In geotechnical engineering, the small-strain shear modulus and its attenuation characteristics are pivotal for analyzing and evaluating soil vibration responses to various engineering construction projects. This study conducts the resonant column test on undisturbed fissured clay samples, exploring the impacts of fissure inclination and confining pressure on the shear modulus in small-strain range. Results indicated that the shear modulus and its attenuation behavior in undisturbed fissured clay are substantially affected by both the fissure inclination angle and the confining pressure. With constant confining pressure, the shear modulus increases as the fissure inclination angle grows, reaching its maximum value at a fissure angle of 90 degrees. In addition, as the confining pressure rises, there is a notable increase in the shear modulus and a corresponding reduction in the decay rate. Through the threshold strain, the elastic deformation of the specimen increases as the fissure inclination angle increases, and the confining pressure increases the ability of the fissured soil to deform at small strains elastically. Based on the acquired data, this research analyzes the relationship between the fitting parameters A and N and the fissure angle in the context of the Harding-Drnevich formula. Consequently, a mathematical model based on the fissure inclination angle and the effective confining stress was established to predict the maximum dynamic shear modulus (Gmax) and decay attributes of undisturbed fissured clay. Additionally, the study offers a comparative analysis of the maximum shear modulus and its attenuation features in clay with varied degrees of fissure development. The stiffness anisotropy is related to the orientation of particles and the normalized decay rate of the fissured clay has a certain relationship with the fissure density.

Various anchors are used to withstand uplift forces for offshore and onshore structures on which research is going on for almost the last six decades. In the present study, it has been attempted to obtain the responses of inclined anchors based on numerical studies. Uplift capacities of model anchor plates having dimensions of 0.025 m x 0.025 m, 0.050 m x 0.050 m, and 0.075 m x 0.075 m with embedment ratios of 1, 2, and 3 and inclination angles 30 degrees, 45 degrees, and 60 degrees with vertical, have been obtained under cyclic loading with 0.2 Hz, 0.5 Hz frequency and 0.002 m, 0.005 m amplitude. The soil bed has been made of locally available clay and the anchors are of mild steel. The numerical analysis has been carried out by ABAQUS, considering all relevant parameters of soil, plate size and inclination angle, and embedment ratio of anchor and also for different frequencies and amplitudes of loading. The variation of ultimate pullout capacity has been studied by varying these parameters. It has been observed that the ultimate capacity under pullout increases significantly with increase in the dimensions of the plate, the embedment ratio, and also the angle of inclination of the anchor with vertical.

An important characteristic of some clays is their abundance of fissures. In the case study reported here, to investigate how the fissure inclination angle affects the deformation and strength of fissured clay, samples of undisturbed fissured clay with different inclination angles of its inherent fissures (0 degrees, 45 degrees, and 90 degrees) were subjected to consolidated undrained plane-strain shear tests using a true triaxial apparatus. Moreover, consolidated undrained triaxial tests were carried out on samples with the same inclination angles for comparison. The results showed that compared with the triaxial state, the degree of fissure influence on samples with different fissure angles is different under plane strain, which weakens the influence of the fissure inclination angle on the soil's mechanical behavior. Under the designed consolidation pressures, the peak stress of the 45 degrees fissured soil samples was the smallest, with a stress-strain curve that exhibits strain softening. The 0 degrees fissured soil samples exhibited the highest peak stress, with a stress-strain curve that exhibits strain hardening. The 90 degrees fissured soil samples fell in between, with a stress-strain curve that exhibits a relatively stable trend. The intermediate principal stress coefficient b-value showed different trends at different fissure angles, which also reflects the influence of fissure dip angle. According to the von Mises and Lade-Duncan strength criteria, the generalized plane-strain criterion for fissured soil was obtained. The dip angle of the shear band was calculated from Mohr-Coulomb theory, and the difference between the calculated and measured dip angles was found to be small.