A data processing method for railway bridge pile foundation suitable for any geological conditions

Abstract

The application discloses a kind of railway bridge pile foundation data processing methods suitable for arbitrary geological conditions, comprising the following steps: induction is carried out to special geology, and four basic special geologies are obtained;According to seasonal freezing depth line, permafrost upper limit depth line, neutral point depth line, sharp layer depth line, the action area of various special geologies is divided;Only one special geology exists in the non-intersecting area obtained by division, and the calculation parameters and calculation steps of the non-intersecting area are given;In the intersecting area obtained by division, there is a comprehensive action of multiple special geologies, and the calculation parameters and calculation steps of the coupled intersecting area are given;The above calculation parameters and calculation steps are substituted into the general design of railway bridge pile foundation, and the numerical calculation of bridge pile foundation under arbitrary geological conditions is completed.The application can solve the problem that the calculation efficiency and accuracy of pile foundation under special geology in the field of transportation cannot be satisfied simultaneously, and a high-precision and high-efficiency calculation method is given.

Description

Technical Field

[0001] This invention belongs to the field of railway bridge engineering technology in the transportation industry, and specifically relates to a method for processing railway bridge pile foundation data applicable to any geological conditions. Background Technology

[0002] my country's climate varies greatly, and its vast territory means that railways, as a vital mode of transportation, traverse rivers, deserts, mountains, and snowfields, enduring the challenges of diverse and complex geological environments. Bridge pile foundations are one of the main structural forms of railways, and calculations under complex geological conditions face three major challenges: first, the concise guiding principles in railway specifications cannot be directly translated into theoretical algorithms for practical engineering applications; second, the low computational efficiency of detailed modeling prevents its mass application in large-scale railway designs; and third, conservatively considering the impact of various special geological environments leads to engineering waste. Therefore, during large-scale railway construction, only through independent innovation, researching data processing methods for railway bridge pile foundations under arbitrary geological conditions, and combining them with existing pile foundation calculation programs, can current design needs be met. Summary of the Invention

[0003] This invention is proposed to solve the problems existing in the prior art, and its purpose is to provide a data processing method for railway bridge pile foundations applicable to any geological conditions.

[0004] The technical solution of this invention is: a data processing method for railway bridge pile foundations applicable to any geological conditions, comprising the following steps:

[0005] A. By summarizing the special geological features, four basic types of special geological features were identified;

[0006] B. Based on the seasonal freezing depth line, the upper limit of permafrost depth line, the neutral point depth line, and the steep layer depth line, the areas affected by various special geological conditions are delineated.

[0007] C. In the non-overlapping regions obtained from the division, there is only one special geological effect. The calculation parameters and calculation steps for each non-overlapping region are given by category.

[0008] D. In the intersecting regions obtained by division, there are multiple special geological complexes. Considering the geological coupling effect, give the calculation parameters and calculation steps after coupling of the intersecting regions;

[0009] E. Substitute the calculation parameters and steps obtained in steps C and D into the general design of railway bridge pile foundations to complete the numerical calculation of bridge pile foundations under any geological conditions.

[0010] Furthermore, step A summarizes the special geological features, resulting in four basic types of special geological features: static water, negative skin friction, expansive soil, and earthquake-liquefied soil.

[0011] Furthermore, step B delineates various special geological zones based on the seasonal freezing depth line, the upper limit of permafrost depth line, the neutral point depth line, and the abrupt layer depth line. The seasonal freezing depth line and the upper limit of permafrost depth line are the boundaries between ice, liquid water, and frozen soil; the neutral point depth line is the boundary between negative and positive skin friction; the abrupt layer depth line is the boundary between expansive and non-expansive soils; and earthquake-liquefied soils are delineated according to soil layers.

[0012] Furthermore, in the non-overlapping regions obtained from step C, only one specific geological effect exists. The calculation parameters and steps for each non-overlapping region are categorized and provided, including modifications to the soil layer calculation parameters. The specific process is as follows:

[0013] Firstly, the non-intersecting areas are filled with ice, so the calculation parameters and steps remain unchanged.

[0014] Secondly, in the non-intersecting areas, the water is in liquid state. When the pile bottom is permeable, the bulk density of the soil in the water is taken as the buoyant bulk density. When the pile bottom is impermeable, the bulk density of the soil in the water is taken as the saturated bulk density.

[0015] Third, in areas where there is no overlap, the soil is frozen soil, and the soil side friction, pile end friction, and foundation ratio coefficient are taken from the frozen soil specification values.

[0016] Fourth, the non-intersecting area has negative frictional resistance, and positive side frictional resistance is not considered;

[0017] Fifth, the non-intersecting area is expansive soil, and the pile side friction of the expansive soil above the abrupt layer depth is 0.

[0018] Furthermore, in the non-overlapping regions obtained from step C, only one special geological effect exists. The calculation parameters and steps for each non-overlapping region are categorized and provided. When the non-overlapping region contains seismically liquefiable soil, the modification of the soil layer calculation parameters is as follows:

[0019] First, calculate the liquefaction reduction factor for each layer of seismically liquefiable soil;

[0020] Then, the pile side friction, pile end friction, subgrade coefficient, and internal friction angle of earthquake-liquefiable soil must all be multiplied by the liquefaction reduction factor.

[0021] Finally, the allowable bearing capacity of the soil layer above the earthquake-liquefied soil is not modified.

[0022] Furthermore, in the cross regions obtained from step D, there are various special geological complexes. Considering the geological coupling effect, the calculation parameters and calculation steps after coupling of the cross regions are given. When considering the influence of the cross regions on the soil layer calculation parameters, the neutral point depth is determined first. Soil above the neutral point depth is characterized by negative skin friction; soil below the neutral point depth is characterized by different cases.

[0023] Furthermore, when the soil below the neutral point depth is also below the upper limit of permafrost depth, the pile side friction, pile end friction, and foundation ratio coefficient of this portion of soil shall be taken from the permafrost specification values. This portion of soil includes: negative skin friction, earthquake liquefaction soil, and expansive soil.

[0024] Furthermore, when the soil below the neutral point depth is also above the upper limit of permafrost depth, the calculation parameters for this portion of soil are determined according to the properties of general soil. This portion of soil does not include earthquake-liquefiable soil or expansive soil.

[0025] Furthermore, when the soil below the neutral point depth is also above the upper limit of permafrost depth, this portion of the soil is earthquake-liquefiable soil, and the soil's lateral friction, end friction, subgrade coefficient, and internal friction angle are all multiplied by the liquefaction reduction factor.

[0026] Furthermore, when the soil below the neutral point depth is above the upper limit of permafrost depth, and this portion of soil is expansive soil, and this portion of soil is above the abrupt layer depth, the side friction of this portion of soil is not considered.

[0027] The beneficial effects of this invention are as follows:

[0028] This invention proposes a data processing method for railway bridge pile foundations under arbitrary geological conditions by comparing and analyzing the influence of various special geological conditions on pile foundation calculations. This method is embedded in the pile foundation calculation process and applied to the design of large-scale railway bridges, enabling efficient, accurate, and batch calculations of pile foundations under complex geological conditions.

[0029] This invention addresses the problem that the calculation efficiency and accuracy of pile foundations under special geological conditions in the transportation field cannot be simultaneously satisfied. It provides a high-precision and high-efficiency calculation method, which is not only applicable to long-distance railway projects, but can also be extended to small and medium-sized projects such as highways, municipal works, and light rail. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method of the present invention;

[0031] Figure 2 This is a diagram showing the calculation parameters of the soil layers in the intersection area in this invention;

[0032] Figure 3 This is a diagram of the bridge pier pile foundation layout in Example 1 of this invention. Detailed Implementation

[0033] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0034] like Figures 1 to 3 As shown, a method for processing railway bridge pile foundation data applicable to any geological conditions includes the following steps:

[0035] A. By summarizing the special geological features, four basic types of special geological features were identified;

[0036] B. Based on the seasonal freezing depth line, the upper limit of permafrost depth line, the neutral point depth line, and the steep layer depth line, the areas affected by various special geological conditions are delineated.

[0037] C. In the non-overlapping regions obtained from the division, there is only one special geological effect. The calculation parameters and calculation steps for each non-overlapping region are given by category.

[0038] D. In the intersecting regions obtained by division, there are multiple special geological complexes. Considering the geological coupling effect, give the calculation parameters and calculation steps after coupling of the intersecting regions;

[0039] E. Substitute the calculation parameters and steps obtained in steps C and D into the general design of railway bridge pile foundations to complete the numerical calculation of bridge pile foundations under any geological conditions.

[0040] Furthermore, step A summarizes the special geological features, resulting in four basic types of special geological features: static water, negative skin friction, expansive soil, and earthquake-liquefied soil.

[0041] Furthermore, step B delineates various special geological zones based on the seasonal freezing depth line, the upper limit of permafrost depth line, the neutral point depth line, and the abrupt layer depth line. The seasonal freezing depth line and the upper limit of permafrost depth line are the boundaries between ice, liquid water, and frozen soil; the neutral point depth line is the boundary between negative and positive skin friction; the abrupt layer depth line is the boundary between expansive and non-expansive soils; and earthquake-liquefied soils are delineated according to soil layers.

[0042] Furthermore, in the non-overlapping regions obtained from step C, only one specific geological effect exists. The calculation parameters and steps for each non-overlapping region are categorized and provided, including modifications to the soil layer calculation parameters. The specific process is as follows:

[0043] Firstly, the non-intersecting areas are filled with ice, so the calculation parameters and steps remain unchanged.

[0044] Secondly, in the non-intersecting areas, the water is in liquid state. When the pile bottom is permeable, the bulk density of the soil in the water is taken as the buoyant bulk density. When the pile bottom is impermeable, the bulk density of the soil in the water is taken as the saturated bulk density.

[0045] Third, in areas where there is no overlap, the soil is frozen soil, and the soil side friction, pile end friction, and foundation ratio coefficient are taken from the frozen soil specification values.

[0046] Fourth, the non-intersecting area has negative frictional resistance, and positive side frictional resistance is not considered;

[0047] Fifth, the non-intersecting area is expansive soil, and the pile side friction of the expansive soil above the abrupt layer depth is 0.

[0048] Furthermore, in the non-overlapping regions obtained from step C, only one special geological effect exists. The calculation parameters and steps for each non-overlapping region are categorized and provided. When the non-overlapping region contains seismically liquefiable soil, the modification of the soil layer calculation parameters is as follows:

[0049] First, calculate the liquefaction reduction factor for each layer of seismically liquefiable soil;

[0050] Then, the pile side friction, pile end friction, subgrade coefficient, and internal friction angle of earthquake-liquefiable soil must all be multiplied by the liquefaction reduction factor.

[0051] Finally, the allowable bearing capacity of the soil layer above the earthquake-liquefied soil is not modified.

[0052] Furthermore, in the cross regions obtained from step D, there are various special geological complexes. Considering the geological coupling effect, the calculation parameters and calculation steps after coupling of the cross regions are given. When considering the influence of the cross regions on the soil layer calculation parameters, the neutral point depth is determined first. Soil above the neutral point depth is characterized by negative skin friction; soil below the neutral point depth is characterized by different cases.

[0053] Furthermore, when the soil below the neutral point depth is also below the upper limit of permafrost depth, the pile side friction, pile end friction, and foundation ratio coefficient of this portion of soil shall be taken from the permafrost specification values. This portion of soil includes: negative skin friction, earthquake liquefaction soil, and expansive soil.

[0054] Furthermore, when the soil below the neutral point depth is also above the upper limit of permafrost depth, the calculation parameters for this portion of soil are determined according to the properties of general soil. This portion of soil does not include earthquake-liquefiable soil or expansive soil.

[0055] Furthermore, when the soil below the neutral point depth is also above the upper limit of permafrost depth, this portion of the soil is earthquake-liquefiable soil, and the soil's lateral friction, end friction, subgrade coefficient, and internal friction angle are all multiplied by the liquefaction reduction factor.

[0056] Furthermore, when the soil below the neutral point depth is above the upper limit of permafrost depth, and this portion of soil is expansive soil, and this portion of soil is above the abrupt layer depth, the side friction of this portion of soil is not considered.

[0057] Specifically, the special geological features in step A mainly include: negative skin friction, collapsible loess, earthquake-induced liquefaction soil, frozen soil, frost pull-out force, expansive soil, red clay, saline soil, soft soil, karst, and mining subsidence areas.

[0058] The impact of certain geological conditions on pile foundations can be quantified in some cases by modifying soil layer calculation parameters, such as karst and mined-out areas. Others are already considered in general pile foundation designs, such as the stress calculation of underlying layers in soft soil. The remaining special geological conditions require additional input data or calculation steps in the general pile foundation design. By comparing and analyzing their relationships, four basic types of special geological conditions are identified: hydrostatic, negative skin friction, expansive soil, and earthquake-liquefiable soil. Calculations for other special geological conditions can be categorized into these four basic types.

[0059] Specifically, step C addresses the non-overlapping areas where only one specific geological condition exists. It categorizes and provides calculation parameters and steps for each area. The impact of each area on the pile foundation is mainly addressed from three aspects: the impact on soil layer calculation parameters, the impact on external forces at the pile top, and the impact on pile foundation settlement.

[0060] The calculation parameters for the soil layers have already been discussed. The following discussion will focus on the influence of external forces at the pile top and their impact on pile settlement.

[0061] The specific process of the influence of external forces on the pile top is as follows:

[0062] Firstly, the non-intersecting areas are filled with ice, generating an upward frost pull force, which is included in the weight of the ice above the top of the pier.

[0063] Secondly, if the non-intersecting area contains liquid water, the weight of the water above the pile cap is not included when the pile bottom is permeable, but is included when the pile bottom is impermeable.

[0064] Third, the non-intersecting areas are permafrost, so there is no impact.

[0065] Fourth, the non-intersecting area is the negative skin friction. The calculated negative skin friction is used as the external force at the pile top. The calculation of negative skin friction adopts two methods: negative skin friction coefficient and negative skin friction value. The negative skin friction of self-weight collapsible loess is a fixed value and the negative skin friction value is used. The negative skin friction of other soils = negative skin friction coefficient × vertical stress of soil.

[0066] Fifth, the non-intersecting areas are filled with expansive soil, which generates upward expansive force.

[0067] Sixth, the non-intersecting areas are composed of earthquake-liquefied soil, which has no impact.

[0068] The impact on pile foundation settlement is as follows:

[0069] Firstly, the non-intersecting areas are covered by ice, and the ice layer is generally above the bottom of the piles, so it has no direct impact.

[0070] Secondly, the non-intersecting areas are filled with liquid water, so there is no direct impact.

[0071] Thirdly, the non-intersecting areas are frozen soil, and the post-construction settlement is 0.

[0072] Fourth, the non-intersecting area is a negative skin friction. The negative skin friction is included in the dead load and participates in the calculation of pile foundation settlement. If the pile foundation is located in a collapsible loess site, the settlement shall be handled in accordance with the relevant provisions of the "Code for Building Construction in Collapsible Loess Area".

[0073] Fifth, the non-intersecting areas are filled with expansive soil, which is generally above the pile bottom and has no direct impact.

[0074] Sixth, the non-intersecting areas are composed of earthquake-liquefied soil, which has no impact.

[0075] Example 1

[0076] In a certain project, the pile foundation of a bridge pier uses 12 piles with a diameter of 1m. The ground elevation is -0.271m, the bottom elevation of the pile cap is -2.908m, and the water level elevation is -15.271m. Specific dimensions are as follows: Figure 3 .

[0077] Representative values ​​of the external forces on the pier cap were selected from the main force, main force + additional force, main force + special load, and main force + seismic load, as shown in Table 1.

[0078] Table 1 External Forces on the Top of a Bridge Pier Abutment

[0079]

[0080] Below the ground, there are mainly 7 soil layers. The geological parameters of each soil layer are shown in Table 2. There are special geological features in the strata. The first layer is cohesive soil with expansive soil characteristics. The steep layer is 4m below the ground. The second layer is silt, which is an earthquake liquefaction layer with a liquefaction reduction factor of 0.33. Considering that the groundwater level will drop during construction, the first two soil layers will settle and have negative skin friction. The negative skin friction coefficient is taken as 0.3, and the neutral point depth is 15m below the ground.

[0081] Table 2 Geological parameters of a bridge pile foundation

[0082]

[0083] The above-mentioned special geological conditions involve the effects of negative skin friction, liquefiable soil, expansive soil, and groundwater. The calculations performed using the method described in this paper are shown in Table 3. As can be seen from the table, after considering the combined effects of these special geological conditions, the vertical pile length, pier top displacement, pile reinforcement area, and pile shear stress have all increased compared to before.

[0084] Table 3 Comparison of Calculation Results for Pile Foundations Considering Special Geological Influences

[0085]

[0086] This invention proposes a data processing method for railway bridge pile foundations under arbitrary geological conditions by comparing and analyzing the influence of various special geological conditions on pile foundation calculations. This method is embedded in the pile foundation calculation process and applied to the design of large-scale railway bridges, enabling efficient, accurate, and batch calculations of pile foundations under complex geological conditions.

[0087] This invention addresses the problem that the calculation efficiency and accuracy of pile foundations under special geological conditions in the transportation field cannot be simultaneously satisfied. It provides a high-precision and high-efficiency calculation method, which is not only applicable to long-distance railway projects, but can also be extended to small and medium-sized projects such as highways, municipal works, and light rail.

Claims

1. A method for processing railway bridge pile foundation data applicable to any geological conditions, characterized in that: Includes the following steps: (A) By summarizing the special geological features, four basic special geological features were identified; The four basic special geological types are still water, negative skin friction, expansive soil, and earthquake-liquefiable soil. (B) Based on the seasonal freezing depth line, the upper limit of permafrost depth line, the neutral point depth line, and the steep layer depth line, the areas affected by various special geological conditions are delineated. Based on the seasonal freezing depth line and the upper limit of permafrost depth line, still water is divided into ice, liquid water and permafrost. (C) In the non-overlapping regions obtained by division, there is only one special geological effect. The calculation parameters and calculation steps for each non-overlapping region are given by category. (D) In ​​the intersecting regions obtained by division, there are a variety of special geological complexes. Considering the geological coupling effect, give the calculation parameters and calculation steps after coupling of the intersecting regions; (E) Substitute the calculation parameters and calculation steps obtained in steps (C) and (D) into the general design of railway bridge pile foundations to complete the numerical calculation of bridge pile foundations under any geological conditions; In the non-overlapping regions obtained in step (C), only one special geological effect exists. The calculation parameters and steps for each non-overlapping region are categorized and given, including modifications to the soil layer calculation parameters. The specific process is as follows: Firstly, the non-intersecting areas are filled with ice, so the calculation parameters and steps remain unchanged. Secondly, in the non-intersecting areas, the water is in liquid state. When the pile bottom is permeable, the bulk density of the soil in the water is taken as the buoyant bulk density. When the pile bottom is impermeable, the bulk density of the soil in the water is taken as the saturated bulk density. Third, in areas where there is no overlap, the soil is frozen soil, and the soil side friction, pile end friction, and foundation ratio coefficient are taken from the frozen soil specification values. Fourth, the non-intersecting area has negative frictional resistance, and positive side frictional resistance is not considered; Fifth, the non-intersecting area is expansive soil, and the pile side friction of the expansive soil above the abrupt layer depth is 0; Sixth, when the non-intersecting area is earthquake-liquefiable soil, firstly, calculate the liquefaction reduction factor for each layer of earthquake-liquefiable soil; then, multiply the pile side friction, pile end friction, foundation coefficient, and internal friction angle of the earthquake-liquefiable soil by the liquefaction reduction factor; finally, the allowable bearing capacity of the soil layer above the earthquake-liquefiable soil is not corrected. In the cross regions obtained by step (D), there are various special geological complexes. Considering the geological coupling effect, the calculation parameters and calculation steps after coupling of the cross regions are given. When considering the influence of the cross regions on the soil layer calculation parameters, the neutral point depth is determined first. Soil above the neutral point depth is characterized by negative skin friction; soil below the neutral point depth is characterized by different cases. When the soil below the neutral point depth is also below the upper limit of permafrost depth, the pile side friction, pile end friction, and foundation ratio coefficient of this part of the soil shall be taken from the permafrost specification values. When the soil below the neutral point depth is also above the upper limit of permafrost depth, the calculation parameters for this part of the soil are determined according to the properties of general soil. This part of the soil does not include earthquake-liquefiable soil or expansive soil. When the soil below the neutral point depth is also above the upper limit of permafrost depth, this part of the soil is earthquake liquefaction soil, and the side friction, end friction, subgrade coefficient, and internal friction angle of the soil are all multiplied by the liquefaction reduction factor. When the soil below the neutral point depth is above the upper limit of permafrost depth, and this portion of soil is expansive soil, and this portion of soil is above the abrupt layer depth, the side friction of this portion of soil is not considered.

2. The method for processing railway bridge pile foundation data applicable to any geological conditions according to claim 1, characterized in that: Step (B) divides the action zones of various special geological features according to the seasonal freezing depth line, the upper limit depth line of permafrost, the neutral point depth line, and the abrupt layer depth line. The neutral point depth line is the boundary between negative and positive skin friction, the abrupt layer depth line is the boundary between expansive soil and non-expansive soil, and earthquake-liquefied soil is divided according to soil layers.

Images