Despite extensive research on slope seepage mechanisms, a reliable long-term prediction method for slope deformation considering rainfall remains undeveloped, largely due to the complexity of rainfall-induced slope instability. This study leverages a project in slope engineering to explore slope deformation under heavy rainfall using intelligent monitoring techniques and genetic algorithm (GA) optimization for neural network prediction. By analyzing slope deformation patterns under varied rainfall intensities, results reveal that limited rainfall has minimal impact on slope stability, whereas excessive rainfall disrupts internal seepage patterns, increasing pore water pressure and reducing soil shear strength, it thereby enhances the risk of slope instability and potential landslides, significantly impacting slope stability. The GA-optimized network accurately captures abrupt slope deformation stages, avoids local optima, and provides a viable framework for early warning of slope instability.

Nearly 1 100 fissures have formed on the Hebei Plain in China. Within the Yellow River-Qinghe River-Zhanghe River shallow buried paleochannel band on the plain, 93 ground fissures controlled by paleochannels have developed, of which the Wuyi-Fuping ground fissure is a typical paleochannel-controlled fissure located in Hengshui, Hebei Province, with a total length of 3 km, a dominant strike of NE78 degrees, and nearly upright in the shallow layer. The surface damage observed in this fissure primarily manifests as beaded pits, and its activity shows distinct segmentation characteristics. On the trench profiles, the offset distance of shallow layers remains consistently around 20 cm within the depth range of 0 to -3 m. An evident flexure is observed in the strata at depths ranging from -4.5 to -7 m. The drilling profile reveals that there is an absence of dislocations in the deeper strata. Nonetheless, the shallow seismic physical profiles unveil the presence of underlying faults beneath the study area, underscoring the intricate formation process and genesis mechanism of the Wuyi-Fuping ground fissure. Firstly, the formation and evolution of the Qingling River's paleochannel were shaped by the actions of fault blocks and underlying faults. The interplay of the regional stress field, fault block movement, and fault activity played pivotal roles in driving the development of this paleochannel. Secondly, the paleochannel exerts a controlling influence on the development location and severity of the fissure. During pumping, the confined aquifer within the paleochannel undergoes water loss and compression, resulting in the formation of a surface subsidence funnel. When the tensile stress surpasses the soil's tensile strength at the funnel's edge, the soil fractures give rise to a ground fissure. Finally, large amounts of surface water generated by heavy rainfall and irrigation can cause existing hidden ground fissures to rupture, emerge, and expand. This paper provides a heretofore generally unknown example, promotes research on the mechanisms of paleochannel-controlled fissures, and has guiding significance for disaster prevention and reduction in this area.

Affected by global warming, permafrost thawing in Northeast China promotes issues including highway subgrade instability and settlement. The traditional design concept based on protecting permafrost is unsuitable for regional highway construction. Based on the design concept of allowing permafrost thawing and the thermodynamic characteristics of a block-stone layer structure, a new subgrade structure using a large block-stone layer to replace the permafrost layer in a foundation is proposed and has successfully been practiced in the Walagan-Xilinji of the Beijing-Mohe Highway to reduce subgrade settlement. To compare and study the improvement in the new structure on the subgrade stability, a coupling model of liquid water, vapor, heat and deformation is proposed to simulate the hydrothermal variation and deformation mechanism of different structures within 20 years of highway completion. The results show that the proposed block-stone structure can effectively reduce the permafrost degradation rate and liquid water content in the active layer to improve subgrade deformation. During the freezing period, when the water in the active layer under the subgrade slope and natural ground surface refreezes, two types of freezing forms, scattered ice crystals and continuous ice lenses, will form, which have different retardation coefficients for hydrothermal migration. These forms are discussed separately, and the subgrade deformation is corrected. From 2019 to 2039, the maximum cumulative settlement and the maximum transverse deformation of the replacement block-stone, breccia and gravel subgrades are -0.211 cm and +0.111 cm, -23.467 cm and -1.209 cm, and -33.793 cm and -2.207 cm, respectively. The replacement block-stone subgrade structure can not only reduce the cumulative settlement and frost heave but also reduce the transverse deformation and longitudinal cracks to effectively improve subgrade stability. However, both the vertical deformation and transverse deformation of the other two subgrades are too large, and the embankment fill layer will undergo transverse deformation in the opposite direction, which will cause sliding failure to the subgrades. Therefore, these two subgrade structures cannot be used in permafrost regions. The research results provide a reference for solving the settlement and deformation problems of subgrades in degraded permafrost regions and contribute to the development and application of complex numerical models related to water, heat and deformation in cold regions.