Decision-making method and system for stable rock mass soil-rock dual-element foundation pit suspended pile design parameters

Abstract

The invention relates to the field of rock and soil, provides a decision-making method and system for stable rock mass soil-rock binary foundation pit suspended pile design parameters, and aims to solve the problem of waste of materials, construction period and energy consumption caused by overlong design length of a support pile at present. The decision-making method for the design parameters of the soil-rock dual-element foundation pit suspended pile of the stable rock mass comprises the steps that based on dual-element foundation pit soil-rock parameters, soil body part anti-sliding force, soil body part sliding force, rock mass resistance and horizontal soil body friction resistance are calculated, and a damage coefficient is calculated by introducing a damage mode expansion coefficient and a soil body friction resistance deduction coefficient; and judging the damage mode of the soil-rock binary stratum according to the size of the damage coefficient, and calculating corresponding suspended pile parameters when different types of suspended piles reach static balance in combination with the current foundation pit soil-rock parameters in the corresponding damage mode. The high-quality level of soil-rock dual-element foundation pit supporting and foot hanging pile application can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of geotechnical engineering, in particular to a method and system for determining design parameters of a hanging pile in a soil-rock dual foundation pit. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute prior art.

[0003] The hanging pile is a support pile that does not support the lower part of the rock mass of the foundation pit or is simply reinforced, the pile end is embedded in the rock mass but does not penetrate the basement, the pile end is higher than the basement, and mainly supports the upper soil. The hanging pile is a commonly used type of support for soil-rock dual deep foundation pits, and has become an important support for the high-quality development of foundation pits, especially soil-rock dual foundation pits.

[0004] Currently, the design parameters of the hanging pile of the soil-rock dual foundation pit are calculated by using finite element software, and there is no calculation theory for the hanging pile. Moreover, due to the economy, professionalism and complexity of the finite element software, the engineering design is limited, the calculation of the hanging pile is difficult, and the calculation results cannot be applied to actual engineering.

[0005] In actual engineering, the "regarding rock as soil" calculation method is used to determine the design parameters of the hanging pile of the soil-rock dual foundation pit. However, regarding the stable rock layer as a soil layer for the design of the support structure ignores the rigid embedded constraint effect provided by the stable rock mass to the pile body and the condition that the rock has no lateral pressure under the condition of stable rock mass, which leads to an excessively long design length of the support pile, causing waste of materials, construction period and energy consumption. SUMMARY

[0006] To solve the above technical problems, the present application provides a method and system for determining the design parameters of the hanging pile of the soil-rock dual foundation pit in the stable rock mass, which can establish a matching mechanical model of the hanging pile for different failure modes and improve the high-quality level of the application of the soil-rock dual foundation pit support and the hanging pile.

[0007] To achieve the above purpose, the present application adopts the following technical solutions: The first aspect of the present application provides a method for determining the design parameters of the hanging pile of the soil-rock dual foundation pit in the stable rock mass.

[0008] In one or more embodiments, a method for determining the design parameters of the hanging pile of the soil-rock dual foundation pit in the stable rock mass is provided, comprising: Based on the soil-rock parameters of the dual foundation pit, the soil body part anti-sliding force, the soil body part sliding force, the rock mass resistance and the horizontal direction soil body friction are calculated; The failure coefficient is obtained by dividing the sum of the product of the partial anti-sliding force of the soil body, the product of the failure mode expansion coefficient and the rock body resistance, and the product of the soil friction force deduction coefficient and the horizontal soil friction force by the partial sliding force of the soil body; the failure mode expansion coefficient and the soil friction force deduction coefficient are 0 or 1; The failure mode of the soil-rock binary stratum is judged according to the size of the failure coefficient, and the corresponding parameters of the hanging foot pile in static balance are calculated under the corresponding failure mode in combination with the current soil-rock parameters of the foundation pit.

[0009] As an implementation mode, in the case where the failure mode expansion coefficient and the failure mode expansion coefficient are both 0: when the failure coefficient is greater than or equal to 1, no failure or the last stage failure occurs; when the failure coefficient is less than 1, the failure mode is circular arc or circular arc-plane failure.

[0010] As an implementation mode, in the case where the failure mode expansion coefficient is 1 and the failure mode expansion coefficient is 0: when the failure coefficient is greater than or equal to 1, the failure mode is circular arc or circular arc-plane failure; when the failure coefficient is less than 1, the failure mode is cross-section failure or sliding cut failure.

[0011] As an implementation mode, in the case where the failure mode expansion coefficient and the failure mode expansion coefficient are both 1: when the failure coefficient is greater than or equal to 1, the failure mode is cross-section failure; when the failure coefficient is less than 1, the failure mode is sliding cut failure.

[0012] As an implementation mode, when the failure mode is circular arc or circular arc-plane failure, the rock-embedded depth of the single-support-point anchor-type hanging foot pile is The stress balance condition to be met is: When the hanging foot pile is a cantilever-type hanging foot pile, the rock-embedded depth of the single-support-point anchor-type hanging foot pile is The stress balance condition to be met is: The length of the hanging foot pile is ; Wherein, is the height of the soil body; is the distance between the calculation section and the rock shoulder resistance; is the distance between the calculation section and the resultant force of the earth pressure; is the distance between the rock shoulder resistance and the pile bottom; is the distance between the resultant force of the earth pressure and the pile bottom; is the embedded stability safety factor; is the partial active earth pressure of the soil body; is the rock shoulder resistance provided by the rock shoulder.

[0013] As an implementation mode, when the failure mode is cross-section failure or sliding cut failure, the rock-embedded depth of the single-support-point anchor-type hanging foot pile is The force balance condition to be met is: The rock-socketed depth of the overhanging pile is The force balance condition to be met is: The length of the overhanging pile is ; Wherein, The rock failure height is; The soil height is; The distance between the calculation section and the rock shoulder resistance is; The distance between the calculation section and the resultant of the earth pressure is; The distance between the rock shoulder resistance and the pile bottom is; The distance between the resultant of the earth pressure and the pile bottom is; The embedded stability safety factor is; The active earth pressure of the soil part is; The rock shoulder resistance provided by the rock shoulder is; The friction on the soil-rock interface is; The length of the anchor rod to the pile top is; The distance between the rock-soil friction and the pile end in the case of the overhanging overhanging pile is.

[0014] As an embodiment, when the overhanging pile meets the static force balance condition, the overhanging pile is selected, and the stability of the soil-rock dual foundation pit is calculated by using the strip method according to the corresponding failure mode.

[0015] The second aspect of the present application provides a decision system for stabilizing the design parameters of the overhanging pile of the soil-rock dual foundation pit of the rock mass.

[0016] In one or more embodiments, a decision system for stabilizing the design parameters of the overhanging pile of the soil-rock dual foundation pit of the rock mass comprises: A mechanical parameter calculation module for calculating the soil part sliding resistance, the soil part sliding force, the rock resistance and the horizontal soil friction based on the soil-rock parameters of the dual foundation pit; A failure coefficient calculation module for obtaining the failure coefficient by dividing the sum of the product of the soil part sliding resistance, the failure mode expansion coefficient and the rock resistance, the product of the soil friction deduction coefficient and the horizontal soil friction by the soil part sliding force; the values of the failure mode expansion coefficient and the soil friction deduction coefficient are 0 or 1; An overhanging pile parameter calculation module for judging the failure mode of the soil-rock dual stratum according to the size of the failure coefficient, and calculating the overhanging pile parameters corresponding to the static force balance of different types of overhanging piles under the corresponding failure mode in combination with the current soil-rock parameters of the foundation pit.

[0017] The third aspect of the present application provides a computer readable storage medium.

[0018] A computer readable storage medium having stored thereon a computer program which, when executed by a processor, implements the steps of the method for determining design parameters of a hanging foot pile in a soil-rock dual foundation pit in a stable rock mass as described above.

[0019] A fourth aspect of the present application provides an electronic device.

[0020] An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, wherein the processor implements the steps of the method for determining design parameters of a hanging foot pile in a soil-rock dual foundation pit in a stable rock mass as described above when executing the program.

[0021] Compared with the prior art, the present application has the following beneficial effects: The present application introduces a failure mode expansion coefficient and a soil friction force deduction coefficient to calculate a failure coefficient on the basis of calculating soil partial sliding force, soil partial sliding force, rock resistance and horizontal soil friction, uses the size of the failure coefficient to judge the failure mode of the soil-rock dual stratum, considers the rigid embedded constraint effect provided by the rock mass to the pile body and the condition that the rock has no lateral pressure in the stable rock mass, and then calculates the corresponding hanging foot pile parameters when different types of hanging foot piles reach static equilibrium in combination with the current foundation pit soil-rock parameters under the corresponding failure mode, so that the waste problems of material, construction period and energy consumption caused by the excessively long design length of the supporting pile are avoided, the high-quality level of the soil-rock dual foundation pit supporting and the hanging foot pile application is improved, and a reference is provided for scientific utilization of rock mass structure. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the description, explain the present application. The present application is shown by way of illustration in the drawings and is not meant to be limited thereto but is provided for explanatory purposes.

[0023] Figure 1 is a decision-making method flow chart of design parameters of a hanging foot pile in a soil-rock dual foundation pit in a stable rock mass according to an embodiment of the present application; Figure 2 is a calculation model under a circular arc failure mode according to an embodiment of the present application; Figure 3 is a calculation model of a circular arc-plane failure mode according to an embodiment of the present application; Figure 4 is a stress model of a sliding rock mass according to an embodiment of the present application; Figure 5 is a calculation model under a cross-section failure mode according to an embodiment of the present application; Figure 6 is a calculation model under a sliding cross-section failure mode according to an embodiment of the present application; Figure 7is a stress analysis model of a single support point anchor type of a hanging leg pile in a circular arc or circular arc-plane failure mode according to an embodiment of the present application; Figure 8 is a stress analysis model of a cantilever type of a hanging leg pile in a circular arc or circular arc-plane failure mode according to an embodiment of the present application; Figure 9 is a stress analysis model of a single support point anchor type of a hanging leg pile in a cutting surface or sliding cutting failure mode according to an embodiment of the present application; Figure 10 is a stress analysis model of a cantilever type of a hanging leg pile in a cutting surface or sliding cutting failure mode according to an embodiment of the present application; Figure 11 is a finite element model according to an embodiment of the present application; Figure 12 is a comparison between a simulation result of a horizontal displacement of a pile body of a supporting pile and monitoring data according to an embodiment of the present application; Figure 13 is a failure result of a finite element simulation according to an embodiment of the present application; Figure 14 is a shear stress of a pile body of a finite element according to an embodiment of the present application; Figure 15 is a foundation pit diagram of a certain project according to an embodiment of the present application; Figure 16 is a potential sliding surface of a foundation pit according to an embodiment of the present application; Figure 17 is an optimized finite element model according to an embodiment of the present application; Figure 18 is a failure mode of a foundation pit of Figure 15 according to an embodiment of the present application; Figure 19 is a displacement comparison diagram of a hanging leg pile according to an embodiment of the present application; Figure 20 is a supporting structure design diagram according to an embodiment of the present application; Figure 21 is a schematic diagram of an HLC combined steel pile according to an embodiment of the present application. DETAILED DESCRIPTION

[0024] The present application will be further described below with reference to the drawings and embodiments.

[0025] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Figure 1 A schematic diagram illustrating the decision-making principle of the design parameters for the suspended piles in a stable rock mass dual-element foundation pit according to an embodiment of the present invention is provided. Based on... Figure 1 The decision-making method for the design parameters of the stable rock mass soil-rock dual-element foundation pit suspended pile in this embodiment may include the following steps S101~S103.

[0028] The specific implementation process of steps S101 to S103 is as follows: Step S101: Based on the dual-element foundation pit soil and rock parameters, calculate the soil part anti-sliding force, soil part sliding force, rock mass resistance, and horizontal soil friction. Step S102: The failure coefficient is obtained by summing the product of the soil partial sliding force, the failure mode propagation coefficient and the rock mass resistance, and the product of the soil friction deduction coefficient and the horizontal soil friction. The failure coefficient is obtained by quotienting the soil partial sliding force. The failure mode propagation coefficient and the soil friction deduction coefficient are 0 or 1. Step S103: Determine the failure mode of the soil-rock dual-layer stratum based on the magnitude of the failure coefficient. Under the corresponding failure mode, combine the current soil and rock parameters of the foundation pit to calculate the corresponding parameters of the suspended piles when different types of suspended piles reach static equilibrium.

[0029] Under stable rock mass conditions, soil-rock dual-element foundation pits exhibit four failure modes: circular arc, circular arc-plane, tangential, and sliding shear. As the thickness of the overlying soil layer increases, the failure mode of soil-rock dual-element foundation pits gradually transitions from circular arc failure to circular arc-plane failure, tangential failure, and sliding shear failure.

[0030] (a) For circular arc failure mode: When the excavation depth of the foundation pit is within the soil mass, the soil-rock dual foundation pit will experience circular arc sliding failure. The soil mass will generate overall failure sliding force and anti-sliding force. When the sliding force is greater than the anti-sliding force, it is the circular arc sliding mode of the soil foundation pit. If the radius of the circular arc is exactly on the soil-rock interface during the circular arc sliding, the circular arc may intersect with the excavation surface at the soil-rock interface. Figure 2 For the computational model of the circular failure mode, the resisting force and sliding force of the soil are calculated using the slice method. Soil slices... gravity The force is decomposed into tangential and normal forces along the center point of the sliding surface. The two components of the reaction force of the soil below the sliding surface are expressed as follows: and .

[0031] (1); (2); In the formula: For soil strips gravity, For soil strips cohesion, For soil strips The internal friction angle, For soil strips The angle between the sliding surface and the horizontal direction, For soil strips The length of the sliding surface; determining the geometric parameters of the sliding surface, circular arc surface. The mathematical expression is: (3); The weight of a soil strip can be expressed as : (4); In the formula: The unit weight of the soil. The thickness of the soil; Other parameter expressions: (5); (6); (7); (8); In the formula: This represents the normal stress at the slip surface of the soil strip. Let be the radius of the sliding surface. For soil strips The length of the glide slope, Given the coordinates of the center of the circle during circular sliding; calculate the soil's resistance to sliding and the sliding force, and the sliding force... The anti-sliding force is generated by the tangential component of the soil's weight. Generated by the cohesion and internal friction of the soil, a function is defined for ease of calculation. 、 、 These three functions; (9); (10); (11); (12); (13); wherein, is the angle between the lower surface of the soil body and the horizontal direction; is the internal friction angle of the soil body; is the cohesion of the soil strip.

[0032] Since the application of the analytical solution requires determination of the center and radius of the circular arc, the slip line field method is applied to obtain the slip curve of the slope, determine the center coordinate and the radius When , partial sliding failure of the soil body occurs.

[0033] (b) For the circular arc-plane failure mode: When the foundation pit is excavated to the soil-rock interface and below, the overlying soil circular arc slides to the rock surface, at which time the upper soil body is constrained by the rock mass. When the downslope force is greater than the soil body's anti-sliding force and the soil-rock interface frictional resistance, circular arc-plane failure occurs. Figure 3 is the calculation model of the circular arc-plane failure mode.

[0034] The residual downslope force of the partially circular-arc-sliding soil body is calculated by the strip method: (14); The stress analysis of the rock mass is shown in Figure 4 , the angle between the sliding surface and the horizontal plane is , the rock mass part is subjected to the normal force perpendicular to the sliding surface, the anti-sliding force parallel to the sliding surface, the combined force of the soil-rock gravity , and the length of the rock mass sliding surface is ; limit equilibrium analysis is performed on the rock mass part.

[0035] The expression of the gravity of the rock mass is: (15); The anti-sliding force of the rock mass cutting angle is : (16); The sliding force of the rock mass cutting angle is : (17); The expression of the rock mass resistance is: (18); ​​In the formula: is the specific gravity of the rock mass, is the internal friction angle of the rock mass, is the cohesion of the rock mass; when the rock mass is in a limit equilibrium state , the simultaneous equations (16), (17), and (18) are obtained: (19); When the lower stable rock mass is subjected to a soil load with a size of , the expression of the failure range : (20); When , the overall anti-sliding force of the rock mass is greater than the sliding force of the rock mass, the rock mass is in a stable state, and no cutting angle failure occurs, and the foundation pit is in a circular-arc-plane failure mode.

[0036] (c) For the cutting surface failure mode: The foundation pit excavation working condition enters the depth of the rock mass, the overlying soil circular-arc slides to the surface of the rock mass, and when the shear strength of the rock mass is insufficient to resist the soil downward sliding force and the shear strength of the rock mass is just enough to resist the downward sliding force of the upper soil, the rock mass is damaged along the extension line of the soil circular-arc failure surface. Figure 5 is the calculation model under the cutting surface failure mode.

[0037] The expression of the rock mass resistance is the same as formula (18), the expression of the residual downward sliding force of the soil partial circular-arc sliding is formula (14), when , the rock mass is in a stable state, and the shear strength of the rock mass is just enough to resist the downward sliding force of the upper soil, and no cutting angle failure occurs, and when , the foundation pit is in a cutting surface failure mode.

[0038] (d) For the sliding-cutting failure mode: The excavation depth of the foundation pit is large, the upper soil is thick, the soil downward sliding force attenuates to a certain degree along the soil-rock interface, the residual downward sliding force is just in shear balance with the rock mass wedge, and a circular-arc-plane-cutting angle failure is generated. Figure 6 is the calculation model under the sliding-cutting failure mode.

[0039] The expression of the rock mass resistance is the same as formula (18), the expression of the residual downward sliding force of the soil partial circular-arc sliding is formula (14), when , the overall downward sliding force generated when the overlying soil slides is greater than the rock mass resistance , at this time, the rock mass is in a non-stable state, and cutting angle failure occurs, and the failure mode is sliding-cutting failure; wherein, is the horizontal soil friction resistance.

[0040] When only the soil is assessed for failure mode, the failure mode propagation factor is 0; when the rock mass resistance is added to the assessment of the soil failure mode, the failure mode propagation factor is 1; when the horizontal soil friction is deducted from the failure mode assessment, the soil friction deduction factor is 1; when the horizontal soil friction is not deducted from the failure mode assessment, the soil friction deduction factor is 0.

[0041] When both the failure mode propagation coefficient and the failure mode propagation coefficient are 0: when the failure coefficient is greater than or equal to 1, no failure occurs or the previous stage failure occurs; when the failure coefficient is less than 1, the failure mode is circular arc or circular arc-plane failure.

[0042] When the failure mode propagation coefficient is 1 and the failure mode propagation coefficient is 0: when the failure coefficient is greater than or equal to 1, the failure mode is circular arc or circular arc-plane failure; when the failure coefficient is less than 1, the failure mode is shear failure or sliding failure.

[0043] When both the failure mode propagation coefficient and the failure mode propagation coefficient are 1: when the failure coefficient is greater than or equal to 1, the failure mode is shear failure; when the failure coefficient is less than 1, the failure mode is sliding failure.

[0044] In the determination of failure modes of soil-rock dual-element strata, a failure coefficient is introduced. S Quantitatively characterize its damage mode. When S When ≥1, it means that the anti-slip force is sufficient to counteract the sliding force, and no failure occurs or the previous stage of failure occurs; conversely, when S When the value is less than 1, it means that the sliding force dominates, and failure will occur. For different failure modes, a failure mode propagation coefficient is introduced. With soil friction deduction factor When making distinctions, only the soil is assessed for failure mode. When adding rock mass resistance ; When deducting horizontal soil friction Based on different coefficient values, S The loads and constraints imposed on the values ​​are different. , , It is based on the damage coefficient under different damage modes. S The value expression is as follows: (twenty one); use S The process of determining the destruction mode based on the value is shown in Table 1.

[0045] Table 1. Damage Mode Judgment Table;

[0046] In the circular or circular-plane failure mode, the single-point anchor type of the overhanging pile is subjected to the earth pressure of the soil outside the pit due to unloading , the transverse support force provided by the anchor rod , and the rock shoulder resistance provided by the rock shoulder ; after excavation, the overhanging pile is in a state of force balance, and the stress analysis model of the single-point anchor type of the overhanging pile is shown in Figure 7 .

[0047] The active earth pressure of the soil is The expression is: (22); The horizontal resistance provided by the rock shoulder is: (23); When the overhanging pile is in static equilibrium, the static equilibrium relationship of the three is: (24); In the formula: is the self-stable height of the soil in Rankine earth pressure calculation; is the active earth pressure coefficient, is the width of the rock shoulder, is the depth of the rock-embedded overhanging pile in static equilibrium, The expression of (25); In the circular or circular-plane failure mode, the bending moment and the shear force V of the overhanging pile are calculated as follows: (26); (27); In the formula: L is the length of the overhanging pile, is the length of the anchor rod to the top of the pile, is the distance between the calculation section and the rock shoulder resistance, is the distance between the calculation section and the earth pressure resultant force.

[0048] The embedded depth of the overhanging pile of the single-layer anchor rod should meet the stability requirements of the following formula: (28); When the overhanging pile is cantilevered, there is no need to consider , as shown in Figure 8 , at this time, the embedded depth should meet the requirements of the embedded stability: (29); When the failure mode is circular arc failure or circular arc-plane failure, the rock mass remains stable and does not fail. In this case, the embedment depth of the toe pile only needs to meet the force equilibrium condition, and the length of the toe pile... .in, The height of the soil mass; To calculate the distance between the cross section and the rock shoulder resistance; To calculate the distance between the cross section and the resultant earth pressure; This is the distance between the rock shoulder resistance and the pile bottom; This is the distance between the resultant earth pressure force and the bottom of the pile; This is the safety factor for embedded stability; This refers to the active earth pressure on the soil mass. The rock shoulder resistance provided for the rock shoulder.

[0049] In the shear or slip failure mode, the suspended pile is subjected to soil pressure, rock shoulder reaction force, and frictional force at the soil-rock interface. T The stress analysis model of a single-point anchored suspended pile is as follows: Figure 9 As shown; From geometric relationships, the rock mass failure height can be obtained. The expression: (30); The expression for the frictional force T at the soil-rock interface: (31); in, The pressure on the soil; The angle between the soil-rock interface and the horizontal direction; The unit weight of the soil.

[0050] The bending moment of the suspended pile under the shear or slip failure mode and shear force V Calculate using the following formula: (32); (33); In the case of a single-point anchored suspended pile, the distance between the soil friction force and the pile tip; For the first i The lateral support force provided by each anchor bolt.

[0051] The embedment depth of a single-point anchored heap pile should meet the following stability requirements: (34); When the suspended pile is cantilevered, no consideration is needed. , the stress analysis model of the cantilevered pile is as shown in Figure 10 At this time, the embedded depth should meet the requirements of embedded stability: (35); When the failure mode is a shear surface or a sliding shear failure, the rock mass is damaged, at which time the rock-embedded depth of the pile needs to meet not only the stress balance condition but also the stability requirements for resisting rock mass damage, so the rock-embedded depth is selected as the maximum value between , The length of the cantilevered pile is .

[0052] wherein, is the rock mass damage height; is the soil height; is the distance between the calculation section and the rock shoulder resistance; is the distance between the calculation section and the resultant force of the earth pressure; is the distance between the rock shoulder resistance and the pile bottom; is the distance between the resultant force of the earth pressure and the pile bottom; is the embedded stability safety factor; is the active earth pressure of the soil part; is the rock shoulder resistance provided by the rock shoulder; is the friction force on the soil-rock interface; is the length of the anchor rod to the pile top; is the distance between the rock-soil friction force and the pile end in the case of the cantilevered pile.

[0053] When the cantilevered pile meets the static force balance condition, the pile is selected, and the stability of the soil-rock dual foundation pit is calculated according to the corresponding failure mode using the strip method.

[0054] In a certain soil-rock dual deep foundation pit project, the overlying soil layer is silty clay with a thickness of about 8.5m, and the underlying rock mass is tuff. Given the soil layer parameters and rock mass parameters, the supporting pile is 34m long, and the open excavation method is used for construction. In this embodiment, a finite element model is established using PLAXIS 3D software, and the steel pipe pile is simulated using a reduced thickness elastic plate according to the equivalent moment of inertia principle. It should be noted that in other embodiments, other existing software can also be used to establish a finite element model.

[0055] The contact between the soil, rock and elastic plate is simulated using an interface element, the crown beam, waist beam and anchoring section are simulated using an Embedded pile element, and the anchor cable is simulated using a point-to-point anchor element. The HSS model, which is more accurate in expressing the stress-strain path of the soil, is selected to simulate the soil layer, and the Mohr-Coulomb model is used to simulate the rock mass. The finite element model is as shown in Figure 11 .

[0056] Table 2 rock mass parameters;

[0057] The monitoring data and the finite element simulation results are selected for comparison. Process a and process b are excavation to the soil-rock interface and excavation to 25 m pit bottom, respectively. The simulation results of the horizontal displacement of the pile body are compared with the monitoring data as shown in Figure 12 . Both are basically consistent, proving that the numerical model parameters and element selection are scientific, and the subsequent research results are reasonable.

[0058] According to the value judgment method in Table 2 S , the failure mode is judged, S The value calculation requires related data such as Table 3. The failure mode is circular arc sliding, and the finite element simulation failure mode is shown in Figure 13 . The above stratum parameters and supporting parameters are substituted into equations (22), (23), (24), and (27) to calculate the limit equilibrium depth of 5.26 m, and the calculation results are shown in Table 3. The finite element simulation failure results and the pile shear force are shown in Figure 13 and Figure 14 .

[0059] Table 3 calculation results;

[0060] According to the finite element method to simulate the shear stress results, the failure mode under this stratum condition is circular arc sliding, and the shear force of the hanging foot pile at 13.6 m is 0, with an error of 0.16 m between the theoretical calculation of 13.76 m, and an error rate of about 1.2%, verifying the rationality of the theoretical derivation of the failure mode and the static equilibrium calculation.

[0061] As shown in Figure 15 , a certain soil-rock dual-element foundation pit is proposed to be excavated to a depth of 13.6 m, of which the soil body is 7.6 m and the rock body is 6 m. The foundation pit safety level is two, and the pile top displacement control value is 20 mm. Its stratum condition is in turn miscellaneous fill, loess, silty clay, dissolved broken dolomite and medium weathered dolomite. According to the survey report and regional geological analysis, the underlying rock mass of this foundation pit is stable, and the hanging foot pile is proposed to be used for support, and the foundation pit support design parameters are shown in Table 4.

[0062] Table 4 stratum parameters;

[0063] Based on the parameters of the above-mentioned engineering example in a certain area, the overlying soil layer is simplified as homogeneous silty clay, the underlying rock mass is medium weathered dolomite, and the failure mode criterion is combined with the proposed failure coefficient R value to judge the failure mode under this stratum, and the calculation results are shown in Table 5.​

[0064] Table 5. Failure mode calculation and determination results

[0065] For example, the safety factor of the foundation pit is calculated using the matlab program, the potential sliding surface is searched, and the minimum sliding safety factor is 0.92. The potential sliding surface of the foundation pit is shown in Figure 16 .

[0066] According to the deformation requirement, the hanging foot pile is designed, the soil pressure is triangular load, and the stiffness calculation results are shown in Table 6. The φ800 reinforced concrete pile is selected, the rock shoulder width is 1m, the rock-embedded depth of the hanging foot pile static force balance is h 1=1.3m, the rock-embedded depth is 1.5m, and the total pile length of the hanging foot pile is 8.3m.

[0067] Table 6. Stiffness calculation results

[0068] Based on the circular arc failure mode of the foundation pit, the above hanging foot pile is selected, and the safety factor of the overall stability of the foundation pit is calculated according to the building foundation and slope engineering design specification: K . (36); (37); In the formula: is the diameter of the supporting pile; is the distance between the supporting pile shafts; is the design value of the tensile strength of concrete; is the cross-sectional width of the pile body; is the effective height of the pile body cross section; is the design value of the tensile strength of the stirrup; is the cross-sectional area of the stirrup of the pile body; is the shear resistance provided by the retaining member water curtain to the failure sliding soil; is the spacing of the stirrup along the pile body.

[0069] The supporting pile adopts φ10@150 stirrup and 12φ20 main reinforcement, and the pile spacing is 1.5m. The safety factor of the overall stability of the foundation pit is calculated: K . ; The stability safety factor meets the overall stability safety factor of the secondary supporting structure, which indicates that the foundation pit is in a safe state under the supporting condition.

[0070] A three-dimensional finite element model including soil, rock, suspended pile, supporting structure, etc. is established by using PLAXIS 3D software. According to the "depth effect" performance, based on the experience of a single unit of alluvial landform foundation pit engineering, the soil-rock bimodal foundation pit soil and rock constitutive relationship of soil not more than 18m depth is adopted MC model, the optimized finite element model is shown as Figure 17 , and the failure mode of the foundation pit is shown as Figure 18 .

[0071] Through the simulation of the finite element software, the failure mode under the soil-rock stratum condition is circular arc failure; the stress calculation results of the optimized suspended pile are basically consistent, and the foundation pit is in a stable state.

[0072] The displacement of the suspended pile is calculated according to the stiffness of the suspended pile, and the calculation results are compared with the numerical simulation and field monitoring, and the comparison results are shown as Figure 19 . It can be seen that the results obtained by the three methods are basically consistent, proving that the selection is reasonable.

[0073] Using full recovery steel sheet pile to replace reinforced concrete suspended pile can reduce the carbon emissions of reinforced concrete pile in terms of reduced production, recycling and reuse, etc. The maximum recycling number of the enclosure structure is 6, and the material loss rate is 16.67% each time. The carbon emissions of material production and material transportation of single reinforced concrete pile and HLC (i.e. H-shaped steel and Larsen steel sheet pile combination) steel sheet pile are calculated according to the existing known standard building carbon emission calculation method, and the calculation results are shown in Table 7.

[0074] Table 7 Carbon emissions of different material suspended piles

[0075] When using reinforced concrete pile for support, the bending stiffness of the suspended pile is much larger than the minimum required stiffness for support. The bending stiffness of the HLC steel sheet pile combined with H700x300x13x24 and IV Larsen steel sheet pile is , and the support structure can be fully recycled, which meets the demand of green development. The displacement of the HLC steel sheet pile is calculated: . The calculation results prove that the deformation of the combined steel sheet pile can meet the requirements of the foundation pit deformation, and can be used for support. The supporting structure is shown as Figure 20 , and the HLC cross section is shown as Figure 21 .

[0076] In one or more embodiments, a decision system for stabilizing rock-soil bimodal foundation pit suspended pile design parameters is also provided, which can be realized in software. The decision system for stabilizing rock-soil bimodal foundation pit suspended pile design parameters includes the following software modules: a mechanical parameter calculation module configured to calculate soil body part sliding resistance, soil body part sliding force, rock body resistance and horizontal direction soil body friction based on the soil-rock parameter of the dual foundation pit; a damage coefficient calculation module configured to obtain a damage coefficient by dividing the sum of the product of the soil body part sliding resistance, a damage mode expansion coefficient and the rock body resistance, the product of a soil body friction resistance deduction coefficient and the horizontal direction soil body friction, and the soil body part sliding force; the damage mode expansion coefficient and the soil body friction resistance deduction coefficient are 0 or 1; a hanging pile parameter calculation module configured to determine the damage mode of the soil-rock dual stratum according to the size of the damage coefficient, and calculate the corresponding hanging pile parameters of different types of hanging piles reaching static balance in combination with the current soil-rock parameter of the foundation pit under the corresponding damage mode.

[0077] It should be noted that each module in the decision system for the design parameters of the hanging pile of the stable rock-soil dual foundation pit in the embodiments of the present application corresponds to each step in the decision method for the design parameters of the hanging pile of the stable rock-soil dual foundation pit in the above embodiments, and the specific implementation process is the same, which will not be repeated here.

[0078] The structure of the electronic device provided in the embodiments of the present application will be described in detail below. The electronic device provided in the embodiments of the present application includes at least one processor, a memory, a user interface and at least one network interface. Each component in the decision system for the design parameters of the hanging pile of the stable rock-soil dual foundation pit is coupled together through a bus system. It can be understood that the bus system is used to realize the connection and communication between the components. In addition to the data bus, the bus system also includes a power bus, a control bus and a state signal bus.

[0079] The user interface can include a display, a keyboard, a mouse, a trackball, a click wheel, a key, a button, a touchpad or a touch screen, etc.

[0080] It can be understood that the memory can be a volatile memory or a non-volatile memory, and can also include both volatile and non-volatile memories. The memory in the embodiments of the present application can store data to support the operation of the terminal. Examples of the data include any computer programs for operating on the terminal, such as an operating system and an application program. The operating system contains various system programs, such as a framework layer, a core library layer and a driver layer, for realizing various basic services and processing hardware-based tasks. The application program can include various application programs.

[0081] In some embodiments, the decision system for the design parameters of the soil-rock dualistic foundation pit underpinning pile in stable rock mass provided by the embodiments of the present application can be implemented in a combination of software and hardware. For example, the decision system for the design parameters of the soil-rock dualistic foundation pit underpinning pile in stable rock mass provided by the embodiments of the present application can be a processor in the form of a hardware decoding processor, which is programmed to execute the decision method for the design parameters of the soil-rock dualistic foundation pit underpinning pile in stable rock mass provided by the embodiments of the present application. For example, the processor in the form of a hardware decoding processor can be one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic elements.

[0082] For example, the processor 301 can be an integrated circuit chip with a processing capability of signals, such as a general-purpose processor, a digital signal processor (DSP), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc., where the general-purpose processor can be a microprocessor or any conventional processor.

[0083] For the example of the decision system for the design parameters of the soil-rock dualistic foundation pit underpinning pile in stable rock mass implemented in hardware provided by the embodiments of the present application, the apparatus provided by the embodiments of the present application can be directly implemented by the processor 301 in the form of a hardware decoding processor, such as one or more application-specific integrated circuits (ASICs), DSPs, programmable logic devices (PLDs), complex programmable logic devices (CPLDs), field-programmable gate arrays (FPGAs), or other electronic elements, to execute the decision method for the design parameters of the soil-rock dualistic foundation pit underpinning pile in stable rock mass provided by the embodiments of the present application.

[0084] The memory in the embodiments of the present application is used to store various types of data to support the operation of the decision system for the design parameters of the soil-rock dualistic foundation pit underpinning pile in stable rock mass, or to store instructions for executing the decision method for the design parameters of the soil-rock dualistic foundation pit underpinning pile in stable rock mass provided by the embodiments of the present application. Figure 1program code of the method. Examples of such data include any executable code such as an executable instruction for operating on a decision system for design parameters of a hanging pile in a stable rock-soil dual foundation pit, and a program implementing the decision method for design parameters of a hanging pile in a stable rock-soil dual foundation pit according to an embodiment of the present application can be included in the executable instruction.

[0085] In particular, according to embodiments of the present application, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present application include a computer program product comprising a computer program which is carried on a computer readable medium, the computer program comprising instructions for executing various functions defined in the apparatus of the present application when the computer program is executed by a central processing unit. Figure 1 program code of the method. In such embodiments, the computer program can be downloaded and installed from a network through a communication section, and / or installed from a detachable medium. When the computer program is executed by the central processing unit, various functions defined in the apparatus of the present application are executed.

[0086] The present application is described with reference to the flowcharts and / or block diagrams of the methods, apparatus (system) and computer program products of embodiments of the present application. It should be understood that each flow and / or block in the flowcharts and / or block diagrams, and combinations of flows and / or blocks in the flowcharts and / or block diagrams can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing apparatus to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing apparatus produce a device that implements the functions specified in the flowcharts and / or block diagrams. Figure 1 one flow or multiple flows and / or blocks Figure 1 an apparatus that implements the functions specified in one block or multiple blocks.

[0087] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. The present application can have various modifications and changes for those skilled in the art. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A decision-making method for stabilizing the design parameters of a soil-rock dual foundation pit underpinning pile, characterized in that, The method comprises the following steps: Based on the soil-rock parameters of the two-element foundation pit, the soil partial sliding resistance, the soil partial sliding force, the rock resistance and the horizontal soil friction are calculated. The failure coefficient is obtained by dividing the product of the soil partial sliding resistance, the failure mode expansion coefficient and the rock resistance, the product of the soil friction deduction coefficient and the horizontal soil friction, and the soil partial sliding force. The failure mode expansion coefficient and the soil friction deduction coefficient are 0 or 1. According to the size of the failure coefficient, the failure mode of the soil-rock two-element stratum is determined, and the corresponding parameters of the hanging foot pile of different types are calculated when the hanging foot pile reaches static equilibrium under the corresponding failure mode.

2. The method for determining the design parameters of the rock-soil dual foundation pit underpinning pile of the stable rock mass according to claim 1, characterized in that, In the case where the failure mode expansion coefficient and the failure mode expansion coefficient are both 0: when the failure coefficient is greater than or equal to 1, no failure or the previous stage failure occurs; when the failure coefficient is less than 1, the failure mode is circular arc or circular arc-plane failure.

3. The method of claim 1, wherein the method further comprises: determining the design parameters of the soil-rock bimodal foundation pit underpinning pile based on the stability of the rock mass. In the case where the failure mode expansion coefficient is 1 and the failure mode expansion coefficient is 0: when the failure coefficient is greater than or equal to 1, the failure mode is circular arc or circular arc-plane failure; when the failure coefficient is less than 1, the failure mode is cross-section failure or sliding cut failure.

4. The method of claim 1, wherein the method further comprises: determining the design parameters of the soil-rock bimodal foundation pit underpinning pile based on the stability of the rock mass. In the case where the failure mode expansion coefficient and the failure mode expansion coefficient are both 1: when the failure coefficient is greater than or equal to 1, the failure mode is cross-section failure; when the failure coefficient is less than 1, the failure mode is sliding cut failure.

5. The method for determining the design parameters of the rock-soil dual foundation pit underpinning pile of the stable rock mass according to claim 1, characterized in that, When the failure mode is circular arc or circular arc-plane failure, the rock-socketed depth of the single-support-point anchor-lifting pile The force balance condition to be met is: When the failure mode is circular arc or circular arc-plane failure, the rock-socketed depth of the single-support-point anchor-lifting pile The force balance condition to be met is: The length of the lifting pile ​ wherein, H is the height of the soil mass; D is the distance between the calculated section and the rock shoulder resistance; D is the distance between the calculated section and the resultant of the earth pressure; D is the distance between the rock shoulder resistance and the pile bottom; D is the distance between the resultant of the earth pressure and the pile bottom; K is the factor of safety for the embedded stability; P is the active earth pressure of the soil mass; R is the rock shoulder resistance provided by the rock shoulder.

6. The method for determining the design parameters of the rock-soil dual foundation pit underpinning pile of the stable rock mass according to claim 1, characterized in that, When the failure mode is the section failure or the sliding shear failure, the rock-socketed depth of the single-fulcrum anchor-lifting pile The force balance condition to be met is: When the failure mode is the section failure or the sliding shear failure, the rock-socketed depth of the single-fulcrum anchor-lifting pile The force balance condition to be met is: The length of the single-fulcrum anchor-lifting pile The length of the single-fulcrum anchor-lifting pile wherein, is the height of the rock mass failure; is the height of the soil mass; is the distance between the calculated section and the rock shoulder resistance; is the distance between the calculated section and the resultant of the earth pressure; is the distance between the rock shoulder resistance and the pile bottom; is the distance between the resultant of the earth pressure and the pile bottom; is the embedded stability safety factor; is the active earth pressure of the soil mass portion; is the rock shoulder resistance provided by the rock shoulder; is the friction on the rock-soil interface; is the length of the anchor to the top of the pile; is the distance of the rock-soil friction from the pile end in the case of a cantilevered footing pile.

7. The method for determining the design parameters of the rock-soil dual foundation pit underpinning pile of the stable rock mass according to claim 1, characterized in that, When the hanging foot pile satisfies the static equilibrium condition, the hanging foot pile is selected, and the stability of the soil-rock two-element foundation pit is calculated by using the strip method according to the corresponding failure mode.

8. A decision system for stabilizing the design parameters of a soil-rock dual foundation pit underpinning pile, characterized in that, The decision method for the design parameters of the hanging foot pile of the stable rock mass soil-rock two-element foundation pit according to any one of claims 1-7 comprises: A mechanical parameter calculation module is configured to calculate the soil partial sliding resistance, the soil partial sliding force, the rock resistance and the horizontal soil friction based on the soil-rock parameters of the two-element foundation pit. A failure coefficient calculation module is configured to obtain the failure coefficient by dividing the product of the soil partial sliding resistance, the failure mode expansion coefficient and the rock resistance, the product of the soil friction deduction coefficient and the horizontal soil friction, and the soil partial sliding force. The failure mode expansion coefficient and the soil friction deduction coefficient are 0 or 1. A hanging foot pile parameter calculation module is configured to determine the failure mode of the soil-rock two-element stratum according to the size of the failure coefficient, and calculate the corresponding parameters of the hanging foot pile of different types when the hanging foot pile reaches static equilibrium under the corresponding failure mode in combination with the current foundation pit soil-rock parameters.

9. A computer readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the steps in the decision method for the design parameters of the hanging foot pile of the stable rock mass soil-rock two-element foundation pit according to any one of claims 1-7.

10. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, The processor executes the program to implement the steps in the decision method for the design parameters of the hanging foot pile of the stable rock mass soil-rock two-element foundation pit according to any one of claims 1-7.

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