1) as a soil-retaining drainage wall, and drainage flow control is realized by adjusting the fluid conduction capacity of the drainage outlet (13);

s5, after foundation pit excavation and construction are completed, concrete or slurry is injected into the reinforcing mesh (11) through the grouting pipe (10), and the coaming (1) is used as a supporting template in the concrete or slurry curing process.

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