Hydraulic pressure inclined support combined balance construction method for short curved line vertical excavation of special-shaped foundation pit

Abstract

The present application relates to a water pressure inclined support combined balance construction method for short curved edge vertical excavation of special-shaped foundation pit, a water retaining wall suitable for short curved edge excavation contour is formed by splicing of multiple rectangular water retaining plates, a water tank is formed by the gap between the water retaining wall and the retaining wall, liquid is injected into the water tank, and the water pressure and the inclined support axial force are adjusted in combination, which not only solves the problem of insufficient construction space of ordinary support, but also effectively relieves the uneven stress deformation of the earth wall caused by only one inclined support, and realizes efficient support and construction of the short curved edge area of the special-shaped foundation pit. The rectangular water retaining plate combination is similar in shape to the short curved edge curve, and through the water pressure balance principle, the effects of uneven deformation of the retaining structure and stress concentration of the short curved edge caused by the small number of supports are weakened. The method can be flexibly applied in construction, can effectively balance the soil pressure, and improve the construction safety and efficiency of the short curved edge contour of the special-shaped foundation pit.

Description

Technical Field

[0001] This invention relates to the construction of vertical excavation of foundation pits, specifically to a water pressure bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides. Background Technology

[0002] With the continuous development of urban construction, the demand for irregularly shaped foundation pits with curved edges (hereinafter referred to as "irregular foundation pits") is increasing. Traditionally, vertical excavation of irregular foundation pits often uses inclined bracing to support the retaining structure. For irregular foundation pits with long curved edges (usually referring to cases where the arc length of the edge is greater than 20m), due to the relatively spacious construction space, multiple inclined bracings can be arranged along the long curved edge contour. In existing designs, the spacing between adjacent inclined bracings is generally 20m. Using multiple inclined bracings can share the soil pressure and reduce the stress concentration of the wall.

[0003] However, for the vertical excavation of irregularly shaped foundation pits with short curved edges (mainly referring to cases where the arc length of the edge line is less than 20m), the traditional inclined support method faces a series of challenges. Due to the limited construction space and irregular outline, only a single inclined brace can be set to support the short curved edge retaining structure, resulting in concentrated stress distribution in the wall at the brace support point, which poses certain risks to construction safety. Traditional support methods usually require sectional excavation, and in areas with narrow excavation faces, the erection of the support system becomes complex and inflexible. Due to the limitation of construction space, construction efficiency is also significantly affected, and it may even lead to increased construction difficulty and safety hazards. Summary of the Invention

[0004] This invention proposes a construction method based on the combined balance of hydraulic diagonal bracing for vertical excavation of irregularly shaped foundation pits with short curved sides. This method aims to reduce the uneven deformation and stress concentration of the retaining structure caused by relying solely on a single diagonal brace. Within a limited construction space, it can reduce the axial force of the diagonal brace, increase the applicable engineering range of the diagonal brace, and improve the safety and construction efficiency of vertical excavation of irregularly shaped foundation pits with short curved sides.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The hydraulic bracing combination and balancing construction method for vertical excavation of irregularly shaped foundation pits with short curved sides includes the following steps: Step 1): Based on the parameters of the excavated soil layer of the irregular foundation pit and the inclination angle of the diagonal bracing. i Calculate the average stress value at a single brace support when the enclosure structure adopts the traditional diagonal bracing scheme; Step 2): Set the stress threshold at the diagonal brace support. Compare the average stress value calculated in Step 1) with the stress threshold. If the average stress value is less than the stress threshold, the traditional diagonal brace scheme is adopted; if the average stress value is greater than or equal to the stress threshold, the following steps are performed. Step 3): Prepare multiple water-retaining plates, ensuring that the longitudinal height of each plate is at least the same as the excavation depth of the irregular-shaped foundation pit. Arrange multiple sets of water-retaining plates in pairs along the contour of the curved edge wall of the irregular-shaped foundation pit to form a water-retaining wall. Adjacent water-retaining plates are connected and sealed at the joints. The bottom of the water-retaining plate contacts the bottom of the foundation pit, and the joints are also sealed. A water channel is formed between the water-retaining wall and the curved edge wall. The lateral width of the water-retaining plates does not exceed 5% of the arc length of the curved edge of the irregular-shaped foundation pit. Step 4): Make a through hole on the water-retaining plate of the retaining wall, pass the support of the diagonal brace through the through hole and fix it to the ground wall. Seal the gap between the through hole and the support. Set the diagonal brace according to the preset tilt angle, fix one end of the diagonal brace to the support, and fix the other end of the diagonal brace to the bottom of the foundation pit. Step 5): After completing step 4), inject liquid into the water tank so that the surface of the liquid in the water tank is flush with the top surface of the pit. Step 6): After completing Step 5), calculate the actual average stress value at the inclined support. Compare the actual average stress value with the stress threshold. If the actual average stress value is still greater than or equal to the stress threshold, increase the density of the liquid in the tank and dynamically adjust the actual average stress value at the inclined support until the actual average stress value is less than the stress threshold.

[0006] Furthermore, in step 1), the average stress value at a single diagonal brace support in the case of a traditional diagonal bracing scheme for the enclosure structure is calculated as follows: The weight of the soil in the irregular foundation pit excavation area is known. c internal friction angle f Excavation depth H Inclination angle of the diagonal brace i The area of ​​the support for the diagonal brace on the enclosure structure S 0 Arc length of the curved edge of the irregular foundation pit l ; Calculate the active earth pressure coefficient K a , ; Calculate the resultant force of active earth pressure E a , ; Calculate the axial force of the diagonal brace R a , ; Calculate the average stress of the brace support .

[0007] Furthermore, the water baffle has a rectangular outline.

[0008] Furthermore, the horizontal width of the water baffle is 1m.

[0009] Furthermore, in step 3), adjacent water baffles are connected by hinges and bolts, and the joints are sealed with sealing strips.

[0010] Furthermore, in step 6), the actual average stress at the diagonal brace support is calculated as follows: The weight of the soil in the irregular foundation pit excavation area is known. c internal friction angle f Excavation depth H Inclination angle of the diagonal brace i The area of ​​the support for the diagonal brace on the enclosure structure S 0 Arc length of the curved edge of the irregular foundation pit l The density of the liquid injected into the tank r gravitational acceleration g; Calculate the active earth pressure coefficient K a , ; Calculate the resultant force of active earth pressure E a , ; Calculate the current equilibrium resultant force P , ; Calculate the current axial force of the diagonal brace. R a , ; Calculate the actual average stress of the current diagonal brace support. .

[0011] Furthermore, in step 3), the number of water-retaining plates required to form the water-retaining wall is determined according to the following method: Assume that each water-retaining plate has a rectangular outline and the same dimensions, and that the lateral width of each water-retaining plate is... a Let the radius of the curved side of the irregular foundation pit be... r Let the central angle of the curved arc length of the irregular foundation pit be . p Let the actual distance between the retaining wall and the ground wall be... d The maximum distance between the retaining wall and the ground wall is [value missing]. d max ; (1) Calculate the central angle corresponding to each group of water baffles. α , Take the first calculation d=d max ; (2) Calculate the number of water-blocking plates required. N ,N =2 p / α ; (3) Determine the number of water-blocking plates calculated in step (2) above. N If the result is even, then the calculated result is the actual number of water-blocking boards required; if the result is odd, then continue with the following steps. (4) When reducing the central angle in step (1) above. d The value of is then determined, and the calculation is performed again according to the formulas given in steps (1) and (2) above. d The number of water-blocking plates required after the value is reduced is adjusted until the calculated number of water-blocking plates is an even number, corresponding to the adjusted value. d The value represents the actual distance between the retaining wall and the ground wall during construction.

[0012] This invention innovatively proposes a construction method based on a combination of water-pressure inclined bracing for vertical excavation of irregularly shaped foundation pits with short curved sides. This method not only breaks through the application limitations of traditional single-bracing support systems, but also increases the applicable engineering range of the inclined bracing by reducing the axial force of the bracing, weakens the uneven deformation and stress concentration of the retaining structure, and achieves efficient support for narrow excavation faces. In this invention, the water-retaining plate and the side wall of the foundation pit form a water-filled trough space for injecting liquid. This cleverly utilizes the principle of water pressure balance, improving the distribution of soil pressure from being entirely borne by the inclined bracing to being shared by the inclined bracing and the water pressure in the trough. This expands the stress-bearing area to the entire side of the curved retaining structure of the irregularly shaped foundation pit, thereby increasing the stress-bearing area and making the force distribution more uniform. This solution effectively saves space and balances soil pressure during construction, improving the safety and efficiency of vertical excavation of irregularly shaped foundation pits with short curved sides. Attached Figure Description

[0013] Figure 1 This is a side view of the irregularly shaped foundation pit with water-retaining plates and diagonal braces arranged at the short curved edge, as shown in the embodiment. Figure 2 This is a plan view of the outline of an irregularly shaped foundation pit with short curved edges in one embodiment; Figure 3 This is a schematic diagram showing the connection between two adjacent water baffles; Figure 4 A schematic diagram showing the relevant parameters of the water baffle and the short curved edge profile when calculating the number of water baffles.

[0014] Explanation of icon numbers: 1. Water baffle; 2. Diagonal brace; 3. Support; 4. Water pump; 5. Water pipe; 6. Short curved edge; 7. Hinge; 8. Bolt. Detailed Implementation

[0015] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0016] This embodiment discloses a water-pressure inclined bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides, such as... Figure 2 As shown, the closed structure enclosed by solid lines is an example of an irregularly shaped foundation pit outline. The interior of the closed structure is the area that needs to be excavated vertically. Figure 2 The number 6 in the diagram represents the short curved side of the irregularly shaped foundation pit. Short curved side 6 is arc-shaped, and the solution shown in this embodiment is suitable for situations where the arc length of the short curved side is less than 20m. Due to insufficient construction space, the vertical excavation of the short curved side 6 is only sufficient to install one diagonal brace 2 to support the ground wall. At this time, the soil pressure behind the retaining structure is entirely borne by the diagonal brace 2, and the stress-bearing area is only the area of ​​the support 3 of the diagonal brace 2. This stress concentration can easily lead to uneven deformation of the retaining structure, posing a potential safety hazard during construction.

[0017] For a known vertical excavation of an irregularly shaped foundation pit, this embodiment determines whether the hydraulic bracing combination balance construction scheme provided by this invention is suitable. This assessment is based on the stress state analysis of the curved retaining structure of the irregularly shaped foundation pit. If the bracing force on the retaining structure is too large and concentrated, the construction scheme of this invention is appropriate. Since the stress on the retaining structure is related to soil properties, excavation depth, and other factors, this invention uses the average stress at the support 3 of the bracing 2 as a reference and compares it with a set stress threshold to determine suitability. Combined with... Figure 1 to Figure 3 As shown, the specific construction method of the present invention can be summarized as follows: Step 1): Based on the parameters of the excavated soil layer of the irregular foundation pit and the inclination angle of the diagonal bracing. i Calculate the average stress value at 3 points of a single diagonal brace support when the enclosure structure adopts the traditional diagonal bracing scheme; Step 2): Set the stress threshold at the diagonal brace support 3. Compare the average stress value calculated in Step 1) with the stress threshold. If the average stress value is less than the stress threshold, the traditional diagonal brace scheme is adopted; if the average stress value is greater than or equal to the stress threshold, the following steps are performed. Step 3): Prepare multiple water-retaining plates 1, ensuring that the longitudinal height of each water-retaining plate 1 is at least the same as the excavation depth of the irregular foundation pit. Arrange multiple sets of water-retaining plates 1 along the contour of the curved edge wall of the irregular foundation pit in pairs to form a water-retaining wall. Adjacent water-retaining plates 1 are connected and the joints are sealed. The bottom of the water-retaining plate 1 contacts the bottom of the foundation pit and the joints are sealed. A water trough is formed between the water-retaining wall and the curved edge wall. Step 4): Open a through hole on the water-retaining plate 1 of the retaining wall, pass the support 3 of the diagonal brace 2 through the through hole and fix it to the ground wall, seal the gap between the through hole and the support 3, set the diagonal brace 2 at the preset tilt angle, fix one end of the diagonal brace 2 to the support 3, and fix the other end of the diagonal brace 2 to the bottom of the pit. Step 5): After completing step 4), use the water pipe 5 connected to the water pump 4 to inject liquid into the water tank until the surface of the liquid in the water tank is level with the top surface of the pit. Step 6): After calculating the actual average stress value at the inclined support 3 after completing Step 5), compare the actual average stress value with the stress threshold. If the actual average stress value is still greater than or equal to the stress threshold, increase the density of the liquid in the water tank and dynamically adjust the actual average stress value at the inclined support 3 until the actual average stress value is less than the stress threshold.

[0018] To more clearly illustrate the implementation of the construction scheme of this invention, the following focuses on... Figure 2 The irregular foundation pit outline shown is used as the standard for judging the stress magnitude of the retaining structure with a stress threshold of 20MPa. A specific embodiment is given.

[0019] Example 1: Known soil weight in the irregularly shaped foundation pit excavation area c 20kN / m 3 internal friction angle f 15°, excavation depth H The inclination angle is 20m and the diagonal brace is 2. i The support area of ​​the 30° diagonal brace 2 on the enclosure structure. Arc length of the curved edge of the irregular foundation pit l It is 20m.

[0020] First, assess the stress on the curved enclosure structure when relying solely on a single diagonal brace, following these steps: (1) Calculation of active earth pressure coefficient,

[0021] (2) Calculation of the resultant force of active earth pressure,

[0022] (3) Calculation of axial force of diagonal brace,

[0023] (4) Assess the stress state of the curved enclosure structure. .

[0024] According to the evaluation structure, when supported by only a single diagonal brace 2, the average stress at the diagonal brace support 3 is greater than the stress threshold of 20MPa. This indicates that the diagonal brace support force on the retaining structure is too large and concentrated. The water pressure diagonal brace combination balance construction scheme disclosed in this invention should be adopted to reduce the stress on the diagonal brace support 3.

[0025] In this embodiment, multiple rectangular water-retaining plates 1 are installed along the contour of the curved edge wall of the foundation pit. Two water-retaining plates 1 are arranged vertically in pairs. Adjacent water-retaining plates 1 are connected by hinges 7 and bolts 8, and the gaps between adjacent water-retaining plates 1 are sealed with rubber sealing strips. The integrated water-retaining plates 1 form a water-retaining wall, and a distance is left between the water-retaining wall and the curved edge wall of the foundation pit. d The bottom of the retaining wall is in close contact with the bottom of the foundation pit, and the gaps are filled with sealing hydraulic tape to form a water tank that can be injected with liquid. Liquid (such as water or mud) is injected into the water tank until it is flush with the top surface of the foundation pit, and the water pressure is used to balance the force on the diagonal brace support 3. After the retaining wall is installed, a through hole is made in the retaining plate 1 at the determined position of the fixed diagonal brace 2. The support 3 of the diagonal brace 2 is passed through the through hole and fixed to the ground wall. The gap between the through hole and the support 3 is sealed with waterproof tape, and the gap is filled with micro-expansion concrete to ensure the seal. The diagonal brace 2 is set at a preset inclination angle, with one end of the diagonal brace 2 fixed to the support 3 and the other end of the diagonal brace 2 fixed to the bottom of the foundation pit.

[0026] When designing the water-retaining plate 1, the primary consideration is its material's pressure resistance and waterproofing. The shape of the water-retaining plate 1 is designed to be easily arranged along the curved contour of the foundation pit through multi-segment splicing, achieving versatility and cost savings. Therefore, a rectangular water-retaining plate 1 is used in this embodiment. For the dimensions of the rectangular water-retaining plate 1, with the vertical placement direction as a reference, the longitudinal height of the water-retaining plate 1 should be at least consistent with the excavation depth of the foundation pit. Considering the modular production, assembly-based connection, and reusability of the prefabricated water-retaining plate 1, it is recommended that the longitudinal height of the water-retaining plate 1 be designed as an integer multiple of 5m. The transverse width of the water-retaining plate 1 should not exceed 5% of the arc length of the curved edge of the irregular foundation pit. In this embodiment, a transverse width of 1m is preferred. Narrower water-retaining plates 1 are easier to adapt to and surround the curved contour of the foundation pit, and can also reduce the occupation of internal space in the foundation pit. The thickness of the water-retaining plate 1 is mainly designed for pressure resistance; the thicker the plate, the better the pressure resistance, while a thin plate has poor pressure resistance.

[0027] To form a retaining wall surrounding the curved contour of the foundation pit, the required number of retaining plates 1 needs to be determined. In this embodiment, each retaining plate 1 has the same size and shape, using retaining plates 1 with a longitudinal height of 5m and a transverse width of 1m. Combined with... Figure 4 The annotations of the parameters shown are used to illustrate how to calculate the required number of water baffles 1, taking this embodiment as an example.

[0028] First, assume that the horizontal width of each water-blocking plate 1 is... a =1m, let the radius of the curved side arc of the irregular foundation pit be r =25m, let the central angle of the curved arc length of the irregular foundation pit be . p =90°, let the actual distance between the retaining wall and the ground wall be . d Let the upper limit of the distance between the retaining wall and the ground wall be _____. d max =0.4m.

[0029] Step 1: Estimate the central angle corresponding to each set of water baffles 1 α When calculating the central angle for the first time, let the following formula be used... d=d max :

[0030] Step 2: Estimate the required number of water-blocking plates 1 N :

[0031] Step 3: Determine the number of water-blocking plates calculated in Step 2 above. N If the result is even, then the result calculated in the second step is the actual number of water-retaining plates required. If the result is odd, then the following steps need to be performed (because the water-retaining wall of this invention is formed by arranging two water-retaining plates 1 as a group, so the number of water-retaining plates 1 needs to be even).

[0032] Step 4: Estimate the distance between the retaining wall and the ground wall as assumed in Step 1. d The value is adjusted; in this embodiment, it will be... d The value was reduced from the original upper limit of 0.4m to 0.18m, and then recalculated according to the formulas given in steps one and two above. d The number of water-retaining plates required after reducing the value is continued until the calculated number of water-retaining plates 1 is an even number. This determines the actual distance between the water-retaining wall and the ground wall during final construction. d The value of .

[0033]

[0034]

[0035] From the above calculation results, it can be seen that... dAfter adjusting the value of 0.4m to 0.18m, the number of water-retaining plates 1 obtained by recalculation is 40, which is an even number. Finally, it can be determined that the number of water-retaining plates 1 required to form a water-retaining wall that can surround the curved edge of the foundation pit in this embodiment is 40.

[0036] Whether the combination of diagonal bracing for the retaining wall formed according to the above calculation results and the described method can achieve the purpose of reducing the stress on the retaining structure needs to be verified through the following calculation process. Once the verification is successful, construction can proceed according to this scheme.

[0037] The weight of the soil in the irregular foundation pit excavation area is known. c 20kN / m 3 internal friction angle f 15°, excavation depth H The inclination angle is 20m and the diagonal brace is 2. i The support area of ​​the 30° diagonal brace 2 on the enclosure structure. Arc length of the curved edge of the irregular foundation pit l The density of the liquid injected into the 20m water tank r =1000kg / m 3 Gravitational acceleration g = 9.80 m / s² 2 .

[0038] (1) Calculation of active earth pressure coefficient,

[0039] (2) Calculation of the resultant force of active earth pressure,

[0040] (3) Calculation of equilibrium resultant force,

[0041] (4) Calculation of axial force of diagonal brace, (5) Evaluate the stress state of the curved retaining structure under the combined hydraulic bracing scheme. .

[0042] The comparison of calculation results between the single-bracing and water-pressure bracing combination schemes shows that under the water-pressure bracing combination scheme, the axial force on brace 2 is significantly reduced, and the average stress at brace support 3 is also reduced to less than the stress threshold of 20MPa. This indicates that the improved construction method of this invention applies water pressure to the entire curved surface of the retaining structure, which can significantly reduce the bracing support force on the retaining structure, making the overall stress distribution more uniform and greatly improving the safety of construction.

[0043] If the average stress value at the inclined support calculated after verification is still greater than the stress threshold, the liquid density in the injection tank can be dynamically increased. rAfter adjusting the liquid density, repeat the above calculation process to verify the stress on the curved retaining structure until the calculated average stress value at the inclined brace support is lower than the stress threshold. Once the verification results are satisfactory, construction can proceed according to the determined parameters.

[0044] This invention, through the splicing of rectangular water-retaining plates 1, can adapt to the contours of different curved edges of foundation pits, and the water-retaining plates 1 can be recycled. The water trough space formed by the water-retaining plates 1 and the side of the foundation pit can apply water pressure to the side of the foundation pit after water is stored, balancing part of the soil pressure. According to the principle of force balance, the axial force required to maintain the balance of the excavation face is also reduced accordingly, and the deformation is relatively uniform.

[0045] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A water-pressure bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides, characterized in that... Includes the following steps: Step 1): Based on the parameters of the excavated soil layer of the irregular foundation pit and the inclination angle of the diagonal bracing. θ Calculate the average stress value at a single brace support when the enclosure structure adopts the traditional diagonal bracing scheme; Step 2): Set the stress threshold at the diagonal brace support. Compare the average stress value calculated in Step 1) with the stress threshold. If the average stress value is less than the stress threshold, the traditional diagonal brace scheme is adopted. If the average stress value is greater than or equal to the stress threshold, then perform the following steps; Step 3): Prepare multiple water-retaining plates, ensuring that the longitudinal height of each plate is at least the same as the excavation depth of the irregular-shaped foundation pit. Arrange multiple sets of water-retaining plates in pairs along the contour of the curved edge wall of the irregular-shaped foundation pit to form a water-retaining wall. Adjacent water-retaining plates should be connected and sealed at the joints. The bottom of the water-retaining plate should contact the bottom of the foundation pit, and the joints should also be sealed. A water channel should be formed between the water-retaining wall and the curved edge wall. The lateral width of the water-retaining plates should not exceed 5% of the arc length of the curved edge of the irregular-shaped foundation pit. Step 4): Make a through hole on the water-retaining plate of the retaining wall, pass the support of the diagonal brace through the through hole and fix it to the ground wall. Seal the gap between the through hole and the support. Set the diagonal brace according to the preset tilt angle, fix one end of the diagonal brace to the support, and fix the other end of the diagonal brace to the bottom of the foundation pit. Step 5): After completing step 4), inject liquid into the water tank so that the surface of the liquid in the water tank is flush with the top surface of the pit. Step 6): After completing Step 5), calculate the actual average stress value at the inclined support. Compare the actual average stress value with the stress threshold. If the actual average stress value is still greater than or equal to the stress threshold, increase the density of the liquid in the tank and dynamically adjust the actual average stress value at the inclined support until the actual average stress value is less than the stress threshold.

2. The water pressure bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides as described in claim 1, characterized in that: In step 1), the average stress value at a single diagonal brace support in the case of a traditional diagonal bracing scheme for the enclosure structure is calculated as follows: The weight of the soil in the irregular foundation pit excavation area is known. γ internal friction angle φ Excavation depth H Inclination angle of the diagonal brace θ The area of ​​the support for the diagonal brace on the enclosure structure S 0 Arc length of the curved edge of the irregular foundation pit l ; Calculate the active earth pressure coefficient K a , ; Calculate the resultant force of active earth pressure E a , ; Calculate the axial force of the diagonal brace R a , ; Calculate the average stress of the brace support .

3. The water pressure bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides according to claim 1, characterized in that: The water baffle has a rectangular outline.

4. The water pressure bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides according to claim 1, characterized in that: The horizontal width of the water baffle is 1m.

5. The water pressure bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides according to claim 1, characterized in that: In step 3), adjacent water baffles are connected by hinges and bolts, and the joints are sealed with sealing strips.

6. The water pressure diagonal bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides according to claim 1, characterized in that: In step 6), the actual average stress at the diagonal brace support is calculated as follows: The weight of the soil in the irregular foundation pit excavation area is known. γ internal friction angle φ Excavation depth H Inclination angle of the diagonal brace θ The area of ​​the support for the diagonal brace on the enclosure structure S 0 Arc length of the curved edge of the irregular foundation pit l The density of the liquid injected into the tank ρ gravitational acceleration g; Calculate the active earth pressure coefficient K a , ; Calculate the resultant force of active earth pressure E a , ; Calculate the current equilibrium resultant force P , ; Calculate the current axial force of the diagonal brace. R a , ; Calculate the actual average stress of the current diagonal brace support. .

7. The water pressure bracing combined with balanced construction method for vertical excavation of irregularly shaped foundation pits with short curved sides according to claim 1, characterized in that: In step 3), the number of water-retaining plates required to form the water-retaining wall is determined as follows: Assume that each water-retaining plate has a rectangular outline and the same dimensions, and that the lateral width of each water-retaining plate is... a Let the radius of the curved side of the irregular foundation pit be... r Let the central angle of the curved arc length of the irregular foundation pit be . p Let the actual distance between the retaining wall and the ground wall be... d The maximum distance between the retaining wall and the ground wall is [value missing]. d max ; (1) Calculate the central angle corresponding to each group of water baffles. α , Take the first calculation d=d max ; (2) Calculate the number of water-blocking plates required. N , N =2 p / α ; (3) Determine the number of water-blocking plates calculated in step (2) above. N If the result is even, then the calculated result is the actual number of water-blocking boards required; if the result is odd, then continue with the following steps. (4) When reducing the central angle in step (1) above. d The value of is then determined, and the calculation is performed again according to the formulas given in steps (1) and (2) above. d The number of water-blocking plates required after the value is reduced is adjusted until the calculated number of water-blocking plates is an even number, corresponding to the adjusted value. d The value represents the actual distance between the retaining wall and the ground wall during construction.

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