mohammadjavad mashin chian

Effective seepage management is crucial for the structural integrity and operational safety of earth dams. This paper presents a detailed evaluation of seepage control strategies implemented at the Shahid Yaghoubi and Maloo dams in Khorasan Razavi province, Iran. Our study utilizes hydrological and structural data to assess the impact of specific interventions. For this purpose, numerical analysis methods and commercial GeoStudio software have been used. At the Shahid Yaghoubi dam, the application of a geomembrane on the upstream face resulted in a 15% reduction in seepage flow, while the addition of a cut-off wall downstream of the dam core led to a 35% decrease in seepage. Despite these improvements, the critical hydraulic gradient in the downstream drain remained unchanged, underscoring the complexity of seepage dynamics within dam structures. Similarly, at the Maloo dam, the installation of a geomembrane and the modification of the cut-off wall height beneath the dam core achieved reductions in seepage of 6% and 25%, respectively. These results highlight the importance of tailored, site-specific adaptations in effectively managing seepage. This research provides significant insights into the optimization of seepage control measures, contributing to the development of more durable and safer earth dam structures.

The piezocone penetration test is commonly used to measure pore water pressure, identify a soil’s profile and estimate its material properties. Depending on the soil type, ranging from clay to sand, undrained, partially drained, or drained conditions may occur during cone penetration. In silt and sand–clay mixtures, the piezocone penetration is characterized by partially drained conditions, which are often neglected in data interpretation. The effect of drainage on piezocone measurements has been mainly studied experimentally. Numerical analyses are rare because taking into account large soil deformations, soil–water and soil–structure interactions, and nonlinear soil behavior are still challenging tasks. In this paper, using advanced hypoplastic constitutive model and ABAQUS finite element software large deformations and nonlinear behavior of soil during penetration was modeled and behavior of firoozkooh saturated sandy soil in different drainage conditions and relative densities was analyzed. Then, using the obtained results, the range of influence of cone penetration on the surrounding soil and the range of partial drainage conditions for Firoozkooh sandy soil were investigated. It was also shown that drainage condition and density had a significant effect on the affected soil area and the trend of changes in excess pore water pressure.

Pile foundations are one of the most important foundation systems in geotechnical engineering. The design of pile foundations and the estimation of pile bearing capacity have been improved considerably over the years. However, due to inherent soil uncertainties and disturbances, most theoretical approaches have been mainly based on assumptions and simplifications. Resulting in a wide range of bearing capacity values, different design methods establish the existence of inherent soil variability and model error in bearing capacity prediction. The cone penetration test (CPT) is considered as one of the most useful in situ tests for the characterization of soil. Due to the similarity between the cone and the pile, estimation of pile capacity from CPT data is among its most common applications. This paper proposes a model for predicting the bearing capacity of piles in clayey soils using data that were collected from 62 practical cases of pile loading tests and the corresponding cone penetration tests. The reliability of proposed model was compared with other methods suggested in the literature. In order to evaluate the reliability of the proposed model, Monte Carlo sampling method was used. Results show that the proposed model in this research together with UniCone and Schmertmann methods have the highest accuracy and reliability.

Pile foundations are widely used to ensure the stability of structures subjected to seismic excitation. Numerous structures and foundations in soil-pile-structure systems have been destroyed during occurrence of earthquakes. Because of complexities involved in soil-pile interaction problems and the lack of precise methods, it is necessary to use numerical methods for analyzing soil-pile interaction problems. There are several factors affecting the dynamic response of a pile in soil-pile system. These factors can be divided into three main categories: geometrical factors, material properties, and load characteristics. Studying the effects and importance of these factors in the response of the pile will help geotechnical engineers to optimize their design. In this research, three-dimensional modeling has been developed using FLAC3D computer program, and the effects of various soil and pile properties on the dynamic behavior of a single pile in clayey soils are evaluated. One of the most important subjects in the numerical modeling of soil-pile system dynamic response is the constitutive model considered for the soil. This strongly affects the accuracy of results. In this study a softening model has been used for the behavior of the soil under dynamic loads.Sinusoidal harmonic loading has been applied to the model base as the acceleration time history, and the variations of bending moments, shear forces, and displacements along the pile are obtained for all analyses carried out in this study.The results show that kinematic interaction coefficient depends on the loading characteristics and in the high frequencies head pile response is lower than free field.