Underwater excavation device for deep foundation pit in water-rich stratum and construction method

Abstract

The invention discloses a deep foundation pit underwater excavation device for a water-rich stratum and a construction method, the deep foundation pit underwater excavation device for the water-rich stratum comprises an enclosure assembly and a foundation pit underwater excavation assembly, the enclosure assembly comprises an underground diaphragm wall arranged in the stratum, a steel frame arranged on the underground diaphragm wall and supporting bodies arranged on the steel frame, and supporting steel pieces are arranged between the supporting bodies; the movable construction assembly comprises a movable track arranged above the underground diaphragm wall, a movable track car arranged on the movable track and a working track car arranged on the movable track car; according to the foundation pit underwater excavation device, foundation pit underwater excavation is achieved, precipitation is not needed in the excavation process, the influence of underground water changes on engineering can be ignored, and protection of the surrounding environment of the foundation pit is very beneficial. The water pressure in the foundation pit provides supporting force for the foundation pit support structure, the problem in the construction process of the deep foundation pit in the water-rich stratum is solved through a self-balancing technology, the construction quality and safety reliability are improved, and the construction cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of foundation and substructure engineering, and in particular to an underwater excavation device and a construction method for a deep foundation pit in a water-rich stratum. Background Art

[0002] With the acceleration of urbanization in my country, the shortage of construction land and traffic congestion have become obstacles to the development of modern cities, making major cities in my country focus on tunnels and underground projects. The traditional foundation pit excavation construction technology is faced with deep foundation pit projects with abundant groundwater and high pressure water head such as near rivers and rivers. The excavation method is to lower the groundwater level by laying foundation pit dewatering wells, so that the water head in the pit is lower than the excavation surface, thereby completing the foundation pit excavation. However, for many projects, the complex geological conditions have led to the use of suspended water-stop curtains in the foundation pit design. There is no way to completely block the hydraulic connection between the inside and outside of the foundation pit, which puts high demands on the dewatering work of the foundation pit. On the one hand, for projects with complex surrounding environments, the dewatering height should be strictly controlled to prevent the water level from dropping too much and affecting the surrounding environment; on the other hand, during the construction of the foundation pit, water gushing and sand flow problems often occur due to the failure to properly treat the groundwater, which poses a safety hazard and is difficult to effectively ensure the quality of the project.

[0003] Therefore, it is necessary to develop an underwater excavation device and construction method for deep foundation pits in water-rich strata. The underwater excavation construction process of deep foundation pits can ignore the impact of groundwater changes on the project because the water head inside and outside the pit is consistent. This is very beneficial to the protection of the environment around the foundation pit. For some projects with strict deformation control requirements, the method of using the water head inside the pit to be higher than the water head outside the pit can be used to control the deformation of the foundation pit, thereby increasing the safety and reliability of the construction. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the above-mentioned problems existing in the existing underwater excavation devices and construction methods for deep foundation pits in water-rich strata, the present invention is proposed.

[0006] Therefore, the object of the present invention is to provide an underwater excavation device and construction method for deep foundation pits in water-rich strata.

[0007] To solve the above technical problems, the present invention provides the following technical solutions: an underwater excavation device for deep foundation pits in water-rich strata, comprising: a retaining assembly, including a ground-connected wall arranged in the stratum, a steel frame arranged on the ground-connected wall, and a support body arranged on the steel frame, wherein support steel parts are arranged between the support bodies; a movable construction assembly, including a movable track arranged above the ground-connected wall, a movable rail car arranged on the movable track, and a working rail car arranged on the mobile rail car; and a working assembly, including a leveling component and a stirring and suction component arranged on the working rail car, wherein the stirring and suction component is used for excavating the foundation pit, discharging mud and bottom grouting, and the leveling component performs leveling after the stirring and suction component is working.

[0008] As a preferred solution of the underwater excavation device for deep foundation pits in water-rich strata described in the present invention, the stirring and suction component includes a pipe body arranged on a working rail vehicle, a water inlet pipe arranged in the pipe body, a water outlet pipe arranged in the pipe body and a grouting pipe, a stirring and suction head is provided at the lower end of the pipe body, and the stirring and suction head includes a limiting plate detachably connected to the pipe body, a rotating cutter head arranged at the lower end of the limiting plate, and a driving member arranged at the lower end of the pipe body for driving the rotating cutter head to rotate, and the width of the limiting plate is greater than the width of the rotating cutter head.

[0009] As a preferred solution of the underwater excavation device for deep foundation pits in water-rich strata described in the present invention, wherein: a curved conduit is provided between the ground-connected walls, the curved conduit is in a concave arch shape as a whole, a grouting leak is provided on the curved conduit, the grouting leak is evenly arranged along the curved conduit, the distance between the edge of the grouting leak and the edge of the pit is not greater than the grouting diffusion radius, the distance between every two adjacent grouting leaks and the adjacent straight pipe part of the curved conduit is not greater than twice the grouting diffusion radius, pipe connecting ports are provided at both ends of the curved conduit, the pipe connecting ports are connected to the grouting pipe, and a plurality of connecting steel plates corresponding to the support body and adjacent curved conduits are provided around the curved conduit.

[0010] As a preferred solution of the underwater excavation device for deep foundation pits in water-rich strata described in the present invention, the support body includes a support bracket arranged on a supporting steel member and a diagonal support plate arranged below the support bracket, a plurality of the support bodies are equidistantly arranged along the length direction of the steel frame, the support bracket is filled with foam boards, and the transverse steel bars in the ground-connected wall steel cage at the support body are reasonably thickened and densely arranged according to the design.

[0011] As a preferred solution of the underwater excavation device for deep foundation pits in water-rich strata of the present invention, the supporting steel member comprises a movable end, a fixed end and a plurality of intermediate sections fixedly connected between the movable end and the fixed end, the movable end is provided with a self-locking hydraulic jack and a stop block, and the stop block is stuck in the gap formed by the movable end; A limiting hole is provided at the upper end of the anti-retraction block, a limiting rod is provided in the limiting hole, an electric winder, a steel wire and a slider are provided in the anti-retraction block, and the edge of the slider is wavy, and the slider is connected to the electric winder through the steel wire; a pressure sensor for measuring the axial pressure of the self-locking hydraulic jack is provided in the fixed end.

[0012] As a preferred solution of the underwater excavation device for deep foundation pits in water-rich strata described in the present invention, the leveling component includes a conveying pipe detachably connected to the working rail vehicle and a leveling head arranged at the lower end of the conveying pipe, a leveling drive component for controlling the operation of the leveling head is provided in the conveying pipe, and a GPS positioning module is provided on the leveling head.

[0013] The present invention also includes an underwater excavation construction method for an underwater excavation device for a deep foundation pit in a water-rich stratum: Review the measurement reference points and reference lines of the target location, and measure the location of the ground-connected wall to the site according to the designed ground-connected wall coordinates, and mark them at the same time; Dig the guide trench and pour the concrete guide wall. Use the trenching machine to dig out the trench of the underground continuous wall. Weld the support body on the steel frame where the supporting steel parts are located, fill the supporting bracket with foam board, hoist and lower the steel cage welded with the steel frame, and then pour the underground continuous wall concrete. Excavate and construct the first concrete support. After excavating to the groundwater level, inject water into the pit to keep the water level inside and outside the foundation pit consistent. Set up movable construction components and install stirring and suction components on the trolley to continue excavating while pumping out the slurry. During the subsequent construction process, monitor the changes in the water level in the pit at all times to keep the water level inside and outside the pit consistent. After excavating to the designed position of the second supporting steel member, remove the foam board filled on the supporting bracket and clean the supporting bracket, install anti-falling facilities on the supporting bracket, fix it to the ground wall with expansion bolts, and then slowly hoist the assembled supporting steel member to the designed position, and install the remaining supporting steel members in sequence; Excavate to the bottom of the foundation pit and trim the bottom into a concave arch shape, install and lower the curved guide pipe, continue to cast the bottom, and use the leveling components to level it, and slowly drain the water in the foundation pit, always observe the pressure value measured by the pressure sensor and adjust the hydraulic jack in time to ensure that the thrust is balanced with the soil pressure; Carry out the main structure construction, remove the lowest supporting steel parts after the construction of the side walls and the bottom plate is completed and the concrete reaches the required strength, remove the middle supporting steel parts after the construction of the side walls and the middle plate is completed and the concrete reaches the required strength, backfill the space between the side walls and the ground-connected walls with cement stone powder slag, finally remove the first concrete support after the construction of the side walls and the top plate is completed, complete the removal of all supports, and backfill the remaining space between the side walls and the ground-connected walls with cement stone powder slag.

[0014] As a preferred solution of the underwater excavation construction method for deep foundation pit in water-rich strata described in the present invention, the above steps also include: When the first concrete support is blocked by the support steel installation, an underwater frogman is used to tie a traction rope on the support, and the support is towed to the corresponding support bracket with the help of the construction platform; the self-locking hydraulic jack at the movable end of the support steel is used to timely apply prestress to the support steel in stages, and the hydraulic jack is locked after the prestress reaches the design value measured by the pressure sensor at the fixed end, and the underwater frogman is used to put a stop block in the gap formed in the middle of the movable end, and a limit rod is inserted into the limit hole and welded to prevent prestress loss. Finally, the lifting wire rope is untied, and anti-falling measures for the support steel are set with steel plates and wire ropes.

[0015] As a preferred solution of the underwater excavation construction method for deep foundation pits in water-rich strata described in the present invention, if it is difficult to install underwater support steel parts, the underwater installation sequence can be to install some key support steel parts first, and the support steel parts that have not been installed at the remaining design positions can be installed after the water level is lowered to the corresponding positions.

[0016] As a preferred embodiment of the underwater excavation device and construction method for deep foundation pits in water-rich strata described in the present invention, when water in the foundation pit is slowly evacuated and leakage occurs, water is promptly injected into the pit to above the leakage port, and then a small boat is used to assist in anti-seepage measures.

[0017] Beneficial effects of the present invention: In the present invention, the support body used to support the support steel member is pre-firmly welded to the steel frame of the enclosure assembly, and the steel frame is pre-welded to the steel cage in the ground-connected wall, which reduces the subsequent construction workload and greatly improves the construction efficiency.

[0018] The supporting steel parts of the present invention are equipped with self-locking hydraulic jacks, pressure sensors and stop slide blocks, which can ensure that the supporting steel parts can effectively stop and have self-locking functions, and prevent the loss of prestress when the hydraulic jack fails. The supporting steel parts can be monitored by the pressure sensor at all times to determine the supporting working state, and then the supporting axial force can be adjusted through the hydraulic structure to effectively support the foundation pit.

[0019] The stirring and suction component of the present invention is installed on a movable construction component, and the foundation pit excavation and mud discharge can be carried out simultaneously. In addition, a grouting pipe is provided, and the subsequent bottom sealing grouting can also be closely connected, which greatly improves the work efficiency and reduces the construction cost.

[0020] The curved conduit during the bottom sealing of the present invention can ensure uniform grouting, and appropriately reducing the distance between the grouting leaks on the curved conduit can increase the grouting speed. After the grouting is completed, the curved conduit is left in the concrete to reinforce it, which greatly improves the anti-uplift stability of the pit bottom. The bottom sealing concrete is in a concave arch shape with a large middle and thin sides, which conforms to the stress form of the pit bottom and effectively improves the strength of the bottom sealing concrete.

[0021] The present invention realizes underwater excavation of foundation pits. During the excavation process, no precipitation is required, and the influence of groundwater changes on the project can be ignored, which is very beneficial to the protection of the surrounding environment of the foundation pit. The water pressure in the foundation pit provides support for the foundation pit retaining structure, and a "self-balancing" process is used to solve the difficulties in the construction process of deep foundation pits in water-rich strata, improve construction quality and safety reliability, and reduce project costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them: Figure 1 The present invention is an overall structural diagram of the underwater excavation device for deep foundation pits in water-rich strata.

[0023] Figure 2 The figure is a position diagram of a curved conduit used in an underwater excavation device for a deep foundation pit in a water-rich stratum according to the present invention.

[0024] Figure 3 The invention is a cross-sectional view of a foundation pit of an underwater excavation device for a deep foundation pit in a water-rich stratum.

[0025] Figure 4 The invention is an underwater excavation device for deep foundation pit in water-rich strata Figure 3 Enlarged view of part A.

[0026] Figure 5 This is a diagram of the supporting steel parts of the underwater excavation device for a deep foundation pit in a water-rich stratum according to the present invention.

[0027] Figure 6 The present invention is a cross-sectional view of supporting steel parts of an underwater excavation device for a deep foundation pit in a water-rich stratum.

[0028] Figure 7 The present invention is a structural diagram of a stop block of an underwater excavation device for a deep foundation pit in a water-rich stratum.

[0029] Figure 8 The present invention is a symbol diagram of anti-heave safety factor parameters for the underwater excavation construction method of a deep foundation pit in a water-rich stratum. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0031] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0032] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0033] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included. Example 1

[0034] Reference Figure 1-7 , which is the first embodiment of the present invention, provides an underwater excavation device for deep foundation pits in water-rich strata, the device comprising: a containment assembly 100. In this embodiment, the containment assembly 100 comprises a ground-connected wall 101 arranged in the stratum, the ground-connected walls 101 are closely arranged in sequence along the length direction of the foundation pit, a steel frame 102 and a support body 103 arranged on the steel frame 102 are provided on the ground-connected wall 101, and support steel members 104 are provided between the support bodies 103.

[0035] In this embodiment, the steel frame 102 is specifically an I-beam, and a plurality of I-beams are arranged at equal distances, buried in the ground-connected wall 101 , and fixed to the steel cage in the ground-connected wall 101 by welding.

[0036] In this embodiment, the support body 103 includes a support bracket 103a arranged on the steel frame 102 and a diagonal support plate 103b arranged below the support bracket 103a. Several support bodies 103 are equidistantly arranged along the length direction of the steel frame 102. Anti-falling facilities are installed on the support bracket 103a, and the support bracket 103a is filled with foam board. The transverse steel bars in the steel cage of the ground-connected wall 101 at the support body 103 are reasonably thickened and densely arranged according to the design to meet the support requirements of the subsequent supporting steel parts 104.

[0037] Furthermore, a concrete support is provided at the upper end of the ground-connected wall 101, which is installed above the groundwater level and is the first support to withstand greater pressure and ensure the stability and safety of the foundation pit. The support steel member 104 is installed below the groundwater level and is installed on the support bracket 103a on the steel frame 102.

[0038] Furthermore, it also includes a movable construction component 200, which includes a movable track 201 arranged above the ground-connected wall 101, and the movable track 201 is arranged at the upper end of the steel frame 102. A mobile track car 202 is slidably connected to the mobile track 201, and a working track car 203 is also slidably connected to the mobile track car 202 for excavation, lifting, bottom sealing and other works. Traveling wheels are arranged at the lower end of the mobile track car 202 for traveling on the mobile track 201, and a small track is also arranged at the upper end of the mobile track car 202. The small track is for the movement of the working track car 203. In this embodiment, the mobile track 201 and the small track are arranged perpendicular to each other.

[0039] Furthermore, it also includes a working component 300. In this embodiment, the working component 300 includes a leveling component 301 and a stirring and suction component 302 arranged on the working rail vehicle 203. The stirring and suction component 302 is used for excavating the foundation pit, discharging mud and bottom grouting. The leveling component 301 performs leveling after the stirring and suction component 302 works.

[0040] Furthermore, the stirring and suction component 302 is installed on a movable trolley and is used for excavating foundation pits, discharging mud and grouting the bottom. The stirring and suction component 302 includes a pipe body 302a arranged on the working track vehicle 203, and a water inlet pipe 302b arranged in the pipe body 302a. The water inlet pipe 302b is used to spray high-pressure water jets during excavation. A water outlet pipe 302c and a grouting pipe 302d are arranged in the pipe body 302a. The water outlet pipe 302c is used to extract mud during excavation; the grouting pipe 302d is used for grouting when the bottom is sealed, and the water inlet pipe 302b is connected to the pipe body 302a. There is one water outlet pipe 302c for each, and there are two grouting pipes 302d. A stirring and suction head 303 is provided at the lower end of the pipe body 302a. The stirring and suction head 303 is used to excavate soil in the foundation pit during excavation. The stirring and suction head 303 includes a limit plate 303a detachably connected to the pipe body 302a, a rotating cutter head 303b arranged at the lower end of the limit plate 303a, and a driving member 303c arranged at the lower end of the pipe body 302a for driving the rotating cutter head 303b to rotate. The width of the limit plate 303a is greater than that of the rotating cutter head 303b to prevent damage to the ground wall.

[0041] In this embodiment, the driving member 303c is a motor, which drives the rotation of the rotating cutter head 303b. The rotating cutter head 303b is truncated cone-shaped, and a cutting knife is provided on the outside of the rotating cutter head 303b to facilitate digging downwards.

[0042] Furthermore, a curved duct 400 is provided between the ground-connected walls 101, and a grouting leak 401 is provided on the curved duct 400. The grouting leak 401 is evenly arranged along the curved duct 400, and the distance between the edge grouting leak 401 and the edge of the pit is not greater than the grouting diffusion radius. The distance between every two adjacent grouting leaks 401 and the adjacent straight pipe part of the curved duct 400 is not greater than twice the grouting diffusion radius. Pipe connecting ports 402 are provided at both ends of the curved duct 400, and the pipe connecting ports 402 are connected to the grouting pipe 302d.

[0043] The curved conduit 400 is left in the pit bottom after grouting is completed, which is equivalent to reinforcement treatment to improve the strength of the concrete at the pit bottom. The curved conduit 400 is generally concave arched to fit the arched pit bottom that is large in the middle and thin on both sides. A number of connecting steel plates 403 corresponding to the support body 103 and adjacent curved conduits 400 are provided around the curved conduit 400. The connection method is welding to further improve the anti-uplift stability of the base.

[0044] The curved conduit 400 can ensure uniform grouting, and appropriately reducing the distance between the grouting leaks 401 on the curved conduit 400 can increase the grouting speed. After the grouting is completed, the curved conduit 400 remains in the concrete to reinforce it, which greatly improves the anti-uplift stability of the pit bottom, making the bottom sealing concrete present a concave arch shape that is large in the middle and thin on both sides, which conforms to the force form of the pit bottom and effectively improves the strength of the bottom sealing concrete.

[0045] Furthermore, in the present embodiment, the leveling component 301 includes a conveying pipe 301a detachably connected to the working rail vehicle 203 and a leveling head 301b arranged at the lower end of the conveying pipe 301a. The conveying pipe 301a is arranged vertically downward, and the lower end is hung down to the bottom of the pit. A GPS positioning module is provided on the leveling head 301b. The conveying pipe 301a continuously transports gravel to the leveling head 301b. The leveling head 301b can be adjusted according to the real-time elevation measured by GPS, so as to accurately lay a flat and solid pit bottom, and the leveling speed is very fast, which can effectively reduce and avoid the risk of siltation.

[0046] Furthermore, the supporting steel member 104 includes a movable end 104a, a fixed end 104b and a plurality of intermediate sections 104c fixedly connected between the movable end 104a and the fixed end 104b. The movable end 104a and the fixed end 104b are respectively arranged at both ends, and a plurality of intermediate sections 104c are arranged. Flange connections are formed between the intermediate sections 104c and 104c, between the intermediate sections 104c and the movable end 104a, and between the fixed end 104b and the intermediate sections 104c. The movable end 104a is provided with a self-locking hydraulic jack 105 and a stop block 106, which can ensure that the supporting steel member 104 is effectively stopped and has a self-locking function, and prevent the problem of prestress loss when the hydraulic jack 105 fails. A pressure sensor for measuring the axial pressure of the self-locking hydraulic jack 105 is provided in the fixed end 104b.

[0047] Furthermore, a limiting hole 106a is opened at the upper end of the anti-retraction block 106, a limiting rod 106b is arranged in the limiting hole 106a, an electric winder 106c, a steel wire 106d and a slider 106e are arranged in the anti-retraction block 106, and two sliders 106e are arranged. The electric winder 106c is arranged on the anti-retraction block 106 near the limiting hole 106a, the limiting rod 106b is inserted into the limiting hole 106a and welded, and the edge of the slider 106e away from the anti-retraction block 106 is wavy to increase friction.

[0048] Furthermore, the slider 106e is connected to the electric winder 106c through the steel wire 106d, and a first inclined surface and a second inclined surface are provided on the anti-retraction block 106. At the same time, inclined surfaces are provided on both sliders 106e to cooperate with the first inclined surface and the second inclined surface. When observed from the side wall of the anti-retraction block 106, one of the sliders 106e is located in the upper position and the other slider 106e is located in the lower position of the anti-retraction block 106. After use, the electric winder 106c rotates and pulls the steel wire 106d, thereby pulling the slider 106e to slide upwards for easy disassembly and assembly. Example 2

[0049] Reference Figure 1-8 , which is the second embodiment of the present invention, provides a method for underwater excavation of a deep foundation pit in a water-rich stratum, comprising the following steps: S1: Review the measurement reference points and reference lines provided by the owner, and measure the position of the ground-connected wall 101 to the site according to the designed ground-connected wall 101 coordinates, and mark them at the same time.

[0050] Since the support steel members 104 are installed underwater, the support body 103 needs to be pre-welded on the steel frame 102 of the ground-connected wall 101 where the support steel members 104 are located. Therefore, when laying out the lines, the positions of the support steel members 104 are measured together to facilitate the later construction. Then, mud is prepared with bentonite as the main raw material and appropriately mixed with admixtures such as soda ash, thickener, weighting agent, etc., and a mud pool is dug out for wall protection when the subsequent underground continuous wall project is trenched.

[0051] S2: The excavator excavates the guide trench and pours the concrete guide wall. When dividing the unit trench section, the support position is given priority, and the length of the unit trench section is divided into 4-6m according to the site conditions and design requirements. Then the trenching machine excavates the trench body of the underground continuous wall, and the mud is used to protect the wall while excavating. After the excavation, the continuous wall grabber is used to clean the bottom of the debris and deposited mud, and the circulating mud is used to replace and filter the mud in the slot hole; Then, the support body 103 is welded on the steel frame 102 where the supporting steel member 104 is located, and the supporting bracket 103a is filled with foam board, and the steel cage welded with the steel frame 102 is hoisted and lowered, and then the underground continuous wall concrete is poured.

[0052] S3: The excavator excavates to the designed bottom height of the first concrete support, which is above the groundwater level, and the first concrete support is constructed; after excavating to the groundwater level, water is injected into the pit to keep the water level inside and outside the foundation pit consistent, the movable construction assembly 200 is erected, and the stirring and suction component 302 is installed on the trolley, and the excavation continues. The water inlet pipe 302b sprays a high-pressure water jet to the excavation site, and the rotating cutter head 303b of the stirring and suction head 303 rotates rapidly to excavate and advance, and then the mud is pumped out through the water outlet pipe 302c. The water level changes in the pit are monitored at all times during the subsequent construction process to keep the water level inside and outside the pit consistent.

[0053] S4: After excavating to the designed position of the second supporting steel member 104, remove the foam board filled in the supporting bracket 103a and clean the supporting bracket 103a, install anti-falling facilities on the supporting bracket 103a, fix it to the ground-connected wall 101 with expansion bolts, and then slowly hoist the assembled supporting steel member 104 to the designed position. When the first concrete support is blocked to the installation of the supporting steel member 104, use an underwater frogman to tie a traction rope on the support, and use the construction platform to tow the support to the corresponding supporting bracket 103a.

[0054] By using the self-locking hydraulic jack 105 at the movable end 104a of the supporting steel member 104, prestress is applied to the supporting steel member 104 in a timely manner and in stages. After the prestress reaches the design value as measured by the pressure sensor at the fixed end 104b, the hydraulic jack 105 is locked, and an underwater frogman is used to put a stop block 106 in the gap formed in the middle of the movable end 104a, and a limit rod 106b is inserted into the limit hole 106a and welded to prevent the loss of prestress. Finally, the lifting wire rope is untied, and anti-falling measures for the supporting steel member 104 are set with a steel plate and a wire rope.

[0055] S5: The subsequent installation method of the supporting steel parts 104 is the same as S2. It should be noted that when it is difficult to install the supporting steel parts 104 underwater, the underwater installation sequence can be to install some key supporting steel parts 104 first, and the supporting steel parts 104 that have not been installed at the remaining design positions can be installed after the water is lowered to the corresponding positions.

[0056] After excavation to the bottom elevation of the foundation pit, the bottom surface of the foundation pit is trimmed into a concave arch shape, and then the stirring and suction head 303 at the lower end of the stirring and suction component 302 is removed, and the curved conduit 400 is tightly connected to the two reserved grouting pipes and lowered to the bottom of the pit, and then the underwater frogman welds the curved conduit 400 to the supporting bracket 103a on the steel frame 102 and the adjacent curved conduit 400 respectively.

[0057] Underwater concrete is poured to seal the bottom, ensuring that after the bottom is sealed, the bottom concrete is thick in the middle and thin on both sides in a concave arch shape to improve its bearing capacity. After the pouring is completed, the connection between the curved conduit 400 and the two grouting pipes is removed, and the curved conduit 400 is left at the bottom of the pit for reinforcement treatment to further strengthen the strength of the concrete at the bottom of the pit.

[0058] Remove the stirring and suction component 302, and install the leveling component 301 on the trolley after the bottom concrete reaches the strength requirement. The crushed stone is continuously transported to the leveling component 301 through the tracks, and transported to the leveling head 301b through the conveying pipe 301a. The leveling head 301b is adjusted according to the real-time elevation measured by GPS to accurately lay a flat and solid pit bottom.

[0059] S6: Slowly drain the water in the foundation pit, always observe the pressure value measured by the pressure sensor and adjust the hydraulic jack 105 in time to ensure that the thrust is balanced with the soil pressure.

[0060] When leakage occurs, water is promptly injected into the pit to above the leakage port, and then anti-seepage measures are taken with the assistance of a small boat. Water is continuously pumped to the bottom of the pit, and then the main structure is constructed. After the construction of the side wall and the bottom plate is completed and the concrete reaches the strength, the lowest support steel member 104 is removed. After the construction of the side wall and the middle plate is completed and the concrete reaches the strength, the middle support steel member 104 is removed, and the space between the side wall and the ground-connected wall 101 is backfilled with cement stone powder slag. Finally, after the construction of the side wall and the top plate is completed, the first concrete support is removed, and the removal of all supports is completed. The remaining space between the side wall and the ground-connected wall 101 is backfilled with cement stone powder slag.

[0061] In my country's engineering practice, the calculation of foundation pit uplift stability is to consider the stability of the pit bottom soil. The analysis mode of the value is based on the provisions of JGJ120-2012 "Technical Code for Construction Foundation Pit Support", combined with the underwater excavation process, when the foundation pit is excavated to the bottom of the pit, there is water in the pit, so the anti-uplift safety factor Such as the formula: In the formula, the foundation bearing capacity coefficient is , , It is the weighted average weight of the soil from the bottom of the pit wall to the surface. It is the weighted average density of the soil from the bottom of the pit wall to the bottom of the pit; is the load outside the pit; H d H is the embedding depth of the ground-connected wall; e is the excavation depth of foundation pit.

[0062] Under underwater excavation, when the curved conduit 400 is added to the bottom concrete, its anti-uplift safety factor is K wz It will increase and may easily exceed the specification requirements, and thus the provision of a curved conduit 400 can effectively increase the anti-uplift performance, thereby ensuring the overall strength of the deep foundation pit.

[0063] Importantly, it should be noted that the construction and arrangement of the present application shown in a number of different exemplary embodiments are only exemplary. Although only a few embodiments are described in detail in this disclosure, it should be readily understood by those who refer to this disclosure that many modifications are possible (e.g., the size, scale, structure, shape and proportion of various elements, and parameter values ​​(e.g., temperature, pressure, etc.), mounting arrangements, use of materials, color, changes in orientation, etc.) without substantially departing from the novel teachings and advantages of the subject matter described in the application. For example, an element shown as integrally formed may be composed of multiple parts or elements, the position of the element may be inverted or otherwise changed, and the nature or number or position of the discrete element may be altered or changed. Therefore, all such modifications are intended to be included within the scope of the present invention. The order or sequence of any process or method steps may be changed or reordered according to an alternative embodiment. In the claims, any "device plus function" clause is intended to cover the structure described herein that performs the function, and is not only structurally equivalent but also equivalent structure. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the exemplary embodiments without departing from the scope of the present invention. Therefore, the invention is not limited to a specific embodiment, but extends to numerous modifications still falling within the scope of the appended claims.

[0064] Additionally, in order to provide a concise description of exemplary embodiments, all features of an actual embodiment may not be described (ie, those features that are not relevant to the best mode presently contemplated for carrying out the invention or those features that are not relevant to implementing the invention).

[0065] It will be appreciated that in the development of any actual implementation, as in any engineering or design project, numerous implementation-specific decisions may be made. Such a development effort may be complex and time-consuming, but will be a routine task of design, fabrication, and production for those of ordinary skill having the benefit of this disclosure without undue experimentation.

[0066] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. An underwater excavation device for deep foundation pits in water-rich strata, characterized in that: include, The enclosure assembly (100) comprises a ground-connected wall (101) arranged in a stratum, a steel frame (102) arranged on the ground-connected wall (101), and a support body (103) arranged on the steel frame (102), wherein support steel members (104) are arranged between the support bodies (103); A movable construction assembly (200) comprises a movable track (201) arranged above a ground-connected wall (101), a movable track vehicle (202) arranged on the movable track (201), and a working track vehicle (203) arranged on the movable track vehicle (202); and, The working assembly (300) comprises a leveling component (301) and a stirring and suction component (302) arranged on a working rail vehicle (203); the stirring and suction component (302) is used for excavating a foundation pit, discharging mud and performing bottom grouting; and the leveling component (301) performs leveling after the stirring and suction component (302) is working.

2. The underwater excavation device for deep foundation pit in water-rich strata according to claim 1, characterized in that: The stirring and suction component (302) comprises a pipe body (302a) arranged on a working rail vehicle (203), a water inlet pipe (302b) arranged in the pipe body (302a), a water outlet pipe (302c) arranged in the pipe body (302a), and a grouting pipe (302d); a stirring and suction head (303) is arranged at the lower end of the pipe body (302a); the stirring and suction head (303) comprises a limit plate (303a) detachably connected to the pipe body (302a), a rotating cutter head (303b) arranged at the lower end of the limit plate (303a), and a driving member (303c) arranged at the lower end of the pipe body (302a) for driving the rotating cutter head (303b) to rotate; the width of the limit plate (303a) is greater than the width of the rotating cutter head (303b).

3. The underwater excavation device for deep foundation pit in water-rich strata according to claim 2, characterized in that: A curved conduit (400) is provided between the lower ends of the ground-connected wall (101), the curved conduit (400) being in a concave arch shape as a whole, a grouting leak (401) being provided on the curved conduit (400), the grouting leak (401) being evenly arranged along the curved conduit (400), the distance between the edge of the grouting leak (401) and the pit edge being no greater than the grouting diffusion radius, the distance between every two adjacent grouting leaks (401) and the adjacent straight pipe portion of the curved conduit (400) being no greater than twice the grouting diffusion radius, pipe connection ports (402) being provided at both ends of the curved conduit (400), the pipe connection ports (402) being connected to the grouting pipe (302d), and a plurality of connecting steel plates (403) corresponding to the support body (103) and adjacent curved conduits (400) being provided around the curved conduit (400).

4. The underwater excavation device for deep foundation pit in water-rich strata according to claim 1 or 3, characterized in that: The support body (103) comprises a support bracket (103a) arranged on a steel frame (102) and a diagonal support plate (103b) arranged below the support bracket (103a); a plurality of the support bodies (103) are arranged equidistantly along the length direction of the steel frame (102); the support bracket (103a) is filled with a foam board; and the transverse steel bars in the steel cage of the ground-connected wall (101) at the support body (103) are reasonably thickened and densely arranged according to the design.

5. The underwater excavation device for deep foundation pit in water-rich strata according to claim 1, characterized in that: The supporting steel member (104) comprises a movable end (104a), a fixed end (104b), and a plurality of intermediate sections (104c) fixedly connected between the movable end (104a) and the fixed end (104b); the movable end (104a) is provided with a self-locking hydraulic jack (105) and a stop block (106); the stop block (106) is stuck in a gap formed by the movable end (104a); A limiting hole (106a) is provided at the upper end of the anti-retraction block (106); a limiting rod (106b) is provided in the limiting hole (106a); an electric winding machine (106c), a steel wire (106d) and a sliding block (106e) are provided in the anti-retraction block (106); an edge of the sliding block (106e) is wavy; the sliding block (106e) is connected to the electric winding machine (106c) via the steel wire (106d); and a pressure sensor for measuring the axial pressure of the self-locking hydraulic jack (105) is provided in the fixed end (104b).

6. The underwater excavation device for deep foundation pit in water-rich strata according to claim 1, characterized in that: The leveling component (301) comprises a conveying pipe (301a) detachably connected to a working rail vehicle (203) and a leveling head (301b) arranged at the lower end of the conveying pipe (301a); a leveling driving member (301c) for controlling the operation of the leveling head (301b) is arranged in the conveying pipe (301a); and a GPS positioning module is arranged on the leveling head (301b).

7. An underwater excavation construction method for a deep foundation pit in a water-rich stratum according to any one of claims 1 to 6, characterized in that: include: The measurement reference points and reference lines of the target location are reviewed, and the location of the ground-connected wall (101) is measured to the site according to the designed coordinates of the ground-connected wall (101), and marked; Digging a guide trench and pouring a concrete guide wall, digging a trench body of the underground continuous wall by a trenching machine, welding a support body (103) on a steel frame (102) at the location of the supporting steel member (104), filling a supporting bracket (103a) with a foam board, hoisting and lowering a steel cage welded with the steel frame (102), and then pouring the underground continuous wall concrete; Excavate and construct the first concrete support. After excavating to the groundwater level, inject water into the pit to keep the water level inside and outside the foundation pit consistent. Set up a movable construction assembly (200), install a stirring and suction component (302) on a trolley, continue excavating, and pump out mud at the same time. During the subsequent construction process, monitor the water level changes in the pit at all times to keep the water level inside and outside the pit consistent. After excavating to the designed position of the second supporting steel member (104), remove the foam board filled on the supporting bracket (103a), clean the supporting bracket (103a), install anti-falling facilities on the supporting bracket (103a), fix it to the ground-connected wall (101) with expansion bolts, and then slowly hoist the assembled supporting steel member (104) to the designed position, and install the remaining supporting steel members (104) in sequence; Excavate to the bottom of the foundation pit and trim the bottom of the pit into a concave arch shape, install and lower the curved guide tube (400), continue to cast the bottom, and use the leveling component (301) to level it, and slowly drain the water in the foundation pit, always observe the pressure value measured by the pressure sensor and adjust the hydraulic jack (105) in time to ensure that the thrust is balanced with the soil pressure; The main structure is constructed. After the construction of the side wall and the bottom plate is completed and the concrete reaches the required strength, the lowest support steel member (104) is removed. After the construction of the side wall and the middle plate is completed and the concrete reaches the required strength, the middle support steel member (104) is removed. The space between the side wall and the ground-connected wall (101) is backfilled with cement stone powder slag. Finally, after the construction of the side wall and the top plate is completed, the first concrete support is removed. The removal of all supports is completed. The remaining space between the side wall and the ground-connected wall (101) is backfilled with cement stone powder slag.

8. The underwater excavation construction method for deep foundation pit in water-rich strata according to claim 7, characterized in that: The above steps also include, When the first concrete support is blocked to the support steel member (104) for installation, an underwater frogman is used to tie a traction rope on the support steel member (104), and the support is pulled to the corresponding support bracket (103a) by means of a movable construction assembly (200); a self-locking hydraulic jack (105) at the movable end (104a) of the support steel member (104) is used to timely apply prestress to the support steel member (104) in stages, and the hydraulic jack (105) is locked after the prestress reaches the design value through the pressure sensor at the fixed end (104b), and a stop block (106) is placed in the gap formed in the middle of the movable end (104a) by an underwater frogman, and a limit rod (106b) is inserted into the limit hole (106a) and welded to prevent the loss of prestress, and finally the lifting wire rope is untied, and a steel plate and a wire rope are used to set a support steel member (104) to prevent falling off.

9. The underwater excavation construction method for deep foundation pit in water-rich strata according to claim 7, characterized in that: If it is difficult to install the underwater supporting steel parts (104), the underwater installation sequence can be to first install some key supporting steel parts (104), and the remaining supporting steel parts (104) that have not been installed at the designed positions can be installed after the water level drops to the corresponding positions.

10. The underwater excavation construction method for deep foundation pit in water-rich strata according to claim 7, characterized in that: When leakage occurs while the water in the foundation pit is slowly pumped out, water is promptly injected into the pit to above the leakage point, and then a small boat is used to assist in anti-seepage measures.

Images