A dynamic large-deformation particle finite element method for geotechnical applications based on Abaqus

In this paper,the application of Abaqus-based particle finite element method(PFEM)is extended from static to dynamic large deformation.The PFEM is based on periodic mesh regeneration with Delaunay triangulation to avoid mesh distortion.Additional mesh smoothing and boundary node smoothing techniques are incorporated to improve the mesh quality and solution accuracy.The field variables are mapped from the old to the new mesh using the closest point projection method to minimize the mapping error.The procedures of the proposed Abaqus-based dynamic PFEM(Abaqus-DPFEM)analysis and its implementation in Abaqus are detailed.The accuracy and robustness of the proposed approach are examined via four illustrative numerical examples.The numerical results show a satisfactory agreement with published results and further confirm the applicability of the Abaqus-DPFEM to solving dynamic large-deformation problems in geotechnical engineering.

The safety distance of a tunnel under-traversing a slope body with a landslide-prone zone

At present,substantial scientific research achievements have been made in the research on landslide occurrence,movement mechanism,mitigation measures,and structural stability during tunnel excavation.However,the interaction mechanism of a tunnel under-traversing a slope body with potential landslides is still not well understood.Based on the field data provided by previous investigations in the study area,six sets of 1:100 laboratory experiment model tests were conducted to study the stability of the landslide-prone zone of the slope body with an under-traversing tunnel.The selected distances between the tunnel and the sliding surface are 1.5,3,and 5 times of the tunnel diameter,respectively.The experiment results show the interaction between the landslide-prone zone and the tunnel,elucidating the effect of potential landslides during the tunnel excavation process and the reaction of the landslide slip on the tunnel structure.Several conclusions are obtained:①During the process of tunnel excavation,the vertical displacement of the tunnel vault decreases with the increase of the buried depth.②The vertical displacement of the sliding surface increases with the increase of the buried depth of the tunnel.The horizontal displacement of sliding surface decreases with the increase of the buried depth.③After the occurrence of a rainfall-induced landslide,the vertical displacement of the tunnel vault in the 1.5-diameter-distance case is 57.29%greater than that in the 3.0-dismeter-distance case.④For a two-cave tunnel,it is suggested that the cave farther from the landslide toe should be firstly excavated since it may generate less structural deformation.

Full sexual maturity-cycle exposure to environmentally relevant concentrations of 17β-estradiol decreases reproductive capacity of zebrafish

17β-Estradiol(E2)has been widely detected in natural water and treatment with E2 induces potential endocrine disrupting effects in fish.However,effects on fish fecundity and steroid system after treatment with environmentally relevant concentrations of E2 for the full sexual maturation cycle remain unclear.In this study,zebrafish were treatment with 0,10 or100 ng/L E2 from embryo to adult stage,and effects on gonadal development and differentiation,steroid hormone levels,transcription of genes associated with the hypothalamic-pituitary-gonadal-liver(HPG)axis in adults and fertilization rate of offspring were assessed.The results showed that treatment with E2 lead to increased number of feminization in zebrafish.In females,E2 decreased cumulative amount of spawning and inhibited the maturation of oocyte.In males,E2 inhibited the maturation and motility of sperm,as well as decreased the movement speed of sperm.These adverse effects on sperm might be responsible for the reduced fertilization observed in offspring.In addition,treatment with E2 changed the levels of steroid hormones in zebrafish gonad and altered the transcriptional levels of genes associated with HPG axis,which is responsible for the regulation of germ cells maturation and gonadal development in zebrafish.Overall,these results suggested that treatment with environmentally relevant concentrations of E2 for the full sexual maturity cycle resulted in adverse effects on reproduction in zebrafish.