Method of construction of precast assembled circular shaft lining

Abstract

The application relates to a construction method of a prefabricated assembled circular well wall, which comprises the following steps: a, transporting the prefabricated well wall (1) to the site after prefabricating the well wall (1) in a factory; b, layer-by-layer excavation, digging to the depth of the first section of the prefabricated well wall (1), then arranging soil nails (5) along the circumference and anchoring; c, installing annular ribs (6); d, assembling the prefabricated well wall (1) into a ring shape, hanging the prefabricated well wall (1) on the horizontal annular ribs (6) and grouting; e, continuing to dig, connecting vertical ribs (7) with the annular ribs (6), then sequentially hanging the prefabricated well wall (1) on the annular ribs (6) and grouting; f, installing longitudinal connecting components (4) in longitudinal reserved holes (2) and grouting; g, continuing to dig, repeating e and f until completion; h, pouring a bottom plate (13). The structure is constructed layer by layer, the process is simplified, the construction speed is high, and the cost is low. The problems of long construction period, complex process, long exposure time of a foundation pit and high risk of the cast-in-place well wall structure construction method are solved.

Description

TECHNICAL FIELD

[0001] The application relates to a construction method of a prefabricated and assembled circular shaft wall and belongs to the technical field of underground engineering construction. BACKGROUND

[0002] With the acceleration of urbanization development, land resources are increasingly scarce, and the situation of oversupply and high prices of ground space has appeared in some areas. The development and utilization of underground space provide a possibility for relieving the tension of urban land, improving the urban environment and traffic conditions, and energy saving and environmental protection.

[0003] The vertical shaft type underground structure can be applied to the vertical connecting channel and cylindrical foundation of underground spaces such as underground garage, underground water storage tank, underground granary, underground storage space and tunnel. However, due to the need of large excavation of earthwork, the earthwork is taken out and the slope is formed, and the construction operation area is much larger than the land occupation area of the building itself, which is difficult to realize for some urban areas with limited construction sites.

[0004] At present, the cast-in-place shaft wall structure construction is usually used for the large vertical shaft wall structure of underground space. The construction period is long, the wet operation process is complex, the foundation pit groove wall is exposed for a long time, the safety risk is large, and the quality is difficult to guarantee, which cannot practically meet the actual demand. SUMMARY

[0005] The technical problem to be solved by the application is that the cast-in-place shaft wall structure construction method has a long construction period, a complex process, a long exposure time of the foundation pit, and a large risk.

[0006] The technical scheme adopted by the application to solve the technical problem is: a construction method of a prefabricated and assembled circular shaft wall, comprising the following steps:

[0007] a. The shape and size of the prefabricated shaft wall are designed according to the structural size of the circular vertical shaft, the geological conditions of the construction and the surrounding environmental factors, and the prefabricated shaft wall is transported to the construction site after being prefabricated in a factory;

[0008] b. The construction positioning and line laying are performed, and the earthwork is excavated layer by layer. After the first section of the prefabricated shaft wall is excavated to a depth, soil nails are arranged along the circumference at intervals according to the geological conditions, the soil nails are hammered or drilled into the soil layer, and then cement slurry is injected into the soil nails to anchor the soil nails in the soil layer;

[0009] c. The annular rib is installed on the soil nail;

[0010] d. The prefabricated shaft wall is assembled into a ring shape, the prefabricated shaft wall is hung on the horizontal annular rib in sequence, and fine stone concrete or cement mortar is poured on the outer side of the shaft wall;

[0011] e. Continue digging downwards to the depth of the precast well wall, connect the vertical reinforcement to the upper ring reinforcement, and install the ring reinforcement. The precast well wall is then hung on the ring reinforcement in sequence, and fine stone concrete or cement mortar is pressure-poured into the outside of the well wall.

[0012] f. Install longitudinal connecting components sequentially in the longitudinal reserved holes that penetrate the precast well wall, and inject micro-expansion cement grout after completion;

[0013] g. Continue digging downwards, repeating steps e and f to construct downwards to the foundation, and complete the installation of the shaft wall structure;

[0014] h. Construct the bottom slab of the vertical shaft.

[0015] In the above method, the two ends of the precast well wall in step a are respectively provided with longitudinal protrusions and longitudinal grooves, so that the left and right adjacent precast well walls are connected into a ring through the longitudinal protrusions and longitudinal grooves.

[0016] Furthermore, in step a of the above method, the upper and lower end faces of the precast well wall are provided with matching annular protrusions and annular grooves, so that the upper and lower precast well walls can be connected through the annular protrusions and annular grooves.

[0017] Furthermore, in step a of the above method, pre-embedded reinforcing bars are provided on the outer wall of the precast well wall, and the precast well wall is sequentially hung on the horizontal annular reinforcing bars through the pre-embedded reinforcing bars.

[0018] Furthermore, in the above method, the pre-embedded reinforcement in step a is a T-shaped structure, and the number of pre-embedded reinforcements on each prefabricated well wall is [number], arranged in a rectangular shape.

[0019] In the above method, the excavation diameter in step b is 100-200 mm larger than the structural dimensions of the shaft.

[0020] Furthermore, in step f of the above method, the cavities of the longitudinal convex groove and the longitudinal concave groove, as well as the annular convex groove and the annular concave groove, are also simultaneously injected with micro-expansion cement slurry.

[0021] In the above method, after the prefabricated well wall is assembled into a ring, water-stop strips are installed on the inner and outer sides of the adjacent joints of the well wall. The prefabricated well wall is connected longitudinally through an annular protrusion and an annular groove, and water-stop strips are installed on the inner and outer sides of the adjacent joints of the well wall.

[0022] In the above method, the longitudinally adjacent prefabricated well walls are joined by staggered joints, and the longitudinal reserved holes of the two longitudinally adjacent prefabricated well walls are connected.

[0023] Furthermore, in the above method, the distance from the center of the outermost longitudinal reserved hole of the prefabricated well wall to its end face is half the center distance between the two longitudinal reserved holes.

[0024] The beneficial effects of this invention are as follows: The circular well wall structure constructed by this method is assembled by sequentially and interlocking prefabricated well walls. The prefabricated well walls are connected into a ring shape using connectors, and adjacent prefabricated well walls are joined together using longitudinal connecting components. The pre-embedded reinforcing bars on the prefabricated well walls are fixed by placing them on the ring-shaped reinforcing bars attached to soil nails, and then grouting is used for filling. This method prefabricates the well walls in sections in the factory according to design requirements, requiring only hoisting and assembly on site. This reduces the exposure time of the vertical shaft foundation pit excavation and retaining structure, simplifies the complex process of wet operations, reduces the labor intensity of workers, makes project quality easier to control, accelerates construction, reduces costs, and is environmentally friendly. Furthermore, this method, which uses centralized prefabrication and on-site assembly, effectively ensures construction quality, shortens the construction period, and has good social and economic benefits. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the vertical shaft structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the cross-sectional structure of the connection between the upper and lower prefabricated well walls of the present invention.

[0027] Figure 3 This is a schematic diagram of the upper and lower prefabricated well wall connection structure of the present invention.

[0028] Figure 4 For the present invention Figure 2 Enlarged schematic diagram of the structure at point I.

[0029] Figure 5 For the present invention Figure 2 Enlarged schematic diagram of the structure at point III.

[0030] Figure 6 This is a schematic diagram of the cross-section of the present invention.

[0031] Figure 7 This is a top view of the structure of the present invention.

[0032] Figure 8 For the present invention Figure 7 Enlarged schematic diagram of the structure at point II.

[0033] The markings in the diagram are: 1 Precast well wall, 2 Longitudinal reserved hole, 3 Embedded reinforcement, 4 Longitudinal connecting component, 5 Soil nail, 6 Annular reinforcement, 7 Vertical reinforcement, 8 Water-stop strip, 9 Annular groove, 10 Annular groove, 11 Longitudinal groove, 12 Longitudinal groove, 13 Base plate. Detailed Implementation

[0034] The invention will be further described below with reference to the accompanying drawings.

[0035] like Figures 1 to 8 As shown, a construction method for a prefabricated circular well wall according to the present invention includes the following steps:

[0036] a. The shape and size of the precast shaft wall 1 are designed according to the structural dimensions of the circular shaft, the geological conditions of the construction site and the surrounding environmental factors, and then precast in the factory and transported to the construction site.

[0037] b. Construction positioning and layout, layered excavation of earthwork. After excavating to the depth of the first section of precast well wall 1, soil nails 5 are laid out at intervals around the perimeter according to geological conditions. They are driven into the soil layer by hammering or drilling. Then, cement grout is injected in sequence to anchor the soil nails 5 in the soil layer.

[0038] c. Install ring reinforcement 6 on soil nail 5;

[0039] d. Assemble the precast well wall 1 into a ring. Hang the precast well wall 1 on the horizontal ring reinforcement 6 in sequence. Pressure grout fine stone concrete or cement mortar on the outside of the well wall.

[0040] e. Continue digging downwards to the depth of the precast well wall 1, connect the vertical reinforcement 7 to the upper ring reinforcement 6, and install the ring reinforcement 6. The precast well wall 1 is then hung on the ring reinforcement 6 in sequence, and fine stone concrete or cement mortar is pressure-poured into the outside of the well wall.

[0041] f. Install longitudinal connecting components 4 sequentially in the longitudinal reserved holes 2 that penetrate the precast well wall 1, and inject micro-expansion cement grout after completion;

[0042] g. Continue digging downwards, repeating steps e and f to construct downwards to the base, and complete the installation of the circular well wall structure;

[0043] h. Construct the bottom slab 13 of the well. Those skilled in the art will understand that the circular well wall in this method is mainly assembled by splicing several prefabricated well walls 1 longitudinally and circumferentially. Step a is mainly the preparation stage; in practice, suitable prefabricated well walls 1 are first made according to the design data and delivered to the site for easy assembly construction. Step b: Excavation of the foundation pit. The first excavation depth is determined according to the height of the prefabricated well wall 1. Soil nails 5 are arranged at intervals around the perimeter according to geological conditions. They are driven into the soil layer by hammering or drilling, and then cement grout is injected sequentially to anchor the soil nails 5 in the soil layer. The setting of the soil nails 5 enables the later connection between the circular well wall structure and the soil layer. Preferably, the soil nails 5 are made of… Made of steel pipe, 1000-2000mm in length, with a conical end for insertion into the soil, and soil nails 5 are equipped with... The step c is mainly to install the annular rib 6 on the soil nail 5, and the upper end surface of the soil nail 5 is preferably coplanar, so that the annular rib 6 is horizontally arranged. The annular rib 6 is mainly used for supporting the prefabricated shaft wall 1, and the annular rib 6 is preferably welded with the soil nail 5. The step d is mainly to install the prefabricated shaft wall 1, and the prefabricated shaft wall 1 is first assembled into a ring shape, and then the assembled ring-shaped prefabricated shaft wall 1 is hung on the horizontal annular rib 6 in sequence, and the fine stone concrete or cement mortar is injected under pressure on the outer side of the shaft wall, that is, the fine stone concrete or cement mortar is injected under pressure in the gap between the shaft wall and the inner wall of the foundation pit, so as to realize the fixation of the prefabricated shaft wall 1. The step e is to install the annular rib 6 by digging downward, and the vertical rib 7 is connected with the upper annular rib 6, and the annular rib 6 is continuously installed at the lower part of the vertical rib 7, and the prefabricated shaft wall 1 is hung on the annular rib 6 in sequence, and the C20 fine stone concrete or cement mortar is injected under pressure on the outer side of the shaft wall, so as to complete the installation and fixation of the two-layer prefabricated shaft wall 1. In order to reduce the amount of soil nails 5, the vertical rib 7 is preferably arranged in the structure, the annular rib 6 on the outer side of each layer of prefabricated shaft wall 1 is connected into a whole to form a reinforced skeleton, and the stability of the structure is maintained after the grouting on the outer side of the prefabricated shaft wall 1. And the structure actually only needs to anchor a circle of soil nails 5 on the uppermost layer for supporting the annular rib 6 on the uppermost layer, and the annular rib 6 on the lower layer is directly connected through the vertical rib 7. In the step f, in order to ensure the connection strength of the upper and lower prefabricated shaft walls 1, the longitudinal connecting member 4 is preferably arranged at intervals with the longitudinal reserved hole 2, and the gap is filled with cement mortar. Since the longitudinal connecting member 4 is arranged in the longitudinal reserved hole 2 from top to bottom, the length of the longitudinal connecting member 4 is relatively long, in order to facilitate installation and reduce cost, the longitudinal connecting member 4 is preferably a steel bar or a steel pipe, and is actually connected into one by screwing or welding. The steps e and f are repeated to the bottom according to the depth of the circular shaft wall, and the installation of the shaft wall structure is completed. Finally, the step h is performed to pour the bottom plate 13 of the shaft, and the pouring of the cement mortar is completed. The cement mortar is preferably micro-expanding cement.

[0044] Preferably, the two ends of the prefabricated shaft wall 1 in the step a of the above method are respectively provided with longitudinal convex grooves 11 and longitudinal concave grooves 12, so that the left and right adjacent prefabricated shaft walls 1 are connected into a ring shape through the longitudinal convex grooves 11 and the longitudinal concave grooves 12. Those skilled in the art can understand that the connecting member of the structure is preferably the longitudinal convex grooves 11 and the longitudinal concave grooves 12, and the longitudinal convex grooves 11 and the longitudinal concave grooves 12 are respectively arranged on the two end surfaces of the prefabricated shaft wall 1, and the longitudinal convex grooves 11 are clamped into the longitudinal concave grooves 12 of the adjacent prefabricated shaft wall 1 to realize the circumferential fixation of the prefabricated shaft wall 1, that is, the left and right adjacent prefabricated shaft walls 1 can be connected into a ring shape.

[0045] Preferably, the upper and lower end faces of the prefabricated shaft wall 1 in step a of the above method are provided with matching annular protrusions 9 and annular recesses 10, so that the upper and lower prefabricated shaft walls 1 can be connected through the annular protrusions 9 and annular recesses 10. Those skilled in the art can understand that the structure is also connected through the annular protrusions 9 and annular recesses 10 between the two longitudinally adjacent prefabricated shaft walls 1, so that the upper and lower and left and right of the two adjacent prefabricated shaft walls 1 are connected through the recesses and protrusions, improving the safety and construction quality of the shaft construction.

[0046] Preferably, the outer wall of the prefabricated shaft wall 1 in step a of the above method is provided with a pre-embedded rib 3, and the prefabricated shaft wall 1 is hung on the horizontal annular rib 6 through the pre-embedded rib 3. Those skilled in the art can understand that, in order to facilitate the connection of the prefabricated shaft wall 1 and the annular rib 6, the method preferably provides the outer wall of the prefabricated shaft wall 1 with a pre-embedded rib 3, and the prefabricated shaft wall 1 is hung on the horizontal annular rib 6 through the pre-embedded rib 3 to realize the connection of the prefabricated shaft wall 1 and the annular rib 6.

[0047] Preferably, the pre-embedded rib 3 in step a of the above method is in T-shaped structure, and the number of the pre-embedded rib 3 on each prefabricated shaft wall 1 is four, and arranged in a rectangular shape. Those skilled in the art can understand that, in order to facilitate the hanging of the prefabricated shaft wall 1 on the annular rib 6, the pre-embedded rib 3 is preferably in T-shaped structure, and the number of the pre-embedded rib 3 on each prefabricated shaft wall 1 is four, and arranged in a rectangular shape. This structure is provided with two horizontally arranged annular ribs 6 spaced apart on the outer wall of each layer of prefabricated shaft wall 1.

[0048] Preferably, the diameter of the excavation in step b of the above method is greater than 100-200mm than the structural size of the shaft. Those skilled in the art can understand that, in order to facilitate the installation of the prefabricated shaft wall 1, the method preferably excavates a diameter greater than 100-200mm than the structural size of the shaft.

[0049] Preferably, the cavities of the longitudinal protrusions 11 and longitudinal recesses 12, and the annular protrusions 9 and annular recesses 10 in step f of the above method are also injected with micro-expanding cement slurry at the same time. Those skilled in the art can understand that the cavities are sealed on both sides by the water stop rubber strip 8, and in order to ensure the overall structural strength of the shaft, the cavities of the longitudinal protrusions 11 and longitudinal recesses 12, and the annular protrusions 9 and annular recesses 10 are preferably injected with micro-expanding cement slurry at the same time, realizing the connection and fixation of the adjacent prefabricated shaft walls 1.

[0050] Preferably, in the above method, after the prefabricated well wall 1 is assembled into a ring, a waterproof rubber strip 8 is installed on the inner and outer sides of the adjacent joints of the well wall, and the prefabricated well wall 1 is connected in the longitudinal direction by the annular convex groove 9 and the annular concave groove 10. Those skilled in the art will understand that, in order to ensure the integrity of the entire well wall, grouting is actually performed at the connection between the longitudinal convex groove 11 and the longitudinal concave groove 12 and the connection between the annular convex groove 9 and the annular concave groove 10, and in order to form a closed cavity inside, the structure is preferably filled with a waterproof rubber strip 8 on the inner and outer sides of the connection between the longitudinal convex groove 11 and the longitudinal concave groove 12 and the connection between the upper and lower prefabricated well walls 1, thereby improving the waterproof performance and integrity of the shaft.

[0051] Preferably, in the above method, the longitudinal adjacent prefabricated well walls 1 are connected by staggered joints, and the longitudinal reserved holes 2 of the two adjacent prefabricated well walls 1 are connected. Those skilled in the art will understand that, since the longitudinal reserved holes 2 are uniformly arranged along the middle part of the prefabricated well wall 1, the structure is connected by staggered joints during actual longitudinal splicing to ensure the structural strength and avoid stress concentration after grouting, and the longitudinal reserved holes 2 of the upper and lower prefabricated well walls 1 need to be connected, the longitudinal connecting member 4 is inserted into the hole, and then cement slurry is poured into the longitudinal reserved hole 2 to effectively fix the steel bars or steel pipes of the longitudinal connecting member 4, prevent them from moving up and down, and improve the adhesion between the steel bars or steel pipes and the cement slurry. The longitudinal connecting member 4 and the poured cement slurry column body connect the prefabricated well walls 1 to each other, thereby improving the overall rigidity of the well wall.

[0052] Preferably, in the above method, the distance from the center of the outermost longitudinal reserved hole 2 of the prefabricated well wall 1 to the end surface is half the distance between the centers of the two longitudinal reserved holes 2. Those skilled in the art will understand that, in order to ensure that the longitudinal reserved holes 2 of the upper and lower adjacent prefabricated well walls 1 are always opposite after the left and right adjacent prefabricated well walls 1 are spliced, the distance from the center of the outermost longitudinal reserved hole 2 of the prefabricated well wall 1 to the end surface is half the distance between the centers of the two longitudinal reserved holes 2, that is, the longitudinal reserved holes 2 are always arranged at equal distances after the longitudinal convex groove 11 and the longitudinal concave groove 12 are spliced.

Claims

1. A method of constructing a precast segmental circular wall, characterised by The method comprises the following steps: a. Design the shape and size of the prefabricated shaft wall (1) according to the structural size of the circular shaft, the geological conditions and the surrounding environment factors of the construction, and prefabricate the shaft wall (1) in the factory and then transport the shaft wall (1) to the construction site; b. Perform construction positioning and layering excavation of earthwork, and after the first section of the prefabricated shaft wall (1) is excavated to the depth, soil nails (5) are arranged along the circumference at intervals according to the geological conditions, the soil nails (5) are hammered or drilled into the soil layer, and then cement slurry is injected into the soil nails (5) to anchor the soil nails (5) in the soil layer; c. Install the annular rib (6) on the soil nail (5); d. Assemble the prefabricated shaft wall (1) into a ring shape, the prefabricated shaft wall (1) is hung on the horizontal annular rib (6) in sequence, and fine stone concrete or cement mortar is injected into the outer side of the shaft wall under pressure; e. Continue to excavate the soil, after the prefabricated shaft wall (1) is excavated to the depth, the vertical rib (7) is connected with the upper layer of the annular rib (6), the annular rib (6) is installed, the prefabricated shaft wall (1) is hung on the annular rib (6) in sequence, and fine stone concrete or cement mortar is injected into the outer side of the shaft wall under pressure; f. Install the longitudinal connecting member (4) in the longitudinal reserved hole (2) of the prefabricated shaft wall (1) in sequence, and then inject the micro-expanding cement slurry after completion; g. Continue to excavate the soil, repeat steps e and f, and excavate to the bottom of the shaft to complete the installation of the circular shaft wall structure; h. Perform shaft bottom slab (13) pouring construction; In step a, the two ends of the prefabricated shaft wall (1) are respectively provided with longitudinal convex grooves (11) and longitudinal concave grooves (12), so that the left and right adjacent prefabricated shaft walls (1) are connected into a ring shape through the longitudinal convex grooves (11) and the longitudinal concave grooves (12); in step a, the upper and lower end faces of the prefabricated shaft wall (1) are provided with matched annular convex grooves (9) and annular concave grooves (10), so that the upper and lower prefabricated shaft walls (1) are connected through the annular convex grooves (9) and the annular concave grooves (10); in step a, the outer wall of the prefabricated shaft wall (1) is provided with a pre-embedded rib (3), and the prefabricated shaft wall (1) is hung on the horizontal annular rib (6) in sequence through the pre-embedded rib (3); after the prefabricated shaft wall (1) is assembled into a ring shape, the water stop rubber strips (8) are installed in the inner and outer sides of the adjacent joints of the shaft wall, the longitudinal prefabricated shaft walls (1) are connected through the annular convex grooves (9) and the annular concave grooves (10), and the water stop rubber strips (8) are installed in the inner and outer sides of the adjacent joints of the shaft wall; the longitudinal adjacent prefabricated shaft walls (1) are connected in a staggered joint manner, and the longitudinal reserved holes (2) of the two longitudinal adjacent prefabricated shaft walls (1) are communicated; the distance from the center of the outermost longitudinal reserved hole (2) of the prefabricated shaft wall (1) to the end face is half of the distance between the centers of the two longitudinal reserved holes (2); in step a, the pre-embedded rib (3) is in a T-shaped structure, and the number of the pre-embedded rib (3) on each prefabricated shaft wall (1) is four, which are arranged in a rectangular shape.

2. A method of constructing a precast segmental circular wall as defined in claim 1, wherein: In step b, the diameter of the excavation is greater than 100-200 mm than the structural size of the shaft.

3. A method of constructing a precast segmental circular wall as defined in claim 1, wherein: In step f, the cavities of the longitudinal convex grooves (11) and the longitudinal concave grooves (12), the annular convex grooves (9) and the annular concave grooves (10) are also synchronously injected with the micro-expanding cement slurry.

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