The root-knot nematode, Meloidogyne javanica, is one of the most damaging plant-parasitic nematodes, affecting chickpea and causing substantial yield losses worldwide. The damage potential and population dynamics of this nematode in chickpea in Ethiopia have yet to be investigated. In this study, six chickpea cultivars were tested using 12 ranges of initial population densities (Pi) of M. javanica second-stage juveniles (J2): 0, 0.125, 0.25, 0.5, 1, 2, 4, 8, 16, 32, 64 and 128 J2 (g dry soil)-1 in a controlled glasshouse pot experiment. The Seinhorst yield loss and population dynamics models were fitted to describe population development and the effect on different measured growth variables. The tolerance limit (TTFW) for total fresh weight ranged from 0.05 to 1.22 J2 (g dry soil)-1, with corresponding yield losses ranging from 31 to 64%. The minimum yield for seed weight (mSW) ranged from 0.29 to 0.61, with estimated yield losses of 71 and 39%. The 'Haberu' and 'Geletu' cultivars were considered good hosts, with maximum population densities (M) of 16.27 and 5.64 J2 (g dry soil)-1 and maximum multiplication rate (a) values of 6.25 and 9.23, respectively. All other cultivars are moderate hosts for M. javanica; therefore, it is crucial to initiate chickpea-breeding strategies to manage the tropical root-knot nematode M. javanica in Ethiopia.

Seismic fragility denotes the probabilities of a system exceeding some prescribed damage levels under a range of seismic intensities. Classical seismic fragility studies in slope engineering usually construct fragility functions by making some assumptions for fragility curve shape, and always neglect spatial variability of soil materials. In this study, an assumption-free method on the basis of probability density evolution theory (PDET) is proposed for seismic fragility assessment of slopes. The random input earthquakes and spatially-variable soil parameters in slope are simultaneously quantified. By the proposed method, assumption-free fragility curves of a slope are established without limiting the fragility curve shape. The obtained fragility results are also compared with those from two classic parametric fragility methods (linear regression and maximum likelihood estimation) and Monte Carlo simulation. The results demonstrate that the proposed assumption-free method has potential to gives more rigorous and accurate fragility results than classical parametric fragility analysis methods. With the proposed method, more reliable fragility results can be obtained for slope seismic risk assessment.

Offshore wind turbines, crucial for global electricity generation, face significant challenges from harsh marine conditions, including strong wind, waves, and uneven seabeds. To optimize the foundation solution, this study investigates the lateral performance of helical monopiles, comparing conventional monopiles under cyclic loading, with a focus on variations in pile configuration and soil conditions. Model-scale experiments were conducted with helical piles subjected to both monotonic and one-way cyclic loading conditions. Key variations in the study include three soil densities (Dr = 35 %, 55 %, and 75 %), along with different slope conditions (Flat, 1V:5H, 1V:3H, 1V:2H) and pile positions (c = 0Dp, 2.5Dp, 5Dp, 7.5Dp). Additionally, the effect of load amplitudes (xi b = 50 %, 40 %, and 30 %) applied at a frequency of 0.25Hz for over 1000 cycles was examined. Results showed that helical piles outperformed conventional monopiles, exhibiting up to 25 % higher lateral load capacity, 30 % less accumulated rotation, and 20 % greater cyclic stiffness, especially in dense soils. Furthermore, the analysis revealed that the performance of helical piles significantly improved when placed nearer to the slope crest and in denser soils. Numerical simulations using PLAXIS 3D confirmed these experimental findings, demonstrating that helical piles consistently maintain superior lateral resistance and cyclic performance under varying loading conditions and slope configurations. This study underscores the potential of helical piles to enhance the stability ad performance of offshore wind turbine foundations, offering a more robust and efficient alternative to monopile systems.

In this study, impact compression tests on low-temperature concrete were conducted using a split Hopkinson pressure bar. The impacts of low temperatures on the strength, fractal, and energy characteristics of concrete were analyzed. The damage evolution mechanism of the microcrack density was discussed based on microscopic damage theory and microscopic tests. The results demonstrated that the impact fractal dimension and energy dissipation density of low-temperature concrete were positively correlated with the strain rate. The strain rate sensitivity of the impact fractal dimension was significantly affected by low temperature at low strain rates; however, low temperature had little effect at high strain rates. The pore water transformed into ice at negative temperatures, the fracture energy of the concrete increased, and the energy dissipation density increased. More than 50 % of the capillary and free water inside the concrete was frozen at -10 degrees C; approximately 30 % of the capillary and free water and 65 % of bound water did not freeze when the temperature was -30 degrees C. The macropores did not collapse under the action of ice filling at high strain rates; however, microcracks were generated around them. With a decreasing temperature, the threshold stress for microcrack propagation increased, crack propagation required more energy, and the microcrack density decreased.

The soil fabric varies significantly depending on the deposition process that forms the grain skeleton. Each deposition method produces a specific type of soil fabric, which can be linked to a particular soil density. When represented as relative density, determined using limit densities from standard index tests, a wide range of relative densities can be observed for different sands produced by the same deposition method. The influence of this variation in relative density, resulting from a single deposition method, on the development of the excess pore water pressure (PWP) should be further investigated. A fast testing of the excess PWP accumulation in sandy soils during undrained cyclic shearing can be easily performed using the newly developed PWP Tester. In the PWP Tester, specimens are prepared through sedimentation in water, which yields a comparable fabric in different sands but significantly different relative densities. Despite these relative density differences, the rate of the excess PWP evolution during undrained shearing is remarkably similar among different sands. This indicates that relative density should not be regarded as a primary factor influencing the development of the excess PWP and that the soil fabric plays equal or even a greater role.

This study investigates the seismic response of a reinforced concrete (RC) tunnel using two-dimensional plane strain finite element models calibrated and validated against experimental results. A comprehensive parametric study is then conducted to explore the influence of tunnel-soil flexibility ratio, soil relative density, Arias intensity of the input motion, and ground motion components on the seismic soil-structure interaction (SSI). The results demonstrated that the flexibility ratio and racking coefficient increase with overburden height, while soil deformations decrease. Acceleration amplification factors rise from the bottom soil to the ground surface, with dense soil showing higher amplification especially in the regions at and near the tunnel field. The horizontal amplification factor exhibits greater variability with increasing seismic energy intensity, and the effect of the vertical motion becomes more pronounced near the structure. The vertical amplification factor is lowest for the horizontal component, while the vertical and combined components exhibit higher values influenced by the presence of the tunnel with lower earthquake intensity. Soil relative density significantly influences the vertical and lateral pressures on the tunnel, with dense sand causing maximum vertical pressures on the top slab and walls. The vertical earthquake component has a greater impact on the tunnel's top slab pressure distribution than the horizontal component. Seismic bending moments are influenced by earthquake components, with the vertical component leading to the greatest positive bending moment values in the middle of the roof slab. Vertical soil deformation is significantly affected by the horizontal input motion component, whereas the vertical component minimally affects lateral soil deformation. These findings underscore the importance of capturing stress-strain response under cyclic loading, particularly near the tunnel crown, where complex stress interactions lead to increased variability in behavior.

To address the challenges of extraction difficulties and penetration risks associated with traditional spudcan jackup platforms, a new jack-up platform featuring a pile-leg mat foundation is proposed. The horizontal bearing capacity of hybrid foundations under the influence of dynamic loads is a critical factor that requires close attention. This research numerically examined the dynamic response of a hybrid foundation to horizontal cyclic loading on a sandy seabed. A user-defined subroutine was employed to incorporate the Cyclic Mobility (CM) model within Abaqus, facilitating the analysis of sand response under different densities. The horizontal cyclic bearing capacities of the foundation were investigated considering the effects of different loading conditions, sand density, and pile-leg penetration depth. Simulation results indicate that the cyclic loading amplitude, frequency, and load mode significantly influence the generation of soil excess pore water pressure (EPWP), subsequently affecting foundation displacement and unloading stiffness. Under cyclic loading, the loose sandy seabed shows the most pronounced fluctuations in EPWP and effective stress, leading to surface soil liquefaction. While surface soil in medium-dense and dense sand conditions remains non-liquefied, their effective stress still varies significantly. Increasing the pile-leg penetration depth enhances the foundation's horizontal bearing capacity while affecting its vertical bearing capacity slightly.

Earthen construction is one of the earliest and most ubiquitous forms of building. Compressed stabilized earth blocks (CSEBs) combine compressed components including inorganic soil, water, and a stabilizer such as Portland cement, and can achieve greater strength than other earthen construction methods. Typically, site-specific soil comprises the bulk material in CSEB construction, which minimizes the quantity of construction materials that need to be provided from off-site and motivates this type of building material for remote locations. However, onsite manufacturing and innate soil variability increase the variability of CSEB mechanical properties compared to more standardized building materials. This study characterizes the effects of varying mix compositions and initial compressions on the density, compressive strength, and variability of compressed stabilized earth cylinders (CSECs) created from sandy soil. CSEC samples comprising nine mix compositions and four levels of initial compression provide data for the (i) statistical evaluation of strength, density, and variability and (ii) development of predictive equations for density and compressive strength, with R2 values of 0.90 and 0.89, respectively.

This study explores the performance of finned monopiles as an innovative foundation solution for Offshore Wind Turbines subjected to cyclic loading under varying seabed conditions. Traditional monopiles face challenges related to stability when installed on sloped terrains, which are common in offshore environments. To address this, the research investigates the effectiveness of rectangular fins attached along the monopile's length to improve lateral resistance and reduce accumulated rotation. Experimental and numerical analyses were conducted across different slope gradients (flat, 1V:5H, 1V:3H, 1V:2H), pile positions (0Dp, 2.5Dp, 5Dp, 7.5Dp), and soil densities (35%, 55%, 75%), applying cyclic loading at 0.25 Hz over 1000 cycles with lateral load amplitudes (xi b) of 30%, 40%, and 50%. This study is the first to investigate finned monopiles under cyclic loading on sloping seabed conditions, demonstrating a 30-60% improvement in lateral resistance by increasing the passive soil resistance by reducing the rotation compared to monopiles. This work addresses the challenges of Offshore Wind Turbine foundations in complex topographies. Numerical modeling using PLAXIS 3D closely aligned with experimental findings, confirming the effectiveness of finned monopiles in enhancing stability on sloped seabeds. These findings suggest that finned piles offer a robust foundation alternative for Offshore Wind Turbines, particularly in challenging environments with variable seabed topography.

In this research, the effect of using alpha fibres on the physico-mechanical properties of compressed earth bricks (CEBs) was investigated. CEBs were produced using soil, lime and different amounts (0%, 0.5%, 1%, 1.5% and 2%) of raw (RAF) or treated alpha fibres (TAF). First, the diameter, density and water absorption of RAF and TAF were determined. Then, the produced CEBs reinforced by these fibres were subjected to compressive strength, thermal test, density and capillarity water absorption tests. The obtained results showed that the addition of RAF and TAF leads to a reduction of the thermal conductivity by 33% and 31%, respectively. The finding also indicated that the density was decreased by 26% and 17% with the inclusion of TAF and RAF respectively. Besides, the compressive strength was reduced and water absorption coefficient was increased when fibres reinforced CEBs but remaining within the standard's recommended limits. Moreover, the addition of fibre improves the acoustic properties of samples by 98%. The CEBs developed in this paper could be an alternative to other more common building materials, which would lead to a reduction of energy demand and environmental problems.