Construction method of combined steel sheet pile cofferdam for deep foundation pit of river block pier cap

Abstract

The application discloses a kind of river section deep foundation pit combined steel sheet pile cofferdam construction methods, it is related to cofferdam construction technical field, with the advantage that the distance between adjacent bearing platform is small, steel sheet pile can still be constructed, its technical scheme key points are: to pier bearing platform is marked and after rechecking is correct, simultaneously, the position of 1 meter-1.1 meter outside the line of bearing platform foundation is released steel sheet pile insertion position, steel sheet pile is directly inserted, and the line of steel sheet pile is lofted before insertion, under the premise of vertical steel sheet pile, steel sheet pile is inserted into, to pier bearing platform is marked classification: one bearing platform combination, two bearing platform combination, three bearing platform combination ……N bearing platform combination, the outer frame of combination: the position of 1 meter-1.1 meter outside the line of adjacent bearing platform foundation is not interfered with portion respectively along 1 meter-1.1 meter outside the line of each bearing platform foundation, steel sheet pile is set up, and the latter of interfered portion is excavated together and connected in same combination foundation pit.

Description

TECHNICAL FIELD

[0001] The present application relates to the cofferdam construction technical field, specifically to a kind of river section pile cap deep foundation pit combined steel sheet pile cofferdam construction method. BACKGROUND

[0002] In the construction of city viaduct pile cap deep foundation pit across river section, steel sheet pile cofferdam, as a temporary water retaining structure, provides a water-free construction environment for the lower structure, and is a commonly used foundation pit support method. Steel sheet pile cofferdam has the advantages of high strength, good toughness, good waterproof performance, stable and safe support, high recycling rate, etc.

[0003] After the cofferdam is pumped out and the old bridge is demolished, the silt at the bottom of the river is treated by lime soil replacement, and the site is compacted. The water pile cap is converted into a land pile cap for construction.

[0004] The pile cap is located at the top of the pile foundation and is a force transmission platform between the pile and the pier column or pier body. It connects multiple piles into a whole to form a pile foundation. The pile cap uniformly distributes the load from the pier body or column to each pile top, avoiding single pile overload, and simultaneously transmits the load to the deep foundation to reduce the risk of settlement. Each pile cap is surrounded by steel sheet piles before construction.

[0005] However, due to the size limitation of the site, the distance between adjacent pile caps is small, and steel sheet piles cannot be constructed.

[0006] Therefore, the applicant has developed a new technical solution to solve the above technical problems. SUMMARY

[0007] To solve the above technical problems, the present application adopts the following technical solution:

[0008] To solve the above technical problems, the present application adopts the following technical solution:

[0009] The present application provides a kind of river section pile cap deep foundation pit combined steel sheet pile cofferdam construction method, including the following processes:

[0010] Steel sheet pile positioning → steel sheet pile setting → initial excavation → steel enclosing purlin installation → steel support plate installation → secondary excavation → cushion construction → pile cap construction → backfilling after completion → removal of steel support plate and steel enclosing purlin → removal of steel sheet pile;

[0011] Steel sheet pile positioning and driving: after the pier position and the bearing platform are marked and no error is found, the steel sheet pile driving position is placed 1-1.1 meters outside the bearing platform foundation line, the steel sheet pile is directly driven, the steel sheet pile line is laid out before driving, and the steel sheet pile is driven into the steel sheet pile under the premise of verticality;

[0012] Marking the classification of the pier position and the bearing platform: one bearing platform combination, two bearing platform combinations, three bearing platform combinations, and N bearing platform combinations; the outer frame of the combination: the part without interference along the respective bearing platform foundation line outside 1-1.1 meters is driven by the steel sheet pile, and the part with interference is excavated together and connected in the same combined foundation pit.

[0013] By adopting the above technical scheme, the part without interference along the respective bearing platform foundation line outside 1-1.1 meters is driven by the steel sheet pile, and the part with interference is excavated together and connected in the same combined foundation pit, so that there is one bearing platform or two or three in the same combined foundation pit, thereby reducing the limitation of the size of the site, and enabling the steel sheet pile to be constructed even when the distance between the adjacent bearing platforms is small.

[0014] Preferably, the excavation of the earthwork is vertically divided into two layers from top to bottom, i.e. initial excavation: the first layer of soil is excavated to a position 0.5 m below the steel support plate, an ordinary excavator is used for excavation, and the earthwork is directly transported outside by a transport vehicle; after the first layer of soil is excavated, steel enclosing purlins and steel support plates are constructed, and after the steel support plate construction is completed, a long-arm excavator is used for second-layer soil excavation, i.e. secondary excavation, after excavation to the pit bottom elevation, concrete cushion pouring is immediately performed, and after the concrete strength of the concrete cushion reaches the requirement, subsequent pile head removal and bearing platform construction can be performed.

[0015] Preferably, the steel enclosing purlins and the steel support plates are installed: the steel enclosing purlin bottom elevation position is measured on the exposed steel sheet pile of the initial excavation, and a bracket is welded; the steel enclosing purlin is hoisted onto the bracket and welded, at this time, the steel enclosing purlin is distributed around the inner wall of the steel sheet pile, steel support plates are installed between adjacent and perpendicular steel enclosing purlins, and the two ends of the steel support plate are welded to the steel enclosing purlin.

[0016] Preferably, the bearing platform construction includes bearing platform reinforcement binding on the concrete cushion, pre-connecting the pier reinforcement and the bearing platform reinforcement, and then supporting the formwork connected with each other around the bearing platform reinforcement and pouring the bearing platform.

[0017] Preferably, the template comprises a steel plate on the side of the pile cap reinforcement and a plurality of vertically distributed vertical plates on the side of the steel plate away from the pile cap reinforcement, the upper end of the vertical plate extends beyond the upper end of the steel plate, the vertical column on the opposite two steel plates is connected by the tensioning reinforcement, the adjacent two steel plates are connected by the angle steel, the angle steel is distributed along the height direction of the steel plate, and is connected with the side of each steel plate by the bolt.

[0018] Preferably, when the position of the steel sheet pile on one side of the pile cap is less than 1 meter from the outer side of the pile cap foundation line and less than the thickness of the steel sheet plus the vertical plate, the template at this position is replaced by the following structure: a plurality of closely fitted foam boards between the steel sheet pile and the pile cap reinforcement, each foam board is vertically distributed and arranged along the length direction of the pile cap, one side of each foam board is in contact with the steel sheet pile, and the other side is in contact with the steel plate on the adjacent template.

[0019] Preferably, each vertical plate comprises two mounting plates connected with the plate surface of the steel plate and having a U-shaped cross section, the U-shaped openings of the two mounting plates are distributed away from each other, and one of the opposite vertical sides of the mounting plate is detachably connected with the steel plate by the screw, and there is a gap between the two mounting plates of each vertical plate for the tensioning reinforcement to pass through.

[0020] And each of the two mounting plates is provided with an adjusting member for adjusting the position of the tensioning reinforcement.

[0021] Preferably, the adjusting member comprises a horizontal plate placed on the vertical side wall of each of the two mounting plates, the horizontal plate is above the steel plate and is used to support the tensioning reinforcement, a pressing plate is placed on the vertical side wall of each of the two mounting plates, the pressing plate and the horizontal plate are respectively located on the two sides of the opposite vertical side walls of the mounting plate, and a prism is provided on the side of the horizontal plate facing the pressing plate, a threaded rod is coaxially provided on the prism, a through hole is formed in the pressing plate for the threaded rod to pass through, the threaded rod is threadedly connected with a locking block in contact with the pressing plate after passing through the pressing plate, and a putting slot is formed in the upper end surface of the pressing plate for the tensioning reinforcement to be put in, when the tensioning reinforcement has not been straightened and put into the putting slot, the tensioning reinforcement is in contact with the upper end surface of the horizontal plate, the two end outer walls of the tensioning reinforcement are provided with threads, and a screwing block is threadedly connected with the pressing plate away from the horizontal plate.

[0022] Preferably, the vertical plate provided with the contact rod has one mounting plate, and the height of the foam board is greater than the height of the pile cap, the side of the foam board facing the steel sheet pile is provided with a plurality of vertically inserted vertical plates, the side edges of the two vertical plates farthest apart are provided with extension plates extending in the direction of the template, one end of the steel plate of the adjacent template extends into the extension plate, and the plate surface of the steel plate is in contact with one side of the foam board.

[0023] Preferably, the steel enclosing purlin and steel support plate are removed symmetrically and at intervals to reduce the local deformation and cracking caused by excessive instantaneous pre-stress release.

[0024] When the steel enclosing purlins are close to each other in the same combined foundation pit, thick steel pads in the shape of a triangle are welded between them.

[0025] The beneficial effects of the present application are that the positions 1-1.1 meters outside the edge lines of adjacent pile caps are not disturbed, and steel sheet piles are arranged along the positions 1-1.1 meters outside the edge lines of the respective pile caps, and the disturbed parts are excavated together to be connected in the same combined foundation pit, so that there is one pile cap or two or three pile caps in the same combined foundation pit, thereby reducing the limitation of the size of the site, and enabling the adjacent pile caps to be constructed with steel sheet piles even when the distance between the adjacent pile caps is small. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or the prior art description. Obviously, the drawings in the following description only constitute some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0027] Figure 1 It is a structural schematic diagram of the present embodiment;

[0028] Figure 2 It is a structural schematic diagram of the present embodiment for embodying double-row water-stop steel sheet piles;

[0029] Figure 3 It is a structural schematic diagram of the present embodiment for embodying a combined foundation pit of one pile cap combination;

[0030] Figure 4 It is a structural schematic diagram of the present embodiment for embodying a combined foundation pit of two pile cap combinations; Figure 5 It is a structural schematic diagram of the present embodiment for embodying a combined foundation pit of two pile cap combinations;

[0031] Figure 6 It is a structural schematic diagram of the present embodiment for embodying a combined foundation pit of three pile cap combinations;

[0032] Figure 7 It is a structural schematic diagram of the present embodiment for embodying a combined foundation pit of three pile cap combinations;

[0033] Figure 8 It is a structural schematic diagram of the present embodiment for embodying a combined foundation pit of three pile cap combinations; Figure 7 It is an enlarged structural schematic diagram of part A in FIG. 7;

[0034] Figure 9 It is an enlarged structural schematic diagram of part A in FIG. 7; Figure 7Enlarged structural schematic view of the middle B part;

[0035] Figure 10 Structural schematic view for embodying the adjusting member of the present embodiment;

[0036] Figure 11 Structural schematic view for embodying the threaded rod of the present embodiment;

[0037] Figure 12 Structural schematic view for embodying the foam board of the present embodiment;

[0038] Figure 13 Structural schematic view for embodying the longitudinal section of the cofferdam of the present embodiment.

[0039] Explanation of reference numerals:

[0040] In the figure: 1, steel sheet pile; 11, pile cap; 111, cushion layer; 12, steel encasing purlin; 121, thick steel cushion plate; 13, same group of combined foundation pit; 14, steel support plate; 15, pier body; 16, steel sheet; 161, opposite-pulling steel bar; 162, angle steel; 163, abutting bar; 164, mounting plate; 17, foam board; 18, cross plate; 181, compression plate; 182, prism; 183, threaded rod; 184, locking block; 185, slot; 186, screwing block; 19, vertical plate; 191, extension plate; 2, double-row water-stopping steel sheet pile; 21, steel temporary bridge. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0042] As Figure 2 , the following construction is the construction of the present applicant in the Jinxi Bridge old bridge demolition and reconstruction project, which is the construction of the south and north side steel sheet pile cofferdams of the Jinxi Bridge old bridge before the old bridge is demolished, the treatment of the silt at the bottom of the river by lime soil replacement after the cofferdams are pumped and the old bridge is demolished, the field elevation after compaction is 2.0 m, the conversion of the water-borne pile cap into a land-borne pile cap, and the construction of the new bridge. After the old bridge of the Jinxi Bridge is demolished, a new elevated bridge is built over the river section, and then the ground bridge is reconstructed. It is planned to construct the lower structures of the two bridges together, so the pile caps in the lower river are dense, the number is large, the spacing is small, and two bridges are involved.

[0043] The double-row water-stopping steel sheet piles 2 are located outside the scope of the newly-built Jinxi Bridge. The double-row water-stopping steel sheet piles 2 are of the Larsen IV type, with a pile length of 12 m and a distance between the two rows of 1 m. The distance between the double-row water-stopping steel sheet piles 2 and the two side steel bridges is 2 m. The normal water level of the river at the Jinxi Bridge is 2.0 m, the bottom of the riverbed is -1.9 m, and the water depth is 3.9 m. The design top of the double-row water-stopping steel sheet piles 2 is 3.0 m, and the bottom is -9.0 m. According to the survey report, the thickness of the silt layer is 1.0-1.4 m, and the effective depth of the double-row water-stopping steel sheet piles into the soil is 5.7-6.1 m. The double-row water-stopping steel sheet piles 2 in the above process are mainly used to block the water flow under the old bridge, facilitating the subsequent construction of the pile cap;

[0044] In addition, a steel bridge 21 can be laid in the double-row water-stopping steel sheet piles on the south and north sides to facilitate the normal passage of social vehicles and pedestrians.

[0045] A construction method of a combined steel sheet pile cofferdam for a river block section pile cap deep foundation pit, such as Figure 1 and Figure 3 , comprises the following processes:

[0046] Steel sheet pile positioning → steel sheet pile setting → initial excavation → steel enclosing purlin installation → steel support plate installation → secondary excavation → cushion construction → pile cap construction → backfilling after completion → removal of steel support plate and steel enclosing purlin → removal of steel sheet pile; the method is a method for non-flood season construction.

[0047] Steel sheet pile 1 positioning and steel sheet pile 1 setting: after the pier position pile cap 11 is marked and verified to be correct, the steel sheet pile 1 insertion and setting position is placed 1-1.1 m away from the outer side of the pile cap 11 foundation line. The steel sheet pile 1 is directly inserted and set. Before insertion and setting, the steel sheet pile 1 line is laid out. The steel sheet pile 1 is inserted and set vertically;

[0048] such as Figure 3 and Figure 4 and Figure 5 and Figure 6 , the pier position pile cap 11 is marked and classified: one pile cap 11 combination, two pile cap 11 combinations, three pile cap 11 combinations, …, N pile cap 11 combinations. The outer frame of the combination: the part without interference 1-1.1 m away from the outer side of the adjacent pile cap 11 foundation line is set with steel sheet piles 1 along the outer side of the respective pile cap 11 foundation line. The part with interference is excavated together later and connected in the same combined foundation pit 13;

[0049] The part without interference refers to the position 1-1.1 m away from the outer side of the pile cap 11 foundation line, which does not interfere with the position 1-1.1 m away from the outer side of the adjacent pile cap 11 foundation line;

[0050] The disturbed part refers to the position 1m-1.1m outside the foundation edge line of the bearing platform 11 which will form disturbance with the position 1m-1.1m outside the foundation edge line of the adjacent bearing platform 11, and the disturbed part is excavated through at the position of disturbance;

[0051] The same combined foundation pit 13 is a closed loop formed by the steel sheet pile, i.e. a bearing platform cofferdam, for example, when one bearing platform 11 is combined, the same combined foundation pit 13 is in the shape of a rectangle, when two bearing platforms 11 are combined, the same combined foundation pit 13 is in the shape of Z or a rectangle, etc.

[0052] As Figure 3 and Figure 4 and Figure 5 and Figure 6 The position 1m-1.1m outside the foundation edge line of the adjacent bearing platform 11 without disturbance is provided with a steel sheet pile 1 along the position 1m-1.1m outside the foundation edge line of the respective bearing platform 11, and the disturbed part is excavated through together behind the position of disturbance in the same combined foundation pit 13, so that there is one bearing platform 11 or two or three bearing platforms 11 in the same combined foundation pit 13, thereby reducing the limitation of the size of the site, and enabling the distance between the adjacent bearing platforms 11 to be small and still enabling the steel sheet pile 1 to be constructed.

[0053] As Figure 3 and Figure 4 and Figure 5 and Figure 6 The vertical excavation of the earthwork is divided into two layers from top to bottom, i.e. initial excavation: the first layer of soil is excavated to a position 0.5m below the steel support plate 14, and a common excavator is used for excavation, and the earthwork is directly transported outside by a transport vehicle, and the common excavator is preferably far away from the foundation pit during construction to reduce the dynamic load at the edge of the foundation pit; after the first layer of soil is excavated, the steel enclosing purlin 12 and the steel support plate 14 are constructed, and after the steel support plate 14 is constructed, a long-arm excavator is used for the second layer of soil excavation, i.e. secondary excavation, and after the excavation reaches the bottom elevation of the pit, the concrete cushion layer 111 is immediately poured, and after the concrete strength of the concrete cushion layer 111 reaches the requirement, the subsequent pile head removal and bearing platform 11 construction can be performed; before pouring the concrete cushion layer 111, a plastic film is laid on the inner wall of the steel sheet pile 1, and then the concrete cushion layer 111 is poured, and at this time, the concrete is poured to fill the bottom of the foundation pit, and since there is a plastic film between the steel sheet pile 1 and the concrete, the subsequent pulling out of the steel sheet pile 1 is not affected, at this time, the cushion layer 111 is poured to fill the bottom of the foundation pit to achieve the purpose of sealing the bottom of the foundation pit, and facilitate the formation of the working surface for subsequent construction, in addition, the cushion layer 111 also supports the steel sheet pile 1 to increase the stability of the foundation pit enclosure.

[0054] The pile head chiseling is to chisel the pile head of the pile body which is previously driven into the ground and located below the pile cap 11, and the head of the pile body is located above the concrete cushion 111. The leaked steel bars are located in the pile cap 11 after the concrete is chiseled. According to the implementation scheme of the project, the 15m deep Larssen IV steel sheet pile 1 is used for support, and the 400*400 H-shaped steel is used as the steel enclosing purlin 12 and the steel support plate 14.

[0055] As Figure 3 and Figure 4 and Figure 5 and Figure 6 The steel enclosing purlin 12 and the steel support plate 14 are installed: the bottom elevation position of the steel enclosing purlin 12 is measured and marked on the exposed steel sheet pile 1 after the initial excavation, and the bracket is welded; the steel enclosing purlin 12 is hoisted and placed on the bracket, and spot welding is performed. At this time, the steel enclosing purlin 12 is distributed around the inner wall of the steel sheet pile 1 in a circumferential direction and is closed in a ring, that is, the steel enclosing purlin 12 is distributed around the same combined foundation pit 13 edge, and the steel support plate 14 is additionally installed between the adjacent and perpendicular steel enclosing purlins 12, or the steel support plate 14 can be additionally installed between the steel enclosing purlins 12 which are close to each other and parallel to each other, thereby increasing the support force of the steel enclosing purlin 12 and the steel support plate 14 on the steel sheet pile 1. The two ends of the steel support plate 14 are respectively spot welded on the steel enclosing purlin 12. The design purpose of spot welding is to facilitate the separation of the welding points by using existing technologies such as heat cutting method and chemical removal method in the later stage, and to facilitate the removal of the steel enclosing purlin 12 and the steel support plate 14.

[0056] The sizes in the above construction include but are not limited to the following examples: as Figure 13 The site elevation at the pier cap is 2.0m, the design bottom elevation of the pile cap 11 is -4.641~ -3.817m, and the top elevation is -2.141~ -0.817m. The scheme is arranged to drive the 15m long Larssen IV water stop steel sheet pile 1 (top elevation 2.3m, bottom elevation -12.7m) at 1m~1.1m outside the foundation line of the pile cap 11, vertically set 1 row of steel enclosing purlins 12 and steel support plates 14, and the steel enclosing purlins 12 and the steel support plates 14 are both made of 400*400 H-shaped steel and are set at 1.80m below the top of the steel sheet pile 1. A 15cm thick C15 concrete cushion is arranged at the bottom of the pile cap. The long-arm excavator is used for soil removal, and the excavation depth is 5.967~6.791m.

[0057] As Figure 3 and Figure 4 and Figure 5 and Figure 6 The construction of the pile cap 11 includes the following steps: the reinforcement of the pile cap 11 is bound on the concrete cushion 111, the reinforcement of the pier body 15 is then pre-connected with the reinforcement of the pile cap 11, that is, the step of pre-burying the reinforcement of the pier body 15 is implemented, and the formwork connected with each other is arranged around the reinforcement of the pile cap 11, and the pile cap 11 is poured.

[0058] As Figure 7 and Figure 8 andFigure 9 When the bearing platform 11 is rectangular, the steel plates 16 around the bearing platform 11 are in the shape of a rectangle, the upper ends of the vertical plates extend beyond the upper ends of the steel plates 16, the vertical columns on the opposite two steel plates 16 are connected by the tensioning steel bars 161, the purpose is to provide stable tension to the opposite two forms, at this time, the vertical columns on the opposite two steel plates 16 are all provided with the tensioning steel bars 161, so that the tensioning steel bars 161 are distributed in two layers above the bearing platform 11, for example, the lower layer is the longitudinal tensioning steel bars 161 and the upper layer is the transverse tensioning steel bars 161, the adjacent two steel plates 16 are connected by the angle steels 162, the angle steels 162 are distributed along the height direction of the steel plates 16 and are connected to the side surfaces of the steel plates 16 by bolts, so as to fix the steel plates 16 in the shape of a rectangle.

[0059] In addition, in order to increase the strength of the steel plates 16, horizontal ribs can also be arranged on the side of the steel plates 16 away from the bearing platform 11, the horizontal ribs are distributed along the length direction of the steel plates 16, and the vertical plates are arranged on the horizontal ribs.

[0060] As shown in Figure 12 When the steel sheet pile 1 on one side of the bearing platform 11 is punched at a position less than 1 meter from the outer side of the foundation line of the bearing platform 11 and less than the thickness of the steel plate 16 plus the vertical plate, the above situation exists because there may be deviation in punching, or there may be hard blocks in the riverbed, etc., and only avoidance is possible. The form at this position is replaced by the following structure: a plurality of foam boards 17 closely abutting each other are arranged between the steel sheet pile 1 and the steel bars of the bearing platform 11, each foam board 17 is vertically distributed and arranged along the length direction of the bearing platform 11, one side of each foam board 17 abuts against the steel sheet pile 1, and the other two end surfaces abut against the steel plates 16 on the adjacent forms, at this time, the steel plates 16 abut against the foam boards 17 on the steel sheet pile 1, the height of the foam boards 17 is greater than the height of the steel plates 16, and the vertical plates on the forms corresponding to the foam boards 17 are all provided with abutting rods 163 abutting against the side surfaces of the steel sheet pile 1, at this time, the abutting rods 163 provide support force to the forms connected to the abutting rods 163, so that the position of the form is stable during pouring of the bearing platform 11. The arrangement of the foam boards 17 facilitates the reuse of other forms after the pouring and forming of the bearing platform 11, and the foam boards 17 cannot be removed because they are located between the steel sheet pile 1 and the bearing platform 11, thereby forming a separation surface between the bearing platform 11 and the steel sheet pile 1, which facilitates the subsequent pulling out of the steel sheet pile 1.

[0061] As shown in Figure 8 and Figure 9, each vertical plate comprises two mounting plates 164 connected with the plate surface of the steel plate 16 and having a U-shaped cross section, the U-shaped openings of the two mounting plates 164 are distributed away from each other, i.e. the two opposite vertical sides of the mounting plate 164 are distributed away from the vertical sides on the other mounting plate 164 respectively, and one of the two opposite vertical sides of the mounting plate 164 is detachably connected with the steel plate 16 by a screw, at this time, the vertical sides of the two mounting plates 164 are in contact with the steel plate 16, and a gap exists between the two mounting plates 164 of each vertical plate and is used for passing the tendon 161; since the tendon 161 has two layers, the adjusting member is arranged on each two mounting plates 164.

[0062] As Figure 8 and Figure 9 and Figure 10 and Figure 11 , the adjusting member comprises a horizontal plate 18 arranged on the vertical side walls of each two mounting plates 164, the horizontal plate 18 is located above the steel plate 16 and is used for supporting the tendon 161, a pressing plate 181 is arranged on the vertical side walls of each two mounting plates 164, the pressing plate 181 and the horizontal plate 18 are located on the two sides of the two opposite vertical sides of the mounting plate 164 respectively, and the horizontal plate 18 is provided with a prism 182 on the side facing the pressing plate 181, the prism 182 is located in the gap between the two mounting plates 164, a threaded rod 183 is coaxially arranged on the prism 182, the pressing plate 181 is provided with a through hole for the threaded rod 183 to pass through, the threaded rod 183 is threadedly connected with a locking block 184 in contact with the pressing plate 181 after passing through the pressing plate 181, the upper end surface of the pressing plate 181 is provided with an insertion groove 185 for the tendon 161 to be inserted, the groove opening of the insertion groove 185 extends out of the upper end surface of the pressing plate 181, and the groove bottom is used for the tendon 161 to be inserted, when the tendon 161 has not been straightened and inserted into the insertion groove 185, the tendon 161 is in contact with the upper end surface of the horizontal plate 18, the two ends of the tendon 161 are provided with threads, and a screw block 186 located on the side of the pressing plate 181 away from the horizontal plate 18 is connected by the threads. The structure of the tendon 161 can be a round steel, and the two ends of the round steel in the length direction are welded with screws.

[0063] As Figure 8 and Figure 9 and Figure 10 and Figure 11, the adjusting piece working process: after the bearing platform 11 template is installed, the first step is to install the horizontal plate 18 and the compression plate 181 from top to bottom in the two installation plates 164, at this time, the horizontal plate 18 and the compression plate 181 are located on the two opposite vertical sides of the two installation plates 164, the horizontal plate 18 is above the steel plate 16, which is convenient for supporting the subsequent pull steel 161, the prism 182 and the threaded rod 183 enter between the two installation plates 164, when the horizontal plate 18 and the compression plate 181 are moved into position, the locking block 184 is rotated to gradually reduce the distance between the horizontal plate 18 and the compression plate 181, so that the horizontal plate 18 and the compression plate 181 are respectively abutted on the two vertical sides of the installation plate 164, at this time, the slot opening of the slot 185 is distributed upwards;

[0064] The second step is to lay the pull steel 161 between the two opposite steel plates 16, at this time, the pull steel 161 between the two steel plates 16 is called longitudinal steel, the two ends of the longitudinal steel are respectively placed in the gap between the two installation plates 164, at this time, the end of the pull steel 161 also enters the slot 185, and the pull steel 161 is arranged on the upper end surface of the horizontal plate 18.

[0065] The third step is to tighten the block 186 on the side of the compression plate 181 away from the horizontal plate 18 after the longitudinal steel is laid, the user rotates the tightening block 186 to move the tightening block 186 close to the compression plate 181, at this time, the tightening block 186 is pressed on the compression plate 181, and as the tightening block 186 rotates, the pull steel 161 is tensioned, so that the longitudinal steel is straightened, at this time, one person can tighten, the tightening block 186 on one steel plate 16 can be rotated first, so that one end of the pull steel 161 is rotated out, and then the tightening block 186 on the steel plate 16 opposite to the steel plate 16 is rotated, until the pull steel 161 is straightened; In addition, two people can rotate the tightening blocks 186 at both ends of the pull steel 161 at the same time; the construction and installation method is mostly used, and the use range is increased.

[0066] The fourth step is to lay the upper horizontal steel on the other two opposite steel plates 16 after the lower longitudinal steel is straightened, so that the horizontal steel is arranged on the longitudinal steel, and the two ends of the horizontal steel enter between the two installation plates 164 and are arranged on the horizontal plate 18, at this time, the height of the horizontal plate 18 is greater than that of the horizontal plate 18 for installing the longitudinal steel, and then the tightening block 186 is rotated to straighten the horizontal steel. At this time, the horizontal steel is close to the longitudinal steel.

[0067] Thus, the installation of the pull steel 161 is completed.

[0068] As Figure 8 And Figure 9 And Figure 10 AndFigure 11 The horizontal plate 18 and the pressing plate 181 are connected through the threaded rod 183 and the prism 182, so that the horizontal plate 18 and the pressing plate 181 abut on the mounting plate 164, thereby facilitating the change of the height position of the horizontal plate 18 and the pressing plate 181, and meeting the adjustment of the installation position of the longitudinal steel bars and the transverse steel bars.

[0069] In addition, a lower layer of the pull steel bars can be arranged on the inner lower side of the relative formwork according to the selection. The two ends of the pull steel bars extend out of the formwork and are locked through the nuts.

[0070] As shown in Figure 12 The vertical plate provided with the abutting rod 163 is provided with a mounting plate 164. At this time, the mounting plate 164 has high versatility, and the height of the foam plate 17 is greater than the height of the bearing platform 11. The side of the foam plate 17 facing the steel sheet pile 1 is provided with a plurality of vertical plates 19 which are inserted into each other. The vertical plates 19 can be wooden plates. The plate surfaces of the vertical plates 19 are flush. The adjacent vertical plates 19 are installed through the cooperation of the insertion blocks and the insertion grooves. The purpose of this design is to increase the flatness of the contact between the foam plate 17 and the steel sheet pile 1, thereby facilitating the pouring and forming of the bearing platform 11. The side edges of the two vertical plates 19 which are farthest apart are provided with extension plates 191 which extend in the direction of the formwork. One end of the steel plate 16 of the adjacent formwork extends into the extension plate 191, and the plate surface of the steel plate 16 abuts on one side of the foam plate 17. At this time, the design of the extension plate 191 facilitates the entry of the steel plate 16 and the abutment of the foam plate 17, so that the steel plate 16 on the formwork provides a limiting force to the two vertical plates 19 which are farthest apart. After the formwork is pulled out upward after the pouring and forming of the bearing platform 11, there is a gap between the extension plate 191 and the foam plate 17. The height of each vertical plate 19 is greater than the height of the foam plate 17, thereby facilitating the upward lifting of each vertical plate 19, so that there is a gap between the foam plate 17 and the steel sheet pile 1, and it is more convenient to pull out the steel sheet pile 1 later.

[0071] As shown in Figure 3 and Figure 4 and Figure 5 and Figure 6 The steel enclosing purlin 12 and the steel supporting plate 14 should be symmetrically and intervally removed, so as to reduce the local deformation and cracking caused by the excessive release of the instantaneous pre-stress.

[0072] The steel enclosing purlin 12 in the same combined foundation pit 13 is welded with a thick steel gusset plate 121 in the form of a triangle when the relative distance between the steel enclosing purlins 12 is close.

[0073] Obviously, those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application belong to the scope of the claims of the present application and the equivalent technologies thereof, the present application also intends to include these modifications and variations.

Claims

1. A construction method of a combined steel sheet pile cofferdam for a deep foundation pit of a river-crossing section platform, characterized in that, The process comprises the following steps: Steel sheet pile positioning, steel sheet pile setting, initial excavation, steel surrounding purlin installation, steel support plate installation, secondary excavation, cushion construction, pile cap construction, backfilling after completion, removal of steel support plate and steel surrounding purlin, and pulling out of steel sheet pile; A steel support plate is installed between adjacent and perpendicular steel surrounding purlins, and the two ends of the steel support plate are welded to the steel surrounding purlins; Steel sheet pile positioning and setting: after the pile cap is marked and no error is found after rechecking, the steel sheet pile insertion position is placed 1-1.1 meters away from the outside of the pile cap foundation edge line, the steel sheet pile is directly inserted, and the steel sheet pile edge line is laid out before insertion. The steel sheet pile is inserted vertically; The pile cap is marked and classified: one pile cap combination, two pile cap combinations, three pile cap combinations, and N pile cap combinations. The outer frame of the combination: the part without interference is set at 1-1.1 meters away from the outside of the pile cap foundation edge line, and the part with interference is excavated together and connected in the same combination foundation pit. The pile cap construction comprises reinforcing bar binding on the concrete cushion, pre-connecting the pile body reinforcing bar and the pile cap reinforcing bar, and then supporting the formwork connected to each other around the pile cap reinforcing bar and pouring the pile cap. The formwork comprises a steel plate on the side facing the pile cap reinforcing bar and a plurality of vertically distributed vertical plates on the side of the steel plate away from the pile cap reinforcing bar. The upper end of the vertical plate extends beyond the upper end of the steel plate. The vertical plates on the opposite steel plates are connected by tensioning the tie bar. When the position of the steel sheet pile on one side of the pile cap is less than 1 meter away from the outside of the pile cap foundation edge line and less than the thickness of the steel plate plus the vertical plate, the formwork at this position is replaced by the following structure: a plurality of closely fitted foam plates between the steel sheet pile and the pile cap reinforcing bar. Each foam plate is vertically distributed and arranged along the length direction of the pile cap. One side of each foam plate is in contact with the steel sheet pile. The end face of the outermost foam plate is in contact with the steel plate on the adjacent formwork. The vertical plates on the formwork corresponding to the foam plates are provided with contact rods horizontally contacting the side surface of the steel sheet pile. Each vertical plate comprises two U-shaped mounting plates connected to the plate surface of the steel plate. The U-shaped openings of the two mounting plates are distributed away from each other. One of the two vertical sides of the mounting plate is detachably connected to the steel plate by a screw. There is a gap between the two mounting plates of each vertical plate, and the tie bar passes through the gap. Each of the two mounting plates is provided with an adjusting member for adjusting the position of the tie bar.

2. The construction method of a combined steel sheet pile cofferdam for a river section pile cap deep foundation pit according to claim 1, characterized in that, The excavation of the earthwork is vertically divided into two layers from top to bottom, i.e. initial excavation: the first layer of soil is excavated to a position 0.5 meters below the steel support plate. An ordinary excavator is used for excavation, and the earthwork is directly transported outside by a transport vehicle. After the first layer of soil is excavated, the steel surrounding purlin and the steel support plate are constructed. After the steel support plate construction is completed, a long-arm excavator is used for the second layer of soil excavation, i.e. secondary excavation. After excavation to the pit bottom elevation, the concrete cushion is immediately poured. After the concrete strength of the concrete cushion reaches the required value, the subsequent pile head removal and pile cap construction can be carried out.

3. The construction method of a combined steel sheet pile cofferdam for a river section block deck deep foundation pit according to claim 2, characterized in that, Steel surrounding purlin, steel support plate installation: measure and mark the bottom elevation position of the steel surrounding purlin on the exposed steel sheet pile in the initial excavation, and weld the bracket; the steel surrounding purlin is hoisted to the bracket and welded, at this time the steel surrounding purlin is distributed around the inner wall of the steel sheet pile and closed to form a ring.

4. The construction method of a combined steel sheet pile cofferdam for a deep foundation pit of a river-crossing section pile cap according to claim 1, characterized in that, Two adjacent steel plates are connected by an angle steel, which is distributed along the height direction of the steel plate and connected with the side surface of each steel plate by bolts.

5. The construction method of a combined steel sheet pile cofferdam for a deep foundation pit of a river-crossing section pile cap according to claim 1, wherein The adjusting piece comprises a horizontal plate placed on the vertical side walls of each two mounting plates, which is above the steel plate and used for supporting the tendon, a pressing plate is placed on the vertical side walls of each two mounting plates, the pressing plate and the horizontal plate are respectively located on the two sides of the opposite two vertical side walls of the mounting plate, and a prism is arranged on the side of the horizontal plate facing the pressing plate, a threaded rod is coaxially arranged on the prism, a through hole is formed in the pressing plate for the threaded rod to pass through, and a locking block in contact with the pressing plate is threadedly connected to the threaded rod after the threaded rod passes through the pressing plate, an insertion slot is formed in the upper end surface of the pressing plate for the tendon to be inserted, when the tendon is not straightened and inserted into the insertion slot, the tendon is in contact with the upper end surface of the horizontal plate, and the two ends of the tendon are provided with threads and are connected with a screw block located on the side of the pressing plate away from the horizontal plate.

6. The construction method of a combined steel sheet pile cofferdam for a river section block deep foundation pit according to claim 5, characterized in that, The height of the foam plate is greater than the height of the pile cap, and the side of the foam plate facing the steel sheet pile is provided with a plurality of vertically inserted plates, the side edges of the two farthest vertical plates are provided with extension plates extending towards the formwork, and one end of the steel plate of the adjacent formwork extends into the extension plate, and the plate surface of the steel plate is in contact with one side of the foam plate.

7. The construction method of a combined steel sheet pile cofferdam for a deep foundation pit of a river-crossing section pile cap as claimed in claim 3, wherein Steel surrounding purlin, steel support plate removal: symmetrically and interval removal of steel surrounding purlin and steel support plate, to reduce the local deformation and cracking caused by excessive release of instantaneous pre-stress; When the steel surrounding purlins are close to each other in the same combined foundation pit, triangular thick steel shims are welded between the steel surrounding purlins.

Images