初论擦痕性质

用擦痕作为研究断裂两盘岩体相对位移的主要依据已有几十年的历史。大多数人认为,它只代表岩体最后一次运动时所留下的遗迹。但也有人把擦痕作为确定断裂两盘岩体活动方向的唯一标志,还有人用断裂面上不同方向的擦痕确定断裂多期活动的先后次序,为此,野外观察者常是用手抚摸断裂面上的平滑度,得出断裂两盘岩体的相对位移方向。

A PRELIMINARY NOTE OF THE BEHAVIOUR FOR SCRATCH

1)The scratch is a kind of trace which have been retained by the last fault action, but it isn’t main evidence to prove actional direction of stresses during faulting. We think that most of step scratches on surface of fault is related to phenomenon of stress relaxation.2)In the light of observation of field and laboratory results of model experiment, we think that most of step scratches are characterized by compact feather fractures in cross section. We can accurately defined movement direction of fault based on arrangement pattern of the feather fractures.3)Although it is unreliable that displacement directions of rock masses on two sides of fault are determined by the scatch, it is necessary for careful obsevertion the phenomenon in field and under microsop because of the scratch are characterized by orientation arrangement.4)The scratch represents only the behaviour of surface of fault, so that it is necessary to careful study internal behaviour of rock masses on two sides of fault.5)Generally, the step scratch is caused by tensile stress acted on the rock masses of two sides of fault.