A simulation method for mechanical behavior and energy evolution of gas-bearing coal-rock composite structure

Abstract

The present invention discloses a simulation method for the mechanical behavior and energy evolution of a gas-bearing coal-rock combination structure. Numerical simulation is used to study the mechanical behavior and dynamic evolution of energy of different coal-rock combination structures, and the energy proportion of the rock elastic energy in the combination structure is obtained according to the maximum elastic energy of each coal and rock in the combination structure, so as to further clarify the coal-rock energy transfer and the mutual influence mechanism. On this basis, targeted roof and floor treatment measures can be taken according to the different degrees of influence of the roof and floor elastic energy, so as to realize precise prevention and control of mine dynamic disasters under the influence of the roof and floor elastic energy.

Description

Technical Field

[0001] The present invention relates to the field of simulation analysis of coal-rock combined structures, and in particular to a simulation method for mechanical behavior of gas-bearing coal-rock combined structures and their energy evolution. Background Art

[0002] my country is the world's largest coal producer and consumer, and coal occupies an important position in my country's energy structure. Despite the adoption of a series of corresponding prevention and control measures, mine dynamic disasters involving coal-rock gas still occur from time to time. The reason is that the understanding of the mechanism of coal-rock gas disasters is not clear and complete enough. At present, the research on mine dynamic disasters (coal and gas outburst, rock burst) usually focuses on the coal body itself and the role of gas. On the one hand, the relevant research is only based on the analysis of coal seam stress and gas conditions, directly ignoring the elastic energy of the roof and floor. On the other hand, only a rough estimate is given, but in fact there is little specific quantitative research on the elastic energy of the roof and floor, especially under deep mining conditions. Deep mining faces problems such as high ground stress, high temperature, and high gas, which increase the danger of coal and gas outbursts and enhance the impact of coal and rock, further leading to a significant increase in the probability of composite coal-rock dynamic disasters in some high-gas mines and coal and gas outburst mines. This type of disaster not only shows some characteristics of coal and gas outbursts, but also some characteristics of rock bursts. The two dynamic disasters coexist, influence each other, and compound with each other. At the same time, deep composite coal-rock dynamic disasters are complex mechanical processes affected by the dual effects of "high stress (geo-stress) + dynamic disturbance (mining unloading)". The interweaving of multiple factors during the disaster process may lead to mutual inducement, mutual reinforcement, or "resonance" effect during the gestation, occurrence and development of accidents, which makes the occurrence mechanism of composite dynamic disasters more complicated. It is more important to understand the specific role of roof and floor elastic energy in the disaster process. Summary of the invention

[0003] In view of the shortcomings of the prior art, the present invention provides a simulation method for the mechanical behavior and energy evolution of gas-bearing coal-rock combination structures. Numerical simulation is used to analyze the mechanical behavior and dynamic evolution of energy of different coal-rock combination structures, and the energy transfer of coal and rock and its influencing mechanism are analyzed to achieve precise prevention and control of mine dynamic disasters under the influence of rock elastic properties.

[0004] In order to achieve the above object, the present invention adopts the following technical solution:

[0005] A method for simulating the mechanical behavior and energy evolution of a gas-bearing coal-rock composite structure comprises the following steps:

[0006] Step 1: Generate coal rock model by direct generation and indirect generation;

[0007] Step 2: Perform model calculation preprocessing on the model generated in step 1, including applying gas pressure, loading and setting damage judgment conditions;

[0008] Step 3: Carry out model calculations respectively, and compare and analyze the stress distribution, displacement distribution, plastic zone and elastic energy distribution of the coal-rock model generated by direct generation and indirect generation;

[0009] Step 4: quantify the elastic energy of coal and rock and conduct proportion analysis.

[0010] In the step 1, the method for directly generating the coal-rock model is to assign coal body mechanical parameters to a part of the model and assign rock mechanical parameters to the remaining part.

[0011] In the step 1, the method for indirectly generating a coal-rock model includes first generating a coal body model and assigning coal body mechanical parameters, and then generating a rock model and assigning rock mechanical parameters; the coal body model and the rock model are connected by establishing a contact surface, and the contact surface parameters are set to make the coal-rock contact weak contact to varying degrees.

[0012] In the step 2,

[0013] The method of applying gas pressure is as follows: the gas pressure is set according to a pressure gradient, and the gas pressure decreases from the bottom of the coal seam model to the top thereof;

[0014] The loading method is: loading in steps, setting the final loading stress, loading mode is displacement loading or stress loading, and setting the loading step according to the specific research;

[0015] The method for setting the destruction judgment condition is: using displacement mutation or plastic zone destruction area to determine the destruction of the coal-rock composite structure.

[0016] The specific method of step three is:

[0017] Step 3.1: Based on step 2, the stress distribution, displacement distribution and plastic zone distribution of the coal-rock composite structure are output respectively;

[0018] Step 3.2: Use the fish language to write the elastic energy calculation formulas of the coal body and rock in the coal-rock combination structure, and obtain the distribution of the elastic energy of coal and rock and their maximum values ​​through post-processing;

[0019] Step 3.3: Compare and analyze the stress distribution, displacement distribution, plastic zone and elastic energy distribution of the coal-rock models generated directly and indirectly.

[0020] The stress distribution, displacement distribution, plastic zone and elastic energy distribution in step 3.3 are all achieved through the post-processing slice setting, and the slices are all axial slices along the center of the coal-rock composite structure.

[0021] The specific steps of step 4 include:

[0022] Step 4.1: According to the maximum value of the elastic energy of the coal rock obtained in step 3.2, calculate the proportion of the rock elastic energy in the combined structure by dividing the maximum value of the rock elastic energy by the maximum value of the coal elastic energy;

[0023] Step 4.2: Compare and analyze the proportion of rock elastic energy in the combined structure in the coal rock models generated by the two methods.

[0024] The present invention has the following beneficial effects:

[0025] 1) The present invention proposes a simulation method for the mechanical behavior of gas-bearing coal-rock combined structures and their energy evolution based on the actual situation on site, which is a useful supplement to the relevant experimental research on coal-rock gas dynamic disasters;

[0026] 2) The present invention can realize research under various working conditions through specific settings and changes in relevant parameters in the simulation, and has the characteristics of simplicity, speed and efficiency;

[0027] 3) The elastic energy of the coal and rock simulated in the present invention is used to further calculate the energy proportion of the rock elastic energy in the composite structure, which can characterize the specific contribution of the rock elastic energy and fully consider the influence of the rock elastic energy. It has important theoretical significance and practical engineering value, and is of positive significance for the prediction and prevention of composite dynamic disasters in mines such as rock burst-coal and gas outbursts induced by deep mining. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a flow chart of a method for simulating mechanical behavior of gas-bearing coal-rock combination structure and its energy evolution according to the present invention. DETAILED DESCRIPTION

[0029] In order to fully reflect the characteristics and advantages of the present invention, it will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] like Figure 1 As shown, a method for simulating the mechanical behavior of gas-bearing coal-rock combination structure and its energy evolution includes the following steps:

[0031] The first step is modeling, which can be divided into the following two methods:

[0032] Method 1: directly generate the model, in which part of the model is assigned coal mechanical parameters, and the remaining part is assigned rock mechanical parameters;

[0033] Method 2: Generate a coal model and assign coal mechanical parameters, then generate a rock model and assign rock mechanical parameters; the coal-rock model is connected by establishing a contact surface, wherein the contact surface parameters are set to make the coal-rock contact weak to different degrees;

[0034] The second step is model operation preprocessing, which is specifically divided into the following three steps:

[0035] Step 2.1: applying gas pressure to the model generated in the first step, wherein the gas pressure is set according to a pressure gradient, wherein the gas pressure decreases from the bottom of the coal seam model to the top thereof;

[0036] Step 2.2: Load the model generated in the first step in steps, set the final loading stress, use displacement loading or stress loading, and set the loading step according to the research;

[0037] Step 2.3: Set the damage judgment conditions and use the displacement mutation or plastic zone damage area to determine the damage of the coal-rock combination structure;

[0038] The third step is to analyze the simulation results, which is specifically divided into the following three steps:

[0039] Step 3.1: Output the stress distribution, displacement distribution and plastic zone distribution of the coal-rock composite structure in sequence according to the simulation results of method 1 and method 2 in the first step respectively;

[0040] Step 3.2: Use fish language to write the elastic energy calculation formulas of coal body and rock in the coal-rock combination structure, and obtain the distribution of elastic energy of coal and rock and their maximum values ​​through post-processing;

[0041] Step 3.3: Compare and analyze the stress distribution, displacement distribution, plastic zone and elastic energy distribution of coal and rock in the combined structure of method 1 and method 2;

[0042] The fourth step is to quantify the elastic energy of coal and rock and analyze its proportion, which is specifically divided into the following two steps:

[0043] Step 4.1: Based on the maximum value of the elastic energy of the coal and rock obtained in step 3.2, calculate the proportion of the rock elastic energy in the combined structure by dividing the maximum value of the rock elastic energy by the maximum value of the coal elastic energy;

[0044] Step 4.2: Compare and analyze the proportion of rock elastic energy in the combined structure in Method 1 and Method 2.

[0045] The stress distribution, displacement distribution, plastic zone and elastic energy distribution in step 3.3 are all achieved through the slice setting of post-processing, and the slices are all axial slices along the center of the coal-rock composite structure.

[0046] Although the above describes the specific implementation mode of the present invention in conjunction with the accompanying drawings, it is not intended to limit the scope of protection of the present invention. Those skilled in the art should understand that various modifications or variations that can be made by those skilled in the art on the basis of the technical solution of the present invention without creative work are still within the scope of protection of the present invention.

Claims

1. A method for simulating the mechanical behavior and energy evolution of gas-bearing coal-rock composite structures, characterized in that: The following steps are involved: Step 1: Generate coal rock model by direct generation and indirect generation; The method of directly generating the coal-rock model is to assign the mechanical parameters of the coal mass to one part of the model and the mechanical parameters of the rock to the remaining part; The method of indirectly generating a coal-rock model includes first generating a coal model and assigning coal mechanical parameters, then generating a rock model and assigning rock mechanical parameters; the coal model and the rock model are connected by establishing a contact surface, and the contact between the coal and the rock is made into weak contact of different degrees by setting the contact surface parameters; Step 2: Perform model calculation preprocessing on the models generated in step 1, including applying gas pressure, loading and setting damage judgment conditions; The method of applying gas pressure is as follows: the gas pressure is set according to a pressure gradient, and the gas pressure decreases from the bottom of the coal seam model to the top thereof; The loading method is: loading in steps, setting the final loading stress, loading mode is displacement loading or stress loading, and setting the loading step according to the specific research; The method of setting the damage judgment condition is: using displacement mutation or plastic zone damage area to judge the damage of coal-rock combination structure; Step 3: Carry out model calculations respectively, and compare and analyze the stress distribution, displacement distribution, plastic zone and elastic energy distribution of the coal-rock model generated by the direct generation method and the indirect generation method; The specific method is: Step 3.1: Based on step 2, the stress distribution, displacement distribution and plastic zone distribution of the coal-rock composite structure are output respectively; Step 3.2: Use the fish language to write the elastic energy calculation formulas of the coal body and rock in the coal-rock combination structure, and obtain the distribution of the elastic energy of coal and rock and their maximum values ​​through post-processing; Step 3.3: Compare and analyze the stress distribution, displacement distribution, plastic zone and elastic energy distribution of the coal-rock models generated by direct generation and indirect generation; Step 4: quantify the elastic energy of coal and rock and analyze its proportion; The specific steps include: Step 4.1: According to the maximum value of the elastic energy of the coal rock obtained in step 3.2, calculate the proportion of the rock elastic energy in the combined structure by dividing the maximum value of the rock elastic energy by the maximum value of the coal elastic energy; Step 4.2: Compare and analyze the proportion of rock elastic energy in the combined structure in the coal rock models generated by the two methods.

2. A method for simulating the mechanical behavior and energy evolution of a gas-bearing coal-rock composite structure according to claim 1, characterized in that: The stress distribution, displacement distribution, plastic zone and elastic energy distribution in step 3.3 are all achieved through the post-processing slice setting, and the slices are all axial slices along the center of the coal-rock composite structure.

Images