Slide blocking

The coefficient of friction /x between two solids is defined as F/W, where F denotes the frictional force and W is the load or force normal to the surfaces, as illustrated in Fig. XII-1. There is a very simple law concerning the coefficient of friction /x, which is amazingly well obeyed. This law, known as Amontons law, states that /x is independent of the apparent area of contact it means that, as shown in the figure, with the same load W the frictional forces will be the same for a small sliding block as for a laige one. A corollary is that /x is independent of load. Thus if IVi = W2, then Fi = F2. 

Figure C2.9.2 Shear force versus time during (a) sliding and (b) stick-slip motion. The motion of the surface beneath the sliding block of figure C2.9.1 is at constant velocity.

Capacity reduction of the twin-screw compressor is effected by a sliding block covering part of the barrel wall, which permits gas to... 

Place the covered slides on a PCR thermal cycler with slide blocks or a hybridization instrument. 

Fig. 12.6. Inertial stepper, (a) schematic, (b) actual design. A load (1) is carried by a sliding block (2), which is riding on a rail (3). The rail (3) is mounted on a mobile frame consisting of two elastic metal plates (4) and (5), a base plate (6), and a piezoelectric tube (7). By applying a sawtooth voltage on the piezo tube, the sliding block (2) moves back or forth in steps. (Reproduced from Pohl, 1987, with permission.)...

Sliding-Block Friction Test. In the sliding-block friction test (Fig 1), a sample is subject to frictional forces when clamped between two prepared steel surfaces (Ref 2). The upper sliding block is constrained to move horizontally over the lower fixed block by guides. A pedal-operated mechanism permits the load to be released so that the sliding block assembly can be inserted... 

A modification of the sliding-block technique was developed by Bowden and Yoffe (Ref 1), the app subjecting the expl to rapid shear while under a known load... 

Abrasive coasts are mostly composed of clayey deposits, poorly-cemented rocks, or limestones. The cliff heights range from 15 to 35 m. The abrasion rate is controlled by the composition of the coastal rocks and the cliff heights. The recession of the cliffs is also caused by the development of landslide and caving processes, especially under the conditions of strong storms. The length of individual sliding blocks reaches 500 m at a width of up to 15 m. Deep surf niches are formed in the lower parts of the cliffs. 

Among many shear-type tests the following are representative the mallet friction test, the sliding-block friction test, and the emery-paper friction test of the Explosives Research and Development Establishment, England, the U.S. Bureau of Mines pendulum friction test, and the Julius Peters friction test. Each of these can be used to test primary explosives, and some may be used also on secondary explosives. 

A sliding-block friction test apparatus is located at Picatinny Arsenal. 

Figure 24. Sliding-block friction apparatus (top) and block assembly and striker (bottom) [12].

Figure 25. Representation of the emery-paper friction apparatus [12] (a) sliding block (b) fixed block.

With the Julius Peters apparatus lead azide and mercury fulminate ranked in the same order (Table XV) as those obtained with grit or the sliding-block friction test. 

Table XIII. Sliding-Block Friction Sensitivities [16]...

Sliding block friction tester with 6 lb load. 

Fig 1 Sliding-block Friction Apparatus (top) and Block Assembly and Striker (bottom)... 

Using Newmark s sliding block approach, for a given harmonic ground acceleration time history and a known value of k, the sliding displaee-ment (F) can be calculated by double integrating the relative acceleration [k ks)9 the bloek as follows ... 

The sliding block is attached to the end of the cross-slide leadscrew and is guided in a bracket which is boited to the rear face of the saddle. 

Step G Topsoil depth distribution map is prepared by SSPT or other SPTs and the above patchwork structure is clarified. The measurement should be conducted by 2 10 meters grid or traverse method. Because shallow landslide size is generally within 10 50 meters, small shallow land slide blocks are overlooked if the grid size is too big. After the mapping, unstable zone is subdivided into some shallow landslide blocks/ patches. 

As a rational combination of Newmark s sliding block method (Newmark, 1965) and Janbu method (Janbu, 1957), extended Newmark and Janbu method (extended NJ method) has been used in earthquake induced slope failure (Deng etal.,2010). 

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