Double-row rigid composite pile connected support structure and stress analysis method

Abstract

The present invention discloses a double-row rigid composite pile connected support structure and a force analysis method, belonging to the technical field of building foundation pit support, the support structure includes front-row rigid composite piles, rear-row rigid composite piles, cement-soil pile connected grid, transverse connecting beam and longitudinal crown beam, the force analysis method adopts plane bar system finite element method, the cement-soil of the cement-soil pile connected grid only considers the compression effect, and is simulated by an equivalent single compression bar system, the analysis model uses spring units to simulate the constraints and forces of the front-row rigid composite piles and the rear-row rigid composite piles, and at the same time divides the front and rear-row rigid composite piles and the transverse connecting beam into multiple analysis units, establishes an overall stiffness matrix to perform finite element analysis under the support load, and finally obtains the overall mechanical response of the support structure and each component. The analysis method provided by the present invention is simple and practical, the analysis result is reliable, economical and reasonable, and easy to promote.

Description

Technical Field

[0001] The invention belongs to the technical field of building foundation pit support, and in particular relates to a double-row rigid composite pile connected support structure and a force analysis method. Background Art

[0002] After decades of rapid national development, my country's urban construction has reached saturation. As the number of open spaces in the core areas of large cities decreases, the following problems will arise:

[0003] The surrounding environment of the project under construction will become more and more complex. The construction of the project foundation pit may have a relatively large impact on the buildings around the project, especially the natural foundation buildings that may exist around the project. Foundation pit support is a support, reinforcement and protection measure for the side walls of the foundation pit and the surrounding environment to ensure the safety of underground structure construction and the surrounding environment of the foundation pit.

[0004] In the existing foundation pit support design, double-row pile support structure is widely used, and there are two methods:

[0005] 1) Double rows of precast piles, with cast-in-place transverse connecting beams on the tops of the front and rear piles;

[0006] 2) Double rows of bored piles with cast-in-place transverse connecting beams on top of the front and rear piles.

[0007] In these two methods, the front and rear piles and the transverse connecting beams together form a similar frame structure. Although the mechanical performance of the double-row pile support structure is better than that of the single-row cantilever support structure, it is limited by the mechanical characteristics of the frame and will produce the following disadvantages:

[0008] 1) The front and rear piles cannot form a whole to coordinate work well, the bending moment in the piles and the horizontal displacement of the support top are still large, the application scenarios are limited, and the scope of use of the double-row pile support structure is limited;

[0009] 2) The horizontal bearing capacity requirements of the front and rear piles are high, which leads to larger cross-sectional dimensions of the support piles, larger amounts of concrete and steel, and higher support construction costs and longer construction periods. Summary of the invention

[0010] In order to solve the above problems, the present invention discloses a double-row rigid composite pile connected support structure combined with a force analysis method, which can relatively accurately predict the displacement and force conditions of the double-row rigid composite pile connected support structure and make timely adjustments. The method is simple and has low calculation cost, can meet the engineering calculation accuracy requirements, and has strong reliability. The double-row rigid composite pile connected support structure scheme analyzed and calculated by this force analysis method is more economical and reasonable.

[0011] In order to achieve the above object, the technical solution of the present invention is as follows:

[0012] A double-row rigid composite pile connected support structure, the support structure includes a front row of rigid composite piles, a rear row of rigid composite piles, a longitudinal crown beam, a transverse connecting beam, a cement-soil pile connected grid and a cement-soil pile water-stop curtain, the tops of the front row of rigid composite piles and the rear row of rigid composite piles in the same transverse row are connected by the transverse connecting beam, and the front row of rigid composite piles or the rear row of rigid composite piles in the same longitudinal row are connected longitudinally by the longitudinal crown beam, so as to form a rigid continuously connected frame structure, the cement-soil pile water-stop curtain is arranged parallel to the side wall of the foundation pit, and the cement-soil pile connected grid is arranged between the front row of rigid composite piles and the rear row of rigid composite piles.

[0013] The present invention provides a stress analysis method based on a double-row rigid composite pile connected support structure. The double-row rigid composite pile connected support structure model to be analyzed includes a foundation pit top elevation, a foundation pit bottom elevation, a front-row rigid composite pile, a rear-row rigid composite pile, a longitudinal crown beam, a transverse connecting beam, an equivalent single-pressure diagonal rod, an equivalent single-pressure horizontal rod and a cement-soil pile connected grid. The tops of the front-row rigid composite piles and the rear-row rigid composite piles in the same transverse row are connected by the transverse connecting beam to form a rigid continuous connection. The frame structure is as follows: the front row of rigid composite piles or the rear row of rigid composite piles in the same longitudinal row are connected by the longitudinal crown beam; the cement-soil pile connected grid is arranged between the front row of rigid composite piles and the rear row of rigid composite piles; the force analysis method discretizes the cement-soil pile connected grid into an equivalent single-compression bar system, and the equivalent single-compression bar system includes an equivalent single-compression diagonal bar and an equivalent single-compression horizontal bar; the equivalent single-compression diagonal bar is arranged along the height direction of the support structure, along the height range of the support structure, and at the bottom elevation of the foundation pit. The positions near and above the bottom elevation of the foundation pit are equivalent single pressure inclined rods, and the rest are equivalent single pressure horizontal rods; the intersection elevation of the equivalent single pressure inclined rod and the front row rigid composite pile is lower than the intersection elevation with the rear row rigid composite pile, and the two ends of the equivalent single pressure inclined rod and the equivalent single pressure horizontal rod are connected to the front row rigid composite pile and the rear row rigid composite pile in a hinged manner. The analysis method is completed by establishing a two-dimensional plane analysis model using SAP2000 finite element software, and is applied to the front row rigid composite pile and The vertical spring unit simulating the side friction of the rear-row rigid composite pile, the vertical spring unit simulating the end resistance of the front-row rigid composite pile, and the normal spring unit simulating the passive horizontal earth pressure exerted by the soil in the pit on the front-row rigid composite pile when the supporting structure undergoes horizontal displacement are all created in the model. The front-row rigid composite piles, the rear-row rigid composite piles, the longitudinal cap beam, the transverse connecting beam and the equivalent single compression bar system are all simulated by beam units. The cross-sectional height of the equivalent single compression bar system is the discrete bar system spacing. h The bar width is the minimum thickness of the cement-soil pile grid. b , the rod system is set as an elastic rod, and the elastic modulus of the material E = α 1 E p = α 1α 2 f cu ,in:

[0014] E p ——Compression modulus of cement soil, unit: kN / m 2 ;

[0015] α 1——Proportional coefficient between elastic modulus and compression modulus of cement soil;

[0016] α 2——Proportional coefficient between compression modulus and strength of cement soil;

[0017] f cu ——The average value of the cubic compressive strength of the cement-soil test block at 90 days under standard curing conditions, in kPa;

[0018] The active earth pressure strength of the soil at the analysis point of the support structure p ak = gK a -2 c ( K a ) 0.5 The passive earth pressure strength of the soil at the analysis point of the support structure is p s0 = gK a ,

[0019] in:

[0020] p ak ——active earth pressure intensity, unit: kPa;

[0021] p s0 ——passive earth pressure intensity, unit: kPa;

[0022] K a ——Rankine active earth pressure coefficient;

[0023] γ ——Soil density, unit: kN / m 3 ;

[0024] c ——soil cohesion, in kPa;

[0025] z ——The depth of the analysis point from the ground, in meters.

[0026] As a further improvement of the analysis method of the present invention, when the pile spacing ba is large, the passive earth pressure analysis width is set to b 0, for circular piles, the passive earth pressure analysis width b0 analysis formula can be as follows:

[0027] b 0=0.9(1 .5 D +0.5), D ≤1.0m

[0028] b 0=0.9( D +1), D >1.0m;

[0029] Where: D ——The diameter of the peripheral piles of the rigid composite pile, in m.

[0030] As a further improvement of the analysis method of the present invention, the equivalent spring stiffness of the normal spring unit arranged in the front row of the rigid composite pile is k s = α s m ( z - h 0), m =(0.2 φ 2 - φ + c ) / v b ,in:

[0031] α s ——Correction coefficient of horizontal foundation reaction coefficient considering soil squeezing effect of rigid composite piles;

[0032] m ——Proportional coefficient of the horizontal reaction coefficient of the soil, unit: MN / m 4 ;

[0033] z ——The depth of the calculation point from the ground, in meters;

[0034] h 0——excavation depth of supporting foundation pit, unit: m;

[0035] c , φ ——respectively, the cohesion of soil, in kPa, and the internal friction angle, in °;

[0036] v b ——Horizontal displacement of the supporting structure at the bottom of the foundation pit, in mm.

[0037] The beneficial effects of the present invention are as follows:

[0038] (1) The analysis method is simple and practical: The analysis method of the present invention uses an equivalent single compression bar system to simulate the cement-soil pile grid between the front row of rigid composite piles and the rear row of rigid composite piles, and uses a spring unit to simulate the pile side friction, pile end resistance and passive soil force of the front row of rigid composite piles under horizontal deformation. The above method is simple and has low analysis cost.

[0039] (2) The analysis results are reasonable and reliable: The analysis method described in the present invention fully reflects the beneficial effect of the cement-soil pile integrated grid on the stress of the supporting structure, and takes into account the mechanical characteristics of the cement-soil pile integrated grid that the cement-soil cannot be subjected to tension, thereby avoiding the occurrence of tensile stress in the cement-soil. The processing idea is reasonable and prudent, and is compared and verified with actual projects, indicating that the analysis method can meet the accuracy requirements of engineering analysis and has strong reliability.

[0040] (3) Green, energy-saving, and economical: The analysis method of the present invention is highly consistent with the stress mode of the double-row rigid composite pile connected support structure. Compared with the results obtained by the conventional double-row pile support analysis method provided in the Technical Code for Building Foundation Pit Support (JGJ120-2012), the analysis results show that both the displacement and the bending moment of the support structure are greatly reduced. Therefore, the double-row rigid composite pile connected support structure scheme analyzed by the analysis method of the present invention is more economical and reasonable.

[0041] In summary, the double-row rigid composite pile one-piece support structure of the present invention is equivalent to a single compression rod system simulating a cement-soil pile one-piece grid and can more accurately predict the displacement and stress conditions of the double-row rigid composite pile one-piece support structure. The stress analysis method provided by the present invention is simple, the results are reasonable, the reliability is strong, the analysis cost is low, and the design scheme is economical and reasonable, which makes the stress analysis method of the double-row rigid composite pile one-piece support structure easy to be applied and popularized by engineering and technical personnel, and is also conducive to the use and promotion of the double-row rigid composite pile one-piece support structure in the field of foundation pit engineering, and has great practical application value and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic elevation view of a double-row rigid composite pile connected support structure of the present invention.

[0043] Figure 2 yes Figure 1 Sectional view of the AA support structure.

[0044] Figure 3 It is a schematic diagram of a force model of a force analysis method for a double-row rigid composite pile connected support structure of the present invention.

[0045] Figure 4It is a displacement curve diagram of the supporting structure obtained by analyzing the analysis method of the present invention.

[0046] Figure 5 It is the bending moment diagram of the supporting structure obtained by analyzing the analysis method of the present invention.

[0047] List of Figure Symbols:

[0048] 1. Elevation of the top of the foundation pit; 2. Elevation of the bottom of the foundation pit; 3. Front row rigid composite piles; 4. Rear row rigid composite piles; 5. Longitudinal crown beam; 6. Transverse connecting beam; 7. Equivalent single pressure diagonal rod; 8. Equivalent single pressure horizontal rod; 9. Cement soil pile connected grid; 10. Cement soil pile water stop curtain; 11. Side wall of the foundation pit; 12-1. Vertical spring unit applied to the front row rigid composite piles and the rear row rigid composite piles to simulate the pile side friction resistance; 12-2. Vertical spring unit simulating the pile end resistance of the front row rigid composite piles; 12-3. Normal spring unit simulating the passive horizontal earth pressure applied by the soil in the pit to the front row rigid composite piles when the support structure undergoes horizontal displacement; H , foundation pit depth; L d , embedment depth of support piles; S y , the distance between the front and rear rows of piles; p s , comprehensive passive earth pressure, unit: kPa; p ak , the standard value of active earth pressure strength at the analysis point in the i-th layer of soil outside the supporting structure, in kPa; b a , pile spacing; b 0. Passive earth pressure analysis width; D. Diameter of the outer pile of the rigid composite pile. Implementation

[0049] The present invention will be further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0050] A double-row rigid composite pile connected support structure, the support structure includes a front row of rigid composite piles, a rear row of rigid composite piles, a longitudinal crown beam, a transverse connecting beam, a cement-soil pile connected grid and a cement-soil pile water-stop curtain, the tops of the front row of rigid composite piles and the rear row of rigid composite piles in the same transverse row are connected by the transverse connecting beam, and the front row of rigid composite piles or the rear row of rigid composite piles in the same longitudinal row are connected longitudinally by the longitudinal crown beam, so as to form a rigid continuously connected frame structure, the cement-soil pile water-stop curtain is arranged parallel to the side wall of the foundation pit, and the cement-soil pile connected grid is arranged between the front row of rigid composite piles and the rear row of rigid composite piles.

[0051] The present invention provides a stress analysis method based on a double-row rigid composite pile connected support structure. The double-row rigid composite pile connected support structure model to be analyzed includes a foundation pit top elevation, a foundation pit bottom elevation, a front-row rigid composite pile, a rear-row rigid composite pile, a longitudinal crown beam, a transverse connecting beam, an equivalent single-pressure diagonal rod, an equivalent single-pressure horizontal rod and a cement-soil pile connected grid. The tops of the front-row rigid composite piles and the rear-row rigid composite piles in the same transverse row are connected by the transverse connecting beam to form a rigid continuous connection. The frame structure is as follows: the front row of rigid composite piles or the rear row of rigid composite piles in the same longitudinal row are connected by the longitudinal crown beam; the cement-soil pile connected grid is arranged between the front row of rigid composite piles and the rear row of rigid composite piles; the force analysis method discretizes the cement-soil pile connected grid into an equivalent single-compression bar system, and the equivalent single-compression bar system includes an equivalent single-compression diagonal bar and an equivalent single-compression horizontal bar; the equivalent single-compression diagonal bar is arranged along the height direction of the support structure, along the height range of the support structure, and at the bottom elevation of the foundation pit. The positions near and above the bottom elevation of the foundation pit are equivalent single pressure inclined rods, and the rest are equivalent single pressure horizontal rods; the intersection elevation of the equivalent single pressure inclined rod and the front row rigid composite pile is lower than the intersection elevation with the rear row rigid composite pile, and the two ends of the equivalent single pressure inclined rod and the equivalent single pressure horizontal rod are connected to the front row rigid composite pile and the rear row rigid composite pile in a hinged manner. The analysis method is completed by establishing a two-dimensional plane analysis model using SAP2000 finite element software, and is applied to the front row rigid composite pile and The vertical spring unit simulating the side friction of the rear-row rigid composite pile, the vertical spring unit simulating the end resistance of the front-row rigid composite pile, and the normal spring unit simulating the passive horizontal earth pressure exerted by the soil in the pit on the front-row rigid composite pile when the supporting structure undergoes horizontal displacement are all created in the model. The front-row rigid composite piles, the rear-row rigid composite piles, the longitudinal cap beam, the transverse connecting beam and the equivalent single compression bar system are all simulated by beam units. The cross-sectional height of the equivalent single compression bar system is the discrete bar system spacing. h The bar width is the minimum thickness of the cement-soil pile grid. b , the rod system is set as an elastic rod, and the elastic modulus of the material E = α 1 E p = α 1 α 2 f cu ,in:

[0052] E p ——Compression modulus of cement soil, unit: kN / m 2 ;

[0053] α 1——Proportional coefficient between elastic modulus and compression modulus of cement soil;

[0054] α2——Proportional coefficient between compression modulus and strength of cement soil;

[0055] f cu ——The average value of the cubic compressive strength of the cement-soil test block at 90 days under standard curing conditions, in kPa;

[0056] The active earth pressure strength of the soil at the analysis point of the support structure p ak = gK a -2 c ( K a ) 0.5 The passive earth pressure strength of the soil at the analysis point of the support structure is p s0 = gK a ,

[0057] in:

[0058] p ak ——active earth pressure intensity, unit: kPa;

[0059] p s0 ——passive earth pressure intensity, unit: kPa;

[0060] K a ——Rankine active earth pressure coefficient;

[0061] γ ——Soil density, unit: kN / m 3 ;

[0062] c ——soil cohesion, in kPa;

[0063] z ——The depth of the analysis point from the ground, in meters.

[0064] As a further improvement of the analysis method of the present invention, when the pile spacing ba is large, the passive earth pressure analysis width is set to b 0, for circular piles, the passive earth pressure analysis width b0 analysis formula can be as follows:

[0065] b 0=0.9(1 .5 D +0.5), D ≤1.0m

[0066] b 0=0.9( D +1), D>1.0m;

[0067] Where: D ——The diameter of the peripheral piles of the rigid composite pile, in m.

[0068] As a further improvement of the analysis method of the present invention, the equivalent spring stiffness of the normal spring unit arranged in the front row of the rigid composite pile is k s = α s m ( z - h 0), m =(0.2 φ 2 - φ + c ) / v b ,in:

[0069] α s ——Correction coefficient of horizontal foundation reaction coefficient considering soil squeezing effect of rigid composite piles;

[0070] m ——Proportional coefficient of the horizontal reaction coefficient of the soil, unit: MN / m 4 ;

[0071] z ——The depth of the calculation point from the ground, in meters;

[0072] h 0——excavation depth of supporting foundation pit, unit: m;

[0073] c , φ ——respectively, the cohesion of soil, in kPa, and the internal friction angle, in °;

[0074] v b ——Horizontal displacement of the supporting structure at the bottom of the foundation pit, in mm.

[0075] The conventional double-row pile support analysis method provided by the Technical Code for Building Foundation Pit Support (JGJ120-2012). According to the analysis method of the present invention, the maximum support displacement is 28.5mm; using the conventional double-row pile support analysis method provided by the Technical Code for Building Foundation Pit Support (JGJ120-2012), the maximum support displacement is 44.3mm; after the excavation of the foundation pit of the actual support project, the maximum displacement is 26.0mm. By comparison, it can be seen that the support displacement result obtained by the analysis method of the present invention is close to the actual displacement value; the support displacement result obtained by the method provided by the Technical Code for Building Foundation Pit Support (JGJ120-2012) is very different from the actual displacement, with a difference of about 70%, and cannot be used as an engineering application. It can be seen that the analysis method of the present invention is more accurate in simulating the double-row rigid composite pile connected support structure, has strong adaptability, and can better predict the displacement of this type of support structure. In addition, the support displacement result obtained by the analysis method of the present invention is greater than the support displacement of the actual project; if the analysis method of the present invention is extended to the analysis of support engineering, it is relatively safe and has a certain surplus safety margin, which is relatively safe and reliable.

[0076] The displacement response of the support structure is closely related to the internal force response of the support structure. The bending moment results of the support structure are as follows: Figure 5 , the "reference standard method" in the figure is the conventional double-row pile support analysis method provided by the "Technical Code for Building Foundation Pit Support" (JGJ120-2012). The maximum bending moment of the front row rigid composite piles 3 and the rear row rigid composite piles 4 obtained by the conventional double-row pile support analysis method provided by the "Technical Code for Building Foundation Pit Support" (JGJ120-2012) is 214.1kN·m; the maximum bending moment of the front row rigid composite piles 3 and the rear row rigid composite piles 4 obtained by the analysis method of the present invention is 108.6kN·m, which is about 50% less than the analysis result according to the aforementioned standard, and the bending moment is greatly reduced.

[0077] The present invention proposes a stress analysis method for a double-row rigid composite pile connected support structure, which adopts a plane rod finite element analysis method, and introduces in detail the method for establishing a finite element model and determining related parameters; the SAP2000 finite element analysis software is used to verify and analyze the actual project according to the analysis method of the present invention, and the analysis results are compared with the actual project detection results; at the same time, the bending moment results of the method of the present invention are compared with the bending moment results obtained by the conventional double-row pile support analysis method provided in the "Technical Code for Building Foundation Pit Support" (JGJ120-2012). The analysis method of the present invention has the following characteristics:

[0078] (1) The analysis method is simple and practical: The analysis method of the present invention uses an equivalent single compression rod system to simulate the cement-soil pile grid 9 between the front row rigid composite piles 3 and the rear row rigid composite piles 4; at the same time, a spring unit 12 is used to simulate the pile side friction, pile end resistance and passive soil force of the front row rigid composite piles 3 under horizontal deformation. The above method is simple and has low analysis cost.

[0079] (2) The analysis results are reasonable and reliable: The analysis method described in the present invention fully reflects the beneficial effect of the cement-soil pile integrated grid 9 on the stress of the supporting structure, and takes into account the mechanical characteristics of the cement soil of the cement-soil pile integrated grid 9 that the cement soil cannot be subjected to tension, thereby avoiding the occurrence of tensile stress in the cement soil. The processing idea is reasonable and prudent; and the comparison and verification with the actual project shows that the analysis method can meet the accuracy requirements of engineering analysis and has strong reliability.

[0080] (3) Green, energy-saving, and economical: The analysis method of the present invention is highly consistent with the stress mode of the double-row rigid composite pile connected support structure. Compared with the results obtained by the conventional double-row pile support analysis method provided in the Technical Code for Building Foundation Pit Support (JGJ120-2012), the analysis results show that both the displacement and the bending moment of the support structure are greatly reduced. Therefore, the double-row rigid composite pile connected support structure scheme analyzed by the analysis method of the present invention is more economical and reasonable.

[0081] In summary, the double-row rigid composite pile one-piece support structure of the present invention is equivalent to a single compression rod system simulating a cement-soil pile one-piece grid and can more accurately predict the displacement and stress conditions of the double-row rigid composite pile one-piece support structure. The stress analysis method provided by the present invention is simple, the results are reasonable, the reliability is strong, the analysis cost is low, and the design scheme is economical and reasonable, which makes the stress analysis method of the double-row rigid composite pile one-piece support structure easy to be applied and popularized by engineering and technical personnel, and is also conducive to the use and promotion of the double-row rigid composite pile one-piece support structure in the field of foundation pit engineering, and has great practical application value and broad application prospects.

[0082] It should be noted that the above content only illustrates the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications all fall within the protection scope of the claims of the present invention.

Claims

1. A stress analysis method for a double-row rigid composite pile connected support structure, the double-row rigid composite pile connected support structure comprising a front-row rigid composite pile (3), a rear-row rigid composite pile (4), a longitudinal crown beam (5), a transverse connecting beam (6), a cement-soil pile connected grid (9) and a cement-soil pile water-stop curtain (10); the tops of the front-row rigid composite pile (3) and the rear-row rigid composite pile (4) in the same transverse row are connected by the transverse connecting beam (6) to form a rigid continuous connected frame structure; the cement-soil pile connected grid (9) is arranged between the front-row rigid composite pile (3) and the rear-row rigid composite pile (4) The cement-soil pile combined grid (9) is interlocked with the front row rigid composite piles (3) at one end, and interlocked with the rear row rigid composite piles (4) at the other end; the cement-soil pile combined grid (9) is composed of a plurality of cement-soil piles, and the plurality of cement-soil piles are interlocked with each other; the front row rigid composite piles (3) or the rear row rigid composite piles (4) in the same longitudinal row are connected in the longitudinal direction by the longitudinal crown beam (5), and the cement-soil pile water-stop curtain (10) is arranged in parallel with the side wall (11) of the foundation pit, characterized in that: The double-row rigid composite pile connected support structure model to be analyzed comprises a foundation pit top elevation (1), a foundation pit bottom elevation (2), a front row rigid composite pile (3), a rear row rigid composite pile (4), a longitudinal crown beam (5), a transverse connecting beam (6), an equivalent single pressure diagonal rod (7), an equivalent single pressure horizontal rod (8) and a cement soil pile connected grid (9), wherein the top ends of the front row rigid composite pile (3) and the rear row rigid composite pile (4) in the same transverse row are connected by the transverse connecting beam (6) to form a rigid continuous connected frame structure; the front row rigid composite piles in the same longitudinal row are connected by the transverse connecting beam (6) to form a rigid continuous connected frame structure; (3) or the longitudinal direction of the rear row of rigid composite piles (4) are connected by the longitudinal crown beam (5); the cement soil pile joint grid (9) is arranged between the front row of rigid composite piles (3) and the rear row of rigid composite piles (4); the force analysis method discretizes the cement soil pile joint grid (9) into an equivalent single pressure bar system; the equivalent single pressure bar system includes an equivalent single pressure diagonal bar (7) and an equivalent single pressure horizontal bar (8); the equivalent single pressure diagonal bar (7) is arranged along the height direction of the supporting structure, along the height range of the supporting structure, near the foundation pit bottom elevation (2) and above the foundation pit bottom elevation (2) The upper position is an equivalent single pressure inclined rod (7), and the rest are equivalent single pressure horizontal rods (8); the intersection elevation of the equivalent single pressure inclined rod (7) and the front row rigid composite pile (3) is lower than the intersection elevation of the equivalent single pressure inclined rod (7) and the rear row rigid composite pile (4); the two ends of the equivalent single pressure inclined rod (7) and the equivalent single pressure horizontal rod (8) are connected to the front row rigid composite pile (3) and the rear row rigid composite pile (4) in a hinged manner; the analysis method is completed by using SAP2000 finite element software to establish a two-dimensional plane analysis model, and is applied to the front row rigid composite pile (3) and the rear row rigid composite pile (4). A vertical spring unit (12-1) for simulating the pile side friction resistance of the combined pile (4), a vertical spring unit (12-2) for simulating the pile end resistance of the front row rigid composite pile (3), and a normal spring unit (12-3) for simulating the passive horizontal earth pressure exerted by the soil in the pit on the front row rigid composite pile (3) when the supporting structure undergoes horizontal displacement are all created in the model. The front row rigid composite pile (3), the rear row rigid composite pile (4), the transverse connecting beam (6) and the equivalent single compression bar system are all simulated using beam units. The cross-sectional height of the equivalent single compression bar system is the discrete bar system spacing. h The width of the rod system is the minimum thickness of the cement-soil pile grid (9). b , the rod system is set as an elastic rod, and the elastic modulus of the material E = α 1 E p = α 1 α 2 f cu ,in: E p ——Compression modulus of cement soil, unit: kN / m 2 ; α 1——Proportional coefficient between elastic modulus and compression modulus of cement soil; α 2——Proportional coefficient between compression modulus and strength of cement soil; f cu ——The average value of the cubic compressive strength of the cement-soil test block at 90 days under standard curing conditions, in kPa; The active earth pressure strength of the soil at the analysis point of the support structure p ak = γzK a -2 c ( K a ) 0.5 The passive earth pressure strength of the soil at the analysis point of the support structure is p s0 = γzK a , Among them: p ak ——active earth pressure intensity, unit: kPa; p s0 ——passive earth pressure intensity, unit: kPa; K a ——Rankine active earth pressure coefficient; c ——Soil density, unit: kN / m 3 ; c ——soil cohesion, in kPa; z ——The depth of the analysis point from the ground, in meters.

2. The stress analysis method of a double-row rigid composite pile connected support structure according to claim 1 is characterized in that: When the pile spacing ba is large, the passive earth pressure analysis width is set b 0, for circular piles, the passive earth pressure analysis width b0 analysis formula can be as follows: b 0=0.9（1 .5 D +0 .5）， D ≤1.0m b 0=0.9（ D +1）， D >1.0m； Where: D ——The diameter of the peripheral piles of the rigid composite pile, in m.

3. The stress analysis method of a double-row rigid composite pile connected support structure according to claim 2 is characterized in that: The equivalent spring stiffness of the normal spring unit (12-3) simulating the passive horizontal earth pressure exerted by the soil in the pit on the front row of rigid composite piles (3) when the supporting structure undergoes horizontal displacement k s = α s m ( z - h 0), m =(0.2 f 2 - f + c ) / v b ,in: α s ——Correction coefficient of horizontal foundation reaction coefficient considering soil squeezing effect of rigid composite piles; m ——Proportional coefficient of the horizontal reaction coefficient of the soil, unit: MN / m 4 ; z ——The depth of the calculation point from the ground, in meters; h 0——excavation depth of supporting foundation pit, unit: m; c , f ——respectively, the cohesion of soil, in kPa, and the internal friction angle, in °; v b ——Horizontal displacement of the supporting structure at the bottom of the foundation pit, in mm.

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