This paper investigates the impact dynamics of pile-soil interactions, focusing on the mechanisms of kinetic energy dissipation within these systems during vehicular impacts. The study aimed to quantitatively evaluate the force-displacement and energy-displacement responses of piles embedded in crushed limestone material through dynamic bogie testing. A three-dimensional, large-deformation, nonlinear finite element model was developed to enhance the analysis. The computational model integrated a damage-based, elastoviscoplastic soil model with an elastoplastic steel pile model, incorporating strain rate effects. A continuum, damage-based element-erosion algorithm is also employed to accurately simulate large soil deformations, representing a significant advancement in simulation capabilities. The proposed model was validated against physical impact test data, demonstrating a strong correlation with measured force-displacement and energy-displacement results. This model was subsequently utilized to investigate the effects of impact velocity and soil strength on the energy dissipation capacity of pile-soil systems during lateral vehicular impacts. Additionally, this study critically examined the limitations of conventional simulation methods, such as the Updated Lagrangian Finite Element Method (UL-FEM), in capturing the dynamic pile-soil interactions and large soil deformations involved in laterally-impacted pile-soil systems. The research provided fundamental insights into the mechanics of dynamic soil-structure interactions under impact loading, contributing significantly to the geotechnical design and analysis of soil-embedded vehicle barrier systems.

Layered structure in sand deposits is prevalent not only in reclaimed soils but also in natural alluvial soils. Liquefaction tests by a self-developed impact load system were carried out to investigate the excess pore water pressure (EPWP) generation and related liquefaction mechanism in layered sands, considering cases of uniform, two layered and interlayered sand columns respectively. Results show that the EPWP of saturated sands under impact loading presents two phases: transient response and steady-state response. For sands without interlayer, lower-permeability soil layer determines the rate of EPWP dissipation and lower permeability can result in smaller value of steady pore pressure but longer duration of that. For interlayered sands, presence of less permeable interlayer will prolong the total duration of pore pressure dissipation, and there is a significant high pore pressure sustained period during the dissipation stage of pore pressure, which is unfavorable for the liquefaction. Also, the presence of a less permeable interlayer within the sand deposit can lead to formation of water film underneath the interlayer. Besides, theoretical analysis of EPWP and water film under the same conditions are made, and it shows a good consistency between theoretical and test results, which verifies the rationality and reference value of the test analysis in this paper.

A large quantity of cement kiln dust (CKD) is produced annually during the production of Portland cement. The majority of the produced CKD remains unused except in specific cases related to soil stabilization projects. The current research investigates the production of self-compacting concrete (SCC) mixtures, in which CKD is used as a substitute for cement in different weight proportions, 3 %, 6 %, 9 %, 12 %, and 15 %. The hardened mechanical properties of SCC, such as compressive strength, splitting tensile strength, and flexural strength, as well as the fresh state characteristics (i.e., slump flow diameter, T500, V-funnel, and L-box tests), were recorded and compared with the control mixture which was entirely cast using cement. Results revealed that with an increase in the CKD content beyond 6 %, the slump flow diameter of SCC mixtures significantly decreased. Also, the increase ratios in the V-Funnel flow time for self-compacting concrete mixtures, when replacing cement with CKD ratios of 3 %, 6 %, 9 %, 12 %, and 15 %, were 13.3 %, 30 %, 46 %, 58 %, and 66.7 % respectively, compared with the reference mixture. Additionally, the impact behavior of two-way SCC slabs cast using CKD ratios ranging from 3 to 15 % and internally strengthened using various patterns of recycled plastic mesh was investigated. Strengthening the SCC slabs using two layers of recycled plastic grids proved to be effective in preventing the projectile from penetrating the whole thickness of the SCC slabs, regardless of the CKD content.

Granular materials - aggregates of many discrete, disconnected solid particles - are ubiquitous in natural and industrial settings. Predictive models for their behavior have wide ranging applications, e.g. in defense, mining, construction, pharmaceuticals, and the exploration of planetary surfaces. In many of these applications, granular materials mix and interact with liquids and gases, changing their effective behavior in non -intuitive ways. Although such materials have been studied for more than a century, a unified description of their behaviors remains elusive. In this work, we develop a model for granular materials and mixtures that is usable under particularly challenging conditions: high -velocity impact events. This model combines descriptions for the many deformation mechanisms that are activated during impact - particle fracture and breakage; pore collapse and dilation; shock loading; and pore fluid coupling - within a thermo-mechanical framework based on poromechanics and mixture theory. This approach allows for simultaneous modeling of the granular material and the pore fluid, and includes both their independent motions and their complex interactions. A general form of the model is presented alongside its specific application to two types of sands that have been studied in the literature. The model predictions are shown to closely match experimental observation of these materials through several GPa stresses, and simulations are shown to capture the different dynamic responses of dry and fully -saturated sand to projectile impacts at 1.3 km/s.

Flexible damping technology considering aseismic materials and aseismic structures seems be a good solution for engineering structures. In this study, a constrained damping structure for underground tunnel lining, using a rubber-sand-concrete (RSC) as the aseismic material, is proposed. The aseismic performances of constrained damping structure were investigated by a series of hammer impact tests. The damping layer thickness and shape effects on the aseismic performance such as effective duration and acceleration amplitude of time-domain analysis, composite loss factor and damping ratio of the transfer function analysis, and total vibration level of octave spectrum analysis were discussed. The hammer impact tests revealed that the relationship between the aseismic performance and damping layer thickness was not linear, and that the hollow damping layer had a better aseismic performance than the flat damping layer one. The aseismic performances of constrained damping structure under different seismicity magnitudes and geological conditions were investigated. The effects of the peak ground acceleration (PGA) and tunnel overburden depth on the aseismic performances such as the maximum principal stress and equivalent plastic strain (PEEQ) were discussed. The numerical results show the constrained damping structure proposed in this paper has a good aseismic performance, with PGA in the range (0.2-1.2)g and tunnel overburden depth in the range of 0-300 m. (c) 2024 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/).

Soil-embedded vehicle barriers, such as W-beam guardrail systems, play a pivotal role in transportation safety, mitigating the risks associated with vehicular collisions with roadside hazards. The efficacy of these barriers greatly depends on the pile-soil system's kinetic energy dissipation capability during vehicular impacts. However, a comprehensive understanding of how soil strength, embedment depth, and impact velocity collectively govern the dynamic behavior of the pile-soil system remains a gap in current research. This study explores the dynamics of lateral impacts on piles embedded in various granular soils. The process of dynamic lateral impact and interaction between the pile and the soil was modeled using the Updated Lagrangian Finite Element Method (UL-FEM). A damage-based element erosion algorithm was incorporated into the model to accommodate severe mesh distortions and element entanglements of the soil material brought by the pile impact. Validation against well-documented large-scale physical impact tests ascertained the model's fidelity. Our findings elucidate the significant differences in resistive forces between piles in strong versus weak granular soils - notably, the former exhibited resistive forces roughly double their weaker counterparts under equivalent embedment depths and varied impact velocities. Intriguingly, a stiff pile in weak soil necessitates nearly double the embedment depth to match the energy dissipation of its strong-soil counterpart. Furthermore, the study discerned consistent depth of rotation point ranges for piles embedded in distinct soil strengths, regardless of embedment depth and impact velocity.

This study investigates the behavior of rockfall protection on a reinforced concrete semicircular shed against impulse excitation forces by using finite element software ABAQUS and experimental analysis on a free-fall impact test machine. There is limited field knowledge about the response of rockfall protection reinforced concrete semicircular sheds under free-fall impact. The experiments are carried out through the 0.5-m center-to-center diameter of a semicircular reinforced concrete (RC) shed which has a 1.2-m length. The shape of the impactor is cylindrical with a free-fall height of 2.4 m on a semicircular reinforced concrete shed from a free-fall impact test machine. Conventional explicit analysis in finite element software ABAQUS was employed. The concrete damaged plasticity, Johnson-Cook plasticity, and Drucker-Prager models were used to mimic the reaction behavior of concrete, reinforcement, and soil, respectively. The findings from the finite element program ABAQUS were compared to the experimental data, which were found to be in close agreement. Furthermore, the simulation was carried out on the effect of important parameters such as variation in the velocity of the impactor, lining thickness, and length of the RC shed to predict the behavior of reinforced concrete shed.