A water-cutting cofferdam device and concrete pier column construction method in a beaded cave dynamic water environment

Abstract

The present invention belongs to the field of foundation and basic engineering technology, specifically a water-blocking cofferdam device and a concrete pier construction method in a beaded cave dynamic water environment. The water-blocking cofferdam device includes a concrete conveying steel pipe, an annular cement grouting pipe, an annular water glass grouting pipe and a water curtain that are coaxially arranged in sequence from the inside to the outside. The water curtain is a conical cylinder structure made of flexible material. The small end of the water curtain is fixedly sleeved on the lower end of the annular water glass grouting pipe; an umbrella-shaped frame is provided in the water curtain. The umbrella-shaped frame is compressed and opened outward to open the water curtain or pulled and contracted inward to retract the water curtain. The present invention can achieve a local static water environment for the grouting material filled in the dynamic water environment before solidification through the water-blocking cofferdam device. The filled grouting material completes initial solidification in the static water environment and will not be washed away by the water flow, thereby forming a cast-in-place pile with high strength and good stability.

Description

Technical Field

[0001] The invention belongs to the technical field of foundation and basic engineering, and specifically relates to a water-cutting cofferdam device and a concrete pier column construction method in a beaded cave dynamic water environment. Background Art

[0002] Caves are natural underground spaces formed by karst formation within soluble limestone. Their development is irregular, with some developing in a string-like pattern. Their size varies greatly, and in many cases, they are filled with flowing water, easily washing away cement-based filling materials. China is a country with widespread karst, accounting for approximately one-quarter of the world's total subtropical karst area. Areas with intense karst development are unsuitable for engineering construction, yet construction often finds it difficult to avoid such sites. Filling treatment is necessary to ensure the stability of the cave roof beneath building foundations, prevent cave collapse, and ensure that the treated cave roof has sufficient bearing capacity. The commonly used treatment method at present is to drill holes and fill the caves with sand, gravel and clay, and inject cement slurry or concrete based on cave exploration. However, in a dynamic water environment, the injected cement slurry, concrete, and even the double-liquid slurry of cement and water glass are washed away by the water flow before solidification. The fine particles of loose materials such as sand, gravel and clay are more easily washed away by the water flow, resulting in large material consumption and loss, and even failure to achieve the filling and consolidation effect. After the filling is completed, it is necessary to drill holes again and construct concrete cast-in-place piles. Due to the scouring of the water flow, the cement slurry and other cementing materials of the filling body are washed away, and the coarse particles left in the filling body are loose. The drilled hole is prone to collapse, the pile filling coefficient is large, the concrete material consumption of the cast-in-place pile is high, the cost is uncontrollable, the construction process is complex, and the construction period is long. Summary of the Invention

[0003] In order to solve the problems in the above-mentioned background technology, the present invention provides a water-cutting cofferdam device and a concrete pier construction method in a dynamic water environment of a beaded cave. Through the water-cutting cofferdam device, the grouting material filled in the dynamic water environment can be provided with a static water environment in a local range before solidification. The filled grouting material completes initial setting in the static water environment and will not be washed away by the water flow; and through this construction method, an independent supporting pier or a closed cofferdam formed by a circle of overlapping supporting piers is formed at the designed position, without the need to fill the entire huge cave with filling material.

[0004] The first object of the present invention is to provide a water-blocking cofferdam device in a beaded cave dynamic water environment, comprising a concrete delivery steel pipe, an annular cement grouting pipe, an annular water glass grouting pipe and a water retaining curtain, which are coaxially arranged from the inside to the outside, wherein:

[0005] The water curtain is a conical cylindrical structure made of flexible material. The small end of the water curtain is fixedly sleeved on the lower end of the annular water glass grouting pipe, and the large end of the water curtain extends downward.

[0006] An umbrella-shaped frame is provided inside the water retaining curtain. The umbrella-shaped frame is pressed to open outwards to open the water retaining curtain or is pulled to shrink inwards to retract the water retaining curtain.

[0007] Furthermore, the umbrella-shaped frame includes a plurality of upper chord support rods circumferentially spaced along the inner conical surface of the water retaining curtain, a lower chord support rod hingedly connected to the middle of each upper chord support rod, and the lower ends of all the lower chord support rods are hingedly connected.

[0008] Furthermore, the upper chord support rod and the lower chord support rod are hinged through a first hinge point, and a horizontal support rod is also hinged on the first hinge point. A horizontal sleeve is also provided in the center of the umbrella-shaped frame and is located in the same horizontal plane as the horizontal support rod. The free end of the horizontal support rod is slidably set in the horizontal sleeve; a spring is mounted on the horizontal support rod, one end of the spring is fixed at the first hinge point, and the other end is fixed in the horizontal sleeve.

[0009] Furthermore, the upper chord support rod includes a first support rod and a second support rod, the first support rod extends toward the small end of the water retaining curtain, the second support rod extends toward the large end of the water retaining curtain, and the first support rod and the second support rod are hinged at a first hinge point.

[0010] Furthermore, the material of the water curtain is rubber or waterproof canvas.

[0011] A second object of the present invention is to provide a concrete pier construction method, which is implemented based on the above-mentioned water cut-off cofferdam device and includes the following steps:

[0012] S1. Measure and lay out, locate the center of the pile hole: move the special pipe drilling rig to the pile position, install the steel casing, hoist the drill rod and connect the drill bit.

[0013] S2. Pile hole drilling: The drilling rig power head rotates forward to drill. The debris is carried out of the hole by the spiral blade of the drill pipe. At the same time, the debris at the hole is cleaned. The steel casing sinks synchronously with the drill pipe under the guidance of the power head and the opening clamp until the top plate of the cave is drilled through.

[0014] S3. Construction of the water-blocking cofferdam: Reverse the drill bit, lift the drill rod, lower and extend the concrete delivery steel pipe, tighten and secure the annular cement grouting pipe, annular water glass grouting pipe, and water curtain to the concrete delivery steel pipe, and simultaneously lower them to the bottom of the cave. Connect the rubber hose of the concrete pump truck to the concrete delivery steel pipe, and connect the annular cement grouting pipe and annular water glass grouting pipe to their respective grouting pumps.

[0015] S4. Inject clean water into the concrete conveying steel pipe, the annular cement grouting pipe and the annular water glass grouting pipe respectively, clean the pipes under the action of water pressure, and clean the fillings in the cave.

[0016] S5. After the umbrella-shaped frame contacts the bottom of the cave, pressure is applied downward to the umbrella-shaped frame to fully open the water retaining curtain in the cave. The concrete pump is started to pump concrete into the cave through the concrete delivery steel pipe. At the same time, the cement slurry grouting pump and the water glass grouting pump are started to pump cement slurry and water glass into the cave. The concrete pumped out from the bottom of the cave flows and diffuses to the surroundings, and mixes with the cement slurry sprayed from the annular cement grouting pipe and the water glass sprayed from the annular water glass grouting pipe at the edge of the water retaining curtain. It flows outward for a certain distance and then solidifies, forming a frustum-shaped concrete pier with the outer shell solidifying first and the inner core solidifying later.

[0017] S6: Continuously pump concrete, cement slurry and water glass into the cave, and at the same time lift the concrete delivery steel pipe, annular cement grouting pipe and annular water glass grouting pipe. When the poured concrete reaches a height of 500mm to 1000mm above the cave roof, stop pumping concrete. At this time, a continuously poured frustum-shaped concrete pier is formed in the cave.

[0018] S7. Lift the concrete delivery steel pipe, annular cement slurry grouting pipe, annular water glass grouting pipe and water curtain completely to the ground and rinse them with clean water.

[0019] S8. Repeat steps S1-S7 to form multiple frustum-shaped concrete piers in the cave.

[0020] Furthermore, when there are two layers of caves, after the concrete piers in the first layer of caves have initially solidified, the drill bit is aligned with the center of the pile hole and continues to drill downward until the top plate of the second layer of caves is penetrated. Steps S1-S7 are repeated to form multiple cone-shaped concrete piers in the second layer of caves.

[0021] Furthermore, the frustum-shaped concrete pier has a double-layer structure, wherein the inner core is a concrete structure and the outer shell is a mixture structure of concrete, cement slurry and water glass.

[0022] Preferably, when constructing large-diameter cast-in-place piles with a diameter of more than 2.0 m, the multiple frustum-shaped concrete piers formed in step S8 are arranged in a ring and overlap and engage with each other to form a hollow and closed water-cutting cofferdam.

[0023] Furthermore, in step S2, the opening clamp includes two hingedly connected arc-shaped movable clamp pieces, a hard rubber clamp piece fixed on the inner side of the arc-shaped movable clamp piece, and a telescopic cylinder that drives the two arc-shaped movable clamp pieces to clamp or release the steel casing.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a water-blocking cofferdam device and concrete pier construction method for a beaded karst cave in a dynamic water environment. A water curtain is used to partially seal water. Cement slurry and water glass are mixed with concrete around the water curtain to form a rapidly solidifying concrete cone-shaped protective shell. This protects the concrete pumped from the concrete delivery steel pipe from being washed away by the water flow as it spreads to the surrounding area under pressure. Furthermore, the entire karst cave does not need to be filled with grout, which can significantly reduce the material consumption for karst cave treatment. If the diameter of a single concrete support pier is more than 20% larger than the pile diameter, a cast-in-place pile is constructed at the center of the single concrete pier. For large-diameter cast-in-place piles, a water-blocking cofferdam can be provided for the construction of large-diameter cast-in-place piles with a diameter of more than 2.0 m by constructing multiple, interlocking cone-shaped concrete piers arranged in a ring. The present invention can reduce material consumption and lower project costs. Furthermore, the construction equipment of the present invention is highly mechanized. Compared with traditional karst cave treatment methods and publicly available patented technologies, the present invention reduces construction costs by more than 30% and shortens construction time by 20% to 30%. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 paying any creative work.

[0027] Figure 1 This is a schematic diagram of the water curtain tightening structure of the water cut-off cofferdam device of the present invention.

[0028] Figure 2 This is a schematic diagram of the structure of the water curtain opening of the water-blocking cofferdam device of the present invention.

[0029] Figure 3 Schematic diagram of the working condition of the drill rod with spiral blades drilling in step S2 of the present invention;

[0030] Figure 4 Schematic diagram of the working condition of the drill bit with spiral blades penetrating the cave roof in step S2 of the present invention;

[0031] Figure 5 This is a schematic diagram of the working conditions of lifting the drill rod upward, lowering and installing the concrete delivery steel pipe, the annular cement grouting pipe and the annular water glass grouting pipe, and starting to pour concrete into the cave bottom in steps S3 and S5 of the present invention;

[0032] Figure 6 This is a schematic diagram of the working condition in which concrete has been poured from the bottom of the cave to above the cave roof in step S6 of the present invention, and the concrete delivery steel pipe, the annular cement grouting pipe, and the annular water glass grouting pipe are lifted to above the cave top to form a double-layer structure concrete pier column;

[0033] Figure 7 for Figure 6 Cross-section of multiple double-layer concrete piers formed in the cave;

[0034] Figure 8 for Figure 6 Plan view of multiple double-layer concrete piers formed in the cave;

[0035] Figure 9 This is a schematic diagram of the working condition of aligning the drill bit with the center of the hole and continuing to drill downward to penetrate the second layer of the cave roof in the present invention;

[0036] Figure 10 In the present invention, the above steps S1 to S7 are repeated to complete the pouring of the second layer of karst cave concrete piers and water cut-off cofferdams.

[0037] Figure 11 This is a schematic plan view of a frustum-shaped concrete pier column wrapped with a rapid-setting body formed in step S5 of the present invention.

[0038] Figure 12 This is a plan view of the closed water-cutting cofferdam formed by the frustum-shaped concrete piers wrapped with rapid-setting bodies that interlock with each other when constructing large-diameter cast-in-place piles with a diameter of more than 2.0m.

[0039] Figure 13 It is the drill rod with spiral blades in step S1 of the present invention.

[0040] Figure 14 Schematic diagram of the opening clamp in step S2 of the present invention.

[0041] Figure 15 Schematic diagram of the control principle of the telescopic cylinder of the opening clamp in step S2 of the present invention.

[0042] Figure 16 Schematic diagram of the steel hoop structure in step S3 of the present invention.

[0043] Among them: 1-drilling rig, 2-drill pipe, 3-steel casing, 4-reaming drill bit, 5-concrete pump truck, 6-rubber hose, 7-steel hoop, 71-pin, 72-rubber sealing ring, 73-bolt, 74-nut, 11-power head, 12-open clamp, 121-arc-shaped movable clamp, 122-hard rubber clamp, 123-pin, 124-oil cylinder, 125-piston rod, 126-hinge support, 127-clamp bolt, 128-clamp nut, 129-hydraulic oil, 22-concrete pump Delivery steel pipe, 23-annular cement grouting pipe, 231-cement grouting hole, 232-cement slurry, 24-annular water glass grouting pipe, 241-water glass grouting hole, 242-water glass, 25-water curtain, 251-rubber skin or waterproof canvas, 252-upper chord support rod, 253-horizontal sleeve, 254-horizontal support rod, 255-spring, 256-lower chord support rod, 26-concrete, 261-rapid-setting concrete shell, 30-cavity, 50-concrete pier, 100-dynamic water. DETAILED DESCRIPTION

[0044] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0045] The following is combined with Figure 1 To the attached Figure 16 The present invention is described in detail with specific embodiments.

[0046] like Figure 1-2As shown, the present invention provides a water-blocking cofferdam device in a beaded cave dynamic water environment, comprising a concrete conveying steel pipe 22, an annular cement grouting pipe 23, an annular water glass grouting pipe 24 and a water retaining curtain 25 which are coaxially arranged from the inside to the outside. The diameter of the concrete conveying steel pipe 22 is the smallest, followed by the annular cement grouting pipe 23 and the annular water glass grouting pipe 24. The annular cement grouting pipe 23 is fixedly sleeved on the outer surface of the concrete conveying steel pipe 22, and the annular water glass grouting pipe 24 is fixedly sleeved on the outer surface of the annular cement grouting pipe 23. The water retaining curtain 25 is a conical cylinder structure made of flexible material, comprising a small end and a large end. The small end of the water retaining curtain 25 is fixedly sleeved on the lower end of the annular water glass grouting pipe 24. The large end of the water retaining curtain 25 extends downward. When in use, the annular cement grouting pipe 23, the annular water glass grouting pipe 24 and the water retaining curtain 25 are driven to move upward or downward by lifting or lowering the concrete conveying steel pipe 22; an umbrella-shaped frame is provided inside the water retaining curtain 25. During construction, the concrete conveying steel pipe 22 moves downward and exerts a certain pressure on the umbrella-shaped frame. Since the bottom end of the umbrella-shaped frame contacts the rock, the water retaining curtain 25 opens outward under the action of pressure. The function of the water retaining curtain 25 is to keep the moving water 100 in the cave 30 out and form a local static water environment inside; when the grouting is completed, the concrete conveying steel pipe 22 is lifted, and the umbrella-shaped frame shrinks inward under the action of the lifting force, thereby causing the water retaining curtain 25 to also shrink inward.

[0047] Specifically, the umbrella-shaped frame includes a plurality of upper chord support rods 252 circumferentially spaced along the inner conical surface of the water curtain 25, and a lower chord support rod 256 hingedly connected to the middle portion of each upper chord support rod 252. The upper chord support rods 252 extend from the small end to the large end of the water curtain 25, and the lower ends of all the lower chord support rods 256 are hingedly connected. In this embodiment, the umbrella-shaped frame is expanded and contracted by the hinged connection, resulting in a simple structure and strong practicality.

[0048] Specifically, the upper chord support rod 252 and the lower chord support rod 256 are hinged through a first hinge point, and a horizontal support rod 254 is also hinged on the first hinge point, that is, a horizontal support rod 254 is hinged on each first hinge point, and a horizontal sleeve 253 is also provided at the center of the umbrella-shaped frame, which is located on the same horizontal plane as the horizontal support rod 254. It can be imagined that there are multiple horizontal sleeves 253, and multiple horizontal sleeves 253 are fixedly connected at the center, and multiple horizontal sleeves 253 form a circular fixed area. The horizontal sleeves 253 are arranged in a one-to-one correspondence with the horizontal support rod 254, and the free end of the horizontal support rod 254 is slidably arranged in the relatively arranged horizontal sleeve 253; the horizontal support rod 254 is also provided with a spring 255, one end of the spring 255 is fixed at the first hinge point, and the other end is fixed in the relatively arranged horizontal sleeve 253. When the water curtain 25 is in the retracted state, the horizontal support rod 254 is partially located in the horizontal sleeve 253 under the elastic force of the spring 255; under the downward pressure of the concrete conveying steel pipe 22, the umbrella-shaped frame is opened, and the horizontal support rod 254 slides outward from the horizontal sleeve 253, so that the spring 255 is in a stretched state. When the downward pressure force disappears, the water curtain 25 is lifted upward, and the umbrella-shaped frame contracts inward under the action of the lifting force and the spring force, thereby lifting the water curtain 25 to the ground.

[0049] Specifically, the upper chord support rod 252 includes a first support rod and a second support rod. The first support rod extends toward the small end of the water curtain 25, and the second support rod extends toward the large end of the water curtain 25. The first support rod and the second support rod are hinged at a first hinge point. The hinge point of the lower chord support rod 256 is defined as the second hinge point. When the water curtain 25 is in the retracted state, the second hinge point is located below the bottom end of the second support rod. When the water curtain 25 is in the extended state, the second hinge point and the bottom end of the second support rod are located at the same horizontal plane, thereby achieving a static water environment within the interior of the water curtain 25, and blocking the moving water 100 outside the water curtain 25.

[0050] Specifically, the material of the water curtain 25 is rubber or waterproof canvas 251. It is in a drooping state without internal support and can only be opened to achieve the water-blocking effect under the support of the internal umbrella-shaped frame.

[0051] The water-blocking cofferdam device of the present invention can achieve a static water environment in a local range for the grouting material filled in the dynamic water environment before solidification through the setting of the water retaining curtain. The filled grouting material completes the initial setting in the static water environment and will not be washed away by the water flow, without the need to fill the entire huge cave with filling material.

[0052] like Figure 1-16 As shown, the present invention also provides a concrete pier column construction method, which is implemented based on the above-mentioned water cutoff cofferdam device and includes the following steps:

[0053] S1. Measure and lay out the lines, and locate the center of the pile hole: move the special drilling rig 1 to the pile position, install the steel casing 3, hoist the drill rod 2 and connect the reaming drill bit 3. The drill rod 2 is a drill rod with spiral blades. The soil is automatically brought out of the ground by the rotation of the spiral blades of the drill rod 2. Figure 3 shown.

[0054] When the reaming drill bit 4 penetrates the top plate of the cave, the open clamp 12 clamps the steel casing 3, which will not cause the steel casing 3 to suddenly fall into the cave. Figure 4 As shown;

[0055] S3, water cut-off cofferdam construction: reverse the reaming drill bit 4, lift the drill rod 2, lower and lengthen the concrete delivery steel pipe 22, and at the same time tighten the annular cement grouting pipe 23, the annular water glass grouting pipe 24 and the water curtain 25 and fix them on the concrete delivery steel pipe 22 and lower them to the bottom of the cave 30, and connect the rubber tube 6 of the concrete pumping vehicle 5 to the concrete delivery steel pipe 22 with a steel hoop 7, and connect the annular cement grouting pipe 23 and the annular water glass grouting pipe 24 to their grouting pumps respectively. The lower end of the shaped cement grouting pipe 23 is provided with a cement grouting hole 231, and the annular water glass grouting pipe 24 is provided with a water glass grouting hole 241; the steel hoop 7 is formed by two semicircular steel hoops hinged by a pin 71, and the open ends of the two semicircular steel hoops are fixedly connected by bolts 73 and nuts to make the steel hoop 7 into a closed circular ring. A rubber sealing ring 72 is sleeved inside the steel hoop 7. When in use, one end of the concrete delivery steel pipe 22 is inserted into the rubber tube 6, and the steel hoop 7 is used to tightly connect them. Figure 16 shown.

[0056] S4. Inject clean water into the concrete delivery steel pipe 22, the annular cement grouting pipe 23 and the annular water glass grouting pipe 24 respectively, clean the pipes under the action of water pressure, and clean the filling material in the cave 30.

[0057] S5. After the umbrella-shaped frame contacts the bottom of the cave, it is pressed downward to make the water curtain 25 fully open in the cave, and concrete 26 is poured into the concrete pumping truck 5. The concrete pump is started to pump concrete into the cave 30 through the concrete delivery steel pipe 22. At the same time, the cement slurry grouting pump and the water glass grouting pump are started to pump cement slurry 232 and water glass 242 into the cave 30. The concrete pumped out from the bottom of the cave 30 flows and diffuses to the surrounding areas, and mixes with the cement slurry 232 sprayed from the annular cement grouting pipe 23 and the water glass 242 sprayed from the annular water glass grouting pipe 24 at the edge of the water curtain 25. It flows outward for a certain distance and then solidifies to form a rapidly solidified concrete shell 261. The frustum-shaped concrete pier 50 whose inner core solidifies later prevents the water from washing away the concrete. The grouting pressure of the cement slurry and water glass is 0.3MPa~3.0Mpa. Figure 7 、 Figure 8 、 Figure 11 、 Figure 12 As shown;

[0058] S6: Continuously pump concrete 26, cement slurry 232 and water glass 242 into the cave 30, and at the same time, lift the concrete delivery steel pipe 22, the annular cement grouting pipe 23 and the annular water glass grouting pipe 24. When the poured concrete reaches a height of 500mm to 1000mm above the cave roof, stop pumping the concrete. At this time, a continuously poured frustum-shaped concrete pier 50 is formed in the cave. Figure 6 As shown;

[0059] S7. Lift the concrete delivery steel pipe 22, the annular cement slurry grouting pipe 23, the annular water glass grouting pipe 24 and the water retaining curtain 25 completely to the ground and rinse them with clean water.

[0060] S8. Repeat steps S1-S7 to form multiple frustum-shaped concrete piers 50 in the cave.

[0061] In other embodiments, when there are two layers of upper and lower caves in the rock soil, after the concrete piers in the first layer of caves are initially solidified, the drill bit is aligned with the center of the pile hole and continues to drill downward until the top plate of the second layer of caves is penetrated, and steps S1-S7 are repeated to form multiple cone-shaped concrete piers in the second layer of caves. Figure 9 、 Figure 10 As shown, multiple independent cone-shaped concrete piers are formed in the cave to maintain the stability of the cave roof and support the basement foundation of the building;

[0062] Specifically, such as Figure 7 、 Figure 8 As shown, the frustum-shaped concrete pier has a double-layer structure, with the inner core being a concrete structure and the outer shell being a mixture structure of concrete, cement slurry and water glass.

[0063] Preferably, when constructing large diameter bored piles with a diameter of more than 2.0 m, the multiple frustum-shaped concrete piers formed in step S8 are arranged in a ring and overlapped and engaged with each other to form a hollow and closed water-blocking cofferdam, such as Figure 12 shown.

[0064] Specifically, in step S2, as Figure 14-15 As shown, the opening clamp 12 includes two hingedly connected arc-shaped movable clamp pieces 121, a hard rubber clamp piece 122 fixed to the inner side of the arc-shaped movable clamp piece 121, and a telescopic oil cylinder that drives the two arc-shaped movable clamp pieces 121 to clamp or loosen the steel casing 3. The telescopic oil cylinder is hinged to the arc-shaped movable clamp piece 121 through a hinge support 126, and the hard rubber clamp piece 122 is fixedly connected to the arc-shaped movable clamp piece 121 through a clamp bolt 127 and a clamp nut 128. The two arc-shaped movable clamp pieces 121 are hingedly connected through a pin shaft 123. The movable clamp piece 121 includes a clamping end and a force-applying end. The telescopic oil cylinder is arranged at the force-applying end. The telescopic oil cylinder includes an oil cylinder 124 and a piston rod 125. The hydraulic oil 129 is injected into the lower end cylinder body of the oil cylinder 124 to increase the pressure. At the same time, the oil return pressure is relieved from the upper end cylinder body to make the piston rod 125 extend to control the opening clamp 12 to loosen the steel casing 3 or maintain a smaller gap; the hydraulic oil is pumped into the upper end cylinder body of the oil cylinder 124 to increase the pressure. At the same time, the oil return pressure is relieved from the lower end cylinder body. The piston rod 125 contracts to make the opening clamp 12 hold the steel casing 3 tightly, which guides the drilling rig to form holes.

[0065] This embodiment utilizes a water curtain to partially seal water, and cement slurry and water glass double liquid grouting are mixed with concrete around the water curtain to form a fast-setting concrete cone-shaped protective shell. This protects the concrete pumped out of the concrete delivery steel pipe from being washed away by the water flow when it spreads to the surrounding areas under pressure. In addition, it is not necessary to fill the entire cave with grouting, which can greatly reduce the material consumption of cave treatment. For large-diameter bored piles, by constructing multiple mutually interlocking cone-shaped concrete piers arranged in a ring, a water-blocking cofferdam can be provided for the construction of large-diameter bored piles with a diameter of more than 2.0m. Compared with the cave treatment methods of traditional technologies and publicly disclosed patented technologies, this method reduces the cost by more than 30% and shortens the construction period by 20% to 30%.

[0066] The present invention is further described above with the aid of specific embodiments. However, it should be understood that the specific description herein should not be construed as limiting the essence and scope of the present invention. Various modifications made to the above embodiments by ordinary technicians in this field after reading this specification are all within the scope of protection of the present invention.

Claims

1. A water-blocking cofferdam device in a beaded cave dynamic water environment, characterized in that: It includes a concrete conveying steel pipe, an annular cement grouting pipe, an annular water glass grouting pipe and a water curtain which are coaxially arranged from the inside to the outside, wherein: The water retaining curtain is a conical cylindrical structure made of flexible material. The small end of the water retaining curtain is fixedly sleeved on the lower end of the annular water glass grouting pipe, and the large end of the water retaining curtain extends downward. An umbrella-shaped frame is provided inside the water retaining curtain, and the umbrella-shaped frame is pressed to open outwards to open the water retaining curtain or is pulled to contract inwards to retract the water retaining curtain; The umbrella-shaped frame includes a plurality of upper chord support rods circumferentially spaced apart along the inner conical surface of the water retaining curtain, and a lower chord support rod hingedly connected to the middle of each upper chord support rod, and the lower ends of all the lower chord support rods are hingedly connected; The upper chord support rod and the lower chord support rod are hingedly connected via a first hinge point, a horizontal support rod is further hingedly connected to the first hinge point, a horizontal sleeve is further provided at the center of the umbrella-shaped frame and is located in the same horizontal plane as the horizontal support rod, and a free end of the horizontal support rod is slidably arranged in the horizontal sleeve; a spring is sleeved on the horizontal support rod, one end of the spring is fixed at the first hinge point, and the other end is fixed in the horizontal sleeve; The upper chord support rod includes a first support rod and a second support rod, the first support rod extends toward the small end of the water retaining curtain, the second support rod extends toward the large end of the water retaining curtain, and the first support rod and the second support rod are hinged at the first hinge point.

2. The water-blocking cofferdam device in a beaded cave dynamic water environment according to claim 1, characterized in that: The material of the water retaining curtain is rubber or waterproof canvas.

3. A method for constructing a concrete pier column, characterized in that: The construction method is implemented based on the water cut-off cofferdam device described in claim 1 or 2, and comprises the following steps: S1. Measure and lay out, locate the center of the pile hole: move the pipe drilling rig to the pile location, install the steel casing, hoist the drill pipe and connect the drill bit; S2. Pile hole drilling: The drilling rig power head rotates forward to drill. The debris is carried out of the hole by the spiral blade of the drill pipe. At the same time, the debris at the hole is cleaned. The steel casing sinks synchronously with the drill pipe under the guidance of the power head and the opening clamp until the top plate of the cave is drilled through. S3. Construction of the water-blocking cofferdam: Reverse the drill bit, lift the drill rod, lower and extend the concrete delivery steel pipe, tighten and secure the annular cement grouting pipe, annular water glass grouting pipe, and water curtain to the concrete delivery steel pipe, and simultaneously lower them to the bottom of the cave. Connect the rubber hose of the concrete pump truck to the concrete delivery steel pipe, and connect the annular cement grouting pipe and annular water glass grouting pipe to their respective grouting pumps. S4. Injecting clean water into the concrete delivery steel pipe, the annular cement grouting pipe, and the annular water glass grouting pipe respectively, cleaning the pipes under the action of water pressure, and cleaning the filling material in the cave; S5. After the umbrella-shaped frame contacts the bottom of the cave, downward pressure is applied to the umbrella-shaped frame to fully expand the water curtain in the cave. The concrete pump is started to pump concrete into the cave through the concrete delivery steel pipe. Simultaneously, the cement slurry grouting pump and the water glass grouting pump are started to pump cement slurry and water glass into the cave. The concrete pumped out from the bottom of the cave flows and spreads around and mixes with the cement slurry and water glass sprayed from the annular cement grouting pipe at the edge of the water curtain. After flowing outward for a certain distance, it solidifies, forming a frustum-shaped concrete pier with the outer shell solidifying first and the inner core solidifying later. S6: Continuously pump concrete, cement slurry, and water glass into the cave, while simultaneously lifting the concrete delivery steel pipe, the annular cement grouting pipe, and the annular water glass grouting pipe. When the poured concrete reaches a height of 500mm-1000mm above the cave roof, stop pumping concrete. At this point, a continuously poured frustum-shaped concrete pier is formed in the cave. S7. Lift the concrete delivery steel pipe, annular cement slurry grouting pipe, annular water glass grouting pipe, and water curtain completely to the ground and rinse them with clean water; S8. Repeat steps S1-S7 to form multiple frustum-shaped concrete piers in the cave.

4. The concrete pier construction method according to claim 3, characterized in that: When there are two layers of caves, after the concrete pier in the first layer of caves has initially solidified, align the drill bit with the center of the pile hole and continue drilling downward until the top plate of the second layer of caves is penetrated. Repeat steps S1-S7 to form multiple frustum-shaped concrete piers in the second layer of caves.

5. The concrete pier construction method according to claim 3, characterized in that: The frustum-shaped concrete pier column has a double-layer structure, wherein the inner core is a concrete structure and the outer shell is a mixed structure of concrete, cement slurry and water glass.

6. The concrete pier construction method according to claim 3, characterized in that: When constructing large-diameter cast-in-place piles with a diameter of more than 2.0 m, the multiple frustum-shaped concrete piers formed in step S8 are arranged in a ring and overlap and engage with each other to form a hollow and closed water-cutting cofferdam.

7. The concrete pier construction method according to claim 3, characterized in that: In step S2, the opening clamp includes two hingedly connected arc-shaped movable clamp pieces, a hard rubber clamp piece fixed on the inner side of the arc-shaped movable clamp piece, and a telescopic cylinder driving the two arc-shaped movable clamp pieces to clamp or release the steel casing.

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