Method and device for determining anti-overturning coefficient of pit-in-pit double-row pile supporting structure

Abstract

The application discloses a method and device for determining an anti-overturning coefficient of a pit-in-pit double-row-pile supporting structure, and relates to the technical field of foundation pit engineering. The method comprises the following steps: determining a trapezoidal cross-section earth covering rupture angle and an earth covering rupture surface of a trapezoidal cross-section earth covering between a pit-in-pit structure and a double-row-pile supporting structure according to an internal friction angle of soil; determining an anti-sliding force of soil above the earth covering rupture surface according to the size of the trapezoidal cross-section earth covering between the pit-in-pit structure and the double-row-pile supporting structure, the trapezoidal cross-section earth covering rupture angle and the shear strength of the soil layer; and determining the anti-overturning coefficient according to the anti-sliding force of the soil above the earth covering rupture surface, the earth pressure outside and inside the foundation pit, the distance between the anti-sliding force action point and the bottom of the double-row-pile supporting structure and the self-weight of the double-row-pile and the soil between the piles. The method solves the problem that the embedded depth of the supporting structure is generally designed according to experience and is too conservative in the prior art, and the embedded depth of the supporting structure is too deep, which greatly increases the construction cost.

Description

Technical Field

[0001] This invention relates to the field of foundation pit engineering technology, specifically to a method and device for determining the overturning resistance coefficient of a double-row pile support structure within a pit. Background Technology

[0002] In building construction, transportation engineering, and water conservancy engineering, foundation pit support is a very common sub-project, and the overturning resistance coefficient of the support structure is one of the many parameters controlling the stability of foundation pit projects. With the increasing complexity of structures, the phenomenon of pits within pits is becoming more and more common in foundation pit engineering, making the assessment of the overturning resistance of support structures under pit-within-pit conditions increasingly important.

[0003] In existing technologies, when designing the overturning resistance of support structures under pit-in-pit conditions, the embedment depth of the support structure is generally designed too conservatively based on experience, resulting in the support structure being embedded too deeply, which significantly increases construction costs. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a method and apparatus for determining the overturning coefficient of a double-row pile support structure in a pit-within-a-pit system. This method solves the problem that the embedment depth of the support structure in existing technologies is generally designed too conservatively based on experience, resulting in excessively deep embedment of the support structure and significantly increased construction costs.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] On the one hand, this solution provides a method for determining the overturning resistance coefficient of a double-row pile support structure within a pit, including:

[0007] Based on the internal friction angle of the soil, determine the trapezoidal cross-section soil rupture angle and soil rupture surface between the pit-in-pit and the double-row pile support structure.

[0008] Based on the dimensions of the trapezoidal cross-section of the overburden between the pit-in-pit and the double-row pile support structure, the rupture angle of the trapezoidal cross-section of the overburden, and the shear strength of the soil layer, the anti-sliding force of the soil above the rupture surface of the overburden is determined.

[0009] The overturning resistance coefficient is determined based on the soil resistance above the rupture surface, the soil pressure inside and outside the pit, the distance between the point of action of the resistance force and the bottom of the double-row pile support structure, and the self-weight of the double-row piles and the soil between the piles.

[0010] In some alternative solutions, determining the anti-sliding force of the soil above the overburden fracture surface based on the dimensions of the trapezoidal cross-section overburden between the pit-in-pit and the double-row pile support structure, the rupture angle of the trapezoidal cross-section overburden, and the shear strength of the soil layer includes:

[0011] The weight of the soil above the rupture surface is determined based on the size of the trapezoidal cross-section of the overburden between the pit-in-pit and the double-row pile support structure and the rupture angle of the trapezoidal cross-section overburden.

[0012] The anti-sliding force of the soil above the rupture surface is determined based on the weight of the soil above the rupture surface and the shear strength of the soil layer.

[0013] In some alternative solutions, according to the formula:

[0014] Determine the weight of the soil above the ruptured surface;

[0015] Where W1 is the weight of the soil above the rupture surface, γ is the soil weight, a is the top width of the trapezoidal cross-section overburden, b is the bottom width of the trapezoidal cross-section overburden, h is the height of the trapezoidal cross-section overburden, and α is the angle between the bottom edge of the trapezoidal cross-section overburden and the side furthest from the double-row pile support structure, α= θ is the soil rupture angle of the trapezoidal cross section. The friction angle within the soil.

[0016] In some alternative solutions, according to the formula:

[0017] Determine the sliding resistance of the soil above the rupture surface of the overburden;

[0018] Where R is the anti-sliding force of the soil above the rupture surface, W1 is the weight of the soil above the rupture surface, and θ is the rupture angle of the trapezoidal cross-section. denoted as the internal friction angle of the soil, c as the shear strength of the soil layer, b as the width of the bottom of the trapezoidal cross-section overburden, and α as the angle between the bottom edge of the trapezoidal cross-section overburden and the side furthest from the double-row pile support structure.

[0019] In some alternative solutions, according to the formula: Determine the overturning resistance coefficient;

[0020] Among them, K e E is the overturning resistance coefficient. pk For the passive earth pressure inside the foundation pit, a p R is the distance from the point of application of passive earth pressure on the inner side of the foundation pit to the bottom of the double-row pile support structure; R is the anti-sliding force of the soil above the rupture surface of the overburden; and θ is the rupture angle of the overburden in the trapezoidal section. Let L be the internal friction angle of the soil. d E is the distance from the point of application of the anti-sliding force of the soil above the rupture surface to the bottom of the double-row pile support structure. ak For the active earth pressure outside the foundation pit, a a G is the distance from the point of application of the active earth pressure inside the foundation pit to the bottom of the double-row pile support structure, and G is the self-weight of the double-row piles and the soil between the piles. g It is the horizontal distance from the center of gravity of the double-row piles and the soil between the piles to one side of the double-row pile foundation pit.

[0021] In some optional solutions, before determining the anti-sliding force of the soil mass above the failure surface of the covering soil based on the dimensions of the trapezoidal-section covering soil between the inner pit and the double-row pile support structure, the failure angle of the trapezoidal-section covering soil and the shear strength of the soil layer, it is judged whether to consider the influence of the inner pit structure on the anti-overturning performance of the double-row pile support structure according to the dimensions of the trapezoidal-section covering soil in the inner pit and the failure angle of the trapezoidal-section covering soil.

[0022] In some optional solutions, when the formula: a < h / tanθ is satisfied, the influence of the inner pit structure on the anti-overturning performance of the double-row pile support structure is considered;

[0023] wherein, a is the top width of the trapezoidal-section covering soil, h is the height of the trapezoidal-section covering soil, θ is the failure angle of the trapezoidal-section covering soil, is the internal friction angle of the soil mass.

[0024] In some optional solutions, after determining the anti-overturning coefficient, it is judged whether the double-row pile support structure meets the anti-overturning requirement according to the design grade of the foundation pit.

[0025] In some optional solutions, the anti-overturning requirement is as follows: the anti-overturning coefficient of a grade I foundation pit is greater than 1.25, the anti-overturning coefficient of a grade II foundation pit is greater than 1.2, and the anti-overturning coefficient of a grade III foundation pit is greater than 1.15.

[0026] In another aspect, the present solution also provides an anti-overturning coefficient determination device for a double-row pile support structure of an inner pit, comprising:

[0027] a covering soil failure surface determination module, which is configured to determine the failure angle of the trapezoidal-section covering soil and the covering soil failure surface of the trapezoidal-section covering soil between the inner pit and the double-row pile support structure according to the internal friction angle of the soil mass;

[0028] a soil anti-sliding force determination module, which is configured to determine the anti-sliding force of the soil mass above the covering soil failure surface according to the dimensions of the trapezoidal-section covering soil between the inner pit and the double-row pile support structure, the failure angle of the trapezoidal-section covering soil and the shear strength of the soil layer;

[0029] an anti-overturning coefficient determination module, which is configured to determine the anti-overturning coefficient according to the anti-sliding force of the soil mass above the covering soil failure surface, the earth pressure inside and outside the foundation pit, the distance between the action point of the anti-sliding force and the bottom of the double-row pile support structure and the dead weight of the double-row piles and the soil between the piles.

[0030] Compared with existing technologies, the advantages of this invention are as follows: This solution determines the trapezoidal cross-section overburden rupture angle and rupture surface of the overburden between the pit-in-pit and the double-row pile support structure based on the internal friction angle of the soil; it determines the anti-sliding force of the soil above the rupture surface based on the dimensions of the trapezoidal cross-section overburden between the pit-in-pit and the double-row pile support structure, the rupture angle of the trapezoidal cross-section overburden, and the shear strength of the soil layer; and it determines the overturning resistance coefficient based on the anti-sliding force of the soil above the rupture surface, the earth pressure inside and outside the pit, the distance between the point of application of the anti-sliding force and the bottom of the double-row pile support structure, and the self-weight of the double-row piles and the soil between the piles. This solves the problem in existing technologies where the embedment depth of the support structure is generally designed too conservatively based on experience, resulting in excessively deep embedment of the support structure and a significant increase in construction costs. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the double-row pile support structure in the pit within the pit in an embodiment of the present invention;

[0033] Figure 2 This is a flowchart illustrating the method for determining the overturning resistance coefficient of a double-row pile support structure within a pit, as described in an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0035] The embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0036] like Figure 1 As shown, the double-row pile support structure includes two parallel, spaced-apart retaining piles extending into the soil, with one retaining pile positioned along the sidewall of the foundation pit. Soil lies between the two retaining piles, and the tops of the piles are capped by steel connecting beams. The side of the double-row pile support structure away from the foundation pit sidewall has a trapezoidal cross-section of overburden, forming a pit-within-a-pit on the side of the trapezoidal cross-section overburden away from the double-row pile support structure.

[0037] like Figure 2As shown, in one aspect, the present invention provides a method for determining the anti-overturning coefficient of a double-row pile support structure for a pit-in-pit, comprising:

[0038] S1: According to the internal friction angle of the soil mass, determine the fracture angle and fracture surface of the trapezoidal section overburden between the pit-in-pit and the double-row pile support structure.

[0039] In this embodiment, the fracture angle of the trapezoidal section overburden is Figure 1 angle DEF therein.

[0040] S20: According to the size of the trapezoidal section overburden in the pit-in-pit and the fracture angle of the trapezoidal section overburden, determine whether to consider the influence of the pit-in-pit structure on the anti-overturning performance of the double-row pile support structure.

[0041] In some alternative embodiments, when the formula is satisfied: a < h / tanθ, the influence of the pit-in-pit structure on the anti-overturning performance of the double-row pile support structure is considered;

[0042] Wherein, a is the top width of the trapezoidal section overburden, h is the height of the trapezoidal section overburden, θ is the fracture angle of the trapezoidal section overburden, is the internal friction angle of the soil mass.

[0043] S2: According to the size of the trapezoidal section overburden between the pit-in-pit and the double-row pile support structure, the fracture angle of the trapezoidal section overburden, and the shear strength of the soil layer, determine the anti-sliding force of the soil mass above the overburden fracture surface.

[0044] Step S2 specifically comprises:

[0045] S21: According to the size of the trapezoidal section overburden between the pit-in-pit and the double-row pile support structure and the fracture angle of the trapezoidal section overburden, determine the gravity of the soil mass above the overburden fracture surface.

[0046] In some alternative embodiments, according to the formula:

[0047] determine the gravity of the soil mass above the overburden fracture surface;

[0048] Wherein, W1 is the gravity of the soil mass above the overburden fracture surface, γ is the unit weight of the soil mass, a is the top width of the trapezoidal section overburden, b is the bottom width of the trapezoidal section overburden, h is the height of the trapezoidal section overburden, α is the included angle between the bottom edge of the trapezoidal section overburden and the side away from the double-row pile support structure, α= θ is the fracture angle of the trapezoidal section overburden, is the internal friction angle of the soil mass.

[0049] S22: According to the gravity of the soil mass above the overburden fracture surface and the shear strength of the soil layer, determine the anti-sliding force of the soil mass above the overburden fracture surface.

[0050] In some alternative embodiments, according to the formula:

[0051] Determine the sliding resistance of the soil above the rupture surface of the overburden;

[0052] Where R is the anti-sliding force of the soil above the rupture surface, W1 is the weight of the soil above the rupture surface, and θ is the rupture angle of the trapezoidal cross-section. denoted as the internal friction angle of the soil, c as the shear strength of the soil layer, b as the width of the bottom of the trapezoidal cross-section overburden, and α as the angle between the bottom edge of the trapezoidal cross-section overburden and the side furthest from the double-row pile support structure.

[0053] S3: Determine the overturning resistance coefficient based on the soil resistance above the rupture surface, the soil pressure inside and outside the foundation pit, the distance between the point of action of the resistance force and the bottom of the double-row pile support structure, and the self-weight of the double-row piles and the soil between the piles.

[0054] In some alternative embodiments, according to the formula: Determine the overturning resistance coefficient;

[0055] Among them, K e E is the overturning resistance coefficient. pk For the passive earth pressure inside the foundation pit, a p R is the distance from the point of application of passive earth pressure on the inner side of the foundation pit to the bottom of the double-row pile support structure; R is the anti-sliding force of the soil above the rupture surface of the overburden; and θ is the rupture angle of the overburden in the trapezoidal section. Let L be the internal friction angle of the soil. d E is the distance from the point of application of the anti-sliding force of the soil above the rupture surface to the bottom of the double-row pile support structure. ak For the active earth pressure outside the foundation pit, a a G is the distance from the point of application of the active earth pressure inside the foundation pit to the bottom of the double-row pile support structure, and G is the self-weight of the double-row piles and the soil between the piles. g It is the horizontal distance from the center of gravity of the double-row piles and the soil between the piles to one side of the double-row pile foundation pit.

[0056] In some alternative embodiments, after determining the overturning resistance coefficient, the double-row pile support structure is judged to meet the overturning resistance requirements based on the foundation pit design level.

[0057] In some optional embodiments, the overturning resistance requirements are: the overturning resistance coefficient for a first-level foundation pit is greater than 1.25, the overturning resistance coefficient for a second-level foundation pit is greater than 1.2, and the overturning resistance coefficient for a third-level foundation pit is greater than 1.15.

[0058] In this embodiment, the foundation pit setting level is determined according to the actual project requirements.

[0059] On the other hand, the present invention also provides a device for determining the overturning coefficient of a pit-within-a-pit double-row pile support structure, comprising:

[0060] The overburden rupture surface determination module is used to determine the trapezoidal section overburden rupture angle and overburden rupture surface of the overburden between the pit-in-pit and the double-row pile support structure based on the internal friction angle of the soil.

[0061] The soil anti-sliding force determination module is used to determine the soil anti-sliding force above the overburden fracture surface based on the size of the trapezoidal cross-section overburden between the pit-in-pit and the double-row pile support structure, the trapezoidal cross-section overburden fracture angle, and the soil shear strength.

[0062] The overturning resistance coefficient determination module is used to determine the overturning resistance coefficient based on the soil resistance above the overburden rupture surface, the soil pressure inside and outside the foundation pit, the distance between the point of application of the resistance force and the bottom of the double-row pile support structure, and the self-weight of the double-row piles and the soil between the piles.

[0063] In summary, this invention determines the trapezoidal section rupture angle and rupture surface of the overburden between the pit-in-pit and the double-row pile support structure based on the internal friction angle of the soil. It also determines the anti-sliding force of the soil above the rupture surface based on the dimensions of the trapezoidal section overburden between the pit-in-pit and the double-row pile support structure, the rupture angle of the trapezoidal section overburden, and the shear strength of the soil layer. Furthermore, it determines the overturning resistance coefficient based on the anti-sliding force of the soil above the rupture surface, the earth pressure inside and outside the pit, the distance between the point of application of the anti-sliding force and the bottom of the double-row pile support structure, and the self-weight of the double-row piles and the soil between the piles. This provides guidance for the embedment depth of the support structure in subsequent designs. This solves the problem in existing technologies where the embedment depth of the support structure is generally designed too conservatively based on experience, leading to excessively deep embedment and significantly increased construction costs.

[0064] This invention modifies the conventional overturning resistance calculation method for double-row pile support structures, and effectively proposes a method for calculating the overturning stability of double-row pile support structures in the case of pit-within-pit situations where the soil inside the pit influences the double-row pile support structure. It optimizes the embedment depth of the double-row pile support structure, avoiding excessive embedment and improving economic efficiency.

[0065] The following specific examples will help to facilitate understanding of the present invention.

[0066] For a certain foundation pit project, the pit depth H = 8m, the 20m below ground level is a silty clay layer, there is no groundwater, the shear strength of the soil layer is c = 22kPa, and the internal friction angle of the soil is... The soil weight is γ = 18.5 kN / m. The uniformly distributed load at the top of the pit is considered to be q = 20 kPa. The pit support structure adopts a double-row pile support structure with a pile diameter of 0.8 m, a pile spacing of 2.6 m, a center-to-center distance of 1.0 m for the front row piles, and a center-to-center distance of 2.0 m for the rear row piles. The embedment depth of the retaining piles is Ld = 5 m. The pit safety level is Level 1. The top width of the trapezoidal cross-section overburden is measured as a = 2 m, the bottom width as b = 5 m, and the height as h = 3 m. The rupture angle of the trapezoidal cross-section overburden is... The self-weight of the double-row piles and the soil between them, G = 881.411 kN / m. The horizontal distance a from the center of gravity of the double-row piles and the soil between them to one side of the double-row pile foundation pit. g =1.7m.

[0067] Active earth pressure coefficient

[0068] Critical depth of soil

[0069] Active earth pressure outside the foundation pit

[0070] Distance from the point of application of active earth pressure on the inner side of the foundation pit to the bottom of the double-row pile support structure

[0071] passive earth pressure coefficient

[0072] passive earth pressure on the inside of the foundation pit

[0073] The distance a from the point of application of passive earth pressure on the inner side of the foundation pit to the bottom of the cantilever support structure p1 =L d / 3 = 5 / 3 = 1.667m.

[0074] Since a = 2m < 3 / tan38.5° = 3.772m, the influence of the pit-within-a-pit structure on the overturning resistance of the cantilever support structure is considered.

[0075] Weight of soil above the rupture surface

[0076] Sliding resistance of soil above the rupture surface

[0077] Overturning resistance coefficient It meets the requirement that the overturning resistance coefficient of a Class I foundation pit is greater than 1.25.

[0078] In the description of this application, it should be noted that the terms "upper," "lower," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. Unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication between two elements. For those skilled in the art, the specific meaning of the above terms in this application can be understood according to the specific circumstances.

[0079] It should be noted that in this application, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0080] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for determining the overturning resistance coefficient of a double-row pile support structure within a pit, characterized in that, include: Based on the internal friction angle of the soil, determine the trapezoidal cross-section soil rupture angle and soil rupture surface between the pit-in-pit and the double-row pile support structure. Based on the dimensions of the trapezoidal cross-section of the overburden between the pit-in-pit and the double-row pile support structure, the rupture angle of the trapezoidal cross-section of the overburden, and the shear strength of the soil layer, the anti-sliding force of the soil above the rupture surface of the overburden is determined. The overturning resistance coefficient is determined based on the soil resistance above the rupture surface, the soil pressure inside and outside the pit, the distance between the point of action of the resistance force and the bottom of the double-row pile support structure, and the self-weight of the double-row piles and the soil between the piles. The determination of the anti-sliding force of the soil above the rupture surface of the overburden, based on the dimensions of the trapezoidal cross-section of the overburden between the pit-in-pit and the double-row pile support structure, the rupture angle of the trapezoidal cross-section of the overburden, and the shear strength of the soil layer, includes: The weight of the soil above the rupture surface is determined based on the size of the trapezoidal cross-section of the overburden between the pit-in-pit and the double-row pile support structure and the rupture angle of the trapezoidal cross-section overburden. The anti-sliding force of the soil above the rupture surface of the overburden is determined based on the weight of the soil above the rupture surface and the shear strength of the soil layer. According to the formula: Determine the overturning resistance coefficient; in, The overturning resistance coefficient, For the passive earth pressure inside the foundation pit, This is the distance from the point of application of passive earth pressure on the inner side of the foundation pit to the bottom of the double-row pile support structure. The sliding resistance of the soil above the rupture surface. For trapezoidal cross-section, the soil rupture angle is... , The internal friction angle of the soil. It is the distance from the point of application of the anti-sliding force of the soil above the rupture surface to the bottom of the double-row pile support structure. This refers to the active earth pressure outside the foundation pit. This is the distance from the point of application of the active earth pressure on the inner side of the foundation pit to the bottom of the double-row pile support structure. The weight of the double-row piles and the soil between the piles is the self-weight. It is the horizontal distance from the center of gravity of the double-row piles and the soil between the piles to one side of the double-row pile foundation pit.

2. The method for determining the overturning resistance coefficient of a double-row pile support structure within a pit as described in claim 1, characterized in that, According to the formula: Determine the weight of the soil above the ruptured surface; in, The weight of the soil above the fracture surface is the weight of the soil. Soil weight, The width of the top of the trapezoidal cross-section cover soil. The width of the bottom of the trapezoidal cross-section cover soil. The soil cover height is the height of the trapezoidal cross section. The angle between the bottom edge of the trapezoidal cross-section covered by soil and the side furthest from the double-row pile support structure. , For trapezoidal cross-section, the soil rupture angle is... , The friction angle within the soil.

3. The method for determining the overturning resistance coefficient of a double-row pile support structure within a pit as described in claim 1, characterized in that, According to the formula: Determine the anti-sliding force of the soil above the rupture surface of the overburden; in, The sliding resistance of the soil above the rupture surface. The weight of the soil above the fracture surface is the weight of the soil. For trapezoidal cross-section, the soil rupture angle is... , The internal friction angle of the soil. For soil shear strength, The width of the bottom of the trapezoidal cross-section cover soil. The angle between the bottom edge of the trapezoidal cross-section covered by soil and the side furthest from the double-row pile support structure. .

4. The method for determining the overturning resistance coefficient of a double-row pile support structure within a pit as described in claim 1, characterized in that, Before determining the anti-sliding force of the soil above the rupture surface of the overburden based on the size of the trapezoidal section of the overburden between the pit-in-pit and the double-row pile support structure, the influence of the pit-in-pit structure on the overturning resistance of the double-row pile support structure should be considered based on the size of the trapezoidal section of the overburden within the pit and the rupture angle of the trapezoidal section of the overburden.

5. The method for determining the overturning resistance coefficient of a double-row pile support structure within a pit as described in claim 1, characterized in that, When the formula is satisfied: When considering the impact of the pit-within-a-pit structure on the overturning resistance of the double-row pile support structure; in, The width of the top of the trapezoidal cross-section cover soil. The soil cover height is the height of the trapezoidal cross section. For trapezoidal cross-section, the soil rupture angle is... , The friction angle within the soil.

6. The method for determining the overturning resistance coefficient of a double-row pile support structure within a pit as described in claim 1, characterized in that, After determining the overturning resistance coefficient, based on the foundation pit design level, determine whether the double-row pile support structure meets the overturning resistance requirements.

7. The method for determining the overturning resistance coefficient of a double-row pile support structure within a pit as described in claim 6, characterized in that, The overturning resistance requirements are as follows: the overturning resistance coefficient for Class I foundation pits is greater than 1.25, the overturning resistance coefficient for Class II foundation pits is greater than 1.2, and the overturning resistance coefficient for Class III foundation pits is greater than 1.

15.

8. A device for determining the overturning coefficient of a pit-within-a-pit double-row pile support structure, characterized in that, in order to implement the overturning coefficient determination method as described in any one of claims 1-7, include: The overburden rupture surface determination module is used to determine the trapezoidal section overburden rupture angle and overburden rupture surface of the overburden between the pit-in-pit and the double-row pile support structure based on the internal friction angle of the soil. The soil anti-sliding force determination module is used to determine the soil anti-sliding force above the overburden fracture surface based on the size of the trapezoidal cross-section overburden between the pit-in-pit and the double-row pile support structure, the trapezoidal cross-section overburden fracture angle, and the soil shear strength. The overturning resistance coefficient determination module is used to determine the overturning resistance coefficient based on the soil resistance above the overburden rupture surface, the soil pressure inside and outside the foundation pit, the distance between the point of application of the resistance force and the bottom of the double-row pile support structure, and the self-weight of the double-row piles and the soil between the piles.

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