CN115559334A - Pebble-floating stratum cofferdam device and construction method thereof - Google Patents

Abstract

The application belongs to the technical field of bridge construction, and particularly relates to a pebble-drift stratum cofferdam device and a construction method thereof. When cofferdam construction is carried out in the boulder stratum, the steel sheet pile and the steel sleeve box can not reach the installation position efficiently, so that the construction process is complex, and the construction efficiency is low. According to the pebble floating stratum cofferdam device and the construction method thereof, when the cofferdam is constructed, the construction method of arranging the foundation trench in the cofferdam is adopted, so that the cofferdam can reach the installation position, and the problem of construction accidents caused by easy cracking and collapse of the pebble floating stratum in construction is avoided; the excavated soil and stones can be repeatedly utilized for backfilling after being screened, and a good supporting effect is achieved. No matter the cofferdam adopts steel sheet pile or steel bushing box construction, all demonstrate better structural stability. The device has a simple structure, shortens the construction period, improves the construction efficiency and has better economy; the cofferdam construction in the boulder stratum is facilitated, and the cofferdam construction method is suitable for popularization and application in the industry.

Description

Pebble-floating stratum cofferdam device and construction method thereof

Technical Field

The application relates to the technical field of bridge construction, in particular to a pebble-drift stratum cofferdam device and a construction method thereof.

Background

The boulder stratum belongs to a typical non-homogeneous stratum and is a stratum with typical particle characteristics, which is composed of boulders, pebbles, medium and coarse gravel and clay with different particle sizes. Most of the boulder layers are ice water sediments, stratum particles are not uniform, large boulders and small boulders are mixed and deposited together, the sorting property is poor, and the stratum is compact. The boulder stratum has the advantages of fast water-rich permeability, weak cementation and poor self-stability, and easily causes river bottom cracking and collapse.

In the bridge foundation construction, when bridge piers and platform foundations are positioned below the ground surface water level, earth weirs in various forms are built according to local materials; the cofferdam with wooden piles or steel sheet piles can be adopted in rivers with deep water and large flow velocity. The cofferdam can prevent water and enclose water and can support the pit wall of the foundation pit. The steel sheet pile cofferdam is the most commonly used one. The steel sheet pile is a section steel with locking notch, and its section has straight plate shape, groove shape and Z shape, and has various sizes and interlocking forms. The Larson type, lake Mo Na and the like are common. Its advantage does: the strength is high, and the soil can be easily driven into a hard soil layer; the coating can be constructed in deep water and has good waterproof performance; the cofferdam with various shapes can be formed according to the requirement and can be repeatedly used, so that the application of the cofferdam is wide.

A bridge foundation in a pebble-drift stratum is usually constructed by adopting a steel cofferdam, and the commonly used steel cofferdam structure comprises a steel sheet pile cofferdam, a steel sleeve box and the like. However, due to the geological reasons of the pebble-floated stratum, the steel sheet piles cannot be directly inserted and driven into the pebble-floated stratum, and the steel sleeve box cannot be directly sunk. The conventional steel sheet pile often needs to adopt the mode of drilling and leading the hole to beat and establishes the steel sheet pile or to adopt and circulate in proper order and beat the mode of establishing the steel sheet pile while digging in the boulder stratum and carry out the steel sheet pile and beat and establish, in addition, adopts steel boxed cofferdam also to need the construction mode of digging while sinking, and these two kinds of construction scheme all lead to the construction process complicated, and the efficiency of construction is lower. Therefore, a pebble-drift stratum cofferdam device with simplified process, high efficiency, convenience and better economical efficiency and a construction method thereof are urgently needed.

Disclosure of Invention

The application provides a pebble-drift stratum cofferdam device and a construction method thereof, which aim to solve the problems of complex construction process and lower construction efficiency in the existing pebble-drift stratum cofferdam construction.

The technical scheme adopted by the application is as follows:

in a first aspect of the application, a pebble-floating stratum cofferdam device is provided, which comprises a cofferdam placing foundation trench, a cofferdam outer backfilling part, a cofferdam body, a cofferdam bottom sealing, a periphery jail and an inner wailing;

the cofferdam placing foundation groove is used for floating a pebble stratum by Yu Zudang, and the pebble stratum is separated from the cofferdam body;

the outer side backfilling part of the cofferdam is used for filling a spacing area between the cofferdam placing foundation trench and the cofferdam body;

the cofferdam body is a steel sheet pile cofferdam;

the cofferdam back cover is arranged at the bottom of the inner side of the cofferdam body;

the outer wails are made of channel steel or profile steel, are arranged on the outer side face of the cofferdam weir body and are used for fixing the cofferdam weir body from the outer side;

the inner wailing is arranged on the inner side of the cofferdam weir body and used for the inner support of the cofferdam weir body.

Optionally, the cofferdam device further comprises a cofferdam positioning device;

the cofferdam positioning device is arranged on the outer side edge of the cofferdam body, and the outer side backfilling part of the cofferdam is used for filling a spacing area between the cofferdam placing foundation trench and the cofferdam positioning device.

Optionally, the system further comprises a man-in-and-out hole;

the man-in-and-out hole is formed in the cofferdam weir body, the lower part of the man-in-and-out hole is composed of short steel sheet piles of the cofferdam weir body, and the upper part of the man-in-and-out hole is composed of movable steel sheet piles;

the movable steel sheet pile is arranged at the top end of the upper part of the short steel sheet pile in a low water level period to form a man-in-and-out hole;

the movable steel sheet pile is arranged at the upper end of the short steel sheet pile in a high water level period and is in butt joint with the short steel sheet pile to seal the man-hole.

Optionally, the steel bar fixing device further comprises a Z-shaped fixing steel bar;

the Z-shaped fixing steel bar is arranged between external wails and internal wails and is used for fixedly connecting the external wails and the internal wails;

one end of the Z-shaped fixed steel bar is provided with a hook which is hooked at the lower edge of the inner side of the inner periphery jail, and the other end of the Z-shaped fixed steel bar is provided with a hook which is hooked on the outer periphery wailing.

Optionally, an inner support is further included;

two ends of the inner support are respectively and oppositely fixedly arranged on the inner wailing.

In a second aspect of the present application, a cobble stratum cofferdam construction method is provided, which is based on the cobble stratum cofferdam device, and includes the following steps:

carrying out slope lowering, water lowering and slope digging on a cofferdam foundation pit to reach the edge of the bottom of the preset concrete at the bottom sealing of the cofferdam;

arranging cofferdam placing foundation grooves for blocking the boulder stratum at the edge part;

inserting and beating steel sheet piles to form a cofferdam weir body, fixedly installing outer wails and inner wails jail on the outer side and the inner side of the cofferdam weir body, and installing the cofferdam weir body at the edge of the bottom of preset concrete;

pouring concrete at the bottom of the cofferdam body to form a cofferdam back cover;

and backfilling a foundation pit in the interval area between the cofferdam body and the cofferdam placing foundation trench to form a backfilling part at the outer side of the cofferdam.

Optionally, after the step of setting a cofferdam placement foundation trench for blocking the pebble layer at the edge, the method further includes:

and (2) arranging a cofferdam positioning device, inserting and driving steel sheet piles along the cofferdam positioning device to form a cofferdam body, and backfilling a foundation pit in a spacing area between the cofferdam positioning device and the cofferdam placing foundation trench to form a backfilling part at the outer side of the cofferdam.

Optionally, inserting and beating the steel sheet piles to form a cofferdam weir body, fixedly installing outer wails and inner wails jail at the outer side and the inner side of the cofferdam weir body, and installing the cofferdam weir body in the step of presetting the edge of the bottom of the concrete, further including:

an in-out man hole is formed in the cofferdam weir body, the lower part of the in-out man hole consists of short steel sheet piles of the cofferdam weir body, and the upper part of the in-out man hole consists of movable steel sheet piles;

the movable steel sheet pile is arranged at the top end of the upper part of the short steel sheet pile in a low water level period to form a man-in-and-out hole;

and the movable steel sheet pile is arranged at the upper end of the short steel sheet pile in a high water level period and is in butt joint with the short steel sheet pile to seal the access man hole.

Optionally, inserting and beating the steel sheet piles to form a cofferdam weir body, fixedly installing outer wails and inner wails jail at the outer side and the inner side of the cofferdam weir body, and installing the cofferdam weir body in the step of presetting the edge of the bottom of the concrete, further including:

z-shaped fixed steel bars are arranged between the outer wails and the inner wails and are used for fixedly connecting the outer wails and the inner wails;

one end of each Z-shaped fixed steel bar is provided with a hook which is hooked at the lower edge of the inner side of the inner periphery jail, and the other end of each Z-shaped fixed steel bar is provided with a hook which is hooked at the outer periphery wail.

Optionally, the inserting and beating steel sheet pile forms a cofferdam weir body, external wails and internal wails jail are fixedly installed on the outer side and the inner side of the cofferdam weir body, and the cofferdam weir body is installed in the step of presetting the edge of the bottom of concrete, and the method further includes:

an inner support is fixedly arranged on the inner wailing, and two ends of the inner support are respectively and oppositely and fixedly arranged on the inner wailing.

The technical scheme of the application has the following beneficial effects:

according to the pebble floating stratum cofferdam device and the construction method thereof, when the cofferdam is constructed, the construction method of arranging foundation grooves on the cofferdam is adopted, the cofferdam can reach the installation position favorably, the problem that construction accidents are caused by easy cracking and collapse of the pebble floating stratum in construction is avoided, excavated earth and stones can be repeatedly utilized for backfilling after screening, and a good supporting effect is achieved. No matter the cofferdam adopts steel sheet pile or steel bushing box construction, all demonstrate better structural stability. The device has a simple structure, shortens the construction period, improves the construction efficiency to a certain extent, and has better economy; the cofferdam construction in the boulder stratum is facilitated, and the cofferdam construction method is suitable for popularization and application in the industry.

Drawings

In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic structural diagram of an embodiment of a first aspect of the present application;

FIG. 2 is a schematic structural diagram of another embodiment of the first aspect of the present application;

FIG. 3 is a schematic partial structural view of a further embodiment of the first aspect of the present application;

fig. 4 is a schematic structural diagram of a cofferdam positioning device in the first aspect of the present application;

FIG. 5 is a schematic structural diagram of an in-out manhole in an embodiment of the first aspect of the present application;

fig. 6A is a schematic view illustrating the installation of Z-shaped fixing bars according to an embodiment of the first aspect of the present application;

FIG. 6B is a schematic view of an embodiment of a Z-shaped fixation bar of the present application;

FIG. 7 is a flow chart of an embodiment of a second aspect of the present application;

illustration of the drawings:

the cofferdam comprises 1-cofferdam placing foundation groove, 2-cofferdam outer backfill part, 3-cofferdam body, 4-cofferdam sealing bottom, 5-outer wailing, 6-inner wailing, 7-cofferdam positioning device, 71-guide frame upright post, 72-guide frame transverse and bridge-directional support, 73-guide frame longitudinal and bridge-directional support, 8-in and out people hole, 81-upper people hole steel plate pile, 82-lower people hole steel plate pile, 9-Z type fixed steel bar, 10-inner support, 11-pile foundation and 12-bearing platform.

Detailed Description

Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings. When the following description refers to the accompanying drawings, like numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following examples do not represent all embodiments consistent with the present application. But merely as exemplifications of systems and methods consistent with certain aspects of the application, as recited in the claims.

The foundation pit dewatering refers to dewatering work performed for ensuring that the foundation pit can be constructed under a dry condition and preventing slope instability, foundation quicksand, pit bottom uplift, pit bottom piping and foundation bearing capacity reduction when the underground water level is higher than the excavation bottom surface when the foundation pit is excavated.

In a first aspect of the application, a pebble-floating stratum cofferdam device is provided, and comprises a cofferdam placing base groove 1, a cofferdam outer backfilling part 2, a cofferdam body of a cofferdam body 3, a cofferdam back cover 4, a periphery jail and an wailing 6;

the cofferdam placing base groove 1 is used for blocking a boulder stratum and separating the boulder stratum from the cofferdam body 3;

the cofferdam outer side backfilling part 2 is used for filling a spacing area between the cofferdam placing foundation trench 1 and the cofferdam body 3;

the cofferdam body 3 is a steel sheet pile cofferdam;

the cofferdam back cover 4 is arranged at the bottom of the inner side of the cofferdam body 3;

the outer wails 5 are made of channel steel or profile steel, are arranged on the outer side surface of the cofferdam weir body 3 and are used for fixing the cofferdam weir body 3 from the outer side;

the inner wailing 6 is arranged on the inner side of the cofferdam weir body 3 and is used for an inner support 10 of the cofferdam weir body 3.

Referring to fig. 1, in this embodiment, a foundation pit is firstly excavated in the outer backfilling portion 2 of the cofferdam, then steel sheet piles are inserted and driven to form a cofferdam body 3, and after bottom sealing concrete, i.e., a cofferdam bottom seal 4, is poured, the outer side of the cofferdam body 3 is backfilled by using backfill materials of sand or gravel or fine soil to form the outer backfilling portion 2 of the cofferdam, and the outer backfilling portion 2 of the cofferdam can block water and also can play a role in supporting the cofferdam body 3.

In some embodiments, considering that steel sheet piles cannot enter soil for fixation during inserting and driving, the cofferdam weir body 3 has the risk of falling to the outside, and the outer wall 5 is provided, the outer wall jail may be made of channel steel or profile steel, the notch of the channel steel is downward when the channel steel is adopted, and the strong shaft of the channel steel is horizontally arranged when the profile steel is adopted. In other embodiments, the distance between the inner periphery jail and the outer periphery jail is 5mm in consideration of the buckling requirement of the steel sheet pile, namely the distance between the inner periphery jail and the outer periphery 3763 is d +5 mm.

In some embodiments, the periphery jail can be made of channel steel or section steel, and the cofferdam outer side backfill part 2 can be made of sand or sand gravel or fine soil, so that excavated materials after foundation pit excavation can be recycled.

In some embodiments, the cofferdam installation foundation trench 1 is used as a foundation pit of the steel sheet pile cofferdam body structure, and is a key structure for ensuring the steel sheet pile cofferdam body structure to be installed in place. The conventional steel sheet pile cofferdam is formed by directly driving steel sheet piles in a stratum through vibration and sinking and then excavating the cofferdam, but the steel sheet piles cannot sink in a pebble-floating stratum due to the blocking effect of pebbles, so that the steel sheet piles cannot be applied to the pebble-floating stratum. The cofferdam placing foundation trench 1 is arranged to adopt dewatering excavation, and boulders in the range of the cofferdam are excavated and cleaned by adopting an excavator, so that the problem that a steel sheet pile sinks is solved. And (4) putting a slope in the boulder stratum provided with the cofferdam to reduce water and excavate a cofferdam foundation pit, and excavating the foundation pit to the bottom sealing surface. And (3) adopting a digging machine to place a slope to excavate the cofferdam foundation pit, excavating according to an excavation mode of firstly excavating the center and then excavating the periphery, and excavating the position far away from the pile foundation 11 firstly and then excavating the periphery of the pile foundation 11. The excavator adopts a high-power excavator to ensure that the large boulder soil can be excavated. The boulders which are difficult to dig out can be matched with a breaking hammer to break and decompose underwater, and if the water is deep, a high-power water pump can be arranged to pump water. The depth of the foundation pit must be enough to be excavated, and the excavation depth is measured by the full coverage of the measuring rope, so that the thickness of the bottom sealing concrete must meet the requirement.

The cofferdam weir body 3 is a water blocking structure for the cofferdam, and exemplarily, the cofferdam weir body 3 can adopt steel sheet piles, steel casing boxes can be inserted and beaten according to a certain sequence, and the steel casing boxes can also be adopted.

The cofferdam back cover 4 is arranged at the bottom of the inner side of the cofferdam body structure of the steel sheet pile cofferdam and is used for water blocking at the bottom of the cofferdam body 3 and supporting the bottom of the cofferdam, and a concrete structure is generally adopted.

In some embodiments, because excavation cofferdam lays foundation trench 1, lead to the foundation trench to be greater than steel sheet pile cofferdam weir body structure, there is the phenomenon of no support in the steel sheet pile cofferdam 3 structures outside promptly cofferdam weir body, lead to the unable balanced inboard effort in the cofferdam weir body 3 outside, there is the risk of empting. Therefore, the cofferdam outer side backfilling part 2 is arranged on the outer side of the steel sheet pile cofferdam, namely the cofferdam weir body 3, is used for backfilling the outer side of the cofferdam, plays a supporting role in the cofferdam weir body 3 and maintains the stability of the cofferdam weir body 3.

In some embodiments, the cofferdam body structure of the steel sheet pile cofferdam is formed by inserting and driving a plurality of steel sheet piles one by one, and in the inserting and driving process, the steel sheet piles need to be accurately positioned to ensure the tight mutual engagement between the steel sheet piles and the size of the cofferdam structure, so that the arrangement of the cofferdam positioning device 7 is particularly important. Although the conventional steel sheet pile cofferdam is also provided with the positioning guide device, the positioning guide device needs to be driven into the stratum near the cofferdam body of the steel sheet pile cofferdam for stable fixation, but the guide pile cannot sink due to the blocking effect of the floating pebbles in the pebble floating stratum, so the positioning guide device cannot be arranged in the pebble floating stratum. The cofferdam positioner 7 of this application is fixed firm with leading truck stand 71 buries in pile foundation 11. The positioning guide device is used for positioning guide when inserting and driving cofferdam steel sheet piles, and can adopt section steel or steel pipes, a guide frame upright post 71 is embedded when pouring concrete of a pile foundation 11, the upright post is embedded in a pile top super-pouring part and cannot be embedded below a pile head, so that the quality of the pile foundation 11 is influenced when the upright post is detached. Meanwhile, the vertical degree, elevation and plane position of the upright columns need to be strictly controlled, and the upright columns on the same surface are ensured to be on the same straight line in the transverse direction and the longitudinal direction.

Interior wailing 6 is used for interior support 10 of cofferdam weir body 3, plays the supporting role to cofferdam weir body 3, can specifically set up many interior wailings 6 according to the firm degree of cofferdam weir body 3 in order to promote cofferdam weir body 3.

Optionally, a cofferdam positioning device 7 is further included;

referring to fig. 2, 3 and 4, the cofferdam positioning device 7 is arranged at the outer side edge of the cofferdam body 3, and the external side backfilling part 2 of the cofferdam is used for filling the interval area between the cofferdam placing foundation pit 1 and the cofferdam positioning device 7.

In this embodiment, the cofferdam positioning device 7 includes a guide frame upright 71, a guide frame transverse bridge-direction support 72, and a guide frame longitudinal bridge-direction support 73, wherein the guide frame upright 71 is embedded in the super-grouting dummy pile portion of the pile foundation 11. When the concrete of the pile foundation 11 is poured, the upright 71 of the guide frame is embedded, and the upright is embedded in the over-poured part of the pile top and can not be embedded below the pile head, so that the quality of the pile foundation 11 is not influenced when the pile foundation is dismantled. Meanwhile, the vertical degree, elevation and plane position of the upright columns need to be strictly controlled, and the upright columns on the same surface are ensured to be on the same straight line in the transverse direction and the longitudinal direction. The pile foundation 11 and the pile top described in the present application refer to the base and the top of the steel sheet pile, that is, the base and the top of the cofferdam body 3. The pile head is the upper end part of the cofferdam weir body 3.

In some embodiments, referring to fig. 2, the cofferdam positioning device further comprises a bearing platform 12, which refers to a reinforced concrete platform arranged on top of the pile foundation to join the tops of the piles in order to bear and distribute the load transmitted by the pier shaft. The arrangement of the bearing platform 12 is beneficial to offset the extrusion force outside the cofferdam weir body 3, so as to maintain the stability of the cofferdam weir body 3.

In some embodiments, the material of the vertical column 71 of the guide frame can be selected from i-steel, the material of the transverse bridging support 72 of the guide frame can be selected from steel pipes, and the material of the longitudinal bridging support 73 of the guide frame can be selected from steel pipes, which are common materials in construction sites and are convenient for local materials.

Optionally, an entrance and exit hole 8 is also included;

referring to fig. 5, the man-in-and-out hole 8 is arranged on the cofferdam body 3, the lower part of the man-in-and-out hole 8 is composed of short steel sheet piles of the cofferdam body 3, and the upper part of the man-in-and-out hole 8 is composed of movable steel sheet piles;

the movable steel sheet pile is arranged at the top end of the upper part of the short steel sheet pile in a low water level period to form a man-in-and-out hole 8;

the movable steel sheet pile is arranged at the upper end of the short steel sheet pile in a high water level period and is in butt joint with the short steel sheet pile to seal the man-hole 8.

In some embodiments, the cofferdam weir body 3 is formed by inserting and driving steel sheet piles, and for the condition that relatively long steel sheet piles are exposed higher and people and materials are inconvenient to enter and exit, two short steel sheet piles can be combined into a whole pile, the steel sheet pile 82 at the lower part of the man hole is directly inserted and driven to the bottom, the steel sheet pile 81 at the upper part of the man hole is exposed partially, the upper pile and the lower pile leave the man hole 8 with a preset height of 2m, and the steel sheet pile 81 at the upper part of the man hole is pressed down to be butted with the steel sheet pile 82 at the lower part of the man hole before water rises so as to seal the man hole 8. Not only facilitating the access of personnel and material, but also preventing water from entering the cofferdam body 3.

Optionally, the steel bar fixing device further comprises a Z-shaped fixing steel bar 9;

referring to fig. 6A and 6B, the Z-shaped fixed steel bar 9 is arranged between the external wailing 5 and the internal wailing 6, and is used for fixedly connecting the external wailing 5 and the internal wailing 6;

one end of the Z-shaped fixed steel bar 9 is provided with a hook which is hooked on the lower edge of the inner wailing 6, and the other end of the Z-shaped fixed steel bar 9 is provided with a hook which is hooked on the outer wailing 5.

In some embodiments, Z-shaped fixation bars 9 fixedly connect the outer periphery jail with the inner periphery jail; in the method, for example, phi 22mm steel bars can be adopted as the Z-shaped fixed steel bars 9, the fixed interval is 1.5m, the Z-shaped fixed steel bars 9 are detached one by one along with the inserting and beating process of steel sheet piles, and wails 5 are fixed on the cofferdam body 3 through steel plates.

In other embodiments, a fixed gap needs to be left between the outer wailing 5 and the inner wall jail to facilitate installation of the steel sheet pile, so that the steel sheet pile can be inserted and driven down, and the gap cannot be too large, so that the steel sheet pile is inclined or positioned inaccurately. Therefore, movable Z-shaped fixed steel bars 9 are arranged between outer wales 5 and inner wales jail for fixed connection, Z-shaped fixed steel bars 9 are selected from steel bars with the diameter of 22mm in some embodiments, the fixed distance is 1.5m, one end of Z-shaped fixed steel bars 9 is provided with a hook at the inner lower edge of each outer wale 6, and the other end of each Z-shaped fixed steel bar 9 is provided with a hook at the outer wale 5, so that the outer wales 5 are fixed on the inner wales 6. Between outer wailing 5 and inner wailing jail 6, Z-shaped fixed steel bars 9 such as steel bars with the diameter of 22mm are fixedly connected according to the interval of 1.5m, the Z-shaped fixed steel bars 9 are detached one by one along with the inserting and driving of the steel sheet pile, and the outer wailing 5 is fixed to the steel sheet pile through steel plates.

Optionally, an inner support 10;

two ends of the inner support 10 are respectively and oppositely fixedly arranged on the inner wailing 6.

Because outside cofferdam outside backfill portion 2 causes certain extrusion force or holding power to cofferdam weir body 3, lead to cofferdam weir body 3 to have the risk of toppling over inwards, consequently, set up interior support 10 on the inside subtend inner wall jail of cofferdam weir body 3, has dredged the extrusion force to cofferdam weir body 3 effectively, has maintained cofferdam weir body 3's stable in structure, is favorable to further promoting the steadiness of boulder stratum cofferdam device.

With reference to fig. 7, in order to facilitate understanding of the second aspect of the present application, a pebble bed cofferdam construction method is provided, which is based on the pebble bed cofferdam apparatus described above, and includes the following steps:

s101, sloping, water falling, sloping and cofferdam foundation pit excavation are carried out to the edge of the bottom of the preset concrete of the cofferdam back cover 4;

s102, arranging a cofferdam placing base groove 1 for blocking a boulder stratum at the edge part;

s103, inserting and driving steel sheet piles to form a cofferdam weir body 3, fixedly installing outer wails 5 and inner wails jail on the outer side and the inner side of the cofferdam weir body 3, and installing the cofferdam weir body 3 on the edge of the bottom of preset concrete;

s104, pouring concrete at the bottom of the cofferdam body 3 to form a cofferdam back cover 4;

and S105, backfilling a foundation pit in the interval area between the cofferdam body 3 and the cofferdam placing foundation trench 1 to form a backfilling part 2 at the outer side of the cofferdam.

In some embodiments, the guide frame columns 71 may be embedded during the pouring of concrete of the pile foundation 11, and the guide frame columns 71 may be embedded in the portion of the pile top that is over-poured and may not be embedded below the pile head, so as to affect the quality of the pile foundation 11 during removal. Meanwhile, the vertical degree, elevation and plane position of the upright columns need to be strictly controlled, and the upright columns on the same surface are ensured to be on the same straight line in the transverse direction and the longitudinal direction.

In other embodiments, in step S102, a cofferdam foundation pit is excavated to the concrete bottom of the cofferdam back cover 4. And (3) adopting a digging machine to place a slope to excavate the cofferdam foundation pit, excavating according to an excavation mode of firstly excavating the center and then excavating the periphery, and excavating the position far away from the pile foundation 11 firstly and then excavating the periphery of the pile foundation 11. The excavator adopts a high-power excavator to ensure that the large boulder soil can be excavated. The boulders which are difficult to dig out can be matched with a breaking hammer to break and decompose underwater, and if the water is deep, a high-power water pump can be arranged to pump water. The depth of the foundation pit must be enough to be excavated, and the excavation depth is measured by the full coverage of the measuring rope, so that the thickness of the bottom sealing concrete must meet the requirement. The steel sheet pile position must be dug out to ensure that the steel sheet pile can reach the expected pile bottom elevation. The periphery of the pile foundation 11 must be dug out completely to ensure that the bottom sealing concrete is contacted with the pile Zhou Lianghao, so that water seepage is prevented, and safety is ensured. The excavated soil and stones are timely transported to the outside of the foundation pit, and are strictly forbidden to be stacked at the periphery of the foundation pit, so that the periphery of the foundation pit collapses. Because the foundation ditch is the boulder soil rock stratum all around, and the infiltration condition is outstanding in addition, causes the foundation ditch collapse all around easily, consequently, needs to increase resource allocation and accomplishes the foundation ditch excavation fast, prevents that the construction time is longer, and the foundation ditch collapses all around. If the periphery of the foundation pit collapses greatly, the slope protection can be backfilled by large-particle-size stone blocks at the periphery of the foundation pit.

In some embodiments, in step S103, in the process of installing wails 5, channel steel is used for the periphery jail, a notch of the channel steel faces downward, the height of wails 5 is equal to the inner periphery jail of the guide frame, the buckling width of the steel sheet pile is d, and the distance between wails 5 is 5mm and is 5mm, that is, d +5 mm. And after the steel sheet pile is inserted and beaten, wailing 5 is fixed on the steel sheet pile by using a steel plate. Outer wailing 5 channel steel is fixed with an inner wall jail, and the distance between the inner wailing 5 and the outer wailing 5 is controlled, so that the outer wailing 5 can tightly hoop a steel sheet pile, the steel sheet pile is prevented from toppling outwards, and the steel sheet pile is ensured to be vertical.

In some embodiments, the method further comprises a step of cleaning inside the cofferdam, in order to ensure that the thickness of the bottom sealing concrete, namely the thickness of the bottom sealing 4 of the cofferdam meets the requirement, the settled sandstone is cleaned inside the cofferdam by adopting a gas lift method after the cofferdam is closed, the settled sandstone inside the cofferdam is blown out of the cofferdam by high-pressure compressed air, and the bottom sealing concrete is poured immediately after the sand is cleaned.

In other embodiments, during the construction of the cofferdam back cover 4, during the pouring of the underwater back cover concrete, care should be taken to ensure that the back cover concrete around the pile foundation 11 and on the inner wall of the steel sheet pile are in good contact with each other to prevent water seepage. The elevation of the concrete surface is measured in the process, and neither over-irrigation nor under-irrigation is achieved.

In some embodiments, when the foundation pit outside the steel sheet pile cofferdam is backfilled, namely the construction of the backfilling part 2 outside the cofferdam, the foundation pit outside the steel sheet pile is backfilled by fine-grained sand gravel, and the large boulder is strictly forbidden to be filled, so that the steel sheet pile can be smoothly dismantled. Meanwhile, the backfill soil is compacted as much as possible, and the steel sheet pile is not required to be extruded, so that the steel sheet pile is prevented from deforming. The outside of the steel sheet pile facing the water is frequently checked to be scoured, so that the river is prevented from scouring and hollowing the soil layer, and the outside of the steel sheet pile loses support. After the foundation pit on the outer side of the steel sheet pile is backfilled, wails 5 outside the steel sheet pile cofferdam can be removed.

Optionally, after the step of providing the cofferdam foundation pit 1 for blocking the pebble formation at the edge, the method further includes:

and arranging a cofferdam positioning device 7, inserting and driving steel sheet piles along the cofferdam positioning device 7 to form a cofferdam body 3, and backfilling a foundation pit in an interval area between the cofferdam positioning device 7 and the cofferdam placing foundation trench 1 to form a cofferdam outer side backfilling part 2.

In some embodiments, the cofferdam positioning device 7 may use the inner periphery jail of the lowest layer as a guiding frame, so the guiding frame geometry, plane position, elevation must meet the requirements, and the guiding frame needs to be installed horizontally. The guide frame is processed in the back field and is installed by a crane or a crawler crane.

Optionally, inserting and beating the steel sheet piles to form a cofferdam weir body 3, fixedly installing outer wails 5 and inner wails jail at the outer side and the inner side of the cofferdam weir body 3, and installing the cofferdam weir body 3 in the step of presetting the edge of the bottom of the concrete, further including:

an in-out man hole 8 is formed in the cofferdam weir body 3, the lower part of the in-out man hole 8 is composed of short steel sheet piles of the cofferdam weir body 3, and the upper part of the in-out man hole 8 is composed of movable steel sheet piles;

the movable steel sheet pile is arranged at the top end of the upper part of the short steel sheet pile in a low water level period to form a man-in-and-out hole 8;

the movable steel sheet pile is arranged at the upper end of the short steel sheet pile in a high water level period and is in butt joint with the short steel sheet pile to seal the access manhole 8.

Optionally, inserting and beating the steel sheet piles to form a cofferdam weir body 3, fixedly installing outer wails 5 and inner wails jail at the outer side and the inner side of the cofferdam weir body 3, and installing the cofferdam weir body 3 in the step of presetting the edge of the bottom of the concrete, further including:

z-shaped fixed steel bars 9 are arranged between the external wails 5 and the internal wails 6 and are used for fixedly connecting the external wails 5 and the internal wails 6;

one end of the Z-shaped fixed steel bar 9 is provided with a hook to be hooked on the lower edge of the inner side of the inner wail 6, and the other end of the Z-shaped fixed steel bar 9 is provided with a hook to be hooked on the outer wail 5.

Optionally, inserting and beating the steel sheet piles to form a cofferdam weir body 3, fixedly installing outer wails 5 and inner wails jail at the outer side and the inner side of the cofferdam weir body 3, and installing the cofferdam weir body 3 in the step of presetting the edge of the bottom of the concrete, further including:

inner supports 10 are fixedly arranged on the inner wails 6, and two ends of each inner support 10 are respectively and oppositely fixedly arranged on the inner wails 6.

According to the pebble floating stratum cofferdam device and the construction method thereof, when the cofferdam is constructed, the construction method of arranging foundation grooves on the cofferdam is adopted, the cofferdam can reach the installation position favorably, the problem that construction accidents are caused by easy cracking and collapse of the pebble floating stratum in construction is avoided, excavated earth and stones can be repeatedly utilized for backfilling after screening, and a good supporting effect is achieved. No matter the cofferdam adopts steel sheet pile or steel bushing box construction, all demonstrate better structural stability. The device has a simple structure, shortens the construction period, improves the construction efficiency to a certain extent, and has better economy; the cofferdam construction in the boulder stratum is facilitated, and the cofferdam construction method is suitable for popularization and application in the industry.

The embodiments provided in the present application are only a few examples of the general concept of the present application, and do not limit the scope of the present application. Any other embodiments extended according to the scheme of the present application without inventive efforts will be within the scope of protection of the present application for a person skilled in the art.

Claims (10)

1. A pebble stratum cofferdam device is characterized by comprising a cofferdam placing foundation trench, a cofferdam outer backfilling part, a cofferdam body, a cofferdam back cover, a periphery jail and inner wails;

the cofferdam placing foundation groove is used for floating a pebble stratum by Yu Zudang, and the pebble stratum is separated from the cofferdam body;

the outer side backfilling part of the cofferdam is used for filling a spacing area between the cofferdam placing foundation trench and the cofferdam body;

the cofferdam body is a steel sheet pile cofferdam;

the cofferdam back cover is arranged at the bottom of the inner side of the cofferdam body;

the outer wails are made of channel steel or profile steel, are arranged on the outer side face of the cofferdam weir body and are used for fixing the cofferdam weir body from the outer side;

the inner wailing is arranged on the inner side of the cofferdam weir body and used for the inner support of the cofferdam weir body.

2. The pebble formation cofferdam apparatus of claim 1 further comprising a cofferdam positioning means;

the cofferdam positioning device is arranged on the outer side edge of the cofferdam body, and the outer side backfilling part of the cofferdam is used for filling a spacing area between the cofferdam placing foundation trench and the cofferdam positioning device.

3. The pebble formation cofferdam apparatus of claim 1 further comprising an access man hole;

the man-in-and-out hole is formed in the cofferdam weir body, the lower part of the man-in-and-out hole is composed of short steel sheet piles of the cofferdam weir body, and the upper part of the man-in-and-out hole is composed of movable steel sheet piles;

the movable steel sheet pile is arranged at the top end of the upper part of the short steel sheet pile in a low water level period to form a man-in-and-out hole;

the movable steel sheet pile is arranged at the upper end of the short steel sheet pile in a high water level period and is in butt joint with the short steel sheet pile to seal the man-hole.

4. The pebble formation cofferdam apparatus of claim 1, further comprising Z-shaped fixing steel bars;

the Z-shaped fixed steel bar is arranged between the outer wailing and the inner wailing and is used for fixedly connecting the outer wailing and the inner wailing;

one end of the Z-shaped fixed steel bar is provided with a hook which is hooked at the lower edge of the inner side of the inner periphery jail, and the other end of the Z-shaped fixed steel bar is provided with a hook which is hooked on the outer periphery wailing.

5. The boulder bed cofferdam apparatus of claim 1, further comprising an inner support;

two ends of the inner support are respectively and oppositely fixedly arranged on the inner wailing.

6. A pebble-floated stratum cofferdam construction method based on the pebble-floated stratum cofferdam device of claims 1-5, characterized by comprising the following steps:

carrying out slope lowering, water lowering and slope digging on a cofferdam foundation pit to reach the edge of the bottom of the preset concrete at the bottom sealing of the cofferdam;

arranging cofferdam placing foundation grooves for blocking the boulder stratum at the edge part;

inserting and beating steel sheet piles to form a cofferdam weir body, fixedly installing outer wails and inner wails jail on the outer side and the inner side of the cofferdam weir body, and installing the cofferdam weir body at the edge of the bottom of preset concrete;

pouring concrete at the bottom of the cofferdam body to form a cofferdam back cover;

and backfilling a foundation pit in the interval area between the cofferdam body and the cofferdam placing foundation trench to form a backfilling part at the outer side of the cofferdam.

7. The pebble floating stratum cofferdam construction method of claim 6, wherein after said step of setting a cofferdam installation foundation groove for blocking the pebble floating stratum at the edge, further comprising:

and (2) arranging a cofferdam positioning device, inserting and driving steel sheet piles along the cofferdam positioning device to form a cofferdam body, and backfilling a foundation pit in a spacing area between the cofferdam positioning device and the cofferdam placing foundation trench to form a backfilling part at the outer side of the cofferdam.

8. The floating pebble formation cofferdam construction method of claim 6, wherein the inserting and beating steel sheet piles form a cofferdam weir body, an outer wail and an inner wail jail are fixedly installed at the outer side and the inner side of the cofferdam weir body, and the cofferdam weir body is installed in the step of presetting the concrete bottom edge, further comprising:

an in-out man hole is formed in the cofferdam weir body, the lower part of the in-out man hole consists of short steel sheet piles of the cofferdam weir body, and the upper part of the in-out man hole consists of movable steel sheet piles;

the movable steel sheet pile is arranged at the top end of the upper part of the short steel sheet pile in a low water level period to form a man-in-and-out hole;

the movable steel sheet pile is arranged at the upper end of the short steel sheet pile in a high water level period and is in butt joint with the short steel sheet pile to seal the man-hole.

9. The cofferdam construction method of the boulder bed as claimed in claim 6, wherein the inserting and beating steel sheet piles form a cofferdam weir body, outer wails and inner wails jail are fixedly installed at the outer side and the inner side of the cofferdam weir body, and the cofferdam weir body is installed at the step of presetting the bottom edge of concrete, and further comprising:

z-shaped fixed steel bars are arranged between the outer wails and the inner wails and are used for fixedly connecting the outer wails and the inner wails;

one end of the Z-shaped fixed steel bar is provided with a hook which is hooked at the lower edge of the inner side of the inner periphery jail, and the other end of the Z-shaped fixed steel bar is provided with a hook which is hooked on the outer periphery wailing.

10. The floating pebble formation cofferdam construction method of claim 6, wherein the inserting and beating steel sheet piles form a cofferdam weir body, an outer wail and an inner wail jail are fixedly installed at the outer side and the inner side of the cofferdam weir body, and the cofferdam weir body is installed in the step of presetting the concrete bottom edge, further comprising:

an inner support is fixedly arranged on the inner wailing, and two ends of the inner support are respectively and oppositely and fixedly arranged on the inner wailing.

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