A diaphragm wall type shaft construction method

Abstract

This invention relates to the field of shaft construction technology, and particularly to a diaphragm wall type shaft construction method, comprising the following steps: S1: constructing a guide wall, the guide wall forming a polygon; S2: constructing a diaphragm wall along the guide wall, the diaphragm wall forming a polygonal enclosure structure; S3: constructing high-pressure jet grouting piles within the diaphragm wall for bottom sealing; S4: excavating the shaft pit within the diaphragm wall, and setting waist beams layer by layer, the waist beams being connected to the diaphragm wall until the pit bottom slab is completed. The diaphragm wall and high-pressure jet grouting piles together form a three-dimensional water-stopping system, solving the problems of weak water-stopping and seepage prevention capabilities of traditional processes. During pit excavation, waist beams are set layer by layer, and the waist beams are connected to the diaphragm wall. The waist beams and the diaphragm wall form a closed ring support system, dispersing and transferring soil loads layer by layer, controlling lateral deformation of the pit, and reducing construction disturbance to surrounding buildings and underground pipelines.

Description

Technical Field

[0001] This invention relates to the field of shaft construction technology, and in particular to a diaphragm wall type shaft construction method. Background Technology

[0002] In urban water supply pipeline projects, temporary shafts are often excavated for the lowering of tunnel boring machines and pipeline launch. The stability of the shaft support and the reliability of water sealing directly affect construction safety. Traditional shafts often use bored piles and sheet piles for support. These methods result in poor overall structural integrity, weak connections between walls, and a tendency for joint leakage. In areas with high groundwater levels or soft soil, the water sealing effect is prone to failure, leading to sidewall seepage and foundation heave. Furthermore, traditional support systems lack sufficient rigidity and have weak deformation control capabilities, making them susceptible to significant lateral displacement, which can affect the safety of surrounding buildings and underground pipelines. Summary of the Invention

[0003] The purpose of this invention is to provide a diaphragm wall type vertical shaft construction method to address the problems existing in the background art.

[0004] This invention provides a method for constructing a diaphragm wall type vertical shaft, comprising the following steps:

[0005] S1: Construction guide wall, which forms a polygon; S2: Construct a diaphragm wall along the guide wall, the diaphragm wall forming a polygonal enclosure structure; S3: High-pressure jet grouting piles are installed inside the diaphragm wall for bottom sealing. S4: Excavate the foundation pit of the vertical shaft within the diaphragm wall, and install waist beams layer by layer. The waist beams are connected to the diaphragm wall until the foundation pit bottom slab is completed.

[0006] Preferably, in step S2, a trench is excavated between the guide walls. During the trenching process, a skip-trenching method is used. After excavating one section of the trench, the diaphragm wall for that section is constructed, and then the next section of the trench is excavated and constructed, ensuring the stability of the trench and the continuity of construction.

[0007] Preferably, in step S2, the trench is divided into an even number of standard segments, and two symmetrical standard segments form a group; Each of the standard segments includes a pre-groove segment and a post-groove segment. Between adjacent standard segments, the pre-groove segment of one standard segment is connected to the post-groove segment of another standard segment to achieve a tight engagement between the standard segments.

[0008] Preferably, step S2 includes the following steps: S21: Excavate the pre-excavation section of each group of standard sections in sequence. After the pre-excavation section is completed, carry out the diaphragm wall construction of this section, and then excavate the pre-excavation section of the next group of standard sections until all the pre-excavation sections are completed. S22: Then, the back trench of each group of standard sections is excavated in sequence. After the back trench is excavated, the diaphragm wall of this section is constructed. Then, the back trench of the next group of standard sections is excavated until all the back trenches are constructed to form a continuous diaphragm wall.

[0009] Preferably, the excavated trench section is brushed to remove impurities and ensure the quality of the diaphragm wall.

[0010] Preferably, a reinforcing cage is installed in the completed trench section, and underwater concrete pouring is used to construct the diaphragm wall.

[0011] Preferably, in S4, the cap beam is constructed first, and then the foundation pit is excavated. The foundation pit is excavated in layers according to the number of waist beams. The waist beam is constructed each time the excavation reaches the bottom elevation of the waist beam. Excavate to the designed elevation at the bottom of the foundation pit and pour a foundation layer to construct the foundation slab. Strictly control the risk of foundation pit deformation.

[0012] Preferably, the first layer of earthwork is excavated to the design elevation at the bottom of the capping beam, the pile heads of the high-pressure jet grouting piles are broken, and the capping beam is constructed. After the strength of the cap beam reaches the design requirements, subsequent earthwork excavation and pile head removal will be carried out. Each layer of earthwork will be excavated to the design elevation of the bottom of the waist beam, and the waist beam construction will be carried out. After the strength of the wainscoting reaches the design requirements, the lower layer of earthwork is completed, and the above steps are repeated until the excavation reaches the design elevation of the bottom of the foundation pit. Then, the bottom slab of the foundation pit is constructed.

[0013] Preferably, in S4, before the foundation pit is excavated, a dewatering well is set inside the diaphragm wall. The dewatering well is equipped with a concrete filter pipe, and a filter material filling layer is set between the concrete filter pipe and the wall of the dewatering well. A water pump is also placed at the bottom of the dewatering well. Furthermore, the bottom of the drainage well is located below the excavation surface of the foundation pit, and is used to drain the moisture from the soil in the foundation pit.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The diaphragm wall shaft construction method of this invention first constructs a polygonal guide wall to locate the outline area of ​​the shaft. Then, a diaphragm wall is constructed along the guide wall, forming a polygonal enclosure structure to effectively support and reinforce the soil, resist lateral soil pressure during excavation, and simultaneously achieve lateral waterproofing of the pit. Next, high-pressure jet grouting piles are added inside the diaphragm wall to reinforce and seal the base of the pit, achieving base water stoppage and anti-piping. The diaphragm wall and high-pressure jet grouting piles together form a three-dimensional water-stopping system, solving the problems of weak seepage prevention and single water-stopping in traditional methods. This effectively addresses complex conditions such as high groundwater levels and soft soil strata, preventing sidewall seepage and base heave. Furthermore, during pit excavation, a waist beam is installed layer by layer, connected to the diaphragm wall. The waist beam and the diaphragm wall form a closed ring support system, dispersing and transferring soil load layer by layer, controlling lateral deformation of the pit, and reducing construction disturbance to surrounding buildings and underground pipelines. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the diaphragm wall type vertical shaft of the present invention.

[0016] Figure 2 This is a top view of a diaphragm wall shaft.

[0017] Figure 3 This is a schematic diagram of the guide wall.

[0018] Figure 4 This is a schematic diagram of the trench segmentation of the diaphragm wall.

[0019] Figure 5 This is a schematic diagram of the foundation pit excavation.

[0020] Figure 6 This is a schematic diagram of a drainage well.

[0021] Marked in the image: 1-Guide Wall 2-Diameter wall, 3-High-pressure jet grouting piles, 4-Foundation pit, 5-Waist beam, 6-Cover beam, 7-Trench, 71-Standard section, 711-Pre-trench section, 712-Rear-trench section 8-Drainage well, 9-Concrete filter pipe, 10-Filter media packing, 20-Water Pump, 30 - Drainage pipe. Detailed Implementation

[0022] The present invention will now be described in further detail with reference to specific embodiments. However, this should not be construed as limiting the scope of the present invention to the following embodiments; all technologies implemented based on the content of the present invention fall within the scope of the present invention.

[0023] Unless otherwise specified, the use of terms such as "upper," "lower," "left," "right," "center," "inner," and "outer" to indicate orientation or positional relationships in the description of specific embodiments of the present invention is based on the orientation or positional relationships shown in the accompanying drawings, or the orientation or positional relationship in which the product / equipment / device is typically placed during use. These terms are merely for the purpose of facilitating the description of the present invention or simplifying the description in specific embodiments, enabling those skilled in the art to quickly understand the solution, and do not indicate or imply that a particular device / component / element must have a specific orientation, or be constructed and operated in a specific positional relationship. Therefore, they should not be construed as limitations on the present invention.

[0024] Furthermore, the use of terms such as "horizontal," "vertical," "suspended," "parallel," and "coaxial" does not imply that the corresponding device / component / element must be absolutely horizontal, vertical, suspended, parallel, or coaxial. Slight tilt or deviation is permissible, as long as it does not affect the normal function of the relevant component. For example, "horizontal" simply means that its direction is more horizontal relative to "vertical," not that the structure must be perfectly horizontal; a slight tilt is acceptable. "Coaxial" means that two components are set as coaxially as possible, allowing them to move coaxially or approximately coaxially when their relative positions change. Alternatively, it can be simplified to mean that the corresponding device / component / element, when set in a "horizontal," "vertical," "suspended," "parallel," or "coaxial" direction, can have an error / deviation of ±10% relative to the corresponding direction, more preferably within ±8%, more preferably within ±6%, more preferably within ±5%, and more preferably within ±4%. For example, the deviation in the "coaxial" direction is controlled within 0.2-1mm, preferably within 0.2-0.5mm. As long as the corresponding device / component / element is within the error / deviation range, it can still achieve its function in the solution of the present invention.

[0025] Furthermore, the use of terms such as "first," "second," and "third" in terminology is merely for distinguishing descriptions of identical or similar components and should not be interpreted as emphasizing or implying the relative importance of a particular component.

[0026] Furthermore, in the description of the embodiments of the present invention, "several", "more than", and "a number of" represent at least two. The number can be any number, such as 2, 3, 4, 5, 6, 7, 8, or 9, and can even exceed nine.

[0027] Furthermore, in the description of the technical solution of this invention, unless otherwise explicitly specified / limited / restricted, the terms "set up," "install," "connect," "link," "provided with," "laid out," and "arranged" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to common connection methods in the art, such as welding, riveting, bolting, and threaded connections. Such connections can be mechanical, electrical, or communication connections; they can be direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components.

[0028] Example 1 like Figures 1-5 As shown, a construction method for a diaphragm wall type vertical shaft includes the following steps: S1: Construction guide wall 1, guide wall 1 forms a polygon; S2: Construct diaphragm wall 2 along guide wall 1, and diaphragm wall 2 encloses a polygonal enclosure structure; S3: Inside the diaphragm wall 2, high-pressure jet grouting piles are used for bottom sealing. S4: Excavate the foundation pit 4 of the vertical shaft inside the diaphragm wall 2, and install the waist beam 5 layer by layer. The waist beam 5 is connected to the diaphragm wall 2 until the foundation pit bottom slab is completed.

[0029] The diaphragm wall shaft construction method of this embodiment first constructs a polygonal guide wall 1 to locate the outline area of ​​the shaft. Then, a diaphragm wall 2 is constructed along the guide wall 1. The diaphragm wall 2 forms a polygonal enclosure structure, which makes the overall rigidity of the diaphragm wall 2 stronger and can distribute the soil pressure to effectively support and reinforce the soil and resist the lateral soil pressure during the excavation of the foundation pit 4. At the same time, it achieves side waterproofing of the foundation pit 4. Then, high-pressure jet grouting piles 3 are constructed in the diaphragm wall 2 to reinforce and seal the bottom of the foundation pit 4, so as to achieve water stop and anti-piping of the foundation. The diaphragm wall 2 and the high-pressure jet grouting piles 3 together form a three-dimensional water stop system, which solves the problems of single water stop and weak seepage prevention capacity of traditional technology. It effectively copes with complex working conditions such as high groundwater and soft soil strata, and effectively copes with problems such as side wall seepage and foundation heave. Furthermore, when the foundation pit 4 is excavated, the waist beams 5 are set layer by layer. The waist beams 5 are connected to the diaphragm wall 2. The waist beams 5 and the diaphragm wall 2 form a closed ring support system, which disperses and transfers the soil load layer by layer, controls the lateral deformation of the foundation pit, and reduces the construction disturbance to the surrounding buildings and underground pipelines.

[0030] In this embodiment, the bottom of the diaphragm wall 2 is located below the designed elevation of the bottom surface of the foundation pit 4. The diaphragm wall 2 serves as the support structure of the foundation pit 4 and also as a side water-stop curtain. The bottom of the high-pressure jet grouting pile 3 is located below the designed elevation of the bottom surface of the foundation pit 4. The retaining structure adopts the diaphragm wall 2 as the support structure and also as a water-stop curtain. The total depth of the wall is 29.1m, of which the anchoring depth below the excavation surface is 11.9m (insertion ratio 0.69). A reinforced concrete cap beam 6 is set on the top of the wall, and three ring-shaped reinforced concrete waist beams 5 are set in the middle. The waist beams 5 and the diaphragm wall 2 form an integral ring support system. The high-pressure jet grouting pile 3 and the diaphragm wall 2 together constitute a double-layer water-stop.

[0031] The specific steps are as follows: S1: Construction guide wall 1, guide wall 1 forms a polygon; Among them, the guide wall 1 adopts a cast-in-place reinforced concrete structure. The guide wall 1 is in the form of "I". The concrete is C30. The guide wall is 1.5m deep and 0.3m thick. The outer side is provided with a flange and the construction road are poured together. S2: Construct diaphragm wall 2 along guide wall 1, forming a polygonal enclosure structure, such as... Figure 3 , Figure 4 As shown, First, based on the design drawings, the dimensions of the groove section are further verified, and the segment marking lines of the diaphragm wall 2 are accurately located on the guide wall 1. Then, the trench excavation is carried out. The trench is formed by first the two sides and then the middle. The first trench segment 711 is constructed first, followed by the second trench segment 712. During the trenching process, skip-trenching excavation and mud slurry wall protection are used. During construction, the adjacent trench segment can only be excavated after the concrete of each underground continuous wall has solidified to the standard. Includes the following: In S2, a trench 7 is excavated between the guide walls 1. During the trenching process, a skip-trenching method is used. After a section of trench 7 is excavated, the diaphragm wall 2 for this section is constructed, and then the next section of trench 7 is excavated and constructed. The trench 7 of the diaphragm wall 2 adopts a construction process of skip-excavation and segmented forming, which avoids the problems of long exposure time of the stratum, soil stress concentration and easy collapse of the trench wall caused by the overall excavation of a large area of ​​trench 7. Furthermore, the segmented excavation and segmented forming operation method can immediately form support and closure for the excavated trench, effectively ensuring the quality of the trench and the stability of the trench wall, and reducing the disturbance of the stratum. At the same time, it can ensure the compactness of the diaphragm wall pouring segment by segment, avoid wall forming defects caused by large-scale construction, and ensure the continuity and integrity of the overall retaining structure. In S2, the groove 7 is divided into an even number of standard segments 71, and two symmetrical standard segments 71 are grouped together, such as... Figure 4 As shown, Each standard segment 71 includes a first slot segment 711 and a second slot segment 712. Between adjacent standard segments 71, the first slot segment 711 of one standard segment 71 is connected to the second slot segment 712 of another standard segment 71. The trench 7 is divided into an even number of standard sections 71, and two symmetrical standard sections 71 are grouped together. The symmetrical grouping excavation method is adopted to avoid the uneven soil pressure on the side of the trench 7 caused by continuous excavation, which could lead to deformation, collapse and other safety risks of the pressure guide wall 1. S2 includes the following steps: S21: Excavate the first trench 711 of each standard section 71 in sequence. After the first trench 711 is excavated, the diaphragm wall 2 of this section is constructed. Then excavate the first trench 711 of the next standard section 71 until all the first trench 711 are constructed. S22: Then excavate the back trench 712 of each standard section 71 in sequence. After the back trench 712 is excavated, the diaphragm wall 2 of this section is constructed. Then excavate the back trench 712 of the next standard section 71 until all back trenches 712 are constructed to form a continuous diaphragm wall 2.

[0032] The first trench 711 of each standard section 71 is excavated sequentially until all first trench 711 are completed. Then, the second trench 712 of each standard section 71 is excavated sequentially until all second trench 712 are completed, forming a continuous diaphragm wall 2. The first trench 711 is constructed uniformly, and the second trench is subsequently closed and formed. The first trench 711 is formed first to build a preliminary overall retaining frame, stabilize the stress of the surrounding strata, and reduce the risk of strata disturbance during subsequent construction. The second trench 712 connects each first trench 711 to achieve seamless interlocking and overall closure of the trenches, ensuring that the diaphragm wall 2 is continuous, dense, and has no leakage channels.

[0033] In an optional implementation, when excavating trenches with a grab bucket, the most crucial point is to ensure the trench is vertical, and to achieve this, the grab bucket must dig under conditions of balanced soil resistance. Either both sides of the grab bucket's teeth should be engaged in the solid soil, or both sides should be positioned within the voids. It is essential to avoid having one side of the grab bucket's teeth engaged in the solid soil while the other side is positioned within a void. Based on this principle, the excavation sequence for each unit trench segment is as follows: When excavating a single trench segment, first excavate the single holes at both ends of the trench segment, or excavate the first hole, skip a certain distance, and then excavate the second hole. This leaves an unexcavated partition wall between the two single holes, which can make the grab bucket exert force evenly when excavating single holes, effectively correct deviation, and ensure the verticality of the trench. First, excavate the single hole, then excavate the partition wall. Because the length of the partition wall is less than the opening length of the grab bucket, the grab bucket can be fitted onto the partition wall for excavation, which also ensures that the grab bucket bears a balanced load, effectively corrects deviation, and guarantees the verticality of the trench.

[0034] Excavate along the length of the trench: After the single holes and the partition walls have been excavated to the designed depth or the rock strata, excavate several buckets along the length of the trench to smooth out the uneven surfaces caused by the different verticality of the trenches formed by the grab buckets when excavating the single holes and partition walls, and ensure that the trench section has good straightness in the transverse direction.

[0035] In an optional implementation, after excavation of a single trench segment, the segment is inspected according to the following standards: The centerline of the trench section should be parallel to the centerline of the designed wall. Based on the construction verticality error and wall deformation requirements, the centerline of the trench section should be appropriately extended by 20cm, and the hole position deviation should be less than 1cm.

[0036] The groove thickness must be greater than the wall's design thickness. A steel frame with a length and width of 1.2 times the wall thickness and a thickness of one wall thickness is used to check whether the wall has equal width.

[0037] The wall surface of the trench is scanned at two positions on the left and right sides within the trench section using an ultrasonic wall measuring instrument. The ratio of the maximum protrusion or indentation of the wall surface (with the guide wall surface as the scanning reference plane) to the depth of the trench section is the wall verticality. The average value of the two positions is the average verticality of the trench wall.

[0038] The hole depth is measured precisely using a special measuring rope, providing reliable data for hole cleaning acceptance and calculation of project quantities.

[0039] In an optional implementation, the excavated trench sections are brushed. Since a layer of mud or slurry often adheres to the old joints during trench wall construction, affecting the quality of adjacent trench wall joints and causing water leakage at the joints, brushing is performed on the excavated first trench section 711 and the second trench section 712. This brushing process thoroughly removes impurities such as silt, sediment, and loose soil from the joints between the trench sections, ensuring a tight fit between the first and second trench sections after pouring. This improves the quality of the joint between the first trench section 711 and the subsequently poured second trench section 712, preventing joint leakage and weak structural connections caused by residual impurities.

[0040] In an optional embodiment, a steel cage is installed in the trench section and underwater concrete is poured to form a diaphragm wall 2 after pouring. Underwater concrete pouring is suitable for construction environments with high groundwater levels, ensuring the density of the concrete wall. The formed diaphragm wall has both high-strength support performance and excellent self-water-stopping performance.

[0041] For underwater concrete pouring, two φ300mm guide pipes are used. The distance between the guide pipes and the end of the trench section should not exceed 1.5m, and the center distance between the two guide pipes should not exceed 3m. The guide pipes should be 0.5m from the bottom of the trench. An airtightness test must be performed on the guide pipes before use to prevent them from bursting and leaking during concrete pouring. The concrete surface rising speed should not be less than 2m / h, the height difference of the concrete surface in the trench should be less than 0.5m, the pause time should be less than 30min, and the burial depth of the guide pipe should be controlled between 2 and 6 meters to prevent pile breakage.

[0042] S3: Inside the diaphragm wall 2, high-pressure jet grouting piles 3 are installed for bottom sealing. Among them, the foundation reinforcement of pit 4 adopts the double-tube high-pressure jet grouting pile technology, with high-pressure jet grouting piles arranged throughout the pit, and the reinforcement depth is 12m below the design bottom plate of pit 4; the grouting uses PO 42.5 ordinary Portland cement with a cement content of 30%, a water-cement ratio of 1:1, a cement grout pressure of 25MPa, and an air pressure of 0.7MPa.

[0043] The total station was used to set out the control piles. Then, a steel tape measure and twine were used to mark the positions of the high-pressure jet grouting piles according to the pile spacing. Small bamboo sticks were used to mark the positions, and white lime was sprinkled to ensure that the pile driver was accurately positioned. After the drilling rig is in place, it is leveled and centered, and its verticality is adjusted to ensure that the drill rod is aligned with the pile position with a deviation of less than 50mm and the verticality error of the borehole is less than 1.0%. Before drilling, the air compressor and mud pump should be tested to ensure that the equipment is operating normally. The length of the drill rod is checked, and the depth line is marked next to the drilling tower with red paint to ensure that the bottom elevation of the hole meets the design depth. After aligning the drill tip with the pile position, start the drill rod and begin drilling. When the ammeter load is stable, lower the drill rod and continue drilling downwards. If the geological conditions are relatively easy to drill through, you can drill to the bottom of the hole in one go. If the geological conditions are difficult to drill through, you can lift the drill rod, clean the mud off the drill rod, and start drilling again. When starting drilling again, the drill tip opening door needs to be cleaned, adjusted, and sealed again. Before the pile driver is moved, the cement grout is prepared according to the design mix ratio. For high-pressure jet grouting piles, the cement grout mix is ​​strictly controlled according to the design requirements, with a water-cement ratio of 1.0. When mixing the grout, water is first added to the bucket, then cement is poured in, and the mixer is started and stirred for 10-20 minutes. The grout must be continuously stirred in the grout mixer until just before spraying. During spraying, the valve at the bottom of the mixing bucket is opened, and the first sieve is placed in. After filtration, the grout flows into the grout pool, and then the grout is pumped through a mud pump into a second sieve (0.8mm aperture). After the second filtration, the grout flows into the grout tank. When the jet grouting pipe is raised close to the top of the pile, it should start from 1.0m below the top of the pile, slowly raise the jet grouting pipe, spray for a few seconds, and then slowly raise it up 0.5m until the grouting surface stops at the top of the pile. After the spraying operation is completed, the grouting pipes and other equipment should be thoroughly rinsed with clean water to prevent solidification and blockage. No cement slurry should remain inside the pipes or equipment. Pour an appropriate amount of clean water into the slurry tank, turn on the high-pressure pump, and clean all remaining cement slurry from the pipelines until they are basically clean. Also, clean any soil adhering to the spraying pipe head.

[0044] S4: Excavate the foundation pit 4 of the vertical shaft within the diaphragm wall 2, and install the lintel beams 5 layer by layer, connecting the lintel beams 5 to the diaphragm wall 2, until the foundation pit bottom slab is completed. Figure 5 As shown.

[0045] In S4, the cap beam 6 is constructed first, and then the foundation pit 4 is excavated. The foundation pit 4 is excavated in layers according to the number of waist beams 5. The waist beam 5 is constructed each time the excavation reaches the bottom elevation of the waist beam 5. Excavate to the design elevation at the bottom of foundation pit 4 and pour the cushion layer to carry out the construction of the bottom slab of foundation pit 4.

[0046] The construction process involves first constructing the cap beam 6, then carrying out the subsequent layered excavation of the foundation pit 4, followed by layer-by-layer wainscoting support, and finally sealing the bottom slab in a closed loop. The foundation pit 4 is excavated using the open excavation method. The first layer of soil is excavated to the bottom design elevation of the capping beam 6. The pile heads of the high-pressure jet grouting piles 3 are broken off, and the capping beam 6 is constructed. After the strength of the cap beam 6 reaches the design requirements, the subsequent earthwork excavation and pile head removal will be carried out. Each layer of earthwork will be excavated to the bottom design elevation of the waist beam 5, and the waist beam 5 will be constructed. After the strength of the wainscoting 5 reaches the design requirements, the lower layer of earthwork is completed. The above steps are repeated until the excavation reaches the design elevation of the bottom of the foundation pit 4. Then, the bottom slab of the foundation pit 4 is constructed.

[0047] The construction method of breaking down pile heads layer by layer and constructing waist beams 5 layer by layer enables the cap beam 6, multiple ring waist beams 5 and diaphragm wall 2 to form a cohesive support system.

[0048] Preferably, the waist beam 5 is connected to the diaphragm wall 2 by means of rebar installation, with the rebar extending into the diaphragm wall by more than 300mm.

[0049] Preferably, the bottom slab of the foundation pit 4 is 800mm thick, the top layer is reinforced with two-way steel bars in a square grid arrangement; the bottom layer is reinforced with two-way steel bars in a square grid arrangement in the middle, the outer side is reinforced with main bars radially pointing towards the center, and the distribution bars are arranged circumferentially, and connected to the diaphragm wall 2 by rebar anchoring. A drainage pipe 30 is installed at the bottom of the foundation pit 4 for temporary drainage before the foundation slab is constructed, and then sealed after the foundation slab is constructed.

[0050] In an optional implementation, in S4, before the excavation of the foundation pit 4, a dewatering well 8 is installed inside the diaphragm wall 2. The dewatering well 8 contains a concrete filter pipe 9, and a filter material filling layer 10 is installed between the concrete filter pipe 9 and the well wall. A water pump 20 is also placed at the bottom of the dewatering well 8. Figure 6 As shown, Furthermore, the bottom of the drainage well 8 is located below the excavation surface of the foundation pit 4.

[0051] Water is pumped from the drainage well 8 by water pump 20 to drain the soil in the foundation pit 4, thereby reducing the impact of groundwater on the foundation pit construction.

[0052] Specifically, a dewatering well 8 is set up in the foundation pit 4 to dewater the soil in the pit. The dewatering well 8 is drilled using a reverse circulation drilling rig, and a sand-free concrete filter pipe is inserted. The outside of the filter pipe is filled with gravel filter material, and the depth of the well is controlled to be 3m below the excavation surface of the foundation pit 4.

[0053] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for constructing a diaphragm wall type vertical shaft, characterized in that, Includes the following steps: S1: Construction guide wall (1), the guide wall (1) forms a polygon; S2: Construct a diaphragm wall (2) along the guide wall (1), and the diaphragm wall (2) forms a polygonal enclosure structure; S3: Inside the diaphragm wall (2), high-pressure jet grouting piles (3) are constructed for bottom sealing. S4: Excavate the foundation pit (4) of the vertical shaft inside the diaphragm wall (2), and install waist beams (5) layer by layer. The waist beams (5) are connected to the diaphragm wall (2) until the foundation pit bottom plate is completed.

2. The construction method for a diaphragm wall type vertical shaft according to claim 1, characterized in that, In S2, a trench (7) is excavated between the guide walls (1). During the trenching process, a skip-trench excavation is adopted. After a section of the trench (7) is excavated, the diaphragm wall (2) of this section is constructed, and then the next section of the trench (7) is excavated and constructed.

3. The construction method for a diaphragm wall type vertical shaft according to claim 2, characterized in that, In S2, the groove (7) is divided into an even number of standard segments (71), and two symmetrical standard segments (71) are grouped together; Each of the standard segments (71) includes a pre-groove segment (711) and a post-groove segment (712), and between adjacent standard segments (71), the pre-groove segment (711) of one standard segment (71) is connected to the post-groove segment (712) of the other standard segment (71).

4. The construction method for a diaphragm wall type vertical shaft according to claim 3, characterized in that, The S2 process includes the following steps: S21: Excavate the pre-excavation section (711) of each group of standard sections (71) in sequence. After the excavation of the pre-excavation section (711) is completed, construct the diaphragm wall (2) of this section. Then excavate the pre-excavation section (711) of the next group of standard sections (71) until all the pre-excavation sections (711) are completed. S22: Then excavate the back trench section (712) of each group of standard sections (71) in sequence. After the back trench section (712) is excavated, the diaphragm wall (2) of this section is constructed. Then excavate the back trench section (712) of the next group of standard sections (71) until all the back trench sections (712) are constructed to form a continuous diaphragm wall (2).

5. The construction method for a diaphragm wall type vertical shaft according to claim 4, characterized in that, The excavated trench sections are then brushed.

6. The construction method for a diaphragm wall type vertical shaft according to claim 5, characterized in that, A steel cage is installed in the completed trench section and underwater concrete is poured to form the diaphragm wall (2).

7. The construction method for a diaphragm wall type vertical shaft according to claim 1, characterized in that, In S4, the cap beam (6) is constructed first, and then the foundation pit (4) is excavated. The foundation pit (4) is excavated in layers according to the number of the waist beams (5). The waist beam (5) is constructed each time the excavation reaches the bottom elevation of the waist beam (5). Excavate to the bottom of the foundation pit (4) at the designed elevation and pour the cushion layer to carry out the bottom slab construction of the foundation pit (4).

8. The method for constructing a diaphragm wall type vertical shaft according to claim 7, characterized in that, The foundation pit (4) is excavated using the open excavation method. The first layer of soil is excavated to the bottom design elevation of the capping beam (6). The pile heads of the high-pressure jet grouting piles (3) are broken off, and the capping beam (6) is constructed. After the strength of the crown beam (6) reaches the design requirements, subsequent earthwork excavation and pile head removal are carried out. Each layer of earthwork is excavated to the design elevation of the bottom of the waist beam (5) and the waist beam (5) is constructed. After the strength of the waist beam (5) reaches the design requirements, the lower layer of earthwork is completed. The above steps are repeated until the excavation reaches the design elevation of the bottom of the foundation pit (4). Then the bottom slab construction of the foundation pit (4) is carried out.

9. A method for constructing a diaphragm wall type vertical shaft according to claim 8, characterized in that, In S4, before the excavation of the foundation pit (4), a drainage well (8) is set in the diaphragm wall (2). A concrete filter pipe (9) is installed inside the drainage well (8). A filter material filling layer (10) is set between the concrete filter pipe (9) and the well wall of the drainage well (8). A water pump (20) is also placed at the bottom of the drainage well (8). Furthermore, the bottom of the drainage well (8) is located below the excavation surface of the foundation pit (4).

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