CN113756347B - Supporting bearing platform construction auxiliary equipment and construction method - Google Patents

Abstract

The invention discloses a construction auxiliary device and a construction method for a supporting bearing platform, and the construction method specifically comprises the following steps: constructing a closed cofferdam, and sealing the closed cofferdam by utilizing the angle steel sheet piles; excavating a foundation pit, installing a first inner support when the position of the first-layer inner support is excavated to be below 50cm, and temporarily fixing the first inner support through a limiting block; continuously excavating, namely, when the position of the support in the second layer is excavated to be below 50cm, hanging a second inner support, temporarily fixing the second inner support through a limiting block when the second inner support reaches a limiting part on the first inner support, unlocking the first inner support, and fixing the first inner support when the first inner support reaches the position of the support in the second layer; repeating the steps, and installing the inner support according to the depth requirement; excavating a back cover, and constructing a bearing platform; the inner supports are removed step by step according to the construction progress, and the purpose of improving the bearing platform construction efficiency can be achieved through the construction method.

Description

Supporting bearing platform construction auxiliary equipment and construction method

Technical Field

The invention relates to the technical field of bridge construction, in particular to a supporting bearing platform construction auxiliary device and a construction method.

Background

In civil engineering foundation construction, such as bridge bearing platform construction, a steel sheet pile cofferdam is a common construction method at present. The steel sheet pile cofferdam is mainly used for preventing water and soil from entering the building position of a building, so that water is drained in the cofferdam, a foundation pit is excavated, and the building is carried out.

The process of building of carrying out the cofferdam is various, in order to guarantee the stability of cofferdam, in the position of cofferdam corner, often adopt the connection of the steel sheet pile of dysmorphism steel sheet pile realization handing-over position, in prior art, at the in-process of building of cofferdam, thereby often set up the stability of interior support assurance cofferdam in the cofferdam, adopt the supported mode of interior support, often need adopt the mode of temporary welding short shaped steel in the side of cofferdam, realize the location of interior support, but be directed against the construction process of cofferdam, often set up a plurality of interior supports, thereby the construction efficiency is influenced each other at the in-process of building to the event between a plurality of interior supports.

In view of this, the present application is specifically made.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides the support cushion cap construction auxiliary equipment, which can realize the quick construction of the cofferdam through the structure, and can ensure the stability of the structure while improving the construction efficiency; in a second aspect, the invention provides a construction method for a supporting bearing platform, and through the construction method, the purpose of improving the construction efficiency of the bearing platform can be achieved.

First aspect

The embodiment of the invention provides a rotating angle steel sheet pile,

the supporting and bearing platform construction auxiliary equipment comprises a closed cofferdam formed by a plurality of Larsen steel sheet piles in a surrounding mode, and the closed cofferdam further comprises corner steel sheet piles, wherein the corner steel sheet piles are arranged at the corner positions of the Larsen steel sheet piles and used for realizing the sealing of the Larsen steel sheet piles; the angle steel sheet pile comprises a first baffle and a second baffle; one end of the first baffle plate is connected with one end of the second baffle plate in an angle; connecting pieces used for being connected with the Larsen steel sheet piles are arranged at the other ends of the first baffle and the second baffle; and a reinforcing plate is further arranged in an included angle formed by the first baffle and the second baffle, one end of the reinforcing plate is fixedly connected with the first baffle, and the other end of the reinforcing plate is fixedly connected with the second baffle.

In the scheme, the supporting bearing platform construction auxiliary equipment comprises a closed cofferdam formed by a plurality of Larsen steel sheet piles in a surrounding mode, the Larsen steel sheet piles are connected through the angle steel sheet piles at the corner positions of the closed cofferdam to form the closed cofferdam, each angle steel sheet pile comprises a first baffle and a second baffle, one end of each first baffle and one end of each second baffle are arranged in an included angle mode, the other end of each first baffle is connected with the Larsen steel sheet piles, reinforcing plates are further arranged in the included angles of the first baffle and the second baffle, the two ends of each reinforcing plate are respectively connected with the first baffle and the second baffle, the structural strength of each angle steel sheet pile can be effectively guaranteed, compared with the prior art, in the building process of the closed cofferdam by using the structure related to achieve surrounding of the Larsen steel sheet piles rapidly through the structural design of the angle steel sheet piles, and accordingly construction efficiency is improved.

Further, still include the interior support, the interior support includes the frame that is enclosed by a plurality of shaped steel, the shape of frame with the shape looks adaptation of the cross section of closed cofferdam, the frame be used for with the inner wall of closed cofferdam is mutually supported, realizes the support of closed cofferdam, through the structural design of interior support, can effectually guarantee the stability of closed cofferdam to guarantee engineering construction's security.

Furthermore, the corner of frame is provided with the connecting plate, two adjacent shaped steel are connected respectively to the both ends of connecting plate, through the structural design of connecting plate, when avoiding the reinforcing plate is to the influence of closed cofferdam cross section, has guaranteed the stability of closed cofferdam.

Further, when the inner support is matched with the closed cofferdam, the connecting plate is parallel to the reinforcing plate.

Furthermore, the connecting plate is also provided with a limiting piece; be provided with on the reinforcing plate along the spacing portion that the depth direction of closing the cofferdam extends, the locating part with spacing portion mutually supports, realizes the frame is in the fixed of the relative position of closing the cofferdam, through the cooperation of locating part and spacing portion can realize the interim fixed of interior support, compare in the mode through welding outside support piece among the prior art, the interim fixed of support in realization that can be quick can effectually improve the efficiency of construction.

Further, the limiting member comprises a limiting block, the limiting block has a first state and a second state, and when the limiting block is in the first state, the inner support freely moves along the depth direction of the closed cofferdam; when the limiting block is in a second state, when the inner support moves towards the bottom of the closed cofferdam, the limiting block is matched with the limiting part to prevent the inner support from moving towards the bottom of the closed cofferdam; when the inner support moves towards the top of the closed cofferdam, the limiting block can move towards the top of the closed cofferdam through the limiting part.

Furthermore, the limiting block is connected with the connecting plate through an elastic piece, so that the change of the relative distance between one end of the limiting block, which is far away from the connecting plate, and the connecting plate is realized; the limiting part comprises a plurality of limiting bulges, each limiting bulge comprises a limiting surface and a guide surface, the guide surface is close to the bottom surface of the closed cofferdam relative to the limiting surface, the limiting surface is parallel to the bottom surface of the closed cofferdam, and the guide surface is inclined relative to the bottom surface of the closed cofferdam.

Furthermore, the limiting block is connected with the connecting plate through a first connecting plate and a second connecting plate, one end of the first connecting plate is vertically connected with the connecting plate, the other end of the first connecting plate is vertically connected with the second connecting plate, a first through hole is formed in the first connecting plate, a first adjusting rotary rod is arranged in the first through hole, and longitudinal umbrella teeth are arranged at the lower end of the first adjusting rotary rod; a second through hole is formed in the second connecting plate, a second adjusting rotary rod is arranged in the second through hole, transverse bevel teeth are arranged at one end of the second adjusting rotary rod, the longitudinal bevel teeth and the transverse bevel teeth are in meshing transmission connection, and the limiting block is located at the other end of the second adjusting rotary rod; the reinforcing plate is provided with strip holes, the strip holes extend along the depth direction of the closed cofferdam, and the limiting parts are arranged at intervals along the length direction of the strip holes; the width of the limiting part is larger than that of the strip hole, when the first adjusting rotary rod drives the limiting block to rotate, when the axis of the limiting block is parallel to the length direction of the strip hole, the limiting block can pass through the limiting part to realize that the inner support moves in the length direction of the closed cofferdam, and when the axis of the limiting block is perpendicular to the length direction of the strip hole, the limiting block is matched with the limiting part to realize the locking of the limiting block in the limiting part.

Further, the inner support is multiple.

Second aspect of the invention

The embodiment of the invention also provides a construction method of the supporting bearing platform, and based on the auxiliary equipment for supporting bearing platform construction, the construction method comprises the following steps:

s1: constructing a closed cofferdam, and utilizing the angle iron sheet piles to realize the closure of the closed cofferdam;

s2: excavating a foundation pit, installing a first inner support when the position of the first-layer inner support is excavated to be below 50cm, and temporarily fixing the first inner support through the limiting block;

s3: continuing excavation, namely, when the excavation is carried out to the position below 50cm of the mounting position of the support in the second layer, hanging the second inner support, temporarily fixing the second inner support through the limiting block when the second inner support reaches the upper limiting part of the first inner support, unlocking the first inner support, and fixing the first inner support when the first inner support reaches the mounting position of the support in the second layer;

s4: repeating the steps S2-S3, and installing a plurality of inner supports according to the depth requirement;

s5: excavating a back cover, and constructing a bearing platform;

s6: and removing the inner supports step by step according to the construction progress.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides a supporting cushion cap construction auxiliary device and a construction method, through the structural design aiming at the construction auxiliary device, the construction of a closed cofferdam can be quickly realized, and through the structural design of a limiting part and a limiting part, the supporting of inner supports in the cofferdam can be quickly realized, the stability of the cofferdam is effectively ensured, and through the use of a specific construction method, in the construction process of a supporting cushion cap, the technical problem that a plurality of inner supports are required to be designed for ensuring the stability of the cofferdam in the prior art, but the mutual influence among the inner supports is avoided, the efficiency of cofferdam construction is greatly reduced, and the improvement of the construction efficiency is realized while the stability is ensured.

Drawings

The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention.

Fig. 1 is a schematic structural diagram of a corner steel sheet pile provided in an embodiment of the present invention;

FIG. 2 is a schematic structural view of a closed cofferdam provided in an embodiment of the present invention;

fig. 3 is a schematic structural diagram of a position-limiting element according to an embodiment of the present invention;

fig. 4 is a schematic structural diagram of a limiting portion according to an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a limiting element according to another embodiment of the present invention;

FIG. 6 is a front view of a connection plate provided by an embodiment of the present invention;

FIG. 7 is a schematic illustration of the structure of an inner support according to an embodiment of the present invention;

FIG. 8 is a schematic illustration of an alternative inner support structure according to an embodiment of the present invention;

fig. 9 is a schematic step view of a supporting and bearing platform construction method provided in an embodiment of the present invention.

The reference numbers in the figures are in order:

100-angle steel sheet pile, 110-first baffle, 120-second baffle, 130-reinforcing plate, 131 a-limiting part, 200-Larsen steel sheet pile, 300-inner support, 310-outer frame, 311-connecting plate, 311 a-limiting part, 311 a-1-limiting block and 311 a-2-elastic part.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by a person of ordinary skill in the art without creative efforts based on the embodiments of the present invention belong to the protection scope of the present invention.

Examples

As shown in fig. 1-2, an embodiment of the present invention provides a supporting platform construction auxiliary device, including a closed cofferdam surrounded by a plurality of larsen steel sheet piles 200, where the closed cofferdam further includes corner steel sheet piles 100, and the corner steel sheet piles 100 are disposed at corners of the larsen steel sheet piles 200, and are used to implement the sealing of the larsen steel sheet piles 200; the angle iron sheet pile 100 comprises a first baffle 110 and a second baffle 120; one end of the first baffle 110 and one end of the second baffle 120 are connected in an angle; the other ends of the first baffle 110 and the second baffle 120 are provided with connecting pieces for connecting with the Larsen steel sheet pile 200; still be provided with reinforcing plate 130 in the contained angle that first baffle 110 and second baffle 120 formed, the one end of reinforcing plate 130 with first baffle 110 fixed connection, the other end of reinforcing plate 130 with second baffle 120 fixed connection.

Wherein, as should know of technical personnel in the field, the larsen steel sheet pile 200 comprises a plurality of larsen steel sheet steel plates, and the both sides of larsen steel sheet are provided with the connecting piece that is used for realizing the larsen steel sheet and connects respectively, the connecting piece of angle bar sheet pile 100 is used for being connected with the connecting piece of larsen steel sheet, realizes angle bar sheet pile 100 with the connection of larsen steel sheet.

The first baffle 110 and the second baffle 120 are connected at an angle, specifically, the angle may be an obtuse angle, a right angle or an acute angle, which is determined according to the actual situation of the construction site, but it should be noted that when the angle between the first baffle 110 and the second baffle 120 is a right angle, the stability of the connection of the first baffle 110 and the second baffle 120 through the reinforcing plate 130 is stronger, for example, when the underwater bearing platform is constructed, the impact force of the water flow on the closed cofferdam can be effectively dispersed, and the impact condition is more stable than the conditions of the right angle and the obtuse angle.

Specifically, the larsen steel plate is a long strip-shaped structure, the main purpose of the rotor steel plate pile 100 is to achieve connection of the larsen steel plate pile 200 at a corner position, and therefore, the rotor steel plate pile 100 should be adapted to the shape of the larsen steel plate and also be long, the reinforcing plate 130 is provided to ensure stability of the first baffle plate 110 and the second baffle plate 120, and therefore the reinforcing plate 130 should have the same length as the rotor steel plate pile 100.

In this embodiment, the construction auxiliary equipment for the supporting bearing platform includes a closed cofferdam formed by enclosing a plurality of Larsen steel sheet piles 200, the Larsen steel sheet piles 200 are connected through the angle steel sheet piles 100 at the corner positions of the closed cofferdam to form the closed cofferdam, each angle steel sheet pile 100 includes a first baffle 110 and a second baffle 120, one end of each of the first baffle 110 and the second baffle 120 is arranged at an included angle, the other end of each of the first baffle 110 and the second baffle 120 is used for being connected with the Larsen steel sheet pile 200, a reinforcing plate 130 is further arranged in the included angle of the first baffle 110 and the second baffle 120, and two ends of the reinforcing plate 130 are respectively connected with the first baffle 110 and the second baffle 120, so that the structural strength of the angle steel sheet piles 100 can be effectively ensured.

In some embodiments, the inner support 300 is further included, the inner support 300 includes an outer frame 310 formed by enclosing a plurality of section steels, the shape of the outer frame 310 is adapted to the shape of the cross section of the closed cofferdam, the outer frame 310 is used for being matched with the inner wall of the closed cofferdam to realize the support of the closed cofferdam, and through the structural design of the inner support 300, the stability of the closed cofferdam can be effectively ensured, so that the safety of engineering construction is ensured.

Further, the inner support 300 is plural.

As shown in fig. 7-8, as a person skilled in the art should know, in order to ensure the stability of the inner support 300, different support members should be further disposed in the outer frame 310 to ensure the stability of the outer frame 310, and for different stability requirements, different forms of braces may be disposed to meet the support requirements.

The shape of the outer frame 310 is adapted to the shape of the cross section of the closed cofferdam, and it should be noted that the closed cofferdam is surrounded by the larsen steel sheet piles 200, so the outer frame 310 should contact with the inner surface of the closed cofferdam to support the closed cofferdam.

In some embodiments, a connecting plate 311 is disposed at a corner of the outer frame 310, two ends of the connecting plate 311 are respectively connected to two adjacent section steels, and through the structural design of the connecting plate 311, the stability of the closed cofferdam is ensured while the influence of the reinforcing plate on the cross section of the closed cofferdam is avoided.

In the closed cofferdam, the corner positions are connected by the angle iron sheet piles 100, the angle iron sheet piles 100 are provided with the reinforcing plates 130 for enhancing the stability of the angle iron sheet piles 100, and the connecting sections of the reinforcing plates 130 are connected with the first baffle 110 and the second baffle 120, so that the reinforcing plates 130 are inevitably present at the corner positions of the cross section of the closed cofferdam to influence the shape of the cross section, and in order to avoid the interference between the corner positions of the inner supports 300 and the reinforcing plates 130, the end parts of the profile steels at the two sides of the corner positions of the outer frame 310 form one side of the inner surface of the closed cofferdam, and contact one side of the outer surface at a certain interval.

In some embodiments, the web 311 is parallel to the reinforcement panel 130 when the inner support 300 is interfitted with the closed cofferdam.

As shown in fig. 3-6, in some embodiments, the connecting plate 311 is further provided with a limiting member 311a; the reinforcing plate 130 is provided with a limiting part 131a extending along the depth direction of the closed cofferdam, the limiting part 311a and the limiting part 131a are mutually matched to fix the outer frame 310 at the relative position of the closed cofferdam, and the temporary fixation of the inner support 300 can be realized through the matching of the limiting part 311a and the limiting part 131a, so that compared with the mode of welding an external support member in the prior art, the temporary fixation of the inner support 300 can be quickly realized, and the construction efficiency can be effectively improved.

In some embodiments, the limiting member 311a includes a limiting block 311a-1, the limiting block 311a-1 has a first state and a second state, when the limiting block 311a-1 is in the first state, the inner support 300 is free to move along the depth direction of the closed cofferdam; when the limiting block 311a-1 is in the second state, when the inner support 300 moves towards the bottom of the closed cofferdam, the limiting block 311a-1 and the limiting part 131a are matched with each other to prevent the inner support 300 from moving towards the bottom of the closed cofferdam; when the inner support 300 moves towards the top of the closed cofferdam, the limiting block 311a-1 can move towards the top of the closed cofferdam through the limiting part 131 a.

As a specific embodiment of the limiting member 311a and the limiting portion 131a, the limiting member 311a-1 is connected to the connecting plate 311 by an elastic member 311a-2, so as to change a relative distance between an end of the limiting member 311a-1 away from the connecting plate 311 and the connecting plate 311; the limiting part 131a comprises a plurality of limiting protrusions, each limiting protrusion comprises a limiting surface and a guide surface, the guide surface is close to the bottom surface of the closed cofferdam relative to the limiting surface, the limiting surface is parallel to the bottom surface of the closed cofferdam, and the guide surface is inclined relative to the bottom surface of the closed cofferdam.

As another specific embodiment of the limiting member 311a and the limiting portion 131a, the limiting member 311a-1 is connected to the connecting plate 311 through a first connecting plate 311 and a second connecting plate 311, one end of the first connecting plate 311 is vertically connected to the connecting plate 311, the other end of the first connecting plate 311 is vertically connected to the second connecting plate 311, the first connecting plate 311 is provided with a first through hole, a first adjusting rotary rod is arranged in the first through hole, and a longitudinal bevel gear is arranged at the lower end of the first adjusting rotary rod; a second through hole is formed in the second connecting plate 311, a second adjusting rotary rod is arranged in the second through hole, transverse bevel teeth are arranged at one end of the second adjusting rotary rod, the longitudinal bevel teeth and the transverse bevel teeth are in meshing transmission connection, and the limiting block 311a-1 is located at the other end of the second adjusting rotary rod; the reinforcing plate 130 is provided with strip holes, the strip holes extend along the depth direction of the closed cofferdam, and the limiting parts 131a are arranged at intervals along the length direction of the strip holes; the width of the limiting part 131a is greater than the width of the elongated hole, when the first adjusting lever drives the limiting block 311a-1 to rotate, when the axis of the limiting block 311a-1 is parallel to the length direction of the elongated hole, the limiting block 311a-1 can realize that the inner support 300 moves in the length direction of the closed cofferdam through the limiting part 131a, and when the axis of the limiting block 311a-1 is perpendicular to the length direction of the elongated hole, the limiting block 311a-1 and the limiting part 131a cooperate with each other to realize that the limiting block 311a-1 is locked in the limiting part 131 a.

It should be noted that the purpose of the reinforcing plate 130 is to ensure the stability of the first baffle 110 and the second baffle 120, and if the elongated hole is a through hole, the effect of the reinforcing plate 130 is influenced to some extent, so based on this, one end of the elongated hole, i.e. the end far away from the connecting plate 311, is a closed structure, thereby ensuring the stability of the reinforcing plate.

It should be noted that, in the present embodiment, through the structural design of the limiting member 311a and the limiting portion 131a, the main purpose is to achieve the temporary fixing of the inner support 300, compared with the method of directly adopting a welding support member in the prior art, the state of the limiting member 311a can be changed in a targeted manner, so as to achieve the temporary fixing of the inner support 300, which has the advantage of convenient installation, and in order to further ensure the inner support 300, in order to ensure the temporary fixing of the inner support 300, it may be considered to adopt a reinforcing manner to ensure stability after the temporary fixing of the inner support 300 is completed.

As shown in fig. 9, an embodiment of the present invention further provides a construction method for a supporting platform, and based on the above-mentioned auxiliary device for supporting platform construction, the method includes the following steps:

s1: constructing a closed cofferdam, and utilizing the angle iron sheet piles 100 to realize the closure of the closed cofferdam;

s2: excavating a foundation pit, installing a first inner support 300 when the position of the first-layer inner support 300 is excavated to be below 50cm, and temporarily fixing the first inner support 300 through the limiting block 311 a-1;

s3: continuing excavation, namely, when the excavation is carried out to the mounting position of the support 300 in the second layer by less than 50cm, hanging the second inner support 300, when the second inner support 300 reaches a limiting part 131a on the first inner support 300, realizing temporary fixing of the second inner support 300 through the limiting block 311a-1, unlocking the first inner support 300, and when the first inner support 300 reaches the mounting position of the support 300 in the second layer, fixing the first inner support 300;

s4: repeating the steps S2-S3, and installing a plurality of inner supports 300 according to the depth requirement;

s5: excavating a back cover, and constructing a bearing platform;

s6: and removing the inner support 300 step by step according to the construction progress.

The above embodiments are preferred embodiments of the present invention, and those skilled in the art can make variations and modifications to the above embodiments, so that the present invention is not limited to the above embodiments, and any obvious improvements, substitutions or modifications based on the present invention by those skilled in the art are within the protection scope of the present invention.

Claims (4)

1. A supporting bearing platform construction auxiliary device comprises a closed cofferdam formed by a plurality of Larsen steel sheet piles (200) in a surrounding way, and is characterized in that,

the closed cofferdam further comprises corner steel sheet piles (100), wherein the corner steel sheet piles (100) are arranged at the corner positions of the Larsen steel sheet piles (200) and used for realizing the closing of the Larsen steel sheet piles (200);

the angle iron sheet pile comprises a first baffle plate (110) and a second baffle plate (120);

one end of the first baffle (110) and one end of the second baffle (120) are connected in an angle;

the other ends of the first baffle plate (110) and the second baffle plate (120) are respectively provided with a connecting piece for connecting with a Larsen steel sheet pile;

a reinforcing plate (130) is further arranged in an included angle formed by the first baffle plate (110) and the second baffle plate (120), one end of the reinforcing plate (130) is fixedly connected with the first baffle plate (110), and the other end of the reinforcing plate (130) is fixedly connected with the second baffle plate (120);

the inner support (300) is further included, the inner support (300) comprises an outer frame (310) formed by a plurality of section steels in a surrounding mode, the shape of the outer frame (310) is matched with the shape of the cross section of the closed cofferdam, and the outer frame (310) is used for being matched with the inner wall of the closed cofferdam to realize the support of the closed cofferdam;

a connecting plate (311) is arranged at a corner of the outer frame (310), and two ends of the connecting plate (311) are respectively connected with two adjacent section steels;

-said connecting plates (311) are parallel to said reinforcing plates (130) when said inner support (300) is interfitted with said closed cofferdam;

the connecting plate (311) is also provided with a limiting piece (311 a); a limiting part (131 a) extending along the depth direction of the closed cofferdam is arranged on the reinforcing plate (130), and the limiting part (311 a) is matched with the limiting part (131 a) to realize the fixation of the outer frame (310) at the relative position of the closed cofferdam;

the limiting part (311 a) comprises a limiting block (311 a-1), the limiting block (311 a-1) has a first state and a second state, and when the limiting block (311 a-1) is in the first state, the inner support (300) freely moves along the depth direction of the closed cofferdam; when the limiting block (311 a-1) is in the second state, when the inner support (300) moves towards the bottom of the closed cofferdam, the limiting block (311 a-1) is matched with the limiting part (131 a) to prevent the inner support (300) from moving towards the bottom of the closed cofferdam; when the inner support (300) moves towards the top of the closed cofferdam, the limiting block (311 a-1) can move towards the top of the closed cofferdam through the limiting part (131 a);

the limiting block (311 a-1) is connected with the connecting plate (311) through an elastic piece (311 a-2), so that the relative distance of one end, away from the connecting plate (311), of the limiting block (311 a-1) relative to the connecting plate (311) is changed; the limiting part (131 a) comprises a plurality of limiting bulges, each limiting bulge comprises a limiting surface and a guide surface, the guide surface is close to the bottom surface of the closed cofferdam relative to the limiting surface, the limiting surfaces are arranged in parallel relative to the bottom surface of the closed cofferdam, and the guide surfaces are obliquely arranged relative to the bottom surface of the closed cofferdam.

2. The supporting cushion cap construction auxiliary device of claim 1, wherein the limiting block (311 a-1) is connected with the connecting plate (311) through a first connecting plate and a second connecting plate, one end of the first connecting plate is vertically connected with the connecting plate (311), the other end of the first connecting plate is vertically connected with the second connecting plate, the first connecting plate is provided with a first through hole, a first adjusting rotary rod is arranged in the first through hole, and the lower end of the first adjusting rotary rod is provided with longitudinal umbrella teeth; a second through hole is formed in the second connecting plate, a second adjusting rotary rod is arranged in the second through hole, transverse umbrella teeth are arranged at one end of the second adjusting rotary rod, the longitudinal umbrella teeth and the transverse umbrella teeth are in meshing transmission connection, and the limiting block (311 a-1) is located at the other end of the second adjusting rotary rod; the reinforcing plate (130) is provided with strip holes, the strip holes extend along the depth direction of the closed cofferdam, and the limiting parts (131 a) are arranged at intervals along the length direction of the strip holes; the width of the limiting part (131 a) is greater than that of the elongated hole, when the first adjusting rotary rod drives the limiting block (311 a-1) to rotate, when the axis of the limiting block (311 a-1) is parallel to the length direction of the elongated hole, the limiting block (311 a-1) can realize that the inner support (300) moves in the length direction of the closed cofferdam through the limiting part, and when the axis of the limiting block (311 a-1) is perpendicular to the length direction of the elongated hole, the limiting block (311 a-1) is matched with the limiting part, so that the limiting block (311 a-1) is locked in the limiting part.

3. A support platform construction aid according to claim 1, wherein the inner support is plural.

4. A construction method of a supporting cap, which is based on any one of claims 1 to 3, and comprises the following steps:

s1: constructing a closed cofferdam, and utilizing the angle iron sheet piles to realize the closure of the closed cofferdam;

s2: excavating a foundation pit, installing a first inner support when the position of the first-layer inner support is excavated to be below 50cm, and temporarily fixing the first inner support through the limiting block (311 a-1);

s3: continuing excavation, namely, when the excavation is carried out to the position below 50cm of the mounting position of the support in the second layer, hanging the second inner support, when the second inner support reaches the upper limit part of the first inner support, realizing temporary fixing of the second inner support through the limit block (311 a-1), unlocking the first inner support, and when the first inner support reaches the mounting position of the support in the second layer, fixing the first inner support;

s4: repeating the steps S2-S3, and installing a plurality of inner supports according to the depth requirement;

s5: excavating a back cover, and constructing a bearing platform;

s6: and removing the inner supports step by step according to the construction progress.

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