â Ôàêóëüòåò ãðàaeäàíñêîãî ñòðîèòåëüñòâà, ÑÀÄÐÀ èíñòèòóò, Òåãåðàí, Èðàí ã Ñû÷óàíüñêèé óíèâåðñèòåò, ×ýíäó, Êèòàé Èññëåäîâàíî âëèÿíèå ðàçúåäèíåíèÿ ñîåäèíåíèÿ ïðè ñäâèãå ïëîñêîãî íåñòàáèëüíîãî ñîåäèíåíèÿ ïîä äåéñòâèåì èíòåíñèâíîé íîðìàëüíîé íàãðóçêè ñ èñïîëüçîâàíèåì ïðîãðàììíîãî îáåñïå÷åíèÿ PFC2D. Ïåðâîíà÷àëüíî êàëèáðîâêà PFC2D ïðîâåäåíà íà îñíîâå ýêñïåðèìåíòàëüíûõ äàííûõ äëÿ ñîãëàñîâàíèÿ ñ ìîäåëèðóåìûì ÷èñëîâûì ðåçóëüòàòîì. Äîñòîâåðíîñòü ìîäåëèðóåìûõ ìîäåëåé ïðîâåðåíà ïðè ñðàâíåíèè ñ ðåçóëüòàòàìè ïðÿìûõ èñïûòàíèé íà ñäâèã, âûïîëíåííûõ íà íåñòàáèëüíûõ ñî÷ëåíåííûõ ôèçè÷åñêèõ ìîäåëÿõ. Áëàãîäàðÿ ÷èñëîâîìó ïðÿìîìó èñïûòàíèþ íà ñäâèã ïðîöåññ ðàçðóøåíèÿ áûë îòìå÷åí âèçóàëüíî, è ðàçðóøåííûå îáðàçöû îòáèðàëèñü ïîäîáíûìè ýêñïåðèìåíòàëüíî íàáëþäàåìûì òåíäåíöèÿì. Äèñêðåòíîå ìîäåëèðîâàíèå ýëåìåíòà ïîêàçûâàåò, ÷òî íà ðàçðóøåíèå îáðàçöà ãëàâíûì îáðàçîì âëèÿåò ðàçúåäèíåíèå ñîåäèíåíèÿ, â òî âðåìÿ êàê ïðî÷íîñòü ïðè ñäâèãå ñâÿçàíà ñ ìîäåëüþ ðàçðóøåíèÿ è ìåõàíèçìîì ðàçðóøåíèÿ.Êëþ÷åâûå ñëîâà: ïðîãðàììíîå îáåñïå÷åíèå PFC2D, íåñòàáèëüíîå ñîåäèíåíèå, ðàçúåäèíåíèå ñîåäèíåíèÿ, òðåùèíû ñäâèãà è ðàñòÿaeåíèÿ.
Introduction. The rock mass is composed of non-persistent joints and intact rock [1].The shear sliding of non-persistent joints is important factor controlling the mechanical behavior of rock masses [2]. Therefore, a study on the shear failure behavior of nonpersistent joint can provide a good understanding of both local and general rock instabilities, leading to an improved design for rock engineering projects. Lajtai [3,4], tensile wing cracks were found to first appear at the tips of horizontal joints, followed by the secondary shear cracks propagating towards the opposite joint. Savilahti et al. [5] did some further study on the specimens with jointed rock under direct shear testing where the joint separation varies in both horizontal and vertical directions and joint arrangement changes from non-overlapping to overlapping using modelling material. The coalescence patterns for specimens indicated that, the jointed rock failed in mixed and tensile modes for non-overlapping and overlapping joint configurations, respectively. Wong et al. [6] studied
In this study, ultrasonic waves recorded during direct shear experiments on rock joints were employed to investigate the shear failure processes. Three types of wave attributes were systematically observed prior to the shear failure of the rock joints: (a) maximum in the amplitude of the transmitted wave, (b) maximum in the dominant frequency of the transmitted wave, and (c) maximum in the velocity of the wave. Different processes occurring during both frictional sliding and stick‐slip oscillations were identified in this study: (a) interseismic phase and (b) preseismic phase. The interseismic phase is associated with elastic loading, very small local slip rate, and increasing ultrasonic transmission along the contact surfaces. The rock joint is considered locked, and the increase in ultrasonic transmission represents an increase in the real (true) area of contact because of interlocking and contact aging. The start of the preseismic phase is marked by the onset of precursors for different regions of the rock joint. Following the interseismic and preseismic phases, coseismic phase occurs. The coseismic phase begins with the reduction in the applied shear stress and is associated with an abrupt increase in the local slip rate. The reductions in transmitted amplitude, wave velocity, and dominant frequency all indicate the preseismic phase when the asperity contacts begin to fail before macroscopic frictional sliding. The observation of the preseismic phase in both the loading phase leading to stable sliding and stick‐slip failure modes suggests that microphysical processes of fault weakening may share key features for these two failure modes.
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