CN-121980889-A - Wet ballast bed modeling method considering liquid bridge force

CN121980889ACN 121980889 ACN121980889 ACN 121980889ACN-121980889-A

Abstract

The invention discloses a wet ballast bed modeling method considering liquid bridge force, and belongs to the technical field of railway particle flow number simulation. The method comprises the steps of constructing a discrete element model of the ballast particles to obtain a clamp polymer, constructing a liquid bridge force calculation model, constructing a liquid bridge contact constitutive model according to the liquid bridge force calculation model, and constructing a discrete element model of a wet ballast bed according to the discrete element model of the ballast particles and the liquid bridge contact constitutive model. According to the invention, by considering the adhesion and aggregation effect of the liquid bridge force on the wetting ballast bed, the method is used for testing the repose angle under the wetting condition on one hand, and constructing the liquid bridge contact constitutive model according to the liquid bridge force calculation model on the other hand, so that the mechanical property of the simulation wetting ballast bed is more accurate, and the method has a certain significance in researching the wetting ballast.

Inventors

WANG XUEJUN
CAO FAN

Assignees

昆明理工大学

Dates

Publication Date: 20260505
Application Date: 20260120

Claims (9)

1. A method of modeling a wet ballast bed in consideration of a liquid bridge force, comprising: S1, constructing a discrete element model of ballast particles to obtain a ring polymer; S2, constructing a liquid bridge force calculation model; s3, constructing a liquid bridge contact constitutive model according to the liquid bridge force calculation model; s4, constructing a wet ballast bed discrete element model according to the ballast particle discrete element model and the liquid bridge contact constitutive model.
2. The wet ballast bed modeling method considering the liquid bridge force according to claim 1, wherein S1 is specifically: And placing the ballast particles with different shapes on a scanning table at different angles, respectively scanning by utilizing laser to obtain the outer contours of the ballast particles with different shapes, and filling the extracted outer contours by adopting a ball unit to obtain the ring polymer.
3. The wet ballast bed modeling method considering the liquid bridge force according to claim 1, wherein S2 comprises: s201, taking the outer surface of a liquid bridge between any two adjacent wet ballast particles as a cylinder shape of the side surface of a round table, and constructing a liquid bridge volume expression; S202, defining the existence condition of the liquid bridge force, namely when the distance between two adjacent wet ballast particles is smaller than or equal to a critical fracture distance, the liquid bridge exists, otherwise, the liquid bridge breaks, and the liquid bridge force disappears; S203, constructing a liquid bridge force calculation model according to the existence conditions of the liquid bridge volume and the liquid bridge force, wherein the liquid bridge force calculation model expression is as follows: ; Wherein, the Indicating the force of the liquid bridge, As a function of the surface tension coefficient, For the solid-liquid contact angle, Is the distance between two wet ballast particles, In order to be of equivalent particle radius, Is the liquid bridge volume.
4. A wet ballast bed modeling method considering liquid bridge forces according to claim 3, wherein said liquid bridge volumetric expression: ; Wherein, the Is a half-filled corner which is to be filled, And The radiuses of two adjacent wet railway ballast particles are respectively.
5. A wet ballast bed modeling method considering liquid bridge force as claimed in claim 3, wherein said critical breaking distance is as follows The expression is: 。
6. The wet ballast bed modeling method considering liquid bridge force according to claim 1, wherein the liquid bridge contact constitutive model expression is: ; Wherein, the In order for the total contact force to be the same, For the equivalent modulus of elasticity, the elastic modulus, As a normal direction of the overlap vector, In order to be of equivalent particle radius, Is the liquid bridge force.
7. The method for modeling the wet ballast bed taking the liquid bridge force into consideration as the claim 1, wherein the method is characterized in that the wet ballast bed discrete element model is constructed by firstly establishing a ballast bed outline model, arranging sleepers at corresponding positions, setting model parameters, carrying out discrete element filling on the ballast bed by combining a jump polymer established in the step S1 and the liquid bridge contact constitutive model, and obtaining the wet ballast bed discrete element model through gravity deposition and compaction to reach an initial stable state after filling.
8. The method for modeling the wet ballast bed taking the liquid bridge force into consideration is characterized by comprising the steps of setting model parameters, carrying out a ballast particle repose angle test under a humidifying condition according to a liquid bridge contact constitutive model, setting a cylindrical wall surface, setting a ballast particle parameter, a liquid parameter and a particle-cylinder contact parameter, setting a contact model between a ballast and a ballast as the liquid bridge contact constitutive model, generating ballast particles in a cylinder, filling the ballast particles in the cylinder by adopting a rain fall method, naturally settling the particles in a container under the action of gravity after filling is finished until the ballast particles reach stability, slowly lifting an upper cylindrical wall according to a preset speed after the ballast particles are completely stabilized, and naturally sliding the ballast particles in the cylinder down to be in a stacked state under the action of gravity, wherein under the humidifying condition, the surface tension coefficient in the ballast particle parameters takes a value range of 0.065-0.072N/m.
9. The wet ballast bed modeling method considering the liquid bridge force according to claim 7 or 8, wherein the model parameters comprise ballast particle parameters and liquid parameters, wherein the ballast particle parameters comprise ballast particle materials, densities, shear moduli, poisson ratios and friction coefficients, and the liquid parameters comprise surface tension coefficients and solid-liquid contact angles at which two wet ballast particles are contacted.

Description

Wet ballast bed modeling method considering liquid bridge force Technical Field The invention relates to a wet ballast bed modeling method considering liquid bridge force, and belongs to the technical field of railway particle flow number simulation. Background The railway is a backbone of a comprehensive transportation system, the status and the effect in the economic and social development are important, and the railway ballast layer is used as an important component of a railway track structure and mainly plays roles of bearing load, draining water, damping and the like, and the mechanical property of the railway ballast layer directly influences the smoothness, stability and train operation safety of the track. Traditionally, research on mechanical behavior of railway ballast is based on the assumption of dry conditions. However, railways are inevitably subjected to various humidity environments in actual operation, such as rainy days, high humidity areas or ponding environments caused by unsmooth drainage. The presence of moisture can significantly alter the interaction forces between the ballast particles, thereby affecting the macroscopic mechanical response of the entire ballast layer, such as strength, deformation, and stability. Discrete element Method (DISCRETE ELEMENT Method, DEM) has become a powerful tool for researching the mechanical behavior of ballast particles because of the capability of accurately simulating the non-continuity and large deformation characteristics of the particle materials. Currently, DEM simulation techniques for dry beds are relatively well established, and the Hertz-Mindlin contact model is typically used to simulate interparticle elastic contact and friction. The existing wet ballast discrete element model has an important limitation that the influence of a humidity environment is not fully considered generally or the depiction of the liquid bridge force is too simplified. Specifically, the current model is mostly based on the JKR contact theory to simulate the contact behavior of the wet ballast, but the method is difficult to truly reflect the contact mechanical properties of the wet ballast under different water contents. In fact, the mechanical properties of wet railway ballasts have a significant dependence on the water content, whereas existing models have insufficient characterizations in this critical aspect. Therefore, establishing a mechanism that more comprehensively and accurately simulates the mechanical properties of a wet ballast bed is a problem to be solved. Disclosure of Invention The invention provides a wet ballast modeling method considering liquid bridge force, which is used for testing an repose angle under a wet condition by considering the cohesive action of the liquid bridge force on the wet ballast, and constructing a liquid bridge contact constitutive model according to a liquid bridge force calculation model so that the mechanical property of the wet ballast is simulated more accurately, and has a certain significance in researching wet ballast. The technical scheme of the invention is as follows: a wet ballast bed modeling method taking into account liquid bridge forces, comprising: S1, constructing a discrete element model of ballast particles to obtain a ring polymer; S2, constructing a liquid bridge force calculation model; s3, constructing a liquid bridge contact constitutive model according to the liquid bridge force calculation model; s4, constructing a wet ballast bed discrete element model according to the ballast particle discrete element model and the liquid bridge contact constitutive model. Further, the S1 specifically is: And placing the ballast particles with different shapes on a scanning table at different angles, respectively scanning by utilizing laser to obtain the outer contours of the ballast particles with different shapes, and filling the extracted outer contours by adopting a ball unit to obtain the ring polymer. Further, the step S2 includes: s201, taking the outer surface of a liquid bridge between any two adjacent wet ballast particles as a cylinder shape of the side surface of a round table, and constructing a liquid bridge volume expression; S202, defining the existence condition of the liquid bridge force, namely when the distance between two adjacent wet ballast particles is smaller than or equal to the critical fracture distance When the liquid bridge exists, otherwise, the liquid bridge breaks, and the liquid bridge force disappears; S203, constructing a liquid bridge force calculation model according to the existence conditions of the liquid bridge volume and the liquid bridge force, wherein the liquid bridge force calculation model expression is as follows: ; Wherein, the Indicating the force of the liquid bridge,As a function of the surface tension coefficient,For the solid-liquid contact angle,Is the distance between two wet ballast particles,In order to be of equivalent particle radius,Is the liqui