CN-121637644-B - Dynamic prediction method and system for sudden-by-accident risk of high-pressure air bags close to tunnel

CN121637644BCN 121637644 BCN121637644 BCN 121637644BCN-121637644-B

Abstract

The invention provides a dynamic prediction method and a dynamic prediction system for a sudden burst risk of a high-pressure air sac close to a tunnel, which comprise the steps of (1) obtaining air sac parameters (pressure, equivalent radius), rock mass parameters (strength parameters, attenuation coefficients) and engineering parameters (rock wall thickness and supporting strength) through geological radar, drilling pressure measurement, indoor triaxial test and the like, (2) calculating equivalent plastic strain based on tunnel convergence displacement, updating surrounding rock strength by combining an attenuation model, calculating rock wall anti-damage capacity and air sac damage force to obtain a sudden burst risk index R, (3) dividing low (R is more than or equal to 1.5), medium (R is more than or equal to 1.0 and less than or equal to 1.5), high (R is more than or equal to 0.5 and less than or equal to 1.0) and extremely high (R is more than or equal to 0.5) risk grades, and outputting early warning and disposal measures. The method solves the problem of blank prediction of the non-coal-series stratum air bags, realizes dynamic quantitative prediction, improves construction safety, shortens construction period, and is suitable for deep tunnels and large-burial-depth underground projects.

Inventors

GUO YONGFA
TIAN SIMING
GONG JIANGFENG
YUAN YUNHONG
QUAN FEI
ZHANG LIN
YAO HEDONG
YANG JINJING
DING WENYUN
LI CHUANLIN
LI GUIMIN
YANG CHANGYU
YIN HONGBO
Shu Hongyi
SU PEIDONG
ZHAO YU
LIU SONGLIANG

Assignees

中铁二院昆明勘察设计研究院有限责任公司

Dates

Publication Date: 20260505
Application Date: 20260204

Claims (7)

1. The dynamic prediction method for the sudden-by-burst risk of the high-pressure air bags close to the tunnel is characterized by comprising the following steps of: Step1, parameter acquisition, namely acquiring air bag parameters, rock mass parameters and engineering parameters; The parameters of the air bag comprise the pressure P g and the equivalent radius R g of the air in the air bag; The rock mass parameters comprise initial strength parameters of the rock mass, residual strength parameters, elastic modulus E, poisson's ratio v and attenuation coefficients, wherein the initial strength parameters of the rock mass comprise cohesive force c 0 and an internal friction angle phi 0 , the residual strength parameters comprise cohesive force c r and an internal friction angle phi r , and the attenuation coefficients comprise alpha and beta; The engineering parameters comprise the initial thickness D 0 of a rock wall between a tunnel and an air bag, the equivalent radius R tun of a tunnel excavation section, the time t after the tunnel excavation, the supporting strength sigma sup and the ground stress, wherein the ground stress comprises the vertical ground stress sigma v and the horizontal ground stress sigma h ; Step2, real-time analysis phase: Step201 calculation of the stability of the rock wall based on the on-site monitored tunnel convergence displacement u by empirical relationship Calculation of equivalent plastic strain of the rock wall between tunnel and balloon =kxu/R tun The k is an empirical coefficient; step202 dynamic update of surrounding rock strength equivalent plastic strain calculated according to Step201 The current cohesive force c (t) and the internal friction angle phi (t) of the rock wall are updated in real time by combining a rock mass intensity attenuation model, wherein the attenuation model is as follows: c(t)=c 0 -(c 0 -c r )×(1-e^(-α )), φ(t)=φ 0 -(φ 0 -φ r )×(1-e^(-β )); Step203 calculation of the wall resistance to failure based on the mole-coulomb criterion, calculating the wall resistance to failure R s by the formula R s =K 1 ×c(t)×D t ×K 2 +K 2 ×σ n ×D t ×tan phi (t), wherein D t is the current wall thickness, D t =D 0 - X D 0 , wherein K 1 、K 2 is a geometric coefficient related to the shape of a potential slip crack surface, K 1 =1.0、K 2 =0.8 when the slip crack surface is a plane, K 1 =1.2、K 2 =1.0 when the slip crack surface is an arc surface, sigma n is an average normal stress on the slip crack surface, sigma n =σ h ×cos²θ+σ v ×sin²θ+σ sup and theta is a horizontal included angle between the tunnel excavation contour line and the nearest position of the high-pressure air bag edge line; Step204, calculating the high-pressure air bag destructive power, namely calculating the high-pressure air bag destructive power F gas according to a formula F gas =P g ×H g multiplied by b, wherein H g is the effective projection height of the high-pressure air bag on the side close to the tunnel and is obtained through three-dimensional modeling measurement, and b is the unit height of the air bag at the most unfavorable section in the thrust direction, and 1m is taken; Step205. Calculating the risk of sudden changes by calculating the risk of sudden changes R by the formula r=r s /F gas ; Step3, risk early warning and outcome evaluation, namely dividing risk grades according to the sudden-fire risk index R, and correspondingly outputting early warning information and disposal measures.
2. The method of claim 1, wherein in Step1, P g is detected and obtained through advanced drilling and a portable gas pressure recorder, R g is detected and obtained through geological radar and a drilling imager, D 0 is detected and obtained through geological radar profile, sigma v =γh, gamma is the weight of a rock mass, h is the buried depth of a tunnel, sigma h =Kσ v and K are side pressure coefficients, values are 0.6-0.9, triaxial compression tests are conducted through a rock mechanical testing machine, confining pressure is 0.5-1.5 MPa, initial strength parameters c 0 、φ 0 of the rock mass are obtained, residual strength parameters c r 、φ r are determined through post-peak softening section tests, based on a full-range stress-strain curve, nonlinear least square inversion analysis is adopted, calibrated attenuation coefficients alpha, beta and alpha are 0.8-1.2, beta is 0.05-0.15, the measurement accuracy of the portable gas pressure recorder is not lower than +/-0.01 MPa, the geological radar detection depth is not lower than 30m, and the stress of the rock mechanical testing machine is not lower than +/-0.1 MPa.
3. The method according to claim 1, wherein the tunnel convergence displacement u in Step201 is measured by a high-precision digital display displacement meter, the measurement precision of the displacement meter is not lower than +/-0.01 mm, the monitoring frequency is adjusted according to the risk level, the low risk is 1 time/3 days, the medium risk is 1 time/day, the high risk is 1 time/2 hours, the extremely high risk is 1 time/30 minutes, the empirical coefficient k is adapted according to lithology, namely, granite lithology k takes 0.8-1.0, sandstone lithology k takes 0.6-0.8, mudstone lithology k takes 0.5-0.7, and k is verified and corrected by at least 3 groups of on-site convergence monitoring data.
4. The method of claim 1, wherein the treatment measures in Step3 are adjusted according to the risk level, the low-risk corresponding treatment measures are normal excavation without special treatment, the medium-risk corresponding treatment measures are additionally provided with harmful gas concentration monitoring points, the monitoring indexes comprise CO less than or equal to 24ppm and CH 4 less than or equal to 0.5%, the high-risk corresponding treatment measures are used for stopping excavation, single-hole pressure relief is adopted, the pressure relief rate is less than or equal to 0.01MPa/h, the extremely high-risk corresponding treatment measures are used for immediately evacuating personnel equipment, an emergency plan is started, and a combined treatment mode of cement-water glass double-liquid-slurry grouting plugging and drilling pressure relief is adopted.
5. The method of claim 1, wherein the risk classification in Step3 is such that R≥1.5 is a low risk, 1.0≤R <1.5 is a medium risk, 0.5≤R <1.0 is a high risk, and R <0.5 is an extremely high risk.
6. A dynamic prediction system for the sudden-by-accident risk of a high-pressure air bag of an adjacent tunnel for realizing the method of any one of claims 1 to 5, which is characterized by comprising a data acquisition module, a data processing and model calculation module and a risk early warning and visualization module; The data acquisition module comprises a geological radar, a drilling imager, a portable gas pressure recorder, a high-precision digital display displacement meter, a rock mechanical testing machine and a ground stress monitoring device, and is used for acquiring air bag parameters, rock mass parameters and engineering parameters in Step 1; The data processing and model computing module is internally provided with numerical computing software and a prediction algorithm and is used for executing rock wall stability computation, dynamic update of surrounding rock strength, rock wall resistance and damage capability computation, high-pressure air bag damage capability computation and sudden-impact risk index computation in Step2, and has an abnormal value rejection function, and the significance level alpha=0.05 by adopting a glabros criterion; The risk early warning and visualization module comprises a display, a grading audible and visual alarm and a data storage unit, and is used for displaying real-time risk grade, outputting early warning information and storing monitoring data and calculation results, and the risk early warning and visualization module also has a remote data transmission function, and can transmit real-time data to a remote monitoring platform to realize multi-terminal synchronous monitoring.
7. The system of claim 6, wherein the early warning signals of the classified audible and visual alarm are classified according to the risk level, namely, low risk of green light, medium risk of yellow light + intermittent audible and visual, high risk of orange light + continuous audible and visual, and extremely high risk of red light + high frequency audible and visual.

Description

Dynamic prediction method and system for sudden-by-accident risk of high-pressure air bags close to tunnel Technical Field The invention relates to the technical field of underground engineering safety, in particular to a dynamic prediction method and a system for sudden-by-burst risk of a high-pressure air bag close to a tunnel. Background With the expansion of construction scale of deep tunnels and large-burial-depth underground projects, high-pressure gas explosion disasters in non-coal-series strata (such as granite, sandstone and mudstone strata) have become key hidden hazards for threatening engineering safety. Different from coal measure stratum gas disasters, the non-coal measure stratum high-pressure air bags are formed by sealing and storing geological structure movements (such as earthquakes and multi-period extrusion), have the characteristics of small volume, high pressure and concentrated energy, and are characterized in that gas (such as methane, carbon dioxide, hydrogen sulfide and the like) is enriched in a trapping structure for a long time, and is easy to burst instantly after excavation disturbance, so that great losses such as construction equipment damage, casualties, construction period delay and the like are caused. The prior art has obvious defects: 1. The method is applicable to the scene limitation that the existing sudden-light risk prediction model, such as a coal and gas outburst prediction technology, is a model based on coal adsorptivity, and can not adapt to the characteristic of no adsorptivity and high pressure release of a non-coal stratum air bag aiming at coal stratum and depending on parameters such as coal porosity, gas adsorption amount and the like; 2. Ignoring dynamic attenuation of surrounding rock strength, namely generating plastic deformation due to stress redistribution after excavating a non-coal-series stratum rock mass, wherein the cohesive force of the surrounding rock and the internal friction angle are attenuated along with time (for example, the intensity attenuation rate reaches 5% -8% after excavating granite for 7 days), and the existing models adopt static intensity parameters to cause later risk misjudgment (for example, misjudgment of high risk as middle risk); 3. the risk quantification is inaccurate, the existing method mostly adopts qualitative description (such as possible bursting and low probability bursting), does not establish quantitative relation of anti-damage capability and damage force, and cannot provide specific threshold values (such as when to release pressure and how much pressure release rate) for construction treatment. Therefore, a high-pressure airbag burst prediction technology which is adaptive to a non-coal-series stratum and considers dynamic attenuation of surrounding rock strength and quantifiable risk is needed, and the blank of the prior art is filled. Disclosure of Invention The invention aims to overcome the defects of the prior art, provides a dynamic prediction method and a system for the sudden-rise risk of the high-pressure air bags of the adjacent tunnels, which can comprehensively consider the pressure, the volume, the rock wall state and the dynamic attenuation of the surrounding rock strength of the high-pressure air bags, and is particularly suitable for deep tunnels of non-coal formations and underground projects with large burial depths (such as traffic tunnels, hydraulic tunnels, underground pipe galleries and the like), and can dynamically predict the sudden-rise risk of gas when the high-pressure air bags are closed in tunnel construction, thereby providing accurate decision basis for engineering disaster prevention and reduction. The technical scheme of the invention is as follows: The invention provides a dynamic prediction method for a sudden-by-burst risk of a high-pressure air bag close to a tunnel, which comprises the following steps: Step1, parameter acquisition, namely acquiring air bag parameters, rock mass parameters and engineering parameters; The parameters of the air bag comprise the pressure P g and the equivalent radius R g of the air in the air bag; The rock mass parameters comprise initial strength parameters (cohesive force c 0, internal friction angle phi 0), residual strength parameters (cohesive force c r, internal friction angle phi r), elastic modulus E, poisson's ratio v and attenuation coefficients (alpha, beta); The engineering parameters comprise the initial thickness D 0 of the rock wall between the tunnel and the air bag, the equivalent radius R tun of the tunnel excavation section, the time t after the excavation, the supporting strength sigma sup and the ground stress (vertical ground stress sigma v and horizontal ground stress sigma h); Step2, real-time analysis phase: Step201 calculation of the stability of the rock wall based on the on-site monitored tunnel convergence displacement u by empirical relationship Calculation of equivalent plastic strain of the rock wall be