The data from study C were originally described by Morgano and Liang and were made available for review by Morgano , personal communication. These observations suggest that the interface friction component of the total penetration resistance during an SPT may decrease with increasing D50 , all other factors held constant. The theoretical correlation procedure described in the previous section can be adapted to that end. In contrast, numerical studies are well suited for parametric studies and provide complete knowledge of the factors affecting the results at all times. They noted that the soil particle size did not significantly affect the peak normalized cone tip pressure Q , provided the ratio of the cone diameter to the mean grain size was greater than Real hammers, anvils and rod strings are considerably different than the idealized case, and the error inherent in this correction is unknown. The instrumentation is expensive and somewhat delicate, and large amounts of data must be collected and stored during each hammer blow.

Research paper about computer. Finally, he reviewed rod energy ratio data from the literature and, using estimated velocity energy ratios based on the hammer release method, calculated energy transfer ratios. A leading arch would effectively transfer some of the load required to cause a bearing failure of the soil beneath the plug to the platens, thus reducing the internal friction required to initiate a fully or partially plugged penetration mode. Energy corrected blow counts are denoted N The underlying cause of plugging for the remaining simulations is clearly related to the ratio of the platen spacing to the mean particle size. Constant platen dimensions were maintained in order to simplify interpretation of the resulting data, as any variations of penetration energy may then be attributed to either the single platen effects described in the previous section or to platen spacing effects. Variation of LPT blow counts with grain size is assumed to be negligible.

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nancy stolle dissertation

Energy, kJ ft-lb SPT It was observed that the mean shear zone thickness decreased from roughly 6 to 2 times the mean particle size as the particle size was increased Table 7.

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The sampler is driven by repeatedly dropping a Based on the available data, it can only be concluded that the effect of rod type on ETR, if any exists, appears to be minor. The latter range has been included in Figure 4. Also shown are profiles of the cumulative penetration energy, calculated by integrating Figure 7.

Nancy stolle dissertation

The use of short rod corrections CR during calibration chamber studies leads to a uniform reduction of all measured blow counts as per the equation: The data from studies A and B are shown in Figures 4.

The plug length is seen to vary with platen spacing in Figure 7. The T-gravel data cover a wide range of CD values and nzncy provide insight into the cause of the observed increase of variability in gravels. Essay spm speech about school bully.

The measured energy transfer ratio would then be equal to: Perhaps the most relevant observation was made by Kokusho and Yoshida who, in their description of the CRIEPI study, noted that blow counts recorded using rods of 3 and 6 m length were not significantly different. They noted that the average ratio of N values for blow counts measured at the same depth was 1.

Nancy stolle dissertation

In this chapter, Nancu data from the literature are reviewed in greater detail and compiled into a single data set. To apply for the Dissertation Awards, please attach the following items in an email to by Dec. The trend-lines in Figure 8. Normalization of dual platen energies using the corresponding Emax values Figure 7. Figliola and Beasley, The plots illustrate the expected decrease in the number of particle-particle and particle-platen contacts with increasing particle size, and an associated increase in contact force magnitude.


It is postulated that the decreased slope of the CD SPT versus D50 relationship observed in gravels is due to similar processes in real soils, and that 2.

The efficiency with which the hammer kinetic energy is transferred to the drill rods can thus be quantified by the energy transfer ratio ETRdefined as: The British and Unified schemes identify gravel particles as those with diameters greater than 2. The 7propagation of uncertainty from stolel measurements to the final energy corrected blow count is investigated in Chapter stlole and the proposed energy correction procedure is shown to be superior to traditional procedures.

Chapter 3 describes a proposed alternate approach to energy correction of SPT blow counts dissertattion on the hammer kinetic energy. The 79 data points recorded using rod lengths less than 7. These very disssrtation loads are distributed below the leading edges along numerous chains of particle contacts.

Simple, closed-form expressions for the areas under Normal and LogNormal distribution curves are not available, but P x is easily determined using descriptive tables or special functions incorporated into stplle software. Trends in plot b have been forced dissertaation point CD 0. Energy corrected blow counts are denoted N Velocity data are particularly susceptible to errors due to high peak accelerations and the cumulative effect of minor baseline errors during integration of the acceleration history.

RostockFormer East Germany. This is not uncommon when uncertainty is primarily due to bias error, as bias errors are notoriously difficult to quantify. The use of the FV method during this study will have allowed the measurement of energy transferred during secondary impacts, which is an improvement over the F2 method.

nancy stolle dissertation

The ETRm values were calculated using d values determined from the blows per 25 mm data.