A system and method for calculating the stability of embedded rock support piles in rigid-flexible composite foundation pits

Abstract

The present invention relates to a method and system for checking the rock-embedded stability of supporting piles for rigid-flexible composite foundation pits. The processor in the system is configured to: establish a model of the relative position relationship between the foundation pit position and the stratum based on geological parameters related to the foundation pit position, and set the embedding depth parameter and the design width parameter of the rock shoulder; in the embedded pile stage, calculate the critical rock-embedded depth parameter based on the first active soil parameter outside the foundation pit above the rock-embedded surface, the rock mass horizontal resistance resultant force parameter, and the second distance parameter from the sixth support to the pile bottom; in the hanging pile stage, calculate the critical rock shoulder width parameter based on the second active soil parameter and the fourth distance parameter from the second support to the fourth support; judge whether the embedding depth parameter and the design width parameter of the rock shoulder meet the stability checking conditions according to the first mechanical model and the second mechanical model. The method and system for determining the critical rock-embedded depth and the critical rock shoulder width of the present invention help to check the rock-embedded stability of supporting piles in rigid-flexible composite foundation pits.

Description

Technical Field

[0001] The invention relates to the technical field of geotechnical engineering, and in particular to a rock-embedded stability calculation system and method for supporting piles used in a rigid-flexible composite foundation pit. Background Art

[0002] With the development of urban rail transit construction in my country, complex and differentiated engineering geological environments continue to emerge, bringing new challenges and opportunities to urban rail transit engineering construction. The soil-rock combination stratum is a typical complex engineering geological environment. The physical and mechanical properties of the upper soil layer and the lower rock layer, such as strength, stiffness, permeability, and stability, are significantly different. Therefore, there are great differences in excavation methods and the difficulty of pile formation. The stratum as a whole presents the characteristics of "soft on top and hard on the bottom". The open-cut method is the most commonly used and economical method for constructing subway stations. It is widely used in the urban rail transit engineering construction industry. In cities with upper soil and lower rock, a "rigid on top and soft on the bottom" rigid-flexible composite support system is needed to ensure the safety of open-cut deep foundation pits. At present, the industry widely uses partially embedded "hanging piles" as the foundation pit support structure of the upper soft soil stratum in the soil-rock combination stratum. This foundation pit support system of upper "hanging piles" + lower sprayed anchor support is called a rigid-flexible composite foundation pit support system.

[0003] "Dangling piles" refer to a type of support pile in foundation pit engineering, which refers to retaining piles with the bottom of the support pile above the bottom of the foundation pit and the pile body fully exposed. In recent years, sling piles have been continuously used in deep foundation pit engineering support in many places, achieving good support effects and significant benefits. However, the theoretical research on sling piles is still far behind the engineering, and the calculation method of the foundation pit retaining structure in the traditional soft soil area is still followed when performing structural calculations, which will lead to two problems. First, in the rigid-flexible composite support system, the upper support piles will go through two stages: embedded piles and sling piles. When the foundation pit is excavated below the pile bottom, the support piles enter the sling pile stage, and the horizontal resistance provided by the rock mass in the embedded rock section to the sling piles will be greatly reduced. This is the main difference between sling piles and embedded piles. The traditional calculation method only calculates the support pile structure as an embedded pile, and does not consider the calculation of the sling pile structure when the foundation pit is excavated below the pile bottom. Second, the geological differences between the upper soil and the lower rock are not taken into account. The traditional calculation method of active earth pressure and passive earth pressure is based on the Rankine earth pressure theory, which is more in line with the characteristics of soft soil. If the Rankine earth pressure theory is used to calculate the active earth pressure and passive earth pressure for the harder rock-embedded part of the support pile, some problems will arise.

[0004] Therefore, in view of the above-mentioned defects, the present invention, through intensive research and design, integrates the experience and achievements of long-term engagement in related industries, and applies the Hoek-Brown strength criterion, which is widely used internationally, to the horizontal resistance calculation of the rock-embedded part of the support pile. The structural stress characteristics and failure modes of the entire process of hanging pile construction are studied in depth, and a calculation method and system for the rock-embedded depth and reserved rock shoulder width of the upper support pile in the hanging pile stage are proposed, forming a guiding method and system for checking the rock-embedded stability of the support pile of the rigid-flexible composite foundation pit support system.

[0005] In addition, on the one hand, there are differences in understanding among those skilled in the art; on the other hand, the applicant studied a large number of documents and patents when making the present invention, but due to space limitations, not all details and contents are listed in detail. However, this does not mean that the present invention does not have the characteristics of these prior arts. On the contrary, the present invention already has all the characteristics of the prior art, and the applicant reserves the right to add relevant prior art to the background technology. Summary of the invention

[0006] The existing technology still follows the traditional calculation method of foundation pit retaining structure in soft soil areas when performing structural calculations, which will lead to two problems. First, in the rigid-flexible composite support system, the upper support piles will go through two stages: embedded piles and hanging piles. When the foundation pit is excavated below the pile bottom, the support piles enter the hanging pile stage. The horizontal resistance provided by the rock mass in the rock-embedded section to the hanging piles will be greatly reduced. This is the main difference between hanging piles and embedded piles. The traditional calculation method only calculates the support pile structure as an embedded pile without considering the calculation of the hanging pile structure after the foundation pit is excavated below the pile bottom. Second, the stratigraphic differences between the upper soil and the lower rock are not considered. The traditional calculation method of active earth pressure and passive earth pressure is based on the Rankine earth pressure theory. The Rankine earth pressure theory is more in line with the characteristics of soft soil. If the Rankine earth pressure theory is used to calculate the active earth pressure and passive earth pressure of the rock-embedded part of the support pile, some problems will arise.

[0007] In view of the deficiencies of the prior art, the present invention provides a rock-embedded stability verification system for supporting piles of rigid-flexible composite foundation pits from a first aspect, including a processor. The processor is configured to: establish a model of the relative position relationship between the foundation pit position and the stratum based on geological parameters related to the foundation pit position, and set the embedding depth parameter and the design width parameter of the rock shoulder; in the embedded pile stage, calculate the critical rock-embedded depth parameter based on the first active soil parameter of the outside of the foundation pit above the embedded rock surface, the rock mass horizontal resistance resultant force parameter provided by the rock mass below the embedded rock surface, and the second distance parameter from the sixth support to the pile bottom; in the hanging pile stage, calculate the critical rock shoulder width parameter based on the second active soil parameter of the outside of the foundation pit below the second support and the fourth distance parameter from the second support to the fourth support; judge whether the embedding depth parameter and the design width parameter of the rock shoulder meet the stability verification conditions according to the first mechanical model and the second mechanical model. The horizontal resistance resultant of the rock shoulder can be understood as the combined effect of the active earth pressure and the passive earth pressure of the rock-embedded section.

[0008] The present invention improves the calculation method of the horizontal resistance provided by the rock mass below the rock-embedded surface in the embedded pile stage by using the Hoek-Brown strength criterion, and divides the calculation of the supporting piles into the embedded pile stage and the hanging pile stage. In the embedded pile stage, the critical rock-embedded depth of the supporting piles is calculated according to the stability requirements of the foundation pit, and the critical rock-embedded depth is calculated according to the embedded pile stage. In the hanging pile stage, the critical rock shoulder width is obtained by the kicking stability calculation. The present invention takes into account the problem that the horizontal resistance provided by the rock mass of the rock-embedded section to the hanging piles will be greatly reduced when the foundation pit is excavated below the pile bottom and the supporting piles enter the hanging pile stage. By analyzing the two different stability failure modes of the embedded pile stage and the hanging pile stage, two limit equilibrium equations (the first mechanical model and the second mechanical model) are obtained, thereby providing a method that can help determine the two key design parameters of the critical rock-embedded depth and the critical rock shoulder width, which can help verify the rock-embedded stability of the supporting piles of the rigid-flexible composite foundation pit support system.

[0009] According to a preferred embodiment, the processor calculates the first active soil parameter outside the foundation pit above the rock-embedded surface in a manner including: calculating the active soil pressure parameter outside the foundation pit above the rock surface; calculating the active soil resistance parameter outside the foundation pit above the rock surface and the first distance parameter from the fifth support point to the pile bottom; the fifth support point is the action point of the active soil resistance on the supporting pile. Above the rock-embedded surface, the soil pressure action point outside the supporting pile is basically located between the active soil pressure action point and the static soil pressure action point. By calculating the active soil pressure parameter outside the foundation pit above the rock-embedded surface and the first distance parameter, it is helpful to determine the resultant force on the supporting pile part above the rock-embedded surface.

[0010] According to a preferred embodiment, the processor calculates the rock mass horizontal resistance resultant force parameters provided by the rock mass below the rock-embedded surface in the following manner: calculating the pile side limit resistance parameters on the inner side of the foundation pit below the rock surface according to the Hoek-Brown strength criterion; calculating the rock mass horizontal resistance resultant force parameters provided by the rock mass below the rock-embedded surface in the pile embedding stage and the second distance parameter from the sixth fulcrum to the pile bottom, the sixth fulcrum being the point of action of the rock mass horizontal resistance resultant force on the supporting pile. Below the rock-embedded surface, since the underlying bedrock is of good quality and there is rock mass inside and outside the supporting pile, the horizontal displacement of the pile is greater than the displacement of the rock mass, and the hanging pile is very likely to have been separated from the medium-weathered granite or relaxed, that is, a gap has been created with the rock mass, so the active earth pressure outside the supporting pile at the soil-rock interface is zero. The passive earth pressure below the rock-embedded surface is quite different from the Rankine passive earth pressure in terms of distribution form and value. By calculating the resultant force on the support pile below the rock-embedded surface and the second distance parameter, the numerical simulation results show that the soil pressure on the inner side of the support pile at the rock-embedded surface is the largest and decreases with the depth of the support pile buried in the rock.

[0011] According to a preferred embodiment, the processor calculates the critical rock-embedded depth parameter in a manner including: selecting the minimum rock-embedded depth value that conforms to the first mechanical model as the critical rock-embedded depth parameter; wherein the first mechanical model is: E p1 h p1 +T c1 (h t1 +h d )-K E E A1 h a1 ≥0; E P1 Indicates the horizontal resistance parameter of rock mass; h a1 Indicates the first distance parameter from the fifth support point to the pile bottom; h p1 Indicates the second distance parameter from the sixth support point to the pile bottom; T c1 h represents the axial force parameter of the upper support point during the pile embedding stage; T1 Indicates the vertical distance from the first support point to the excavation surface of the foundation pit; h d represents the critical rock-embedded depth parameter; K e E represents the safety factor of rock-embedded stability; a1 Represents the active soil resistance parameter. For the rock-embedded depth of the support piles, the present invention designs the support structure according to the most unfavorable effect condition. In the construction process considered by the present invention, the most unfavorable effect condition of the embedded pile stage is the condition 3 in the embodiment. At this time, the foundation pit is excavated below the soil-rock interface, and the lowest row of anchor cables / supports have not yet been constructed. If the rock-embedded depth is not enough, it is easy to be damaged. The failure mode mainly considers the rotation and displacement of the support piles around the bottom of the pile. The critical rock-embedded depth obtained according to this extreme case and the first mechanical model is the minimum rock-embedded depth. Only the rock-embedded depth greater than the critical rock-embedded depth can achieve a better support effect.

[0012] According to a preferred embodiment, the processor calculates the second active soil parameter outside the foundation pit below the second support point in a manner including: calculating the active soil pressure resultant force parameter outside the foundation pit below the second support point; calculating the third distance parameter from the second support point to the third support point; the third support point is the point of action of the active soil pressure resultant force of the outer layer of the foundation pit below the second support point on the support pile. By calculating the resultant force of the rock mass below the rock-embedded surface on the support pile and the third distance parameter, data support can be provided for the calculation of the second mechanical model.

[0013] According to a preferred embodiment, the processor calculates the critical shoulder width parameter in a manner including: selecting the minimum shoulder width value that conforms to the second mechanical model as the critical shoulder width parameter; wherein the second mechanical model is: E P2 h p2 ≥K T E a2 h a2 ; E P2 h is the parameter of the resultant horizontal resistance of the rock shoulder; p2 It represents the fourth distance parameter from the second support point to the fourth support point; the fourth support point is the point where the combined force of the horizontal resistance of the rock shoulder acts on the supporting pile; K T Indicates the stability safety factor of the kicking foot; E a2 It represents the active earth pressure parameter outside the foundation pit below the second support point; h a2 Represents the third distance parameter from the second fulcrum to the third fulcrum.

[0014] The design problem of the critical rock shoulder width of the support pile is mainly reflected in the working condition 5 in the embodiment. Due to the excavation of the "inner pit", only the rocks within the rock shoulder width have a restraining effect on the rock-embedded section of the support pile, so the rock shoulder part is prone to danger due to insufficient strength. In the calculation of the critical rock shoulder width, the stability of the kicking is mainly considered. When the restraint effect on the rock-embedded section is limited, the upper displacement of the support pile is very small, but the bottom of the support pile will produce a large positive displacement, which is manifested as a rotation around the anchor cable or the supporting fulcrum. Therefore, the critical rock-embedded depth parameter obtained by designing the second mechanical model of the present invention provides construction personnel with very favorable reference information for the rock-embedded stability of the support pile.

[0015] According to a preferred embodiment, the processor is further configured to: when the embedding depth parameter does not meet the conditions of the first mechanical model, the information generated by the processor includes: increasing the embedding depth; when the design width parameter of the rock shoulder does not meet the conditions of the second mechanical model, the information generated by the processor includes: increasing the design width of the rock shoulder. The processor of the present invention can use the first mechanical model and the second mechanical model to quickly verify the rock embedding stability of the supporting piles of the support system of the rigid-flexible composite foundation pit, and give appropriate support suggestions.

[0016] The present invention provides a method for verifying the rock-embedded stability of supporting piles for a rigid-flexible composite foundation pit from a second aspect. The method includes: establishing a model of the relative position relationship between the foundation pit position and the stratum based on geological parameters related to the foundation pit position, and setting an embedding depth parameter and a design width parameter of the rock shoulder; in the embedded pile stage, calculating a critical rock-embedded depth parameter based on a first active soil parameter on the outside of the foundation pit above the embedded rock surface, a rock mass horizontal resistance resultant force parameter provided by the rock mass below the embedded rock surface, and a second distance parameter from the sixth support to the pile bottom; in the hanging pile stage, calculating a critical rock shoulder width parameter based on a second active soil parameter on the outside of the foundation pit below the second support and a fourth distance parameter from the second support to the fourth support; judging whether the embedding depth parameter and the design width parameter of the rock shoulder meet the stability verification conditions according to the first mechanical model and the second mechanical model.

[0017] In the prior art, the structural calculation method for hanging piles still follows the calculation method for foundation pit retaining structures in traditional soft soil areas, and the supporting pile structure is calculated as an embedded pile without considering the structural calculation of the hanging piles after the foundation pit is excavated below the pile bottom, nor the stratigraphic differences between the upper soil and the lower rock. The traditional calculation method for active earth pressure and passive earth pressure is based on the Rankine earth pressure theory. The Rankine earth pressure theory is more in line with the characteristics of soft soil. If the Rankine earth pressure is used to calculate the embedded rock part of the supporting pile, some problems will arise. In view of the defects of the prior art, the present invention distinguishes between the embedded pile stage and the hanging pile stage, and proposes a calculation method and a verification method for the critical embedded rock depth and the critical rock shoulder width. The verification method of the present invention provides important guidance for the design of the supporting structure, and is more conducive to the stability of the supporting structure design and the safety of construction.

[0018] According to a preferred embodiment, the method further includes: when the embedding depth parameter does not meet the conditions of the first mechanical model, increasing the embedding depth; when the design width parameter of the rock shoulder does not meet the conditions of the second mechanical model, increasing the design width of the rock shoulder. On the basis of proposing a calculation method for the critical rock embedding depth and the critical rock shoulder width, the present invention can also give clear guiding suggestions and provide reliable adjustment suggestions for construction personnel or designers of the support structure.

[0019] According to a preferred embodiment, the method further comprises: selecting a minimum rock-embedded depth value that conforms to the first mechanical model as a critical rock-embedded depth parameter; selecting a minimum rock shoulder width value that conforms to the second mechanical model as a critical rock shoulder width parameter; the first mechanical model is: E p1 h p1 +T c1 (h T1 +h d )-K e E a1 h a1 ≥0; the second mechanical model is: E p2 hp2 ≥K T E a2 h a2 ; E p1 Indicates the horizontal resistance parameter of rock mass; h a1 Indicates the first distance parameter from the fifth support point to the pile bottom; h p1 Indicates the second distance parameter from the sixth support point to the pile bottom; T c1 h represents the axial force parameter of the upper support point during the pile embedding stage; T1 Indicates the vertical distance from the first support point to the excavation surface of the foundation pit; h d represents the critical rock-embedded depth parameter; K e E represents the safety factor of rock-embedded stability; a1 Represents active soil resistance parameter; E P2 h is the parameter of the resultant horizontal resistance of the rock shoulder; p2 K represents the fourth distance parameter from the second fulcrum to the fourth fulcrum; T Indicates the stability safety factor of the kicking foot; E a2 It represents the active earth pressure parameter outside the foundation pit below the second support point; h a2 Represents the third distance parameter from the second fulcrum to the third fulcrum.

[0020] Considering two different stability failure modes in the embedded pile stage and the hanging pile stage, the present invention proposes a first mechanical model and a second mechanical model, i.e., two limit equilibrium equations, so as to determine two design variables, namely, a critical rock embedded depth and a critical rock shoulder width, which can not only perform stability verification, but also provide effective guidance for the support structure based on the verification results. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a calculation flow chart of the rock-embedded stability calculation system of the support pile provided by the present invention;

[0022] Figure 2 It is a construction flow chart of the rigid-flexible composite foundation pit provided by the present invention;

[0023] Figure 3 It is the classification value diagram of the geological strength factor GSI of the rock mass in the rock-embedded section;

[0024] Figure 4 It is a schematic diagram of the first mechanical model for checking the stability of embedded rock in the embedded pile stage;

[0025] Figure 5 It is a schematic diagram of the second mechanical model for checking the rock-embedded stability at the hanging pile stage;

[0026] Figure 6 It is a schematic diagram of the stratum conditions of the upper support piles of one of the rigid-flexible composite support systems provided by the present invention.

[0027] Reference numerals list

[0028] 100: processor; 200: information interaction component; 300: support pile; 310: first support point; 320: second support point; 330: third support point; 340: fourth support point; 350: fifth support point; 360: sixth support point; 370: pile bottom; 400: rock-embedded surface; 500: rock shoulder; 600: formation condition; 610: miscellaneous fill soil; 620: strongly weathered granite; 630: moderately weathered granite. DETAILED DESCRIPTION

[0029] The following is a detailed description with reference to the accompanying drawings.

[0030] The support pile 300 is a pile that mainly bears lateral thrust. The support pile 300 is generally used for foundation pit support, slope support and landslide control, and bears horizontal soil pressure or landslide thrust. The support pile 300 generally requires higher reinforcement than the foundation pile that bears vertical force, and is often used together with anchor rods (cables) (pile anchor structure).

[0031] Different from the concept of hanging piles in the field of traditional construction technology, the "hanging piles" in the present invention refer to a kind of support pile 300 in the foundation pit project, where the pile bottom 370 of the support pile 300 is above the bottom of the foundation pit and the pile body is completely exposed.

[0032] Hoek-Brown strength criterion: The Hoek-Brown strength criterion is an empirical formula used to predict rock failure.

[0033] The first fulcrum 310: Because the hanging piles are usually shorter than the depth of the foundation pit, it is assumed here that the hanging piles are only supported by two supports (or anchor rods). The first fulcrum 310 refers to the point of action of the first support (or anchor rod) from top to bottom in the vertical direction on the supporting pile 300.

[0034] Second fulcrum 320: Because the hanging piles are usually shorter than the depth of the foundation pit, it is assumed here that the hanging piles are only supported by two supports (or anchor rods). The second fulcrum 320 refers to the point of action of the second support (or anchor rod) from top to bottom in the vertical direction on the supporting pile 300.

[0035] The third supporting point 330 is the point where the active earth pressure outside the foundation pit acts on the supporting pile 300.

[0036] The fourth supporting point 340 is the point where the resultant horizontal resistance of the rock shoulder acts on the supporting pile 300 .

[0037] The fifth supporting point 350 is the point where the active soil resistance acts on the supporting pile 300 .

[0038] Sixth supporting point 360: the point where the resultant force of the rock mass horizontal resistance provided by the rock mass below the rock-embedded surface 400 acts on the supporting pile 300.

[0039] Rock embedding surface 400: refers to the top surface of the rock mass after the first excavation of the foundation pit to the rock layer during the pile embedding stage, i.e. Figure 2 The location of the foundation pit excavation in Working Conditions 3, 4, and 5.

[0040] Rock shoulder 500: refers to the part of rock mass left after the secondary excavation of the internal rock foundation pit in the hanging pile stage to provide horizontal resistance to the supporting piles 300. This part of the remaining rock mass is called rock shoulder.

[0041] The present invention provides a system and method for checking the rock-embedded stability of supporting piles for rigid-flexible composite foundation pits, which can also be a system and method for checking the rock-embedded stability of supporting piles for rigid-flexible composite foundation pit support system, and can also be a verification device and method for the support stability of rigid-flexible composite foundation pits. The present invention can also provide a terminal for analyzing the support stability of rigid-flexible composite foundation pits. The present invention can also provide a storage medium for analyzing the support stability of rigid-flexible composite foundation pits, in which a coding program for checking the rock-embedded stability of supporting piles for rigid-flexible composite foundation pits is stored.

[0042] The present invention provides a processor 100, in which a coding program of a method for verifying the rock-embedded stability of supporting piles for a rigid-flexible composite foundation pit is provided, and the method for verifying the rock-embedded stability of supporting piles for a rigid-flexible composite foundation pit of the present invention can be executed. The processor 100 of the method for verifying the rock-embedded stability of supporting piles for a rigid-flexible composite foundation pit of the present invention can be a CPU or a dedicated integrated chip, and can be set in a computer, a portable terminal or other device. Portable terminals are, for example, terminal devices such as tablet computers, smart phones, smart watches, and smart glasses. The processor 100 can also be connected to an information interaction component 200 in a wired or wireless manner. The information interaction component 200 is used to input various geometric parameters of the foundation pit, and can also be used to output or display processing information of the processor 100. The information interaction component 200 can be hardware such as a keyboard, a mouse, and a display.

[0043] The processor 100 may also be a server or a cloud server, which provides a remote terminal with a service of a rock-embedded stability verification algorithm for support piles in a rigid-flexible composite foundation pit in a wired or wireless manner.

[0044] The present invention improves the calculation method of the horizontal resistance provided by the rock mass below the rock-embedded surface 400 in the embedded pile stage by using the Hoek-Brown strength criterion (here, the horizontal resistance can be understood as the combined effect of the active earth pressure and the passive earth pressure of the rock-embedded section), and divides the calculation of the supporting piles 300 into the embedded pile stage and the hanging pile stage. In the embedded pile stage, the critical rock-embedded depth of the supporting piles 300 is calculated according to the foundation pit stability requirements, and according to the minimum rock-embedded depth calculated in the embedded pile stage, the critical rock shoulder width is calculated by the kicking stability in the hanging pile stage.

[0045] The present invention has conducted a large number of numerical simulation tests on the mechanical behavior of the whole process of supporting pile construction of the rigid-flexible composite foundation pit support system. According to the numerical results, above the rock-embedded surface 400, the outer soil pressure action point of the supporting pile 300 is basically located between the active soil pressure action point (i.e., the third support point 330) and the static soil pressure action point. Below the rock-embedded surface 400, due to the good properties of the underlying bedrock and the presence of rock mass inside and outside the supporting pile 300, the horizontal displacement of the pile body is greater than the displacement of the rock mass, and the hanging pile is very likely to have been separated from the medium-weathered granite 630 or relaxed, that is, a gap has been generated with the rock mass, so the outer active soil pressure of the supporting pile 300 at the soil-rock interface is zero. The passive soil pressure below the rock-embedded surface 400 is quite different from the Rankine passive soil pressure in terms of distribution form and value. The numerical simulation results show that the soil pressure inside the rock-embedded surface 400 is the largest, and decreases with the depth of the supporting pile 300 into the rock.

[0046] The present invention believes through the above numerical simulation test analysis that the mechanical behavior of the upper soil and the lower rock mass has obvious differences. The traditional Rankine earth pressure theory is based on the Mohr-Coulomb strength criterion, which assumes that the soil is a continuous and uniform material, and shear stress is the fundamental cause of material damage. For the rock mass, the rock mass is composed of rock blocks and structural surfaces. The strength of the rock mass is affected and controlled by the rock mass structural surface to a certain extent. If the Rankine earth pressure theory is continued to be applied to the rock mass, it will be out of touch with the actual situation. Therefore, the present invention applies the Hoek-Brown strength criterion, which is widely used internationally, to the horizontal resistance of the rock mass of the embedded rock part of the support pile 300. Studies have shown that the Hoek-Brown strength criterion more comprehensively reflects the influence of rock mass structure and other characteristics on rock mass strength. It is the most developed method. It reflects the inherent characteristics and nonlinear failure characteristics of the rock mass, as well as the influence of rock strength, number of structural surface groups, excavation disturbance, and rock mass crushing degree on strength.

[0047] Example 1

[0048] The following assumptions are followed in the calculation method and model derivation of the rock-embedded stability of the supporting piles of the rigid-flexible composite foundation pit support system proposed in this patent:

[0049] (1) This embodiment aims to provide a calculation method. To make the calculation process relatively clear, a construction process of a rigid-flexible composite support system for a simple soil-rock foundation pit is considered here. Figure 2 shown. Figure 2 Figure 1 shows five construction conditions, from working condition 1 to working condition 5. Working condition 1 and working condition 2 can be considered that the foundation pit has not yet been excavated to the rock layer, and the support piles 300 are in the soft soil foundation pit embedded pile stage. Working condition 3 and working condition 4 can be considered that the foundation pit is excavated below the rock embedded surface 400, and the support piles 300 are in the soil-rock foundation pit embedded pile stage. Working condition 5 can be considered that the foundation pit continues to be excavated downward after reserving the rock shoulder 500, and the support piles 300 are in the soil-rock foundation pit hanging pile stage.

[0050] (2) The earth pressure exerted by the rock mass above 400° of the embedded rock surface on the supporting piles 300° is calculated according to the Rankine active earth pressure theory.

[0051] (3) Below the rock embedding surface of 400, considering the difference between soil and rock, the passive horizontal resistance of rock to supporting piles of 300 is calculated by adopting the Hoek-Brown strength criterion which takes into account factors such as rock joints and excavation disturbance, and the distribution of passive earth pressure adopts an inverted triangle distribution.

[0052] (4) For the rock embedding depth of the support pile 300, the support structure is designed according to the most unfavorable effect condition. In the construction process considered by the present invention, the most unfavorable effect condition in the pile embedding stage is condition 3. At this time, the foundation pit is excavated below the soil-rock interface, and the bottom row of anchor cables / supports have not yet been constructed. If the rock embedding depth is not enough, damage is likely to occur. The damage mode mainly considers the rotation and displacement of the support pile 300 around the pile bottom 370.

[0053] (5) The design problem of the critical rock shoulder width of the support pile 300 is mainly reflected in working condition 5. Due to the excavation of the "inner pit", only the rocks within the rock shoulder width have a restraining effect on the rock-embedded section of the support pile 300, so the rock shoulder 500 is prone to danger due to insufficient strength. In the calculation of the critical rock shoulder width, the kicking stability is mainly considered. When the rock-embedded section is subject to limited restraint, the upper displacement of the support pile 300 is very small, but the bottom of the support pile 300 will produce a large positive displacement, which is manifested as rotation around the anchor cable or support support point.

[0054] The rock-embedded stability calculation system for supporting piles of a rigid-flexible composite foundation pit of the present invention may include one or more processors 100. The processor 100 is configured to execute the rock-embedded stability calculation method for supporting piles of a rigid-flexible composite foundation pit of the present invention. The processor 100 is a CPU, a dedicated integrated chip, and a server provided with a coding program for the rock-embedded stability calculation method for supporting piles.

[0055] The steps of the rock-embedded stability calculation method for supporting piles used in rigid-flexible composite foundation pits include:

[0056] S1: A model of the relative position relationship between the foundation pit position and the stratum is established based on geological parameters related to the foundation pit position, and an embedding depth parameter and a design width parameter of the rock shoulder 500 are set.

[0057] Obtain basic geological data of the foundation pit range and establish a relative position model between the foundation pit and the strata. Clarify the recommended geotechnical parameter values ​​of each stratum and the geometric parameters of the foundation pit and its support system in the environment, especially the design embedding depth h of the support pile 300 and the design width B of the rock shoulder 500.

[0058] S2: In the pile embedding stage, the critical rock embedding depth parameter is calculated based on the first active soil parameter outside the foundation pit above 400° of the rock embedding surface and the rock mass horizontal resistance resultant force parameter provided by the rock mass below 400° of the rock embedding surface.

[0059] S21: Calculate the active earth pressure parameter p on the outside of the foundation pit above the rock surface ak .

[0060] For soil and water separation,

[0061] For water-soil balanced strata or strata above the groundwater level,

[0062] where σ ak is the vertical stress at the calculation point, is the friction angle of the rock and soil at the calculation point.

[0063] S22: Calculate the active soil resistance parameter E on the outside of the foundation pit above the rock surface a1 and a first distance parameter h from the fifth support point 350 to the pile bottom 370 a1 Active earth resistance refers to the resultant force of active earth pressure above the rock surface, which is a horizontal force, h a1 It is the vertical distance from the fifth supporting point 350 to the pile bottom 370.

[0064] Active soil resistance parameter E a1 is the resultant of active earth pressure.

[0065] Active soil resistance parameter E a1 It is based on the active earth pressure parameter p ak The first distance parameter h is obtained by integration. a1 It is determined based on the law of resultant moment in mechanics.

[0066] S23: Calculate the ultimate resistance parameter P of the pile side inside the foundation pit below the rock surface according to the Hoek-Brown strength criterion L .

[0067] S231: According to the rock type of the rock-embedded section, find its Hoek-Brown constant m through Table 1 i .

[0068] Table 1 Hoek-Brown constants determined by rock type

[0069]

[0070] The values ​​in Table 1 represent the Hoek-Brown constant m i .

[0071] S232: According to Figure 3 The graded value diagram of the geological strength factor GSI of the rock mass in the rock-embedded section shown in the figure is used to find the value of the geological strength factor GSI of the rock mass in the rock-embedded section.

[0072] S233: Obtain the disturbance coefficient D of the rock mass subjected to external loads such as excavation or blasting. The disturbance coefficient D is between 0 and 1, where 0 indicates no disturbance and 1 indicates severe disturbance. There are two ways to obtain the disturbance coefficient D. One is to take the value based on experience, which can be taken according to Table 2; the other is to estimate it according to the measured data of previous excavation projects as follows:

[0073]

[0074] Where V UP is the average longitudinal wave velocity of the undisturbed rock mass, V P It is the average longitudinal wave velocity of the rock mass after disturbance by excavation blasting.

[0075] Table 2 Disturbance degree coefficient D value table

[0076]

[0077] S234: Calculate a second distance parameter from the sixth supporting point 360 provided by the rock mass below the rock embedded surface 400 to the pile bottom 370 in the pile embedding stage.

[0078] The Hoek-Brown constant m obtained in steps S231, S232, and S233 i , GSI coefficient D value is used to calculate the horizontal resistance provided by the rock mass below 400° of the rock-embedded surface:

[0079]

[0080] in:

[0081]

[0082]

[0083]

[0084] γ is the weight of the rock mass, z is the depth of the excavation point below the top surface of the rock mass, and f rc is the uniaxial compressive strength of the intact rock specimen.

[0085] according to Figure 4 It can be seen that the horizontal resistance inside the foundation pit is distributed in an inverted triangle. Through the integral relationship, it can be seen that the resultant horizontal resistance of the rock mass is Distance p1 is the distance from the center of gravity of the inverted triangle to the pile bottom 370,

[0086] S24: Calculate critical rock-embedded depth parameter h d .

[0087] Assumption (4) shows that the most unfavorable effect condition in the embedded pile stage is condition 3, when the foundation pit is excavated below the soil-rock interface and the bottom row of anchor cables / supports has not yet been constructed. If the embedded rock depth is not enough, failure is likely to occur, and the failure mode mainly considers the rotation and displacement of the support pile 300 around the pile bottom 370.

[0088] Therefore, if Figure 4 As shown in the figure, to ensure the stability of the pile bottom 370, the critical rock embedded depth parameter h d The first model must be met: E p1 h p1 +T c1 (h T1 +h d )-K e E a1 h a1 ≥0;

[0089] (501.57 / 3)*h d ^2-1.25*(20.6077*(5.667+h d )+80.42465*(1.978+h d ))>0;

[0090] h d >2.8627m.

[0091] In order to facilitate the design and construction, h d =3m.

[0092] E p1 Indicates the horizontal resistance parameter of rock mass; k a1 represents the first distance parameter from the fifth supporting point 350 to the pile bottom 370; h p1 represents the second distance parameter from the sixth supporting point 360 to the pile bottom 370; T c1 h represents the axial force parameter of the upper support point during the pile embedding stage; T1Indicates the vertical distance from the first support point 310 to the excavation surface of the foundation pit; h d represents the critical rock-embedded depth parameter; K e E represents the safety factor of rock-embedded stability; a1 Represents the active soil resistance parameter.

[0093] The minimum rock-embedded depth value that conforms to the first mechanical model is selected as the critical rock-embedded depth parameter.

[0094] S3: In the hanging pile stage, Figure 5 As shown, the critical rock shoulder width parameter is calculated based on the second active soil parameter outside the foundation pit below the second support point 320 and the distance from the rock shoulder horizontal resistance resultant force to the pile bottom 370.

[0095] S31: Calculate the horizontal resistance curve of the rock shoulder 500 pairs of piles. The horizontal resistance curve of the rock shoulder 500 pairs of piles is as follows: Figure 5 As shown, it is distributed in a triangle, with the rock embedded surface 400 as the coordinate origin, then the horizontal resistance curve equation of the hanging pile stage is:

[0096]

[0097] F x =(24.5×tan 55°×h)·B min 0≤h≤3m.

[0098] γ is the bulk density of the rock shoulder 500, h is the buried depth of the calculation point, is the friction angle of the shoulder 500, c is the cohesion of the shoulder 500, B min is the critical shoulder width.

[0099] S32: Calculation of the horizontal resistance parameter E of the rock shoulder P2 .

[0100]

[0101] Calculate the fourth distance parameter h from the second support point 320 to the fourth support point 340 p2 .

[0102] S33: Calculate the active earth pressure force parameter E outside the foundation pit below the second support point 320 a2 .

[0103] A third distance parameter from the second supporting point 320 to a third supporting point 330 therebelow is calculated.

[0104] Active earth pressure resultant parameter E a2 It is based on the active earth pressure parameter p ak The third distance parameter h is obtained by integration. a2 It is determined based on the law of resultant moment in mechanics.

[0105] S34: Calculation of critical shoulder width B min .

[0106] According to assumption (5) and Figure 2 It can be seen that the most unfavorable working condition in the hanging pile stage is working condition 5, considering the working condition that the kicking foot rotates around the anchor cable or the supporting fulcrum. There is a second mechanical model such as Figure 5 As shown, to ensure the stability of the pile bottom 370, the critical rock shoulder width B min Need to meet:

[0107] E P2 h p2 ≥K T E a2 h a2 ;

[0108]

[0109] Where K T K is the safety factor of the skirting stability. For the first, second and third level foundation pits, T Take 1.25, 1.2, and 1.15 respectively.

[0110] E P2 h is the parameter of the resultant horizontal resistance of the rock shoulder; p2 K represents a fourth distance parameter from the second supporting point 320 to the fourth supporting point 340; T Indicates the stability safety factor of the kicking foot; E a2 It represents the active earth pressure parameter outside the foundation pit below the second support point 320; h a2 The third distance parameter from the second supporting point 320 to the third supporting point 330 is represented.

[0111] As shown above, the minimum rock shoulder width value that conforms to the second mechanical model is selected as the critical rock shoulder width parameter.

[0112] S4: Figure 1 As shown, it is determined whether the embedding depth parameter and the design width parameter of the rock shoulder 500 meet the stability verification conditions according to the first mechanical model and the second mechanical model.

[0113] S41: When the embedding depth parameter does not satisfy the condition of the first mechanical model, the information generated by the processor 100 includes: increasing the embedding depth.

[0114] S42: When the design width parameter of the shoulder 500 does not satisfy the condition of the second mechanical model, the information generated by the processor 100 includes: increasing the design width of the shoulder 500 .

[0115] Taking into account the stratum differences between the upper soil and the lower rock, the present invention applies the Hoek-Brown strength criterion, which is widely used internationally, to the calculation of the horizontal resistance of the rock-embedded part of the support pile. At the same time, it takes into account the problem that when the foundation pit is excavated to below 370° of the pile bottom and the support pile 300 enters the hanging pile stage, the horizontal resistance provided by the rock mass of the rock-embedded section to the hanging pile will be greatly reduced. By analyzing the two different stability failure modes of the embedded pile stage and the hanging pile stage, two limit equilibrium equations are obtained, thereby providing a method that can help construction personnel determine the two key design parameters of the critical rock-embedded depth and the critical rock shoulder width, which can help construction personnel verify the rock-embedded stability of the support piles of the rigid-flexible composite foundation pit support system.

[0116] Example 2

[0117] This embodiment is an example of the rock-embedded stability verification method of the support piles for a rigid-flexible composite foundation pit of the present invention.

[0118] S1: A model of the relative position relationship between the foundation pit position and the stratum is established based on geological parameters related to the foundation pit position, and an embedding depth parameter and a design width parameter of the rock shoulder 500 are set.

[0119] Figure 6 Schematic diagram of the ground conditions 600 of the upper support piles 300 of the rigid-flexible composite support system of a certain level of foundation pit. Figure 6 In the embodiment, the support pile 300 is embedded in the medium weathered granite 630. The elastic modulus of the medium weathered granite 630 is 5000Mpa, the thickness of the miscellaneous fill 610 is 2m, and the gravity γ1 is 17.5kN / m 3 , friction angle The thickness of the strongly weathered granite 620 is 5m, and its gravity is γ2 = 23.5kN / m 3 , friction angle The specific gravity of medium weathered granite 630 is γ3 = 24.5 kN / m 3 , friction angle Uniaxial compressive strength of intact rock specimen f rc =30MPa, Hoek-Brown constant m i =30, geological intensity factor GSI = 40, disturbance coefficient D = 0.5,

[0120] S2 pile embedment stage:

[0121] S21: Calculate the active earth pressure parameter p on the outside of the foundation pit above the rock surface ak

[0122] For soil and water separation, u a Indicates the pressure on the outside of the supporting structure.

[0123] For water-soil balanced strata or strata above the groundwater level,

[0124] σ ak is the vertical stress at the calculation point, is the friction angle of the rock and soil at the calculation point.

[0125] Then the active earth pressure at point A is 0.

[0126] The active earth pressure at point B (miscellaneous fill 610) is

[0127] p ak =17.5×2×tan 2 (45°-15° / 2)=20.6077kN / m.

[0128] The active earth pressure at point B (strong weathering) is

[0129] p ak =17.5×2×tan 2 (45°-45° / 2)=6.0050kN / m.

[0130] The active earth pressure at point C (strong weathering) is

[0131] p ak =(17.5×2+23.5×5)×tan 2 (45°-45° / 2)=26.16486kN / m.

[0132] S22: Calculate the resultant active earth pressure on the outside of the foundation pit above the rock surface, i.e., the active earth resistance E a1 and a first distance h from the fifth support point 350 to the pile bottom 370 a1 .

[0133] Active soil resistance of section AB:

[0134]

[0135] The first distance h from the fifth support point 350 of the AB segment to the pile bottom 370 a1 :

[0136]

[0137] Active soil resistance of BC section:

[0138]

[0139] The first distance h from the fifth supporting point 350 of the BC segment to the pile bottom 370 a1 :

[0140] h a1=5×(2×6.0050+26.16486) / 3(6.0050+26.16486)+h d =1.978+h d .

[0141] S23: Calculate the ultimate resistance P of the pile side below the rock surface and inside the foundation pit according to the Hoek-Brown strength criterion L , specifically, comprising the following steps:

[0142] S231: According to the rock type of the rock-embedded section, find its Hoek-Brown constant m through Table 1 i .

[0143] The embedded rock section is moderately weathered granodiorite, and the m i =30.

[0144] S232: According to Figure 3 Find the geological strength factor GSI value of the rock mass in the rock-embedded section.

[0145] The rock in the embedded section is moderately weathered rock mass, containing angular block folds formed by many discontinuous sets, with GSI = 40.

[0146] S233: Obtain the disturbance degree coefficient D of the rock mass subjected to external loads such as excavation or blasting.

[0147] According to previous engineering experience, D=0.5.

[0148] S234: The Hoek-Brown constant m obtained according to steps S231, S232, and S233 i , GSI coefficient D value is used to calculate the horizontal resistance provided by the rock mass below 400° of the rock-embedded surface:

[0149] in:

[0150]

[0151]

[0152]

[0153]

[0154] S235: Calculate critical rock-embedded depth h d .

[0155] like Figure 4 As shown in the first mechanical model, in order to ensure the stability of the pile bottom 370, the critical rock embedding depth h d Need to meet:

[0156] E p1h p1 +T c1 (h T1 +h d )-K e E a1 h a1 ≥0;

[0157] (501.57 / 3)*h d ^2-1.25*(20.6077*(5.667+h d )+80.42465*(1.978+h d ))>0;

[0158] h d >2.8627m;

[0159] In order to facilitate the design and construction, h d =3m.

[0160] S3: Hanging pile stage.

[0161] S31: Calculate the horizontal resistance curve of the rock shoulder 500 pairs of piles. The horizontal resistance curve of the rock shoulder 500 pairs of piles is as follows: Figure 4 As shown, it is distributed in a regular triangle. With the rock-embedded surface 400 as the coordinate origin, the horizontal resistance curve equation of the hanging pile stage is:

[0162]

[0163] F x =(24.5×tan 55°×h)·B min 0≤h≤3m.

[0164] S32: Calculation of the horizontal resistance force E of the rock shoulder P2 :

[0165]

[0166] S33: Calculate the active earth pressure E outside the foundation pit below the second support point 320 a2 , the calculation method is the same as steps S21 and S22.

[0167] Active soil resistance E of CD segment a2 :

[0168] E a2 =(17.5×2+23.5×5)×tan 2 (45°-55° / 2)×3=45.48kN:

[0169] The third distance k from the second supporting point 320 to the third supporting point 330 of the CD segment a2 :

[0170]

[0171] S34: Calculation of critical shoulder width B min .

[0172] like Figure 5 As shown in the second mechanical model, in order to ensure the stability of the pile bottom 370, the critical rock shoulder width B min Need to meet:

[0173] E P2 h p2 ≥K T E a2 h a2 ;

[0174]

[0175] B min ≥0.3m.

[0176] It should be noted that the above-mentioned specific embodiments are exemplary, and those skilled in the art can come up with various solutions inspired by the disclosure of the present invention, and these solutions also belong to the disclosure scope of the present invention and fall within the protection scope of the present invention. Those skilled in the art should understand that the present invention specification and its drawings are illustrative and do not constitute limitations on the claims. The scope of protection of the present invention is defined by the claims and their equivalents. The present invention specification contains multiple inventive concepts, such as "according to a preferred embodiment", which means that the corresponding paragraph discloses an independent concept, and the applicant reserves the right to file a divisional application based on each inventive concept.

Claims

1. A rock-embedded stability calculation system for supporting piles in a rigid-flexible composite foundation pit, comprising a processor (100), characterized in that: The processor (100) is configured to: A model of the relative position relationship between the foundation pit position and the stratum is established based on geological parameters related to the foundation pit position, and an embedding depth parameter and a design width parameter of the rock shoulder (500) are set; In the pile embedding stage, a critical rock embedding depth parameter is calculated based on a first active soil parameter outside the foundation pit above the rock embedding surface (400), a rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock embedding surface (400), and a second distance parameter from the sixth support point (360) to the pile bottom (370): a minimum rock embedding depth value that meets the first mechanical model is selected as the critical rock embedding depth parameter: In the hanging pile stage, a critical rock shoulder width parameter is calculated based on a second active soil parameter outside the foundation pit below the second support point (320) and a fourth distance parameter from the second support point (320) to the fourth support point (340); a minimum rock shoulder width value that meets the second mechanical model is selected as the critical rock shoulder width parameter; Determining whether the embedding depth parameter and the design width parameter of the rock shoulder (500) meet stability verification conditions according to the first mechanical model and the second mechanical model; If the critical rock-embedded depth h d Satisfies the first mechanical model: E p1 h p1 +T c1 (h T1 +h d )-K e E a1 h a1 ≥0, the stability of the pile bottom (370) is guaranteed; If the critical shoulder width B min Requirements: The stability of the pile bottom (370) is ensured. Wherein, the second mechanical model is: P2 h p2 ≥K T E a2 h a2 ; The E p1 Indicates the rock mass horizontal resistance force parameter: a1 The first distance parameter representing the distance from the fifth supporting point (350) to the pile bottom (370): p1 The second distance parameter representing the sixth support point (360) to the pile bottom (370): c1 The h represents the axial force parameter of the upper support point in the embedded pile stage: T1 represents the vertical distance from the first support point (310) to the excavation surface of the foundation pit: d The critical rock-embedded depth parameter: K e Indicates the rock-embedded stability safety factor: E a1 Represents the active soil resistance parameter: P2 The h represents the horizontal resistance parameter of the rock shoulder: p2 The fourth distance parameter representing the distance from the second support point (320) to the fourth support point (340): T Indicates the skirting stability safety factor: E a2 represents the active earth pressure parameter outside the foundation pit below the second support point (320): a2 represents the third distance parameter from the second support point (320) to the third support point (330): γ is the bulk density of the rock shoulder (500), is the friction angle of the rock shoulder (500), and c is the cohesion of the rock shoulder (500).

2. The rock-embedded stability calculation system for supporting piles of a rigid-flexible composite foundation pit according to claim 1 is characterized in that: The processor (100) calculates the first active soil parameter outside the foundation pit above the rock-embedded surface (400) in a manner comprising: Calculate the active earth pressure parameters outside the foundation pit above the rock surface; Active soil resistance parameters outside the foundation pit above the rock surface and a first distance parameter from the fifth support point (350) to the pile bottom (370) are calculated; the fifth support point (350) is the action point of the active soil resistance on the support pile (300).

3. The rock-embedded stability calculation system for supporting piles used in rigid-flexible composite foundation pits according to claim 1 or 2, characterized in that: The processor (100) calculates the rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock-embedded surface (400) in a manner including: The ultimate resistance parameters of the pile side inside the foundation pit below the rock surface are calculated according to the Hoek-Brown strength criterion; The rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock embedding surface (400) during the pile embedding stage and the second distance parameter from the sixth support point (360) to the pile bottom (370) are calculated. The sixth support point (360) is the point of action of the rock mass horizontal resistance resultant force on the support pile (300).

4. The rock-embedded stability calculation system for supporting piles of a rigid-flexible composite foundation pit according to claim 3 is characterized in that: The processor (100) calculates the second active soil parameter outside the foundation pit below the second support point (320) in a manner including: Calculate the active earth pressure resultant parameters outside the foundation pit below the second support point (320); A third distance parameter from the second supporting point (320) to the third supporting point (330) is calculated; the third supporting point (330) is the point of action of the active earth pressure resultant of the outer layer of the foundation pit below the second supporting point (320) on the supporting pile (300).

5. The rock-embedded stability calculation system for supporting piles of rigid-flexible composite foundation pit according to claim 3 is characterized in that: The processor (100) is also configured to: When the embedding depth parameter does not satisfy the condition of the first mechanical model, the information generated by the processor (100) includes: increasing the embedding depth; When the design width parameter of the shoulder (500) does not satisfy the conditions of the second mechanical model, the information generated by the processor (100) includes: increasing the design width of the shoulder (500).

6. A method for calculating the stability of embedded rock of supporting piles for rigid-flexible composite foundation pits, characterized in that: The method comprises: Based on the geological parameters related to the foundation pit location, a model of the relative position relationship between the foundation pit location and the stratum is established, and the embedding depth parameters and the design width parameters of the rock shoulder (500) are set: In the pile embedding stage, the critical rock embedding depth parameter is calculated based on the first active soil parameter outside the foundation pit above the rock embedding surface (400), the rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock embedding surface (400), and the second distance parameter from the sixth support point (360) to the pile bottom (370): In the hanging pile stage, the critical rock shoulder width parameter is calculated based on the second active soil parameter outside the foundation pit below the second support point (320) and the fourth distance parameter from the second support point (320) to the fourth support point (340): Judging whether the embedding depth parameter and the design width parameter of the rock shoulder (500) meet the stability verification condition according to the first mechanical model and the second mechanical model: the method further comprises: Selecting the minimum rock-embedded depth value that meets the first mechanical model as the critical rock-embedded depth parameter; Select the minimum rock shoulder width value that meets the second mechanical model as the critical rock shoulder width parameter; If the critical rock-embedded depth h d Satisfies the first mechanical model: E p1 h p1 +T c1 (h T1 +h d )-K e E a1 h a1 ≥0, the stability of the pile bottom (370) is guaranteed; If the critical shoulder width B min Requirements: The stability of the pile bottom (370) is ensured. Wherein, the second mechanical model is: P2 h p2 ≥K T E a2 h a2 ; The E p1 represents the rock mass horizontal resistance resultant force parameter; a1 represents the first distance parameter from the fifth supporting point (350) to the pile bottom (370); the h p1 represents a second distance parameter from the sixth supporting point (360) to the pile bottom (370); the T c1 represents the axial force parameter of the upper support point in the embedded pile stage; T1 represents the vertical distance from the first support point (310) to the excavation surface of the foundation pit; the h d represents the critical rock-embedded depth parameter; e represents the rock-embedded stability safety factor; the E a1 represents the active soil resistance parameter; P2 represents the horizontal resistance parameter of the rock shoulder; p2 represents a fourth distance parameter from the second supporting point (320) to the fourth supporting point (340); the K T Indicates the safety factor of kicking stability; a2 represents the active earth pressure parameter outside the foundation pit below the second support point (320); the h a2 represents the third distance parameter from the second support point (320) to the third support point (330); γ ​​is the bulk density of the rock shoulder (500), is the friction angle of the rock shoulder (500), and c is the cohesion of the rock shoulder (500).

7. The rock-embedded stability calculation method for supporting piles used in a rigid-flexible composite foundation pit according to claim 6 is characterized in that: The method further comprises: When the embedding depth parameter does not satisfy the condition of the first mechanical model, increasing the embedding depth; When the design width parameter of the rock shoulder (500) does not satisfy the conditions of the second mechanical model, the design width of the rock shoulder (500) is increased.

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