Analysis of calculation models while solving geomechanical problems in elastic approach

Shashenko, Oleksandr; Hapieiev, Serhii; Шаповал, Владимир Григорьевич; Khalymendyk, Oleksii

doi:10.29202/nvngu/2019-1/21

Cited by 9 publications

(17 citation statements)

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“…According to the girders hypothesis (Yakobi, 1987;Borisov, 1980;Viktorov, Iofis, & Goncharov, 2005;Shashenko, Pustovoytenko, & Sdvizhkova, 2016), let us assume that in the stope face, the coal seam roof is being deformed and destroyed like girders. The stability of roof outcropping in the area adjacent to the longwall face, significantly depends on the degree of its preliminary fracturing and the deflection value, when the separate blocks of the stratified rock stratum operate as hinges (Borisov, 1980;Khalymendyk & Baryshnikov, 2018).…”

Section: Methodsmentioning

confidence: 99%

“…In conventional methods for controlling the rock pressure by complete collapsing or holding the roof on chocks, the support used in the stope face is not always able to withstand the side rocks displacement, especially in case of sudden collapse of the stratified stratum of the hinges (Viktorov, Iofis, & Goncharov, 2005;Shashenko, Pustovoytenko, & Sdvizhkova, 2016). Currently used methods of protecting the drifts by various structures made of wood (prop stays cluster, breakerprop row) or whole coal, also do not always provide reliable protection of mine workings from dangerous rock pressure manifestations.…”

Section: Introductionmentioning

confidence: 99%

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Phenomena of stability of the coal seam roof with a yielding support

Podkopaiev¹,

Gogo²,

Yefremov³

et al. 2019

Min. miner. depos.

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Purpose. Determining the conditions and parameters for ensuring the stability of the coal seam roof with a yielding support in the area adjacent to face and behind it under the influence of dynamic loads based on the analytical and laboratory studies. Methods.To achieve the purpose set, analytical studies have been carried out using the basic principles of the theory of elasticity and vibrations, the hypothesis of girders and the hinged-block displacement of the stratified rock stratum. Also, the laboratory studies of models from equivalent materials have been performed, in which the coal seam roof is presented in the form of a girder having a yielding support with variable rigidity from the filling material under dynamic load.Findings. As a result of performed studies, the phenomenon has been determined that the condition for the stability of the coal seam roof is a geometric parameter that reflects moving of the girder with a yielding support, under the force impact of a falling load with a known mass and the physical-geometrical characteristics of the deformable system. It has been determined that as a result of a change in the spans length, a change in the flexural rigidity of the girder occurs, which means that the yield influence of the same supports on the stability of the coal seam roof is different. The values have been set and the relationship has been studied of the physical-mechanical characteristics of the filling mass as a yielding support.Originality. It has been proven scientifically that the stress-strain state (SSS) of a system in which the coal seam roof is studied as a girder depends on the physical-geometrical characteristics of the system, as well as the type and place of applying the external load, in case when the law of the girder movement in time is determined.Practical implications. The effective supporting of the undermined rock stratum in the working part of the longwall face and behind the face is achieved by placing the yielding supports in the mined-out space or by using the backfill in the mined-out space while conducting the stope operations, thus, increasing the efficiency of measures to protect the labour of miners in coal mines.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phenomena of stability of the coal seam roof with a yielding support

Podkopaiev¹,

Gogo²,

Yefremov³

et al. 2019

Min. miner. depos.

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“…where s z is the vertical normal stress; τ xy , τ xz , τ yz are the tangential stresses; ξ = ν/(1-ν) is the rebuff ratio; v is the Poisson coefficient [1,14]. When the soil approaches its limiting state, its Poisson coefficient tends to a value equal to 0.5.…”

Section: Materials and Research Methods Aimed At Taking Into Considermentioning

confidence: 99%

“…The prerequisite for an extremum is to meet the conditions: Since the equation system (16) has no valid roots, there is no any extremum of function (17) for variables α and z at all. Therefore, solutions (12), (14) and (15) are not mathematically rigorous. To take into consideration the non-linearity of dependence of the Mohr-Coulomb envelope, we shall use the condition of strength proposed by A. Shashenko, which, in a one-dimensional case, takes the form [1,15]:…”

Section: Materials and Research Methods Aimed At Taking Into Considermentioning

confidence: 99%

Determining the influence of physical nonlinearity of soil strength properties on the estimated base resistance

Shashenko

Шаповал

Kovrov

et al. 2019

EEJET

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Розглянуто перспективність використання нелінійних моделей міцності при визначенні початкового критичного навантаження на ґрунт, а також нормативного та розрахункового опорів основи, що дозволяє зменшити трудомісткість процесу визначення міцнісних властивостей ґрунтів. На підставі аналізу та узагальнення результатів теоретичних досліджень геомеханічних процесів з використанням аналітичних математичних методів отримані модифікації формул, які призначені для визначення початкового критичного навантаження на ґрунт, а також нормативного та розрахункового опорів основи. Встановлено взаємозв'язок міцності, зокрема питомого зчеплення і кута внутрішнього тертя, що входять в умови міцності Кулона-Мора та А. Шашенка, що дозволяє вдосконалити методику розрахунку зовнішніх навантажень на ґрунт. Проаналізовано залежності критичних навантажень на основу від середнього тиску під підошвою фундаменту в діапазоні тисків Р = 100...500 кПа з використанням умов міцності Кулона-Мора та А. Шашенка. Встановлено, що при використанні загальноприйнятих розрахункових формул для визначення критичних навантажень на основі обов'язково слід враховувати діапазон тисків, при яких визначалися властивості міцності ґрунту. При цьому використання критерію міцності А. Шашенка для визначення критичних навантажень на основу дозволяє коректно врахувати вплив на них середнього тиску під підошвою фундаменту. На відміну від залежностей, які використовуються в даний час в українських, білоруських, російських та нормативних документах інших країн, отримані формули дозволяють враховувати залежності міцнісних властивостей ґрунту від середнього тиску на ґрунт під підошвою фундаменту. Отримані результати дозволяють підвищити достовірність визначення початкового критичного навантаження на ґрунт, а також нормативного та розрахункового опорів основи. Це досягається за рахунок урахування нелінійності обвідної граничних кіл Мора з використанням умови міцності А. Шашенка Ключові слова: критерії міцності Кулона-Мора і А. Шашенка; навантаження на ґрунт, зчеплення, кут внутрішнього тертя

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“…The finite element method makes possible, with an adequate problem formulation and with setting initial data, to reflect the stress state formation of the massif [46,47], similarly to natural conditions [48,49]. Therefore, this article is supposed to investigate the stability of producing wells in the coal and rock massif with the use of the computer simulation based on the finite element method [50,51].…”

mentioning

confidence: 99%

Predicting the producing well stability in the place of its curving at the underground coal seams gasification

et al. 2019

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The relevant issues have been studied of ensuring the stability of producing wells in the place of their curving when uncovering the mining extracted area for the underground gas generator operation. It is emphasized that the design planning of efficient operation of underground gas generators in downhole gasification technology is impossible without consideration of the stress state of the rock massif, which can lead to a danger of the wellbore cutting and emergency shutdown of the technological system operation. The parameters of geomechanical models have been developed and substantiated for the study of the stress state of the “rock massif – producing well” system under the conditions of the Lviv-Volyn coal basin. A computer simulation has been performed of change in the stress state of a laminal massif around a well with a curvature radius in the range of 5 – 25 m with the use of the finite element method. The exponential function has been revealed of the tensile stresses value in the roof of the seam from the angle of the producing well entry into the coal seam. It is recommended the rational angle of a well entry into the coal seam, which is in the range of 21 – 28 degrees, and an appropriate curvature radius will be 5 – 10 m.

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Analysis of calculation models while solving geomechanical problems in elastic approach

Cited by 9 publications

References 0 publications

Phenomena of stability of the coal seam roof with a yielding support

Phenomena of stability of the coal seam roof with a yielding support

Determining the influence of physical nonlinearity of soil strength properties on the estimated base resistance

Predicting the producing well stability in the place of its curving at the underground coal seams gasification

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