Reconstruction of 3D stress field in coal–rock mass by solving inverse problem using tomography data

Nazarova, Larisa; Nazarov, L. A.; Protasov, M.

doi:10.1134/s1062739116041010

Cited by 13 publications

(7 citation statements)

References 16 publications

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“…This allows verifying the model in terms of forensic analysis [14] forecasting the number and total energy of man-triggered events on the distribution of stresses, calculated in accordance with the long-range mining plan. In [15,16], new approach to modeling of current stressed and deformed state of a deposit mined was theoretically justified by the data of passive and/or active tomography and experiments on the determination of empirical dependence of longitudinal waves velocity on average stress.…”

Section: Introductionmentioning

confidence: 99%

Concerning the capability of monitoring the condition of coal bed by tomography based upon the representation of object model using Chebyshev polynomials

Nazarova¹,

Nazarov²,

Protasov³

et al. 2018

E3S Web Conf.

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3D geomechanical model of “Vorkutinskaia” mine, which allowed describing the development of stressed and deformed state of coal bed rock mass, has been developed and realized in numbers. Using empirical dependences of longitudinal waves velocity V on mean stressσ established by laboratory testing data, 3D distribution of V has been plotted. First arrival time tomography task, based upon the approximation of a bed geometrical model by Chebyshev polynomials, in order to give appraisal to the applicability for bed velocity structure reconstruction, has been analysed. With the use of data on dynamic events, registered by permanent stations, the object tomography has been prepared and 3D field of elastic waves velocities in highlighted part of area under study. It enables essential opportunity of stress state, if functions V (σ) for rocks building up the massif are known.

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Section: Introductionmentioning

confidence: 99%

Concerning the capability of monitoring the condition of coal bed by tomography based upon the representation of object model using Chebyshev polynomials

Nazarova¹,

Nazarov²,

Protasov³

et al. 2018

E3S Web Conf.

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“…Cylindrical samples were subjected to uniaxial compression by a standard procedure [14], as a result of which the static Young's modulus E = 9.2 GPa and the Poisson's ratio   0.21 (average values) were determined, which corresponds to the same parameters for coals [15,16,17]. At each loading step an ultrasonic time-pulse method with UD2M-PN flaw detector was used to determine the velocity of longitudinal waves V. The processing of the obtained data by the original technique [18,19] made it possible to obtain an experimental dependence…”

Section: Methodsmentioning

confidence: 99%

“…Tomography of the sample was carried out using the original iterative procedure [18,19], the stability of which is ensured by the expansion of the solution at intermediate steps in a specially constructed basis [20]. In Figure 1, the illumination domain I is highlighted for the selected observation system {S m }.…”

Section: Reconstruction Of Speed Distribution Of Longitudinal Wavesmentioning

confidence: 99%

Experimental substantiation of acoustic method for determination of “coal bed - country rock” contact relations based on boundary inverse problem solution

et al. 2018

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The article describes the acoustic method developed by the authors to determine the contact conditions between coal seam and host rocks on the basis of boundary inverse problem solution. Justification of the applicability of the method is made by means of physical modeling, in which samples from the model material were subjected to step-by-step uniaxial loading with simultaneous ultrasonic sounding using a multichannel scheme. In this case, various friction conditions were set for different samples at the “sample-plate of the press” interface. Based on the results of sounding, the distribution of velocities in the illuminated domain of the sample was reconstructed using tomographic processing. The array of data obtained as a result of acoustic tomography was used as input data to solve the inverse problem. As a result of the solution of the inverse problem, it was shown that the appearance of slip regions at the boundaries of the sample generates tensile stresses, the magnitude of which reaches 0.8 from the axial load. The developed method makes it possible, on the basis of acoustic measurements, to identify areas with a reduced coefficient of friction between the coal seam and the host rocks, the presence of which may be the reason of dangerous dynamic phenomena.

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“…where ξ is a random variable uniformly distributed over [-1,1]. Using the original code [49], we perform tomography by * { } pq t , find the distribution of the velocities V * (x,y) in the illuminated domain I (Fig. 5) and, finally, from ( 5), obtain the input data…”

Section:  mentioning

confidence: 99%

Method for weak zones location at the coal-bed – host rock joint relative to the problem of sudden outbursts: theory and laboratory experiment

Nazarov

2022

Frattura Ed Integrità Strutturale

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Within the framework of a geomechanical model that describes the deformation of a rock mass during the subhorizontal coal-bed extraction, the mechanism for the formation and implementation of a sudden outburst is substantiated: as working face gets close to the weak zone of coal-bed – host rock joint, areas of tensile stresses arise, which creates the prerequisites for face space spalling and coal loss with methane. The inverse problem of determining the conditions at the horizontal boundaries of a coal-bed is formulated and solved using tomography data (longitudinal wave velocity V distribution) and the empirical dependence of V on the mean normal stress σ. Lab tests results on stepwise compression of parallelepipeds made of artificial geomaterials are presented. Tomography of the specimens was performed by acoustic sounding data, and the distribution of velocities V* was found. Using the pre-established empirical dependence V(σ) for geomaterial, the distribution σ*=V-1(V*) in the specimen was calculated, which served as input data for inverse problem of determining the shear stresses σxy at the “specimen faces – press platens” joints. Lab data inversion confirmed the possibility of identifying weak zones of the boundaries where σxy=0. These zones are associated with probable nucleus of failure and sudden outbursts.

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Reconstruction of 3D stress field in coal–rock mass by solving inverse problem using tomography data

Cited by 13 publications

References 16 publications

Concerning the capability of monitoring the condition of coal bed by tomography based upon the representation of object model using Chebyshev polynomials

Concerning the capability of monitoring the condition of coal bed by tomography based upon the representation of object model using Chebyshev polynomials

Experimental substantiation of acoustic method for determination of “coal bed - country rock” contact relations based on boundary inverse problem solution

Method for weak zones location at the coal-bed – host rock joint relative to the problem of sudden outbursts: theory and laboratory experiment

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