Frost heaving damage of canal lining in cold and dry areas is one of the important causes of canal leakage. In this paper, based on the bending theory of thin plate, a mechanical model of canal lining under the action of frost heaving force is established and solved. Through parametric and engineering case analysis, the following conclusions are drawn: under the action of frost heaving force, the bending moment, shear force, and internal force of the slope plate show a nonuniform distribution, and the maximum values of bending moment M_x and normal stress σ_x are close to the bottom third of the slope, which is consistent with the existing research and engineering practice. Compared with the theory of beam, the results of the theory of thin plates show that the internal forces and stresses increase at the free boundary (longitudinal expansion joint). The bending moment M_xy and stress τ_xy are maximum at the four corners of the plate: although the numerical magnitude is lower than that of M_x, it may cause stress concentration to damage the lining plate and thus cause break. The shear force at the longitudinal expansion joint may lead to fracture of the joint material, which needs to be considered in the design process. Due to the uniform distribution of the frost heaving force on the bottom plate lining, its deflection, internal forces, and stresses also show a uniform distribution. The research results can provide scientific reference for the design and operation and maintenance of water transmission canal lining in cold areas.

To carry out engineering construction in a permafrost area, it is of great importance to grasp the spatial distribution of permafrost and its hydrothermal characteristics within the scope of engineering activities. Compared with the continuous permafrost area, the permafrost distribution in discontinuous permafrost area is complicated due to existence of island talik, which causes highly poor continuity and uniformity of ground hydrothermal conditions and brings great difficulty and uncertainty to the engineering geological investigation. In the present study, the spatial distribution of permafrost and the freeze-thaw process of shallow ground at the I-stage terrace of a river on the Qinghai-Tibet Plateau were studied based on field investigation including drilling, electrical resistivity tomography, and borehole temperature measurement. The results show that the relict permafrost, patchy permafrost, and island talik are distributed in the limited range of the study area. Among them, the buried depth of relict permafrost layer is in the range of 7 ~ 14 m, while the patchy permafrost layer is in the range of 3.0 ~ 17.0 m depth, and the mean annual ground temperature of both is close to -0.1°C, which belongs to extremely high-temperature permafrost. The seasonal freezing/thawing depths of shallow ground within the relict permafrost, patchy permafrost, and island talik range from 2.5 to 3.0 m. The freezing period of the seasonal freezing layer is 5.5 months, while the thawing period of the seasonal thawing layer is 6 months. The complex plane and spatial distribution of permafrost in the field are closely related to local factors such as topography, geomorphology, groundwater, and lithology of shallow ground. It is believed that the formation of the island talik in the study area is controlled by solar radiation and precipitation infiltration.

Tunnel excavation in water-rich and saturated loess layers often encounters a series of engineering disasters, including surface settlement, large deformations of surrounding rock, collapses, water inrushes, mud inrushes, and lining cracks. This paper presents an analogy of 16 cases of instability and collapse of surrounding rock during the excavation of water-rich loess tunnels in China’s loess regions. The weight of influence of various factors affecting the stability of surrounding rocks has been analyzed based on the Fuzzy Analytic Hierarchy Process (FAHP), addressing the engineering challenges encountered during the construction of the Tuanjie Tunnel. Measures such as deep well-point dewatering of the surface, reinforcement of locking foot anchors, and construction treatment with large arch feet are proposed. The effectiveness of these treatments is then monitored and analyzed. The results show that after 30 days of dewatering, the average water content of the surrounding rock decreased from 28.8% to 22.3%, transforming the surrounding rock from a soft plastic state to a hard plastic state. Phenomena such as mud inrushes at the tunnel face and water seepage through the lining are significantly reduced, and the self-stabilizing capacity of the surrounding rock is markedly improved. By optimizing the excavation method and enhancing support parameters, the construction progress rate for Grade VI surrounding rock has increased from 10–15 m per month to 40 m per month, validating the effectiveness of the proposed measures.

Piezoelectric structure stands as smart sensors (or actuators) in control systems or high-efficient energy harvesters in powering engineering which have aroused significant interests, and the structural dynamic responses analysis is crucial to avoid unwanted vibrations. This work aims to study the transient thermo electromechanical responses of a two-dimensional orthotropic piezoelectric plate of crystal class mm2 with quadratic temperature-dependent thermal conductivity. The nonlinear governing equations are established based on the L-S piezoelectric thermoelasticity, and thermal conductivity is adopted as the quadratic function of the temperature. To solve the nonlinear solutions, the nonlinear time-domain finite element method is developed to directly solve nonlinear finite element governing equations, of which maximally avoids the precision losses within the applications of the integrated transformation method. Numerical results reveal that quadratic temperature-dependent thermal conductivity remarkably affect nonlinear transient thermo-electromechanical responses, whilst the electrical energy harvesting ability and heat wave propagation in orthotropic piezoelectric plate are maximally lifted.

The lining of water conveyance canals in cold regions is usually subjected to serious damage, such as spalling, bulging, and fracture, due to the harsh natural environment. The main causes of these types of damage are the normal frost-heaving force and tangential frost-heaving force (adfreeze force) acting on the liner plate. In this study, the adfreeze forces between the foundation soil and liner plate were studied using the direct shear test, considering the effects of the initial water content, test temperature, and compactness. The results show that the increase of the water content, the increase of the temperature, and the decrease of the compactness increased the interfacial peak shear displacement, and they all varied in the range of 0.3–1.6 mm. With the decrease of the initial water content of the soil sample, the increase of the test temperature, and the decrease of the compactness, the peak shear stress decreased significantly with the amplitude between 51 and 87%. The interfacial cohesion decreased significantly with the increase of the initial water content, the increase of the temperature, and the decrease of the compactness. The interfacial friction angle had no apparent variation pattern. At room temperature, the interfacial friction angle decreased significantly with the increase of the water content. When the water content was 30%, the interfacial friction angle was almost lost completely, which can easily lead to the sliding loss of the foundation soil and further damage, such as the instability of the lining.

In artificial freezing engineering, the freezing temperature is an important factor affecting soil frost heave deformation, and studying its impact is of great significance. The frost heave ratio of soil is a crucial factor for designing and predicting soil frost heave. However, it only considers vertical deformation while neglecting radial deformation. This paper introduces a simple unidirectional freezing apparatus specifically designed for three-dimensional x-ray computed tomography (CT) scanning, which allows for the investigation of internal structural changes in clay during freezing at four different freezing temperatures (i.e., −3 °C, −5 °C, −7 °C, and −9 °C). Freeze-necking of the soil was observed during freezing. An image processing method was proposed to segment the soil samples, and parameters such as length, equivalent diameter, and volume were measured to assess changes during freezing. The observed variations in necking depth and equivalent diameter indicate that freeze-necking is uniform. As the freezing temperature decreased, the necking depth reduced from 72.4 mm to 38.1 mm, and within this necking depth, the equivalent diameter decreased progressively from the bottom to the top. Moisture content increased near the cold end of the soil and decreased near the warm end, suggesting that freeze-necking is due to moisture migration within the soil. Considering freeze-necking, the volumetric frost heave ratio was defined to characterize soil frost heave deformation. This ratio also decreases as the freezing temperature decreases, and the values are smaller than those of the traditional frost heave ratio. The discrepancies become more pronounced at higher freezing temperatures, reaching up to 1.8% at −3 °C. The results indicate that lower freezing temperatures can reduce frost heave deformation, and freeze-necking requires greater attention in engineering at higher freezing temperature.