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Urban Geologic Mapping
Published in Daniel T. Rogers, Urban Watersheds, 2020
After examining the depositional layers from excavation pits as shown in Figure 5.4, evaluating and recording the strike and dip of the depositional units is required before a three-dimensional map can be developed (Lahee 1961). Strike refers to the attitude or trend of a particular deposit. For instance, if a geologist were mapping a sandy beach deposit from an ancient lake and recorded the trend of the deposit at several locations, the geologist would be able to determine the size of the lake. The Strike of a deposit, outcrop, or other planar feature is represented on a geologic map as a short straight-line segment oriented parallel to the compass direction of the strike. The dip is defined as the angle at which the geologic deposit, feature, or structure is tilted relative to the horizontal plane. The dip is represented on map as a line segment perpendicularly attached to the strike symbol.
Wedge failure
Published in Duncan C. Wyllie, Rock Slope Engineering, 2017
Chapter 7 dealt with slope failure resulting from sliding on a single planar surface dipping out of the face, and striking parallel or nearly parallel to the slope face. It was stated that the plane failure analysis is valid if the strike of the failure plane is within ±20° of the strike of the slope face. This chapter is concerned with the failure of slopes containing discontinuities striking obliquely to the slope face where sliding of a wedge of rock takes place along the line of intersection of two such planes (Figure 8.1). Wedge failures can occur over a much wider range of geologic and geometric conditions than plane failures. Therefore, the study of wedge stability is an important component of rock slope engineering. The analysis of wedges has been extensively discussed in geotechnical literature, and this chapter draws heavily upon the work of Goodman (1964), Wittke (1965), Londe (1965), Londe, Vigier and Vormeringer (1969, 1970) and John (1970).
Engineering Seismology Overview
Published in Hector Estrada, Luke S. Lee, Introduction to Earthquake Engineering, 2017
The fault slip is used to classify faults depending on the direction of the movement of rocks on one side relative to the other side; vertical movement is known as dip-slip, while horizontal movement is known as strike-slip. These terms correspond to the definition of the angles used to describe the direction of fault movement. As discussed in Section 1.2.3, faults occur along the edges of tectonic plates (or their interior, which is much less common). Dip-slip faults are further subdivided based on the relative vertical movement of the tectonic plates: normal faults occur at plate boundaries where tectonic plates spread apart at divergent zones causing the hanging wall to move down relative to the footwall, while reverse faults occur at plate boundaries where tectonic plates collide at convergent zones causing the hanging wall to move up relative to the footwall; see Figure 2.2. Thrust faults are reverse faults with a small dip angle. Faults along oceanic ridges are normal, resulting in the lengthening of the crust, as shown previously in Figure 1.11, whereas those along subduction zones are reverse, resulting in the shortening of the crust. When these faults break through to the surface, surface rupture, they produce an exposed steep slope known as the fault’s scarp; see Figure 2.2.
Comparison and analysis of different methods for structural planes measuring in underground roadways
Published in Energy Sources, Part A: Recovery, Utilization, and Environmental Effects, 2023
Hongdi Jing, Xiaobo Liu, Anlin Shao, Liancheng Wang
The rock strike is the direction of the intersection of the rock layer and the horizontal plane. When measuring the rock strike, the long side of the compass is closely attached to the layer, the bubble of the chassis level is centered, and the value indicated by the pointer is the strike of the rock layer. Because the rock strike is a straight line, it can extend on both sides. The readings of the north and south needles of a compass are the extension of the line. For example, NE30° and SW210°can both represent the direction of the rock strike.