Çevik, Mustafa Efekan
The Standard Penetration Test (SPT) is the most widely used in-situ dynamic penetration test to identify the geotechnical properties of mostly cohesionless soils for over 100 years. Although ASTM defines the procedure of the SPT, the test itself has special variabilities due to many uncertainties. It can be seen that, with different equipment and operator, one can obtain significantly different SPT-N values that belong to the same soil profile. To minimize this difference, some correction factors are used. The energy efficiency of the SPT hammer has been investigated since the 1970s. Two different energy measurement methods are used to calculate the energy transfer ratio: the force square (F2) method and the Force-Velocity (FV) method. The F² method was instated to ASTM D4633 in 1986 and withdrawn in 1995. ASTM D4633 was reinstated in 2005 using the FV method and used ever since. Nowadays, the only energy measurement method is the FV method; however, one of the most widely used energy correction publication, NCEER-97, is prepared on the basis of findings with the F2 method. In the present study, the effect of hammer-rod alignment on the hammer energy ratio has been studied through a set of in-situ tests, where SPT hammer efficiency is monitored. Additionally, available data from literature is compiled. On the basis of these, it is concluded that the hammer-rod alignment has an essential effect on the delivery of the energy ratio. With the increasing eccentricity of hammer anvil contact, energy efficiency decreases. Additionally, energy efficiency decreases with decreasing hammer rod length. This decrease is observed to be less than what is recommended by NCEER-97. As the concluding remark, a series of recommendations are listed to assess the energy ratio values for safety and automatic hammers along with the effects of SPT rod shorter than 10 meters.


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Pehlivan, Alper; Yılmaz, Mustafa Tolga; Department of Engineering Sciences (2019)
Variability in the results of standard penetration tests (SPT) due to nonuniformity of particle size distribution in soil layers is a known issue in geotechnical applications. Such phenomenon may result in artificial increase in penetration resistance in silts, clays and sands due to encountering large particles. An analysis of SPT variability in such cases can be conducted by dividing the total penetration distance into two smaller segments. In this study, the difference between number of blow counts for t...
The Characterization of a Tar Sand Sample Using Differential Scanning Calorimeters
Senguler, I.; Kök, Mustafa Verşan (2013-01-01)
In this study, non-isothermal kinetics and a thermal analysis tar sand sample is studied by differential scanning calorimeter and pressurized differential scanning calorimeter. Differential scanning calorimeter and pressurized differential scanning calorimeter curves revealed two reaction regions in the temperature range of 20-600 degrees C. Effect of pressure was also studied in order to see the thermal behavior of a tar sand sample under different elevated pressures. Two different kinetic methods (ASTM an...
A probabilistic model for CPT-based soil classification
Çetin, Kemal Önder (2003-07-09)
Due to lack of soil sampling during a conventional cone penetration testing, it is necessary to classify soils based on recorded tip and sleeve friction values. Currently available semi-empirical methods of Robertson and Wride (1997) and Olsen and Mitchell (1995) exhibit a significant variability in the estimation of soil type based on cone penetration test (CPT) data. Thus within the confines of this paper it is attempted to present a new probabilistic CPT-based soil classification methodology which addres...
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The effects of fourth generation on the total branching ratio and the lepton polarization in Lambda(b)->Lambda l(+) l(-) decay
Bashiry, Vali; Azizi, Kazem (2007-07-01)
This study investigates the influence of the fourth generation quarks on the total branching ratio and the single lepton polarizations in Lambda(b) -> Lambda l(+)l(-) decay. Taking vertical bar Vt ' sVt ' b vertical bar similar to {0.01-0.03} with phase just below 90 degrees, which is consistent with the b -> sl(+)l(-) rate and the B-s mixing parameter Delta(mBs), we obtain that the total branching ratio and the single lepton (mu,tau) polarizations are quite sensitive to the existence of fourth generation. ...
Citation Formats
M. E. Çevik, “THE EFFECTS OF HAMMER-ROD ALIGNMENT AND ROD LENGTH ON SPT HAMMER EFFICIENCY,” M.S. - Master of Science, Middle East Technical University, 2021.