The fractures make the thermal-hydro-mechanical(THM) characteristics of rock mass and soil mass obviously different，and the existing frozen soil theory is difficult to solve the freeze-thaw disaster problem of low temperature rock mass. The migration mechanism of fracture water，the heat transfer mechanism of fracture，the dynamic evolution of fracture characteristics and the multi-field coupling of thermal-hydro-mechanical in heterogeneous rock mass are the key to study the freeze-thaw disaster of low-temperature rock mass. In this paper，the research progress of low-temperature rock mass with phase change is analyzed from four aspects： water migration mechanism，heat and mass transport characteristics，physical and mechanical characteristics and THM coupling characteristics. The research results on low-temperature rock mass at home and abroad are abundant，but the heterogeneity caused by fractures and the special characteristics of the THM properties of fractures under the condition of phase change are not fully considered. The mechanism of hydrothermal migration in fracture of low-temperature rock mass has not been proved，and there is lack of large-scale test equipment for studying the THM characteristics of low-temperature fractured rock mass. Although the fracture propagation caused by frost heave has been studied，the dynamic fracture evolution equation considering the whole process of freeze-thaw and the freeze-thaw cycle has not been established. The freeze-thaw disaster of low-temperature rock mass involves hydrothermal migration at the micro-level，fracture evolution at the meso-level and deformation and failure at the macro-level. So far，no THM coupling model has been established which integrates the results of micro-meso- macro. In order to explore the THM characteristics of low-temperature rock mass，the ice-water phase should be taken as the breakthrough point，the discontinuous characteristics caused by fractures should be closely linked，large-scale laboratory equipment should be developed，the mechanism of hydrothermal migration in fractures should be verified，the fracture evolution equation should be derived，the THM coupling model should be constructed，and numerical simulation programs should be developed，to finally realize the simulation of freeze-thaw disasters in low-temperature rock mass.

The shear support performance of 2G-NPR bolts has been verified; however，their damage behavior under fatigue loading remains to be further explored. Through laboratory pre-peak cyclic loading tests，the shear mechanical properties of PR steel(Q235 steel) and 2G-NPR steel bolted rock joints were compared，exploring the effects of different normal stresses，roughness，shear amplitudes，and rates on the shear fatigue damage characteristics of 2G-NPR steel bolted rock joints. The results show that：(1) As the normal stress increases，the shear strength of PR steel bolted rock joints exhibits a marked decrease after an initial increase in the number of cycles，whereas the shear strength of 2G-NPR steel bolted rock joints gradually increases. This trend underscores the significant role of the negative Poisson?s ratio effect in enhancing the shear fatigue performance of the 2G-NPR steel bolts. (2) The peak and residual shear strengths of 2G-NPR steel bolted rock joints significantly increase with higher shear rates and normal stresses，but are less affected by changes in joint surface roughness and shear amplitude. Additionally，the pre-peak shear stiffness of these joints increases with roughness，shear rate，and normal stress，while shear amplitude has only a minor effect. The flexural angle of the anchor rod increases with the roughness，shear amplitude，and shear rate. (3) The ratio of shear force to axial force of 2G-NPR anchor bolts is consistently lower than that of PR anchor bolts under different cyclic loading conditions，indicating that the 2G-NPR bolts can effectively withstand axial force during shear deformation，thus maintaining the stability and support effectiveness of the rock mass. This research offers a valuable reference for the application of 2G-NPR anchor bolts in rock mass support engineering，particularly in regions prone to microseismic activity.

Due to the small thickness of the laminae，traditional experimental methods such as single triaxial based on standard cylindrical samples are difficult to respond to the effect of strong inhomogeneity of the laminated shale on the mechanical properties. In this paper，the laminated shale of the Qingshankou Formation was selected to conduct scratch and CO2 soaking experiments，and the softening pattern of different laminated strengths under different immersion times was analyzed. The results reveal that as the soaking time increases，induced cracks form around the scratched area，with the shape of a“Y”. Supercritical CO2-water had the most significant effect on calcite-rich lamina. Compared with the original shale specimens，the compressive strength decreased by 48.1%，57.3%，and 60.3%，and the elasticity modulus decreased by 39.3%，49.2% and 50.5%，respectively，with the increase of the soaking time(1，2，3 d). The compressive strength and elasticity modulus of the clay-rich lamina first showed a rapid decreasing trend with increasing soaking time and then remained constant. The compressive strength and elastic modulus of the quartz/calcite lamina first decreased and then slightly increased. This study provides a new perspective on the softening behavior of shale under supercritical CO2-water interaction.

Accurate identification of sandification grades is crucial fordisaster prevention and control in sandy dolomite tunnels. However，the existing sandification grade classification methods cannot be effectively combined with advanced geological prediction，which weakens the role of advanced horizontal drilling results in disaster prevention and control to a certain extent. Based on the analysis of disaster cases，the rock breaking of bit numerical simulation under six typical working conditions was conducted by the ABAQUS. The drilling results of the corresponding rock strata were analyzed from two aspects of drilling displacement and real-time drilling speed，and the field drilling test was carried out. The frequency distribution characteristics of the drilling speed of the surrounding rock with different sandification grades were analyzed. Furthermore，a prediction model of sandification grade based on drilling speed was constructed and verified. The results show that：(1) The drilling speed of sandy dolomite increases with the increase of sandification grade，and it is reasonable and feasible to use drilling speed as a prediction index of dolomite sandification grade. (2) Based on the statistical analysis of 434 groups of actual advanced horizontal drilling speed，the likelihood of drilling speed in the range of 2.33–5 mm/s in weak sandy dolomite is 92.47%，the possibility of drilling speed in the range of 3.33–6.67 mm/s in severe sandy dolomite is 87.18%，and the possibility of drilling speed in the range of 4.17–9.17 mm/s in complete sandy dolomite is 90.74%，all of which show normal distribution. (3) The prediction model of sandification grade is applied to the Water Diversion Project in Central Yunnan，and the identification results are consistent with the actual sandification grade. The research results directly promote the application of advanced horizontal drilling results to the prediction and identification of sandification grade and guide the disaster prevention and control of sandy dolomite tunnels.

Landslide sample data is the basis of susceptibility modeling construction，the lack of landslide samples will affect the accuracy of susceptibility modeling and prediction results. In order to reveal the susceptibility law under the different landslide samples missing conditions and propose a potential landslide identification method，the Xunwu County in Jiangxi Province is selected as the case study. The landslide catalog data by field geological survey is assumed as the basic ideal landslide samples condition. And the different landslide sample missing conditions are determined by randomly and evenly selecting and eliminating landslide samples with different proportions of 10%，20%，30%，40% and 50%. Meanwhile，the landslide sample aggregation missing condition is determined by eliminating the landslide samples in the southern part of the study area. Then，the random forest and support vector machine models are selected to construct landslide susceptibility models under different landslide sample missing conditions，and the effect of landslide sample missing conditions on landslide susceptibility prediction is analyzed. Additionally，the Susceptibility-InSAR method has been proposed by combining SBAS-InSAR technology and landslide susceptibility prediction results to identify potential landslides. Finally，based on the landslide sample aggregation missing condition，the potential landslides are used as expanded landslide samples to reconstruct the landslide susceptibility model and to evaluate the performance accuracy. The results show that：(1) the larger the proportion of landslide sample missing data，the stronger the uncertainty of the landslide susceptibility prediction results，and the landslide susceptibility prediction accuracy in landslide sample aggregation missing condition decreases significantly. (2) The Susceptibility-InSAR multi-source information method can accurately identify potential landslides，providing an effective method for expanding landslide samples in areas with missing landslide data. (3) Compared with the landslide sample aggregation missing condition，the landslide susceptibility results in the condition of expanding landslide samples have higher precision and lower uncertainty，suggesting that potential landslide identification can effectively mitigate the significant issue of landslide sample aggregation missing condition.

Recent advancements in the automatic extraction of slope units have been significant. However，research on the effective organization of landslide hazard data based on slope units remains limited，particularly regarding the impact of slope unit scales and landslide sampling methods on regional landslide susceptibility assessments. This study focuses on the Yuqu River Basin in southeastern Tibet，where six slope unit scales，ranging from fine to coarse，were defined by adjusting slope unit size parameters. Additionally，three landslide sampling methods-centroid-based，intersecting centroid-based，and area ratio threshold-based—were developed using landslide vector points and polygons. These approaches enabled the construction of 33 distinct datasets for evaluating landslide susceptibility. The results indicate that fine-scale slope units struggle to achieve high predictive accuracy，while overly coarse units reduce the rationality of susceptibility zoning，particularly through the overestimation of high-susceptibility areas. A moderate slope unit size can enhance the model?s predictive accuracy，leading to more reasonable partitioning results. This finding also validates the effectiveness of the principle of maximizing internal homogeneity and external heterogeneity of topography in landslide susceptibility assessments，providing robust support for the appropriate selection of slope unit sizes. Moreover，under complex environmental conditions，assigning the slope unit containing the landslide centroid as the sample proves to be a robust and rational method，enhancing both the predictive accuracy and zoning performance of the model. The variations in susceptibility assessment outcomes across different data organization strategies are primarily due to the effectiveness of the correlation between landslides and environmental factors，especially the distinctiveness between landslide and non-landslide scenarios. This study provides a valuable reference for landslide susceptibility modeling based on slope units in the alpine canyon regions of southeastern Tibet and significantly contributes to improving the quality of landslide risk assessments in complex environments.

In order to investigate the failure characteristics of fissured sandstone subjected to combined dynamic and static stress states，the true triaxial rockburst test system(QKX-YB200)，acoustic emission monitoring system and camera were used to conduct true triaxial unloading and dynamic disturbance tests on red sandstone under different fissure inclinations ，initial static stresses and dynamic disturbance conditions(disturbance directions，disturbance amplitudes and disturbance frequencies f ). The results indicate that：(1) The failure mode of fissured sandstone is tensile with shear failure under true triaxial unloading and dynamic disturbance condition，while the proportion of tension cracks and shear cracks varies depending on different influencing factors. (2) For the specimens that have undergone instability failure，the wing crack propagation at the tips of the fissure transforms from single wing cracks or a combination of wing and anti-wing cracks at  ＜90° to single anti-wing cracks at  = 90°. (3) The fractal dimension and the failure severity of the sandstone both exhibit a trend of first decreasing and then increasing with the increase in  . Additionally，these properties are positively correlated with and ，but negatively correlated with f. When the dynamic disturbance shifts from the direction of the maximum principal stress to the direction of the intermediate principal stress，the overall instability failure of sandstone do not occur. (4) The wing crack propagation model of fissured sandstone under true triaxial unloading and dynamic disturbance condition was established. Additionally，the mechanism of wing crack propagation was investigated in relation to the duration of dynamic disturbance and the internal stress environment of sandstone. (5) By investigating the entire energy evolution process of fissured sandstone under true triaxial unloading and dynamic disturbance，the energy condition of triggering rockburst has been summarized. Additionally，the quantitative contributions of various influencing factors to the rockburst hazards on fissured sandstone were analyzed. The study is expected to provide theoretical guidance for the stability evaluation and disaster prevention of deep fissured hard rock in mining operations.

To explore the permeability distribution of overlying strata based on the mining-induced stress relief boundary model in inclined coal seams. With surface subsidence and the stress distribution characteristics of coal walls of the goaf as the medium，based on the correspondence between surface subsidence and overlying strata，then combined with the definition of stress relief boundary，the distribution characteristics of overlying strata relief boundary at different dip angles were determined by theoretical derivation. In addition，the permeability spatial distribution law is obtained through 3DEC numerical simulation and Python secondary development. The results show that with the increase of the coal seam dip angle from 0°to 30°，the stress difference between two sides of the coal walls increases from 0 MPa to 13.1 MPa，and the stress relief region increases from the original 38.4 m to 54.5 m in higher side of the goaf. The stress concentration position shifted by 0.4 m in lower side of the goaf，thus，the stress relief boundary of lower side expanded. While the stress recovery position moved to the low side by 28.3 m in the central goaf，thus，stress relief boundary of goaf moved downward，and the maximum permeability increased from 90 mD to 270 mD in overlying strata. The stress relief boundary model can describe the stress relief degree and the corresponding spatial distribution of permeability well in overlying strata，which provides a reference for the accurate dominant gas drainage area identification.

An accurate field description of fracture flow still presents a huge obstacle in flow mechanics. Unlike some classic flow models，i.e. parallel plate flow，focusing on the velocity distribution along the longitudinal section of the fracture，very little attention is paid to the velocity distribution within the fracture cross-section. The spatial distribution of fracture aperture indicates a geometric field，which significantly impacts the flow velocity distribution within the cross-section，while lacking proper correlation models induces a difficult understanding of statistical analysis of geometric field?s effect on fracture flow distribution. To solve the challenge of carrying out a seepage test with relative compression or shear displacement exceeding 5% in lab，the Reynolds equation-based discrete solution of fracture flow considering the large shear-compression displacements for Beishan granite is made，and through the gradient of seepage rate and velocity divergence，the differential characterization of the seepage field's field function was achieved. For the same group of cracks，three fields of flow velocity，gradient and divergence presents a consistent spatial geometric distribution under different shear or compression displacements and nearly all fields conform to the normal distribution. In addition，with the increase in closed aperture and contact area，the full-scale fracture flow turns into local-scale flow and two vector operators of gradient and divergence describing the evolutional distribution of fracture flow are still effective. The results show that in the statistical sense，under low-permeability conditions，a rough fracture flow，characterized by the average gradient and the average divergence of the flow velocity field tend towards 0，can be equivalently treated as uniform flat plate flow with low velocity.

As a typical contour blasting technique，presplitting blasting is widely used in rock engineering excavation for foundation pits，highway slopes，open-pit and underground mines. Due to the influence of in-situ stress，deep presplitting blasting requires small-diameter fully coupled charges and closely spaced holes，which affects construction timelines and significantly increases costs. This study aims to investigate the correlation between optimal hole spacing and radial decoupling coefficients under high in-situ stress through theoretical derivation and numerical analysis. A double-hole presplitting blasting model is established using linear elastic theory，incorporating the stress wave superposition effect. This model determines the optimal relationship curves for hole spacing and radial decoupling coefficients under different high in-situ stresses. Using the self-developed OpenFDEM software，simulations are conducted to assess the expansion of the blasting fragmentation zone and fracture zone under various stress conditions and radial decoupling charges. The results indicate that the stress wave superposition effect promotes crack penetration. At low stress conditions，a lower decoupling coefficient significantly enhances crack extension. However，it also increases the density and extent of fracture branching. This enlarges the damage zone and hinders the formation of pre-splitting cracks. As in-situ stress increases，the influence of the stress wave superposition effect diminishes. This further affects the pre-splitting cracks formation in double-hole blasting. This paper proposes optimal hole spacing values that fully consider the interaction between high in-situ stress and stress wave superposition effects，providing important references for enhancing pre-splitting cracks formation in double-hole blasting.

The stability control of surrounding rock is crucial when the submarine tunnel passes through poor geological conditions like fault fracture zone. In this paper，a numerical analysis method of surrounding rock stability is proposed，which requires the stability of the surrounding rock in the whole area of the tunnel to be calculated first，and then the refined hazard process of high-risk area is analyzed. Numerical simulation with FLAC3D and DEM methods are carried out respectively based on the F9 fault and weathering trough section of the Shantou Bay Submarine Tunnel Project. The high-risk sections of the tunnel were evaluated. The control effect of different grouting reinforcement area thicknesses on the deformation of the tunnel surrounding rock was compared by simulation. Based on the comparison results，a scheme of joint grouting on the sea surface and inside the tunnel was proposed. The reliability of the proposed scheme was verified through numerical simulations and measurements of Shantou Bay Tunnel. The implementation of the grouting scheme ensured the safety of tunnel construction. The relevant conclusions offer valuable insights for controlling the stability of surrounding rock and optimizing grouting schemes during the construction of submarine tunnels under similar conditions.

In the construction process of the landslide displacement prediction model，in order to clearly separate the landslide displacement parts affected by various features to enhance the mechanical interpretability and generalization ability of the displacement prediction model，a step-type landslide displacement prediction model based on the influence of creep trend and feature optimization algorithm is proposed. Firstly，the Particle Swarm Optimization-Based Variational Modality Decomposition(PSO-VMD) Method is used to decompose the training data into other data curves and trend displacement with influence of Nishihara creep model. Secondly，the external influence features of landslide displacement are comprehensively selected，other data curves are separated and reconstructed with the genetic feature optimization algorithm(GA) to obtain the fluctuation displacement with Fourier characteristics and the influence displacement that maximizes the correlation with external influence features. The Nishihara creep Taylor expansion polynomial model，Fourier function model and Convolutional Neural Network-Squeeze Excitation Attention Module-Gated Recurrent Unit Model(CNN-SE-GRU) are used to respectively fit and predict the trend displacement，fluctuation displacement and influence displacement. The errors of each displacement model training fit are defined as the random displacement；it is predicted by the Gray Wolf Optimization-Based Extreme Learning Machines model under the constraint of kernel density estimation(KDE-GWO-ELM). Finally，the prediction of step-type landslide displacement is accomplished by superimposing all displacement prediction model results. Taking the step-type landslide- namely Baishuihe landslide as an example，the cumulative horizontal displacement data of monitoring points ZG118 and ZG93 from November 2005 to October 2009 are selected as training data，and the data from November 2009 to July 2010 are selected as prediction data for research. The prediction results show that the root mean square error(RMSE) of monitoring points ZG118 and ZG93 under the prediction model 5.85 mm and 10.61mm respectively，the mean absolute percentage error(MAPE) are 0.27% and 0.43% respectively. Compared with the CNN-SE-GRU/LSTM model，GWO-ELM model，VMD-GWO-ELM model and EEMD-CNN-GRU model，the novel prediction model not only improves the prediction accuracy，but also shows clearly the influence of time features，external influence features and error features for prediction model. Thus，it has excellent interpretability and generalization ability.

The development of reclaimed islands and reefs has emerged as an important strategic measure for coastal nations. This paper systematically investigates the mechanical properties and engineering characteristics of coral-reef limestone in the proposed area for Male-Airport Island cross-sea bridge project. Based on the results of static load tests and core drilling conducted on post-grouted rock-socketed drilled shafts，this study provides a comprehensive analysis of the bearing deformation characteristics of the shaft embedded in coral-reef limestone before and after grouting. Additionally，the integrity of the shaft and the permeation diffusion range of the grouting are thoroughly evaluated. The test results reveal that the coral-reef limestone exhibits notable characteristics，including low density，large pore sizes，unique structure，strength anisotropy，and uneven cementation. Furthermore，large-diameter post-grouted rock-socketed drilled shafts demonstrate promising application potential in the coral-reef limestone strata. The post-grouting technique enhances the bearing deformation capacity of shaft foundations in coral-reef limestone，with the ultimate bearing capacity of the test shaft increasing by 3.6% after grouting，and the displacement of the shaft head decreasing by 33.53% compared to before grouting. Core drilling tests indicate that the grouting at the shaft tip penetrates approximately 3 m(around 2D) downward，which significantly improves the pore structure of the coral-reef limestone. Finally，by correlating the unconfined compressive strength of intact coral-reef limestone with the ultimate side resistance and tip resistance，this paper develops a computational method for calculating the load capacity of grouted rock-socketed drilled shafts in coral-reef limestone formations. This methodology offers a robust scientific foundation and theoretical basis to guide subsequent engineering applications.

Clarifying the blasting vibration characteristics in soil-rock strata is a critical prerequisite for controlling the effects of blast-induced vibrations. Based on an underground blasting project in a typical urban soil-rock stratum，a model test of horizontal-hole blasting in soil-rock strata was designed and conducted. Combined with finite element numerical methods，the influence of the blasting source and site conditions on the propagation laws of blast-induced vibrations in soil-rock strata was analyzed. Finally，a predictive model for blasting vibration in soil-rock strata was established based on dimensional analysis. The results show that the soil-rock interface exhibits high-frequency filtering characteristics，while the free surface shows a vibration amplification effect. The R-wave develops in the direction away from the epicenter，resulting in a segmented attenuation characteristic of the vibration velocity at the free surface. Increasing the burial depth of the blasting source suppresses the attenuation of vibration velocity across discontinuities，weakening energy dissipation at the soil-rock interface and site amplification effects. Increasing the wave impedance ratio of the rock and soil slows down the attenuation of vibration velocity at the soil-rock interface，while accelerating energy dissipation at the interface and vibration velocity attenuation at the free surface，thus enhancing site amplification effects. Increasing the soil thickness does not affect the vibration characteristics at the soil-rock interface but promotes vibration velocity attenuation at the free surface，suppressing site amplification effects. Under small-angle assumptions，the dip angle of the soil-rock interface almost does not affect site vibration. The constructed blasting vibration prediction model considers the site characteristics of soil-rock strata，providing a theoretical basis for blasting vibration control in such conditions.

To explore the influence of organic matter content in the basement soil of open-pit coal mines on its mechanical properties，this study focuses on the Yimin open-pit coal mine in Inner Mongolia. Various tests，including bounded water content，unconfined compressive strength，direct shear，repeated shear，penetration，and SEM，were conducted on dump basement soil samples with different organic matter contents. The effects on mechanical properties，permeability，and microstructure were analyzed at both macroscopic and microscopic scales. Results indicate that the plasticity index is positively correlated with organic matter content. The peak unconfined compressive strength increases with higher organic matter，changing the failure mode from plastic to brittle. Peak shear strength also rises linearly with organic matter content，more prominently under high consolidation stress. As organic matter content increases，cohesion increases while the internal friction angle decreases. Under various normal consolidation stresses，the shear strength of plain soil samples significantly decreases after three shear cycles (16.88% to 21.24%). Adding organic matter significantly reduces the shear strength attenuation rate(2.17% to 7.25%)，which remains stable as organic matter content further increases. The permeability coefficient decreases sharply from plain soil to 5% organic matter content，significantly affected by the presence of organic matter. SEM analysis shows soil particles evolving from point-to-point and point-to-surface contact to face-to-surface contact with increasing organic matter，filling pores and making soil denser. Quantitative analysis using PCAS software reveals that microscopic porosity，fractal dimension of porosity，orientation probability entropy，and fractal dimension increase with organic matter content，while the average pore shape coefficient initially increases then decreases，peaking at 15% organic matter.

The shallow seabed in China's offshore wind farms is primarily composed of soft clay that can exhibit remarkable cyclic softening and deformation accumulation. Accordingly，suction caisson foundations and the supported superstructure can show excessive displacement accumulation under seismic loading，and thus threatening serviceability of wind turbine. This works conducts centrifuge shaking table tests for turbine supported by single caisson and multi-caisson jacket foundations in undrained clays，and constructs corresponding numerical model based on an undrained total stress-based constitutive model for cyclic loaded clay accounting for small-strain stiffness. The numerical model was validated against experimental data. By using numerical simulations，this work studies the effects of foundation types on the acceleration and deformation response of wind turbine superstructure under seismic loading. The relationships between turbine seismic response and filtering frequency-contents of earthquake loading via foundations are explored. This study shows that the proposed numerical model can reasonably capture the seismic response of suction caisson foundation and superstructure. There are strong correlations between magnitude of turbine tower accumulative displacement and its vibration intensity during earthquake. When featuring similar static loading characteristics，compared to single-caisson foundation，multi-caisson jacket can filter certain higher-order frequencies of seismic loading，and thus leading to smaller superstructure acceleration and consequently lower cumulative displacements.