A fast reduction of a reservoir level may result in instability of an earth dam caused by the high pore water pressures that remain relatively high in the embankment. Moreover, the dissipation of the accumulated pore water pressures is highly dependent on the permeability of the materials used for the embankment and the storage characteristics of the reservoir. Therefore, in the design of embankment dams, the stability analysis under rapid drawdown loading conditions is an important design case. In this study, the influence of different permeability rates on dam stability under different cases of rapid drawdownwas investigated using the finite element method in SEEP/W and SLOPE/W of the GeoStudio with a case of the Lugoda dam in Ndembera catchment, Tanzania. The modeling process considers the time-dependent hydraulic conditions and the transient flow conditions using different water levels during rapid drawdown for evaluation of the factor of safety. From the 1m per day drawdown rate; the lowest minimum factor of safety value (0.90) was obtained from the 10 ^-7 m/s material permeability of the upstream zone of the dam. It means that, at a drawdown rate of 1m per day, there is a potential for failure of the embankment if the hydraulic conductivity value will be somewhere below 10 ^-6 m/s.

One of the most important and urgent problems is constructing roads in difficult soil conditions, ensuring their strength, reliability, and normal operation. To create an efficient and competitive transport infrastructure in Kazakhstan, the State Programme of Infrastructural Development “Nurly Zhol” for 2020–2025 was developed. Its main objectives are to improve the technological, scientific, and methodological base, provide resources, and to attract “Big Transit”. The paper presents the details of the survey carried out in one of road construction areas. Irrigation canals and periodic and permanent watercourses represent the hydrographic network of the construction site. The analysis of these features and field tests were included in the research. Stamp tests were performed to analyse mechanical properties of embankment soil to provide more reliable information on the mechanical properties of the soil. Structural and technological solutions were adopted based on the field tests and surveys of hydrological conditions. A numerical simulation was used to determine the stability of the road embankment, the results of which showed maximum deformations of 4.5 mm during the operation of road transport. Geosynthetic material was used to reinforce the subgrade. The results of the study have shown that the analysis of factors affecting the stability of engineering structures on difficult soil conditions helps to achieve some improvement.