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通过理论解析并结合数值模拟试验,研究了裂纹倾角对受压裂纹近周第一主应力场和剪应力场的影响。为了能够反映原生裂纹周边的次生裂纹特征,根据原生裂纹近周应力场提出了可描述裂隙岩体中次生裂纹起始位置、起始方向、发展方向的应力极值线的概念。从理论上对应力极值线进行了定义,并通过典型的数值试验分析了应力极值线随裂纹倾角变化的特征与演变过程,进一步从应力极值线角度描述了受压原生裂纹的次生张性裂纹和次生剪切裂纹的特征。研究结果表明:随裂纹倾角增大第一主应力极值线与原生裂纹相交点从裂纹中部向裂纹端部移动,但剪切应力极值线与裂纹相交点始终位于裂纹端部;第一主应力极值线在与原生裂纹相交处垂直于原生裂纹,但最终方向与压力方向平行;剪应力极值线始终与原生裂纹大致共面。研究结果对认识裂隙岩体试样破坏模式、解释张性次生裂纹和剪切次生裂纹的起裂及发展机理有一定的借鉴意义。
Through theoretical analysis and numerical simulation, the influence of crack dip angle on the first principal stress field and the shear stress field in the vicinity of compression fractures was studied. In order to reflect the characteristics of secondary cracks around primary cracks, the concept of stress extrema describing the starting position, starting direction and development direction of secondary cracks in fractured rock mass is proposed according to the near-field stress field of primary cracks. The stress extremum line is defined theoretically. The characteristics and evolution of the stress extremum line with crack dip angle are analyzed through typical numerical experiments. The secondary stress cracks are described from the viewpoint of stress extremum Characteristics of tensile and secondary shear cracks. The results show that the intersection of the first principal stress extremum and the primary crack moves from the middle part to the end part of the crack as the inclination of the crack increases, but the intersection of the shear stress extremum line and the crack is always located at the crack end. The stress extremum line is perpendicular to the primary crack at the intersection with the primary crack, but the final direction is parallel to the pressure direction. The extreme shear stress line is always coplanar with the primary crack. The results of the study have certain reference significance for understanding the failure mode of the fractured rock mass specimen, explaining the initiation and development mechanism of the secondary tensile and shear secondary cracks.