## 5 Conclusions
Following the response values in the family of curves, we can determine the parameters of the Voigt-Kelvin model after each passage, namely \(k_{i}\) and \(c_{i}\) or \(k_{i}\) and \(\zeta_{i}\). * The parameters \(k\), \(c\) and \(Q_{0,I}^{\text{res}}\) for the first category of soils with constant damping, based on the response curves plotted experimentally in situ (Figure 1) in the compaction with a vibrating roller, can be calculated as follows: \(k_{i}^{I}=m\omega_{n,i}^{2}\); \(i=1.5\) for each value of i = 1.5; \(c=\frac{m_{0}\
u_{n,i}}{A_{n,i}^{I}}\) for each value of \(i=1.5\); \(\left(Q_{0,I}^{\text{res}}\right)_{i}=\frac{m_{0}\
u_{n,i}}{c}\sqrt{k_{i}^{2} +c^{2}\omega_{n,i}^{2}}\) for each value of \(i=1.5\). * The parameters \(k\), \(\zeta\) and \(Q_{0,I}^{\text{res}}\) for the second category of soils with different damping from one passage to the next one, based on the experimentally plotted response curves (Figure 3), can be calculated as follows: \(k_{i}^{II}=m\omega_{n,i}^{2}\); \(i=1.5\) for each value of \(i=1.5\); \(\zeta_{i}=\frac{m_{0}\
u}{m}\frac{1}{2A_{n,i}^{II}}\) for each value of \(i=1.5\); \(i=1.5\); \(\left(Q_{0,II}^{\text{res}}\right)_{i}=\frac{1}{2}m_{0}\
u\omega_{n,i}^{2} \sqrt{4+\frac{1}{\zeta_{i}^{2}}}\) for each value of \(i=1.5\). Given the abovementioned aspects, we can draw the conclusion that, depending on the family of response curves, the envelope curve can be shown as the geometric place of the amplitude peaks at resonance. Therefore, according to the nature of the soil, we can distinguish between two cases in which the envelope of the resonance points is the straight line indicating the ascending direction of the amplitude with its own frequency, and, on the other hand, the envelope, in the form of a curve, indicating the descending direction of the amplitude with its own frequency. Hence, the earth (soil) to be compacted can be classified as a defined rheological system and it can be \"calibrated\" based on the plotting of the envelope curves in the system \(A-\omega\) with the parameters \(k\), \(c\) or \(\zeta\), according to one of the two described situations. In this context, the conceptual basis for two categories of technical specifications is constituted, approved by the Romanian Ministry of Regional Developments and Public Administration regarding the assessment of the capability level of dynamic compaction equipment for road construction works. On the other hand, the Research Institute for Construction Equipment and Technology--ICECON, from Bucharest, Romania, developed, in 2019, operational procedures for the optimization of the compaction process with vibratory rollers depending on the soil category on which the road structures are realised. In essence, it is emphasized that the presented results are capitalized for engineering practical purposes. A research program is currently being carried out with the aim of creating an intelligent system for the detecting, logging and processing of technological vibration signals, in real time, so that the response curves can be plotted using a specialized software. They have to ensure the compaction degree, the dynamic rigidity and the dynamic modulus of the compacted soil in correlation with the laboratory tests, so that the quality of the compaction process is able to be verified in real time. This research received no external funding. The author declares no conflict of interest.