CN-115221767-B - Method for measuring rock water diffusion coefficient and simulating water absorption process and related equipment

CN115221767BCN 115221767 BCN115221767 BCN 115221767BCN-115221767-B

Abstract

The application provides a method and related equipment for rock moisture diffusion coefficient measurement and water absorption process simulation, which are used for representing the water absorption state of each particle on a microscale level through a microscale saturation coefficient on the basis of a particle discrete element technology, and realize numerical value refined modeling, so that the rock water absorption process can be accurately and efficiently reduced, and the practical value is remarkably improved.

Inventors

BIAN KANG
CHEN YANAN
LIU JIAN
LIU ZHENPING
AI FEI

Assignees

中国科学院武汉岩土力学研究所
中国科学院武汉岩土力学研究所

Dates

Publication Date: 20260421
Application Date: 20220621
Priority Date: 20220621

Claims (7)

1. A method for rock moisture diffusion coefficient determination and water absorption process simulation, the method comprising: after a target rock sample is determined, acquiring sample water saturation coefficients of the target rock sample under different water absorption time through a rock water absorption test; Constructing a particle initial framework of a discrete element standard rock sample model, and fully balancing internal stress of the discrete element standard rock sample model; a discrete element program based on mass conservation and water diffusion equation is compiled, and a relation between macroscopic and microscopic parameter indexes in the discrete element standard rock sample model is established so as to simulate a natural diffusion rule of water in rock, wherein the relation between the macroscopic and microscopic parameter indexes comprises a relation between a water diffusion coefficient and a water saturation coefficient; Establishing water absorption boundary conditions and initial conditions in the discrete element standard rock sample model, changing macroscopic water diffusion coefficients, simulating a water absorption process, and obtaining macroscopic water saturation coefficient-time curves under different macroscopic water diffusion coefficients until the curves are identical with the sample water saturation coefficients; Based on the discrete element standard rock sample model with the calibration parameters, carrying out discrete element simulation of the rock under various working conditions and under different water absorption states; The method for obtaining the sample water saturation coefficient of the target rock sample under different water absorption time through the rock water absorption test comprises the following steps: In the rock water absorption test, after the mass of the target rock sample is unchanged after free water absorption, calculating the sample water saturation number of the target rock sample under different water absorption time by the following formula: , , , Wherein W is rock water absorption, m 1 is the mass of immersed rock under different water absorption time, m is the mass of dry rock sample, W s is rock saturated water absorption, m 2 is the saturated mass of immersed rock sample, and W is rock saturation coefficient; the mesoscopic water diffusion formula programmed into the discrete element program is: , Wherein t is time, w i * is the mesoscopic water saturation coefficient of particle i, N is the number of all particles adjacent to the particle i, d ij is the mesoscopic water diffusion coefficient of the particle i and particle j, aw ij * is the difference between the mesoscopic water saturation coefficients of the particle i and the particle j, and L ij is the center distance of the particle i and the particle j; the conversion relationship of the macroscopic moisture diffusion coefficient and the microscopic moisture diffusion coefficient programmed into the discrete element program is: , , Wherein D ic is the mesoscopic moisture diffusion coefficient of the particle i on contact c, D is the macroscopic moisture diffusion coefficient tensor of the particle i in its equivalent watershed volume, V i is the equivalent continuous watershed volume of the particle i, l ic is the distance from the center of the particle i to the contact boundary, D ij is the mesoscopic moisture diffusion coefficients of the particle i and the particle j, and D jc is the mesoscopic moisture diffusion coefficient of the particle i on the contact c.
2. The method according to claim 1, wherein the method further comprises: Processing rock into a standard sample with phi of 50mm multiplied by 100mm, putting the standard sample into a baking oven with the temperature of 105-110 ℃ to bake for 12 hours, taking out, putting into a dryer to cool to room temperature, and weighing the mass; during the rock water absorption test, water is firstly injected to the 1/4 height of the standard sample, then water is respectively injected to the 1/2 and 3/4 height of the standard sample every 2 hours, water is added to the height of 20mm above the top surface of the standard sample after 6 hours, and the standard sample is immersed by water and then absorbs water freely.
3. The method according to claim 1, wherein for the simulation of the water absorption process, the macrosaturation coefficient of the model required for the macrosaturation coefficient-time curve obtained is obtained by: , Wherein w is the macroscopic water saturation coefficient, w is * is the microscopic water saturation coefficient of the particle i in a saturated state, and w is * is 1.0.
4. The method according to claim 1, wherein the content of the discrete element simulation specifically comprises: Numerical simulation research of the water absorption process of a standard cylinder and other different forms of rocks Dan Shiyang; measuring the water diffusion coefficient of a standard cylinder and other different forms of rocks; and combining deterioration rules of macro-micro parameters of the geotechnical mechanics under different water saturation coefficients.
5. A device for rock moisture diffusion coefficient determination and water absorption process simulation, the device comprising: The acquisition unit is used for acquiring sample water saturation coefficients of the target rock sample under different water absorption time through a rock water absorption test after the target rock sample is determined; the construction unit is used for constructing a particle initial framework of the discrete element standard rock sample model and fully balancing the internal stress of the discrete element standard rock sample model; the preparation unit is used for preparing a discrete element program based on mass conservation and water diffusion equation, and establishing a relation between macroscopic and microscopic parameter indexes in the discrete element standard rock sample model so as to simulate a natural diffusion rule of water in the rock, wherein the relation between the macroscopic and microscopic parameter indexes comprises a relation between a water diffusion coefficient and a water saturation coefficient; the simulation unit is used for establishing water absorption boundary conditions and initial conditions in the discrete element standard rock sample model, changing macroscopic water diffusion coefficients, simulating a water absorption process and obtaining macroscopic water saturation coefficient-time curves under different macroscopic water diffusion coefficients until the curves are consistent with the sample water saturation coefficients; The development unit is used for developing discrete element simulation of the rock under various working conditions and under different water absorption states based on the discrete element standard rock sample model with the calibration parameters; The apparatus being for performing the method of any one of claims 1 to 4.
6. A processing device comprising a processor and a memory, the memory having stored therein a computer program, the processor executing the method of any of claims 1 to 4 when invoking the computer program in the memory.
7. A computer readable storage medium storing a plurality of instructions adapted to be loaded by a processor to perform the method of any one of claims 1 to 4.

Description

Method for measuring rock water diffusion coefficient and simulating water absorption process and related equipment Technical Field The application relates to the field of rock seepage process analysis, in particular to a method for measuring a rock water diffusion coefficient and simulating a water absorption process and related equipment. Background As a porous medium material, rock has physical and mechanical properties of water absorption, natural diffusion can occur after moisture permeates into pore channels from the surface of the rock, the rock contacts with the inside of the rock, and complex physical, mechanical and chemical actions and the like are generated, so that the rock structure is damaged. In geotechnical engineering practice, rocks are often corroded by water such as rainwater, rivers, underground water, water vapor and the like, the strength and rigidity of the rocks are weakened due to the existence of the water, and many engineering geological disasters such as tunnel water burst, tunnel collapse, mining area ground surface collapse and the like are caused, wherein the action range of the water in a rock stratum plays a decisive role in predicting the engineering geological disasters, and therefore, the quantitative characterization of the distribution, the diffusion range and the uniformity of the water in the rock stratum is studied to have great engineering significance. In the field, a certain technical difficulty exists in acquiring the diffusion characteristics of water in the rock stratum, so that the research is often carried out by adopting an indoor test and numerical simulation means. The common indoor test means is to calculate the macroscopic water content by measuring the weight of the dry rock sample and the water-containing rock sample, but the diffusion state of water in the rock cannot be described, so that the water content in the rock cannot be accurately measured. In the numerical simulation means, finite element software is often used for coupling a humidity field to simulate the water diffusion state in the rock, but the rock is difficult to consider as a crack in a discontinuous medium material and anisotropy on a mesoscopic level, and in this case, discrete particles can consider structural randomness in the mesoscopic category to reflect the water diffusion rule in the rock more truly. However, in the research process of the prior related technology, the inventor finds that the current method for representing the water diffusion in the rock based on the discrete elements of the particles is mostly realized by the action of coupling fluid force, but mainly has 3 problems that (1) the diffusion characteristics of the water in the rock cannot be quantified, the water absorption process of the rock cannot be represented, the real-time water content and the water diffusion coefficient of the rock cannot be measured, (2) the simulation range has limitations, the represented state is the seepage process of the saturated rock and the water absorption process of the rock gradually saturated from drying cannot be reflected, and (3) the calculation speed is slow due to the dependence on a fluid grid, the method is not suitable for simulation of large-scale engineering, and the practical value is obviously limited. Disclosure of Invention The application provides a method and related equipment for rock moisture diffusion coefficient measurement and water absorption process simulation, which are used for representing the water absorption state of each particle on a mesoscopic level through a mesoscopic saturation coefficient on the basis of a particle discrete element technology, and realize numerical refinement modeling, so that the rock water absorption process can be accurately and efficiently reduced, and the practical value is remarkably improved. In a first aspect, the application provides a method for rock moisture diffusion coefficient determination and water absorption process simulation, the method comprising: After determining a target rock sample, acquiring sample water saturation coefficients of the target rock sample under different water absorption times through a rock water absorption test; constructing a particle initial framework of the discrete element standard rock sample model, and fully balancing the internal stress of the discrete element standard rock sample model; a discrete element program based on mass conservation and a water diffusion equation is compiled, and a relation between macroscopic and microscopic parameter indexes in a discrete element standard rock sample model is established so as to simulate a natural diffusion rule of water in rock, wherein the relation between the macroscopic and microscopic parameter indexes comprises a relation between a water diffusion coefficient and a water saturation coefficient; Establishing water absorption boundary conditions and initial conditions in a discrete element standard rock sample model, chang