Inverted well and method of construction thereof

Abstract

The application discloses a hanging well and a construction method thereof. The hanging well comprises an outer wall, a top ring beam and a plurality of inner wall segments. Each inner wall segment comprises an assembled layer and a post-poured layer. The assembled layer is formed by a plurality of prefabricated blocks. Each prefabricated block comprises a main reinforcement and a stirrup. Each inner side main reinforcement is connected with a second connecting reinforcement. A top surface of each prefabricated block is provided with a supplementary concrete groove. The second connecting reinforcement of each prefabricated block is inserted into a supplementary concrete hole of a previous layer and is anchored to a steel reinforcement in the hole through post-poured concrete. Free ends of the connecting reinforcements of each prefabricated block are in abutment with outer half circles of the stirrups of adjacent prefabricated blocks. The outer side main reinforcements, the connecting reinforcements and the outer half circles of the stirrups are anchored in post-poured concrete. The construction method comprises the following steps: layer-by-layer excavation, block-by-block assembly and layer-by-layer grouting and filling, so as to form vertical and horizontal overall strength, integrate the assembled layer into a whole and connect the assembled layer with the outer wall. The hanging well and the construction method thereof can shorten construction period, simplify construction procedures and save labor cost.

Description

Technical Field

[0001] This invention relates to the field of urban water supply and drainage pipe renovation and expansion construction technology, specifically to an inverted well for pipe jacking construction of water supply and drainage pipes and a construction method for the inverted well. Background Technology

[0002] With rapid urbanization, cities have expanded rapidly, and populations have increased dramatically, rendering existing water supply and drainage pipelines inadequate for current needs. Simultaneously, climate change and increased extreme weather events have led to urban flooding during the rainy season. Therefore, in recent years, municipal departments have undertaken large-scale renovations and expansions of urban water supply and drainage pipelines to address these issues. The primary method is the construction of pipe jacking shafts, which are used for pipe jacking construction to renovate and expand existing pipelines. Pipe jacking shafts mainly take several forms, including caissons, open-cut supports, and inverted shafts. Caisson construction causes significant environmental disturbance, while open-cut supports require temporary internal supports and a comprehensive support system, resulting in numerous procedures and high costs. Therefore, inverted shafts, due to their simpler construction, lower site requirements, and less impact on the surrounding environment, have gained wider adoption and application.

[0003] The construction process of existing inverted well technology is as follows:

[0004] First, drive a continuous ring of jet grouting piles along the well outline and insert longitudinal steel sections at intervals to form the outer wall of the well;

[0005] A capping ring beam with an L-shaped cross-section is constructed at the upper end of the outer wall of the well, that is, the steel cage for binding the ring beam is erected, the side formwork is erected, and the concrete of the ring beam is poured. The steel cage of the ring beam includes a vertical first connecting bar, most of which is anchored in the concrete of the ring beam while the bottom section is inserted into the soil below.

[0006] The first well inner wall segment is constructed below the capping ring beam, that is, the soil is excavated to the height of the segment, exposing the bottom section of the first connecting bar. Then, the steel cage of the well inner wall segment is tied, the formwork is erected and concrete is poured. The steel cage of the segment includes a vertical second connecting bar. The top of the second connecting bar is tied to the bottom of the first connecting bar. Most of the second connecting bar is anchored in the concrete of the segment, while the bottom section is inserted into the soil below.

[0007] The next well wall segment is constructed using the same method, that is, the soil is excavated to the height of the next segment, exposing the bottom end of the second connecting bar of the previous well wall segment. Then, the steel cage of the current well wall segment is tied, the formwork is erected and concrete is poured. When tying the steel cage, the upper end of the second connecting bar of the current segment is tied to the bottom end of the second connecting bar of the previous segment, and the bottom end of the second connecting bar of the current segment is inserted into the soil below, so that most of the second connecting bar of the current segment is anchored in the concrete of the current segment.

[0008] Excavate and construct the next layer of the well wall segment in the same manner until the bottom of the well is reached, then tie the bottom slab reinforcement cage and pour the bottom slab concrete.

[0009] The existing inverted well technology described above has the following drawbacks. First, the on-site pouring volume for each well inner wall segment is large, the drying period is long, and excavation can only continue after the concrete of each inner wall segment has dried and hardened, thus prolonging the overall construction period of the inverted well. Furthermore, before pouring each inner wall segment, the bottom section of the connecting reinforcement for that layer needs to be inserted into the soil and tied to the connecting reinforcement of the layer above, making the tying process more complicated than normal. Additionally, the side formwork of each segment needs to be supported using diagonal braces or tie bolts, further complicating the process and wasting time and effort. Moreover, when excavating the next layer of soil, care must be taken to avoid the connecting reinforcement of the inner wall segment of the previous layer, further slowing down the excavation process. In summary, the construction process is cumbersome and labor-intensive, and urgently needs improvement. Summary of the Invention

[0010] One technical problem that this invention aims to solve is to provide an inverted well that can shorten the construction period, simplify the construction process, reduce labor intensity, and save labor costs.

[0011] One technical solution of the present invention is to provide an inverted well, which includes an outer wall of the well composed of a ring of jet grouting piles; an L-shaped capping beam is cast at the upper end of the outer wall of the well, the lower convex part of the capping beam is located on the inner side of the outer wall of the well; multiple layers of inner wall segments are cast below the capping beam, and a bottom plate is cast at the lower end of the lowest inner wall segment.

[0012] The lower convex part of the top ring beam is anchored with multiple vertical first connecting bars. The bottom surface of the lower convex part is provided with first filling concrete holes corresponding to the first connecting bars. The bottom end of each first connecting bar extends into the corresponding first filling concrete hole. Each well inner wall segment includes an assembly layer and a post-cast layer located between the assembly layer and the well outer wall. The assembly layer is composed of multiple precast blocks assembled end to end. Each precast block has a baffle on one side and a locking slot on the other side. The locking slot of each precast block locks the baffle of the adjacent precast block.

[0013] Some precast blocks have through-holes for grouting; each precast block includes four longitudinal main bars and three transverse stirrups. The two inner main bars and the inner half of the stirrups are anchored inside the precast block, while the two outer main bars and the outer half of the stirrups are exposed on the outer surface of the precast block.

[0014] Each inner main reinforcement bar is connected to a second splice bar. The upper section of the second splice bar protrudes from the top surface of the precast block, while the lower section is anchored inside the precast block. The bottom surface of the precast block is provided with two second filler concrete holes, and the bottom ends of the two inner main reinforcement bars extend into the corresponding second filler concrete holes. The top surface of the precast block is provided with a filler concrete groove for connecting the post-cast layer and the filler concrete hole of the upper layer. The upper section of the second splice bar of the uppermost precast block is inserted into the first filler concrete hole and is anchored to the bottom section of the first splice bar in the hole by lapping with the post-cast concrete. The upper sections of the second splice bars of other layers of precast blocks are inserted into the second filler concrete hole of the upper layer of precast blocks and are anchored to the bottom section of the inner main reinforcement bar in the hole by lapping with the post-cast concrete.

[0015] Each stirrup is connected to one end of a transverse lap bar, the free end of which protrudes from the precast block baffle. The free end of the lap bar of each precast block overlaps with the outer half of the stirrup of the adjacent precast block. The outer main bars, lap bars and outer half of the stirrups are all anchored in the post-cast concrete layer.

[0016] Another technical problem that this invention aims to solve is to provide a method for constructing inverted wells that can shorten the construction period, simplify construction procedures, reduce labor intensity, and save labor costs.

[0017] One technical solution of the present invention is to provide a method for constructing an inverted well, the steps of which include: first driving a ring of jet grouting piles along the well outline to form the outer wall of the well;

[0018] A L-shaped capping ring beam is constructed at the upper end of the outer wall of the well. The steel cage of the ring beam is tied, the side formwork is erected, and the concrete of the ring beam is poured. During the tying, a pre-embedded sleeve with an opening facing downward is fixed at the lower end of the first connecting bar of the steel cage, thereby forming the first filler concrete hole at the bottom of the beam after pouring.

[0019] Excavate the soil to the height of the first segment, exposing the first concrete filling hole at the bottom of the capping ring beam; then stack the precast blocks one by one, ensuring that the upper section of the second splice bar of each precast block inserts into the first concrete filling hole of the capping ring beam, and that the outer half of the stirrup of each precast block overlaps below the free end of the corresponding lapped bar of the preceding adjacent precast block, and ensuring that the clamp of each precast block presses against the baffle of the preceding adjacent precast block, so that the precast blocks abut against each other end to form an assembly layer; then, through the through... Grouting is injected into the post-cast layer at the height of the assembled layer through the grouting holes, achieving bonding and anchoring between the assembled layer and the outer wall of the well. At the same time, it achieves lap anchoring between the stirrups of each precast block and the lap joint bars of the adjacent precast blocks. After the post-cast layer is filled, grouting continues, allowing the grout to flow into the first filler hole of the upper layer through the filler concrete groove, achieving lap anchoring between the second joint bar of the precast block in this layer and the first joint bar of the upper layer capping ring beam; thus completing the construction of the first well inner wall segment below the capping ring beam.

[0020] Continue excavating the soil to a depth of one segment, exposing the second filler concrete hole at the bottom of the inner wall segment of the upper layer of the well. Then, stack the precast blocks one by one, ensuring that the upper section of the second splice bar of each precast block is inserted into the second filler concrete hole of the upper layer of precast blocks, and that the outer half of the stirrup of each precast block overlaps the free end of the corresponding lap splice bar of the preceding adjacent precast block. Ensure that the snap-fit ​​of each precast block presses against the baffle of the preceding adjacent precast block, so that the precast blocks are joined end to end to form an assembly layer. Then, grout is injected into the post-cast layer at this segment height through the grouting hole to achieve bonding and anchoring between the assembly layer and the outer wall of the well, and at the same time, to achieve lap anchoring between the stirrup of each precast block and the lap splice bar of the adjacent precast block. After the post-cast layer is filled, continue grouting, allowing the grout to flow into the second filler concrete hole of the upper layer along the filler concrete groove, to achieve lap anchoring between the second splice bar of this layer of precast blocks and the inner main reinforcement of the upper layer of precast blocks. This completes the construction of the next inner wall segment of the well.

[0021] Excavate and construct the next layer of the well wall segment in the same manner until the bottom of the well is reached, then tie the bottom slab reinforcement cage and pour the bottom slab concrete.

[0022] Compared with existing technologies, the inverted well and its construction method described in this application have the following advantages.

[0023] Firstly, the technical solution of this application solves the following technical problem: how to connect each individual precast block vertically and horizontally to form a whole row and column with overall strength, and to firmly connect it to the outer wall of the well, under the condition of an upper pressure beam or well wall segment and a lower soil barrier. Because the precast blocks of this application are specially designed, when the precast block is tilted upwards, so that the second connecting bar at the top is inserted into the filling hole of the upper layer in an arc trajectory, the stirrup of the precast block can be overlapped with the connecting bar of the previous precast block, and the clamping mouth of the precast block can be pressed against the baffle of the adjacent precast block simultaneously; that is, the upper, lower, left and right reinforcement overlap is completed in one assembly. Then, grouting is performed on the post-cast layer through the grouting holes penetrating the assembly layer, achieving bonding and anchoring between the assembly layer and the outer wall of the well. Simultaneously, the bonding and anchoring of the stirrups of the precast block and the connecting bars of adjacent precast blocks in the same layer are also achieved. After the post-cast layer is filled with grout, it is poured into the filling holes of the upper layer through the filling concrete groove, achieving lap anchoring of the second connecting bar of the current layer's precast block with the first connecting bar of the upper layer's capping ring beam or the longitudinal main reinforcement of the upper layer's precast block. In other words, a single grouting operation simultaneously solves the bonding and anchoring problems of the upper, lower, left, and right reinforcements, as well as the bonding and anchoring problems between the assembly layer and the outer wall of the well. This allows each precast block in a vertical column and the uppermost capping ring beam to form a longitudinal integral support structure, with sufficient longitudinal strength and stiffness ensured by the lap anchoring of each reinforcement bar. Furthermore, each precast block in a horizontal row also forms a transverse integral support, similarly ensuring sufficient transverse strength and stiffness through the lap anchoring of the reinforcement bars. The overall strength in both vertical and horizontal directions is integrated into a single assembled layer, and the grouting of the post-cast layer also solves the connection between the assembled layer and the outer wall of the well.

[0024] In summary, the inner wall of the inverted well of this invention is excavated layer by layer, assembled piece by piece, and grouted layer by layer to form an integral inner wall, ensuring its overall strength and mechanical properties. Since this structure mainly relies on the assembly of precast blocks, the amount of on-site pouring is greatly reduced, and the amount of wet work is only about one-fifth of the original. Its drying time is significantly reduced, significantly shortening the construction period. Moreover, all the aforementioned connecting bars are integrated within the precast blocks; the process of stacking the precast blocks simultaneously completes the erection of the various reinforcing bars, thus completely eliminating the multiple processes of tying the reinforcing cage, inserting the connecting bars of this layer into the soil, and tying the connecting bars of this layer to the connecting bars of the upper layer, significantly simplifying the construction process. Furthermore, the precast blocks of this structure also objectively serve as side formwork; therefore, only the stacking of each precast block is needed to achieve the desired result. Precast blocks replace the function of side formwork, allowing direct grouting into the subsequent pouring layers. This eliminates the need for the existing method of supporting side formwork with diagonal braces or tie bolts, further simplifying the process. Furthermore, the stacking and assembly of each precast block is convenient; simply inserting the protruding second connecting bar upwards in an arc-shaped trajectory into the upper layer's filler concrete hole quickly completes the connection, reinforcement overlap, and positioning of the precast block with its four adjacent blocks. Moreover, since the longitudinal main reinforcement of each layer of precast blocks is no longer inserted into the soil, there is no need to carefully avoid the longitudinal reinforcement of the upper layer's inner wall segment when excavating the next layer, further improving excavation efficiency. Therefore, this inverted well can shorten the construction period, simplify construction procedures, reduce labor intensity, and save labor costs.

[0025] As an enhancement, a limiting protrusion is provided on the inner side of the top surface of the precast block; in this way, during assembly, the protrusion of the current layer of precast block will lock the previous layer of precast block, thereby accurately positioning the position of the current layer of precast block, improving construction accuracy and the overall strength of the inverted well.

[0026] Preferably, the outer side of the bottom surface of the precast block has a rounded edge. This facilitates the rolling of the precast block during assembly, and the arc-shaped guide of the precast block makes it easier for the second connecting bar at the top to be inserted into the filling hole of the upper layer in an arc shape. Of course, since the steel bar of the second connecting bar itself is elastic, and the diameter of the filling hole is significantly larger than the inserted connecting bar, and the soil is generally relatively soft, the second connecting bar can be inserted into the filling hole of the upper layer in an arc shape with force. However, with the guidance of the rounded edge, the insertion process is easier and more accurate.

[0027] As a further preferred option, the two second connecting bars of each precast block are composed of two vertical segments of a U-shaped bar. The horizontal segment of the U-shaped bar is anchored inside the precast block and tied to the inner half of the upper stirrup of the precast block. The U-shaped bar ensures that there is sufficient lap anchorage length with the steel cage of the precast block, thereby ensuring the strength and firmness of the precast block and the second connecting bar, and thus enhancing the overall longitudinal strength and rigidity.

[0028] As another preferred option, the lap reinforcement of each precast block is composed of the long bars of an L-shaped bar, and the short bars of the L-shaped bar are anchored inside the precast block and tied to the side section of the corresponding stirrup of the precast block; the L-shaped bar ensures that there is sufficient lap anchorage length with the steel cage of the precast block, thereby ensuring the strength and firmness of the precast block and the lap reinforcement, and thus enhancing the overall lateral strength and stiffness.

[0029] As an alternative, each precast layer has four L-shaped concrete slabs distributed at its four corners. One side of each L-shaped concrete slab is engaged with the snap-fit ​​of an adjacent precast block, and the other side of the L-shaped concrete slab abuts against the inner surface of the baffle of another adjacent precast block. An L-shaped steel mesh is provided on the outside of the L-shaped concrete slab. One end of the L-shaped steel mesh overlaps with the lap bar of an adjacent precast block, and the other end overlaps with the outer semicircle of the stirrup of another adjacent precast block. In this way, the connection strength and firmness of two adjacent and perpendicular rows of precast blocks at the corner are ensured, improving the integrity and firmness of the inner wall segment of the well at the same height. Moreover, the above structure is easy to construct. It only requires first assembling the L-shaped steel mesh, then stacking and placing the L-shaped concrete slabs, and simultaneously filling the area between the L-shaped concrete slabs and the corner of the outer wall of the well when pouring the subsequent concrete layer.

[0030] As another preferred option, the transverse bars of the steel mesh of the well bottom slab are provided with upturned elbow bars at both ends. Each elbow bar extends into the second filler concrete hole of the bottommost precast block and is anchored to the bottom section of the inner main bar in the hole by lapping with the post-poured concrete. This makes the construction of the well bottom slab convenient and ensures the connection strength and firmness between the well bottom slab and the bottommost inner wall segment. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the structure of the prefabricated block of the inverted well of the present invention.

[0032] Figure 2 yes Figure 1 A schematic diagram of the structure after being deflected at a certain angle.

[0033] Figure 3 This is a schematic diagram of the steel cage structure of the precast block of the inverted well of the present invention.

[0034] Figure 4 This is a schematic diagram of the structure of the precast block of the inverted well of the present invention with a rounded corner.

[0035] Figure 5 This is a schematic diagram of the structure of the inverted well of the present invention when the prefabricated blocks are assembled into a semi-circular assembly layer.

[0036] Figure 6 This is a schematic diagram of the corner structure of the inverted well of the present invention.

[0037] Figure 7 This is a schematic diagram of the inverted well structure of the present invention viewed from below.

[0038] Figure 8 This is a sectional view of a row of precast blocks of the present invention after being cut open in the plane where the axis of the second concrete filling hole is located (for clarity, the section lines of the row of precast blocks are not marked on this drawing).

[0039] Figure 9 yes Figure 8 A magnified structural diagram of part A in the middle.

[0040] Figure 10 yes Figure 8 A magnified structural diagram of part B.

[0041] Figure 11 This is a cross-sectional structural diagram of the inverted well of the present invention.

[0042] The diagram shows: 1. Jet grouting pile; 2. Top ring beam; 2.1. Lower protrusion; 3. First connecting bar; 4. First filling concrete hole; 5. Assembly layer; 6. Post-cast layer; 7. Baffle; 8. Clamp; 9. Grouting hole; 10. Stirrup; 11. Inner main bar; 12. Outer main bar; 13. Second connecting bar; 14. U-shaped bar; 15. Second filling concrete hole; 16. Filling concrete groove; 17. Lap bar; 18. L-shaped bar; 19. L-shaped concrete slab; 20. L-shaped steel mesh; 21. Limiting protrusion; 22. Arc surface; 23. Bottom plate; 24. Elbow bar. Detailed Implementation

[0043] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] like Figures 1-11 As shown, the inverted well of the present invention includes an outer wall of the well composed of a continuous ring of jet grouting piles 1; the continuous ring of jet grouting piles 1 forms a water-stopping curtain, and longitudinal steel sections are inserted at intervals on the jet grouting piles 1 to enhance rigidity and load-bearing capacity.

[0045] An L-shaped capping beam 2 is cast at the upper end of the outer wall of the well. The main body of the capping beam 2 is cast at the upper end of the outer wall of the well, while the lower protrusion 2.1 of the capping beam 2 is located on the inner side of the outer wall of the well. The reinforcing cage of the capping beam 2 includes vertical first connecting bars 3. The main body of the first connecting bars 3 is anchored to the lower protrusion 2.1 of the capping beam 2. The bottom surface of the lower protrusion 2.1 is provided with first filling concrete holes 4 corresponding to the first connecting bars 3. The bottom end of each first connecting bar 3 extends into the corresponding first filling concrete hole 4.

[0046] Below the capping ring beam 2, multiple well inner wall segments are poured. Each well inner wall segment includes an assembly layer 5 and a post-cast layer 6, with the post-cast layer 6 located between the assembly layer 5 and the outer wall of the well. The assembly layer 5 of each well inner wall segment is composed of multiple precast blocks joined end to end. Each precast block has a baffle 7 on one side and a locking slot 8 on the other side, with the locking slot 8 of each precast block locking the baffle 7 of the adjacent precast block. Some precast blocks have through-holes 9 for grouting the post-cast layer 6; for example, every three precast blocks, that is, every two normal precast blocks, there is a precast block with a through-hole 9.

[0047] Each precast block's steel cage includes four longitudinal main bars and three transverse stirrups 10. The two inner main bars 11 and the inner half of all the stirrups 10 are anchored inside the precast block, while the two outer main bars 12 and the outer half of all the stirrups 10 are exposed on the outer surface of the precast block.

[0048] Each inner main reinforcement bar 11 is connected to a second connecting bar 13. The upper section of the second connecting bar 13 protrudes from the top surface of the precast block, while the lower section is anchored inside the precast block. Specifically, the two second connecting bars 13 of each precast block are composed of two vertical sections of a U-shaped bar 14. The horizontal section of the U-shaped bar 14 is anchored inside the precast block and tied to the inner half of the upper stirrup 10 of the precast block.

[0049] The bottom surface of the precast block is provided with two second concrete filling holes 15, and the bottom ends of the two inner main reinforcement bars 11 of the precast block extend into the corresponding second concrete filling holes 15 respectively; the top surface of the precast block is provided with a concrete filling groove 16 for connecting the post-cast layer 6 and the upper layer concrete filling hole; the upper layer concrete filling hole refers to the first concrete filling hole 4 of the capping ring beam 2 or the second concrete filling hole 15 of the upper layer precast block.

[0050] The upper section of the second connecting bar 13 of the topmost precast block is inserted into the first filler concrete hole 4 and anchored to the bottom section of the first connecting bar 3 in the first filler concrete hole 4 by lapping with the post-poured concrete; the post-poured concrete refers to the concrete material flowing from the post-poured layer 6 into the first filler concrete hole 4 through the filler concrete groove 16. The upper section of the second connecting bar 13 of other layers of precast blocks is inserted into the second filler concrete hole 15 of the upper layer of precast block and anchored to the bottom section of the inner main bar 11 in the second filler concrete hole 15 of the upper layer of precast block by lapping with the post-poured concrete; the post-poured concrete refers to the concrete material flowing from the post-poured layer 6 into the second filler concrete hole 15 of the upper layer of precast block through the filler concrete groove 16.

[0051] Each stirrup 10 is connected to one end of a transverse lap bar 17. The free end of the lap bar 17 protrudes from the precast block baffle 7. That is, the lap bar 17 of each precast block is composed of the long bar of an L-shaped bar 18. The short bar of the L-shaped bar 18 is anchored in the precast block and tied to the side section of the corresponding stirrup 10 of the precast block. The free end of the lap bar 17 of each precast block overlaps with the outer half of the stirrup 10 of the adjacent precast block. The outer main bars 12, lap bars 17 and outer half of stirrups 10 are all anchored in the post-cast concrete layer 6.

[0052] Each layer consists of four rows of precast blocks that are interlocked end to end, while four L-shaped concrete slabs 19 are distributed at the four corners of the same assembly layer 5. Each L-shaped concrete slab 19 is interlocked on one side with the slot 8 of an adjacent precast block, and the other side of the L-shaped concrete slab 19 abuts against the inner surface of the baffle 7 of another adjacent precast block. An L-shaped steel mesh 20 is provided on the outside of the L-shaped concrete slab 19. One end of the L-shaped steel mesh 20 overlaps with the lap bar 17 of an adjacent precast block, and the other end of the L-shaped steel mesh 20 overlaps with the outer semicircle of the stirrup 10 of another adjacent precast block.

[0053] Each precast block has a limiting protrusion 21 on the inner side of its top surface. The outer side of the bottom surface of the precast block has an arc surface 22 (e.g., ...). Figure 4 (As shown). Of course, it is also possible to use a right angle transition directly instead of a rounded surface 22 for the bottom corner of the outer surface of the precast block.

[0054] The bottom end of the inner wall segment of the lowest layer of the well is filled with a well bottom plate 23; the transverse bars of the steel mesh of the well bottom plate 23 are provided with upturned bent bars 24 at both ends. Each bent bar 24 extends into the second filler concrete hole 15 of the lowest layer of the precast block and is anchored to the bottom section of the inner main bar 11 in the second filler concrete hole 15 of the lowest layer of the precast block by lapping with the post-cast concrete. This part of the post-cast concrete refers to the concrete material that will rise up and flow into the second filler concrete hole 15 of the lowest layer of the precast block when the concrete of the well bottom plate 23 is poured.

[0055] The construction method of the inverted well using the present invention comprises the following steps.

[0056] First, drive a ring of jet grouting piles 1 continuously close together along the well outline and insert longitudinal steel sections at intervals to form the outer wall of the well.

[0057] A L-shaped capping ring beam 2 is constructed at the upper end of the outer wall of the well. The steel cage of the ring beam is tied, the side formwork is erected, and the concrete of the ring beam is poured. During the tying, a pre-embedded sleeve with an opening facing downward is fixed at the lower end of the first connecting bar 3 of the steel cage, so that the first filler concrete hole 4 is formed at the bottom surface of the capping ring beam 2 after pouring.

[0058] The soil is excavated to the height of the first segment, exposing the first concrete filling hole 4 on the bottom surface of the capping ring beam 2; then the precast blocks are stacked one by one, so that the upper section of the second splice bar 13 of each precast block is inserted into the first concrete filling hole 4 of the capping ring beam 2, and the outer half of the stirrup 10 of each precast block is lapped below the free end of the corresponding lap splice bar 17 of the previous adjacent precast block, and it is ensured that the locking 8 of each precast block presses against the baffle 7 of the previous adjacent precast block, so that the precast blocks are joined end to end to form the assembly layer 5; then, they are assembled through the entire process. Grouting is injected into the post-cast layer 6 at the height of layer 5 through the grouting hole 9, so as to achieve the bonding and anchoring of the assembled layer 5 with the outer wall of the well. At the same time, the stirrups 10 of each precast block are anchored to the lap bars 17 of the adjacent precast blocks. After the post-cast layer 6 is filled, grouting continues, so that the grout flows into the first lap bar 4 of the upper layer through the filler concrete groove 16, so as to achieve the lap anchoring of the second connecting bar 13 of the precast block in this layer with the first connecting bar 3 of the upper layer capping ring beam 2. Thus, the construction of the first layer of the inner wall of the well below the capping ring beam 2 is completed.

[0059] Continue excavating one section of soil to expose the second concrete filling hole 15 on the bottom surface of the inner wall section of the upper layer of the well. Then, stack the precast blocks one by one, so that the upper part of the second splice bar 13 of each precast block is inserted into the second concrete filling hole 15 of the upper layer of precast blocks, and the outer half of the stirrup 10 of each precast block is lapped below the free end of the corresponding lap splice bar 17 of the previous adjacent precast block. Ensure that the locking 8 of each precast block presses against the baffle 7 of the previous adjacent precast block, so that the precast blocks are joined end to end to form an assembly. Layer 5; then grouting is performed through grouting holes 9 to the post-cast layer 6 at the height of this segment, to achieve bonding and anchoring between the assembled layer 5 and the outer wall of the well, and at the same time to achieve lap anchoring between the stirrups 10 of each precast block and the lap reinforcement 17 of the adjacent precast block. After the post-cast layer 6 is filled, grouting continues, so that the grout flows along the filler concrete groove 16 into the second filler concrete hole 15 of the upper layer, to achieve lap anchoring between the second connecting reinforcement 13 of the precast block in this layer and the inner main reinforcement 11 of the precast block in the upper layer; thus completing the construction of the next layer of the inner wall segment of the well.

[0060] Excavate and construct the next layer of the well wall segment in the same manner until the bottom of the well is reached. Tie the bottom plate steel cage 23 and pour the bottom plate concrete.

[0061] When tying the reinforcing mesh of the well bottom slab 23, the upturned bent bars 24 can be tied at both ends of the transverse bars of the reinforcing mesh, and each bent bar 24 can be inserted into the second filler concrete hole 15 of the bottommost precast block. In this way, when the well bottom slab 23 is poured, the concrete will rise and flow into the second filler concrete hole 15 of the bottommost precast block to form the post-poured concrete in the hole, thereby lapping and anchoring each bent bar 24 to the bottom section of the inner main bar 11 in the second filler concrete hole 15 of the bottommost layer.

Claims

1. An inverted well, comprising an outer wall of the well consisting of a ring of jet grouting piles; an L-shaped capping beam is cast at the upper end of the outer wall of the well, the lower convex part of the capping beam being located on the inner side of the outer wall of the well; multiple layers of inner wall segments are cast below the capping beam, and a bottom plate is cast at the lower end of the lowest inner wall segment. Its features are: The lower convex part of the top ring beam is anchored with multiple vertical first connecting bars. The bottom surface of the lower convex part is provided with first filling concrete holes corresponding to the first connecting bars. The bottom end of each first connecting bar extends into the corresponding first filling concrete hole. Each well inner wall segment includes an assembly layer and a post-cast layer located between the assembly layer and the well outer wall. The assembly layer is composed of multiple precast blocks assembled end to end. Each precast block has a baffle on one side and a locking slot on the other side. The locking slot of each precast block locks the baffle of the adjacent precast block. Some precast blocks have through-holes for grouting; each precast block includes four longitudinal main bars and three transverse stirrups. The two inner main bars and the inner half of the stirrups are anchored inside the precast block, while the two outer main bars and the outer half of the stirrups are exposed on the outer surface of the precast block. Each inner main reinforcement bar is connected to a second splice bar. The upper section of the second splice bar protrudes from the top surface of the precast block, while the lower section is anchored inside the precast block. The bottom surface of the precast block is provided with two second filler concrete holes, and the bottom ends of the two inner main reinforcement bars extend into the corresponding second filler concrete holes. The top surface of the precast block is provided with a filler concrete groove for connecting the post-cast layer and the filler concrete hole of the upper layer. The upper section of the second splice bar of the uppermost precast block is inserted into the first filler concrete hole and is anchored to the bottom section of the first splice bar in the hole by lapping with the post-cast concrete. The upper sections of the second splice bars of other layers of precast blocks are inserted into the second filler concrete hole of the upper layer of precast blocks and are anchored to the bottom section of the inner main reinforcement bar in the hole by lapping with the post-cast concrete. Each stirrup is connected to one end of a transverse lap bar. The free end of the lap bar protrudes from the precast block baffle. The free end of the lap bar of each precast block overlaps with the outer half of the stirrup of the adjacent precast block. The outer main bars, lap bars and outer half of the stirrups are all anchored in the post-cast concrete layer. Each assembly layer has four L-shaped concrete slabs distributed at its four corners. One side of each L-shaped concrete slab is engaged with the slot of an adjacent precast block, and the other side of the L-shaped concrete slab abuts against the inner surface of the baffle of another adjacent precast block. An L-shaped steel mesh is provided on the outside of the L-shaped concrete slab. One end of the L-shaped steel mesh overlaps with the lap bar of an adjacent precast block, and the other end of the L-shaped steel mesh overlaps with the outer semicircle of the stirrup of another adjacent precast block.

2. The inverted well according to claim 1, characterized in that: A limiting protrusion is provided on the inner side of the top surface of the precast block.

3. The inverted well according to claim 1, characterized in that: The outer side of the bottom surface of the precast block is provided with an arc surface.

4. The inverted well according to claim 1, characterized in that: The two second connecting bars of each precast block are composed of two vertical segments of a U-shaped bar, the horizontal segment of which is anchored inside the precast block and tied to the inner half of the upper stirrup of the precast block.

5. The inverted well according to claim 1, characterized in that: The lap reinforcement of each precast block is composed of the long bars of an L-shaped bar, and the short bars of the L-shaped bar are anchored inside the precast block and tied to the side section of the corresponding stirrup of the precast block.

6. The inverted well according to claim 1, characterized in that: The transverse bars of the steel mesh in the bottom slab of the well are provided with upturned bent bars at both ends. Each bent bar extends into the second supplementary concrete hole of the lowest layer of precast block and is anchored to the bottom section of the inner main bar in the hole by lapping with the post-poured concrete.

7. A construction method for an inverted well, characterized in that: The steps include: First, drive a ring of jet grouting piles along the well outline to form the outer wall of the well; A L-shaped capping ring beam is constructed at the upper end of the outer wall of the well. The steel cage of the ring beam is tied, the side formwork is erected, and the concrete of the ring beam is poured. During the tying, a pre-embedded sleeve with an opening facing downward is fixed at the lower end of the first connecting bar of the steel cage, thereby forming the first filler concrete hole at the bottom of the beam after pouring. Excavate the soil to the height of the first segment, exposing the first concrete filling hole at the bottom of the capping ring beam; then stack the precast blocks one by one, ensuring that the upper section of the second splice bar of each precast block inserts into the first concrete filling hole of the capping ring beam, and that the outer half of the stirrup of each precast block overlaps below the free end of the corresponding lapped bar of the preceding adjacent precast block, and ensuring that the clamp of each precast block presses against the baffle of the preceding adjacent precast block, so that the precast blocks abut against each other end to form an assembly layer; then, through the through... Grouting is injected into the post-cast layer at the height of the assembled layer through the grouting holes, achieving bonding and anchoring between the assembled layer and the outer wall of the well. At the same time, it achieves lap anchoring between the stirrups of each precast block and the lap joint bars of the adjacent precast blocks. After the post-cast layer is filled, grouting continues, allowing the grout to flow into the first filler hole of the upper layer through the filler concrete groove, achieving lap anchoring between the second joint bar of the precast block in this layer and the first joint bar of the upper layer capping ring beam; thus completing the construction of the first well inner wall segment below the capping ring beam. Continue excavating the soil to a depth of one segment, exposing the second filler concrete hole at the bottom of the inner wall segment of the upper layer of the well. Then, stack the precast blocks one by one, ensuring that the upper section of the second splice bar of each precast block is inserted into the second filler concrete hole of the upper layer of precast blocks, and that the outer half of the stirrup of each precast block overlaps the free end of the corresponding lap splice bar of the preceding adjacent precast block. Ensure that the snap-fit ​​of each precast block presses against the baffle of the preceding adjacent precast block, so that the precast blocks are joined end to end to form an assembly layer. Then, grout is injected into the post-cast layer at this segment height through the grouting hole to achieve bonding and anchoring between the assembly layer and the outer wall of the well, and at the same time, to achieve lap anchoring between the stirrup of each precast block and the lap splice bar of the adjacent precast block. After the post-cast layer is filled, continue grouting, allowing the grout to flow into the second filler concrete hole of the upper layer along the filler concrete groove, to achieve lap anchoring between the second splice bar of this layer of precast blocks and the inner main reinforcement of the upper layer of precast blocks. This completes the construction of the next inner wall segment of the well. Excavate and construct the next layer of the well wall segment in the same manner until the bottom of the well is reached, then tie the bottom slab reinforcement cage and pour the bottom slab concrete.

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