THE ROLLER-GROUND DYNAMIC INTERACTION IN THE COMPACTION PROCESS THROUGH VIBRATIONS FOR ROAD CONSTRUCTION

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1 DOI: /rjti ROMANIAN JOURNAL THE ROLLER-GROUND DYNAMIC INTERACTION IN THE COMPACTION PROCESS THROUGH VIBRATIONS FOR ROAD CONSTRUCTION, dr.eng. Head of Chair of the Departent DMMC, Technical University of Moldova; Rezuat Terenul natural utilizat în uplutură, în terasaentul căilor de counicații, este caracterizat de urătorii factori: uiditate, porozitate, copactitate. Pentru anuite valori ale factorilor ce descriu starea păânturilor, se rearcă o anuită coportare a terenului sub acţiunea forţelor exterioare aplicate prin ijloace ecanice static sau dinaic. În această lucrare sunt prezentate rezultatele siulării nuerice a interacțiunii copactor-teren pe baza odelului reologic coplex și neliniar, propus de autor în rezultatul elaborării lucrării de cercetare, care ține seaa de caracteristicile reale ale terenului (elastice, disipative și plastice) și de cele ale utilajului de copactat (cu un singur rulou vibrator). Modelul a fost aronizat și acordat în conforitate cu rezultatele obținute la prelucrarea datelor experientale. Pentru siularea odelului a fost utilizat pachetul software specializat Matlab (Siulink, SiMechanics). Rezultatele obținute au evidențiat coportarea reală a utilajului și acțiunea sa asupra terenului supus copactării. Cuvinte cheie: Terasaente, copactor, vibrații, uiditate, odel reologic, dinaică. Abstract The natural soil used in filling the ebankent of the road counications is characterized by the following factors: huidity, porosity, toughness. For certain factor values that describe the soil state is distinguished a certain soil behavior under the influence of the external forces applied through static or dynaic echanical eans. In this study are presented the nueric siulation results of the soil-copactor interaction based on the coplex and nonlinear rheological odel proposed by the author in the result of the elaborated doctorate thesis, that follows the real soil characteristics (elastic, dissipative and plastic) on those of the copaction equipent (with a single vibrating roll). The odel was haronised and granted in accordance with the results obtained fro the processing of the experiental data. For the siulation odel was used the specialized software package Matlab (Siulink, SiMechanics). The obtained results revealed the real behavior of the equipent and its action on the copacted soil. Keywords: ebankent, copactor, vibrations, huidity, rheological odel, dynaics. Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No. 1

2 1. MODELING THE INTERACTION. Based on the experiental deterinations, resulted the functional relations of dependence between the essential paraeters that describe the copaction process of a ground when knowing the inforation about the copacting achinery (static or dynaic), the ground that needs copaction and the final copaction degree ust be realised at the end of the technological process. This connection relations allow the following the tande action-effect of an action during the technological process, respectively the prediction of the obtained effect in the conditions of a known action. By the effect of an action, we understand, in this research, both the effects of the actions suffered by the ground, and those produced on the technological copaction equipent. The elaboration of a atheatical odel that siulates the behavior of a real (physical) syste can be obtained by following the steps given in Figure 1. Figure 1. The steps of the elaboration of a atheatical odel of the echanical syste [1] Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No.

3 . DYNAMIC MODEL FOR INTERACTION STUDY OF THE ROLLER- GROUND COMPACTION The siplest dynaic odel for odelling the interaction between the roller and the ground, using a single vibrator roll, is presented in Figure. The odel has a single liberty degree objectified in the displaceent of the vibratory roll on a vertical direction [; 3]. g 1 g w x r F 0 F s Interacţiune rulou-teren F s Teren k c x s Figure.. The dynaic odel with a single liberty degree for the interaction study roller-ground for a single vibrator roll. The oveent equation of the dynaic syste presented in Figure is: r x r ( r ) g 0rw cosw t Fs (1) where: r is the ass of the vibrator roll; the ass of the achinery chassis; 0 r the static oent of the eccentric pieces; w - the pulsation of the disruptive force; x r the vertical displaceent of the chassis; F s the contact force between the roller and the ground. The force expression between the roller and the ground can also be written like: Fs kxs cx s () where k represents the rigidity coefficient of the ground; c the coefficient of the ground aortization. The relation () is valid for x s 0, but for x s <0 the force value F s is zero. Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No. 3

4 For the odel oveent analysis were considered the following identification data of the vibrator roll and ground: = 1000 kg; r = 3000 kg; 0 r =5...0 kg; ω = /5 Hz; k =(1...4)10 5 kn/; c = 4.10 Ns/; in the figures The influence of the rigidity variation of the ground layer on the dynaic paraeters The ost eloquent behavior of the natural ground or of the ground stabilized with ineral products (lie, bituen, concrete) or organic (enzyes, polienzyes) is described by two coposed odels: the Voght-Kelvin odel and the Maxwell odel. In this research study will be elaborated odels with a discreet variable rigidity. In this oent, for each pass of the vibrator roll on the sae layer of ground will be realised a certain rigidity, so after n passes will be reached n values for the rigidities k 1,k... k n. The dynaic answer will be given through the following paraeters: the aplitude of the iediate displaceent of the vibrations, noted with A ( Ω,ζ). This way for each odel will be noticed the growing influence of the rigidity on the paraetric values. Finally, is presented the coplete study for the sae vibrator roll and the two rheological odels The Voigt Kelvin (E/V) Model For the dynaic odel are considered the following initial data: Kg ; c 4 10 Ns ; 0r 0 Kg w k k w ,, 3, 4 10 N ; k c ; k The aplitude has the for: A VK r 0, 1 4 (3) Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No. 4

5 Figure. 3. The rheological Voight+Kelvin odel. Figure. 4. The aplitude variation with the pulsation and rigidity. Figure. 5. The transitted speed variation in relation with the pulsation. The forwarded force in relation with the relative pulsation Ω= ω = ω p k aortisation ζ is Q VK r , k 1 4 and (4) Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No. 5

6 Figure. 6. The transissibility variation in relation with the pulsation. Is ascertained that the forwarded force depends on the static oent of the vibrator, the roller s ass, rigidity of the ground layer after copaction, the relative pulsation and aortisation fro where is ascertained that the transissibility depends only on the rigidity and aortisation of the ground. De dynaic transissibility is given by the forula: T VK,.1.. The Maxwell (E -V) Model The rheological odel given in Figure 7 is coposed fro two siple rheological eleents, k and c, in series. In this case, the variable rigidity attracts the odification of the relative pulsation and of the fractions for the critical aortisation. The aplitude has the following for: (5) A M r 0, (6) Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No. 6

7 Figure. 7. The rheological Maxwel odel. The forwarded force to the ground is given by the relation: Q M 0 r 0, k 4 1 and directly depends by the relative pulsation and rigidity that leads to the curves represented in Figure 9, with the specification that the aortisation factor is deteriner. So, if c 0 and if ζ 0, than the transissibility is cancelled. (7) Figure. 8. The aplitude variation with the pulsation. Figure. 9. The force variation with the pulsation. The force transissibility is given by the forula: M T, 4 1 (8) Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No. 7

8 Figure. 10. The transissibility variation with the pulsation. Based on the diagras fro Figures 8, 9 and 10 is ascertained that the forwarded effect of the force is uch reduced at high pulsations of the vibration. For this reason, the poor cohesive, sandy grounds, with plenty of water in the structural content are difficult or alost ipossible to copact. For this are used cheical or organic stabilizers that can odify the rheological behavior. In conclusion, is noticed that the Vogt-Kelvin odel is the one that ensures a better transissibility for the post resonance doain and leads to expected results of the copaction degree. 3. CONCLUSIONS Models and systes of analysis can be realised inforatively and nuerical, with the coherent integration for the evolution of the essential paraeters that characterize the technological process of dynaic copaction through vibration. Underlining the ground answer under the action of the dynaic force produced by the vibrator roll, together with its coponents in rheological ters of the coposite aterials with a coplex elastic, dissipative and plastic type behavior, helps understand the specific phenoenology of the equipent-ground interaction and facilitates the technological optiization process through the iproveent of the functional perforances of the technological equipent specific for the dynaic copaction. The final purpose of this optiization is to obtain higher values of the copaction degree. Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No. 8

9 This way the analysis of the dynaic copaction process through vibration is necessary by using the cobined ethods for the technological equipent, with those advanced towards the ground rheology (with the optiization of the paraeters specific for the typology of the working zone) and with eleents specific for the way of working (ipleentation of the technological structure of approach of the dynaic copaction process). It results that it is required a pre-evaluation of the ground answer and of the request status iposed by the equipent, followed by the coplex siulation of the cuulative effect produced by the successive passes and the in depth evaluation of the copaction degree on the entire zone of interest, with the real dynaic siulation of the dynaic actions and with the sweep on the entire onitorized zone. BIBLIOGRAPHY [1]. GANCIU T.: Identificarea sisteelor, Editura Nord-Est, Iași, Roania,1995; []. THURNER, H.F., SANDSTRÖM, A.: Continuous Copaction Control, CCC, European Workshop Copaction of Soils and Granular Materials, Paris, May 19 th, pp , 000; [3]. WHITE, D., THOMPSON, M.: Relationships Between In Situ and Roller-Integrated Copaction Measureents for Granular Soils, Journal of Geotechnical and Geoenvironental Engineering, ASCE, Vol. 134, No. 1, pp , 008; Article No.1, Roanian Journal of Transport Infrastructure, Vol.5, 016, No. 9