Plant roots can significantly enhance the mechanical properties of soils, but accurately predicting the root reinforcement effects remains challenging. This study introduces a novel hypoplastic model for saturated soils reinforced with plant roots, by incorporating root effects into soil mechanical behavior. The model explicitly integrates root reinforcement into the soil constitutive equations by introducing easily obtained parameters, including root area ratio (RAR) and root tensile strength (Tr). To validate the model, two experimental datasets were used: one from this study, involving Cynodon dactylon root-reinforced soil in consolidated undrained triaxial tests, and the other from the literature, which includes data from Cryptomeria D. Don root-reinforced soils in consolidated drained and undrained triaxial tests. A comparison of the model calculations with experimental data showed that the model can accurately predict the stress-strain behavior and volume deformation characteristics of root-reinforced soils with varying root contents and confining pressures. Roots improve soil strength by resisting tensile stresses along shear planes. Furthermore, root reinforcement reduces volumetric compression by limiting soil contraction under stress. The sensitivity analysis indicates that both RAR and Tr significantly influence the mechanical behavior of root-reinforced soils, improving shear strength and reducing deformation, providing valuable insights for geotechnical engineering design. The proposed model offers a reliable theoretical tool for analyzing root-reinforced soils in ecological geotechnical engineering, supporting the advancement of sustainable root reinforcement applications.

Undrained creep behaviors of a clay within the atmospheric influence depth are studied considering the typical low confining pressure and alternate freeze–thaw–drying–wetting (FTDW) effects. Triaxial experimental tests and numerical simulations based on the proposed material point method (MPM) algorithm are conducted to cross-validate and investigate the creep characteristics of a compacted clay after FTDW cycles. The experimental tests focus on the effects of stress states and FTDW cycles on macroscopic axial strain development. After confirming that the simulated deformation property matches the measurements, the variation of microscopic information for solid particles and water particles within specimens is analyzed from numerical simulation. The results indicate that the increase in different components of axial strain is inconsistent under FTDW effects. In particular, the proportion of creep strain rises after FTDW cycles under low-stress states. Microscopic information illustrated by axial displacement field, water pressure evolution, and solid particle spacing variation is influenced by the monitoring position, stress states, and FTDW cycles. Our research provides a comprehensive understanding of the undrained creep behaviors of a compacted clay under FTDW effects.

Trifolium repens L. (T. repens L.), a globally distributed legume, is commonly cultivated along streambanks owing to its broad environmental adaptability. However, the reinforcement mechanism of T. repens L. roots remains insufficiently characterized. This study comprehensively investigated the morphological characteristics of T. repens L. roots concerning soil depth, plant density, and growth stage. The tensile strengths of roots broken simultaneously and progressively (tr and sr), along with flexural strength (fr) were examined. The variation patterns in the shear strength of the T. repens L. root-reinforced soil were also analyzed. Results indicated a decrease in cohesion at the 12-month growth stage, which may be attributed to the changes in soil structure and specimen size in the shear test. Root cohesion (cr) was calculated using classical models, but the models proved inadequate for capturing the complexity. According to existing research, linear functions were employed to model the relationships between cr and tr, cr and sr, as well as cr and fr, respectively. Among these, cr exhibited a stronger correlation with sr. However, these functions remained insufficient for accurate calculations. Considering root bending, an empirical correction model relating cr to sr and fr was proposed and validated, achieving error rates below 15%. This model can calculate cr for T. repens L. root-reinforced soil regardless of variations in plant density and growth stage, but further improvements are still necessary.

Landslide dams, as a special type of earth dams, are characterized by complex geomorphological features and geotechnical properties. The failure of landslide dams induced by seepage should not be overlooked. This study introduces a calculation method for analyzing the slope stability of landslide dams with three different material compositions under seepage conditions. Furthermore, the influence of spatial heterogeneity in particle size on the stability of landslide dam slopes subjected to unsaturated seepage is investigated using the random finite element method combined with Monte Carlo simulation. This paper provides a reference for the reliability evaluation of landslide dams with different material types.

High slopes associated with large hydraulic infrastructures are prone to progressive deformation and instability, posing significant risks to engineering safety. This study presents a field application of distributed optical fiber sensing (DOFS) at a high rock slope of a hydropower project located in Northwest China, where ongoing deformation of a joint intake slope has been observed since 2022. A multi-orientation monitoring system comprising six boreholes (vertical, inclined, and horizontal) instrumented with distributed strain-sensing fibers was deployed to capture internal deformation. The monitoring results reveal time-dependent and depth-localised displacement patterns, with horizontal displacement magnitudes of approximately 1.5–2.0 mm within 2 months and multiple potential slip surfaces identified within a depth range of 20–50 m. The deformation localisation is consistently captured across different borehole orientations, demonstrating the capability of the DOFS system to detect small-scale deformation relative to its spatial resolution (0.255 m). These observations indicate the presence of complex multi-level deformation mechanisms within the slope. The inferred slip surface locations were further validated against independent engineering evidence, including borehole core observations, anchor drilling records, and adit crack mapping, showing strong agreement with zones of fractured and weakened rock mass. The results demonstrate that DOFS provides continuous, high-resolution, and reliable monitoring of internal slope deformation, enabling both slip surface identification and quantitative deformation assessment. This study highlights the significant potential of DOFS for early warning, hazard mitigation, and the design of reinforcement measures in large-scale slope engineering.

The increasing complexity of urban underground engineering has led to limitations in the real-time performance and prediction accuracy of traditional geotechnical parameter acquisition methods. The integration of digital twins and intelligent algorithms provides a new technical path for high-precision parameter inversion. This study constructs a digital twin-driven intelligent geotechnical parameter inversion model. By fusing multi-source monitoring data such as displacement, stress, pore pressure, and vibration, a dynamic inversion framework combining CNN-LSTM and particle swarm optimization is established, and a virtual-real synchronous error feedback mechanism is introduced to achieve online model updates. Experimental results show that the constructed model exhibits high accuracy in complex underground engineering scenarios, with an RMSE reduced to 0.051, a MAE of 0.039, and a determination coefficient R2 reaching 0.982, representing a more than 60% reduction in error compared to the traditional BP model. Under complex strata and strong disturbance conditions, the error decreased by up to 31.6% after dynamic updates, and the prediction stability index remained above 0.917, indicating that this method can effectively improve the accuracy of geotechnical parameter identification and system robustness in complex environments. The research results can provide intelligent parameter identification and risk warning technology support for smart tunnels, deep foundation pits, and underground space engineering.

The consolidation and settlement of soft soil foundations pose significant challenges in geotechnical engineering, where prefabricated vertical drains (PVDs) are commonly used to accelerate consolidation. Accurate prediction of consolidation behaviour is influenced by several factors, including loading patterns, soil layering, and particularly drainage conditions. Traditional analytical and numerical methods often make oversimplified assumptions about drainage conditions, potentially leading to inaccuracies in predicting excess pore water pressure (EPWP) dissipation and settlement. This study presents a novel spectral-based approach for analysing the consolidation behaviour of PVD-assisted multilayered soils subjected to time-dependent loading and general drainage boundary conditions. By using matrix operations, the excess pore water pressure (EPWP) across different soil layers is expressed as a unified solution, which effectively captures the influence of varying drainage conditions. The proposed method is validated through comparisons with laboratory test, field data and some existing solutions, demonstrating improved accuracy and flexibility in predicting EPWP dissipation and settlement. The results highlight the potential overestimation of consolidation when traditional boundary assumptions are applied and underscore the importance of considering more general drainage boundaries, providing practical insights for engineering design and settlement prediction in PVD-assisted foundations.

Global warming and the increasing frequency of extreme heat events pose significant challenges to the stability of vegetation-stabilized slopes. The mechanisms by which temperature variation influences the mechanical properties of root-reinforced soil remain insufficiently understood. This study developed a thermo-mechanically coupled hypoplastic constitutive model that incorporated root reinforcement mechanisms. To comprehensively verify model reliability, temperature-controlled consolidated undrained triaxial tests were conducted on root-reinforced soil. The experimental program considered multiple root contents over a temperature range from 20 to 60 °C. Additional experimental data reported in the literature were also adopted for external validation. Experimental results show pronounced thermal softening at elevated temperatures. The ultimate shear strength at 60 °C decreased by approximately 29.4% compared with 20 °C conditions. Despite this reduction, root reinforcement maintained relatively high absolute soil strength under high-temperature conditions. Comparisons between model predictions and both experimental results from this study and published data demonstrated the reliability of the proposed model. Furthermore, parameter sensitivity analysis revealed that strength enhancement exhibits diminishing marginal gains with increasing root content, indicating the existence of an optimal root content ratio. This study investigates the thermo-mechanical coupling mechanism of root-reinforced soil and provides tools for engineering design under extreme climatic conditions.

Soil cover systems with vegetation can be a potential green alternative for slope stabilization. This study aims to numerically investigate slope stability with three cover systems (one-layer, two-layer capillary barrier, and three-layer with low permeability base) under different rainfall patterns, considering vegetation growth stages and slope angles. The rainfall event with a 100-year return period (597 mm for 24 h) in wet regions is selected, with particular attention to advanced, delayed, and bimodal rainfall distributions. The results show that for bare soil slopes, the three-layer cover system outperforms both one-layer and two-layer covers. The advanced rainfall pattern leads to the fastest decrease in the factor of safety (FOS), reaching a critical state 4.3 h earlier on average compared to other patterns. When a vegetated three-layer cover is present on the slope, young vegetation (3 months) increases the FOS by 146%, while aged vegetation (19 months) maintains a 65% enhancement in FOS and prevents the potential shallow landslide through additional cohesion. For three-layer cover slopes, when the slope angle increases from 30 degrees to 40 degrees, the FOS decreases by an average of 21%. However, the vegetated cover helps maintain the FOS consistently above 1.0. Among all the scenarios considered, the slope with a vegetated three-layer cover demonstrates superior performance in preventing rainfall infiltration and improving slope stability. This study demonstrates that adopting a three-layer cover in slope protection, especially with vegetation, provides an effective solution for rainfall-induced slope failure mitigation.

Frequent earthquakes have significantly exacerbated instabilities in slopes. Accurately evaluating slope stability during seismic events remains a challenging task. In this study, a new method is proposed to evaluate the evolution of seismic stability of a slope based on shear deformation energy calculated by means of shear stress versus shear displacement curve. Shaking table tests are mainly adopted to demonstrate how this proposed method can be used and to validate the feasibility of the method. Seismic acceleration of the slope, soil pressure behind the pile, and displacement of the pile are monitored in shaking table tests. The obtained data on seismic acceleration are used to calculate permanent shear displacement using the Newmark analysis method. By integrating the test data, the evolution of seismic slope stability is analyzed using the proposed method. The results show that the proposed method can be used to calculate the decreasing stability safety factor and to analyze the dynamic change of seismic stability throughout the shear process. This approach offers a quantifiable assessment of slope stability during and after seismic events and thereby provides a scientific foundation for disaster prevention and mitigation strategies.

Freeze-thaw (F-T) cycles in extreme climates alter soil structure, increasing the risk of landslides and shallow slope failures in mountainous regions. In recent years, ecological slope protection using vegetation has attracted growing attention for erosion control. However, the influence of root orientation under F-T conditions remains poorly understood. This study examines the shear strength of root-reinforced soils under different water contents, root orientations of 0 degrees, 45 degrees, 90 degrees, and 135 degrees, and F-T cycle numbers of 1, 3, 5, and 10. The Discrete Element Method (DEM) was used to analyze soil-root interactions at the microscale, visualizing changes in force chains and shear bands. Results indicate that soil shear strength is strongly affected by water content, root orientation, and the number of F-T cycles. High water content reduced the reinforcing effect of roots. Roots inclined at 135 degrees provided the greatest reinforcement, increasing shear strength by 293 % compared to unreinforced soil and maintaining high resistance to F-T damage, with only a 16.1 % strength loss after 10 cycles. F-T processes reduced root cellulose and hemicellulose by 24.8 % and 36.3 %, respectively, weakening tensile strength, while lignin content remained relatively stable. DEM analysis showed that root reinforcement is maximized when roots are oriented perpendicular to the principal stress direction. At 135 degrees, interface root-soil contact forces were 40 % higher than axial forces, confirming this as the main resistance mechanism. These findings enhance understanding of slope stabilization under extreme climatic conditions and highlight the critical role of root orientation in soil reinforcement design.

Consolidation and settlement of soft soil ground are the main problems encountered for geotechnical engineers, and drainage boundary conditions play a crucial role in consolidation analysis and settlement prediction. Despite some theoretical approaches that have been proposed incorporating some particular drainage boundary conditions, there remains a dearth of rigorous analytical solutions for multilayered soils that effectively capture various drainage boundary conditions. This study presents a novel approach where the spectral method is used to capture the impact that drainage boundary condition has on the consolidation of multilayered soil. The drainage boundary condition over time is considered, while the excess pore water pressure (EPWP) profile across different soil layers can be described as a single expression using matrix operations. This proposed method is then verified with field investigations where the varying drainage condition is captured and compared with other solutions. The results show that the consolidation behavior will be overestimated if the traditional boundary conditions are used and the proposed method can predict the consolidation of soil with greater accuracy and flexibility. EPWP and settlement at different depths can be estimated such that they agree better with the field data, and the study also indicates that there is a noticeable discrepancy in the predicted consolidation when the drainage boundary condition is not considered properly.

This study assesses the performance of cut-off walls in a vacuum preloading project at Lianyungang Port, China, to tackle challenges posed by ultra-soft reclaimed land. It investigates the walls' impermeability and structural integrity by analyzing changes in hydraulic conductivity, in-situ lateral displacement, particle size distribution, and dry density both before and after vacuum suction. The introduction of a hydroxypropyl starch-based coupling agent (CA) in slurry reduces the hydraulic conductivity in the sandy matrix. Significant lateral displacement near the surface amplifies the likelihood of cracks, which lead to increased hydraulic conductivity. The cut-off wall is characterized by three zones: an erosion zone with large amount of fine particle mobility, a central effective zone with minimal deformation, and an outer tensile zone whose soil loosening leads to impermeability reduction. These findings provide valuable insights into the design and construction of cut-off walls for similar geotechnical applications and aid in forecasting the performance and lifespan of the cut-off wall.

The inner deformation monitoring of concrete face rockfill dams（CFRDs） is an important way to evaluate their deformation stability and safety. Aiming to overcome the limitations of the traditional monitoring technology in the inner deformation monitoring of high CFRDs, an inner deformation monitoring method based on the distributed optical fiber sensing technology is proposed. Through the application researches on a 200 m-level CFRD, the feasibility of the three optical fiber layout methods（respectively installed in the 45a I-beam, 6-point galvanized steel pipe and protective sand layer） for the horizontal displacement measurement is compared. The results show that the average maximum difference of the measured results of the three optical fiber layout methods is less than 1.0 mm, which verifies the feasibility and consistency of the three optical fiber layout methods. In addition, the calculated results of the three-dimensional FEM analysis and the measured results of the traditional water pipe settler are compared with those by the proposed method. It is shown that the results based on the distributed sensing optical fiber technology are almost consistent with the numerical ones, and the average error between the settlement results and the measured values of the pipe-type settler is less than 10 mm, indicating that the distributed sensing optical fiber technology can meet the inner deformation monitoring requirements of high CFRDs. The rationality and feasibility of the proposed method are verified.

The nonlinear variation of soil compressibility and permeability with void ratio (i.e., e -log σ ′ and e -log k ) has been included in the consolidation theory to accurately predict the behavior of soft soil stabilized by vertical drains. However, most current nonlinear consolidation models incorporating the coupled radial-vertical flow are based on some simplified assumptions, while including some features such as the complex implementation of multilayered computations, time-dependent loading and stress distribution with depth. This study hence introduces a novel approach where the spectral method is used to analyze the nonlinear consolidation behavior of multilayered soil associated with coupled vertical-radial drainage. In addition, time- and depth-dependent stress and soil properties at each soil layer are incorporated into the proposed model. Subsequently, the solution is verified against experimental and field data with comparison to previous analytical solutions. The results show greater accuracy of the proposed method in predicting in-situ soil behavior. A parametric study based on the proposed solution indicates that the ratio between the compression and permeability indices ( ω = C c /C k ) has a great impact on the consolidation rate, i.e., the greater the ω , the smaller the consolidation rate. Increasing the load increment ratio and the absolute difference between unity and ω (i.e., | ω − 1|) can exacerbate prediction error if the conventional simplified methods are used.

The crack initiation and crack damage strengths of rock are the important indexes to evaluate the high stress failure of hard rock. Based on the Hoek triaxial compression tests and acoustic emission tests, a brittle rock-like model material that can characterize the physical and mechanical behaviors of basalt block is used to carry out researches on the deformation and failure characteristics, acoustic emission characteristics, crack initiation and damage stress threshold levels, rock initiation and damage strength characteristics of the model materials. The evolution characteristics of hard and brittle fractures of the model materials are revealed. The crack initiation and crack damage stress thresholds of the model materials are given. The crack initiation and crack damage strength envelopes of the model materials are defined. The initiation and damage strength characteristics of similar materials of basalt brittle are investigated. The research results may provide certain technical support for the early warning and prediction of stress-induced failures such as wall caving, rock-burst or rupture during the excavation of underground cavities in basalt areas.

A series of tests are conducted on the permeability characteristics of sandy gravel with high fines content. It is found that the permeability coefficient of sandy gravel decreases with the increase of the particles less than 5 mm and the relative density. The change of permeability coefficient with the relative density can be described by the semi-logarithmic formula, and the change of permeability coefficient with the content of particles less than 5 mm can be described by the power function. By using the normalization method, the empirical formula is proposed to predict the permeability coefficient of sandy gravel for overburden in Poyang Lake area. The seepage deformation of sandy gravel with high content of particles less than 5 mm is characterized by the soil flow failure or transitional failure. With the increase of the content of particles less than 5 mm and the relative density, the transitional failure turns to the soil flow one.

The scientific and reasonable deformation monitoring of rock and soil masses is an important index for the evaluation of stability and safety of geotechnical engineering. Given full play to the characteristics of distributed optical fiber sensing measurement technology, based on the specially designed optical fiber deformation test devices, a two-dimensional deformation monitoring method based on the distributed optical fiber sensing technology is proposed. The indoor two-dimensional deformation tests of sensing optical fiber under five kinds of horizontal displacement and settlement adjustment conditions and two sets of simulation and verification of the measured internal deformation of rockfill dam project are carried out. The research results show that the absolute errors of horizontal displacement and settlement measured by 40 groups of tests are less than 1 mm under the five kinds of test conditions. The two-dimensional deformation monitoring method has excellent performance. Based on the measured horizontal displacement and settlement data of a 200 m-high rockfill dam, the indoor simulation tests are carried out. The test results are in good agreement with the measured ones in terms of the curve form and measuring value. The 406 m-long measuring section is subjected to quasi-distributed monitoring with the spacing of measuring points of 3.3 m. The settlement measurement error of the measuring points is cm-level, and the horizontal displacement measurement error is mm-level. It is shown that the two-dimensional deformation monitoring method based on the distributed optical fiber sensing technology can meet the needs of deformation monitoring of rock and soil and has good application prospects.

Based on the emergency rescue, the subsequent disposal, and the development and utilization projects of the Hongshiyan Landside Dam in Ludian, Yunnan, China, research has been conducted on key technical issues facing the development and utilization of landside dams, including the possibilty evaluation of development and utilization, structure analysis of wide gradation material, performance evaluation, investigation and design, dam seepage control, construction technology and equipment, and safe operation assessment. And innovative results has made in all seven aspects mentioned above, writing the history in this field. The achievements were directly applied to the development planning, investigation and design, construction, and operation and maintenance of the Hongshiyan Landside Dam, a comprehensive water conservancy project that integrates flood control, water supply, irrigation, and power generation, with significant comprehensive benefits.

In order to ensure the safety of people's lives and properties and the sustainable development of the national social and economic security in China, it is a major trend required by the development of the country and industry to seek advantages and avoid disadvantages when dealing with natural disasters, and to maximize the use of the infinite power of nature to benefit the people while reducing disaster losses. The National Key R & D Program of China "Research and development of guarantee technologies and equipments for dangerous situation disposal and utilization of barrier dams" aims at the challenges of the major scientific and technological problems, and multiple levels of work are carried out in this research program, such as mechanism disclosure, basic theory, equipment development, technology integration, application studies and application demonstration. The innovative achievements with industrial characteristics in the new era have been made in terms of the evolution process of dangerous situations of barrier dams, the evolution mechanism of long-term working behaviors, the development and utilization theory and the comprehensive treatment technologies. The important theoretical basis and advanced technical support can be provided for the disposal of barrier dam hazards, the construction of development and utilization projects and the long-term safe operation. The research achievements ensure that the development and utilization of the barrier dams can fully play the role of eliminating dangers of flood control disasters in the upstream and downstream of the barrier lakes, improving the local water supply and irrigation conditions, eliminating harm and promoting profits, with significant social and economic benefits.