An approximation technique is considered for computing transmission and reflection coefficients for plane waves propagating through stratified slabs. The propagation of elastic pulse through a planar slab is derived from first principles using straightforward time-dependent method. The paper ends with calculations of enhancement factor for the elastic plane wave and it is shown that it depends on the velocity ratio of the wave in two different media but not the incident wave form. The result, valid for quite arbitrary incident pulses and quite arbitrary slab in homogeneities, agrees with that obtained by time-independent methods, but uses more elementary methods.

An approximation technique is considered for computing transmission and reflection coefficients for propagation of an elastic pulse through a planar slab of finite width. The propagation of elastic pulse through a planar slab is derived from first principles using straightforward time-dependent method. The paper ends with calculations of enhancement factor for the elastic plane wave and it is shown that it depends on the velocity ratio of the wave in two different media but not the incident wave form. The result, valid for quite arbitrary incident pulses and quite arbitrary slab inhomogeneities, agrees with that obtained by time-independent methods, but uses more elementary methods.

One of the most important stages of walnut processing is cracking the hard skin and shelling it. In this research, to reduce the mechanical damage and improve the extraction quality of walnut kernels during shelling, the fracture properties of the walnut shell were evaluated in a new uniaxial compressive loading test by creating a lateral deformation limitation called the enclosed. The fracture properties of walnut shell for the genotype of hard shell walnut were investigated due to the variables of loading mode, loading direction, and size of a walnut. The results showed that the effect of the state of walnut loading (free and enclosed) on the fracture force and fracture energy was significant at 1% and 5% probability levels, respectively. The breaking force of the hard shell walnut was 273.96 and 441.47 N for free and enclosed loading states, respectively. The breaking force along the longitudinal axis (392.56 N) was significantly more than in other loading directions, such as thickness or suture on the skin (347.85 N) and width (332.65 N). In general, observations showed that in the case of enclosed walnut loading, the rupture development on the shell surface was more than that of freeloading, which can be used as an idea for making a high-performance nutcracker machine.

Traditional techniques such as burning leads to some highly durable non-degradable synthetic materials that cause unrepairable environmental damages by releasing heavy metals such as arsenic, chromium, lead, manganese, and nickel. Today, scrap tires are used as lightweight alternative materials in many applications such as retaining wall backfilling. In the present study, several laboratory models were carried out to evaluate the stability of retaining walls reinforced with plate anchors. Then, the effect of adding different contents (10 and 20 wt. %) of crumb rubber to fill of a mechanically stabilized retaining wall with plate anchors were investigated including its effect on bearing capacity and wall horizontal displacements during static loading. To visualize the critical slip surface of the wall, particle image velocimetry (PIV) technique was employed. The results showed that the circular anchor plates provide a higher bearing capacity and wall stability in comparison to square plates. Also, it was found that the backfill with 10 wt. % crumb rubber provides the wall with the maximum bearing capacity. In addition, increasing the weight percentage of crumb rubber to 20 wt. % resulted in a significant reduction in bearing capacity and horizontal displacement of the wall, which occurred due to a decrease in lateral pressure against the whole walls. Moreover, an increase in weight percent of crumb rubber results in a decrease in failure wedge formation and expansion of wall slip surface while the failure wedge is not formed in mix of sand-20 wt. % crumb rubber.

Planar failure is one of the most common types of riverbank destruction worldwide. Annually, it destroys much fertile soil and leads to the collapse of nearby infrastructure. The angle of riverbanks after failure plays an important role in defining the geometry of a failed block when analyzing the stability of this type of failure. Studies published thus far estimate the angle of the riverbanks after planar mass failure, but they fall short because they only can be used for homogeneous bank material. No relation has been introduced to estimate the angle of different layers in a multi-layered river bank. This research used a physical model in a laboratory consisting of two layers of soil and measured the angle of failure of the bank for different soil layers. Two relationships to estimate the amount of upper and lower bank failure angles are introduced using two-thirds of the measured values for each layer. Evaluating these relationships using one-third of the measured values results in a mean relative error of 0.14 and 0.015 for the upper and lower bank layers, respectively. Another relationship is introduced and its results compared with those obtained from available relationships using the mean of physical and mechanical specifications of the banks and by imaging a homogenous river bank. The results show that the river bank angle of failure after planar mass failure is better estimated using the new relationship and it can be used to estimate the angle of the river bank for both multilayered and homogenous river banks.

Riverbank erosion, land loss and associated sedimentation are river engineering and water resources management problems of global significance. The ability to predict riverbank stability on eroding rivers is the prerequisite of developing a channel width adjustment model and is essential for estimating riverbank erosion and associated sedimentation. In this research, a detailed model for stability analysis of riverbanks is introduced. Contrary to most available models developed based only on one type of planar or rotational failure, the new model includes both these types of failure, providing the ability to analysis bank stability using other available methods and compares the results. Furthermore, this new, unique model has the ability to analyze riverbank stability against cantilever failure. The most suitable analysis method was first selected based on bank material characteristics and stratification and the height and slope angle of the riverbank. The stability of the riverbank was then analyzed based on probable failure methods. The application of the new model providing examples of different types of failure is described.