Processor for calculating critical data of rock socketed support pile and calculation method thereof

Abstract

The invention relates to a processor and a calculation method for calculating critical data of support pile socketed rock, and the processor is configured as follows: in a pile build-in stage, calculating a critical socketed rock depth parameter based on a first active soil parameter on the outer side of a foundation pit above a socketed rock surface and a rock mass horizontal resistance resultant force parameter provided by a rock mass below the socketed rock surface; selecting a minimum rock-socketed depth value conforming to the first mechanical model as a critical rock-socketed depth parameter; the first mechanical model is as follows: Ep1hp1 + Tc1 (hT1 + hd)-KeEa1ha1 is greater than or equal to 0; ep1 represents a rock mass horizontal resistance resultant force parameter; ha1 represents a first distance parameter from the fifth fulcrum to the pile bottom; hp1 represents a second distance parameter from the sixth fulcrum to the pile bottom; tc1 represents an upper-layer fulcrum axial force parameter in the pile embedding and fixing stage; hT1 represents the vertical distance from the first fulcrum to the excavation face of the foundation pit; hd represents a critical rock-socketed depth parameter; ke represents the rock-socketed stability safety coefficient; ea1 represents an active soil resistance parameter. The critical rock-socketed depth obtained according to the limit condition and the first mechanical model is the minimum rock-socketed depth, and a good supporting effect is achieved.

Description

[0001] The original basis of this divisional application is the patent application with application number 202410618741X, application date 2024.5.17, and invention name “System and method for verifying the rock-embedded stability of support piles for rigid-flexible composite foundation pits”. Technical Field

[0002] The present invention relates to the technical field of geotechnical engineering, and in particular to a processor and a calculation method thereof for calculating critical data of rock-embedded support piles. Background Art

[0003] With the development of urban rail transit construction in my country, complex and differentiated engineering geological environments have emerged, presenting new challenges and opportunities for urban rail transit project construction. Soil-rock composite strata are a typical complex engineering geological environment. The physical and mechanical properties of the upper soil layer and the lower rock layer vary significantly, such as strength, stiffness, permeability, and stability. Consequently, excavation methods and the difficulty of pile construction vary greatly, resulting in the strata being "soft on top and hard on the bottom." Open-cut is the most common and economical method for constructing subway stations and is widely used in the urban rail transit construction industry. In cities with upper soil and lower rock, a rigid-flexible composite support system (rigid on top and flexible on the bottom) is required to ensure the safety of deep open-cut foundation pits. Currently, partially rock-embedded "hanging piles" are widely used as foundation pit support structures in the upper soft soil strata of cities with soil-rock composite strata. This foundation pit support system, combining upper "hanging piles" with lower shotcrete support, is known as a rigid-flexible composite foundation pit support system.

[0004] "Dangling piles" refer to a type of support pile in foundation pit engineering. They refer 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 the support of deep foundation pit projects in many places, achieving good support effects and significant benefits. However, theoretical research on sling piles lags far behind engineering, and structural calculations still follow the traditional calculation method for foundation pit retaining structures in soft soil areas, which leads 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. The horizontal resistance provided by the rock mass in the embedded 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 stratum 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.

[0005] Therefore, in light of these shortcomings, the present invention, through dedicated research and design, integrating years of experience and achievements in related industries, applies the internationally widely used Hoek-Brown strength criterion to the calculation of the horizontal resistance of the rock-embedded portion of support piles. Through in-depth research on the structural stress characteristics and failure modes throughout the sling pile construction process, a method and system for calculating the rock-embedded depth and reserved rock shoulder width of the upper support piles during the sling pile stage was proposed, forming a guiding method and system for verifying the rock-embedded stability of support piles in rigid-flexible composite foundation pit support systems.

[0006] 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

[0007] 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 stratum 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. 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.

[0008] In response to the deficiencies of the prior art, the present invention provides, from a first aspect, a rock-embedded stability verification system for support piles of rigid-flexible composite foundation pits, comprising 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 outside the foundation pit above the rock-embedded surface, the rock mass horizontal resistance resultant parameter provided by the rock mass below the rock-embedded 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 outside the foundation pit below the second support and the fourth distance parameter from the second support to the fourth support; determine whether the embedding depth parameter and the design width parameter of the rock shoulder meet the stability verification conditions based on the first mechanical model and the second mechanical model. The rock shoulder horizontal resistance resultant can be understood as the combined effect of the active earth pressure and the passive earth pressure of the rock-embedded section.

[0009] The present invention improves the method for calculating 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 support pile calculation into the embedded pile stage and the dangling pile stage. In the embedded pile stage, the critical rock-embedded depth of the support pile is calculated according to the stability requirements of the foundation pit, and the critical rock-embedded depth is obtained according to the calculation in the embedded pile stage. In the dangling 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 in the embedded section to the dangling pile will be greatly reduced when the foundation pit is excavated below the pile bottom and the support pile enters the dangling pile stage. By analyzing the two different stability failure modes in the embedded pile stage and the dangling 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 support piles in the rigid-flexible composite foundation pit support system.

[0010] According to a preferred embodiment, the processor calculates the first active soil parameter outside the foundation pit above the rock surface by: calculating the active earth pressure parameter outside the foundation pit above the rock surface; calculating the active earth 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 being the point of action of the active earth resistance on the support pile. Above the rock surface, the earth pressure action point outside the support pile is substantially between the active earth pressure action point and the static earth pressure action point. Calculating the active earth pressure parameter and the first distance parameter outside the foundation pit above the rock surface facilitates determining the resultant force acting on the portion of the support pile above the rock surface.

[0011] 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 by: calculating the pile side ultimate resistance parameter 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 during the pile-embedded phase and the second distance parameter from the sixth support point to the pile bottom, where the sixth support point is the point of action of the rock mass horizontal resistance resultant force on the support pile. Below the rock-embedded surface, due to the good properties of the underlying bedrock and the presence of rock mass both inside and outside the support pile, the horizontal displacement of the pile is greater than the displacement of the rock mass. The hanging pile is very likely to have detached from the moderately weathered granite or relaxed, i.e., a gap has been created with the rock mass. Therefore, the active earth pressure outside the support pile at the soil-rock interface is zero. The passive earth pressure below the rock-embedded surface differs significantly from the Rankine passive earth pressure in terms of distribution and value. By calculating the resultant force acting on the support pile below the rock-embedded surface and the second distance parameter, the numerical simulation results show that the soil pressure inside the support pile at the rock-embedded surface is the largest and decreases with the depth of the support pile in the rock.

[0012] According to a preferred embodiment, the processor calculates the critical rock-socketed depth parameter in the following manner: selecting the minimum rock-socketed depth value that conforms to the first mechanical model as the critical rock-socketed 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 represents the resultant horizontal resistance parameter of rock mass; h a1 Indicates the first distance parameter from the fifth support point to the pile bottom; h p1 The second distance parameter from the sixth support point to the pile bottom; T c1 represents the axial force parameter of the upper support in the embedded pile stage; h T1 Indicates the vertical distance from the first support point to the excavation surface of the foundation pit; h d represents the critical rock-socketing depth parameter; K e represents the safety factor of rock-embedded stability; E 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 working condition 3 in the embodiment. At this time, 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 rock-embedded depth is not enough, it is easy to cause damage. The failure mode mainly considers the rotation and displacement of the support piles around the pile bottom. The critical rock-embedded depth obtained according to this extreme case and the first mechanical model is the minimum rock-embedded depth. Only a rock-embedded depth greater than the critical rock-embedded depth can achieve a better support effect.

[0013] According to a preferred embodiment, the processor calculates the second active soil parameters outside the foundation pit below the second support point by: calculating the active earth pressure resultant force parameter outside the foundation pit below the second support point; and calculating a third distance parameter from the second support point to a third support point; the third support point being the point of action of the active earth pressure resultant force on the support piles in the outer layer of the foundation pit below the second support point. By calculating the resultant force of the rock mass below the rock embedment surface on the support piles and the third distance parameter, data support can be provided for the calculation of the second mechanical model.

[0014] According to a preferred embodiment, the processor calculates the critical shoulder width parameter in the following manner: 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 Indicates the fourth distance parameter from the second support point to the fourth support point; the fourth support point is the point where the resultant force of the horizontal resistance of the rock shoulder acts on the support 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 The third distance parameter representing the distance from the second fulcrum to the third fulcrum.

[0015] The design issue of the critical rock shoulder width for support piles primarily arises in Working Condition 5 of the embodiment. Due to the excavation of the "inner pit," only the rock within the rock shoulder width constrains the rock-embedded section of the support pile. This section, therefore, is susceptible to danger due to insufficient strength. The calculation of the critical rock shoulder width primarily considers kicker stability. When the rock-embedded section is subject to limited constraints, the upper displacement of the support pile is minimal, but the base of the pile experiences significant positive displacement, manifesting as rotation about the anchor cable or support fulcrum. Therefore, the critical rock-embedded depth parameter derived from the second mechanical model designed in this invention provides construction personnel with highly useful reference information for the rock-embedded stability of support piles.

[0016] According to a preferred embodiment, the processor is further configured to: if the embedment depth parameter does not meet the conditions of the first mechanical model, the processor generates information including: increasing the embedment depth; if the design width parameter of the rock shoulder does not meet the conditions of the second mechanical model, the processor generates information including: increasing the design width of the rock shoulder. The processor of the present invention can use the first and second mechanical models to quickly verify the rock embedment stability of the support piles in the support system of the rigid-flexible composite foundation pit and provide appropriate support recommendations.

[0017] From a second aspect, the present invention provides a method for verifying the rock-embedded stability of support piles for a rigid-flexible composite foundation pit. 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 outside the foundation pit above the rock-embedded surface, a rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock-embedded 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 outside the foundation pit below the second support and a fourth distance parameter from the second support to the fourth support; and judging whether the embedding depth parameter and the design width parameter of the rock shoulder meet the stability verification conditions based on the first mechanical model and the second mechanical model.

[0018] In the prior art, the structural calculation method for hanging piles still follows the traditional calculation method for foundation pit retaining structure in 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 stratum 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, and if the Rankine earth pressure is used to calculate the embedded rock part of the supporting pile, some problems will arise. In response to 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 rock embedded depth and the critical rock shoulder width. The verification method of the present invention provides important guidance for the design of the support structure, and is more conducive to the stability of the support structure design and the safety of construction.

[0019] According to a preferred embodiment, the method further includes: increasing the embedment depth if the embedment depth parameter does not meet the conditions of the first mechanical model; and increasing the design width of the rock shoulder if the design width parameter of the rock shoulder does not meet the conditions of the second mechanical model. Based on the proposed calculation method for the critical rock embedment depth and critical rock shoulder width, the present invention can also provide clear guidance and reliable adjustment suggestions for support structure constructors or designers.

[0020] According to a preferred embodiment, the method further comprises: selecting a minimum rock socket depth value that conforms to the first mechanical model as a critical rock socket 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 represents the resultant horizontal resistance parameter of rock mass; h a1 Indicates the first distance parameter from the fifth support point to the pile bottom; h p1 The second distance parameter from the sixth support point to the pile bottom; T c1 represents the axial force parameter of the upper support in the embedded pile stage; h T1 Indicates the vertical distance from the first support point to the excavation surface of the foundation pit; h d represents the critical rock-socketing depth parameter; K e represents the safety factor of rock-embedded stability; E a1 represents the active soil resistance parameter; E P2 h is the parameter of the resultant horizontal resistance of the rock shoulder; p2 The fourth distance parameter from the second fulcrum to the fourth fulcrum; 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 The third distance parameter representing the distance from the second fulcrum to the third fulcrum.

[0021] Considering the two different stability failure modes in the embedded pile stage and the suspended pile stage, the present invention proposes a first mechanical model and a second mechanical model, i.e., two limit equilibrium equations, to determine the two design variables, the critical rock-embedded depth and the critical rock shoulder width. This allows for stability verification and provides effective guidance for support structures based on the verification results. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a calculation flow chart of the rock-embedded stability calculation system for support piles provided by the present invention;

[0023] Figure 2 This is a construction flow chart of the rigid-flexible composite foundation pit provided by the present invention;

[0024] Figure 3 It is a graded value diagram of the geological strength factor GSI of the rock mass in the rock-embedded section;

[0025] Figure 4 This is a schematic diagram of the first mechanical model for rock-socket stability verification during the pile embedment stage;

[0026] Figure 5 This is a schematic diagram of the second mechanical model for checking the rock-embedded stability at the hanging pile stage;

[0027] 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.

[0028] Reference Signs List

[0029] 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: Stratum condition; 610: Miscellaneous fill; 620: Highly weathered granite; 630: Moderately weathered granite. DETAILED DESCRIPTION

[0030] The following is a detailed description with reference to the accompanying drawings.

[0031] Support piles 300 are primarily designed to withstand lateral thrust. They are commonly used for foundation pit support, slope support, and landslide control, withstanding horizontal soil pressure or landslide thrust. Support piles 300 generally require higher reinforcement than foundation piles, which are designed to withstand vertical forces. They are often used in conjunction with anchor rods (cables) (pile-anchor structures).

[0032] Different from the concept of hanging piles in the traditional construction technology field, the "hanging piles" in the present invention refer to a retaining 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.

[0033] Hoek-Brown strength criterion: The Hoek-Brown strength criterion is an empirical formula used to predict rock failure.

[0034] First fulcrum 310: Because the stilt pile is usually shorter than the depth of the foundation pit, it is assumed here that the stilt pile is 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 support pile 300.

[0035] Second fulcrum 320: Because the sling pile is usually shorter than the depth of the foundation pit, it is assumed here that the sling pile is 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 support pile 300.

[0036] The third supporting point 330 is the point where the active earth pressure outside the foundation pit acts on the supporting pile 300.

[0037] The fourth supporting point 340 is the point where the resultant horizontal resistance of the rock shoulder acts on the supporting pile 300 .

[0038] The fifth supporting point 350 is the point where the active soil resistance acts on the supporting pile 300 .

[0039] Sixth supporting point 360: the point where the resultant horizontal resistance of the rock mass provided by the rock mass below the rock-embedded surface 400 acts on the supporting pile 300.

[0040] 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 embedded pile stage, that is, Figure 2 The location of the foundation pit excavation in working conditions 3, 4 and 5.

[0041] Rock shoulder 500: refers to the rock mass that remains 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 remaining rock mass is called rock shoulder.

[0042] The present invention provides a system and method for verifying the rock-embedded stability of support piles in a rigid-flexible composite foundation pit. It can also be a system and method for verifying the rock-embedded stability of support piles in a rigid-flexible composite foundation pit support system, or a device and method for verifying the support stability of a rigid-flexible composite foundation pit. The present invention can also provide a terminal for analyzing the support stability of a rigid-flexible composite foundation pit. The present invention can also provide a storage medium for analyzing the support stability of a rigid-flexible composite foundation pit, the storage medium storing a coded program for verifying the rock-embedded stability of support piles in a rigid-flexible composite foundation pit.

[0043] The present invention provides a processor 100, which is provided with a coding program for a method for verifying the rock-embedded stability of support piles for a rigid-flexible composite foundation pit, and is capable of executing the method for verifying the rock-embedded stability of support piles for a rigid-flexible composite foundation pit of the present invention. The processor 100 of the method for verifying the rock-embedded stability of support 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, 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 via a wired or wireless method. 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.

[0044] 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 of a rigid-flexible composite foundation pit in a wired or wireless manner.

[0045] The present invention utilizes the Hoek-Brown strength criterion to improve the calculation method for the horizontal resistance provided by the rock mass below the rock-embedded surface 400 during the embedded pile stage (here, horizontal resistance can be understood as the combined effect of the active and passive earth pressures in the rock-embedded section). The calculation of the support piles 300 is divided into the embedded pile stage and the hanging pile stage. During the embedded pile stage, the critical rock-embedded depth of the support piles 300 is calculated according to the foundation pit stability requirements. Based on the minimum rock-embedded depth calculated during the embedded pile stage, the critical rock shoulder width is calculated during the hanging pile stage using the kicker stability calculation.

[0046] The present invention conducted extensive numerical simulations of the mechanical behavior of support piles during the entire construction process of a rigid-flexible composite foundation pit support system. Numerical results show that above the rock-embedded surface 400, the outer earth pressure point of the support pile 300 is essentially located between the active earth pressure point (i.e., the third support point 330) and the static earth pressure point. Below the rock-embedded surface 400, due to the superior properties of the underlying bedrock and the presence of rock mass both inside and outside the support pile 300, the horizontal displacement of the pile is greater than the displacement of the rock mass. The hanging piles are likely to have detached from the moderately weathered granite 630 or become loose, creating a gap with the rock mass. Therefore, the outer active earth pressure of the support pile 300 at the soil-rock interface is zero. The passive earth pressure below the rock-embedded surface 400 differs significantly from the Rankine passive earth pressure in terms of distribution and value. Numerical simulation results show that the earth pressure is greatest inside the rock-embedded surface 400 and decreases with the depth of the support pile 300 into the rock.

[0047] Through the above-mentioned numerical simulation test analysis, the present invention concludes that the mechanical behavior of the upper soil and the lower rock mass differ significantly. 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 that shear stress is the fundamental cause of material failure. Rock mass is composed of rock blocks and structural planes, and its strength is, to a certain extent, influenced and controlled by these structural planes. Continuing to apply the Rankine earth pressure theory to rock mass would be out of touch with reality. Therefore, the present invention applies the internationally widely used Hoek-Brown strength criterion to the horizontal resistance of the rock mass in the embedded rock portion of support pile 300. Research has shown that the Hoek-Brown strength criterion comprehensively reflects the influence of rock mass structural characteristics on rock mass strength and is the most developed method. It reflects the inherent characteristics and nonlinear failure characteristics of rock mass, as well as the influence of rock strength, the number of structural plane groups, excavation disturbance, and the degree of rock mass fragmentation on strength.

[0048] Example 1

[0049] The following assumptions are followed in the calculation method and model derivation for the rock-embedded stability of supporting piles in the rigid-flexible composite foundation pit support system proposed in this patent:

[0050] (1) This embodiment aims to provide a calculation method. To make the calculation process relatively clear, the construction process of a rigid-flexible composite support system for a simple soil-rock foundation pit is considered here. Figure 2 shown. Figure 2 The figure shows five construction conditions, working conditions 1 to 5. Working conditions 1 and 2 represent the foundation pit not yet excavated to the rock layer, at which point the support piles 300 are in the soft soil foundation pit embedded pile stage. Working conditions 3 and 4 represent the foundation pit excavated below the rock embedding surface 400, at which point the support piles 300 are in the soil-rock foundation pit embedded pile stage. Working condition 5 represents the foundation pit excavated after the rock shoulder 500 is reserved and further excavation continues, at which point the support piles 300 are in the soil-rock foundation pit suspended pile stage.

[0051] (2) The earth pressure exerted by the rock mass above 400° of the embedded rock surface on the supporting pile 300° is calculated according to the Rankine active earth pressure theory.

[0052] (3) Below the rock embedment surface of 400, considering the difference between soil and rock, the passive horizontal resistance of rock to support 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.

[0053] (4) With respect to the embedded depth of the support pile 300, the support structure is designed according to the most unfavorable effect condition. In the construction process considered in the present invention, the most unfavorable effect condition in the embedded pile 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 has not yet been constructed. If the embedded 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.

[0054] (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. Therefore, the rock shoulder 500 is prone to danger due to insufficient strength. In the calculation of the critical rock shoulder width, the stability of the kicker is mainly considered. When the restraint effect on the rock-embedded section is limited, 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.

[0055] The system for verifying the rock-embedded stability of supporting piles in a rigid-flexible composite foundation pit of the present invention may include one or more processors 100. Processors 100 are configured to execute the rock-embedded stability verification method for supporting piles in a rigid-flexible composite foundation pit of the present invention. Processor 100 comprises a CPU, a dedicated integrated circuit, and a server equipped with a coding program for the rock-embedded stability verification method for supporting piles.

[0056] The steps of the rock-embedded stability verification method for support piles in rigid-flexible composite foundation pits include:

[0057] S1: Based on 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 embedded depth parameters and design width parameters of the rock shoulder 500 are set.

[0058] Obtain basic geological data for the excavation area and establish a model for the relative position of the excavation and strata. Clarify the recommended geotechnical parameters for each stratum and the geometric parameters of the excavation and its support system within the environment, particularly the design embedment depth h of the support piles 300 and the design width B of the rock shoulder 500.

[0059] S2: During 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 and the rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock embedding surface 400.

[0060] S21: Calculate the active earth pressure parameter p outside the foundation pit above the rock surface ak .

[0061] For soil and water separation,

[0062] For water-soil balanced strata or strata above the groundwater level,

[0063] where σ ak is the vertical stress at the calculation point, is the friction angle of the rock and soil at the calculation point.

[0064] S22: Calculate the active soil resistance parameter E outside 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 soil resistance refers to the resultant force of active soil pressure above the rock surface, which is a horizontal force. a1 It is the vertical distance from the fifth support point 350 to the pile bottom 370.

[0065] Active soil resistance parameter E a1 is the resultant of active earth pressure.

[0066] Active soil resistance parameter E a1 It is based on the active earth pressure parameter p ak The first distance parameter h obtained by integration a1 It is determined based on the resultant moment theorem in mechanics.

[0067] 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 .

[0068] S231: According to the rock type of the rock-embedded section, find its Hoek-Brown constant m through Table 1 i .

[0069] Table 1 Hoek-Brown constants determined by rock type

[0070]

[0071] The values ​​in Table 1 represent the Hoek-Brown constant m i .

[0072] S232: According to Figure 3 The grading value diagram of the geological strength factor GSI of the rock mass in the rock-embedded section is shown to find the geological strength factor GSI value of the rock mass in the rock-embedded section.

[0073] S233: Obtain the disturbance coefficient D of the rock mass subjected to external loads such as excavation or blasting. The disturbance coefficient D ranges from 0 to 1, with 0 indicating no disturbance and 1 indicating severe disturbance. There are two methods for obtaining the disturbance coefficient D: one is to use empirical values, as shown in Table 2; the other is to estimate it based on measured data from previous excavation projects using the following formula:

[0074]

[0075] Among them, V UP is the average longitudinal wave velocity of the undisturbed rock mass, V P is the average longitudinal wave velocity of the rock mass after disturbance by excavation blasting.

[0076] Table 2 Disturbance degree coefficient D value table

[0077]

[0078] S234: Calculate a second distance parameter from the sixth support point 360 provided by the rock mass below the rock-embedded surface 400 to the pile bottom 370 in the pile embedding stage.

[0079] 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 the rock-embedded surface 400:

[0080]

[0081] in:

[0082]

[0083] 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.

[0084] 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 h p1 is the distance from the center of gravity of the inverted triangle to the pile bottom 370,

[0085] S24: Calculate the critical rock-socketing depth parameter h d .

[0086] Assumption (4) shows that the most unfavorable effect condition during the embedded pile stage is Condition 3, where the excavation depth is below the soil-rock interface, and the lowest row of anchor cables / supports has not yet been constructed. If the rock embedding depth is insufficient, 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.

[0087] Therefore, if Figure 4 As shown, to ensure the stability of the pile bottom 370, the critical rock-embedded depth parameter h d Need to meet the first model: E p1 h p1 +T c1 (h T1 +h d )-K e E a1 h a1 ≥0;

[0088] (501.57 / 3)*h d ^2-1.25*(20.6077*(5.667+h d )+80.42465*

[0089] (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 resultant horizontal resistance parameter of rock mass; h a1 represents the first distance parameter from the fifth support point 350 to the pile bottom 370; h p1 T represents the second distance parameter from the sixth support point 360 to the pile bottom 370; c1 represents the axial force parameter of the upper support in the embedded pile stage; h T1 Indicates the vertical distance from the first support point 310 to the excavation surface of the foundation pit; h d represents the critical rock-socketing depth parameter; K erepresents the safety factor of rock-embedded stability; E a1 Represents the active soil resistance parameter.

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

[0094] S3: In the hanging pile stage, e.g. 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 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, the horizontal resistance curve equation of the hanging pile stage is:

[0096]

[0097] F x =(24.5×tan55°×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 rock shoulder horizontal resistance parameter E 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 resultant 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 located below the second supporting point 320 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 obtained by integration a2 It is determined based on the resultant moment theorem in mechanics.

[0105] S34: Calculate the critical shoulder width B min .

[0106] According to assumptions (5) and Figure 2 It can be seen that the most unfavorable working condition in the hanging pile stage is working condition 5, which considers the working condition that the kicking foot rotates around the anchor cable or support 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, K 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 meets the second mechanical model is selected as the critical rock shoulder width parameter.

[0112] S4: As 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 conditions of the first mechanical model, the processor 100 generates information including: increasing the embedding depth.

[0114] S42 : When the design width parameter of the shoulder 500 does not satisfy the conditions of the second mechanical model, the processor 100 generates information including: increasing the design width of the shoulder 500 .

[0115] Taking into account the differences in the stratigraphic characteristics of the upper soil and lower rock, this paper applies the internationally widely used Hoek-Brown strength criterion to the calculation of the horizontal resistance of the rock-embedded portion of the support piles. It also considers the problem that when the foundation pit is excavated below 370° below the pile bottom and the support piles 300° enter the hanging pile stage, the horizontal resistance provided by the rock mass in the rock-embedded section to the hanging piles will be significantly reduced. By analyzing the two different stability failure modes in the embedded pile stage and the hanging pile stage, two limit equilibrium equations are derived, thus providing a method that can help construction personnel determine two key design parameters: the critical rock-embedded depth and the critical rock shoulder width. This can help construction personnel verify the rock-embedded stability of support piles in rigid-flexible composite foundation pit support systems.

[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: Based on 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 embedded depth parameters and design width parameters 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 foundation pit. Figure 6 In the example, the support piles 300 are embedded in the medium-weathered granite 630. The elastic modulus of the medium-weathered granite 630 is 5000 MPa, the thickness of the miscellaneous fill 610 is 2 m, and the specific gravity γ1 is 17.5 kN / E. 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 embedded pile stage:

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

[0122] For soil and water separation, u a Indicates the pressure outside 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 outside 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 support point 350 to the pile bottom 370 of the BC segment a1 :

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

[0141] 1.978+h d .

[0142] 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, including the following steps:

[0143] S231: According to the rock type of the rock-embedded section, find its Hoek-Brown constant m through Table 1 i .

[0144] The embedded rock section is moderately weathered granodiorite, and the m i =30.

[0145] S232: According to Figure 3 Find the geological strength factor GSI value of the rock mass in the rock-embedded section.

[0146] The rock in the embedded section is a moderately weathered rock mass, containing angular block folds formed by many discontinuous sets, with GSI = 40.

[0147] S233: Obtain the disturbance degree coefficient D of the rock mass subjected to external loads such as excavation or blasting.

[0148] According to previous engineering experience, D=0.5.

[0149] S234: 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 the rock-embedded surface 400:

[0150] in:

[0151]

[0152] S235: Calculate critical rock socket depth h d .

[0153] like Figure 4 As shown in the first mechanical model, in order to ensure the stability of the pile bottom 370, the critical rock-embedded depth h d Need to meet:

[0154] E p1 h p1 +T c1 (h T1 +h d )-K e E a1h a1 ≥0;

[0155] (501.57 / 3)*h d ^2-1.25*(20.6077*(5.667+h d )+80.42465*

[0156] (1.978+h d ))>0;

[0157] h d >2.8627m;

[0158] In order to facilitate the design and construction, h d =3m.

[0159] S3: Hanging pile stage.

[0160] 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 right triangle. Taking the rock embedded surface 400 as the coordinate origin, the horizontal resistance curve equation of the hanging pile stage is:

[0161]

[0162] F x =(24.5×tan55°×h)·B min 0≤h≤3m.

[0163] S32: Calculation of the horizontal resistance of the rock shoulder E P2 :

[0164]

[0165] 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.

[0166] Active soil resistance E of CD segment a2 :

[0167] E a2 =(17.5×2+23.5×5)×tan 2 (45°-55° / 2)×3=45.48kN:

[0168] A third distance h from the second supporting point 320 to the third supporting point 330 of the CD segment a2 :

[0169]

[0170] S34: Calculate the critical shoulder width Bmin .

[0171] 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:

[0172] E P2 h p2 ≥K T E a2 h a2 ;

[0173]

[0174] B min ≥0.3m.

[0175] 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 fall within the scope of the disclosure of the present invention and fall within the scope of protection 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 a limitation 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 processor for calculating critical data of rock-embedded support piles, characterized in that: The processor (100) is configured to: During the pile embedding stage, a critical rock-embedded depth parameter is calculated based on a first active soil parameter outside the foundation pit above the rock-embedded surface (400) and a rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock-embedded surface (400); wherein a minimum rock-embedded depth value that conforms to the first mechanical model is selected as the critical rock-embedded depth parameter; The first mechanical model is: E p1 h p1 +T c1 (h T1 +h d )-K e E a1 h a1 ≥0; E p1 represents the resultant horizontal resistance parameter of rock mass; h a1 represents the first distance parameter from the fifth support point (350) to the pile bottom (370); h p1 T represents the second distance parameter from the sixth support point (360) to the pile bottom (370); c1 represents the axial force parameter of the upper support in the embedded pile stage; h T1 h represents the vertical distance from the first support point (310) to the excavation surface of the foundation pit; d represents the critical rock-socketing depth parameter; K e represents the safety factor of rock-embedded stability; E a1 Represents the active soil resistance parameter.

2. The processor according to claim 1, wherein: In the hanging pile stage, a 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 to the pile bottom (370); wherein the minimum rock shoulder width value that conforms to the second mechanical model is selected as the critical rock shoulder width parameter.

3. The processor according to claim 2, wherein: The second mechanical model is: 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 K represents the fourth distance parameter from the second support point (320) to the fourth support point (340); the fourth support point (340) is the point of action of the rock shoulder horizontal resistance resultant force on the support pile (300); T Indicates the stability safety factor of the kicking foot; E a2 h represents the active earth pressure parameter outside the foundation pit below the second support point (320); a2 A third distance parameter representing the distance from the second support point (320) to the third support point (330).

4. The processor according to any one of claims 1 to 3, wherein: The processor (100) is configured to calculate the first active soil parameter outside the foundation pit above the rock-embedded surface (400) as follows: 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 a fifth support point (350) to a pile bottom (370) are calculated; the fifth support point (350) is the point of action of the active soil resistance on the support pile (300).

5. The processor according to any one of claims 1 to 4, characterized in that: The processor (100) is configured to calculate the rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock-embedded surface (400) by: Calculate the ultimate resistance parameters of the pile side inside the foundation pit below the rock surface according to the Hoek-Brown strength criterion; The resultant force parameter of the rock mass horizontal resistance 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 resultant force of the rock mass horizontal resistance on the support pile (300).

6. The processor according to any one of claims 2 to 5, characterized in that: The processor (100) is configured to calculate the second active soil parameter outside the foundation pit below the second support point (320) as follows: Calculate the resultant parameters of the active earth pressure outside the foundation pit below the second support point (320); A third distance parameter from the second support point (320) to the third support point (330) is calculated; the third support point (330) is the point of action of the active earth pressure resultant of the outer layer of the foundation pit below the second support point (320) on the support pile (300).

7. A method for calculating critical data of rock-embedded support piles, characterized in that: The method comprises: During the pile embedding stage, a critical rock-embedded depth parameter is calculated based on a first active soil parameter outside the foundation pit above the rock-embedded surface (400) and a rock mass horizontal resistance resultant force parameter provided by the rock mass below the rock-embedded surface (400); wherein a minimum rock-embedded depth value that conforms to the first mechanical model is selected as the critical rock-embedded depth parameter; The first mechanical model is: E p1 h p1 +T c1 (h T1 +h d )-K e E a1 h a1 ≥0; E p1 represents the resultant horizontal resistance parameter of rock mass; h a1 represents the first distance parameter from the fifth support point (350) to the pile bottom (370); h p1 T represents the second distance parameter from the sixth support point (360) to the pile bottom (370); c1 represents the axial force parameter of the upper support in the embedded pile stage; h T1 h represents the vertical distance from the first support point (310) to the excavation surface of the foundation pit; d represents the critical rock-socketing depth parameter; K e represents the safety factor of rock-embedded stability; E a1 Represents the active soil resistance parameter.

8. The calculation method according to claim 7, characterized in that: The method further comprises: calculating a critical rock shoulder width parameter based on a second active soil parameter outside the foundation pit below the second support point (320) and a distance from the rock shoulder horizontal resistance resultant to the pile bottom (370); wherein the minimum rock shoulder width value that conforms to the second mechanical model is selected as the critical rock shoulder width parameter; The second mechanical model is: 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 K represents the fourth distance parameter from the second support point (320) to the fourth support point (340); the fourth support point (340) is the point of action of the rock shoulder horizontal resistance resultant force on the support pile (300); T Indicates the stability safety factor of the kicking foot; E a2 h represents the active earth pressure parameter outside the foundation pit below the second support point (320); a2 A third distance parameter representing the distance from the second support point (320) to the third support point (330).

9. The calculation method according to claim 7 or 8, characterized in that: The step of calculating the first active soil parameter outside the foundation pit above the rock-embedded surface (400) comprises: 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 a fifth support point (350) to a pile bottom (370) are calculated; the fifth support point (350) is the point of action of the active soil resistance on the support pile (300).

10. The calculation method according to claim 8, characterized in that: The step of calculating the second active soil parameter outside the foundation pit below the second support point (320) is configured as follows: Calculate the resultant parameters of the active earth pressure outside the foundation pit below the second support point (320); A third distance parameter from the second support point (320) to the third support point (330) is calculated; the third support point (330) is the point of action of the active earth pressure resultant of the outer layer of the foundation pit below the second support point (320) on the support pile (300).

Images