# Experimental and Numerical Study in Dynamic Compaction of Weakly-Cohesive Soils
## 6 Conclusions  
The presented analytical simulation models enable the evaluation of the vertical drum motion of a vibratory roller on homogeneous terrain, considering the drum response at changing compaction degrees. Using a roller ABG-DD16 and terrain parameters, in this paper, the results of the modeling and simulation highlighted that the characteristic aspects of the weakly cohesive soil compaction exhibited uniform characteristics. From the analysis of the experimental data, it is found that after 12 successive passes of the roller on the same layer, the settlement value tends asymptotically towards a characteristic limit value of the respective layer. The spectral analysis performed on the acquired signals corresponding to the movement of the compactor roller allows the provision of useful data for the design of a special system for determining the degree of compaction in real time with direct implications on the optimization of the technological and operational parameters of the machine. As can be seen from Figures 10-12, our simulation results are in good agreement with the experimental results. The main achievements of the research are as follows:  
1. The comparison of obtained results involving the evolution of the main specific parameters that define compaction efficiency (as a measure of compaction degree improvement) shows that the presented models lead to results that are close to reality and comparable with the measured data. 2. The results of simulation with a constant drum contact width (based on the generalized Kelvin-Voigt model) offer a global overview of the compaction process efficiency, useful for the prediction of study cases (without providing exact results, only approximately). The continuous change of the contact width of the drum, depending on the degree of compaction achieved after several passes, and the shape of the resulting curves agrees with the data measured in situ. 3. Only the working mode with continuous contact was considered in this paper, but with additional boundary conditions, the jumping working mode of the vibratory roller can also be simulated with the presented models (for future research directions). 4. Analytical models simulating the behavior of the soil in the compaction process must consider the geometric nonlinearity introduced by the variable contact width of the drum, such as the nonlinearity of the plastic deformations in the loading phase. 5. The models are recommended for studying the influence of constitutive parameters, as they allow investigations in broad limits without numerical difficulties and with short calculation times. 6. Further studies are needed to optimize the equipment for increasing its compaction efficiency. The results suggest that a vibratory roller with a larger eccentric moment, and thus a higher centrifugal force, would have resulted in more efficient compaction. This paper concentrates on the modeling and simulation of soil compaction with uniform properties, and the objective of future research will be focused on the compaction of weakly cohesive soil exhibiting non-uniform characteristics (as the soils are in fact). For this type of soil, achieving consistent compaction becomes more difficult because it requires a thorough understanding of the soil's specific characteristics to select the appropriate compaction equipment, maintain optimal moisture content, control layer thickness effectively, etc. Some of these aspects will be approached, and the model proposed in this paper will be improved by incorporating additional elements that model in depth the strongly non-linear characteristics of the types of soil analyzed. It is obvious that this refinement of the computational model requires a series of initial pre-evaluations of the values of the reference parameters, and this last aspect will constitute the central objective of the next study by the group of authors. Conceptualization, C.N.D. and A.B. ; methodology, A.B. and C.N.D. ; software, S.M.N. and C.N.D. ; validation, C.N.D. ; formal analysis, A.B. and S.M.N.