Undisturbed penetration

ASTM D 217. Standard test temperature is 25°C (77°F). The higher the penetration number, the softer the grease. Undisturbed penetration is the penetration of a... 

To gain quantitative information on the profile characteristics, the profile shape must be evaluated mathematically. The parameter Dt (D, diffusion constant t, exposure time) that describes the depth of the diffusion front that penetrated into the sample was determined by fitting the data with an error function (erf). The resulting curve describes the result of an undisturbed diffusion process. If the exposure time t is known, e.g. by radiocarbon dating, the diffusion constant D, a material constant, can be derived from this data. 

The undisturbed organic and the inorganic matrix in a bone form a very stable network which is the reason for the extreme stability of bone. So a mineralized collagen can survive into the archaeological record under certain circumstances and an intact collagen phase can prevent fluorine from penetrating into the sample (Fig. 9). A well-preserved bone may thus show a less-developed profile than a far degraded sample of the same age. 

In undisturbed systems pollutants reach the base flow zone and do not penetrate into deeper (below sea level) stagnant parts of the system. Thus the deeper stagnant parts below through-flow systems may serve as a strategic reserve of clean water. Lowering of the water table may ruin this reserve because it lets pollutants reach the deeper parts of the system. 

The usual method for obtaining samples at significant depths below the surface is to push or drive a pipe or tube into undisturbed soil at the bottom of a drill hole. Of course, this process disturbs the soil, particularly when the pipe is heavy walled. Many different kinds and sizes of samplers are used, and the most common is shown in Figure 1.1. This sampler is commonly called a split spoon. When used with the dimensions shown, and hammered into the soil by a free falling, 140 pound weight, dropping 30 inches, this is the Standard Penetration Test (see ASTM Standard D.1586,... 

Farther away from the surface the fluid velocities, though less than the velocity of the undisturbed fluid, may be fairly large, and flow in this part of the boundary layer may become turbulent. Between the zone of fully developed turbulence and the region of laminar flow is a transition, or buffer, layer of intermediate character. Thus a turbulent boundary layer is considered to consist of three zones the viscous sublayer, the buffer layer, and the turbulent zone. The existence of a completely viscous sublayer is questioned by some, since mass transfer studies suggest that some eddies penetrate all the way through the boundary layer and reach the wall. 

Note that in Equation 5.15, unit weight is assumed to be equal to unit weight of pile. Because Nq is dependent on 0, a sample has to be obtained and tested for 0. For sand and granular soils, it is difficult to obtain their undisturbed samples. Because of this, an in situ test is usually performed to obtain 0. Two in situ test methods normally used are the standard penetration test (SPT) and cone penetration test (CPT). Some of these correlations have been presented earlier in this chapter. Figure 5.8 shows a plot of the bearing capacity factor, Nq. 

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