Yes / This study established a dynamic damage constitutive model for ultra-high performance concrete (UHPC) with nanofillers, based on a viscoelastic dynamic constitutive model and a damage evolution equation. Ten types of nanofillers, including particle, tube and flake nanofillers, were incorporated to modify UHPC. The split Hopkinson pressure bar was used to obtain the relationship between stress and strain of UHPC specimens at a strain rate of 200/s-800/s. The experimental results indicated that the dynamic compressive strength of UHPC with nanofillers at strain rates of approximately 200/s, 500/s, and 800/s can reach 172.8 MPa, 219.6 MPa, and 275.9 MPa, respectively, reflecting an increase of 85.2 %, 76.5 %, and 53.9 % compared with the blank UHPC. The established dynamic damage constitutive model considered the damage accumulation with strains under dynamic loading. The fitting coefficients of the dynamic damage constitutive model, when compared against experimental results, range from 0.8796 to 0.9963, showing a higher accuracy compared with traditional Zhu-Wang-Tang (ZWT) viscoelastic model, especially at a strain rate of approximately 200/s. / National Science Foundation of China (52178118 and 52308236), and the China Postdoctoral Science Foundation (2022M720648 and 2022M710973) / The full-text of this article will be released for public view at the end of the publisher embargo on 5 Jan 2025.

[pt] Esta dissertação apresenta um estudo numérico, utilizando o método dos elementos finitos, para simular o entupimento de rochas provocado pela injeção de água contendo partículas sólidas. Dentre os diferentes parâmetros que afetam o declínio de injetividade, quatro foram analisados, considerando-se a situação de fluxo unidimensional: fator de dano, concentração de partículas sólidas presentes no fluido de injeção, coeficiente de filtragem e taxa de injeção. Um estudo paramétrico ressaltando a influência destes fatores na perda de injetividade é também apresentado neste trabalho, concluindo-se que os resultados numéricos obtidos concordam satisfatoriamente com as observações experimentais disponíveis e soluções analíticas publicadas na literatura. O trabalho estuda também numericamente a simulação do entupimento dos poros da rocha considerando dois modelos de redução de permeabilidade e recupera valores do coeficiente de filtragem (Lambda ) e do fator de dano ( Beta ) através de análises inversa pelo método dos elementos finitos. / [en] This dissertation presents a numerical study, based on the finite element method, to simulate rock pore plugging caused by the injection of water containing solid particles in suspension. Amongst the parameters that affect rock injectivity decline, the following four were analyzed, considering undimensional flow: damage coefficient, solid particle concentration present in the injection fluid, filtration coefficient and injection rate. A parametric study standing out the influence of the these factors in the loss of injectivity is also presented in this work, concluding that the numerical results agree satisfactorily with the available experimental data and analytical solutions published in the literature. This work also numerically investigates the process of rock pore plugging considering two different permeability reduction models and recovers values of the filtration coefficient (Lambda ) and the damage factor ( Beta ) through inverse analyses carried outn by the finite element method.