Large-diameter sparse pile supporting structure and structural calculation method thereof

Abstract

The invention discloses a large-diameter sparse pile supporting structure. Comprising a plurality of arch-shaped units arranged along the edge of a foundation pit, a horizontal top plate arranged at the tops of the arch-shaped units and connecting the arch-shaped units, a hardened face arranged on the side face, away from the foundation pit, of the horizontal top plate, and an intercepting ditch arranged on one side of the hardened face. The protection face is tightly attached to the arch-shaped unit and vertically distributed close to the inner side of the foundation pit; the drainage ditch is arranged at the bottom of the outer side face of the protection face; each arch-shaped unit comprises A-shaped piles, B-shaped piles and grouting holes; the A-shaped piles are located at the two end points of the arch string areas of the arch units, and the adjacent arch units share the A-shaped piles at the connecting positions. The B-type piles are located at the vertexes of the unit arches; the grouting holes comprise a first grouting hole, a second grouting hole and a third grouting hole which are formed in a unit arch string area; the structure rigidity is large, the stability is good, construction is convenient, a barrier-free in-pit operation space is provided, and the construction period is greatly shortened; and the advantages of greenness, low carbon and high efficiency are achieved.

Description

Technical Field

[0001] The invention relates to the field of geotechnical engineering, and in particular to a large-diameter sparse pile supporting method for foundation pit engineering. Background Art

[0002] The arch structure is a curved structure that mainly bears axial pressure and maintains balance by thrust at both ends. Due to its small internal force, it can save consumables and span a larger space. The unsupported support technology is to set up a vertical enclosure structure outside the foundation pit, or add other support measures to stabilize the foundation pit, without setting up a large number of horizontal and vertical support systems in the foundation pit. This technology can save a lot of reinforced concrete materials, and at the same time greatly shorten the construction period of the foundation pit. It has the advantages of low carbon, economy, and high efficiency, and has promotion value.

[0003] In foundation pit projects with a depth of 6 to 10 meters, the commonly used unsupported support technologies include pile-anchor support and double-row pile support. The center distance between the pile rows is generally not more than 2 times the diameter of the pile. The dense rows of piles are high in cost and carbon emissions. How to break through this limitation is a difficult problem in the development of unsupported support technology. Summary of the invention

[0004] The present invention aims to solve the problems of high cost and large carbon emission faced by densely distributed pile rows.

[0005] In order to achieve the above-mentioned purpose, the present invention relates to a large-diameter sparse pile support structure, comprising a plurality of arch units arranged along the edge of a foundation pit, a horizontal top plate arranged on the top of the arch units and connecting the arch units, a hardened surface arranged on the side of the horizontal top plate away from the foundation pit, a drainage ditch arranged on one side of the hardened surface, a protective surface vertically distributed close to the inner side of the arch unit facing the foundation pit, and a drainage ditch arranged at the bottom of the outer side of the protective surface;

[0006] The arch unit includes A-type piles, B-type piles and grouting holes; the A-type piles, B-type piles and grouting holes are all arranged vertically; the A-type piles are distributed at equal intervals near the edge of the foundation pit, and the A-type piles are located in the arch chord area of ​​the arch unit (i.e. Figure 1 The two end points of the area indicated by the dotted line are A-type piles at the joints shared by adjacent arch units; the B-type piles are located at the apex of the unit arch; and the grouting holes include a first grouting hole, a second grouting hole and a third grouting hole arranged in the unit arch chord area.

[0007] Furthermore, the first grouting hole and the second grouting hole are located at 1 / 4 and 3 / 4 of the unit arch chord; and the third grouting hole is located at the midpoint of adjacent A-type piles.

[0008] Furthermore, the hardened surface, intercepting ditch and drainage ditch are all arranged horizontally; the hardened surface and protective surface are waterproof protective surfaces; the intercepting ditch and drainage ditch are drainage networks; and they are used to maintain the engineering properties of the soil.

[0009] Furthermore, the diameter of the A-type pile is greater than that of the B-type pile, ranging from 1.0 to 1.5 meters, and the center distance between two adjacent A-type piles is greater than 1.5D. A +D B To make full use of the pile performance and improve economic efficiency, the center distance between two adjacent A-type piles (1.1) is less than or equal to 2.0D A +DB, prevents shear damage of soil between piles and forms soil arch to effectively support soil between piles. A is the diameter of type A pile, D B is the diameter of the B-type pile; the resistance of the A-type pile is greater than 1.2 times the resultant earth pressure borne by the arch unit.

[0010] Furthermore, the diameter of the B-type pile is smaller than that of the A-type pile, and is 0.6 to 0.8 meters. The B-type pile is located at the highest point of the arch between two adjacent A-type piles (1.1) within the height range of the soil arch, and forms a soil arch with the A-type pile (1.1) to bear the force as a whole. The vertical distance H from the B-type pile to the midpoint of the two adjacent A-type piles is -0.5 (D A -D B )~0.5D A ; The length of the B-type pile is L h +4~L A ,L h is the depth of foundation pit, L A is the length of type A pile; D A is the diameter of type A pile, D B is the diameter of the B-type pile; the lower end of the pile is buried in the hard soil layer and high-pressure grouting is carried out.

[0011] Furthermore, the grouting hole is formed by the grouting pipe and the cement slurry solidified with the in-situ soil; the section inertia moment I of the arch unit is π(0.0156D A 4 +0.0156D B 4 +0.25H 2 D B 2 );D A is the diameter of type A pile, D B is the diameter of the B-type pile. The arch unit is subjected to force as a whole, and can still effectively support the soil outside the foundation pit under the premise of increasing the spacing between the A-type piles. The section inertia moment of the arch unit is much greater than the sum of the section inertia moments of each pile.

[0012] Furthermore, the front edge of the top plate width exceeds the outside diameter of the A-type pile, and the rear edge exceeds the outside diameter of the B-type pile; the top plate height is 0.6 to 0.8D A ;D A is the diameter of the A-type pile; the top plate is connected to the components of the arch unit through anchoring.

[0013] As another aspect of the present invention, it also relates to a structural calculation method of a large-diameter sparse pile support structure, comprising the following steps:

[0014] Step 1: Determine the lateral earth pressure coefficient K based on the horizontal strip distribution ci And calculate the lateral earth pressure strength q ai and lateral earth pressure E ai ;

[0015] Step 2: Determine the soil reaction strength q in front of the pile using the elastic resistance method pi and the soil reaction force in front of the pile P pi ;

[0016] Step 3: Check the embedding stability and calculate the embedding depth l d and type A pile (1.1) pile length L;

[0017] Step 4: Calculate the internal force of the pile and design the structure based on the maximum shear force and maximum bending moment of the pile.

[0018] The method of step 1 is specifically as follows: the principal stress of the soil strip on the potential sliding surface is deflected, σ1 is the maximum principal stress, σ3 is the minimum principal stress, σ v is the vertical stress, σ h is the horizontal stress, K ai is the active earth pressure coefficient of the i-th soil layer, γ i is the soil density of the i-th layer, z i is the burial depth of the midpoint of the i-th soil strip, c i is the cohesion of the i-th soil layer, is the internal friction angle of the i-th soil layer, h is the excavation depth of the foundation pit, θ i is the deformation of the support structure at the calculation point of the i-th layer, a pn is the force arm of the nth layer of soil strip to the pile bottom, a pi is the force arm of the resultant reaction force of the i-th layer of soil on the pile bottom, a ai is the force arm of the active earth pressure on the pile bottom, z n is the burial depth of the midpoint of the nth layer of soil strip;

[0019] Maximum principal stress and rotation angle β i The relationship is:

[0020] because

[0021] Lateral earth pressure coefficient

[0022] Lateral earth pressure strength q ai =K ci γ i z i ;

[0023] Lateral earth pressure

[0024] The method of step 2 is specifically as follows:

[0025] Horizontal resistance coefficient of soil strip Soil reaction strength before pile q pi =K mi ·v i +γ i (z i -h)K ai ;

[0026] Resultant soil reaction force in front of pile

[0027] Furthermore, the specific method of step 3 is:

[0028] Embedded stability verification of arched elements Embedment depth l d =a pn +z n -h;

[0029] Type A pile (1.1) Pile length L = l d +h.

[0030] Furthermore, the specific method of step 4 is:

[0031] When pi =q ai When the maximum shear force of the pile is Q max =∑E ai -∑P pi ;

[0032] When ∑E ai =∑P pi When the maximum bending moment of the pile body is max =∑P pi a pi -∑E ai a ai ;

[0033] Thereby determining the diameter and spacing of the A-type piles.

[0034] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:

[0035] (1) The large-diameter sparse pile support structure of the present invention increases the spacing between the larger-diameter A-type piles by setting a B-type pile at the arch vertex between two adjacent A-type piles in the arch unit. The B-type pile is smaller in diameter and shorter in length than the A-type pile. The top plate, the A-type piles, the B-type piles, and the soil in the enclosed range form an arch structure. The arch structure has high rigidity, good stability, convenient construction, and high efficiency. The number of A-type piles and consumables of B-type piles are reduced while ensuring high bending resistance, providing an unobstructed working space in the foundation pit. While ensuring the stability of the foundation pit, the cost, construction period, and carbon emissions are reduced at the same time, so that the construction period is greatly shortened; the beneficial effects of green, low-carbon, and high efficiency are achieved.

[0036] (2) The large-diameter sparse pile support structure of the present invention has low material consumption, good economy, and is green and low-carbon through optimized calculation and structural design. It improves the problem of high material consumption of dense pile rows, reduces costs and carbon emissions, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0038] Figure 1 is a plan view of a large-diameter sparse pile support structure in an embodiment of the present invention;

[0039] Figure 2 It is a cross-sectional view of a large-diameter sparse pile support structure in an embodiment of the present invention.

[0040] Figure 3 It is a schematic diagram of a grouting hole of a large-diameter sparse pile support structure in an embodiment of the present invention.

[0041] Figure 4 Schematic diagram of the vertical distance H from the midpoint of the B-type pile to the A-type pile in an embodiment of the present invention (the left and right sides are two different boundary position situations).

[0042] Figure 5 It is a schematic diagram of the deflection of the principal stress distributed in the horizontal strip in the present invention.

[0043] Figure 6 It is a schematic diagram of a mechanical model of an embodiment of the present invention.

[0044] Figure 7 It is a schematic diagram of the embedding stability verification of an embodiment of the present invention.

[0045] Figure 8 is K of the embodiment of the present invention ci ,q ai ,q pi Calculation result diagram of .

[0046] In the attached drawings: 1-arch unit, 2-top plate, 3-hardening and intercepting ditch, 4-protection and drainage ditch, 1.1-Type A pile, 1.2-Type B pile, 1.3 grouting hole, 1.3.1-first grouting hole, 1.3.2-second grouting hole, 1.3.3-third grouting hole. DETAILED DESCRIPTION

[0047] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] Please refer to Figure 1-Figure 3 The embodiment of the present invention is located in the urban area, the landform is the Longgang area of ​​the third terrace of the Yangtze River, the site conditions are tight, the geotechnical engineering and hydrogeological conditions are simple, the soil layer of the side wall of the foundation pit is fill, hard plastic clay and sandstone, the excavation depth is 8 meters, and the importance level of the foundation pit is level 2. The foundation pit support needs to solve the problems of stabilizing the support structure, shortening the construction period, reducing costs and reducing the impact on the environment. In order to solve the above problems, a large-diameter sparse pile support method provided by the present invention is adopted.

[0049] Specifically, it relates to a large-diameter sparse pile support structure: it includes a plurality of arch units 1, a top plate 2, a hardening 3, a protection 4, a drainage ditch 5 and a drainage ditch 6. A plurality of arch units 1 are arranged along the edge of the foundation pit, the top plate 2 is arranged on the top of the arch unit 1 and connects the arch units, the hardening surface is arranged on the side of the horizontal top plate away from the foundation pit, the drainage ditch is arranged on one side of the hardening surface, the protection surface is closely attached to the inner side of the arch unit facing the foundation pit and is vertically distributed, and the drainage ditch is arranged at the bottom of the outer side of the protection surface;

[0050] The arch unit includes A-type piles, B-type piles and grouting holes; the A-type piles, B-type piles and grouting holes are all arranged vertically; the A-type piles are distributed at equal intervals near the edge of the foundation pit, and the A-type piles are located in the arch chord area of ​​the arch unit (i.e. Figure 1 The two end points of the area indicated by the dotted line are A-type piles at the joints shared by adjacent arch units; the B-type piles are located at the apex of the unit arch; and the grouting holes include a first grouting hole, a second grouting hole and a third grouting hole arranged in the unit arch chord area.

[0051] The first grouting hole and the second grouting hole are located at 1 / 4 and 3 / 4 of the unit arch chord; the third grouting hole is located at the midpoint of adjacent A-type piles.

[0052] The hardened surface, intercepting ditch and drainage ditch are all arranged horizontally; the hardened surface and protective surface are waterproof protective surfaces; the intercepting ditch and drainage ditch are drainage networks; and they are used to maintain the engineering properties of the soil.

[0053] The diameter of the A-type pile is larger than that of the B-type pile, ranging from 1.0 to 1.5 meters, and the center distance between two adjacent A-type piles is greater than 1.5D A +D B To make full use of the pile performance and improve economic efficiency, the center distance between two adjacent A-type piles (1.1) is less than or equal to 2.0D A +DB, prevents shear damage of soil between piles and forms soil arch to effectively support soil between piles. A is the diameter of type A pile, D B is the diameter of the B-type pile; the A-type pile resistance is greater than 1.2 times the combined earth pressure borne by the arch unit. A 1.5 meters, 3.1 meters apart, D B 0.8 m, L A It is 15.5 meters.

[0054] like Figure 4 The two boundary positions of the vertical distance H between the B-type pile and the midpoint of the A-type pile are shown. The diameter of the B-type pile is smaller than that of the A-type pile, and is 0.6 to 0.8 meters. The B-type pile is located at the highest point of the arch between two adjacent A-type piles (1.1) within the height range of the soil arch, and forms a soil arch with the A-type pile (1.1) to bear the force as a whole. The vertical distance H between the B-type pile and the midpoint of the two adjacent A-type piles is -0.5 (D A -D B )~0.5D A ; The length of the B-type pile is L h +4~L A ,L h is the depth of foundation pit, L A is the length of type A pile; D A is the diameter of type A pile, D B The lower end of the pile is buried in the hard soil layer and high pressure grouting is performed. In this embodiment, H is 0.75 meters and the length of the B-type pile is 13 meters.

[0055] The grouting hole 1.3 is formed by the grouting pipe and cement slurry solidified with the in-situ soil, which constrains the soil between the A-type pile 1.1 and the B-type pile 1.2, and has both soil retaining and water stopping functions. The cross-sectional inertia moment I of the arch unit 1 is π(0.0156D A 4 +0.0156D B 4 +0.25H 2 D B 2 ). Arch unit 1 is subjected to stress, and under the premise of increasing the spacing between A-type piles 1.1, it can still effectively support the soil outside the foundation pit. The cross-sectional inertia moment of the arch unit is much greater than the sum of the cross-sectional inertia moments of each pile. The resistance of A-type pile 1.1 is greater than 1.2 times the combined earth pressure borne by arch unit 1.

[0056] Please refer to Figures 5 to 8 As another aspect of the present invention, it also relates to a structural calculation method for a large-diameter sparse pile support structure, comprising the following steps:

[0057] Step 1: Determine the lateral earth pressure coefficient K based on the horizontal strip distribution ci And calculate the lateral earth pressure strength q ai and lateral earth pressure E ai ;

[0058] Step 2: Determine the soil reaction strength q in front of the pile using the elastic resistance method pi and the soil reaction force in front of the pile P pi ;

[0059] Step 3: Check the embedding stability and calculate the embedding depth l d and type A pile (1.1) pile length L;

[0060] Step 4: Calculate the internal force of the pile and design the structure based on the maximum shear force and maximum bending moment of the pile.

[0061] The method of step 1 is specifically as follows: the principal stress of the soil strip on the potential sliding surface is deflected, σ1 is the maximum principal stress, σ3 is the minimum principal stress, σ v is the vertical stress, σ h is the horizontal stress, K ai is the active earth pressure coefficient of the i-th soil layer, γ i is the soil density of the i-th layer, z i is the burial depth of the midpoint of the i-th soil strip, c i is the cohesion of the i-th soil layer, is the internal friction angle of the i-th soil layer, h is the excavation depth of the foundation pit, θ i is the deformation of the support structure at the calculation point of the i-th layer, a pn is the force arm of the nth layer of soil strip to the pile bottom, a pi is the force arm of the resultant reaction force of the i-th layer of soil on the pile bottom, a ai is the force arm of the active earth pressure on the pile bottom, z n is the burial depth of the midpoint of the nth layer of soil strip;

[0062] Maximum principal stress and rotation angle β i The relationship is:

[0063] because

[0064] Lateral earth pressure coefficient

[0065] Lateral earth pressure strength q ai =K ci γ i z i ;

[0066] Lateral earth pressure

[0067] The method of step 2 is specifically as follows:

[0068] Horizontal resistance coefficient of soil strip Soil reaction strength before pile q pi =K mi ·v i +γ i (z i -h)K ai ;

[0069] Resultant soil reaction force in front of pile

[0070] Furthermore, the specific method of step 3 is:

[0071] Embedded stability verification of arched elements Embedment depth l d =a pn +z n -h;

[0072] Type A pile (1.1) Pile length L = l d +h.

[0073] Furthermore, the specific method of step 4 is:

[0074] When pi =q ai When the maximum shear force of the pile is Q max =∑E ai -∑P pi ;

[0075] When ∑E ai =∑P pi When the maximum bending moment of the pile body is max =∑P pi a pi -∑E ai a ai ;

[0076] Thus, the diameter and spacing of the A-type piles (1.1) are determined.

[0077] In this embodiment, E ai =346KN / m, P p =926KN / m,l d =8m, D A =1.2m, spacing 2.9m, D B =0.8m.

[0078] The front edge of the top plate 2 is wider than the diameter of the A-type pile 1.1, and the rear edge is wider than the diameter of the B-type pile 1.2. The height of the top plate 2 is 0.6 to 0.8D. A The top plate 2 is connected to the components of the arch unit 1 by anchoring. In this embodiment, the top plate is 2.6 meters wide and 1.1 meters high.

[0079] The hardened surface and the protective surface are waterproof protective surfaces; the intercepting ditch and the drainage ditch are drainage networks; and they are used to maintain the engineering properties of the soil.

[0080] The beneficial effects of the present invention are:

[0081] 1. The arch structure has high rigidity and good stability.

[0082] 2. Convenient construction and high efficiency. The process is simple and provides barrier-free working space in the pit, which greatly shortens the construction period.

[0083] 3. Low consumables, good economy, green and low-carbon. It improves the problem of high consumables of dense piles, reduces costs and carbon emissions, and is environmentally friendly.

[0084] In the description of the embodiments of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invention patent product is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0085] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components must be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0086] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0087] It will be easily understood by those skilled in the art that 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 in the protection scope of the present invention.

Claims

1. A large-diameter sparse pile support structure, characterized in that: The invention comprises a plurality of arch units (1) arranged along the edge of a foundation pit, a horizontal top plate (2) arranged on the top of the arch units and connecting the arch units, a hardened surface (3) arranged on the side of the horizontal top plate (2) away from the foundation pit, a drainage ditch (5) arranged on one side of the hardened surface (3), a protective surface (4) vertically distributed close to the arch units (1) on the inner side of the foundation pit, and a drainage ditch (6) arranged at the bottom of the outer side of the protective surface (4); The arch unit (1) comprises an A-type pile (1.1), a B-type pile (1.2) and a grouting hole (1.3); the A-type pile (1.1), the B-type pile (1.2) and the grouting hole (1.3) are all arranged vertically; the A-type piles (1.1) are evenly spaced near the edge of the foundation pit, the A-type piles (1.1) are located at two end points of the arch chord area of ​​the arch unit, and adjacent arch units share the A-type piles (1.1) at the joint; the B-type pile (1.2) is located at the apex of the unit arch; the grouting holes comprise a first grouting hole (1.3.1), a second grouting hole (1.3.2) and a third grouting hole (1.3.3) arranged in the unit arch chord area.

2. A large-diameter sparse pile support structure according to claim 1, characterized in that: The first grouting hole (1.3.1) and the second grouting hole (1.3.2) are located at 1 / 4 and 3 / 4 of the unit arch chord; the third grouting hole (1.3.3) is located at the midpoint of adjacent A-type piles (1.1).

3. A large-diameter sparse pile support structure according to claim 1, characterized in that: The hardened surface (3), intercepting ditch (5) and drainage ditch (6) are all arranged horizontally; the hardened surface (3) and the protective surface (4) are waterproof protective surfaces; the intercepting ditch (5) and the drainage ditch (6) are a drainage network.

4. The large-diameter sparse pile support structure according to claim 1 is characterized in that: The diameter of the A-type pile (1.1) is greater than the diameter of the B-type pile (1.2), and is 1.0 to 1.5 meters. The center distance between two adjacent A-type piles (1.1) is greater than 1.5D. A +D B To fully exert the mechanical properties of the pile and improve economic efficiency, the center distance between two adjacent A-type piles (1.1) is less than or equal to 2.0D A +DB;D A is the diameter of type A pile (1.1), D B is the diameter of type B pile (1.2).

5. The large-diameter sparse pile support structure according to claim 1 is characterized in that: The diameter of the B-type pile (1.2) is smaller than that of the A-type pile (1.1), and is 0.6 to 0.8 meters. The B-type pile (1.2) is located at the highest point of the arch between two adjacent A-type piles (1.1) within the height range of the soil arch, and forms a soil arch with the A-type pile (1.1) to bear the force as a whole. The vertical distance H from the B-type pile (1.2) to the midpoint of the two adjacent A-type piles (1.1) is -0.5 (D A -D B )~0.5D A ; The length of the B-type pile (1.2) is L h +4~L A ,L h is the depth of foundation pit, L A is the length of type A pile (1.1); D A is the diameter of type A pile (1.1), D B is the diameter of the B-type pile (1.2); the lower end of the pile is buried in the hard soil layer and high-pressure grouting is performed.

6. The large-diameter sparse pile support structure according to claim 1 is characterized in that: The grouting hole (1.3) is formed by the grouting pipe and cement slurry solidified with the in-situ soil; the cross-sectional inertia moment I of the arch unit (1) is π(0.0156D A 4 +0.0156D B 4 +0.25H 2 D B 2 );D A is the diameter of type A pile (1.1), D B is the diameter of type B pile (1.2).

7. The large-diameter sparse pile support structure according to claim 1 is characterized in that: The front edge of the top plate (2) exceeds the outside diameter of the A-type pile (1.1), and the rear edge exceeds the outside diameter of the B-type pile (1.2); the height of the top plate (2) is 0.6 to 0.8D A ;D A is the diameter of type A pile (1.1).

8. The structural calculation method of the large-diameter sparse pile support structure according to claim 1 is characterized in that: The steps include: Step 1: Determine the lateral earth pressure coefficient K based on the horizontal strip distribution ci And calculate the lateral earth pressure strength q ai and lateral earth pressure E ai ; Step 2: Determine the soil reaction strength q in front of the pile using the elastic resistance method pi and the soil reaction force in front of the pile P pi ; Step 3: Check the embedding stability and calculate the embedding depth l d and type A pile (1.1) pile length L; Step 4: Calculate the internal force of the pile and design the structure based on the maximum shear force and maximum bending moment of the pile. The method of step 1 is specifically as follows: the principal stress of the soil strip on the potential sliding surface is deflected, σ1 is the maximum principal stress, σ3 is the minimum principal stress, σ v is the vertical stress, σ h is the horizontal stress, K ai is the active earth pressure coefficient of the i-th soil layer, γ i is the soil density of the i-th layer, z i is the burial depth of the midpoint of the i-th soil strip, c i is the cohesion of the i-th soil layer, is the internal friction angle of the i-th soil layer, h is the excavation depth of the foundation pit, θ i is the deformation of the support structure at the calculation point of the i-th layer, a pn is the force arm of the nth layer of soil strip to the pile bottom, a pi is the force arm of the resultant reaction force of the i-th layer of soil on the pile bottom, a ai is the force arm of the active earth pressure on the pile bottom, z n is the burial depth of the midpoint of the nth layer of soil strip; Maximum principal stress and rotation angle β i The relationship is: because Lateral earth pressure coefficient Lateral earth pressure strength q ai =K ci γ i z i ; Lateral earth pressure The method of step 2 is specifically as follows: Horizontal resistance coefficient of soil strip Soil reaction strength before pile q pi =K mi ·v i +γ i (z i -h)K ai ; Resultant reaction force of the earth 9. The structural calculation method of the large-diameter sparse pile support structure according to claim 8 is characterized in that: The specific method of step 3 is: Embedded stability verification of arched elements Embedment depth l d =a pn +z n -h; Type A pile (1.1) Pile length L = l d +h.

10. The structural calculation method of the large-diameter sparse pile support structure according to claim 9 is characterized in that: The specific method of step 4 is: When pi =q ai When the maximum shear force of the pile is Q max =∑E ai -∑P pi ; When ∑E ai =∑P pi When the maximum bending moment of the pile body is max =∑P pi a pi -∑E ai a ai ; Thus, the diameter and spacing of the A-type piles (1.1) are determined.

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