CN112982424A - Open caisson construction method - Google Patents

Abstract

The invention discloses a sunk well construction method which is characterized by comprising the following steps: s100, installing a safety guardrail, finishing construction enclosure, and excavating a foundation pit slope-laying platform; s110, mounting a prestressed high-strength concrete pipe pile; s120, installing a cement-soil stirring bottom sealing pile and a cement-soil stirring pile; s130, in-situ casting a first section of open caisson section; s140, sinking the first section of open caisson; s150, casting a second open caisson section on the first open caisson section in a cast-in-place mode; s160, sinking the second section of open caisson in a segmented manner; s170, constructing open caisson underwater bottom sealing concrete, pouring an underground passage bottom plate, and backfilling foundation pit fertilizer groove plain concrete; s180, after the second steel pipe support is removed, construction of the side wall and the top plate of the underground passage is completed; s190, when the rigidity of a top plate and the rigidity of a side wall of the structure reach a preset value, backfilling a gap between the structure and the wall of the open caisson, and removing the first concrete support; s200, backfilling a site above a top plate; by applying the open caisson construction method, the open caisson can be safely, smoothly and accurately sunk to a preset position.

Description

Open caisson construction method

Technical Field

The invention relates to the field of foundation pit supporting construction, in particular to a sunk well construction method.

Background

A foundation pit refers to a soil pit excavated at a foundation design position according to the substrate elevation and the foundation plane size; in urban construction engineering, a foundation pit is mainly used for construction of underground buildings such as building basements, underground passages, underground pipe galleries, subway stations, bridge abutments and the like, and is generally divided into two types, namely no support and support; because the soil quality of the existing foundation pit construction site is unstable, the influence of underground water is often accompanied; therefore, supporting excavation is increasingly used.

In deep silt areas such as coastal areas, common foundation pit supporting modes comprise cast-in-place piles, inner supports, pit bottom passive area reinforcement, piles in an SMW construction method, inner supports, pit bottom passive area reinforcement, underground continuous walls, inner supports, pit bottom passive area reinforcement and the like, and the conventional foundation pit supporting structures are large in risk or high in manufacturing cost. The open caisson is used as a foundation pit supporting structure to solve the problems, but the problems of inclination, deviation, sudden sinking, over sinking and the like easily occur in the open caisson construction process in the soft soil area, and once the problems occur, the problems are difficult to treat.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the invention provides a sunk well construction method which can ensure that a sunk well is safely, smoothly and accurately sunk to a preset position.

The open caisson construction method is characterized by comprising the following steps of: s100, installing a safety guardrail, finishing construction enclosure, and excavating a foundation pit slope-laying platform; s110, mounting the prestressed high-strength concrete pipe pile 104; s120, installing a cement-soil stirring bottom sealing pile and a cement-soil stirring pile; s130, in-situ casting a first section of open caisson section; s140, sinking the first section of open caisson; s150, casting a second open caisson section on the first open caisson section in a cast-in-place mode; s160, sinking the second section of open caisson in a segmented manner; s170, constructing open caisson underwater bottom sealing concrete, pouring an underground passage bottom plate, and backfilling foundation pit fertilizer groove plain concrete; s180, after the second steel pipe support is removed, construction of the side wall and the top plate of the underground passage is completed; s190, when the strength of a top plate and the strength of a side wall of the structure reach a preset value, backfilling a gap between the structure and the wall of the open caisson, and removing the first concrete support; and S200, backfilling the site above the top plate.

According to some embodiments of the present invention, in step S130, the cast-in-place first open caisson section is supported using a concrete support bottom girder and a second steel pipe.

According to some embodiments of the present invention, in step S150, after the first open caisson section reaches the predetermined position, a second open caisson section is cast in place on the first open caisson section.

According to some embodiments of the present invention, in step S170, the open caisson closing construction includes performing underwater closing construction using C30 plain concrete.

According to some embodiments of the invention, the back cover construction has a back cover thickness of 1.7-2.0 m.

According to some embodiments of the present invention, in step S170, when the stiffness reaches a predetermined value, the second steel pipe support is removed.

According to some embodiments of the present invention, in step S160 and step S170, the bottom sealing construction is started immediately after the second open caisson section is sunk in place.

By applying the open caisson construction method, during actual construction, the cement soil mixing pile installed firstly can play roles in stopping water and blocking silt and partially positioning, and the open caisson is ensured to be safely, smoothly and accurately sunk to a preset position.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

fig. 1 is a schematic view of a caisson pit bottom reinforcing structure in an embodiment of the invention;

FIG. 2 is a schematic view of a caisson support structure connected to an existing passage in accordance with an embodiment of the invention;

FIG. 3 is a schematic perspective view of a sectional type special-shaped open caisson according to an embodiment of the present invention;

fig. 4 is a schematic view of the butt joint of the first caisson section side wall and the second caisson section side wall in an embodiment of the invention;

FIG. 5 is a schematic sectional view of a foundation pit supporting structure of the open caisson in the embodiment of the invention;

FIG. 6 is an enlarged view taken at A in FIG. 2;

the above figures contain the following reference numerals.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

In the description of the present invention, it should be understood that the orientation or positional relationship referred to in the description of the orientation, such as the upper, lower, front, rear, left, right, etc., is based on the orientation or positional relationship shown in the drawings, and is only for convenience of description and simplification of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and more than, less than, more than, etc. are understood as excluding the present number, and more than, less than, etc. are understood as including the present number. If the first and second are described for the purpose of distinguishing technical features, they are not to be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.

In the description of the present invention, unless otherwise explicitly limited, terms such as arrangement, installation, connection and the like should be understood in a broad sense, and those skilled in the art can reasonably determine the specific meanings of the above terms in the present invention in combination with the specific contents of the technical solutions.

Referring to fig. 1, the construction method for reinforcing a deep silt stratum open caisson foundation pit in the first aspect of the embodiment includes the following steps: s100, installing a plurality of water stop piles 101 along the circumferential direction of a foundation pit; s200, mounting a plurality of first back cover piles 103 and a plurality of second back cover piles 105 at the bottom of the foundation pit, wherein the first back cover piles 103 are positioned on the periphery of the second back cover piles 105; and S300, installing the open caisson side wall 102 on the first bottom sealing pile 103.

By applying the construction method for reinforcing the open caisson foundation pit in the deep sludge stratum in the first aspect of the embodiment, during actual construction, the water stop piles 101 and the under-well wall reinforcing piles 103 are installed around the foundation pit, the reinforcing piles 105 are installed at the bottom of the foundation pit, and finally, open caisson operation is performed. In the open caisson operation process, the water stop piles 101 play a role of water stop curtains, so that the condition that the open caisson structure is inclined due to sand flowing in a local fine sand stratum and mud gushing in a deep mud layer in the open caisson sinking process is prevented; the well wall lower reinforcing pile 103 is used for improving the bearing capacity of the soil foundation under the blade foot of the open caisson and controlling the sinking speed of the open caisson; the reinforcing pile 105 in the foundation pit plays a role in controlling the uplift of the bottom of the foundation pit, guaranteeing the smooth construction of the bottom sealing of the open caisson, preventing the open caisson from being over-sunk or suddenly sunk, and protecting the main structure prestressed high-strength concrete pipe pile 104 which is constructed firstly.

As shown in fig. 1, in order to ensure the water-blocking effect of the water-blocking piles 101, in step S100, at least two circles of water-blocking piles 101 are sequentially arranged around the foundation pit from inside to outside; in the actual work progress, stagnant water stake can single row set up also can multirow overlap joint set up in order to improve the manger plate and end the silt effect.

Preferably, at least two circles of waterstops 101 overlap from inside to outside.

As shown in fig. 1, the thickness of the caisson side wall 102 is smaller than the reinforcement width of the first footer pile 103; at this time, the open caisson side wall 102 can fall onto the first plurality of bottom sealing piles 103 to control the open caisson sinking.

In step S100, the water-stopping pile 101 is manufactured by cement-soil stirring or high-pressure jet grouting; specifically, in step S100, the diameter of each water-stopping pile 101 is 600-; the diameter of each water stop pile 101 can be preferably 800mm, the center distance between two adjacent water stop piles 101 is preferably 600mm, the center distance between two adjacent water stop piles 101 is smaller than the diameter of each water stop pile 101, namely, the two adjacent water stop piles 101 are overlapped, and the sealing performance can be effectively improved.

Correspondingly, in step S200, the diameter of the second bottom-sealing pile 105 is 600-; the diameter of the second back cover piles 105 is preferably 800mm, the center distance between two adjacent second back cover piles 105 is preferably 600mm, and a certain overlap amount exists between two adjacent second back cover piles 105.

On the other hand, in step S200, the diameter of the first bottom-sealing pile 103 is 600-; preferably, the diameter of the first closed-end piles 103 is 800mm, and the center-to-center distance between two adjacent first closed-end piles 103 is 600mm, and there is a certain overlap between two adjacent first closed-end piles 103.

As shown in fig. 2, the foundation pit open caisson bottom reinforcing structure of the second aspect of this embodiment includes: a plurality of first back cover piles 103 and a plurality of second back cover piles 105, wherein the first back cover piles 103 are positioned at the bottom of the foundation pit, and the second back cover piles 105 are positioned at the periphery of the first back cover piles 103; the open caisson side wall 102 is arranged above the first bottom sealing pile 103, and the open caisson side wall 102 is positioned in the foundation pit; a plurality of stagnant water stake 101 are located the periphery of foundation ditch, and a plurality of stagnant water stake 101 overlap joint enclose into at least one round.

By applying the foundation pit open caisson bottom reinforcing structure of the second aspect of this embodiment, during actual construction, the water-stop piles 101 and the under-well wall reinforcing piles 103 are installed around the foundation pit, the reinforcing piles 105 are installed at the bottom of the foundation pit, and finally, open caisson operation is performed. In the open caisson operation process, the water stop piles 101 play a role of water stop curtains, so that the condition that the open caisson structure is inclined due to sand flowing in a local fine sand stratum and mud gushing in a deep mud layer in the open caisson sinking process is prevented; the well wall lower reinforcing pile 103 is used for improving the bearing capacity of the soil foundation under the blade foot of the open caisson and controlling the sinking speed of the open caisson; the reinforcing pile 105 in the foundation pit plays a role in controlling the uplift of the bottom of the foundation pit, guaranteeing the smooth construction of the bottom sealing of the open caisson, preventing the open caisson from being over-sunk or suddenly sunk and protecting the main structure constructed firstly.

Specifically, as shown in fig. 1, the water-stopping pile 101 is wound around the outer periphery of the foundation pit for a plurality of circles; the circles of water stop piles 101 overlap from inside to outside.

As shown in one of the first aspects of this embodiment, the thickness of the caisson side wall 102 is smaller than the reinforcement width of the first footer pile 103; the diameter of each water-stopping pile 101 is 600-800mm, and the center distance between two adjacent water-stopping piles 101 is 450-650 mm; the water stop piles 101 are wound around the outer periphery of the foundation pit in a plurality of turns.

Specifically, the diameter of the first capped pile 103 is 600-800mm, and the center distance between two adjacent first capped piles 103 is 450-650 mm.

As shown in fig. 2 and 6, the method for reinforcing the open caisson and the existing channel 210 according to the second aspect of the present embodiment includes the following steps: s100, mounting a first bottom sealing pile 103 and a second bottom sealing pile 105 at the bottom of a foundation pit, wherein the first bottom sealing pile 103 is positioned on the periphery of the second bottom sealing pile 105; s200, installing a concrete pipe pile on the second bottom sealing pile 105 along a preset position; s300, installing a side wall 102 of the open caisson on the first bottom sealing pile 103; and S400, installing the high-pressure jet grouting piles 202 between the side wall 102 of the open caisson and the existing channel 210, so that the high-pressure jet grouting piles 202 overlap the existing channel 210 and the side wall 102 of the open caisson.

By applying the method for reinforcing the open caisson and the existing channel 210 in the second aspect of the embodiment, in the actual construction process, after the open caisson construction is completed, the open caisson and the existing channel 210 are supported by the high-pressure jet grouting piles 202, so that the soil and water pressure outside the foundation pit can be effectively resisted under the condition that the distance between the open caisson and the existing channel 210 is small, and a working space is provided for the connection of a subsequently newly-built main body channel structure and the existing channel.

Specifically, in step S400, at least two rows of high-pressure jet grouting piles 202 are installed between the open caisson side wall 102 and the existing passage 210, and two ends of the high-pressure jet grouting piles 202 overlap the existing underground passage 210 and the open caisson side wall 102, respectively.

Specifically, in order to improve the supporting effect, in step S400, a plurality of mutually overlapped high-pressure jet grouting piles 202 are installed between the open caisson side wall 102 and the existing passage 210 in a rectangular distribution, and two ends of the array of rectangular high-pressure jet grouting piles 202 overlap the existing passage 210 and the open caisson side wall 102 respectively; specifically, as shown in fig. 2, two rectangular arrays of high-pressure jet grouting piles 202 may be disposed at both ends of the open caisson in the width direction, and the open caisson and the existing passage 210 are simultaneously supported at both sides, so that a distance of 3m to 4m can be maintained between the open caisson and the existing passage 210.

Specifically, in step S400, the high-pressure jet grouting pile 202 is installed, and then a hole is drilled in the high-pressure jet grouting pile 202 and a first steel pipe 203 is placed in the hole, wherein the length of the first steel pipe 203 is equal to the height of the jet grouting pile; the first steel pipe 203 can function as a micro steel pipe pile, and structural rigidity is enhanced.

In order to take the supporting performance of the steel pipe and the difficulty of installation construction into consideration, in step S400, the diameter of the first steel pipe 203 is 168mm, and the wall thickness of the first steel pipe 203 is 6 mm; of course, steel pipes of other specifications may be selected as necessary.

In order to further enhance the supporting effect, after the first steel pipe 203 is installed, the first steel pipe 203 is filled with a slurry by injecting the slurry into the first steel pipe 203 in step S400.

In order to further enhance the stability of the supporting structure, in step S400, after soil is excavated between the open caisson and the existing channel in layers, two steel pipes with a diameter of 609mm are arranged, and the support with a wall thickness of 12mm is welded and connected with the first steel pipe 203 through a steel plate.

As shown in fig. 2, when there are a plurality of high-pressure jet grouting piles 202, in step S400, a plurality of high-pressure jet grouting piles 202 are installed, the diameter of each high-pressure jet grouting pile 202 is 600-; preferably, the diameter of the high-pressure jet grouting pile 202 is 800mm, and the center distance between two adjacent high-pressure jet grouting piles 202 is 600 mm; at this time, a certain amount of overlap engagement exists between the adjacent high-pressure jet grouting piles 202.

The second aspect of the present embodiment of the reinforcing structure between the open caisson and the existing channel 210 includes: a plurality of first back cover piles 103 and second back cover piles 105, wherein the first back cover piles 103 are positioned at the bottom of the foundation pit, and the second back cover piles 105 are positioned at the periphery of the first back cover piles 103; the open caisson side wall 102 is arranged above the first bottom sealing pile 103, and the open caisson side wall 102 is positioned in the foundation pit; and the high-pressure jet grouting piles 202 are positioned between the side wall 102 of the open caisson and the existing channel 210, and the high-pressure jet grouting piles 202 overlap the side wall 102 of the open caisson and the existing channel 210.

By applying the reinforcing structure between the open caisson and the existing channel 210 in the second aspect of the embodiment, in the middle of actual construction, after the open caisson construction is completed, the open caisson and the existing channel 210 are supported by the high-pressure jet grouting pile 202, so that the water and soil pressure outside the foundation pit can be effectively resisted under the condition that the distance between the open caisson and the existing channel 210 is small, and a working space is provided for the connection of a subsequently newly-built main body channel structure and the existing channel.

As shown in fig. 2 and 6, at least two rows of overlapped high-pressure jet grouting piles 202 are arranged between the open caisson side wall 102 and the existing channel 210, and both ends of one row of high-pressure jet grouting piles 202 overlap the open caisson side wall 102 and the existing channel 210 respectively.

Specifically, a plurality of mutually overlapped high-pressure jet grouting piles 202 are distributed in a rectangular array between the open caisson side wall 102 and the existing channel 210, and two ends of the rectangular array formed by the high-pressure jet grouting piles 202 are respectively overlapped with the open caisson side wall 102 and the existing channel 210.

As shown in fig. 6, a first steel pipe 203 is provided inside the high-pressure jet grouting pile 202, and the first steel pipe 203 has the same length as the high-pressure jet grouting pile 202.

Specifically, in order to ensure that the internal structure of the high-pressure jet grouting pile 202 is stable and meanwhile, the steel pipe is convenient to install, the diameter of the first steel pipe 203 is 168mm, and the wall thickness of the first steel pipe 203 is 6 mm; of course, steel pipes of other specifications may be selected according to actual needs.

Specifically, the first steel pipe 203 is coaxial with the high-pressure jet grouting pile 202, and at this time, the first steel pipe 203 can exert a supporting function in each direction to the maximum extent.

As shown in fig. 3 and 4, the sectional type open caisson construction method according to the third aspect of the present embodiment includes the following steps: s100, mounting a first bottom sealing pile 103 and a second bottom sealing pile 105 at the bottom of a foundation pit, wherein the first bottom sealing pile 103 is positioned on the periphery of the second bottom sealing pile 105; s200, mounting a first open caisson segment side wall 310 on the first bottom sealing pile 103; s300, installing the second caisson segment sidewall 320 on the first footer pile 103, so that the first caisson segment sidewall 310 is butted against the second caisson segment sidewall 320.

By applying the sectional type open caisson construction method in the third aspect of the embodiment, in the actual construction of the ultra-long open caisson, the whole open caisson can be divided into multiple sections, and the open caisson sinks in sections after cast-in-place, so that the open caisson sinking posture can be conveniently adjusted in construction compared with the original one-time integral casting, and the difficult problem of construction difficulty of the ultra-long open caisson is solved.

As shown in fig. 3, in actual construction, when there are multiple caisson section side walls, the construction sequence should be to install the special-shaped caisson section side wall 330, the first caisson section side wall 310, the second caisson section side wall 320, and the curved caisson section side wall 340 in sequence.

In order to avoid too many sections of the ultra-long open caisson and shorten the construction period of the open caisson, in step S200, after the second intermediate wall 321 is installed in the side wall 320 of the second open caisson section, the side wall 320 of the second open caisson section and the second intermediate wall 321 are integrally cast for sinking at one time; the overall rigidity of the open caisson structure can be improved, so that the once sinking length of the open caisson is improved to 60-70 m from about 30-35 m, and the construction efficiency is greatly improved.

Specifically, septum secundum 321 has a thickness of at least 400 mm; the integral rigidity of the open caisson at the section is ensured, so that the open caisson structure is safely and smoothly sunk.

As shown in fig. 2, in order to perform the function of the intermediate wall as much as possible in the case of saving the material of the intermediate wall, a second intermediate wall 321 is positioned at the middle of the side wall 320 of the second caisson section and is perpendicular to the length direction of the side wall 320 of the second caisson section.

As shown in fig. 4, the second caisson section includes a second butt joint structure 322, the second butt joint structure 322 includes a web portion and flange portions disposed at both sides of the web portion, and the flange portions are butted against the first caisson section side walls 310; in the open caisson segment construction, the first open caisson segment side wall 310 can be sunk firstly, then the second open caisson segment side wall 320 can be sunk, and the butt joint position between the segments can be adjusted by breaking the flange part, so that the problem that the open caisson can not sink due to larger sinking error caused by segmenting the open caisson can be effectively solved; specifically, as shown in fig. 4, the web and flange portions together form an i-shaped abutment.

As shown in fig. 4, in order to satisfy construction errors caused by the sublevel sinking of the open caisson and satisfy the stress requirements of the flange part, the overhanging part of the flange should not be too long, and the length of the flange part is 1400-1800 mm; the length of the flange part is preferably 1500 mm.

Specifically, in order to ensure that the distance between the two open caisson segment sidewalls is not too large while a certain adjustment margin is retained, the distance between the flange portion and the first open caisson segment sidewall 310 is 250-400mm, preferably 300 mm.

As shown in fig. 4, in order to reduce the influence of the sludge and the drift sand when the second caisson section sidewall 320 is sunk, step S200 further includes: before the first open caisson section side wall 310 is installed, a Larsen steel sheet pile 313 is installed between the second open caisson section side wall 320 and the first open caisson section side wall 310; and sinking the second open caisson side wall section 320 after installing the Larsen steel sheet pile 313, wherein the Larsen steel sheet pile 313 can play a role in stopping water and blocking silt.

Specifically, the size of the larsen steel sheet pile 313 is preferably SP-IV, the length of the larsen steel sheet pile 313 is set to be 17-19m, preferably 18m, and particularly, after the first section of the caisson side wall 310 is completed, the larsen steel sheet pile at the position needs to be pulled out and recovered.

The second sectional type open caisson structure in the third aspect of the present embodiment comprises: a plurality of first back cover piles 103 and second back cover piles 105, wherein the first back cover piles 103 are positioned at the bottom of the foundation pit, and the second back cover piles 105 are positioned at the periphery of the first back cover piles 103; a first open caisson segment side wall 310, arranged at the upper end of the first bottom sealing pile 103; and a second caisson section side wall 320, which is arranged at the upper end of the first bottom sealing pile 103, wherein the second caisson section side wall 320 is butted with the first caisson section side wall 310.

By applying the sectional type open caisson structure of the second aspect of the embodiment, in the actual construction of the ultra-long open caisson, the whole open caisson can be divided into multiple sections, and the open caisson sinks in sections after cast-in-place, so that the sinking difficulty can be effectively reduced and the problem that the ultra-long open caisson is difficult to sink is solved compared with the original overall sinking scheme.

Referring to one of the third aspects of this embodiment, a second middle partition 321 is disposed in the second caisson section side wall 320, the thickness of the second middle partition 321 is at least 400mm, and the second middle partition 321 is perpendicular to the long side direction of the second caisson section side wall 320.

On the other hand, the second caisson section comprises a second butt joint structure 322, the second butt joint structure 322 comprises a web part and flange parts arranged on two sides of the web part, and the flange parts are butted with the side walls 310 of the first caisson section; the length of the flange part is 1600-1800 mm; the distance between the flange part and the sidewall 310 of the first caisson section is 250-400 mm.

The sectional type open caisson structure further comprises Larsen steel sheet piles 313, wherein the Larsen steel sheet piles 313 are located between the second open caisson section side walls 320 and the first open caisson section side walls 310; the length of the Larsen steel plate pile 313 is 17-19 m.

It will be appreciated that with reference to the first aspect of the present embodiment, a plurality of water stop piles 101 may also be provided at the periphery of the segmented caisson structure, such that the plurality of water stop piles 101 are located at the periphery of the first caisson segment side wall 310 and the second caisson segment side wall 320; plays the role of blocking the silt and stopping water.

As shown in fig. 3, the construction method of the special-shaped open caisson according to the fourth aspect of the present embodiment includes the following steps: s100, installing a plurality of first bottom sealing piles 103 and a plurality of second bottom sealing piles 105 at the bottom of a foundation pit, wherein the first bottom sealing piles 103 are positioned on the periphery of the second bottom sealing piles 105; s200, installing a special-shaped open caisson section side wall 330 on the first bottom sealing pile 103, wherein the special-shaped open caisson section side wall 330 is provided with a plurality of extension parts; s300, mounting the second caisson segment sidewall 320 on the first footer pile 103 so that the second caisson segment sidewall 320 is butted against one of the extensions.

By applying the construction method of the special-shaped open caisson in the fourth aspect of the present embodiment, in the actual construction of the special-shaped open caisson, the whole special-shaped open caisson can be divided into multiple sections including the special-shaped open caisson section side wall 330 and the linear open caisson section side wall, then the special-shaped open caisson section side wall 330 is firstly sunk, then the linear open caisson section side wall is sunk and is in butt joint with the special-shaped open caisson section, and compared with the original overall sinking scheme, the sinking difficulty can be effectively reduced, and the problem that the special-shaped open caisson is difficult to construct is solved.

In the present embodiment, as shown in fig. 3, the special-shaped open caisson refers to an open caisson having at least 3 extending directions that are not in a straight line; likewise, the shaped caisson section sidewall 330 refers to a caisson section sidewall having at least 3 extensions that are not in a straight line.

As shown in fig. 3, in order to ensure the rigidity of the special-shaped open caisson segment side wall 330, in step S200, after the third intermediate wall 331 is installed in the special-shaped open caisson segment side wall 330, the special-shaped open caisson segment side wall 330 and the third intermediate wall are integrally cast and sunk; the third intermediate wall 331 can enhance the overall rigidity of the special-shaped open caisson, improve the bending resistance and the torsion resistance of the special-shaped open caisson, and facilitate the adjustment of the open caisson posture in the sinking process.

Specifically, when the shaped caisson section sidewall 330 is configured in a T-shape, the shaped caisson section sidewall 330 has three extensions, and a third intermediate wall 331 is installed on each extension inner wall.

In order that the three third intermediate walls 331 can form a support between each other while supporting the special-shaped open caisson section side walls 330, the three third intermediate walls 331 surround a support system formed in a triangular shape in cross section.

As shown in fig. 3 and 4, a second butting structure 322 is disposed on the second caisson segment sidewall 320, the second butting structure 322 includes a web portion and flange portions disposed on two sides of the web portion, and the flange portions are butted with the extending portions; and when the second open caisson sinks in a subsection mode, the I-shaped connector is used for adjusting the butt joint position.

In the third and fourth aspects of the present embodiment, the i-shape acts similarly to the joint.

Specifically, the length of the flange part is 1400-1800mm, preferably 1500 mm; the distance between the flange part and the side wall 330 of the special-shaped open caisson section is 250-400mm, and preferably 300 m.

As shown in fig. 3, the construction method of the special-shaped open caisson further includes a step S400, where the step S400 includes: mounting the curved open caisson segment side walls 340 on the first footer piles 103 so that the second open caisson segment side walls 320 and the curved open caisson segment side walls 340 are each butted by an extension; by means of sectional construction, the problem that the curve open caisson is difficult to sink is effectively solved.

In order to facilitate the butt joint of the curved open caisson section side wall 340 and the extension part, a third butt joint structure 342 is arranged on the curved open caisson section side wall 340, and the third butt joint structure 342 is in butt joint with the extension part; as shown in fig. 3, the third docking structure 342 is also an i-shaped docking head.

In order to enhance the rigidity of the curved open caisson segment sidewall 340, the curved open caisson segment sidewall 340 is provided with a fourth intermediate wall 341; in sinking, the fourth intermediate wall 341 may be installed inside the curved open caisson section sidewall 340 and then sunk as a whole.

Specifically, in the sinking process of the special-shaped open caisson, soil bodies are dug in a layered mode, and meanwhile control over the sinking posture of the open caisson is enhanced, wherein the monitoring of the sinking posture of the open caisson is divided into two monitoring parts, namely a vertical height difference monitoring part and a horizontal deviation monitoring part; in the vertical elevation difference monitoring, the elevation difference of the centers of any two vertex centers in the four corners of the open caisson is controlled to be not more than 1 percent of the horizontal distance of the two corners and not more than 150 mm; in the horizontal deviation monitoring, the control value is that the horizontal displacement of the center of the top surface of the open caisson is not more than 1% of the total sinking height, and when the total sinking depth is less than 10m, the control value is not more than 100 mm; the monitoring frequency is not less than 2 times per group.

The second special-shaped open caisson structure of the fourth aspect of the present embodiment comprises: a plurality of first closed-end piles 103 and a plurality of second closed-end piles 105, which are positioned at the bottom of the foundation pit, wherein the plurality of first closed-end piles 103 are positioned at the periphery of the plurality of second closed-end piles 105; the special-shaped open caisson section side wall 330 is arranged at the upper end of the first bottom sealing pile 103, and the special-shaped open caisson section side wall 330 is provided with a plurality of extension parts; and a second caisson section sidewall 320, disposed at the upper end of the first footer pile 103, the second caisson section sidewall 320 abutting one of the extensions.

By applying the special-shaped open caisson structure of the second aspect of the embodiment, in the actual construction of the special-shaped open caisson, the whole special-shaped open caisson can be divided into a plurality of sections including special-shaped sections and straight line sections, then the special-shaped open caisson section is firstly sunk, then other sections are sunk and are in butt joint with the special-shaped open caisson section, and compared with the original overall sinking scheme, the sinking difficulty can be effectively reduced, and the problem that the special-shaped open caisson is difficult to sink is solved.

Referring to one of the fourth aspects of the present embodiment, a third intermediate wall 331 is disposed in the sidewall 330 of the special-shaped open caisson section.

Specifically, the special-shaped open caisson section side wall 330 has three extension parts, and a third intermediate wall 331 is installed on the inner wall of each extension part; the three third intermediate walls 331 surround a support system formed in a triangular shape in cross section.

As shown in fig. 3, a second docking structure 322 is disposed on the second caisson section side wall 320, the second docking structure 322 includes a belly portion and flange portions disposed on two sides of the belly portion, and the flange portions are docked with the extension portions; the length of the flange part is 1400-1800mm, preferably 1500 mm; the distance between the flange part and the side wall 320 of the second open caisson section is 250-400mm, preferably 300 mm.

Specifically, the special-shaped open caisson structure further comprises a curved open caisson section side wall 340, and the second open caisson section side wall 320 and the curved open caisson section side wall 340 are respectively butted with an extension part; a third butt joint structure 342 is arranged on the side wall 340 of the curved open caisson section, and the third butt joint structure 342 is in butt joint with the extension part; a fourth intermediate wall 341 is provided in the curved caisson section sidewall 340.

The open caisson construction method in the fifth aspect of the present embodiment includes the following steps: s100, installing a safety guardrail 401, completing construction enclosure, and excavating a foundation pit slope-laying platform; s110, mounting the prestressed high-strength concrete pipe pile 104; s120, installing a cement-soil stirring bottom sealing pile 406 and a cement-soil stirring pile 402; s130, in-situ casting a first section of open caisson section; s140, sinking the first section of open caisson; s150, casting a second open caisson section on the first open caisson section in a cast-in-place mode; s160, sinking the second section of open caisson in a segmented manner; s170, constructing open caisson underwater bottom sealing concrete, pouring an underground passage bottom plate, and backfilling foundation pit fertilizer groove plain concrete; s180, after the second steel pipe support 403 is removed, construction of the side wall and the top plate of the underground passage is completed; s190, when the rigidity of a top plate and the rigidity of a side wall of the structure reach a preset value, backfilling a gap between the structure and the wall of the open caisson, and removing the first concrete support; and S200, backfilling the site above the top plate.

By applying the open caisson construction method of the fifth aspect, during actual construction, the cement soil mixing pile 402 installed first can play roles in stopping water and blocking silt and partially positioning, and the open caisson can be safely, smoothly and accurately sunk to a preset position.

Specifically, as shown in fig. 5, in step S130, the first caisson section is composed of at least a concrete-supported bottom beam and a second steel pipe support 403, and the first caisson section is cast in situ on site and then sunk, so that the transportation cost can be effectively reduced.

Further, in step S150, after the first open caisson segment is sunk to the predetermined position, the second open caisson segment is cast in situ on the first open caisson segment on site, and the segmental casting sinking avoids the construction risk of building a high and large formwork caused by one-time sinking, and overcomes the disadvantages of insufficient foundation bearing capacity at the edge foot of the open caisson and poor stability of the open caisson sinking.

In practical construction, the first support horizontal spacing is preferably 4-6m, and the preferred support horizontal spacing is 5 m; the horizontal spacing of the second support is preferably 4-6m, and the preferred horizontal spacing of the supports is 5 m; the horizontal spacing of the third support is preferably 4-6m, and the preferred horizontal spacing of the supports is 5 m.

Specifically, a concrete support bottom beam and a second steel pipe support 403 are cast in situ on the first open caisson segment, and a concrete support top beam 404 is cast in situ on the second open caisson segment.

Furthermore, in order to reduce the manufacturing cost and accelerate the construction progress, the first open caisson is sunk and the earthwork excavation is carried out by adopting a dry operation method, and in order to control the influence of the open caisson sinking on the surrounding environment, the second open caisson is sunk and the underwater earthwork excavation is carried out by adopting water-carrying operation.

As shown in fig. 5, the open caisson bottom sealing construction comprises the step of performing underwater bottom sealing construction by using C30 plain concrete; after the bottom sealing construction is completed, a construction space is created for the main structure.

Wherein, in order to save the cost and ensure the stability of the pit bottom, the thickness of the back cover for back cover construction is 1.7-2.0m, preferably 1.8 m.

According to the construction requirements, after the channel bottom sealing construction, the second steel pipe support 403 needs to be removed, the main structure construction is carried out, in step S160 and step S170, when the second open caisson is sunk in place in a subsection mode, the bottom sealing construction is started immediately, and after the bottom sealing construction and the main structure bottom plate pouring are completed, the second steel pipe support 403 can be removed.

Similarly, according to the construction requirements, the concrete support top beam 404 is completed on the main structure, the structural strength reaches the design rigidity, and the foundation pit fertilizer tank is removed after backfilling to the elevation of the structural top plate.

The second open caisson foundation pit supporting structure of the fifth aspect of this embodiment includes: two rows of cement mixing piles 402 arranged at intervals are distributed on the outer side of the foundation pit; the multiple cement-soil stirring bottom sealing piles 406 are arranged at the bottom of the foundation pit, and the multiple cement-soil stirring bottom sealing piles 406 are in lap joint with the two rows of cement-soil stirring piles 402; the first open caisson section is arranged at the upper end of the cement-soil stirring back cover; and the second open caisson section is arranged at the upper end of the first open caisson section.

By applying the open caisson foundation pit supporting structure of the second aspect of the present embodiment, during actual construction, the cement-soil mixing pile 402 installed first can play a role in stopping water and blocking silt and partially positioning, thereby ensuring that the open caisson is safely, smoothly and accurately sunk to a predetermined position.

Referring to one of the fifth aspects of the present embodiment, the first open caisson section comprises a concrete support bottom beam and a second steel pipe support 403, and the second steel pipe support 403 is located above the concrete support bottom beam; the second open caisson section comprises a concrete support top beam 404, and the concrete support top beam 404 is positioned above the second steel pipe support 403; the second steel pipe support 403 is detachably disposed.

Wherein, the well wall is provided with three supports, the first support is a concrete support top beam 404, the second support is a steel pipe support 403, and the third support is a concrete bottom support beam.

Similarly, the open caisson foundation pit supporting structure further comprises a concrete back cover 405, and the concrete back cover 405 covers the concrete support bottom beam; the thickness of the concrete back cover 405 is 1.7-2.0 m.

As shown in fig. 5, in order to improve the sinking stability of the open caisson, reduce the requirement of the bearing capacity of the foundation during the manufacturing of the open caisson, and avoid the risk of constructing a high and large template, the height of the first open caisson segment is 4-5 m.

As shown in fig. 1, in order to ensure the water-stopping and silt-stopping effects of the cement-soil mixing pile 402, the portion of the cement-soil mixing pile 402 embedded below the bottom of the foundation pit is at least 6 m; preferably 8 m.

The diameter of the cement-soil stirring bottom sealing pile 406 is 600-800mm, preferably 800mm, and the center distance between two adjacent cement-soil stirring bottom sealing piles 406 is 450-650mm, preferably 600 mm.

It should be noted that, in the present embodiment, the method and the structure of several aspects can be used in cooperation with each other and in a modular manner, for example, the reinforcing method and the reinforcing structure of the first aspect are used in construction of a segmented open caisson or a special-shaped open caisson, and the like.

The embodiments of the present invention have been described in detail with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the gist of the present invention.

Claims (7)

1. A method for constructing an open caisson is characterized by comprising the following steps:

s100, installing a safety guardrail (401), completing construction enclosure, and excavating a foundation pit slope-laying platform;

s110, mounting a prestressed high-strength concrete pipe pile (104);

s120, installing a cement-soil stirring bottom sealing pile (406) and a cement-soil stirring pile (402);

s130, in-situ casting a first section of open caisson section;

s140, sinking the first section of open caisson;

s150, casting a second open caisson section on the first open caisson section in a cast-in-place mode;

s160, sinking the second section of open caisson in a segmented manner;

s170, constructing open caisson underwater bottom sealing concrete, pouring an underground passage bottom plate, and backfilling foundation pit fertilizer groove plain concrete;

s180, after the second steel pipe support (403) is removed, construction of the side wall and the top plate of the underground passage is completed;

s190, when the rigidity of a top plate and the rigidity of a side wall of the structure reach a preset value, backfilling a gap between the structure and the wall of the open caisson, and removing the first concrete support;

and S200, backfilling the site above the top plate.

2. The open caisson construction method of claim 1, wherein in step S130, the first open caisson segment is cast-in-place using a concrete-supported bottom beam and a second steel pipe support (403).

3. The open caisson construction method of claim 2, wherein in step S150, after the first open caisson section is sunk to the predetermined position, a second open caisson section is cast in situ on the first open caisson section.

4. The caisson construction method of claim 1, wherein, in step S170, the caisson bottom-sealing construction comprises performing underwater bottom-sealing construction using C30 plain concrete.

5. The open caisson construction method of claim 4, wherein the back cover construction has a back cover thickness of 1.7-2.0 m.

6. The open caisson construction method of claim 1, wherein in step S170, when the stiffness reaches a predetermined value, the second steel pipe support (403) is removed.

7. The method of claim 1, wherein the bottom closure construction is started immediately after the second open caisson section is sunk in place in steps S160 and S170.

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