CN-122020817-A - Tunnel roof damage time prediction method and system

CN122020817ACN 122020817 ACN122020817 ACN 122020817ACN-122020817-A

Abstract

The invention discloses a method and a system for predicting the failure time of a roadway roof, belonging to the technical field of mine rock mass mechanics and safety engineering; the method comprises the steps of identifying a roof stratum structure and each layered lithology through drilling peeping, drilling a representative rock sample, measuring the cracking strength and the peak strength of the rock sample through a uniaxial compression test, selecting a plurality of stress levels between the roof stratum structure and each layered lithology, performing a creep test, synchronously monitoring axial strain and acoustic emission signals, determining an acceleration creep starting moment according to mutation characteristics of the acceleration creep starting moment as the breaking time under the stress, establishing a stress-breaking time relation model of each lithology, and finally selecting a corresponding model according to the actual stratum structure and the ground stress state of a roadway to predict the breaking time of the rock at different layers of the roof.

Inventors

WU XIANGYE
YAN YUHANG
CHENG XIAOLONG
Yuan Shengta
ZHOU GUANGDONG
MIAO CHENGYU

Assignees

内蒙古科技大学

Dates

Publication Date: 20260512
Application Date: 20260413

Claims (5)

1. A method for predicting failure time of a roadway roof, the method comprising: Drilling and peeping the tunnel roof, and identifying the rock stratum layered structure and each layered lithology of the tunnel roof; carrying out a uniaxial compression test on each lithology core sample to determine the cracking strength and the peak strength of each lithology core sample; In the whole process of the creep loading test, the axial strain and acoustic emission signals of each lithology core sample are synchronously monitored, and the starting moment of each lithology core sample entering an accelerating creep rupture stage is judged according to the characteristics of the sudden change of the axial strain rate and the rapid increase of the acoustic emission signal event rate, and the moment is recorded as the creep rupture time under the corresponding stress level; According to creep rupture time obtained under different stress levels, a stress-rupture time relation model of each lithology core sample is established; And selecting a stress-damage time relation model of the corresponding lithology core sample according to the actual layered lithology structure of the tunnel roof and the actual stressed state of each rock stratum obtained through ground stress measurement or numerical simulation, and predicting the damage time of the rock at different layers of the tunnel roof.
2. The method for predicting the failure time of a roadway roof according to claim 1, further comprising, after predicting the failure time of the rock at different levels of the roadway roof, giving a priority to the rock layer which is liable to be broken first based on the cracking strength and the peak strength of each rock layer of the roadway roof or on the preliminary prediction result obtained based on the stress-failure time relation model.
3. The method for predicting the failure time of the roadway roof according to claim 2, wherein the priority warning comprises the steps of dividing warning grades: Dividing the roadway roof damage risk into multiple early warning levels based on the difference between the predicted damage time and the current time and by combining the rock deformation and the acoustic emission activity state of the roadway roof on-site monitoring, wherein the early warning levels comprise a first early warning corresponding to the difference being larger than a first set time threshold, a second early warning corresponding to the difference being smaller than or equal to the first set time threshold and larger than a second set time threshold, and a third early warning corresponding to the difference being smaller than or equal to the second set time threshold.
4. The method for predicting the failure time of the roadway roof according to claim 3, further comprising the step of performing an early warning response after dividing the early warning level, wherein the method comprises the following steps: When the early warning level reaches a preset level, outputting corresponding early warning information, and guiding the site to execute corresponding safety response measures according to the early warning information, wherein the safety response measures comprise at least one of reinforcing or adjusting roadway support, limiting personnel to enter a dangerous area, and carrying out key monitoring or temporary reinforcement on a roadway top plate.
5. A roof failure time prediction system, the system comprising: the on-site investigation and sampling module is used for carrying out drilling peeping on the roadway top plate and identifying the rock stratum layered structure and each layered lithology of the roadway top plate; The rock mechanical parameter measurement module is used for carrying out a uniaxial compression test on each lithology core sample and determining the cracking strength and the peak strength of each lithology core sample; The creep rupture test module is used for selecting a plurality of different stress levels between the cracking strength and the peak strength, and respectively carrying out a creep loading test on each lithologic core sample under constant axial stress; in the whole creep loading test process, synchronously monitoring axial strain and acoustic emission signals of each lithology core sample, judging the starting moment of each lithology core sample entering an accelerating creep rupture stage according to the characteristic of sudden change of the axial strain rate and rapid increase of the acoustic emission signal event rate, and recording the moment as creep rupture time under the corresponding stress level; The relation model construction module is used for building a stress-damage time relation model of each lithology core sample according to creep damage time obtained under different stress levels; The roof breaking time prediction module is used for selecting a stress-breaking time relation model corresponding to the lithology core sample according to the actual layered lithology structure of the tunnel roof and the actual stress state of each rock stratum obtained through ground stress measurement or numerical simulation, and predicting the breaking time of the rock at different layers of the tunnel roof.

Description

Tunnel roof damage time prediction method and system Technical Field The invention relates to the technical field of mine rock mass mechanics and safety engineering, in particular to a method and a system for predicting the failure time of a roadway roof. Background The tunnel roof failure time prediction is a core subject in the field of mine and tunnel engineering safety, and aims to pre-judge the specific time of instability of roof strata under the action of load, so that a key basis is provided for taking active prevention and control measures. The accurate time prediction is realized, and the method has important significance for avoiding casualties, reducing property loss and guaranteeing continuous production of engineering. At present, the evaluation of the stability of the tunnel roof in engineering practice mainly depends on the calculation of stability coefficients based on the rock uniaxial or triaxial instantaneous compressive strength or the qualitative analog judgment by referring to engineering experience similar to geological conditions. Such methods consider rock mass as an elastoplastic material that is instantaneously broken, and stability is judged by analyzing whether its stress state reaches a strength limit. However, failure of roadway roof rock mass under long term ground and mining stresses is often a time dependent progressive creep process. The conventional method focusing on instantaneous strength or experience judgment cannot describe the creep (i.e. slow deformation growth with time) mechanical behavior of the rock under constant stress, so that the evolution rule of the top plate from initial damage, crack stability expansion to final acceleration instability is difficult to reveal. The prior art can not give quantitative and prospective prediction on the key problem of damage occurrence, so that the support design is often biased to be passive, disaster early warning is also seriously delayed, and urgent requirements of modern mines on safe and accurate prevention and control can not be met. Disclosure of Invention The invention aims to provide a roadway roof damage time prediction method, which realizes accurate and reliable time prediction of a progressive damage process of a roadway roof. In order to solve the technical problems, the embodiment of the invention provides a roadway roof damage time prediction method, which comprises the following steps: Drilling and peeping the tunnel roof, and identifying the rock stratum layered structure and each layered lithology of the tunnel roof; carrying out a uniaxial compression test on each lithology core sample to determine the cracking strength and the peak strength of each lithology core sample; In the whole process of the creep loading test, the axial strain and acoustic emission signals of each lithology core sample are synchronously monitored, and the starting moment of each lithology core sample entering an accelerating creep rupture stage is judged according to the characteristics of the sudden change of the axial strain rate and the rapid increase of the acoustic emission signal event rate, and the moment is recorded as the creep rupture time under the corresponding stress level; According to creep rupture time obtained under different stress levels, a stress-rupture time relation model of each lithology core sample is established; And selecting a stress-damage time relation model of the corresponding lithology core sample according to the actual layered lithology structure of the tunnel roof and the actual stressed state of each rock stratum obtained through ground stress measurement or numerical simulation, and predicting the damage time of the rock at different layers of the tunnel roof. In some optional embodiments, the method further comprises the step of performing priority early warning on the rock stratum which is easy to break first based on the cracking strength and the peak strength of each rock stratum of the roadway roof or based on a preliminary prediction result obtained by a stress-breaking time relation model after predicting the breaking time of the rock at different layers of the roadway roof. In some optional embodiments, the priority early warning includes dividing early warning grades, and the specific steps are as follows: Dividing the roadway roof damage risk into multiple early warning levels based on the difference between the predicted damage time and the current time and by combining the rock deformation and the acoustic emission activity state of the roadway roof on-site monitoring, wherein the early warning levels comprise a first early warning corresponding to the difference being larger than a first set time threshold, a second early warning corresponding to the difference being smaller than or equal to the first set time threshold and larger than a second set time threshold, and a third early warning corresponding to the difference being smaller than or equal to the second set time thres