Electronic Hammer for Nondestructive Determination of Compaction Characteristics of Fine – Grained Soils

چکیده مقاله

Obtaining physical and mechanical parameters of soil are mostly obtained in laboratories or by field tests. The main goal of this research is to determine compaction characteristics of fine-grained soils (clayey soils or Kaolinite) using an invented electronic hammer without the necessity of sampling and its complexity. To verify the accuracy of the invented device, first, using the modified Proctor compaction test introduced in AASHTO standard, is prepared compacted soil with different ratios. Induced shear waves increase resistance and voltage of strain gauge and force sensor. These values are transmitted to the AVR microcontroller using an ADC and finally, the soil strength is computed and displayed on the LCD. Comparing the results of the electronic hammer with direct shear test device leads to obtaining numerous correlation relations. Several soil samples with different compaction percentages and specific weights are evaluated and just with an impact of the hammer on the surface and using the correlation relations, compaction percentage or specific weight is estimated. The results show values less than 2 hammer reading are equivalent to compaction percentage less than 75% and more than 3 hammer reading values are equivalent to compaction percentage more than 90%.