Method for calculating impact force of debris flow and application, and design method of fender pile array

Abstract

The present application discloses a method for measuring impact force of debris flow and application, and a design method for barrier energy dissipation pile array. The method for measuring vertical impact force of debris flow measures the tangential velocity of debris flow at the impact point to measure the vertical impact force distribution of debris flow on the impact point. Further, the design method for pile array simplifies the free section of energy dissipation pile as a cantilever beam, which generates a bending resistance when impacted by debris flow, and the bending resistance continuously works to dissipate the impact kinetic energy of debris flow. According to the motion characteristics of debris flow, the impact time and distance parameters are further derived to solve the problems of measuring and designing the stability parameters of single energy dissipation pile, the energy dissipation parameters of barrier energy dissipation pile array, and the number parameters of barrier energy dissipation pile array. The present application also provides the application of each measuring and designing method. The present application provides a more scientific and perfect solution for the energy dissipation design of barrier energy dissipation pile array to resist the impact damage of rockfall and debris flow caused by landslide disaster.

Description

TECHNICAL FIELD

[0001] The present application relates to a collapse landslide disaster prevention measure, in particular to a design method of a blocking and energy dissipation pile array for resisting the impact of a collapse landslide debris flow, and a design method thereof, belonging to the technical field of mountain disaster prevention. BACKGROUND

[0002] Collapse landslide disasters are a kind of disasters with great harm in mountainous areas due to their high frequency, high speed, strong impact, and wide distribution. The essence of collapse landslide is that the soil / rock mass on the slope deforms under the influence of comprehensive internal and external forces, and then slides down along a certain weak surface / weak zone under the action of gravity. The moving rock-soil mass is called collapse body / landslide body / displacement body / sliding body, etc., and the underlying rock-soil mass that has not moved is called slide bed. During the downward movement of the collapse body, it will collide and rub with the slide bed, resulting in decomposition. The main decomposition components are stones of different diameters and debris flow-like "fluid" state. Debris flow refers to a kind of discrete and broken fluid with high speed and bulk state formed after the destruction of rock or soil slope. Landslide debris flow often has characteristics such as extraordinary high speed, long-range displacement, large volume, large energy, and large impact area, and is therefore the main factor causing large-scale disastrous accidents and serious loss of life and property in collapse landslides.

[0003] The applicant submitted a Chinese patent with application publication number CN111809537A on October 23, 2020, which discloses a collapse landslide blocking and energy dissipation pile array, which is an energy dissipation structure for collapse landslide disasters. When subjected to different orders of magnitude of rolling stone impact force, the blocking and energy dissipation pile array fully utilizes the elastic deformation of the free section of the structure or the plastic deformation of the foundation soil of the anchoring section to dissipate the kinetic energy of the rolling stone, thereby effectively reducing the harm of the rolling stone and the consequences and losses caused thereby. The design method of the blocking and energy dissipation pile array provided in the application determines the structural parameters of the blocking and energy dissipation pile array by calculating and analyzing the plastic deformation of the foundation soil of the anchoring section of the energy dissipation pile monomer, so as to ensure that the energy dissipation pile array can dissipate energy and reduce harm according to the designed deformation.

[0004] The above-mentioned barrier energy dissipation pile array is a simple, efficient and easy-to-promote landslide disaster prevention and control technical solution, and the matching design method can solve the technical problems of barrier energy dissipation pile array design in response to rockfall disasters. However, when designing to respond to the technical problems of landslide debris flow impact, the matching design method still has room for improvement, mainly including three directions: (1) The design method only considers the energy dissipation effect caused by the impact of the impact object at the moment. This concept can meet the energy dissipation design target for rockfall, but when designing the energy dissipation pile array for debris flow, the continuous energy dissipation effect of the impact process needs to be further considered, especially the energy dissipation effect under the secondary impact of the landslide body. (2) Important variables in the design of the energy dissipation pile array, such as the energy dissipation target, impact force distribution, and energy dissipation pile deformation, need to be constructed and calculated based on the impact motion characteristics of the debris flow. (3) The arrangement of the energy dissipation pile array will reinforce the foundation, so when the foundation of the pile array is good, the failure mode of the single energy dissipation pile is mainly fracture, and therefore, considering the stability and flexural deformation characteristics of the cantilever section in the design and calculation method of the energy dissipation pile array will have more engineering practical significance. SUMMARY

[0005] The purpose of the present application is to provide a barrier energy dissipation pile array design method for landslide barrier energy dissipation pile array based on the impact force motion characteristics of landslide debris flow.

[0006] To achieve the above-mentioned purpose, the present application first provides a landslide debris flow vertical impact force calculation method, and the technical scheme is as follows:

[0007] A landslide debris flow vertical impact force calculation method is used to calculate the vertical impact force P (y) distribution of debris flow on impact site A′

[0008] Firstly, the on-site investigation of the collapse and landslide hazard is carried out to obtain the landslide hazard data;

[0009] The characteristics are:

[0010] Secondly, the tangential motion velocity of the landslide debris flow at the impact calculation point o(x, y) is calculated according to formula 1

[0011] v (y) , the impact calculation point o is a different height point on the impact site A′,

[0012]

[0013] In formula 1, v (y) is the tangential motion velocity of the landslide debris flow at the impact calculation point o, m / s,

[0014] u a is the average flow velocity of the debris flow impact process, m / s, which is determined by the landslide hazard data,

[0015] y - height of impact point o, m, landslide hazard data determined,

[0016] δ - accumulation thickness of debris flow moving to impact point A', m, landslide hazard data determined;

[0017] Again, the vertical impact force P of the debris flow on the impact point o is calculated according to Formula 2 (y) ,

[0018] P (y) = αrv (y) 2 Formula 2

[0019] In Formula 2, P (y) - vertical impact force of the debris flow on the impact point o', KN,

[0020] α - dynamic pressure coefficient of the debris flow movement process, unitless, landslide hazard data determined,

[0021] ρ - debris flow density, kg / m 3 , landslide hazard data determined.

[0022] The technical principle of the above-mentioned method for measuring the vertical impact force of the landslide debris flow mainly lies in: calculating the distribution of the vertical impact force, and the key is to calculate the distribution of the vertical velocity of the debris flow movement. Any vertical section of the debris flow is intercepted, and the vertical velocity distribution profile in the downstream direction is analyzed. The velocity of the debris flow is the largest at the upper free surface, and decreases from the free surface downward, and approaches 0 at the bottom surface. Since the particle size range of the landslide debris flow varies greatly in actual engineering, and it is difficult to measure in the accumulation body stage before sliding, it is more reasonable to use the tangential velocity distribution expression independent of the particle size. The impact point A' is a patterned transparent structure, that is, the impact point A' is not designed to block the debris flow to stop it, but to make the debris flow consume energy through impact movement and accumulate behind the impact point A' (i.e. downstream of the impact point A' on the debris flow movement path). Therefore, the average flow velocity u a in Formula 1 is the average flow velocity of the debris flow during the inflow and outflow of the impact point A'. Using the existing technology, the velocity of the debris flow flowing into the impact point A' can be calculated by the landslide body position, the impact point A' position, the equivalent friction coefficient f of the debris flow movement process, and the functional theorem; the velocity of the debris flow flowing out of the impact point A' is calculated by the final accumulation position of the debris flow, the impact point A', the equivalent friction coefficient f of the debris flow movement process, and the functional theorem. After establishing the distribution function of the vertical velocity of the debris flow movement, the vertical impact force P (y) of the debris flow can be measured and calculated by using the hydrodynamic model.

[0023] The landslide debris flow vertical impact force distribution calculation method can be applied to landslide and landslide debris flow prevention and treatment engineering design, and provides landslide debris flow impact force parameters. Therefore, the application provides the following scheme.

[0024] The application of the above landslide debris flow vertical impact force calculation method in landslide / landslide debris flow prevention and treatment engineering design.

[0025] Based on the above landslide debris flow vertical impact force calculation method, the application further provides a design method of collapse landslide blocking and energy dissipation pile array, which first solves the design problem of energy dissipation pile single body flexural deformation stability parameters. The technical scheme is as follows:

[0026] The collapse landslide blocking and energy dissipation pile array design method realized by the above landslide debris flow vertical impact force distribution calculation method has the characteristics that:

[0027] Step S1, collapse landslide blocking and energy dissipation pile array engineering site investigation, obtaining basic investigation data, the basic investigation data including the landslide hidden danger data, blocking and energy dissipation pile array engineering data, using the basic investigation data to determine the design pile array position A of the blocking and energy dissipation pile array, and the energy dissipation pile single body calculation section data;

[0028] Step S2, using the method of claim 1 to calculate the vertical impact force P of the debris flow on the blocking and energy dissipation pile array (y) , the impact position A' is the design pile array position A, and the impact calculation point o is determined by the energy dissipation pile single body calculation section data;

[0029] Step S3, blocking and energy dissipation pile array impact resistance stability checking

[0030] For each energy dissipation pile single body calculation section, the impact force is calculated according to formula 3, formula 4 and formula 5 respectively

[0031] P (y) The flexural deformation of the energy dissipation pile single body under the condition of

[0032]

[0033]

[0034] ω (y) =ω (y)i +ω′ (y)i Formula 5

[0035] In formula 3 and formula 4, ω (y)i The flexural deformation of the energy dissipation pile single body i-th calculation section under uniform load, m,

[0036] ω′ (y)i The flexural deformation of the energy dissipation pile single body i-th calculation section under triangular load, m,

[0037] q1, q2 - are the uniformly distributed load and the triangularly distributed load, respectively, P (y) decomposition impact force, unit: KN / m, according to P (y) determined according to the prior art,

[0038] y has the same meaning as formula 1,

[0039] h i - the calculation section length of the energy-dissipation pile monomer, m, determined according to the basic survey data,

[0040] E - the elastic modulus of the steel material of the energy-dissipation pile monomer, kN·m 2 , determined according to the basic survey data,

[0041] I - the section moment of inertia of the energy-dissipation pile monomer, m 4 , determined according to the basic survey data,

[0042] C1, C2, B1, B2 - arbitrary constants, determined according to the boundary conditions of the calculation section,

[0043] ω (y) - the maximum flexural deformation of the energy-dissipation pile monomer under the vertical impact force P (y) of the debris flow;

[0044] Step S4, according to the steel structure impact-resistant safety performance design specification, the flexural deformation stability parameter design of the energy-dissipation pile monomer is completed.

[0045] The design method of the collapse landslide blocking energy-dissipation pile array of the application is an extension of the above-mentioned landslide debris flow vertical impact force distribution measurement method, which is used for the flexural deformation stability parameter design of the energy-dissipation pile monomer. According to the technical scheme of the collapse landslide blocking energy-dissipation pile array, the energy-dissipation pile array includes energy-dissipation pile monomers arranged in staggered rows, the anchoring section of the energy-dissipation pile monomer is buried below the ground surface, the free section of the energy-dissipation pile monomer is exposed above the ground surface, and the energy-dissipation pile monomer generally adopts a steel pipe pile or a concrete pile. The type of the energy-dissipation pile monomer is determined according to the resource allocation of the specific disaster point. Therefore, the energy-dissipation pile exposed above the ground is simplified as a cantilever beam, which is subjected to the impact of the debris flow and generates a bending resistance (equal in size and opposite in direction to the impact force of the debris flow on the energy-dissipation pile). On the basis of solving the problem of measuring the vertical impact force of the landslide debris flow, according to the principle of material mechanics ultimate bearing capacity, the relationship between the deflection of the energy-dissipation pile monomer and the impact force is established, and then the impact-resistant stability of the energy-dissipation pile monomer can be calculated. The key problem is to measure the bending moment distribution on the cantilever beam (i.e. the free section of the energy-dissipation pile monomer). The cantilever beam is divided into N calculation sections, and the deflection and load at the midpoint of each calculation section are taken as the average deflection and load of the section. The impact force P (y) of the debris flow on each section is simplified as a linear distribution Figure 1The impact force diagram of the cantilever beam by the debris flow is impacted and can be decomposed into a rectangular load (simplified as a uniformly distributed load calculation) impact force q1 component and a triangularly distributed load impact force q2 component, and each component establishes a y-axis starting from the ground. For any ith segment, the bending moment calculation expressions under the action of the uniformly distributed load and the triangular load are established as formula 3-1 and formula 4-1, respectively, and the beam deflection differential equations under the action of the uniformly distributed load and the triangular load are integrated by combining the beam deflection differential equations, respectively, to obtain the deflection equations of the ith calculation segment under the action of the uniformly distributed load and the triangular load, formula 3 and formula 4. In formula 3 and formula 4, C1, C2 and B1, B2 are arbitrary constants, which are determined by the boundary conditions of each calculation segment. For example, for the first calculation segment (h1), the rotation angle and the deflection at the ground are both 0 when y=0, and the boundary conditions are (y=0, θ=0; y=0, ω=0).

[0046]

[0047]

[0048] According to the material and size parameters of the designed energy dissipation pile unit, the deflection ω of each point on the free section can be obtained by applying the above calculation method (y) , and the stability parameter design of the deflection deformation of the energy dissipation pile unit can be completed according to the general engineering design specification.

[0049] The design method of the collapse landslide blocking and energy dissipation pile array can be further expanded to solve the problem of calculating the design energy dissipation Q of the collapse landslide blocking and energy dissipation pile array. The design energy dissipation Q refers to the existence of a protective target (such as a building) that cannot be impacted by the debris flow in the movement path of the debris flow in the landslide disaster prevention engineering, and the protective target is the safety protection site C. By designing the blocking and energy dissipation pile array in the movement path of the debris flow, the purpose is to make the debris flow only move to a certain place between the design pile array site A and the safety protection site C after impacting the blocking and energy dissipation pile array due to energy conversion and dissipation. The place is the design accumulation site B, which is a site upstream of the safety protection site C in the movement path of the debris flow. Therefore, there is a design energy dissipation Q of the blocking and energy dissipation pile array that needs to be calculated according to the site conditions. To achieve this goal, in step S1 above, the basic investigation data provide the safety protection site C data and the design pile array site A (i.e., the collapse landslide blocking and energy dissipation pile array arrangement region selected in the previous work in CN111809537A), and the basic investigation data can determine the design accumulation site B after the debris flow impacts the blocking and energy dissipation pile array. Further, after checking the bending design performance of the energy dissipation pile unit, the design energy dissipation Q parameter of the blocking and energy dissipation pile array is designed according to formula 6,

[0050] Q=Mgf·L-MgΔz1 Formula 6

[0051] In formula 5, Q is the design energy dissipation of the slope blocking and energy dissipation pile array (J), M is the total mass of the debris flow (kg), which is determined by the basic investigation data; g is the gravity acceleration constant (m / s2 f—Equivalent friction coefficient of debris flow (unitless), determined by basic survey data; L and Δz1—the horizontal and vertical distances (m) from the designed accumulation position B to the safety protection position C, respectively, determined in step S1.

[0052] Furthermore, the design of the number of energy dissipation pile array parameters can be completed. Under the premise that the individual energy dissipation piles meet the bending deformation conditions for debris flow impact, the total energy dissipation of a single energy dissipation pile theoretically includes two parts: first, the bending deformation of the energy dissipation pile itself consumes the impact kinetic energy, which is then dissipated by the bending reaction force P′. (y) With deformation deflection ω (y) Confirmed; secondly, the bending reaction force P′ (y) The continuous work done during the impact process consumes the impact kinetic energy, and the impact force P of the debris flow on the energy dissipation pile is generated. (y) The relative motion distance d between the two is determined. Therefore, calculating and determining the flexural deformation of the energy dissipation pile and the magnitude of the work done by the bending reaction force of the energy dissipation pile is crucial. The specific scheme is as follows: First, calculate the energy dissipation Q′ of a single energy dissipation pile according to Equations 7 to 9, and then calculate the total number of piles N of the retaining energy dissipation pile array according to Equation 10.

[0053]

[0054] P′ (y) =P (y) Formula 8

[0055]

[0056] In Equations 7 to 9, Q′—energy dissipation of a single energy dissipation pile (J); h—length of the free section of a single energy dissipation pile (m), determined by basic survey data; P′ (y) —Bending reaction force of a single energy dissipation pile (KN); ω (y) The meaning is the same as in equation 5; the meaning of y is the same as in equation 1; P (y) The meaning is the same as in equation 2; d—P′ (y) Distance of action (m); V—total volume of debris flow (m³) 3 ), the basic survey data is determined; b′, h′ — respectively the width and depth (m) of the debris flow to the designed pile position A, the basic survey data is determined.

[0057]

[0058] In Equation 10, N represents the total number of piles in the energy dissipation pile array.

[0059] In cases where energy dissipation protection is only needed for debris flows, it is sufficient to arrange N energy dissipation piles in a staggered pattern at the designed pile array location A, according to the terrain conditions. The arrangement of the energy dissipation piles does not affect the achievement of the energy dissipation target of the pile array.

[0060] In the landslide disaster, if the landslide hazard data includes rockfall hazard, the damage of landslide body to the prevention and control engineering needs to consider the impact of rockfall in addition to the impact of debris flow. To better solve this problem, the above design method can be further optimized:

[0061] First, calculate the energy dissipation pile single body flexural deformation stability parameter design under the condition of rockfall impact. This step can consider the rockfall as a concentrated load, and the deformation calculation formula of cantilever beam is established according to the method of calculating the flexural deformation of cantilever beam, and the flexural deformation of single pile under rockfall impact is directly calculated to check the flexural deformation stability parameter design of single energy dissipation pile. After checking that the safety condition is met, the total row number n of the blocking energy dissipation pile array is calculated according to formula 11, and finally the total pile number N and the total row number n are used to complete the pile array design.

[0062]

[0063] In formula 11, n is the total row number of the blocking energy dissipation pile array; The rockfall impact force acting on y0, y0 is determined according to the diameter of the rockfall; u is the flexural deformation (m) of the energy dissipation pile under rockfall impact, which is determined in step S3; E k The kinetic energy (J) of the rockfall moving to the design pile array position A is determined in step S1.

[0064] In the method of the application, the field investigation includes various geological survey, mapping, measurement, simulation experiment test, historical disaster record acquisition and experience data acquisition with reference effect at the disaster site or disaster hidden danger site of the geological disaster prevention and control engineering. The landslide hazard data refers to various data related to landslide disasters that can be obtained by field investigation combined with existing technologies. The blocking energy dissipation pile array engineering data refers to various data, standards and specifications required for the design and construction of the blocking energy dissipation pile array.

[0065] Compared with the prior art, the beneficial effects of the application are: the applicant's prior art provides a collapse landslide blocking energy dissipation pile array. As a kind of geological disaster prevention and control engineering structure, the pile array utilizes the different types of deformation of energy dissipation pile single body and foundation soil body when the structure is subjected to different magnitude rockfall impact to consume the kinetic energy of rockfall, thereby effectively reducing the harm of rockfall and the consequences and losses caused by rockfall. In the technical solution of the application, the applicant improves the design method of the prevention and control engineering structure, so that it can realize the energy dissipation and disaster reduction of landslide debris flow. To solve this technical problem, the application first provides a method for calculating the vertical impact force of landslide debris flow, which can solve the problem of vertical impact force P (y)Distribution. The method for calculating the vertical impact force distribution of landslide debris flows in this invention can be applied to the design of landslide and landslide debris flow protection engineering, providing parameters for the impact force of landslide debris flows. The design method for retaining and dissipating pile arrays in landslides provided by this invention simplifies the energy dissipating piles exposed above ground as cantilever beams, which generate bending reaction forces when subjected to debris flow impacts. These bending reaction forces continuously dissipate the impact kinetic energy of the debris flow. The key to the retaining and dissipating pile array design method of this invention is: based on the comprehensive analysis of the movement characteristics of landslide debris flows and the calculation of the magnitude and distribution of the impact force on the energy dissipating piles, further derive parameters such as the impact force action time and distance, and solve the problems of designing the bending deformation stability parameters of individual energy dissipating piles, the energy dissipation Q parameter of the retaining and dissipating pile array design, and the calculation of the number of retaining and dissipating pile arrays in a hierarchical manner. The design method provides a more scientific and comprehensive solution for the energy dissipation design of retaining and dissipating pile arrays to cope with the impact damage of rolling stones and debris flows in landslide disasters. The design method of this invention also continues the advantages of prior technical solutions, namely, taking the maximum energy dissipation of a single energy dissipation pile as the core calculation unit, so that the calculation method can effectively match the highly modular structure of the entire retaining energy dissipation pile array, resulting in low maintenance costs in the later stage. Attached Figure Description

[0066] Figure 1 Impact force diagram of debris flow on a cantilever beam.

[0067] Figure 2 This is a schematic diagram of the longitudinal profile of the landslide disaster site. Detailed Implementation

[0068] The preferred embodiments of the present invention will now be further described with reference to the accompanying drawings.

[0069] Example 1

[0070] like Figure 2 As shown, the method of this invention is used to design a landslide retaining and energy dissipation pile array for a potential slope.

[0071] A debris flow disaster site on a highway in Tibet has an overall slope of 26°. Investigations show the landslide is approximately 4.67 km long, with a maximum elevation difference of 860 m between its front and rear edges. The estimated mass of the landslide in the source area is approximately 2.75 × 10⁻⁶ m. 7 m 3 ~3.58×10 7 m 3 The potential landslide hazard point poses a great threat to downstream transportation and infrastructure. It is planned to design a landslide retaining and energy dissipation pile array as a landslide disaster prevention measure.

[0072] 1. Conduct on-site investigations to obtain basic survey data.

[0073] Figure 2Figure 1 is a longitudinal section view of a landslide disaster point. Basic survey data required for engineering design is obtained through field investigation. The basic survey data includes two parts:

[0074] (1) Landslide hazard data

[0075] The height difference (H) between the front and back edges of the landslide body is 860 m, and the height difference between the outlet section of the landslide body source area and the slope toe is about 70 m. The nearest protective object downstream of the disaster point is a village about 300 m in front of the predicted accumulation body of the landslide.

[0076] The landslide body mainly contains clay and gravel, and the diameter of the gravel pieces ranges from 5 cm to 300 cm. The density of the landslide debris flow is p = 2800 kg / m 3 , the total mass of the debris flow is M = 7.7 x 10 10 kg, and the total volume of the debris flow is V = 2.75 x 10 7 m 3 . The destructive rolling stone to be prevented has a diameter of 300 cm, and according to the existing technology, the mass of the rolling stone is 39564 kg, the impact force when moving to the design pile array position A is 1.28 x 10 5 kN, and the kinetic energy E k = 2.56 x 10 7 J.

[0077] According to the characteristic parameters of the disaster point, the equivalent friction coefficient of the landslide body movement path is f = 0.08, and the dynamic pressure coefficient of the movement process is a = 3.0.

[0078] According to the energy conservation law, the inflow rate of the debris flow impacting the design pile array position A (see below) is 40 m / s, the outflow rate is 32 m / s, and the average flow rate u a = 36 m / s during the impact process.

[0079] Based on the basic survey data and the terrain conditions at the design pile array position A, the accumulation thickness of the debris flow moving to the design pile array position A is calculated as δ = 3 m, the width is b' = 500 m, and the depth is h' = 3 m.

[0080] (2) Engineering data of the blocking and energy dissipation pile array

[0081] According to the village area planning as a safety protection site C, and according to the movement path of the landslide debris flow and the surrounding terrain environmental conditions, the outlet of the landslide debris flow source area is selected as the design pile array position A for arranging the energy dissipation piles, and the height difference between the design pile array position A and the slope toe is about 70 m. At the same time, the design accumulation site B between the design pile array position A and the safety protection site C is selected. The horizontal distance between the design accumulation site B and the safety protection site C is L = 10 m, and the vertical distance is Δz1 = 0 m.

[0082] The energy dissipation pile array selects reinforced concrete pouring energy dissipation pile, the grade of reinforced concrete energy dissipation pile is selected according to the actual engineering, and mainly through the deflection equation of the beam to check and calculate, the single energy dissipation pile side length d0=1.0m. According to the concrete construction specification, the structure parameters of the energy dissipation pile are determined, and the C20 concrete is selected to build the energy dissipation pile array. The elastic modulus of the single energy dissipation pile steel E=2.55×10 7 kN / m 2 , the cross-sectional moment of inertia I=0.0833m 4 , the free section length is h=3m. According to the structure design specification in civil engineering, the range of the free section (beam) deflection-span ratio is limited to The value in the embodiment is calculated, and h=3m is substituted, so the maximum allowable deflection of the free section (beam) [u]=12mm.

[0083] 2, calculate the vertical impact force P of the debris flow on the blocking energy dissipation pile array (y)

[0084] The free section of the energy dissipation pile is divided into 10 calculation sections, and the length of each calculation section is 0.3m. The coordinates of the impact calculation point o(x,y) of each calculation section are the coordinates of the center of the calculation section. For each calculation section, ua, y, δ, α, ρ are substituted into formula 1 and formula 2 to calculate the tangential velocity v (y) and the impact force P (y) of the debris flow of each calculation section, see table 1.

[0085] Table 1 calculation table of vertical impact force of debris flow on blocking energy dissipation pile array

[0086] Computes segment point y coordinate (m) tangential movement speed v (y) ]]> Impact force P (y) (kN) 0 0 0.0 0.3 8.77 627.435 0.6 17.07 1722.525 0.9 24.86 3040.466 1.2 32.11 4455.001 1.5 38.79 5867.636 1.8 44.82 7192.241 2.1 50.14 8349.506 2.4 54.63 9264.362 2.7 58.10 9864.59 3 60 10080

[0087] 3, impact stability calculation of blocking energy dissipation pile array

[0088] 3.1 anti-debris flow impact stability calculation

[0089] For the first calculation section, the calculation parameters are substituted into formula 3, formula 4 and formula 5 to calculate the ω (y)i , ω′ (y)i of each calculation section and the ω (y) of the single energy dissipation pile. Taking the first calculation section 0m-0.3m as an example: at both ends of the first calculation section, y=0, the impact force P=0, and y=0.3m, the impact force P=627.44kN, so q1=0 and q2=627.44kN. According to formula 3 and formula 4, the deflection deformation ω (y)i and ω′ (y)i of the first calculation section are calculated respectively, ω (y＝0.3m)= 0.0028mm. After calculating the deflection deformation of the following 9 calculation sections, the anti-debris flow impact stability checking results are shown in Table 2.

[0090] Table 2 Anti-debris flow impact stability checking data

[0091]

[0092]

[0093] Table 2 shows that the maximum deformation ω of the energy dissipation pile single body (y) = 6mm, which is less than the allowable deflection [u] = 12mm of the energy dissipation pile single body. According to the impact safety performance design specification for steel structures, the impact instability review meets the requirements.

[0094] 3.2 Anti-rolling stone impact stability checking

[0095] According to the method of calculating the deflection deformation of the cantilever beam in material mechanics, the deformation calculation formula of the cantilever beam and the deflection deformation calculation formula of the cantilever beam are established, including the energy dissipation deformation calculation formula of the cantilever beam (formula 11), the deflection deformation calculation formula of the cantilever beam (formula 12). In formula 12, u is the deflection deformation of the energy dissipation pile (m). According to the deformation stability parameters of the energy dissipation pile, the maximum deflection deformation u0 of the energy dissipation pile is determined as 6mm, and the maximum load borne by the energy dissipation pile under the deflection deformation is The maximum energy dissipation of the energy dissipation pile single body is obtained in turn.

[0096]

[0097] According to formula 11, the number of rows of energy dissipation piles required to dissipate the kinetic energy of the rolling stone under the impact of the debris flow and the rolling stone is 4 rows.

[0098] 4. Deflection deformation stability parameter design of energy dissipation pile single body

[0099] According to the above checking results, the main parameters of the deflection deformation stability of the energy dissipation pile single body are ω (y) : limited within the allowable deflection [u] range of the energy dissipation pile single body, E k : kinetic energy of the rolling stone, u0, When the single energy dissipation pile is checked under the impact of the rolling stone, the number of rows n of energy dissipation piles required for the stability of the energy dissipation pile array is determined.

[0100] 5. Design of design energy dissipation Q parameter of blocking energy dissipation pile array

[0101] The total mass M of the debris flow, g = 9.8m / s 2 , the equivalent friction coefficient f of the debris flow movement process, the horizontal distance L from the design accumulation position B to the safety protection position C, and the vertical distance Δz1 are substituted into formula 6 to calculate the design energy dissipation Q of the blocking energy dissipation pile array = 3.46 × 1012 J.

[0102] 6、Calculate the energy dissipation Q' of the single energy dissipation pile

[0103] The length h of the single energy dissipation pile, the bending resistance P' of the single energy dissipation pile, the maximum deformation ω of the single energy dissipation pile, the impact force P of the debris flow, the action distance d, the width b' and the depth h' of the debris flow flowing to the designed pile array position A are substituted into formula 7, formula 8 and formula 9 to calculate the energy dissipation Q' of the single energy dissipation pile (y) (y) (y) (y) 11 J.

[0104] 7、Determine the number of barrier energy dissipation pile arrays

[0105] The designed energy dissipation Q of the barrier energy dissipation pile array and the energy dissipation Q' of the single energy dissipation pile are substituted into formula 10, the impact force P of the debris flow, the deflection deformation M of the single energy dissipation pile under the impact of the rolling stone, and the kinetic energy E of the rolling stone moving to the designed pile array position A are substituted into formula 11 to calculate the total number of piles N of the barrier energy dissipation pile array (y) (y) k

[0106] The single energy dissipation piles are arranged in staggered rows (in the shape of a plum blossom). In this embodiment, the pile spacing of each row is 1 m, and 6 energy dissipation piles are arranged in each row. The spacing of the energy dissipation piles in each row is designed to be 1 m according to the terrain conditions.​​​​​​​

Claims

1. A method for calculating the vertical impact force of a landslide debris flow, for calculating the vertical impact force of the debris flow on the impact site A' P (y) distribution; Characterized in that: First, the site investigation of the collapse and landslide hazard, obtain landslide hazard data; Secondly, the landslide debris flow at the impact calculation point is calculated according to Equation 1. o ( X, y tangential velocity v (y) The impact calculation point o These are different height points on the impact site A′. Formula 1 In Equation 1, v (y) - Landslide debris flow at impact calculation point o The tangential velocity, m / s; u a - debris flow impact process average flow velocity, m / s, determined from landslide hazard data; y - impact calculation point o height, m, determined from landslide hazard data; Delta - the thickness, m, of the accumulation of the flow of debris moving to the impact site A', determined from the landslide hazard data; Again, the vertical impact force of the debris flow on the impact calculation point is calculated according to formula 2 o P (y) ,​ Formula 2 In Equation 2, P (y) - Debris flow to calculation point o′ The vertical impact force, kN; α - dynamic pressure coefficient of the debris flow motion process, unitless, determined from the landslide hazard data; Rho - debris flow density, kg / m 3 determined from landslide hazard data.

2. The collapse and landslide blocking energy dissipation pile array design method realized by the landslide debris flow vertical impact force calculation method of claim 1, characterized in that: Step S1, the engineering site investigation of the collapse and landslide blocking energy dissipation pile array, obtaining basic investigation data; The basic investigation data includes the landslide hazard data, the blocking energy dissipation pile array engineering data, and the design pile array position A of the blocking energy dissipation pile array is determined by using the basic investigation data, and the energy dissipation pile single calculation section data; Step S2, the vertical impact force of the debris flow on the barrier energy dissipation pile array is calculated by the method of claim 1 P (y) The impact point A' is the design pile array point A, and the impact calculation point o is determined by the calculation section data of the energy dissipation pile monomer. Step S3, impact stability checking of the blocking energy dissipation pile array; For each energy-dissipation pile monomer calculation section, the impact force is calculated according to formula 3, formula 4 and formula 5 respectively P (y) The flexural deformation of the energy-dissipation pile monomer under the condition Formula 3 Formula 4 Formula 5 in formulae 3 to 5, Omega (y)i - deflection of the single energy-dissipating pile under uniformly distributed load i flexural deformation of the calculation section, m; ω' (y)i - single energy-dissipating pile under triangularly distributed load i flexural deformation of the calculation section, m; q 1、 q 2 - respectively uniform load and triangular load distribution under P (y) decomposition of the impact force, kN, according to P (y) determined by calculation according to the prior art; y the same meaning as formula 1; h i - Energy dissipating pile monoliths i The segment length, m, is determined from basic survey data; E - Elastic modulus of the monolithic steel of the energy-dissipating pile, kN / m 2 Determined from the basic survey data; I - the inertia moment of the monolithic section of the energy-dissipating pile, m 4 determined from the basic survey data; C 1. C 2. B 1. B 2 - Arbitrary constant, from the first i The boundary conditions of the calculation segment are determined; Omega (y) - maximum flexural deformation of the energy dissipating pile monolith under vertical impact force of the debris flow, m; and P (y) maximum flexural deformation of the energy dissipating pile monolith under vertical impact force of the debris flow, m; and Step S4, completing the energy dissipation pile single flexural deformation stability parameter design according to the steel structure impact safety performance design specification.

3. The design method of claim 2, characterized in that: In step S1, the design accumulation position B after the impact of the blocking energy dissipation pile array by the debris flow is determined by using the basic investigation data; Further comprising step S5, designing energy dissipation amount of the fender energy dissipation pile array Q Parameters, The design energy dissipation of the collapse and landslide blocking and energy dissipation pile array is calculated according to the formula 6 Q , Formula 6 In formula 6, Q - Design of energy dissipation of slope barrier energy dissipation pile array, J; M - total mass of the debris flow, kg, determined from basic survey data; g - gravitational acceleration constant, m / s 2 ; f - equivalent friction coefficient of the debris flow motion process, unitless, determined from basic investigation data; L , Δ z 1 - are the horizontal and vertical distances, m, respectively, of the design pile position B to the safety shield position C, determined by step S1.

4. The method of designing according to claim 3, characterized in that: Further comprising step S6, designing the number of parameters of the fender energy dissipation pile array, and calculating the energy dissipation amount of the energy dissipation pile monomer according to formula 7, formula 8 and formula 9 Q ′, Formula 7 Formula 8 Formula 9 In formulae 7 to 9, Q′ - energy dissipation of the monolith, J; h - length of the free section of the energy-dissipating pile monolith, m, determined from basic survey data; P′ (y) - Bending resistance of the energy-dissipating pile monomer, KN; Omega (y) as defined in formula 5; y the same meaning as formula 1; P (y) as defined in formula 2; d - P′ (y) Range, m; V - total volume of landslide, m 3 determined from basic survey data; b′ , h′ - width and depth of the debris flow flow to the designed pile array site A, m, determined by basic investigation data, respectively; The total number of piles of the array of fender piles is calculated according to formula 10 N , Formula 10 In formula 10, N - Total number of piles of the array of fender piles.

5. The method of designing according to claim 4, characterized in that: If the landslide hazard data includes rockfall impact, The step S3 further includes checking the energy dissipation pile single flexural deformation stability parameter design under the rockfall impact condition; The step S6 further comprises calculating the total number of rows of the array of fender energy dissipating piles according to the formula 11 n , Formula 11 In formula 11, n - total number of rows of the array of fender piles; P (y0) - acting on y the impact force of the rolling stone at 0, y 0 is determined from the rolling stone diameter; u - the single deflection of the energy-dissipating pile under the rock impact, m, determined in step S3; E k － The kinetic energy, J, of the rolling stone moving to the design pile location A is determined by step S1.

6. The application of the landslide debris flow vertical impact force calculation method of claim 1 in the design of landslide prevention engineering or landslide debris flow prevention engineering.

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