The sliding distance and fault distance of a fault are the general names of the relative displacements of two plates of the fault. At present, there are two methods to study slip distance and fault distance: one is to use equivalent points, and the other is to use equivalent layers. The equivalent point is a point before the fault occurs, and two points are formed after the fault action, which is called the equivalent point; The equivalent layer is a continuous layer before the fault occurs, and becomes two layers after the fault is displaced, which are distributed on both sides of the fault. These two layers are called equivalent layers.

(1) sliding distance

Slip distance refers to the actual displacement distance between two rock strata or rock masses of a fault, and refers to the actual distance between two corresponding points after a fault dislocation.

(1) Total sliding distance (also called true fault distance): refers to the distance corresponding to the true displacement between two points (ab in Figure 6-3 Ⅰ).

(2) Strike-slip distance: refers to the component of the total slip distance on the strike line of the fault plane (ac in Figure 6-3 I). The angle between strike-slip distance and total slip distance ∠cab is the total slip distance or the lateral angle of fault scratch line.

(3) Oblique slip distance: refers to the component of the total slip distance on the oblique line of the fault plane (bc in Figure 6-3 I).

(4) Horizontal sliding distance: refers to the projection of the total sliding distance on the horizontal plane (am in Figure 6-3 I).

The total slip distance, strike slip distance and oblique slip distance form a right triangle on the fault plane.

Although the fault distance measured by equivalent point is very accurate, it is difficult to determine the corresponding point in practical work, so this method is rarely used.

Figure 6-3 Sliding distance and fault distance of faults (according to Sun Chao, 1990)

Ⅰ—— stereogram of fault displacement; Ⅱ —— section perpendicular to stratum strike; Ⅲ —— AB section perpendicular to fault strike —— total sliding distance; AC- strike sliding distance; CB-inclined sliding distance; Am-horizontal sliding distance; Ho—— fault distance of stratum; H' o '—o '- o'-apparent stratigraphic fault distance; Hg = h' g'-fault distance of vertical stratum; HF- horizontal formation fault distance; H' f '—f '- f'-fault distance of apparent horizontal stratum; α-stratum dip angle; Ω —— Apparent dip angle of stratum

(2) Fault distance

Fault distance refers to the relative distance between equivalent layers of staggered strata on two plates. Based on the equivalent layer on the vertical section, there are two measurable fault distances:

1. Fault distance calculated from vertical stratum strike profile (Figure 6-3 Ⅱ)

(1) stratigraphic fault distance (ho): the vertical distance between equivalent layers on both sides of the fault and the same layer.

(2) Vertical stratum fault distance (hg): the vertical distance between equivalent layers on both sides of the fault and the same layer.

(3) Horizontal stratigraphic fault distance (hf): the horizontal distance between equivalent layers on both sides of the fault at the same height and the same plane. In a normal fault, the horizontal stratigraphic fault distance represents the horizontal distance between equivalent layers on both sides of the fault; In the reverse fault, the fault distance of horizontal strata represents the horizontal distance covered by equivalent layers on both sides of the fault.

2. Fault distance measured on vertical fault strike profile (Figure 6-3 Ⅲ)

The fault distance calculated on the vertical fault strike profile also includes stratigraphic fault distance, vertical stratigraphic fault distance and horizontal stratigraphic fault distance. However, because the strike of the staggered strata is not parallel to the strike of the fault, the horizontal and vertical strata dislocations increase correspondingly, except that the vertical strata dislocations do not change with the profile direction, which are called apparent strata dislocations (H ′ o ′) and apparent horizontal strata dislocations (H ′ f ′) respectively.

On the section perpendicular to the stratigraphic strike, the mathematical relationship between stratigraphic fault distance and vertical stratigraphic fault distance is as follows:

Ho=hg cosα hg=hf tanα

ho=hf sinαhf=hg cotα

Where α is the dip angle of rock stratum.

In mining, in order to design the length of vertical shaft and drift, fault terms such as flat fault and drop are often used. The concepts of flat fault and drop are not unified. Generally, on the section perpendicular to the fault strike, the vertical component of the dip fault distance is called drop, and the horizontal component of the dip fault distance is called flat fault (Figure 6-4).

Figure 6-4 Fault dislocation (YZ) and drop (XY)