The tectonic stress is the stress caused by the movement of the crustal structure in the rock mass. Tectonic stress includes the stress generated in the underground rock during the occurrence of geological formations; and the residual geological tectonic movements remaining inside the rock mass. From the engineering point of view, paleo-tectonic stress, neotectonic stress and structural internal stress formed during rock formation belong to tectonic stress. The basic characteristics of tectonic stress are mainly horizontal stress, with obvious directionality and regionality.
The horizontal stress is composed of the horizontal stress caused by the self-weight of the rock layer, the frictional force and cohesion between the rock layers, and the horizontal tectonic stress. The tectonic stress has obvious directionality. The angle between the axial direction of the roadway and the direction of the tectonic stress is different. The horizontal stress concentration of the surrounding rock of the roadway is very different. In areas where the influence of tectonic stress is strong, the direction of roadway layout should be emphasized, and the relationship between the direction of the roadway and the direction of tectonic stress should be properly adjusted to reduce the influence of tectonic stress on the stability of surrounding rock of the roadway.
Figure 6-6 Stress distribution of surrounding surrounding rock under axial parallel and vertical tectonic stress of roadway
A—the axial parallel structural stress of the roadway; b—the axial vertical structural stress of the roadway
The calculation results show that the structural stress has the least influence on the stability of the roadway when the axial direction of the roadway is parallel with the direction of the structural stress. When the axial direction of the roadway is perpendicular to the direction of the structural stress, the influence is greatest. The influence of tectonic stress on the stability of the roadway mainly changes with the square value of the sine of the angle α. If the angle α is less than 25 0 to 30 0 , the influence of tectonic stress on the stability of the roadway does not change significantly. Under the condition of axial parallel and vertical tectonic stress direction of the roadway, the surrounding tangential and radial stress distribution is shown in Figure 6-6.
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