Amirkabir University of Technology Amirkabir Journal of Civil Engineering 2588-297X 53 4 2021 06 22 Effective Factors on the Results of Geotechnical Penetration Tests by Using Manual Dynamic Penetrometer (MDP) in Sandy Soil Effective Factors on the Results of Geotechnical Penetration Tests by Using Manual Dynamic Penetrometer (MDP) in Sandy Soil 1295 1306 3796 10.22060/ceej.2020.16856.6375 FA Mahdi Sardar Civil Engineering Department, Ferdowsi University of Mashhad Ehsan Seyedi Hosseininia Civil Eng. Department, Faculty of engineering, Ferdowsi University of Mashhad Journal Article 2019 07 31 Penetration tests in geotechnical engineering are field tests in order to estimate some soil parameters such as soil density, CBR (California Bearing Ratio) and internal friction angle. The advantages of these tests to other field tests are the easiness and rapidity in the application. Although the accuracy of these tests might be in question, the tests can be calibrated by other tests with accepted accuracy. In this paper, a penetration test, called Manual Dynamic Penetrometer (MDP), is introduced, which is designed and constructed at Ferdowsi University of Mashhad (FUM). The principles of the applicability of MDP are similar to other existing penetration tests (such as DCP introduced in ASTM D6591); however, the energy applied to the soil is much higher which facilitates to have more penetrated depth compared to other existing probes. In this apparatus, the probe is a solid 60-degree cone with a diameter of 18mm and the string rod diameter is 16 mm. The cone and string rod are impacted by a hammer with a mass of 10 kilograms which is manually raised and then it falls from a height of 600 mm.  In this paper, MDP was applied within Firuzkuh-161 sandy soil with different soil relative densities (Dr = 55, 80, 100%). In this research, different factors influencing the penetration are investigated by using MDP. These factors are the geometry of the cone (cone apex=30^o, 60^o, and 90^o), the cone diameter (18, 30, 40 mm), and the hammer mass (5, 8, 10 kg). The penetration results are presented in terms of penetration index (DPI) which is described as penetrated depth per each impact. By comparing the results, it is found out that cone apex has no influence on the penetration, but the cone diameter changes the rate of penetration. Furthermore, it is seen that there is a linear relationship between applied energy and the average DPI such as what is already used in SPT correlations. By considering the similitude of MDP test and pile driving, it is shown that the results of penetration tests can be used to estimate the internal friction angle of sandy soils. Penetration tests in geotechnical engineering are field tests in order to estimate some soil parameters such as soil density, CBR (California Bearing Ratio) and internal friction angle. The advantages of these tests to other field tests are the easiness and rapidity in the application. Although the accuracy of these tests might be in question, the tests can be calibrated by other tests with accepted accuracy. In this paper, a penetration test, called Manual Dynamic Penetrometer (MDP), is introduced, which is designed and constructed at Ferdowsi University of Mashhad (FUM). The principles of the applicability of MDP are similar to other existing penetration tests (such as DCP introduced in ASTM D6591); however, the energy applied to the soil is much higher which facilitates to have more penetrated depth compared to other existing probes. In this apparatus, the probe is a solid 60-degree cone with a diameter of 18mm and the string rod diameter is 16 mm. The cone and string rod are impacted by a hammer with a mass of 10 kilograms which is manually raised and then it falls from a height of 600 mm.  In this paper, MDP was applied within Firuzkuh-161 sandy soil with different soil relative densities (Dr = 55, 80, 100%). In this research, different factors influencing the penetration are investigated by using MDP. These factors are the geometry of the cone (cone apex=30^o, 60^o, and 90^o), the cone diameter (18, 30, 40 mm), and the hammer mass (5, 8, 10 kg). The penetration results are presented in terms of penetration index (DPI) which is described as penetrated depth per each impact. By comparing the results, it is found out that cone apex has no influence on the penetration, but the cone diameter changes the rate of penetration. Furthermore, it is seen that there is a linear relationship between applied energy and the average DPI such as what is already used in SPT correlations. By considering the similitude of MDP test and pile driving, it is shown that the results of penetration tests can be used to estimate the internal friction angle of sandy soils. https://ceej.aut.ac.ir/article_3796_41c542dfe6e4fc3deb251d64cf6ed2e4.pdf