Construction method of high-pressure rotary jet grouting and sealing bottom steel sheet pile cofferdam

Abstract

The application relates to the technical field of a cofferdam construction of a bearing platform, and proposes a high-pressure rotary jet grouting bottom-sealing steel sheet pile cofferdam construction method, which comprises the following steps: S1, constructing a water ring-shaped construction platform; S2, cofferdam construction: inserting and driving a steel sheet pile at the inner periphery of the water ring-shaped construction platform to form a cofferdam; S3, driving a cast-in-situ pile in the cofferdam; S4, driving a temporary support on the outer side of the cofferdam, and enabling the temporary support to be in abutting contact with the outer periphery of the cofferdam; S5, bottom sealing of the cofferdam: high-pressure rotary jet grouting is carried out on the soil at the bottom of the cofferdam to form a bottom reinforcing layer; S6, pumping water in the cofferdam and constructing an inner support; S7, excavating the bottom reinforcing layer of the cofferdam to the design elevation of the bearing platform bottom; S8, binding a bearing platform steel mesh and supporting a bearing platform formwork; and S9, pouring bearing platform concrete; the application has the effect that the steel sheet pile of the cofferdam is not prone to displacement and deformation due to high-pressure rotary jet grouting.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of a cofferdam construction of a bearing platform, in particular to a high-pressure rotary jet grouting bottom-sealing steel sheet pile cofferdam construction method. BACKGROUND

[0002] At present, when a bearing platform of a bridge pier is constructed on the sea, a cofferdam is usually first built, the cofferdam is completed, bored piles are then driven in the cofferdam, the bottom of the cofferdam is sealed by high-pressure rotary jet grouting, the seawater in the cofferdam is then pumped out, and finally the bearing platform is constructed by binding steel bars and pouring concrete on the bottom of the cofferdam.

[0003] According to the above related technology, the steel sheet piles of the cofferdam are usually recycled, and the locking of part of the steel sheet piles is prone to damage due to long-term recycling, so that the connection strength of the adjacent steel sheet piles is low, and when high-pressure rotary jet grouting is performed on the cofferdam soil, the steel sheet piles of the cofferdam are prone to be impacted, so that the steel sheet piles with damaged locking are further displaced and deformed, and the cofferdam is prone to seepage. SUMMARY

[0004] In order to prevent the steel sheet piles of the cofferdam from being displaced and deformed due to high-pressure rotary jet grouting during the construction of the bearing platform, the application provides a high-pressure rotary jet grouting bottom-sealing steel sheet pile cofferdam construction method.

[0005] The high-pressure rotary jet grouting bottom-sealing steel sheet pile cofferdam construction method provided by the application adopts the following technical scheme:

[0006] A high-pressure rotary jet grouting bottom-sealing steel sheet pile cofferdam construction method comprises the following steps:

[0007] S1: constructing a water ring-shaped construction platform;

[0008] S2: cofferdam construction: driving steel sheet piles in the water ring-shaped construction platform to form a cofferdam;

[0009] S3: driving bored piles in the cofferdam;

[0010] S4: driving a temporary support on the outside of the cofferdam and abutting the temporary support against the outer periphery of the cofferdam;

[0011] S5: cofferdam bottom sealing: high-pressure rotary jet grouting is performed on the soil at the bottom of the cofferdam to form a bottom reinforcement layer;

[0012] S6: pumping water in the cofferdam and constructing an internal support

[0013] S7: excavating the bottom reinforcement layer of the cofferdam to the design elevation of the bearing platform;

[0014] S8: binding a bearing platform steel bar mesh and supporting a bearing platform formwork;

[0015] S9: pouring concrete for the bearing platform;

[0016] The temporary support comprises two groups of vertically arranged columns, and a plurality of cross struts are connected between the two groups of columns.

[0017] By adopting the above technical scheme, after the cofferdam is constructed, the temporary support is inserted and driven outside the periphery of the cofferdam and abuts against the periphery of the cofferdam, the columns and the cross struts on the temporary support are used to limit the steel sheet piles on the cofferdam, so as to reduce the displacement of the steel sheet piles on the cofferdam due to the high-pressure rotary jet grouting of the soil at the bottom of the cofferdam, the damage and deformation of the locking joints of the adjacent steel sheet piles, and the seepage of the cofferdam.

[0018] Preferably, the two groups of columns of the temporary support are respectively provided with a splicing piece and a splicing part on the side away from each other, and the adjacent temporary supports on the same side of the cofferdam are spliced with each other through the splicing piece and the splicing part.

[0019] By adopting the above technical scheme, the connection integrity of the adjacent temporary supports is improved through the splicing piece, so as to better support the cofferdam through the temporary support, and reduce the displacement and deformation of the steel sheet piles on the cofferdam due to the impact during the subsequent high-pressure rotary jet grouting operation of the soil at the bottom of the cofferdam.

[0020] Preferably, in step S6, during the water pumping into the cofferdam, when it is found that the adjacent steel sheet piles of the cofferdam seep, a plugging piece is installed between the outside of the steel sheet pile with the leakage of the locking joint and the temporary support to plug the leakage of the locking joint of the steel sheet pile.

[0021] The plugging piece comprises a support rod, and a gas bag piece is arranged around the outer periphery of the support rod, when the gas bag piece is inflated, the gas bag piece expands and covers the locking joint of the adjacent steel sheet piles, and the outer periphery of the gas bag piece abuts against the outside of the cofferdam and the temporary support.

[0022] By adopting the above technical scheme, the expansion of the gas bag piece covers the splicing joint of the adjacent steel sheet piles, realizes the sealing and water stopping of the splicing joint of the adjacent steel sheet piles, reduces the seepage of seawater and the like into the cofferdam through the splicing joint of the steel sheet piles, and through the abutment of the outer periphery of the gas bag piece after inflation and expansion against the temporary support and the cofferdam, the temporary support and the cofferdam can be used to limit the gas bag piece, so that the gas bag piece can better abut against the outside of the cofferdam steel sheet piles to better plug the locking joint of the steel sheet piles.

[0023] Preferably, the annular construction platform is further provided with a temporary construction support, the temporary construction support comprises two groups of parallelly arranged guide rail plates, the two groups of guide rail plates are respectively used for supporting the two sides caterpillar belts of the jet grouting drilling machine base; the two groups of guide rail plates are left with a spacing; the annular construction platform is provided with two groups of slide rails corresponding to the two groups of guide rail plates, the slide rails are arranged perpendicularly to the length direction of the guide rail plates, and the two ends of the guide rail plates are respectively slidably connected to the two groups of slide rails through slide blocks; the annular construction platform is further provided with a driving assembly, and the driving assembly is used for driving the two groups of guide rail plates to reciprocatingly slide along the slide rails.

[0024] By adopting the above technical scheme, when the bored pile is driven or the high-pressure jet grouting is performed on the soil body at the bottom of the cofferdam, the jet grouting drilling machine is moved to the temporary construction platform and the caterpillar belts on the two sides of the jet grouting drilling machine are respectively arranged on the two groups of guide rail plates, the gap between the drill rod on the jet grouting drilling machine and the two groups of guide rail plates is arranged oppositely, and the two groups of guide rail plates are driven to slide along the slide rails by the driving assembly, and the jet grouting drilling machine is moved along the extension direction of the two groups of guide rail plates at the same time, so that the jet grouting drilling machine is quickly and conveniently moved to different construction stations.

[0025] Preferably, the bottom of the two groups of guide rail plates is provided with a plurality of connecting rods, the plurality of connecting rods are uniformly distributed along the length direction of the guide rail plates, the two ends of the connecting rods are respectively connected to the two groups of guide rail plates, the driving assembly comprises a plurality of driving members, the plurality of driving members correspond to the plurality of connecting rods one by one, the driving member comprises two groups of oppositely arranged winches, the two pairs of winches of the same group of driving members are oppositely arranged at the two ends of the corresponding connecting rod, and the cable of the winch is detachably connected to the end of the corresponding connecting rod through a connecting piece.

[0026] By adopting the above technical scheme, the two groups of guide rail plates can drive the jet grouting drilling machine to slide along the length direction of the guide rail by winding and unwinding the two groups of winch cables, so that the jet grouting drilling machine is conveniently moved to different construction stations by cooperating with the movement of the jet grouting drilling machine on the guide rail plate. The construction of the bored pile and the subsequent rotary grouting is more simple and convenient. The cable of the winch is detachably connected to the end of the connecting rod through the connecting piece. On the one hand, the winches at the two ends of the connecting rod can improve the bending resistance and overall strength of the two groups of guide rail plates during the movement of the connecting rod by winding and unwinding the cable, thereby reducing the bending deformation of the guide rail plate at the suspended position. On the other hand, the end of the cable is detachably connected to the end of the connecting rod through the connecting piece. When the cable interferes with the subsequent cofferdam steel sheet pile insertion or temporary support installation, the connection between the cable and the end of the connecting rod can be temporarily disconnected.

[0027] Preferably, the two ends of the connecting rod are provided with lifting rings; the connecting piece comprises a shackle arranged at the end of the winch cable, and the cable is connected to the lifting ring at the end of the corresponding connecting rod through the shackle.

[0028] By adopting the technical scheme, detachable connection between the connecting rods and the connecting rods is realized, when the hoist and the cofferdam or the temporary support to be constructed interfere with each other, the connection between the shackle and the lifting ring can be temporarily disconnected, and the erection of the cofferdam steel sheet pile or the erection of the temporary support is facilitated.

[0029] Preferably, the guide rail plates are vertically upwardly provided with limit plates on opposite sides.

[0030] By adopting the technical scheme, the slot-shaped structure formed by the guide rail plates and the limit plates on the two sides limits and guides the caterpillar track of the rotary jet drilling machine, so that the rotary jet drilling machine is not easy to slide out of the guide rail plate during the travel on the guide rail plate.

[0031] Preferably, the support rod extends from the bottom end of the air bag member and the bottom end of the support rod is sharp.

[0032] By adopting the technical scheme, when the plugging member is constructed, the support rod can be driven into the soil layer under the water, so that the construction of the plugging member is more simple and convenient.

[0033] In summary, the present application has at least one of the following beneficial technical effects:

[0034] 1. After the cofferdam is constructed, the temporary support is inserted and driven into the soil layer outside the cofferdam, and the steel sheet pile of the cofferdam is supported and limited by the temporary support, so that the displacement of the steel sheet pile of the cofferdam occurs when the high-pressure rotary jet is performed to the bottom of the cofferdam, and the leakage occurs at the locking port of the adjacent steel sheet pile.

[0035] 2. The temporary construction support is further provided on the annular construction platform, the temporary construction support includes two groups of parallel guide rail plates, the annular construction platform is provided with two groups of sliding rails for the two groups of guide rail plates, the guide rail plates are slidably connected to the two groups of sliding rails through sliding blocks at both ends, and the annular construction platform is further provided with a driving assembly for driving the two groups of guide rail plates to slide along the sliding rails. When the high-pressure bored pile or the high-pressure rotary jet grouting is constructed, the rotary jet drilling machine can be moved, and the caterpillar track wheels on both sides of the rotary jet drilling machine are located on the two groups of guide rail plates, and the two groups of guide rail plates are driven to slide by the driving assembly, and the rotary jet drilling machine itself travels along the guide rail plates, so that the rotary jet drilling machine is quickly and conveniently moved to different construction stations.

[0036] 3. The two groups of stand columns of the temporary support are provided with a splicing part and a splicing member on the side away from each other, and the adjacent temporary supports are spliced by the splicing part and the splicing member, so as to improve the connection integrity of the adjacent temporary supports, and better limit the displacement and deformation of the steel sheet pile on the cofferdam. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a state diagram of the present application for illustrating the construction of the annular construction platform and the high-pressure bored pile.

[0038] Figure 2 is a state schematic diagram for illustrating the construction of a cofferdam according to an embodiment of the present application.

[0039] Figure 3 is a state schematic diagram for illustrating high-pressure rotary jet grouting of the bottom of a cofferdam according to an embodiment of the present application.

[0040] Figure 4 is a state schematic diagram for illustrating the construction of an internal support in a cofferdam according to an embodiment of the present application.

[0041] Figure 5 is a state schematic diagram for illustrating the construction of a pile cap according to an embodiment of the present application.

[0042] Figure 6 is a schematic diagram for illustrating a ring-shaped construction platform and a temporary construction support according to an embodiment of the present application.

[0043] Figure 7 is a structural schematic diagram for illustrating a temporary support according to an embodiment of the present application.

[0044] Figure 8 is Figure 6 is an enlarged schematic diagram of part A.

[0045] Figure 9 is Figure 6 is an enlarged schematic diagram of part B.

[0046] Figure 10 is a structural schematic diagram for illustrating a plugging member according to an embodiment of the present application.

[0047] Legend of reference signs:

[0048] 1, ring-shaped construction platform; 2, rotary jet drill; 20, cast-in-place pile; 21, crawler crane; 22, vibration hammer; 3, cofferdam; 30, bottom reinforcing layer; 31, steel sheet pile; 32, internal support; 33, pile cap; 34, temporary support; 341, upright column; 342, cross brace; 351, spliced pipe; 36, main splicing plate; 37, auxiliary splicing plate; 4, guide rail plate; 40, limiting plate; 41, sliding rail; 42, sliding seat; 43, connecting rod; 431, lifting ring; 44, winch; 45, cable; 451, shackle; 5, support rod; 51, air bag member. DETAILED DESCRIPTION

[0049] The following will be described in detail with reference to the accompanying drawings. Figures 1-10 The present application will be further described in detail.

[0050] An embodiment of the present application discloses a high-pressure rotary jet grouting bottom sealing steel sheet pile cofferdam construction method, referring to Figures 1 to 5 , comprising the following steps:

[0051] S1: Constructing a water ring construction platform 1.

[0052] S2: Cofferdam 3 construction: Inserting steel sheet piles 31 at the inner circumferential opening of the water ring construction platform 1 to form a cofferdam 3; in this embodiment, the steel sheet piles 31 are existing Larsen steel sheet piles. The steel sheet piles 31 are inserted by the crawler crane 21 in cooperation with the vibration hammer 22.

[0053] S3: Drilling and pouring piles 20 in the cofferdam 3 by the rotary jet drilling machine 2.

[0054] S4: Inserting temporary support members 34 outside the cofferdam 3 and arranging the temporary support members 34 in abutment with the outer periphery of the cofferdam 3. The temporary support members 34 are inserted by the crawler crane 21 in cooperation with the vibration hammer 22.

[0055] S5: Cofferdam 3 bottom sealing: High-pressure rotary jet grouting is performed on the soil at the bottom of the cofferdam 3 to form a bottom reinforcement layer 30; the specific steps are as follows:

[0056] S5.1: Positioning the rotary jet drilling machine 2;

[0057] S5.2: Drilling a pilot hole to a depth of 5m below the bottom of the pile cap 33, pulling out the core tube, and replacing it with a jet grouting tube inserted into the soil 5m below the bottom of the pile cap 33;

[0058] S5.3: High-pressure rotary jet grouting construction: The grouting height is 5m of soil below the pile cap 33. The grouting water-cement ratio is 1:1, and the grouting spacing is arranged in a Wulff pattern according to the grouting holes, with a hole spacing of not less than 100cm.

[0059] S6: Water pumping in the cofferdam 3 and construction of internal supports 32; the specific steps are as follows:

[0060] S6.1: Pumping water to 50cm below the first internal support 32 and installing the first internal support 32;

[0061] S6.2: Continuing to pump water and dredge to 50cm below the second internal support 32 and installing the second internal support 32;

[0062] In step S6, when the water in the cofferdam 3 is pumped out, if leakage occurs at the locking port of the steel sheet pile 31 of the cofferdam 3, a plugging member is installed between the outer side of the steel sheet pile 31 with leakage at the locking port and the temporary support member 34 to plug the leakage of the adjacent steel sheet pile 31.

[0063] S7: Excavating the bottom reinforcement layer 30 of the cofferdam 3 to the design elevation of the bearing platform bottom and leveling the surface of the bottom reinforcement layer 30.

[0064] S8: Binding the reinforcement mesh of the pile cap 33 and supporting the pile cap 33 formwork; before binding the reinforcement mesh, the interior of the cofferdam 3 and the pile heads of the piles 20 should be cleaned.

[0065] S9: pouring concrete for the bearing platform 33.

[0066] Referring to Figure 6 and Figure 7 , the temporary support 34 comprises two groups of vertically arranged columns 341, and a plurality of cross struts 342 are connected between the two groups of columns 341. In the embodiment, the columns 341 and the cross struts 342 are both metal square tubes. In other embodiments, the columns 341 and the cross struts 342 can also be I-beams.

[0067] Referring to Figure 7 and Figure 8 , the two groups of columns 341 are respectively provided with a splicing part and a splicing piece on one side away from each other. The splicing part and the splicing piece of the adjacent temporary supports 34 on the same side of the cofferdam 3 are spliced and arranged. The splicing piece comprises a fixed outer main splicing plate 36 of the column 341. The side of the main splicing plate 36 away from the column 341 is also vertically connected with a secondary splicing plate 37. The main splicing plate 36 and the secondary splicing plate 37 are arranged in a T shape. The splicing part comprises a splicing pipe 351 vertically connected to the outside of the column 341. The side of the splicing pipe 351 away from the column 341 is provided with a splicing groove. The splicing groove is open at both ends and is used for inserting the main splicing plate 36. When splicing the adjacent temporary supports 34, the splicing piece is inserted into the splicing pipe 351 through the splicing groove, so that the splicing of the adjacent temporary supports 34 can be realized. The connection integrity of the adjacent temporary supports 34 can be improved through the splicing part and the splicing piece.

[0068] Referring to Figure 6 and Figure 8 , in step S4, when the temporary support 34 is constructed, the bottom ends of the two groups of columns 341 of the temporary support 34 are driven into the soil layer at the bottom of the water by the vibration hammer 22, and the cross struts 342 of the temporary support 34 abut against the outside of the steel sheet pile 31 of the cofferdam 3, so as to limit and support the steel sheet pile 31. This can reduce the impact of high-pressure rotary jet grouting on the steel sheet pile 31 of the cofferdam 3, so as to prevent the steel sheet pile 31 from being displaced and deformed, and further prevent the cofferdam 3 from being damaged and leaking.

[0069] Referring to Figure 6 and Figure 9The annular construction platform 1 is further provided with a temporary construction support, the temporary construction support comprises two groups of guide rail plates 4 arranged in parallel, the two groups of guide rail plates 4 span the opening of the annular construction platform 1, and the two groups of guide rail plates 4 are respectively used for supporting the caterpillar tracks on both sides of the base of the rotary jet drilling machine 2; a space is left between the two groups of guide rail plates 4 for the drill of the rotary jet drilling machine 2 to pass through. The annular construction platform 1 is fixed with two groups of sliding rails 41 arranged in parallel, the length direction of the sliding rails 41 is perpendicular to the length direction of the guide rail plates 4, in this embodiment, the sliding rails 41 are I-beams; the two ends of the two groups of guide rail plates 4 are respectively slidably connected to the two groups of sliding rails 41 through sliding seats 42; and the annular construction platform 1 is further provided with a driving assembly for driving the two groups of guide rail plates 4 to slide reciprocatingly along the sliding rails 41. Through the above arrangement, when the cast-in-place pile 20 is constructed or the high-pressure rotary jet grouting is performed on the soil at the bottom of the cofferdam 3, the caterpillar tracks on both sides of the base of the rotary jet drilling machine 2 are respectively placed on the two groups of guide rail plates 4, the two groups of guide rail plates 4 are driven to slide along the sliding rails 41 by the driving assembly, and at the same time, the rotary jet drilling machine 2 itself advances on the two groups of guide rail plates 4 through the caterpillar track base, so that the rotary jet drilling machine 2 can be quickly and conveniently moved to different construction stations.

[0070] With reference to Figure 6 and Figure 9 The guide rail plates 4 are respectively connected to limiting plates 40 vertically upward on opposite sides, and the two groups of limiting plates 40 and the guide rail plates 4 form a groove-shaped structure for guiding and limiting the caterpillar tracks of the rotary jet drilling machine 2. The bottom of the two groups of guide rail plates 4 is provided with a plurality of connecting rods 43, the plurality of connecting rods 43 are evenly distributed along the length direction of the guide rail plates 4, the two ends of the connecting rods 43 are respectively welded and fixed at the bottom of the two groups of guide rail plates 4, and the two ends of the connecting rods 43 respectively extend out of one side of the two groups of guide rail plates 4 away from each other. The driving assembly comprises a plurality of driving members corresponding to the plurality of connecting rods 43, and the driving member comprises two groups of winches 44 fixed on the annular construction platform, the two groups of winches 44 are respectively arranged opposite to the two ends of the connecting rods 43, and the ends of the cables 45 on the winches 44 are detachably connected to the ends of the connecting rods 43 through connecting members. Through the above arrangement, the two ends of the connecting rods 43 are detachably connected to the cables 45 of the two groups of winches 44 respectively; on the one hand, the two groups of guide rail plates 4 can be simultaneously driven to slide along the sliding rails 41 by winding and unwinding the cables 45 through the two groups of winches 44; at the same time, the bending resistance and the connection integrity of the two groups of guide rail plates 4 can be improved by the cables 45 cooperating with the connecting rods 43, so that the guide rail plates 4 are not easy to deform during the advancing of the rotary jet drilling machine 2 on the two groups of guide rail plates 4; when the steel sheet piles 31 are subsequently constructed, the connection between the cables 45 and the connecting rods 43 above the opening of the annular construction platform 1 can be disconnected, so as to reduce the interference of the cables 45 of the winches 44 with the steel sheet piles 31 or the temporary support 34 insertion station.

[0071] With reference to Figure 6 and Figure 9The connecting rod 43 has a hanger ring 431 welded and fixed at both ends, the connecting member includes a shackle 451 arranged at the end of the cable 45, and the shackle 451 is an existing arc-shaped shackle; the shackle 451 is buckled on the hanger ring 431 at the corresponding end of the connecting rod 43, so as to realize detachable connection between the connecting rod 43 and the cable 45 of the hoist 44.

[0072] With reference to Figure 6 and Figure 9 In step S6, before the inner support 32 is installed, the temporary construction support is removed.

[0073] With reference to Figure 8 and Figure 10 The blocking member includes a support rod 5 and an air bag member 51 arranged around the outer shaft of the support rod 5, the bottom end of the support rod 5 extends to the bottom end of the air bag member 51 and the bottom end of the support rod 5 is sharp, so as to facilitate the bottom end of the support rod 5 to be punched into the underwater soil to limit the blocking member; when the air bag member 51 is inflated, the air bag member 51 blocks the locking part of the steel sheet pile 31 and the outer periphery of the air bag member 51 abuts against the outer side of the temporary support member 34 and the steel sheet pile 31, so as to facilitate the temporary support member 34 to limit the air bag member 51 to move away from the steel sheet pile 31, thereby facilitating the air bag member 51 to better block the water seepage locking part of the steel sheet pile 31.

[0074] The above are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, therefore: any equivalent changes made on the structure, shape and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A method for constructing a high-pressure jet grouting bottom-sealing steel sheet pile cofferdam, characterized in that: It comprises the following steps: S1: constructing a water ring construction platform (1); S2: cofferdam (3) construction: inserting and driving steel sheet piles (31) in the inner periphery of the water ring construction platform (1) to form a cofferdam (3); S3: driving bored piles (20) in the cofferdam (3); S4: driving temporary support members (34) on the outside of the cofferdam (3) and arranging the temporary support members (34) in abutting contact with the outer periphery of the cofferdam (3); S5: cofferdam (3) bottom sealing: high-pressure rotary jet grouting is performed on the bottom soil of the cofferdam (3) to form a bottom reinforcement layer (30); S6: pumping water out of the cofferdam (3) and constructing an internal support (32) S7: excavating the bottom reinforcement layer (30) of the cofferdam (3) to the design elevation of the bearing platform bottom; S8: binding the reinforcement mesh of the bearing platform (33) and supporting the bearing platform (33) formwork; S9: pouring concrete for the bearing platform (33); The temporary support member (34) comprises two groups of vertically arranged columns (341), and a plurality of cross bracing bars (342) are connected between the two groups of columns (341); in step S6, during the water pumping process in the cofferdam (3), when it is found that the adjacent steel sheet piles (31) of the cofferdam (3) are leaking at the joint, a plugging member is installed between the leaking steel sheet pile (31) on the outside and the temporary support member (34) to plug the leakage at the joint of the steel sheet pile (31); The plugging member comprises a support rod (5), and a gas bag member (51) is arranged around the outer periphery of the support rod (5); when the gas bag member (51) is inflated, the gas bag member (51) expands and covers the joint of the adjacent steel sheet pile (31), and the outer periphery of the gas bag member (51) is in abutting contact with the outside of the cofferdam (3) and the temporary support member (34); The support rod (5) extends out of the bottom end of the gas bag member (51), and the bottom end of the support rod (5) is pointed.

2. The construction method of a high-pressure rotary jet grouting sealing bottom steel sheet pile cofferdam according to claim 1, characterized in that: The two groups of columns (341) of the temporary support member (34) are respectively provided with a joint member and a joint portion on the side away from each other, and the adjacent temporary support members (34) on the same side of the cofferdam (3) are arranged in abutting contact with each other through the joint member and the joint portion.

3. The construction method of a high-pressure rotary jet grouting sealing bottom steel sheet pile cofferdam according to claim 1, characterized in that: The ring construction platform (1) is also provided with a temporary construction support, which comprises two groups of parallel arranged guide rail plates (4), and the two groups of guide rail plates (4) are respectively used for supporting the two sides of the rotary jet grouting drilling machine (2) base; the two groups of guide rail plates (4) are spaced apart; the ring construction platform (1) is provided with two groups of slide rails (41) corresponding to the two groups of guide rail plates (4), the length direction of the slide rails (41) is perpendicular to the length direction of the guide rail plates (4), and the two ends of the guide rail plates (4) are respectively slidably connected to the two groups of slide rails (41) through slide blocks; the ring construction platform (1) is also provided with a driving assembly, and the driving assembly is used for driving the two groups of guide rail plates (4) to reciprocally slide along the slide rails (41).

4. The construction method of a high-pressure rotary jet grouting sealing bottom steel sheet pile cofferdam according to claim 3, characterized in that: The bottom of the guide rail plate (4) is provided with a plurality of connecting rods (43), the plurality of connecting rods (43) are uniformly distributed along the length direction of the guide rail plate (4), the two ends of the connecting rod (43) are connected to the two groups of guide rail plates (4) respectively, the driving assembly comprises a plurality of driving members, the plurality of driving members correspond to the plurality of connecting rods (43) one by one, the driving member comprises two groups of oppositely arranged winches (44), the two pairs of winches (44) of the same group of driving members are oppositely arranged at the two ends of the corresponding connecting rod (43), and the cable (45) of the winch (44) is detachably connected with the end of the corresponding connecting rod (43) through a connecting piece.

5. The construction method of a high-pressure rotary jet grouting sealing bottom steel sheet pile cofferdam according to claim 4, characterized in that: The two ends of the connecting rod (43) are provided with lifting rings (431); the connecting piece comprises a shackle (451) arranged at the end of the cable (45) of the winch (44), and the cable (45) is connected with the lifting ring (431) at the end of the corresponding connecting rod (43) through the shackle (451).

6. The construction method of a high-pressure rotary jet grouting sealing bottom steel sheet pile cofferdam according to claim 3, characterized in that: The guide rail plate (4) is vertically provided with a limiting plate (40) on the opposite two sides.

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