Concrete dam section foundation pit drainage and dam foundation pouring method thereof

Abstract

The application provides a concrete dam section foundation pit drainage and dam foundation pouring method applied to the dam manufacturing field, and specifically comprises the following steps: S1, setting a drainage ditch; S2, setting multiple groups of auxiliary water collecting wells and a main water collecting well; S3, setting a steel sinking cylinder in the main water collecting well, and a water pumping system is further set in the foundation pit, wherein the water pumping system comprises a water pump, a drainage pipe is arranged at the output end of the water pump, and a water purifying mechanism and a water pressing mechanism are further arranged on the drainage pipe; S4, using the water purifying mechanism and the water pressing mechanism to complete the foundation pit drainage action, the water flow impact force during the operation of the water pump is used to automatically separate impurities, the buoyancy of the counterweight block is used to drive the water pressing mechanism to displace upward and downward as a whole, the phenomenon that the water pump is empty suction is effectively prevented, the energy consumption is reduced, the water pumping life of the water pump is prolonged, the drainage efficiency of the concrete dam section foundation pit is improved, the method has market prospects, and is suitable for promotion and application.

Description

Technical Field

[0001] The present application relates to the field of dam manufacturing, and in particular to a method for draining a foundation pit of a concrete dam section and pouring a dam foundation. Background Art

[0002] The foundation pit of a concrete dam section refers to the foundation excavated during the dam construction process to facilitate the pouring of concrete and the construction of related structures. This foundation pit is not only the foundation part of the dam, but also an important preliminary preparation for the construction of other ancillary facilities. Since the foundation pit of a concrete dam section is located relatively low in the riverbed, drainage operations are required to control the groundwater level in the foundation pit and avoid the impact of excessively high water levels on the stability of the foundation pit and construction safety. At the same time, high water levels may cause foundation pit collapse or liquefaction of the surrounding soil. Accumulated water without drainage will increase the risk at the construction site and may lead to accidents such as landslides and mudslides. Keeping the foundation pit dry can reduce these safety hazards.

[0003] The existing foundation pit drainage method usually uses a pumping system for drainage. However, since the seepage water in the riverbed contains a large amount of impurities such as sediment, it is easy to clog the pumping system, resulting in a decrease in drainage efficiency. Therefore, a concrete dam section foundation pit drainage and dam foundation casting method are proposed. Summary of the Invention

[0004] The purpose of this application is to solve the technical problems of the existing foundation pit drainage method, which is easy to clog the pumping system and has low drainage efficiency. Compared with the existing technology, a method for foundation pit drainage of a concrete dam section and dam foundation casting is provided, which specifically includes the following steps:

[0005] S1. Set up drainage ditches on the sides of the foundation pit according to the design drawings, and ensure that the upper end surface of the drainage ditch is lower than the lowest plane of the foundation pit;

[0006] S2. Set up multiple groups of secondary water collection wells in the drainage ditch, and set up main water collection wells between the secondary water collection wells on the same side. The main water collection well is deeper than the secondary water collection wells, and the secondary water collection wells on the same side are all connected to the main water collection wells;

[0007] S3. A steel caisson is installed in the main water collection well, and a water pumping system is also installed in the foundation pit. The water pumping system includes a water pump, an outlet pipe is provided at the output end of the water pump, a pumping pipe is provided at the input end of the water pump, and a drain pipe is connected to the end of the pumping pipe away from the water pump. The drain pipe is coaxially arranged with the steel caisson and is also provided with a debris removal mechanism and a water pressure mechanism;

[0008] S4. The water and impurities in the steel sink are separated by the up-and-down displacement of the water pressure mechanism and the rotation of the impurity removal mechanism, and are discharged through the water pumping system, thus completing the foundation pit drainage operation;

[0009] S5. Clean the foundation pit, remove dust, debris and plant roots on the surface, and ensure that the foundation pit surface is clean;

[0010] S6. Maintain the pumping system of the main water collection well in operation to maintain the low water level in the foundation pit. Pour concrete into the auxiliary water collection well. After the concrete in the auxiliary water collection well is completely solidified, it forms the bottom support.

[0011] S7. Build the dam foundation formwork on the bottom support formed by the auxiliary water collection well;

[0012] S8. Carry out layer-by-layer pouring in the constructed formwork, with each layer pouring thickness not exceeding 50cm, until the dam foundation is completely poured.

[0013] Furthermore, the debris removal mechanism includes an inner tube and an outer tube, the top of the drain pipe is provided with a debris removal pipe, the top of the debris removal pipe extends through the outer wall of the drain pipe, the inner tube is rotatably connected to the bottom end of the debris removal pipe, the top outer wall of the inner tube is provided with a driving blade, and the inner wall of the inner tube is provided with an inner spiral blade;

[0014] The outer tube is rotatably sleeved on the outside of the drain pipe, a separation bag is fixed to the bottom end of the outer tube, the bottom of the outer tube is fixedly connected to the bottom end of the inner tube, a separation plate is provided in the separation bag, the separation plate is fixed to the bottom end of the drain pipe, a water pumping hole is provided at the bottom end of the drain pipe, a water inlet is provided at the bottom end of the separation bag, an impurity feed port is provided at the bottom end of the inner tube, and a separation strip is fixed to the bottom of the separation plate.

[0015] Furthermore, the separation bag and the separation plate are both bowl-shaped structures with the opening facing downward, the separation strips are arranged in a vortex shape, and the separation strips have an inclination away from the inner tube in cross section. The bottom end of the separation strips conflicts with the bottom inner wall of the separation bag to form unidirectional conductivity.

[0016] Furthermore, a stacking plate is fixed to the bottom of the inner tube, a pusher blade is provided on the top of the stacking plate, and the stacking plate is in a bowl-shaped structure with an opening facing upward.

[0017] Furthermore, the water pressure mechanism includes a counterweight block, a sealing ring matching the steel sinker is fixed to the outer circumference of the counterweight block, and the counterweight block is slidably connected to the outer wall of the outer tube in the vertical direction;

[0018] The top of the counterweight block is provided with a conical top, which is in the shape of a conical convexity. The conical top of the counterweight block is provided with a plurality of water collection channels evenly distributed at equal angles. A one-way valve is fixed to the inner wall of the counterweight block at the bottom end of the water collection channel. The one-way valve has an elastic force away from the water collection channel. The outer wall of the bottom end of the outer tube is provided with an inner groove that cooperates with the one-way valve.

[0019] A floating block is fixed on the bottom of the counterweight block.

[0020] Furthermore, the top of the counterweight block is also rotatably connected to a one-way rotating seat, the top of the counterweight block is provided with a ratchet gear, the bottom of the one-way rotating seat is provided with a pawl that cooperates with the ratchet gear, the outer wall of the outer tube is also provided with a bidirectional spiral groove, and the inner wall of the one-way rotating seat is rotatably connected to a ball that cooperates with the bidirectional spiral groove.

[0021] Furthermore, two groups of symmetrically arranged limit sliding blocks are provided on the sides of the floating block, and the inner wall of the steel sinker is provided with a sliding groove matching the limit sliding blocks.

[0022] Furthermore, an energy storage spring is fixed between the counterweight block and the drain pipe, and the energy storage spring has an elastic force to drive the counterweight block to move downward.

[0023] Furthermore, a sedimentation tank is provided on the top of the main water collection well, and a water combing port is provided on the top of the steel sedimentation cylinder. The water combing port is serrated, and the highest point of the top of the water combing port is lower than the upper port of the drainage ditch, and the highest point of the top of the water combing port is higher than the bottom of the sedimentation tank.

[0024] Compared with the existing technology, the advantages of this application are:

[0025] This application uses the mutual cooperation between the water pressure mechanism with counterweight blocks and floating blocks and the impurity removal mechanism with inner tubes, outer tubes and stacking plates to automatically separate impurities by utilizing the water flow impact when the water pump is running. On the other hand, the buoyancy of the counterweight blocks is used to drive the water pressure mechanism to move up and down as a whole, pushing the accumulated water at the bottom of the steel submerged cylinder to the pump water pipe, effectively preventing the water pump from sucking air, reducing energy consumption, increasing the pumping life of the water pump, and improving the drainage efficiency of the foundation pit of the concrete dam section. It has market prospects and is suitable for promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a schematic diagram of the structure of the foundation pit proposed in this application;

[0027] Figure 2 This is a schematic diagram of the top structure of the foundation pit proposed in this application;

[0028] Figure 3 This is a schematic diagram of the structure of the drainage ditch and pumping system proposed in this application;

[0029] Figure 4 A schematic diagram of the internal structure of the steel submerged cylinder proposed in this application;

[0030] Figure 5 Schematic diagram of the cross-sectional structure of the impurity removal mechanism proposed in this application;

[0031] Figure 6 for Figure 5A schematic diagram of the enlarged structure of the middle part A;

[0032] Figure 7 for Figure 5 A schematic diagram of the enlarged structure of the middle part B;

[0033] Figure 8 This is a schematic diagram of the structure of the impurity removal mechanism proposed in this application;

[0034] Figure 9 Schematic diagram of the cross-sectional structure of the separation package proposed in this application;

[0035] Figure 10 for Figure 5 Schematic diagram of the enlarged structure of the middle C part;

[0036] Figure 11 This is a schematic structural diagram of the water pressure mechanism proposed in this application;

[0037] Figure 12 This is a schematic diagram of the explosion structure of the water pressure mechanism proposed in this application;

[0038] Figure 13 This is a schematic cross-sectional structural diagram of the water pressure mechanism proposed in this application.

[0039] Description of the numbers in the figure:

[0040] Foundation pit 1, drainage ditch 2, main water collection well 21, sedimentation tank 211, auxiliary water collection well 22, water pumping system 3, outlet pipe 31, water pumping pipe 32, water pump 33, steel sinker 4, combing port 41, chute 42, drainage pipe 5, water pumping hole 51, separation plate 52, separation rubber strip 521, impurity removal mechanism 6, driving blade 601, inner tube 61, inner spiral blade 611, impurity feed port 612, outer tube 62, bidirectional spiral groove 621, inner groove 622, stacking plate 63, pushing blade 631, separation bag 64, water inlet 641, water pressurizing mechanism 7, counterweight block 71, conical top 711, water collection channel 712, sealing ring 713, ratchet gear 714, floating block 72, limit slider 721, one-way rotating seat 73, ball 731, one-way valve 74, impurity discharge pipe 8, energy storage spring 9. DETAILED DESCRIPTION

[0041] The embodiments will be combined with the drawings in the specification to provide a clear and complete description of the technical solution of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making any creative work shall fall within the scope of protection of the present application.

[0042] Example 1:

[0043] The present invention provides a method for draining the foundation pit of a concrete dam section and pouring the dam foundation. Figure 1-13, specifically including the following steps:

[0044] S1. Set up drainage ditch 2 on the side of foundation pit 1 according to the design drawings, and ensure that the upper end surface of drainage ditch 2 is lower than the lowest plane of foundation pit 1;

[0045] S2. Multiple groups of secondary water collection wells 22 are set in the drainage ditch 2. A main water collection well 21 is set between the secondary water collection wells 22 on the same side. The depth of the main water collection well 21 is greater than that of the secondary water collection well 22. The secondary water collection wells 22 on the same side are all connected to the main water collection well 21.

[0046] S3. A steel caisson 4 is provided in the main water collection well 21. A water pumping system 3 is also provided in the foundation pit 1. The water pumping system 3 includes a water pump 33. An outlet pipe 31 is provided at the output end of the water pump 33. A pumping pipe 32 is provided at the input end of the water pump 33. A drain pipe 5 is connected to the end of the pumping pipe 32 away from the water pump 33. The drain pipe 5 is coaxially arranged with the steel caisson 4. A debris removal mechanism 6 and a water pressure mechanism 7 are also provided on the drain pipe 5.

[0047] S4, using the up and down displacement of the water pressure mechanism 7 and the rotation of the impurity removal mechanism 6 to separate the accumulated water and impurities in the steel sink 4 and discharge them through the pumping system 3, completing the foundation pit drainage action;

[0048] S5. Clean the foundation pit 1, remove dust, debris and plant roots on the surface, and ensure that the surface of the foundation pit 1 is clean;

[0049] S6: The pumping system 3 of the main water collection well 21 is kept in operation to maintain the low water level in the foundation pit 1. Concrete is poured into the auxiliary water collection well 22. After the concrete in the auxiliary water collection well 22 is completely solidified, the bottom support is formed.

[0050] S7. Build a dam foundation template on the bottom support formed by the auxiliary water collection well 22;

[0051] S8. Carry out layer-by-layer pouring in the constructed formwork, with each layer pouring thickness not exceeding 50cm, until the dam foundation is completely poured.

[0052] It should be noted that, in this embodiment, the water used for concrete mixing is stored water pumped and filtered by the water pumping system 3, and the auxiliary water collection well 22 is used as friction piles for dam foundation casting, which can effectively prevent the dam foundation casting from sinking and improve the structural stability of the dam foundation casting.

[0053] For details, please refer to Figure 3-7 The impurity removal mechanism 6 includes an inner tube 61 and an outer tube 62. The top of the drain pipe 5 is provided with a debris removal pipe 8. The top of the debris removal pipe 8 extends through the outer wall of the drain pipe 5. The inner tube 61 is rotatably connected to the bottom end of the debris removal pipe 8. The top outer wall of the inner tube 61 is provided with a driving blade 601, and the inner wall of the inner tube 61 is provided with an inner spiral blade 611.

[0054] The outer tube 62 is rotatably sleeved on the outside of the drain pipe 5, and a separation bag 64 is fixed to the bottom end of the outer tube 62. The bottom of the outer tube 62 is fixedly connected to the bottom end of the inner tube 61. A separation plate 52 is provided in the separation bag 64, and the separation plate 52 is fixed to the bottom end of the drain pipe 5. The bottom end of the drain pipe 5 is provided with a water pumping hole 51, the bottom end of the separation bag 64 is provided with a water inlet 641, the bottom end of the inner tube 61 is provided with an impurity feed port 612, and a separation strip 521 is fixed to the bottom of the separation plate 52.

[0055] See also Figure 7 It should be noted that, in this embodiment, the separation bag 64 and the separation plate 52 are both bowl-shaped structures with the opening facing downward, and the separation strips 521 are arranged in a vortex line shape. Specifically, the separation strips 521 are soft and wear-resistant rubber structures. The separation strips 521 have an inclination away from the inner tube 61 in the cross section, so that the separation strips 521 have a slope that cuts off impurities. The bottom end of the separation strips 521 conflicts with the bottom inner wall of the separation bag 64 to form a unidirectional conductivity. When the water pumping system 3 generates adsorption force, the water flow and impurities in the steel sinking cylinder 4 enter the gap between the separation plate 52 and the bottom of the separation bag 64 in advance through the water inlet 641, where the water flow will pass through The water moves upward through the water pump hole 51 and enters the gap between the drainage pipe 5 and the inner pipe 61, and is discharged through the water pump pipe 32 and the outlet pipe 31. When the water moves upward rapidly under the pump suction of the water pumping system 3, the driving blade 601 on the inner pipe 61 drives the inner pipe 61 and the outer pipe 62 to rotate as a whole. In this state, the separation plate 52 rotates with the inner pipe 61, and utilizes the vortex-shaped arrangement of the separation strip 521 to push the impurities blocked by the separation strip 521 back to the water inlet 641, thereby effectively preventing impurities such as mud, silt, etc. from causing structural damage to the water pumping system 3 during the foundation pit drainage process, thereby improving the pumping efficiency of the water pumping system 3.

[0056] For further information, see Figure 7 A stacking plate 63 is also fixed to the bottom of the inner tube 61, and a pushing blade 631 is provided on the top of the stacking plate 63. The stacking plate 63 is in a bowl-shaped structure with an opening facing upward. When the inner tube 61 rotates with the water flow in the drain pipe 5, the stacking plate 63 is driven to rotate synchronously, and the impurities falling back from the water inlet 641 are pushed to the impurity feed port 612 by the pushing of the pushing blade 631. At the same time, since the inner tube 61 is in a rotating state, the impurities accumulated at the impurity feed port 612 can be gradually pushed upward by the inner spiral blade 611, and pushed and discharged through the inner tube 61 and the impurity discharge pipe 8, which can effectively avoid the phenomenon of impurity accumulation and blockage caused by the bidirectional spiral groove 621.

[0057] To further reduce the operating power consumption of the pumping system 3, please refer to Figure 10-13 The water pressure mechanism 7 includes a counterweight block 71. A sealing ring 713 matching the steel sinker 4 is fixed to the outer circumference of the counterweight block 71. The counterweight block 71 is slidably connected to the outer wall of the outer tube 62 in the vertical direction.

[0058] The top of the counterweight 71 is provided with a conical top 711, which is a conical convex shape. The conical top 711 can further precipitate the accumulated water flowing into the steel sink 4 and collect impurities on the side of the conical top 711 by gravity.

[0059] The conical top 711 of the counterweight block 71 is provided with several water collection channels 712 evenly distributed at equal angles. The inner wall of the counterweight block 71 is fixed with a one-way valve 74 at the bottom end of the water collection channel 712. The one-way valve 74 has an elastic force away from the water collection channel 712. The outer wall of the bottom end of the outer tube 62 is provided with an inner groove 622 that cooperates with the one-way valve 74. A floating block 72 is fixed to the bottom of the counterweight block 71.

[0060] When there is no water in the steel caisson 4, the water pressure mechanism 7 uses the gravity of the counterweight block 71 to move down to the bottom of the steel caisson 4. At this time, the one-way valve 74 moves to the inner groove 622 of the outer tube 62. The one-way valve 74 is not squeezed by the outer wall of the outer tube 62 and uses its own elastic force to move away from the water collection channel 712, thereby making the water collection channel 712 open. When seepage water or rainwater is collected in the drainage ditch 2 and flows into the main water collection well 21 and the auxiliary water collection well 22, the accumulated water flows to the bottom of the steel caisson 4 through the water collection channel 712. As the water level rises, the float 72 generates buoyancy And push the counterweight 71 upward. When the upward movement of the water pressure mechanism 7 is greater than the height of the inner groove 622, the one-way valve 74 is squeezed by the outer wall of the outer tube 62 and thus overcomes its own elastic force to fit the lower end of the water collection channel 712, thereby blocking the water collection channel 712. At this time, the accumulated water collected in the drainage ditch 2 accumulates on the top of the water pressure mechanism 7. When the gravity of the accumulated water on the top of the water pressure mechanism 7 and the gravity of the counterweight 71 itself are greater than the buoyancy of the floating block 72, the water pressure mechanism 7 moves downward as a whole, thereby draining the accumulated water stored in the steel sinker 4 at the bottom of the water pressure mechanism 7 into the drain pipe 5. Because the separating rubber strip 521 is tilted and conflicts with the bottom inner wall of the separating bag 64 to form a one-way conductivity, the accumulated water in the drain pipe 5 is not easy to flow back. When the water pressure mechanism 7 moves down to the inner groove 622, the elastic force of the one-way valve 74 is released, and the one-way valve 74 moves away from the water collecting channel 712 so that the water collecting channel 712 is opened again, realizing the cyclic up and down displacement action of the water pressure mechanism 7, thereby gradually raising the water level in the drain pipe 5. In order to facilitate the water pump 33 to sense the water level of the pump pipe 32 and automatically start, a water level sensor is also provided on the top of the pump pipe 32. When the water level in the drainage pipe 5 gradually moves up to the pump pipe 32 and is sensed by the water level sensor, it indicates that the water accumulation in the drainage ditch 2 is serious, and the water pump 33 starts automatically. Since there is already accumulated water in the pump pipe 32 and the drainage pipe 5, when the water pump 33 starts, there will be no empty suction state, which can effectively avoid the damage to the pump body caused by empty suction of the water pump 33. At the same time, because the water pressure mechanism 7 uses gravity to automatically press the accumulated water at the bottom of the steel submerged cylinder 4 into the drainage pipe 5, it works on the lifting of the accumulated water, thereby reducing the operating energy consumption of the water pump 33 and achieving the purpose of energy-saving drainage.

[0061] For further information, see Figure 12 The top of the counterweight block 71 is also rotatably connected to a one-way rotating seat 73, the top of the counterweight block 71 is provided with a ratchet gear 714, the bottom of the one-way rotating seat 73 is provided with a pawl that cooperates with the ratchet gear 714, the outer wall of the outer tube 62 is also provided with a bidirectional spiral groove 621, the inner wall of the one-way rotating seat 73 is rotatably connected to a ball 731 that cooperates with the bidirectional spiral groove 621, and the side of the floating block 72 is also provided with two groups of symmetrically arranged limit sliders 721, and the inner wall of the steel sinker 4 is provided with a slide groove 42 that matches the limit slider 721.

[0062] When the water pressure mechanism 7 as a whole is moved upward by the buoyancy of the accumulated water at the bottom of the steel cistern 4, the one-way rotating seat 73 is driven to move upward synchronously. Due to the one-way non-return function of the pawl and the ratchet gear 714, the one-way rotating seat 73 cannot rotate relative to the counterweight block 71 when moving upward. At the same time, due to the restriction of the limit slider 721 and the slide groove 42, the water pressure mechanism 7 as a whole cannot rotate relative to the steel cistern 4. Then, in the process of using the buoyancy of the floating block 72 to drive the water pressure mechanism 7 to move upward, the outer tube 62 with the bidirectional spiral groove 621 driven by the ball 731 is rotated, and the buoyancy generated by the upward movement of the floating block 72 is used to drive the accumulation plate 63 to rotate, thereby collecting and gathering impurities.

[0063] When the water pressure mechanism 7 moves downward, the one-way rotating seat 73 can rotate freely relative to the counterweight block 71 during the downward movement. The one-way rotating seat 73 no longer drives the outer tube 62 of the bidirectional spiral groove 621 to rotate. On the one hand, the power loss of the water pressure mechanism 7 moving downward is reduced. On the other hand, since the water pump 33 uses the driving blades 601 to drive the inner tube 61 and the outer tube 62 to rotate when working, the water pump 33 avoids the need to generate additional power to drive the water pressure mechanism 7 downward when working. When moving upward, the water pressure mechanism 7 uses buoyancy to automatically move upward, and will not consume the power of the water pump 33.

[0064] For further information, see Figure 13 In order to increase the power of the water pressure mechanism 7 when it moves downward, an energy storage spring 9 is fixed between the counterweight block 71 and the drain pipe 5. The energy storage spring 9 has the elastic force to drive the counterweight block 71 to move downward. When the water pressure mechanism 7 moves upward, the energy storage spring 9 is squeezed to store elastic potential energy, so that when the water pressure mechanism 7 moves downward, it is pushed by the gravity of the top of the water pressure mechanism 7, the gravity of the counterweight block 71 and the elastic potential energy stored in the energy storage spring 9, further increasing the power of the water pressure mechanism 7 to move downward and discharge the accumulated water at the bottom of the water pressure mechanism 7 into the drain pipe 5.

[0065] See also Figure 4-5A sedimentation tank 211 is also provided on the top of the main water collection well 21, so that the accumulated water collected by the drainage ditch 2 can be precipitated through the sedimentation tank 211, and some large-mass impurities can be precipitated in the sedimentation tank 211. A combing port 41 is provided on the top of the steel sinking cylinder 4. The combing port 41 is serrated, and the highest point of the top of the combing port 41 is lower than the upper port of the drainage ditch 2, and the highest point of the top of the combing port 41 is higher than the bottom of the sedimentation tank 211. When the height of the accumulated water in the sedimentation tank 211 is higher than the combing port 41, the floating objects are cut off at the port of the combing port 41 after further screening by the combing port 41, thereby reducing the impurity conveying pressure of the accumulation plate 63.

[0066] The present application cooperates with the water pressure mechanism 7 with the counterweight block 71 and the floating block 72 and the impurity removal mechanism 6 with the inner tube 61, the outer tube 62 and the stacking plate 63 to automatically separate impurities by utilizing the water flow impact when the water pump 33 is running. On the other hand, the buoyancy of the counterweight block 71 is utilized to drive the water pressure mechanism 7 to move up and down as a whole, pushing the accumulated water at the bottom of the steel submerged cylinder 4 to the water pump pipe 32, effectively preventing the water pump 33 from experiencing the phenomenon of empty suction, thereby reducing energy consumption while increasing the water pumping life of the water pump 33 and improving the drainage efficiency of the foundation pit of the concrete dam section. The present application has market prospects and is suitable for promotion and application.

[0067] The above is only the best implementation method adopted by this application in combination with current actual needs, but the scope of protection of this application is not limited to this.

Claims

1. A method for draining a concrete dam section foundation pit and pouring a dam foundation, characterized in that: The specific steps include: S1. Set up a drainage ditch (2) on the side of the foundation pit (1) according to the design drawings, and ensure that the upper end surface of the drainage ditch (2) is lower than the lowest plane of the foundation pit (1); S2. Multiple groups of auxiliary water collection wells (22) are set in the drainage ditch (2), and main water collection wells (21) are set between the auxiliary water collection wells (22) on the same side. The depth of the main water collection well (21) is greater than that of the auxiliary water collection wells (22), and the auxiliary water collection wells (22) on the same side are all connected to the main water collection well (21); S3. A steel caisson (4) is provided in the main water collection well (21), and a water pumping system (3) is also provided in the foundation pit (1). The water pumping system (3) includes a water pump (33), an outlet pipe (31) is provided at the output end of the water pump (33), and a water pumping pipe (32) is provided at the input end of the water pump (33). An end of the water pumping pipe (32) away from the water pump (33) is connected to a drainage pipe (5), and the drainage pipe (5) is coaxially provided with the steel caisson (4). The drainage pipe (5) is also provided with a debris removal mechanism (6) and a water pressure mechanism (7); S4, using the up and down displacement of the water pressure mechanism (7) and the rotation of the impurity removal mechanism (6) to separate the accumulated water and impurities in the steel sinking cylinder (4) and discharge them through the water pumping system (3), thus completing the foundation pit drainage action; S5. Clean the foundation pit (1), remove dust, debris and plant roots on the surface, and ensure that the surface of the foundation pit (1) is clean; S6, the pumping system (3) of the main water collection well (21) is kept in operation, the low water level in the foundation pit (1) is maintained, and concrete is poured into the auxiliary water collection well (22), and after the concrete in the auxiliary water collection well (22) is completely solidified, a bottom support is formed; S7, constructing a dam foundation template on the bottom support formed by the auxiliary water collection well (22); S8. Pour the dam foundation in layers within the constructed formwork, with each layer no thicker than 50 cm, until the dam foundation is completely poured. The impurity removal mechanism (6) comprises an inner tube (61) and an outer tube (62); a debris removal tube (8) is provided at the top of the drainage tube (5); the top of the debris removal tube (8) extends through the outer wall of the drainage tube (5); the inner tube (61) is rotatably connected to the bottom end of the debris removal tube (8); a driving blade (601) is provided on the outer wall of the top of the inner tube (61); and an inner spiral blade (611) is provided on the inner wall of the inner tube (61); The outer tube (62) is rotatably sleeved on the outside of the drain pipe (5), a separation bag (64) is fixed to the bottom end of the outer tube (62), the bottom of the outer tube (62) is fixedly connected to the bottom end of the inner tube (61), a separation plate (52) is provided in the separation bag (64), the separation plate (52) is fixed to the bottom end of the drain pipe (5), a water pump hole (51) is provided at the bottom end of the drain pipe (5), a water inlet (641) is provided at the bottom end of the separation bag (64), an impurity feed port (612) is provided at the bottom end of the inner tube (61), and a separation strip (521) is fixed to the bottom of the separation plate (52); The separation bag (64) and the separation plate (52) are both in a bowl-shaped structure with the opening facing downward, the separation strip (521) is arranged in a vortex shape, and the separation strip (521) has an inclination away from the inner tube (61) in the cross section, and the bottom end of the separation strip (521) contacts the bottom inner wall of the separation bag (64) to form a unidirectional conductivity; A stacking plate (63) is also fixed to the bottom of the inner tube (61), and a pusher blade (631) is provided on the top of the stacking plate (63). The stacking plate (63) is in a bowl-shaped structure with an opening facing upwards. The water pressure mechanism (7) includes a counterweight (71), a sealing ring (713) matching the steel sinker (4) is fixed to the outer circumference of the counterweight (71), and the counterweight (71) is slidably connected to the outer wall of the outer tube (62) in the vertical direction; The top of the counterweight (71) is provided with a conical top (711), and the conical top (711) is in the shape of a conical protrusion. The conical top (711) of the counterweight (71) is provided with a plurality of water collection channels (712) evenly spaced at equal angles. A one-way valve (74) is fixed to the inner wall of the counterweight (71) at the bottom end of the water collection channel (712). The one-way valve (74) has an elastic force away from the water collection channel (712). The outer wall of the bottom end of the outer tube (62) is provided with an inner groove (622) that matches the one-way valve (74). A floating block (72) is fixed to the bottom of the counterweight block (71).

2. A method for draining a concrete dam section foundation pit and pouring a dam foundation according to claim 1, characterized in that: The top of the counterweight (71) is also rotatably connected to a one-way rotating seat (73), the top of the counterweight (71) is provided with a ratchet gear (714), the bottom of the one-way rotating seat (73) is provided with a ratchet pawl that matches the ratchet gear (714), the outer wall of the outer tube (62) is also provided with a bidirectional spiral groove (621), and the inner wall of the one-way rotating seat (73) is rotatably connected to a ball (731) that matches the bidirectional spiral groove (621).

3. A method for draining a concrete dam section foundation pit and pouring a dam foundation according to claim 2, characterized in that: Two sets of symmetrically arranged limiting sliding blocks (721) are further provided on the sides of the floating block (72), and the inner wall of the steel sinking cylinder (4) is provided with a sliding groove (42) matching the limiting sliding blocks (721).

4. A method for draining a concrete dam section foundation pit and pouring a dam foundation according to claim 3, characterized in that: An energy storage spring (9) is also fixed between the counterweight (71) and the drain pipe (5), and the energy storage spring (9) has an elastic force that drives the counterweight (71) to move downward.

5. A method for draining a concrete dam section foundation pit and pouring a dam foundation according to claim 4, characterized in that: A sedimentation trough (211) is further provided at the top of the main water collection well (21), and a water combing port (41) is provided at the top of the steel sink (4). The water combing port (41) is sawtooth-shaped, and the highest point of the top of the water combing port (41) is lower than the upper port of the drainage ditch (2), and the highest point of the top of the water combing port (41) is higher than the bottom of the sedimentation trough (211).

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