Uporaba Perthovega penetrometra za peske (PSP) za določitev inženirskih parametrov peskov

Determining the in-situ engineering parameters of sandy soils has always been a challenge for geotechnical engineers, resulting in several methods having been developed so far. The Perth Sand Penetrometer (PSP) test is one of the most versatile of these methods. It is a considerably faster and cheaper tool than boring equipment, especially when the depth of the exploration is moderate. In the present research, a methodology for the use of a PSP device to evaluate the engineering parameters of sandy soils in laboratory conditions is discussed and the repeatability of the test results is studied. First of all, the tests were performed on typical Tehran young alluvial deposits (poorly graded sandy soil, SP) consistently prepared to 5 densities using the sand raining or pluviation technique. Next, the normal and logNormal distributions of the test data using the Kolmogorov-Smirnov normality test were examined. After that, based on the obtained results, the relationship types between the dynamic point resistance index (qd) and other parameters, such as the relative density (Dr), the modulus of elasticity (E), the shear modulus (G) and the friction angle of the soil, were determined. The results show that the obtained relationships were semi-logarithmic and logarithmic, and most of the obtained experimental formulas had a high coefficient of determination (>90%). To evaluate the accuracy of the results, 95% confidence and prediction bands were also used and the results show that all the obtained experimental relationships were appropriate. Finally, the repeatability of the test results was evaluated by calculating the coefficient of variations, which was less than 30% for all the tests. Določanje in-situ inženirskih parametrov peščenih zemljin je bil vedno izziv za geotehnične inženirje, zaradi česar je bilo do sedaj razvitih več metod. Preizkus s Perthovim penetrometrom za peske (PSP) je ena od najbolj vsestranskih metod. Je bistveno hitrejše in cenejše orodje kot vrtalna oprema, še posebej, če je globina raziskovanja zmerna. V prikazani raziskavi je obravnavana metodologija za uporabo naprave PSP za ovrednotenje inženirskih parametrov peščenih zemljin v laboratorijskih pogojih in preučevana ponovljivosti rezultatov preizkusa. Najprej so bili izvedeni preizkusi na tipičnih teheranskih mladih naplavinah (slabo granulirana peščena zemljina, SP), na vzorcih petih različnih gostot, navlaženih s pršenjem ali zalivanjem. Dalje so bile proučene običajne in logNormal porazdelitve podatkov o preizkusih z uporabo Kolmogorov-Smirnov testa normalnosti porazdelitve. Nato pa so bile, na podlagi dobljenih rezultatov, določene vrste razmerij med dinamičnim točkovnim indeksom odpora qd in drugimi parametri, kot so relativna gostota (Dr), modul elastičnosti (E), strižni modul (G) in trenjski kot zemljine. Rezultati kažejo, da so dobljeni odnosi pol-logaritmični in logaritmični, večina dobljenih eksperimentalnih enačb ima visok koeficient določanja (>90%). Za oceno natančnosti rezultatov je bil uporabljen interval zaupanja meritev pri 95% zanesljivosti. Rezultati kažejo, da so bili vsi dobljeni eksperimentalni odnosi ustrezni. Nazadnje je bila ponovljivost rezultatov testov ocenjena z izračunom koeficienta variacije, ki je bil za vse teste manjši od 30%.