Circular surface sliding

Another case of sliding on a circular surface is considered. The block system in this case is shown in Figure 3a along with the piezometric surface. The bottom and left boundaries of the slope shown are fixed in their respective normal directions, and the other boundaries are free. The material constants for all the blocks are Young s modulus E... 

When the slope of rock is soft and structural plane is in the opposite direction against the slope plane, slope will slide along a curved surface of a slide, rather than flat sliding. Most circular surface soil slope is sliding, therefore, this paper calculates the soil slope stability factor with Bishop method (LI 2006). 

Sliding along circular surfaces (rotational stability)... 

A circular failure surface is assumed and the soil encompassed by such surface is divided into many slides divided by vertical surfaces. Eor each, it is possible to calculate the active moments caused by the thrusts of the soil and the resisting moments resulting from the frictional and/or cohesive forces and the tensile strength in the geotextile layers (Fig. 15.18) the FS is calculated as the ratio of the sum of the resisting moments and the sum of the active moments. Numerous circular surfaces are investigated for each, the FS is calculated as follows (Eq. [15.45]) ... 

In the two-dimension technique, the reservoir (at best circular) of one reagent is surrounded by a uniformly thick layer of gel placed at the surface of a glass slide (for example, in a Petri dish). A thin layer contains the other reagent simple diffusion). Alternatively, both reagents diffuse from similar reservoirs into a gel layer containing neither of them double diffusion). 

In a second test of spray pattern, special slides were obtained from Erie Scientific, Inc. (Portsmouth, NH) that were evenly coated over their entire surface with a paint-like coating that does not make fluids bead up, nor does it allow bleeding of applied fluids. These slides were loaded onto the platen, and the instrument was programmed to spray dye onto all three positions of each slide. The slides were then kept on the machine until all water had evaporated, leaving the dye residue on the coating in the original area sprayed. This test resulted in circular spray patterns over... 

Measuring the force (the weight) needed to break away a body from the liquid surface is the basis for many variations of the detachment method. The body may be in the form of a rod with a circular base (Pin detachment method), a rod with a rectangular base (Wilhelmy slide method), a horizontal circular ring (Ring method), etc. The different forms of the detachment method have been used for surface tension measurement of liquids from room temperature up to approximately 1000°C. It is evident that the detachment methods can be used only in cases when the liquid wets the measuring body. 

Figure 3a. Rock slope model with circular sliding surface and piezometric surface.

By the abovementioned way of measuring the viscosity, that is, sliding plate, the absolute or otherwise known as dynamic viscosity (q or q) is measured. At this point, it should be mentioned that the relative movement of the two solid surfaces could also be rotary such as in a system of cylindrical container and rotating cylinder, or of a flat surface (plate) with a rotating cone, or of a flat surface (plate) with a rotationally oscillating circular plate. All these systems are basically the different types of viscosity measuring devices that measure dynamic or absolute viscosity (dynamic viscometers). 

In true slides, the movement results from shear failure along one or several surfaces, such surfaces offering the least resistance to movement. The mass involved may or may not experience considerable deformation. One of the most common types of slide occurs in clay soils where the slip surface is approximately spoon-shaped. Such slides are referred to as rotational slides. They are commonly deep-seated (0.15 depth/length < 0.33). Although the slip surface is concave upwards, it seldom approximates to a circular arc of uniform curvature. For instance, if the shear strength of the soil is less in the horizontal than vertical direction, the arc may flatten out if the soil conditions are reversed, then the converse may apply. What is more, the shape of the slip surface is influenced by the discontinuity pattern of the materials involved (Bell and Maud, 1996). 

For the landslides consists of loose unconsolidated sediment and are without definite sliding surface, circular slip method should be employed to search for the minimum safety factor. 

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