Construction method for dismantling a hub cofferdam

Abstract

The application provides a construction method for dismantling a hub cofferdam, and belongs to the technical field of water conservancy hub construction. The application provides a construction method for dismantling a cofferdam unit, specifically including upper structure dismantling, excavation and dredging of wall soil, and dismantling of a diaphragm wall including an overwater part and an underwater part by using a rope saw process. The application also provides a construction method for dismantling a hub cofferdam, including dividing a cofferdam unit and dismantling the cofferdam unit. The construction method for dismantling the hub cofferdam effectively overcomes the difficulty of dismantling a high-strength, high-steel-content and high-underwater-volume cofferdam diaphragm wall, successfully completes the splitting, hoisting and dismantling of a diaphragm wall split block with a maximum single block of about 126 tons, protects newly built and already built buildings and structures, and realizes uninterrupted and unsealed navigation construction, and has a broad application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of water conservancy hub construction and relates to a construction method for hub cofferdam dismantling. BACKGROUND

[0002] In the construction process of large ship lock and other water conservancy hub repair, reconstruction and expansion, etc., the construction is often ensured to be carried out by building cofferdams. For rivers with deep water depth and complex hydrology, the height, water entry depth and steel content of the cofferdam are also large, and the hub cofferdam needs to be dismantled after the completion of the construction. There are the following difficulties in the construction of large water conservancy hub cofferdam dismantling: first, the cofferdam has large volume, deep water entry depth, large steel content and high strength, which causes great difficulty in cofferdam segmentation and hoisting; second, the surrounding environment of the water conservancy hub is complex, and the construction should not damage the surrounding facilities; third, the water conservancy hub often involves traffic choke points, and the construction caused by the closure of navigation will bring significant losses. Therefore, selecting a suitable construction method for dismantling the water conservancy hub cofferdam, especially selecting a suitable construction method for dismantling the high-strength, high-steel-content and high-underwater-volume cofferdam diaphragm wall, is a bottleneck problem that needs to be solved in the prior art.

[0003] Chinese Patent Application 202111187626.4 discloses a construction method for dismantling an end cofferdam, including the following steps: S1: backfilling sand into the foundation pit and dismantling the first support; S2: backfilling sand to the top elevation of the tunnel butt joint section and sloping to the second support; S3: constructing a water retaining wall, pouring water, and dismantling the second support of the stable layer; S4: dismantling the first second support and the crown beam; S5: cleaning the backfilling sand and concrete in the steel pipe pile and cutting the steel pipe pile; S6: dismantling the remaining second support of the stable layer and pouring water; S7: dismantling the mold bag cofferdam and removing the upper part of the cut steel pipe pile; S8: dismantling the remaining mold bag cofferdam and removing the backfilling sand in the foundation pit. However, this technology is for the steps of dismantling the end cofferdam constructed in the immersed tunnel project, does not involve how to dismantle the water conservancy hub cofferdam, and does not involve the method for dismantling the high-strength, high-steel-content and high-underwater-volume diaphragm wall in the water conservancy hub cofferdam in the complex hydrological environment, and thus the technology is difficult to be applied to the dismantling construction of the hub cofferdam.

[0004] Chinese patent application 202110152836.3 discloses a construction method for the demolition of a riverbank cofferdam structure, which changes the soil backfill in the prior art to water backfill, takes advantage of the surrounding environment, and when the water backfill reaches a certain height, the pressure values of the river water outside the cofferdam and the backfill water inside the cofferdam reach stability, and then the riverbank cofferdam structure is demolished for construction, which has the advantages of high efficiency and low cost. However, this technology does not involve the demolition method of high-strength, high-steel-content, and high-underwater-volume diaphragm walls in the water conservancy hub cofferdam in complex hydrological environments, and thus this technology is also difficult to apply to the demolition construction of the hub cofferdam.

[0005] Chinese patent application 202211508622.6 discloses a construction method for demolishing a reinforced concrete longitudinal cofferdam using a winning cut machine. This method solves the problem of reinforced concrete cofferdam falling into the river channel during blasting construction, which is difficult to clean up and affects the operation of the gate. However, this method only provides for the demolition of reinforced concrete longitudinal cofferdams in rivers with small flow, and each cofferdam weighs only about 3-4 tons. In complex hydrological environments and deep river channels, large diaphragm walls with high strength, high steel content, and high underwater volume need to be demolished, and this method cannot solve this problem.

[0006] In summary, the prior art cannot provide an efficient cofferdam hub demolition method, especially a demolition method involving the demolition of large-size diaphragm walls with large volume, high strength, high steel content, and high underwater volume. SUMMARY

[0007] Therefore, in view of the fact that the prior art cannot provide an efficient cofferdam hub demolition method, especially a demolition method involving the demolition of large-size diaphragm walls with large volume, high strength, high steel content, and high underwater volume, the purpose of the present application is to provide a construction method for the demolition of a hub cofferdam.

[0008] To achieve the above-mentioned purpose of the application, in one aspect, the present application provides a construction method for the demolition of a cofferdam unit, comprising the following steps:

[0009] S1, demolish the superstructure, excavate and dredge the soil between the walls;

[0010] S2, use a rope saw process to demolish the diaphragm wall;

[0011] In step S2, the diaphragm wall includes at least one of a double-row reinforced concrete diaphragm wall, a double-row lattice reinforced concrete diaphragm wall, and a three-row lattice reinforced concrete diaphragm wall.

[0012] As an example of the present application, the diaphragm wall is selected from a double-row reinforced concrete diaphragm wall, a double-row lattice reinforced concrete diaphragm wall, and a three-row lattice reinforced concrete diaphragm wall.

[0013] Preferably, the upper structure comprises a pavement, backfill, retaining wall, and tie beam.

[0014] Preferably, the upper structure demolition comprises the following steps: S101, breaking the pavement; S102, excavating the backfill; S103, breaking the retaining wall; and S104, breaking the tie beam.

[0015] Preferably, the step S2 comprises the following steps:

[0016] S210, dividing the diaphragm wall into cutting units; S220, drilling and hoisting holes; S230, drilling cutting holes; S240, cutting using a rope saw; S250, hoisting and cutting blocks, and crushing and transporting away.

[0017] More preferably, the step S210 specifically comprises: dividing the diaphragm wall into a plurality of cutting units, wherein the first cutting unit is divided in a trapezoidal structure with the upper part being wide and the lower part being narrow.

[0018] More preferably, the step S220 comprises the following steps:

[0019] S221, determining the hoisting hole position according to the size of the cutting unit in step S210, and lofting;

[0020] S222, connecting the hydraulic system placed on land with the drill pipe and track system supported on water by pipelines;

[0021] S223, fixing the drill pipe track on the surface of the diaphragm wall, and adjusting the verticality and horizontality of the track;

[0022] S224, operating using the drill pipe operation platform;

[0023] S225, taking out the core sample, and protecting and marking the hoisting hole.

[0024] More preferably, the step S230 comprises the following steps:

[0025] S231, dredging on both sides of the diaphragm wall; S232, underwater positioning; S233, drilling with underwater assistance; and S234, installing underwater directional wheels.

[0026] As an example of the present application, the step S232 specifically comprises: measuring the underwater drilling elevation by the positioning bracket and the plumb line cooperated on the shore, checking the depth by the scale display through underwater observation, and further adjusting the cutting drill pipe after determining the cutting hole position by further measurement.

[0027] More preferably, the step S240 comprises the following steps:

[0028] S241, the cutting platform ship is in place; S242, the cutting rope is cut underwater, and the rope head is taken back to the water surface; S243, the cutting rope is connected with the track cutting machine; S244, the vertical seam is cut; S245, the bottom transverse seam is cut.

[0029] Preferably, in the process of step S245, the wedge-shaped steel plate gasket is driven into the part of the bottom transverse seam that has been cut. Driving the wedge-shaped steel plate gasket into the part of the bottom transverse seam that has been cut can prevent the diaphragm wall concrete block from sinking and pressing the cutting rope during the cutting process; and the wedge-shaped steel plate gasket has high pressure resistance and is not easy to deform in this process.

[0030] More preferably, in step S250, the hoisting and cutting block is hoisted onto the shore using a derrick crane; and the derrick crane is connected to the cutting block through a lifting tool.

[0031] Preferably, the lifting tool structure is as shown in Figures 13-17 .

[0032] The specific structure is as follows:

[0033] A diaphragm wall block hoisting tool, comprising two structural members arranged opposite to each other, a first shaft and a second shaft are arranged between the two structural members, and the first shaft is arranged above the second shaft; the structural member comprises a first side plate and a second side plate, the upper end of the first side plate and the upper end of the second side plate are connected through a derrick; a front baffle assembly is arranged between the first side plate and the second side plate, a rear baffle assembly is arranged on the back of the front baffle assembly, and a reinforcing rib assembly is arranged below the rear baffle assembly.

[0034] Further, the first shaft sequentially passes through the rear baffle assembly, the front baffle assembly of one of the structural members, and the front baffle assembly, the rear baffle assembly of the other structural member.

[0035] Further, the second shaft sequentially passes through the front baffle assembly of one of the structural members and the front baffle assembly of the other structural member.

[0036] Further, the front baffle assembly comprises a first baffle and a second baffle arranged at intervals, the first baffle and the second baffle are arranged in parallel, and the first baffle and the second baffle are connected by a plurality of first partitions.

[0037] Further, the plurality of first partitions are all arranged horizontally and are arranged at intervals in the vertical direction.

[0038] Further, the first baffle and the second baffle are both provided with a waist hole for the first shaft to pass through and a through hole for the second shaft to pass through.

[0039] Further, the backplate assembly comprises a third backplate and a fourth backplate arranged in parallel, and a plurality of second partitions arranged horizontally between the third backplate and the fourth backplate, and a plurality of third partitions arranged vertically between the third backplate and the fourth backplate.

[0040] Further, the reinforcing rib assembly comprises a plurality of triangular partitions arranged in parallel in the horizontal direction, and a fourth partition arranged between the plurality of triangular partitions.

[0041] Further, the first shaft and the second shaft are made of a mixed material of 40 steel and 45Cr steel, the diameter of the first shaft is 100 mm, and the diameter of the second shaft is 115 mm.

[0042] Further preferably, the first shaft and the second shaft are prepared by a modulated heat treatment forming method.

[0043] In the examples of the present application, the first shaft and the second shaft prepared by the modulated heat treatment forming method have stronger mechanical properties, and the hoist using the first shaft and the second shaft successfully realizes the safe hoisting of a diaphragm wall cutting block of about 126 tons.

[0044] On the other hand, the present application provides a construction method for dismantling a hub cofferdam, comprising the following steps:

[0045] T1, dividing the upstream part and the downstream part of the cofferdam into cofferdam units, respectively;

[0046] T2, simultaneously removing the cofferdam units of the upstream part and the downstream part in step T1;

[0047] In step T2, the construction method for removing the cofferdam units is selected from the construction method for removing the cofferdam units described above.

[0048] In the examples of the present application, the cofferdam units of the upstream part in step T2 are removed in the downstream direction, and the cofferdam units of the downstream part are removed from the middle to the two sides.

[0049] Preferably, the cofferdam units are removed from the middle to the two sides simultaneously. Further, the cofferdam units are removed from multiple positions in the middle simultaneously and removed to the two sides, respectively. By using the above method to remove the cofferdam units of the downstream part, the construction period can be shortened, and the adverse effects of back siltation caused by the rise and fall of the downstream tide on the construction process can be effectively reduced.

[0050] Preferably, in step T2, the continuous beam top is used as a construction road for waste disposal.

[0051] Still in another aspect, the application provides the application of the construction method for removing the cofferdam unit and the construction method for removing the hub cofferdam in the removal of the hub cofferdam.

[0052] Compared with the prior art, the application has the following beneficial effects:

[0053] (1) The application selects the rope saw removal method as the construction method for removing the cofferdam unit below the normal water level, overcomes the difficulty in removing the cofferdam diaphragm wall with high strength, high steel content and high underwater volume, and successfully completes the segmentation, hoisting and removal of the largest single block of about 126 tons of diaphragm wall segmented blocks.

[0054] (2) The application provides a construction method for removing the hub cofferdam, overcomes the adverse effects of the water level change of the downstream section on the removal construction process, performs the construction in a smaller operable range, protects the newly built and built buildings and structures, and realizes the continuous navigation and non-closure construction.

[0055] (3) The application designs the lifting appliance, especially optimizes the material of the bottom rod pin shaft of the lifting appliance, breaks through the technical bottleneck of the design of the lifting appliance for hoisting the large-weight underwater diaphragm wall in the prior art, and successfully realizes the hoisting of the largest single block of about 126 tons of diaphragm wall segmented blocks in actual application. BRIEF DESCRIPTION OF DRAWINGS

[0056] Figure 1 is a schematic diagram of the upper structure in Example 1.

[0057] Figure 2 is a schematic diagram of the wall soil excavation in Example 1.

[0058] Figure 3 is a partial structure diagram of the diaphragm wall removal in Example 1.

[0059] Figure 4 is a position diagram of the drilling and hoisting holes and the cutting holes in the diaphragm wall, wherein the black circles represent the hoisting holes and the white circles represent the cutting holes.

[0060] Figure 5 is a schematic diagram of the upper structure in Example 2.

[0061] Figure 6 is a schematic diagram of the wall soil excavation in Example 2.

[0062] Figure 7 is a partial structure diagram of the diaphragm wall removal in Example 2.

[0063] Figure 8 is a schematic diagram of the upper structure in Example 3.

[0064] Figure 9 is a schematic diagram of the wall soil excavation in Example 3.

[0065] Figure 10 is a structural diagram of the diaphragm wall demolition part in Example 3.

[0066] Figure 11 is a unit division diagram of the upstream part hub cofferdam.

[0067] Figure 12 is a unit division diagram of the downstream part hub cofferdam.

[0068] Figure 13 is a schematic diagram of the lifting appliance structure described in Example 5.

[0069] Figure 14 is a schematic diagram of the lifting appliance internal structure described in Example 5.

[0070] Figure 15 is a schematic diagram of the front baffle assembly structure of the lifting appliance described in Example 5.

[0071] Figure 16 is a schematic diagram of the rear baffle assembly structure of the lifting appliance described in Example 5.

[0072] Figure 17 is a use state diagram of the lifting appliance described in Example 5.

[0073] Legend of reference signs: in Figures 13-17 , 1, first shaft, 2, second shaft, 3, first side plate, 4, second side plate, 5, front baffle assembly, 501, first baffle, 502, second baffle, 503, first partition plate, 6, rear baffle assembly, 601, third baffle, 602, fourth baffle, 603, second partition plate, 604, third partition plate, 7, lifting boom, 8, reinforcing rib assembly, 801, triangular partition plate, 802, fourth partition plate, 9, road surface, 10, backfill, 11, retaining wall, 12, coupling beam, 13 diaphragm wall, 14, diaphragm wall demolition block. DETAILED DESCRIPTION

[0074] The following non-limiting examples can make those skilled in the art more fully understand the present application, but do not limit the present application in any way. The following content is only an exemplary description of the scope of the present application, and those skilled in the art can make various changes and modifications to the application disclosed, which should also belong to the scope of the present application claimed.

[0075] Example 1

[0076] A method for demolishing a cofferdam unit, specifically as follows.

[0077] S1, demolish the superstructure, excavate and dredge the soil between the walls.

[0078] The upper structure in Example 1 is as shown in Figure 1

[0079] S101, break the pavement: 20cm thick concrete pavement is removed, and a hydraulic breaking hammer is used for breaking.

[0080] S102, excavate the backfill: the backfill is excavated in layers from high to low.

[0081] S103, break the retaining wall: in S102, the retaining wall on both sides is mechanically removed during the process of excavating the backfill in layers, and the retaining wall is reserved to be 50cm higher than the working surface inside the wall. During the removal, the work is evenly carried out in layers, and each layer is 2m. After the removal, the slag is cleaned in time, and the next layer is removed.

[0082] S104, break the coupling beam: after the upper structure of the coupling beam is removed, the 2m thick reinforced concrete coupling beam is broken by a hydraulic breaking hammer, and the exposed steel bars are cut by manual work. The removal direction is from left to right or from right to left in one direction, and the work is carried out from top to bottom.

[0083] In Example 1, the soil structure between the walls is as shown in Figure 2

[0084] S105, excavate and dredge the soil between the walls: land excavation combined with water excavation is used, in which two PC360 excavators are used to excavate (12000m3) at▽33.32m~▽38.32m, and 300t mud barges are used for water transportation. Two long-arm excavator ships + mud barge transportation are used to excavate (16000m3) at▽26.52m~▽33.32m, and the ground wall on both sides needs to be excavated deep and wide to leave a space for bottom cutting hole construction.

[0085] This step specifically includes the following processes:

[0086] 1. Use GPS measurement positioning, and the dredging depth is controlled according to the dredging display instrument.

[0087] 2. Excavate in layers. The layer thickness is 2m.

[0088] 3. The driver controls according to the dredging display instrument, the measuring personnel measure the depth of the water thallium, and the bucket depth is adjusted accordingly every 0.1m change in water level.

[0089] 4. Move forward after excavating one bucket, and move one ship position to the shore direction after excavating one ship position. The ship body movement must be accurately positioned to avoid missing excavation.

[0090] 5. To avoid backfilling, increase the dredging frequency for the last layer of dredging, and dredge and transport quickly. During the removal period, the project department regularly monitors the water depth of the temporary channel. If there is backfilling due to tidal changes, it will be treated.​​

[0091] 6. The mud barge should be fully loaded according to the excavated soil and the capacity of the dredger to avoid the phenomenon of "waiting for barge" or "work stoppage". The mud barge is strictly prohibited from leaking or running mud during the mud transportation process.

[0092] S2, adopting a rope saw process to remove the diaphragm wall, wherein the diaphragm wall is a double-row grid type reinforced concrete diaphragm wall. In Example 1, the structure of the diaphragm wall is as shown in Figure 3 The specific steps are as follows:

[0093] S210, dividing the diaphragm wall into cutting units. The diaphragm wall is divided into a plurality of cutting units, wherein the first cutting unit is divided in a trapezoidal structure with the upper part being wide and the lower part being narrow.

[0094] According to the lifting capacity of the lifting equipment, the size of the rope saw machine, and the actual situation on site, it is proposed to divide the cutting units in combination with the length of the divided diaphragm wall slot section. The male and female slots are separated by steel plates during the construction of the diaphragm wall, and the width of the two sequences of the slot section is 5m and 7m. The cutting is proposed to cut each slot section into 2 blocks. At the same time, in order to avoid cutting the slot at the partition steel plate, the left and right sides are each offset by 15cm from the female slot for cutting. Therefore, the standard division width is 2.65m and 3.35m (the first block and the last block removal unit. Considering safety during removal, the unit block is proposed to be reduced to 2m to reduce weight during removal. The removal of the deeper part can also consider reducing the length of the divided unit).

[0095] S220, drilling lifting holes.

[0096] Step S220 specifically includes steps S221-S225:

[0097] S221, determining the position of the lifting hole according to the size of the cutting unit in step S210, and lofting;

[0098] S222, connecting the hydraulic system placed on land with the drill pipe and track system supported on water by pipelines;

[0099] S223, fixing the drill pipe track on the surface of the diaphragm wall, and adjusting the perpendicularity and levelness of the track;

[0100] S224, operating the drill pipe console;

[0101] S225, taking out the core sample, protecting and marking the lifting hole.

[0102] S230, drilling cutting holes.

[0103] Step S230 specifically includes steps S231-S234:

[0104] S231, Dredging on both sides of the diaphragm wall. Divers confirm whether the dredging on both sides of the diaphragm wall meets the design requirements.

[0105] S232, Underwater positioning. The underwater drilling elevation is measured by the positioning bracket and the plummet dropped from the shore, and the depth is checked by the scale display through underwater observation. Meanwhile, the hole position is checked by the relative position between the drill holes, and the cutting drill rod is adjusted after the cutting hole position is determined through further measurement.

[0106] S233, Drilling with underwater assistance. After positioning, hydraulic drill bits are used for drilling, and it is necessary to ensure that the drilling tools are normally constructed and that the hole position does not deviate greatly.

[0107] S234, Installation of underwater directional wheel. After drilling, the diver removes the drill rod, and the shore personnel extract the drill machine to the shore. When subsequent cutting construction is carried out, underwater cooperation is carried out for rope saw chain hole drilling and underwater directional wheel installation and fixation.

[0108] The position of the lifting hole in step S220 and the cutting hole in step S230 is as shown in Figure 4 .

[0109] The lifting hole is arranged 1.2 m below the top of the diaphragm wall, and the horizontal position of the lifting hole is adjusted according to the width of the cutting groove section. The lifting hole is 0.8 m away from the edge for a 2.65 m groove section, and the lifting hole is 1.0 m away from the edge for a 3.35 m groove section. The diameter of the lifting hole is 140 mm.

[0110] The cutting hole is arranged at the position of the diaphragm wall 26.52, and is horizontally arranged at the cutting position of the groove section. The diameter of the cutting hole is 63 mm.

[0111] Specifically, the lifting hole is arranged 1.2 m below the top of the diaphragm wall, and the horizontal position of the lifting hole is adjusted according to the width of the cutting groove section. The lifting hole is 0.8 m away from the edge for a 2.65 m groove section, and the lifting hole is 1.0 m away from the edge for a 3.35 m groove section. The diameter of the lifting hole is 140 mm.

[0112] The cutting hole is horizontally arranged at the cutting position of the groove section. The diameter of the cutting hole is 63 mm.

[0113] S240, Cutting using a rope saw. The TD-370 crawler rope saw machine is mainly used for cutting on site, and the diamond string bead rope is mainly used for cutting. It is mainly composed of a battery, a rope saw frame, a driving wheel, a guide wheel and the like. The diamond string bead rope mainly uses sintered rope with a string diameter of 11.5 mm (concrete special type G22). The power of the rope saw machine is mainly driven by the motor to drive the driving wheel, and the driving wheel drives the rope to rotate to realize various cutting of concrete.

[0114] Step S240 specifically includes steps S241-S245

[0115] S241, the cutting platform ship is positioned;

[0116] S242, the cutting rope is passed underwater, and the rope head is taken back to the water surface. The diamond chain rope is sleeved at the rope saw machine main machine pulley, the underwater part is matched by the diver, the chain rope is taken to the underwater and then is sleeved into the bottom cutting hole from the outside to the inside, and then the two end chain rope heads are taken back to the water surface and are sleeved at the top of the cutting unit structure.

[0117] S243, the cutting rope is connected with the crawler cutting machine. After the required sawing path is formed, a free end is selected to twist a ring, different cutting materials require different twisting times of the rope, in order to avoid generating eccentric wear, generally, the initial twisting times are required to be 3-4 turns / m or more, under the condition that the equipment has been positioned and the universal wheel has been connected with the rope, the chain rope is appropriately tensioned and the rope head is mechanically connected by using the hydraulic clamp. When the cutting machine electric motor is started, the tension is adjusted by the control panel to lift the driving wheel, so that the diamond rope is appropriately taut, and then another electric motor is started to drive the driving wheel to drive the diamond rope to rotate and cut. The stability of the machine seat must be closely observed during the cutting process, and the deviation of the guide wheel is adjusted in time, so as to ensure that the cutting rope is in the same plane.

[0118] S244, vertical joints are cut. The first construction is the longitudinal and left-to-right cutting of the cutting unit, and the platform ship is parked in the first-line ship lock channel.

[0119] S245, the bottom transverse joint is cut. The cutting is performed from one side of the short section in the upstream to the downstream direction, the directional wheel is arranged at the cutting hole, the crawler rope saw machine is arranged on the top of the diaphragm wall, and the rope saw machine main machine pressure table air pressure display is combined with the underwater observation of the diver to judge whether the second cutting is completed.

[0120] S250, the cutting block is hoisted and broken and transported away. The hoisting and breaking of the cutting block are specifically that the cutting block is hoisted on shore by using the derrick crane ship, and the derrick crane ship is connected with the cutting block through a lifting tool.

[0121] In example 1, the top elevation of the diaphragm wall cutting block is △38.32 m, the bottom elevation of the upstream approach channel is △26.5 m, the wall height to be removed underwater is 38.32-26.5=11.82 m, the diaphragm wall thickness is 1.2 m, and the block length is 3.35 m. The volume of each cutting unit is 11.82*1.2*3.35=49.8 m3, and the weight of each cutting unit is about 126 tons according to the density of 2650 kg / m3 of reinforced concrete.

[0122] The water hoisting equipment to be used is a 300T ship crane (Dongguan Gong 0066 in Guangdong).

[0123] When the ship hoist hoists the cutting unit block, the operation area is within the ship lock channel range. From the ship body structure size and the channel width size, the channel meets the space requirements of ship operation (parking operation, turning); at the same time, the hoisted object (ground wall concrete cut block) is high, and the whole block must be vertically hoisted during hoisting (it is difficult to realize air turning); in the case of the same hoisted object weight, in order to ensure the safety of hoisting operation, the horizontal angle of the boom is not suitable to be small.

[0124] According to the display of the ship hoist lifting equipment, when the horizontal angle of the boom of the boom type crane ship is 70 degrees, the safe working load is 2940KN, and when the horizontal angle is 60 degrees, the safe working load is 2000KN>1260KN. The most unfavorable condition of the 300T ship hoist hoisting onshore is when it is lowered to the temporary wharf at the one-line ship lock longitudinal cofferdam side. According to experience, under this working condition, when the ship hoist boom is 60 degrees, the working radius is 16.7m, which meets the hoisting lowering requirements.

[0125] Embodiment 2

[0126] A cofferdam unit dismantling method is specifically as follows.

[0127] S1, dismantle the superstructure, excavate and dredge the soil between the walls.

[0128] In embodiment 2, the superstructure is as shown in Figure 5 .

[0129] S101, break the pavement: the 20cm thick concrete pavement is removed, and a hydraulic breaking hammer is used for breaking.

[0130] S102, excavate the backfill soil: excavate the backfill soil layer by layer from high to low.

[0131] S103, break and remove the retaining wall: in S102, the retaining wall on both sides is mechanically removed during the process of excavating the backfill soil layer by layer, and the retaining wall is reserved to be 50cm higher than the working surface in the wall. During the removal, the work is evenly carried out in layers, and each layer is 2m. After the removal is completed, the slag is cleaned in time, and the next layer of removal work is carried out.

[0132] S104, break and remove the beam: after the upper structure of the beam is removed, the 2m thick reinforced concrete beam is broken by a hydraulic breaking hammer, and the exposed steel bars are cut by manual work. The removal direction is one-way from left to right or from right to left, and the work is carried out from top to bottom.

[0133] In embodiment 2, the soil structure between the walls is as shown in Figure 6 .

[0134] S105, excavate and dredge the earthwork between the walls: this section is a grid-type diaphragm wall section, and the earthwork can only be excavated by a long-arm excavator. According to the grid-type diaphragm wall enclosure space, the grid is divided into blocks for excavation (partially blocked by the diaphragm wall, which cannot be excavated by a long-arm excavator, so a vertical arm is used for excavation). Due to the obstruction of the water inlet structure on both sides, the excavated earthwork (8553m3) needs to be transported once before being loaded onto the ship. At the same time, the diaphragm wall on both sides needs to be excavated deeper and wider to leave a space for the bottom cutting hole construction.

[0135] S2, using a rope saw process to remove the diaphragm wall, wherein the diaphragm wall is a three-row grid-type reinforced concrete diaphragm wall. In Example 2, the structure of the diaphragm wall is as shown in Figure 7 . The specific steps are as follows:

[0136] S210, divide the diaphragm wall into cutting units. The diaphragm wall is divided into multiple cutting units, and the first cutting unit is divided in a trapezoidal structure with the upper part being wider and the lower part being narrower.

[0137] According to the lifting capacity of the lifting equipment, the size of the rope saw machine, and the actual situation on site, it is proposed to divide the cutting units in combination with the length of the diaphragm wall groove section. The male and female grooves are separated by steel plates during construction, and the width of the two sequences is 5m and 7m. Each groove section is cut into 2 blocks. In order to avoid cutting the groove at the partition steel plate, the left and right sides are each offset by 15cm from the female groove. Therefore, the standard division width is 2.65m and 3.35m (the first and last blocks are removed units. Considering safety during removal, the unit block is reduced to 2m to reduce weight during removal. The removal of the deeper part can also consider reducing the length of the division unit).

[0138] S220, drill lifting holes.

[0139] Step S220 specifically includes steps S221-S225:

[0140] S221, determine the position of the lifting hole according to the size of the cutting unit in step S210, and loft;

[0141] S222, connect the hydraulic system placed on land with the drill pipe and track system supported on water with pipelines;

[0142] S223, fix the drill pipe track on the surface of the diaphragm wall, and adjust the verticality and horizontality of the track;

[0143] S224, use the drill pipe operation platform for operation;

[0144] S225, take out the core sample, protect and mark the lifting hole.

[0145] S230, drill cutting holes.

[0146] Step S230 specifically includes steps S231-S234:

[0147] S231, Dredging on both sides of the diaphragm wall. The diver confirms whether the dredging on both sides of the diaphragm wall meets the design requirements.

[0148] S232, Underwater positioning. The underwater drilling elevation is measured by the positioning bracket and the plummet dropped from the shore, and the depth is checked by the scale display through underwater observation. The hole position is also checked by the relative position between the drill holes. Further measurement is performed to adjust the cutting drill rod after the cutting hole position is determined.

[0149] S233, Drilling with underwater assistance. After positioning is completed, a hydraulic drill bit is used to drill a hole, and it is necessary to ensure that the drilling tool is normally constructed and that the hole position does not deviate greatly.

[0150] S234, Installation of underwater directional wheel. After drilling is completed, the diver removes the drill rod, and the shore personnel extract the drill machine to the shore. When subsequent cutting construction is performed, the underwater personnel cooperate to perform rope saw chain hole drilling and underwater directional wheel installation and fixation.

[0151] The positions of the lifting hole in step S220 and the cutting hole in step S230 are as shown in Figure 4 .

[0152] Specifically, the lifting hole is arranged 1.2 m below the top of the diaphragm wall, and the horizontal position of the lifting hole is adjusted according to the width of the cutting groove section. The lifting hole is 0.8 m away from the edge for a 2.65 m groove section, and the lifting hole is 1.0 m away from the edge for a 3.35 m groove section. The diameter of the lifting hole is 140 mm.

[0153] The cutting hole is horizontally arranged at the cutting position of the groove section. The diameter of the cutting hole is 63 mm.

[0154] S240, Cutting using a rope saw. The TD-370 crawler rope saw machine is mainly used for cutting on site, which is composed of a battery, a rope saw frame, a driving wheel, a guide wheel, etc. The diamond string bead rope mainly uses sintered rope with a bead diameter of 11.5 mm (concrete special type G22). The power of the rope saw machine is mainly provided by the motor directly driving the driving wheel, which drives the rope to rotate to achieve various cutting of concrete.

[0155] Step S240 specifically includes steps S241-S245

[0156] S241, Cutting platform ship is in position;

[0157] S242, underwater cutting rope, rope head back to the water. The diamond chain rope is sleeved at the rope saw machine main machine pulley, the underwater part is matched by the diver, the chain rope is sleeved into the bottom cutting hole from outside to inside after being taken to the underwater, and then the two end chain rope heads are taken back to the water and sleeved at the top of the cutting unit structure.

[0158] S243, the cutting rope is connected with the track cutting machine. After forming the required sawing path, a free end is selected to twist the ring, different cutting materials require different number of times of twisting the rope, in order to avoid generating bias grinding, generally the initial number of times of twisting the ring is required to be 3-4 turns / m or more, in the case that the equipment has been positioned and the universal wheel has been connected with the rope, the chain rope is appropriately tensioned and the rope head is mechanically connected by using the hydraulic clamp. When starting the cutting machine motor, the tension is adjusted by the control panel to ensure that the diamond rope is appropriately taut, and then the other motor is started to drive the driving wheel to drive the diamond rope to rotate and cut. The stability of the machine base must be closely observed during cutting, and the deviation of the guide wheel is adjusted in time to ensure that the cutting rope is in the same plane.

[0159] S244, cutting vertical joint. The first construction is the longitudinal and left-to-right cutting of the cutting unit, and the platform ship is parked in the ship lock channel.

[0160] S245, cutting bottom horizontal joint. From the short section side, the cutting is performed from the upstream to the downstream direction, the directional wheel is arranged at the cutting hole, the track rope saw machine is arranged on the top of the diaphragm wall, and moves with the cutting, and whether the second cutting is completed is judged by the air pressure display of the rope saw machine main machine pressure gauge and the underwater observation of the diver. Before cutting the bottom horizontal joint, the wedge-shaped steel plate gasket is driven into the vertical joint described in step S244.

[0161] S250, hoisting and cutting block, and crushing and transporting away. The hoisting and cutting block is specifically hoisting the cutting block on shore by using the derrick crane ship; the derrick crane ship is connected with the cutting block by the lifting tool.

[0162] In example 2, the top elevation of the diaphragm wall cutting block is △38.32 m, the bottom elevation of the upstream approach channel is △26.5 m, the wall height to be removed underwater is 38.32-26.5=11.82 m; the diaphragm wall thickness is 1.2 m; the block length is 3.35 m. The volume of each cutting unit is: 11.82×1.2×3.35=49.8 m3; the weight of a single cutting unit is about 126 tons according to the density of reinforced concrete of 2650 kg / m3.

[0163] The water hoisting equipment used is a 300T ship crane (Dongguan Gong 0066).

[0164] When the ship hoist hoists the cutting unit block, the operation area is within the ship lock channel range. From the ship body structure size and the channel width size, the channel meets the space requirements of ship operation (parking operation, turning); at the same time, the hoisted object (ground wall concrete cut block) is high, and the whole block must be vertically hoisted during hoisting (it is difficult to realize air turning); in the case of the same hoisted object weight, in order to ensure the safety of hoisting operation, the horizontal angle of the boom is not suitable to be small.

[0165] According to the display of the ship hoist lifting equipment, when the horizontal angle of the boom of the boom type crane ship is 70 degrees, the safe working load is 2940KN, and when the horizontal angle is 60 degrees, the safe working load is 2000KN>1260KN. The most unfavorable condition of the 300T ship hoist hoisting onshore is when it is lowered to the temporary wharf at the one-line ship lock longitudinal cofferdam side. Experience calculation, under this working condition, when the ship hoist boom is 60 degrees, the working radius is 16.7m, which meets the lowering requirements.

[0166] Example 3

[0167] A cofferdam unit dismantling method is specifically as follows.

[0168] S1, dismantle the superstructure, excavate and dredge the wall soil.

[0169] In example 3, the superstructure is as shown in Figure 8 .

[0170] S101, break the pavement: the 20cm thick concrete pavement is removed, and a hydraulic breaking hammer is used for breaking.

[0171] S102, excavate the backfill soil: excavate the backfill soil layer by layer from high to low.

[0172] S103, break and remove the retaining wall: in S102, the retaining wall on both sides is mechanically removed during the process of excavating the backfill soil layer by layer, and the retaining wall is reserved to be 50cm higher than the wall operation surface. During the removal, the operation is uniformly carried out layer by layer, and each layer is 2m. After the removal, the slag is cleaned in time, and the next layer of removal operation is carried out.

[0173] S104, break and remove the beam: after the removal of the beam upper structure, the 2m thick reinforced concrete beam is broken by a hydraulic breaking hammer, and the exposed steel bars are cut by manual operation. The removal direction is one-way from left to right or from right to left, and the construction is from top to bottom.

[0174] In example 3, the wall soil structure is as shown in Figure 9 .

[0175] S105, excavate and dredge the earthwork between the walls: the earthwork between the diaphragm walls is excavated by two PC360 excavators (7878 m3) from ▽20.0 m to ▽26.0 m, and excavator boats + mud barge transportation is used for excavation (3500 m3) from ▽18.32 m to ▽20.0 m.

[0176] S2, the diaphragm wall is removed by using a rope saw process, wherein the diaphragm wall is a double-row reinforced concrete diaphragm wall. In Example 3, the structure of the diaphragm wall is as shown in Figure 10 The specific steps are as follows:

[0177] S210, divide the diaphragm wall into cutting units. The diaphragm wall is divided into a plurality of cutting units, wherein the first cutting unit is divided in a trapezoidal structure with the upper part being wide and the lower part being narrow.

[0178] According to the lifting capacity of the lifting equipment, the size of the rope saw machine equipment, and combined with the actual situation on site, it is proposed to divide the cutting units in combination with the length of the diaphragm wall groove section. The male and female grooves are separated by steel plates during construction, and the width of the two sequences of the groove section is 5 m and 7 m. The cutting is proposed to be cut into 2 blocks for each groove section. At the same time, in order to avoid cutting the groove at the partition steel plate, the left and right sides are each outwardly offset by 15 cm from the female groove for cutting. Therefore, the standard division width is 2.65 m and 3.35 m (the first block and the last block removal unit, considering safety during removal, the unit block is proposed to be reduced to 2 m to reduce weight during removal, and the removal of the deep part can also consider reducing the length of the division unit).

[0179] S220, drill lifting holes.

[0180] Step S220 specifically includes steps S221-S225:

[0181] S221, determine the lifting hole position according to the size of the cutting unit in step S210, and lofting;

[0182] S222, connect the hydraulic system placed on land with the drill pipe and track system supported on water by pipelines;

[0183] S223, fix the drill pipe track on the surface of the diaphragm wall, and adjust the perpendicularity and levelness of the track;

[0184] S224, operate using the drill pipe operation platform;

[0185] S225, take out the core sample, protect and mark the lifting hole.

[0186] S230, drill cutting holes.

[0187] Step S230 specifically includes steps S231-S234:

[0188] S231, Dredging on both sides of the diaphragm wall. The diver confirms whether the dredging on both sides of the diaphragm wall meets the design requirements.

[0189] S232, Underwater positioning. The underwater hole elevation is measured by the positioning bracket and the sinker dropped from the shore, and the depth is checked by underwater observation using the scale. Meanwhile, the hole position is checked by the relative position between the holes, and the cutting drill rod is adjusted after the cutting hole position is determined by further measurement.

[0190] S233, Drilling with underwater assistance. After positioning, hydraulic drill bit is used for drilling, and it is necessary to ensure that the drilling tool is normal during construction and the hole position does not deviate greatly.

[0191] S234, Installation of underwater directional wheel. After drilling, the diver removes the drill rod, and the shore personnel extract the drill machine to the shore. When subsequent cutting construction is carried out, underwater cooperation is carried out for rope saw chain hole and underwater directional wheel installation and fixation.

[0192] The position of the lifting hole in step S220 and the cutting hole in step S230 is as shown in Figure 4 .

[0193] Specifically, the lifting hole is arranged 1.2 m below the top of the diaphragm wall, and the horizontal position of the lifting hole is adjusted according to the width of the cutting groove section. The lifting hole is 0.8 m away from the edge for a 2.65 m groove section, and the lifting hole is 1.0 m away from the edge for a 3.35 m groove section. The diameter of the lifting hole is 140 mm.

[0194] The cutting hole is horizontally arranged at the cutting position of the groove section. The diameter of the cutting hole is 63 mm.

[0195] S240, Cutting with rope saw. The TD-370 crawler rope saw machine is mainly used for cutting on site, which is composed of battery, rope saw frame, driving wheel, guide wheel and other components. The diamond string bead rope mainly uses sintered rope with a bead diameter of 11.5 mm (concrete special type G22). The power of the rope saw machine is mainly driven by the motor to drive the driving wheel, which drives the rope to rotate to realize various cutting of concrete.

[0196] Step S240 specifically includes steps S241-S245

[0197] S241, Cutting platform ship in position;

[0198] S242, Cutting rope underwater, rope head back to water surface. The diamond chain rope is sleeved at the rope saw machine main machine pulley, and the underwater part is cooperated by the diver to bring the chain rope to the underwater, and then the chain rope is sleeved into the bottom cutting hole from the outside to the inside, and then the two end chain rope heads are brought back to the water surface and sleeved at the top of the cutting unit structure.

[0199] S243, the cutting rope is connected with the track cutting machine. After forming the required sawing path, a free end is selected to twist the ring. Different cutting materials require different number of twists for the rope. To avoid uneven wear, the initial number of twists is generally required to be 3-4 turns / m or more. In the case where the equipment is already in place and the universal wheel is connected to the rope, the chain rope is appropriately tensioned and the rope head is mechanically connected by the hydraulic clamp. When starting the cutting machine motor, adjust the driving wheel tension by the control panel to ensure that the diamond rope is properly taut. Then start the other motor to drive the driving wheel to rotate the diamond rope for cutting. The stability of the machine seat must be closely observed during cutting, and the deviation of the guide wheel must be adjusted in time to ensure that the cutting rope is in the same plane.

[0200] S244, cutting vertical joints. The first construction is the longitudinal and left-to-right cutting of the cutting unit. The platform ship is parked in the ship lock channel.

[0201] S245, cutting the bottom transverse joint. From the short section side, cut from upstream to downstream. Set the directional wheel at the cutting hole, and place the track rope sawing machine on the top of the diaphragm wall. As the cutting progresses, move the rope sawing machine, and through the pressure gauge air pressure display of the rope sawing machine main machine and the observation of the diver underwater to determine whether the second cutting is completed. Before cutting the bottom transverse joint, the wedge-shaped steel plate gasket is driven into the vertical joint described in step S244.

[0202] S250, hoisting and cutting blocks, and crushing and transporting away. The hoisting and cutting block is specifically using a derrick crane to hoist the cutting block onto the shore; the derrick crane is connected to the cutting block through a sling.

[0203] In Example 3, the sling calculation is carried out according to the relevant working conditions. The top elevation of the downstream removal block is △ 26.0 m, the bottom elevation of the downstream approach channel is △ 19.32 m, and the wall height to be removed underwater is 26-18.32 = 7.68 m. The diaphragm wall is 1.2 m thick, and the block length is 3.35 m. The volume of each cutting unit is: 7.68 x 1.2 x 3.35 = 49.8 m3; the density of reinforced concrete is 2650 kg / m3, so the weight of a single cutting unit is about 82 tons. The lifting load of the 200t floating crane is shown in the following figure

[0204] The water hoisting equipment used is a 200T ship crane (Dongguan Gong 0066).

[0205] When the ship hoists the cutting unit block, the operation area is within the ship lock channel range. From the ship body structure size and the channel width size, the channel meets the space requirements of ship operation (parking operation, turning); at the same time, the hoisted object (diaphragm wall concrete cutting block) is high, and it must be vertically hoisted as a whole (it is difficult to turn in the air) during hoisting; in the case of the same hoisted object weight, in order to ensure the safety of hoisting operation, the horizontal angle of the boom should not be too small.

[0206] The 200t floating crane hoists the 3m long, 1.2m thick and 11.8m high diaphragm wall removal block, the 33m arm length, the 45° arm rod angle, the 23.4m horizontal working distance, the 25.26m hoisting height, the actual hoisting 106t, the hoisting capacity 110t, the hoisting load rate 96%, which can meet the construction requirements.

[0207] Example 4

[0208] A construction method for removing a hub cofferdam, comprising the following steps.

[0209] T1, dividing the upstream part and the downstream part of the cofferdam into cofferdam units respectively;

[0210] T2, simultaneously removing the cofferdam units of the upstream part and the downstream part in step T1.

[0211] In step T1, the cofferdam units are divided in the following manner: Figure 11 (upstream part), Figure 12 (downstream part).

[0212] In the cofferdam S1 unit to the cofferdam S6 unit, Figure 11 the cofferdam units are removed according to the construction method for removing the cofferdam units in Example 1; Figure 11 the cofferdam units in the cofferdam S7 unit to the cofferdam S12 unit are removed according to the construction method for removing the cofferdam units in Example 2; Figure 12 the cofferdam units in the cofferdam X10 unit to the cofferdam X14 unit are removed according to the construction method for removing the cofferdam units in Example 3.

[0213] The removal of the underground continuous wall cofferdam is divided into two working faces, the upstream and the downstream, which are independent and do not interfere with each other. Spatially, the removal of the underground continuous wall cofferdam is in the order of top to bottom, first the partition plate and then the main wall, and the removal is strictly divided according to the groove section of the diaphragm wall.

[0214] 1. Upstream section: the removal sequence of the upper pavement structure, the retaining wall structure, the backfill soil between the retaining walls and the coupling beam is from S1 to S11, and the coupling beam top is used as a construction road for waste transportation. The lower diaphragm wall structure is removed by rope sawing from S1, and multiple working faces are removed to S11 section. The soil between the diaphragm walls is excavated and cleaned by a long-arm excavator ship + transport barge.

[0215] 2, downstream section: upper pavement structure, retaining wall structure, backfill between retaining walls and coupling beam removal sequence from X14 to X10, using the coupling beam top as a construction road for waste disposal, part of which cannot be directly landed by using excavator ship + transport barge to excavate and land. The lower diaphragm wall structure is removed by rope saw from X14, and multiple working surfaces are removed to X10 section. The soil between the diaphragm walls is excavated and cleaned by long-arm excavator ship.

[0216] 3, cofferdam diaphragm wall removal: prerequisite completion → pavement structure mechanical breaking → soil excavation between retaining walls → mechanical breaking and excavation of plain concrete retaining wall on both sides → diaphragm wall hoisting hole drilling → mechanical removal of reinforced concrete coupling beam and exposed steel bar cutting → underwater excavation of soil between diaphragm walls → underwater cutting hole drilling → erection of rope saw construction platform → main diaphragm wall cutting, hoisting and landing removal → diaphragm wall cutting and landing removal.

[0217] Among them, the prerequisites for the removal of the cofferdam diaphragm wall are as follows:

[0218] 1, The underground continuous wall cofferdam serves as the upstream and downstream construction road, and the upper structure can be removed only after the main structure, metal structure and mechanical and electrical equipment installation are completed.

[0219] 2, The upstream underground continuous wall cofferdam serves as the hub left and right bank external traffic, and the upper structure can be removed only after the completion of the construction of the top traffic bridge and the opening to traffic, ensuring smooth traffic on both banks.

[0220] 3, The downstream underground continuous wall cofferdam serves as the only downstream construction road, and the upper structure of the downstream diaphragm wall removal section can be removed only after the completion of the construction of the pier structure and the inter-pier plate at the transverse soil cofferdam of the downstream key line.

[0221] Example 5

[0222] The lifting tool for lifting the diaphragm wall in Examples 1-4 has the structure shown in Figures 13-17 .

[0223] As shown in Figure 13 , the present embodiment provides a diaphragm wall removal block lifting tool, which comprises two structural members arranged opposite to each other, and the two structural members are structurally identical; a first shaft 1 and a second shaft 2 are arranged between the two structural members, and the first shaft 1 is arranged above the second shaft 2; the structural member comprises a first side plate 3 and a second side plate 4, the upper end of the first side plate 3 and the upper end of the second side plate 4 are connected by a lifting rod 7, and the outer side surface of the first side plate 3 and the outer side surface of the second side plate 4 are both provided with a pad, and the lifting rod 7 is arranged through the pad; a front baffle assembly 5 is arranged between the first side plate 3 and the second side plate 4, the back of the front baffle assembly 5 is provided with a rear baffle assembly 6, and the lower part of the rear baffle assembly 6 is provided with a reinforcing rib assembly 8.

[0224] As shown in Figure 14 , the first shaft 1 passes through the back baffle assembly 6 of one structure, the front baffle assembly 5 of the other structure and the front baffle assembly 5 of the other structure, the back baffle assembly 6 of one structure in turn. The second shaft 2 passes through the front baffle assembly 5 of one structure, the front baffle assembly 5 of the other structure in turn. The length of the first shaft 1 is greater than that of the second shaft 2, and both the first shaft 1 and the second shaft 2 are cap screws.

[0225] As shown in Figure 15 , the front baffle assembly 5 comprises a first baffle 501 and a second baffle 502 arranged in parallel and spaced apart, and a plurality of first partitions 503 connecting the first baffle 501 and the second baffle 502. The plurality of first partitions 503 are arranged horizontally and vertically spaced apart. The first baffle 501 and the second baffle 502 are provided with a waist hole for the first shaft 1 to pass through and a through hole for the second shaft 2 to pass through, and a gasket is arranged outside the through hole for the second shaft 2 to pass through.

[0226] As shown in Figure 16 , the back baffle assembly 6 comprises a third baffle 601 and a fourth baffle 602 arranged in parallel and spaced apart, a plurality of second partitions 603 arranged horizontally between the third baffle 601 and the fourth baffle 602, and a plurality of third partitions 604 arranged vertically between the third baffle 601 and the fourth baffle 602. The two sides of the back baffle assembly 6 are respectively connected with the first side plate 3 and the second side plate 4, the front side of the back baffle assembly 6 is connected with the rear side of the front baffle assembly 5, and the upper side of the back baffle assembly 6 is flush with the upper side of the front baffle assembly 5.

[0227] As shown in Figure 13 , the reinforcing rib assembly 8 comprises a plurality of triangular partitions 801 arranged in the horizontal direction, and a fourth partition 802 arranged between the plurality of triangular partitions 801.

[0228] The first shaft 1 and the second shaft 2 are made of mixed materials of 45 steel and 40Cr steel and are quenched and tempered, and the remaining steel plates are made of Q355B material; the diameter of the first shaft 1 is 100 mm, and the diameter of the second shaft 2 is 115 mm. As shown in Figure 17 , when in use, two lifting holes are formed above the diaphragm wall removal block 14, two lifting lugs are used, and the two second shafts 2 are respectively arranged in the two lifting holes, and the lifting equipment is connected through the lifting rod 7.

[0229] Application example

[0230] In the process of hoisting the diaphragm wall cutting block of the cofferdam, the bottom pin shafts of Examples 6 and Comparative Examples 1-4 are respectively applied to the lifting device described in Example 5 to hoist the diaphragm wall cutting block. It is verified in practice that the lifting device composed of the bottom pin shaft prepared in Example 6 successfully hoists and removes the diaphragm wall cutting block of about 126 tons, and the stress is more uniform and safer; Comparative Examples 1-3 cannot achieve hoisting and removal of the diaphragm wall cutting block of about 126 tons.

[0231] Comparative Example 1

[0232] Compared with Example 1, steps S244 and S245 are changed to cut the bottom transverse seam first, and then cut the longitudinal seam, and the rest are the same.

[0233] In the actual project involved in the present application, the diaphragm wall cutting engineering quantity is large, and the upstream removal position is about 300 meters, and the downstream is about 180 meters. If the construction method of cutting the transverse seam first and then cutting the vertical seam is adopted, only single block cutting can be achieved. The diaphragm wall is constructed in a public slot and a mother slot, and the public slot and the mother slot are connected by an I-shaped steel plate to stop water, and the I-shaped steel plate is only welded with the mother slot and is not welded with the public slot. If the transverse seam is cut in advance, only the friction force between the concrete and the steel plate supports the two cutting blocks, which has the risk of collapse. If the vertical seam is cut first, multiple cutting devices can be used to cut vertically at different positions at the same time, the diaphragm wall is divided in advance, and the divided block will not fall when the transverse seam of the diaphragm wall is not cut (most of the diaphragm wall is still under the riverbed, and only the part above the riverbed is removed). The vertical seam cutting in advance can greatly save the construction period.

[0234] Comparative Example 2

[0235] The commercially available lifting device with clamps and beam type lifting device are used for diaphragm wall removal construction.

[0236] In the actual project involved in the present application, it is found that the use of lifting device with clamps and beam type lifting device for diaphragm wall removal construction has the following disadvantages:

[0237] 1. The clamps are generally locked by the self-weight of the hoisted object, and the lifting load has limitations. At the same time, the surface concrete of the diaphragm wall is uneven, and there is no fixed position to use the clamps to lock, so it cannot meet the requirements of the cutting block of the project. Moreover, when the cutting block is lowered, an inclination angle is formed with the ground, and the stress of the clamps themselves will change during this process, and the locking degree of the clamps will also change, which has a great risk.

[0238] 2. Beam-type lifting slings typically consist of a lifting array, dividing the sling into multiple evenly distributed stress points for lifting. Generally, slings or wire ropes are needed to connect the sling and the load. In this project, the load to be lifted is a diaphragm wall cutting block, which cannot be lifted by drilling multiple holes in the wall (too many holes could easily cause the wall to break along the drilled holes). Furthermore, the cutting block will form an angle with the ground when lowered, at which point the slings will easily become under stress on one side, requiring very high sling strength.

[0239] 3. The width of the diaphragm wall cutting block is 1.2m. The hoisting equipment needs to be locked to the wall for fixation. It is difficult to find commercially available hoisting equipment with the right size to meet the requirements.

[0240] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A construction method for dismantling a cofferdam unit, characterized in that, The cofferdam unit is a cofferdam unit below the normal water level; Includes the following steps: S1. Demolish the superstructure, excavate and dredge the soil between the walls; S2. Use wire sawing to demolish the diaphragm wall; The diaphragm wall mentioned in step S2 includes at least one of double-row reinforced concrete diaphragm wall, double-row grid-type reinforced concrete diaphragm wall, and triple-row grid-type reinforced concrete diaphragm wall. Step S2 includes the following steps: S210. Divide the diaphragm wall into cutting units; S220. Drill hoisting holes; S230. Drill cutting holes; S240. Cut using a wire saw; S250. Hoist the cut blocks, break them up, and remove them; Step S230 includes the following steps: S231. Dredging both sides of the diaphragm wall; S232. Underwater positioning; S233. Drilling with underwater assistance; S234. Installing underwater directional wheels; Step S240 includes the following steps: S241. The cutting platform vessel is positioned; S242. The cutting rope is threaded underwater, and the rope end is brought back to the surface; S243. The cutting rope is connected to the track cutting machine; S244. The vertical seam is cut; S245. The bottom horizontal seam is cut. Steps S244 and S245 are performed sequentially. In step S245, during the process of cutting the bottom transverse seam, the wedge-shaped steel plate shim is driven into the already cut part of the bottom transverse seam. In step S250, the lifting of the cutting block specifically involves using a boom-type crane vessel to lift the cutting block ashore; the boom-type crane vessel is connected to the cutting block via a lifting device; the lifting device includes two opposing structural members, with a first shaft (1) and a second shaft (2) passing through the two structural members; the lifting device includes a first side plate (3) and a second side plate (4), with the upper end of the first side plate (3) and the upper end of the second side plate (4) connected by a boom (7); a front baffle assembly (5) is provided between the first side plate (3) and the second side plate (4), a rear baffle assembly (6) is provided on the back of the front baffle assembly (5), and a reinforcing rib assembly (8) is provided below the rear baffle assembly (6); the first shaft (1) passes sequentially through the rear baffle assembly (6) and the front baffle assembly (5) of one structural member and the front baffle assembly (5) and the rear baffle assembly (6) of the other structural member; the second shaft (2) passes sequentially through the front baffle assembly (5) of one structural member and the front baffle assembly (5) of the other structural member.

2. The construction method for dismantling a cofferdam unit according to claim 1, characterized in that, In step S1, the superstructure includes the road surface, backfill, retaining wall, and connecting beam.

3. The construction method for dismantling a cofferdam unit according to claim 1, characterized in that, Step S210 specifically involves: The diaphragm wall is divided into multiple cutting units, wherein the first cutting unit is divided into a trapezoidal structure that is wider at the top and narrower at the bottom.

4. The construction method for dismantling a cofferdam unit according to claim 1, characterized in that, In step S210, each of the cutting units has two lifting holes.

5. The construction method for dismantling a cofferdam unit according to claim 1, characterized in that, Step S220 includes the following steps: S221. Determine the position of the lifting hole according to the size of the cutting unit described in step S210, and lay out the layout; S222. Connect the land-based hydraulic system to the drill rod and track system supported on the water using pipelines; S223. Fix the drill rod track to the surface of the diaphragm wall and adjust the verticality and horizontality of the track; S224. Use the drill pipe control panel for operation; S225. Remove the core sample and protect and mark the lifting hole.

6. The construction method for dismantling a cofferdam unit according to claim 1, characterized in that, The first shaft (1) and the second shaft (2) are made of a mixture of 45 steel and 40Cr steel; the structural components are made of Q335B steel.

7. A construction method for dismantling a cofferdam unit according to any one of claims 6, characterized in that, The first shaft (1) and the second shaft (2) are prepared by a modulated heat treatment forming method.

8. A construction method for dismantling a cofferdam for a key project, characterized in that, Includes the following steps: T1. Divide the upstream and downstream demolition sections of the cofferdam into cofferdam units; T2. The cofferdam unit described in step T1 is dismantled; The construction method for dismantling the cofferdam unit in step T2 is selected from any one of the construction methods for dismantling a cofferdam unit according to claims 1-7.

9. A construction method for dismantling a cofferdam according to claim 8, characterized in that, In step T2, the dismantling of the cofferdam unit specifically involves simultaneously dismantling the upstream dismantling portion of the cofferdam unit as described in step T1 and dismantling the downstream dismantling portion of the cofferdam unit as described in step T1.

10. A construction method for dismantling a cofferdam according to claim 9, characterized in that, In step T2, the top of the connecting beam is used as a construction road for waste disposal.

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