An internal explosion may cause severe damage to an underground and surface ground structures. The intensity of the blast plays a substantial role in the damage to the structures, the configuration of the structure, material properties, and geometry of materials. There are several ways for a structure to be protect against blast loads. A tunnel could be protected employing the protective layer, directly located on the top of the structure. The influence of utilizing a protective layer, made of geofoam could appease the adverse effects of an internal explosion and decline vibrations when it comes to the surface ground. The modeling procedure used the coupled Eulerian-Lagrangian in Abaqus/Explicit. Lagrangian elements have been used for modeling soil and reinforced tunnel and trinitrotoluene as Eulerian elements. Drucker-Prager plasticity, Holmquist-Johnson and Johnson-Cook plasticity models were simulated for the stress-strain response of soil, concrete, and reinforcement, respectively. In addition, Jones-Wilkins-Lee equation of state used for the pressure-volume relation of TNT. As the results show, while explosion waves scatter inside tunnel and penetrate among top layers of soil, soil and lining without a protective layer experienced severe deformation and blast waves influenced surface ground structures negatively. Indeed, the more charge weight, the more deformation on tunnel lining and structures. It is observed that increasing geofoam thickness worked up to a certain thickness and semi-circular geofoam on top of the structure fulfilled expectations.

Frost damage is one of the main factors affecting the stability of canal slopes in cold regions. To alleviate the damage, laying protective layers during the construction process has become an indispensable measure. In this study, two slope models were constructed using polyester geotextiles (slope I) and composite geomembranes (slope II) as the protective layer. Additionally, the insulation board in the control group were laid on specific to examine their anti-frost effect. The temperature, frozen depth, and frost deformations of slope models during the freeze-thaw process were recorded and analyzed. Results suggest that the temperature of slope II is relatively lower than that of slope I in the freezing process. The temperature reduction at all monitoring sections of slope II are larger than that of slope I. The slope I exhibits a significant decrease in maximum frozen depth and maximum frost deformation. In particular, the with the maximum frost deformation is independent of the type of protective layer, which all occurs in the middle of the slopes. The maximum frost deformations of slope models are 33.60 mm and 37.69 mm, respectively after laying the polyester geotextiles and composite geomembranes. Therefore, the polyester geotextiles have more advantages in reducing frost deformation than composite geomembranes. Additionally, if the insulation board and polyester geotextiles are laid together inside the slope, the maximum frost deformation can be further reduced to 9.72 mm. This study will help in the design and construction of canal slopes in cold regions.

Under the influence of perennial dynamics of soil thawing depth, the upper layer of permafrost periodically thaws and becomes a part of the soil profile in the permafrost zone. In this case, the horizon, which is either frozen or thawed and has a thickness of several tens of centimeters, displays an elevated ice content (moisture). This horizon between the lower boundary of the active layer and the permafrost is named a protective layer or a transient permafrost layer and functions as a buffer that hinders thawing of the ice complex with its high ice content. The study of moisture using soil-regime methods and budget calculations showed that the protective layer of permafrost in sandy and loamy soils (at the depth of 1.5-5 m) contains from 25 to 60 mm (on average, 30 mm) of water in each 10-cm-thick layer of frozen soils under different types of forests in Central Yakutia. An increase in the seasonal thawing depth of permafrost-affected soils under conditions of global climate warming and anthropogenic impacts (forest fires, destruction of forest cover, etc.) causes degradation of the protective layer. The purpose of this article is to show the effect of increasing seasonal thawing depth of permafrost-affected soils on changes in the water content and water budget in permafrost areas because of the release of moisture stored in the protective layer in the context of global climate change. It was found that with an increase in the seasonal thawing depth, the protective layer should release a significant amount of water preserved in permafrost, which may change the water budget of permafrost territories. As calculations show, with an increase in the soil seasonal thawing depth by 20-30 cm on the interfluve areas, the volume of water entering the basins of nearby thermokarst depressions (alases) and rivers from frozen soils may reach 60000-90000 m(3)/km(2). The obtained results can be used in modeling and predicting the dynamics of permafrost environments under the global climate change.