Water-rich loess stratum rectangular shaft construction structure

Abstract

The utility model discloses a rectangular shaft construction structure for a water-rich loess stratum, which relates to the technical field of shaft construction and comprises a locking ring beam, a rectangular shaft area is arranged on the inner side of the locking ring beam, a supporting structure is arranged on the inner side of the rectangular shaft area, and a reinforced concrete beam plate is arranged on the inner side of the supporting structure. And the reinforced concrete beam slab and the supporting structure are anchored together with the surrounding stable soil body by adopting a pre-stressed anchor rod. According to the utility model, the construction is carried out by adopting a method of hanging the well wall upside down, and a fender post and an inner support are not needed to reinforce the stratum, so that the piling vibration disturbance in the construction does not exist, the sedimentation influence on surrounding buildings and underground pipelines is reduced, and the influence on the surrounding buildings is small; and construction of fender posts such as bored piles is not needed, stratum disturbance before excavation of the foundation pit is reduced, two-time disturbance is changed into one-time disturbance, the characteristics of undisturbed soil can be well kept, and the soil body is more stable.

Description

Technical Field

[0001] The utility model relates to the technical field of shaft construction, in particular to a rectangular shaft construction structure in a water-rich loess stratum. Background Technique

[0002] With the acceleration of the urbanization process and the continuous development of infrastructure construction, the development and utilization of underground space have become an important trend in urban development. To increase the construction operation surface of underground projects or meet the functional requirements such as underground space ventilation, a large number of shaft projects will be built in underground engineering construction. The excavation and support structure construction of shafts are crucial links in the shaft construction process, which have important impacts on multiple aspects such as project quality, construction efficiency, and environmental protection.

[0003] Loess has characteristics such as obvious structure, strong water permeability, collapsibility, and developed vertical joints. There are risks such as water leakage, large deformation, block falling, and collapse in constructing shafts in a water-rich loess stratum. The sudden instability of the surrounding rock caused by collapsibility in a short time threatens the construction safety of shafts in a water-rich loess stratum. The shaft construction project has high risks and great difficulties, is prone to causing traffic jams, and has a great impact on the settlement and deformation of surrounding buildings and underground pipelines.

[0004] Therefore, how to provide a rectangular shaft construction structure in a water-rich loess stratum, and use the inverted well wall method to construct the shaft, which can better maintain the characteristics of the original soil and the soil body is more stable, has become a technical problem that needs to be solved urgently by those skilled in the art. Content of the Utility Model

[0005] The purpose of the utility model is to provide a rectangular shaft construction structure in a water-rich loess stratum to solve the problems of large deformation, block falling, and collapse easily occurring in the construction of shafts in a water-rich loess stratum.

[0006] To solve the above technical problems, the utility model adopts the following technical solutions:

[0007] A rectangular shaft construction structure in a water-rich loess stratum of the utility model includes a collar ring beam. The inner side of the collar ring beam is a rectangular shaft area. A support structure is arranged inside the rectangular shaft area. A reinforced concrete beam and slab are arranged inside the support structure. The reinforced concrete beam and slab and the support structure are anchored together with the surrounding stable soil body by prestressed anchor rods.

[0008] Preferably, the support structure includes grouting anchor pipes, steel grids, advanced small pipes, steel bar meshes, and cross braces; the steel grids are arranged along the inner wall of the rectangular shaft area, and two groups of the steel grids on opposite surfaces are connected by the cross braces; the steel bar meshes are respectively laid on the inner and outer sides of the steel grids, and the steel bar meshes are connected to the steel grids by tying. After the support structure is installed in place, shotcrete is sprayed; the input ends of the grouting anchor pipes and the advanced small pipes are communicated with an external grouting pipe, and the output ends of the grouting anchor pipes and the advanced small pipes are inserted into the surrounding rock mass.

[0009] Preferably, multiple grouting anchor pipes and multiple advanced small pipes are both arranged circumferentially along the excavation contour line and obliquely inserted into the surrounding rock mass.

[0010] Preferably, the lock head ring beam is provided with lock head ring beam steel bars, and the lock head ring beam is a cast-in-place rectangular concrete structure.

[0011] Preferably, the lock head ring beam steel bars and the first set of steel grids located below are cast simultaneously.

[0012] Preferably, a water retaining wall is built on the top of the lock head ring beam, and the water retaining wall is at least 500 mm higher than the natural ground surface.

[0013] Compared with the prior art, the beneficial technical effects of the present utility model are as follows:

[0014] The rectangular shaft construction structure in a water-rich loess stratum of the present utility model adopts the inverted shaft wall method for construction, and there is no need to adopt retaining piles and internal supports to reinforce the stratum. Therefore, there is no pile driving vibration disturbance during construction, the settlement influence on surrounding buildings and underground pipelines is reduced, and the influence on surrounding buildings is small; moreover, there is no need to construct retaining piles such as bored piles, reducing the stratum disturbance before foundation pit excavation, changing from two disturbances to one disturbance, being able to better maintain the characteristics of the original soil, and the soil body is more stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The present utility model will be further described below in conjunction with the drawings.

[0016] Figure 1 It is a schematic diagram of the rectangular shaft construction structure in a water-rich loess stratum of the present utility model;

[0017] Figure 2 It is a top view of the shaft of the present utility model;

[0018] Figure 3 It is a schematic diagram of the lock head ring beam steel bar structure of the present utility model;

[0019] Figure 4 It is a schematic diagram of the lock head ring beam structure of the present utility model;

[0020] Figure 5 Schematic diagram of the shaft excavation structure of the present utility model;

[0021] Figure 6 Schematic diagram of the anchorage of the support structure of the present utility model;

[0022] Figure 7 Schematic diagram of the support structure of the present utility model.

[0023] Explanation of reference numerals: 1, collar ring beam; 2, support structure; 3, reinforced concrete beam and slab; 4, prestressed anchor rod; 5, tunnel; 101, collar ring beam steel bars; 201, grouting anchor pipe; 202, steel grid; 203, advanced small pipe; 204, steel mesh; 205, cross brace. Detailed implementation manners

[0024] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present utility model clearer, the present utility model will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present utility model and are not used to limit the present utility model.

[0025] As Figure 1-7 shown, a rectangular shaft construction structure in a water-rich loess stratum includes a collar ring beam 1. The inner side of the collar ring beam 1 is a rectangular shaft area. A support structure 2 is arranged inside the rectangular shaft area. A reinforced concrete beam and slab 3 is arranged inside the support structure 2. The reinforced concrete beam and slab and the support structure 2 are anchored to the surrounding stable soil mass by prestressed anchor rods 4.

[0026] Specifically, the support structure 2 includes grouting anchor pipes 201, steel grids 202, advanced small pipes 203, steel meshes 204 and cross braces 205; the steel grids 202 are arranged along the inner wall of the rectangular shaft area, and two groups of the steel grids 202 on the opposite surfaces are connected by the cross braces 205; the steel meshes 204 are respectively laid on the inner and outer sides of the steel grids 202, and the steel meshes 204 are connected to the steel grids 202 by binding. After the support structure 2 is installed in place, concrete is sprayed; the input ends of the grouting anchor pipes 201 and the advanced small pipes 203 are communicated with an external grouting pipe, and the output ends of the grouting anchor pipes 201 and the advanced small pipes 203 are inserted into the surrounding rock mass.

[0027] Specifically, multiple grouting anchor pipes 201 and multiple advanced small pipes 203 are both arranged circumferentially along the excavation contour line and obliquely inserted into the surrounding rock mass; the grouting anchor pipes 201 and the advanced small pipes 203 improve the structural strength of the surrounding rock mass through grouting.

[0028] Specifically, a locking ring beam steel bar 101 is arranged in the locking ring beam 1, and the locking ring beam 1 is a cast-in-place rectangular concrete structure; the formwork used during casting is assembled from a combination steel formwork with tight joints, and square wood is used on the outside of the formwork for reinforcement and support to ensure its stability.

[0029] Specifically, the locking ring beam reinforcement 101 is cast simultaneously with the first steel grating 202 located below; the integrity is better and the structural strength is higher.

[0030] Specifically, a retaining wall is built on the top of the locking ring beam 1, and the retaining wall is at least 500mm above the natural ground; after the cast locking ring beam 1 reaches 70% of the design strength, the retaining wall is built to ensure the structural strength and play a reinforcing and waterproofing role.

[0031] The construction process of this utility model is as follows:

[0032] First, construction preparation and measurement: investigate and deal with pipelines, thoroughly clean the construction site, remove obstacles and debris, level the site, and conduct pre-pit precipitation to ensure water-free construction;

[0033] Second, the construction of the locking ring beam 1: after the precipitation reaches the design requirements, the locking ring beam foundation pit is excavated and supported, and the vertical shaft locking ring beam 1 and retaining wall are constructed;

[0034] The construction is carried out according to the following steps:

[0035] (a) Ring beam excavation: The lock ring beam 1 is designed as a rectangular cast-in-place concrete structure, which is constructed by open excavation. Mechanical excavation and manual bottom cleaning are used at the ring beam. After digging to the designed ring beam bottom elevation, the bottom of the ring beam and the slope soil surface are cleaned and leveled;

[0036] (b) Binding the ring beam reinforcement 101: Bind the overlapped part of the bottom and top layers of reinforcement, and bind the stirrups there according to the designed spacing to form a basic skeleton; arrange the main reinforcement of the outer ring of the lock ring on both sides, and set steel joints at the places with less stress. The upper and lower joints are staggered by 50%, and the length of the connection section of the joint is 35d; arrange the stirrups on one side of the lock ring beam 1 to the end to avoid the phenomenon of no stirrups;

[0037] (c) Installing the formwork: Clean the formwork before installation and apply a release agent to prevent sticking; the ring beam formwork is assembled with a combination of steel formwork, with tight joints and the outer side of the formwork is firmly secured with square wood;

[0038] (d) Concrete pouring: The ring beam concrete is commercial concrete, which is transported to the site by a transport vehicle, poured into the mold using a chute, and compacted with a vibrator. The first steel grille 202 under the locking ring beam 1 is poured together with the ring beam reinforcement 101;

[0039] (e) Set the ring beam water retaining wall: After the concrete of the lock-in ring beam 1 reaches 70% of the designed strength, build a water retaining wall on the top of the ring beam, and the water retaining wall is 500 mm higher than the natural ground surface.

[0040] Third, shaft excavation and initial support construction: The shaft is excavated from top to bottom using the inverted shaft wall method; the shaft excavation is carried out by the method of sectional and layered excavation and support; first, the soil layer around the shaft is excavated, and then the middle core soil is excavated; during the downward excavation, grouting anchor pipes 201 are driven, and the initial support 2 (including cross braces and corner braces) is constructed; when the shaft is excavated to a position 2 meters below the arch crown of the tunnel, a temporary bottom seal is carried out, and the advanced measures for the construction of the horsehead portal are implemented. Advance large pipe roofs are constructed near the arch of the tunnel 5, and the formation is reinforced by grouting with advance small pipes 203.

[0041] The specific construction steps are as follows:

[0042] (a) Set the shaft: According to the design requirements, select the shaft position and carry out shaft excavation underground; set a wellhead lining at the bottom of the well to support the shaft.

[0043] (b) Installation of the inverted shaft: Lift the prefabricated inverted shaft into the well and make it closely fit with the bottom lining of the well; use special equipment in the industry to fix the shaft on the shaft wall to ensure the firmness and stability of the shaft.

[0044] (c) Excavation and support: The shaft is excavated step by step according to the construction plan, and at the same time, earthwork transportation and treatment are carried out; the shaft wall is supported while excavating; as the shaft is excavated, the subsequent steel grids 202 are installed in sequence, and steel mesh 204 is laid and tied on both the inside and outside sides; then, grouting anchor pipes 201 are circumferentially inclined and set according to the excavation contour line for grouting reinforcement; finally, transverse support structures such as cross braces 205 are installed to enhance the overall stiffness and stability of the support structure; the characteristic of the inverted shaft wall method is to support the shaft wall while excavating to ensure construction safety.

[0045] (d) Shaft wall treatment: After excavating to a certain depth, the shaft wall is treated by spraying concrete to prevent collapse; after excavating to the designed depth, the bottom of the foundation pit is treated, including cleaning and trimming; the support structure 2 is inspected and repaired to ensure the construction quality.

[0046] (e) Manhole cover installation: After waiting for the well lining to completely solidify, install the manhole cover on the top of the shaft to ensure the safety and hygiene of the shaft.

[0047] Fourth, shotcrete: Shotcrete construction shall be carried out in a timely manner after the completion of the steel grid 202, and the actual thickness during construction shall be strictly controlled to avoid being too thick or too thin. The shotcreting operation shall be carried out in slices and sections according to the construction technical plan, starting from the side and then the top, and from bottom to top. During construction, it shall be carried out strictly in accordance with the design and construction specifications. The shotcrete shall be carried out in layers, with each layer having a thickness of 50 - 60 mm. The shotcrete shall use C25 early-strength concrete, which is mixed on-site and adopts the wet shotcreting process. Starting from the bottom of the shaft, it is transported to the working tray on the working surface through the pipes installed on the shaft wall and sprayed layer by layer to evenly cover the entire shaft wall surface. When constructing the shotcrete, the shotcreting machine shall be set at the wellhead. As the shaft is excavated, the shotcreting pipe shall be extended for shotcrete operation. During spraying, the nozzle shall be kept perpendicular to the sprayed surface. When the concrete attached to the rock surface slides and flows, the maximum thickness of a single spray is reached, and spraying shall stop at this time. After the shotcrete begins to set, respraying shall be carried out.

[0048] Fifth, shaft bottom sealing: When the shaft is excavated to the upper bench of the cross-passage, temporary shaft bottom sealing shall be carried out first. The bottom sealing shall use I20a steel beams for paving, and the I20a steel beams shall be connected to the steel grid 202 on the side wall of the shaft body. The I20a steel beams shall be arranged at the designed spacing, and after being connected with a single-layer steel mesh 204, C20 concrete shall be used for pouring the bottom of the shaft. After the shaft is excavated to the bottom, the last frame of the side wall of the shaft body still uses the steel grid, and the four corners of the foundation pit bottom shall be locked with foot-locking anchor pipes. After the foot-locking anchor pipes are arranged, grouting shall be carried out for the anchor pipes. The bottom sealing still uses I20a steel beams for paving, and the I20a steel beams shall be connected to the steel grid on the side wall of the shaft body. The I20a steel beams shall be arranged at the designed spacing, and after being connected with a double-layer steel mesh 204, C25 concrete shall be used for pouring the bottom of the shaft.

[0049] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device.

[0050] The above-described embodiments are only descriptions of the preferred modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solution of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A rectangular shaft construction structure in a water-rich loess layer, characterized by: The invention comprises a locking ring beam (1), the inner side of the locking ring beam (1) is a rectangular shaft area, the inner side of the rectangular shaft area is provided with a supporting structure (2), the inner side of the supporting structure (2) is provided with a reinforced concrete beam slab (3), and prestressed anchor rods (4) are used to anchor the reinforced concrete beam slab and the supporting structure (2) to the surrounding stable soil.

2. The rectangular vertical shaft construction structure in the water-rich loess layer according to claim 1 is characterized by: The support structure (2) comprises a grouting anchor pipe (201), a steel grille (202), an advance small conduit (203), a steel mesh (204) and a cross brace (205); the steel grille (202) is arranged along the inner wall of the rectangular shaft area, and two groups of the steel grilles (202) located on opposite surfaces are connected by the cross brace (205); the steel mesh (204) is laid on both sides of the inner and outer sides of the steel grille (202), and the steel mesh (204) is connected to the steel grille (202) by binding, and concrete is sprayed after the support structure (2) is installed in place; the input ends of the grouting anchor pipe (201) and the advance small conduit (203) are connected to the external grouting pipe, and the output ends of the grouting anchor pipe (201) and the advance small conduit (203) are inserted into the surrounding rock mass.

3. The rectangular vertical shaft construction structure in the water-rich loess layer according to claim 2 is characterized by: The plurality of grouting anchor pipes (201) and the plurality of small advance guide pipes (203) are all arranged in a circular manner according to the excavation contour line and are obliquely inserted into the surrounding rock mass.

4. The rectangular vertical shaft construction structure in the water-rich loess layer according to claim 2 is characterized by: A locking ring beam reinforcement (101) is arranged inside the locking ring beam (1), and the locking ring beam (1) is a cast-in-place rectangular concrete structure.

5. The rectangular vertical shaft construction structure in the water-rich loess layer according to claim 4 is characterized by: The locking ring beam reinforcement (101) is cast simultaneously with the first steel grating (202) located below.

6. The rectangular vertical shaft construction structure in the water-rich loess layer according to claim 4 is characterized by: A water retaining wall is built on the top of the locking ring beam (1), and the water retaining wall is at least 500 mm higher than the natural ground.

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