The frequent occurrence of earthquakes worldwide has rendered highway slope protection projects highly vulnerable to damage from seismic events and their secondary disasters. This severely hampers the smooth implementation of post-disaster rescue and recovery efforts. To address this challenge, this study proposes a comprehensive method for assessing seismic losses in slope protection projects, incorporating factors such as topography and elevation to enhance its universality. The method categorizes seismic losses into two main components: damage to protection structures and costs associated with landslide and rockfall clearance and transportation. This study estimates the cost range for common protection structures and clearance methods under general conditions based on widely recognized quota data in China. It establishes criteria for classifying the damage states of protection structures and provides loss ratio values based on real-world seismic examples and expert experience, constructing a model for assessing damage losses. Additionally, by summarizing the geometric characteristics of soil and rock accumulations on road surfaces, a method for estimating landslide volumes is proposed, considering the dynamic impact of slope gradients on clearance and transportation volumes, and a corresponding cost assessment model for clearance and transportation is developed. The feasibility and reliability of the proposed method are verified through two case studies. The results demonstrate that the method is easy to implement and provides a scientific basis for improving relevant standards and practices. It also offers an efficient and scientific tool for loss assessment to industry practitioners.

In unsaturated soil mechanics, the liquid bridge force is a significant source of soil cohesion and tensile strength. However, the classical Young-Laplace equation, which neglects the stratified nature of water at the nanoscale, fails to accurately capture the physical and mechanical behaviour of nanoscale liquid bridges. This study utilizes molecular dynamics simulations to investigate the wetting behaviour and mechanical mechanisms of liquid bridges between particles at the nanoscale. The study proposes dividing the liquid bridge force into three components: surface tension, matric suction, and adsorption force, to explain the mechanics of nanoscale liquid bridges more comprehensively. The results demonstrate that water layers within liquid bridges exhibit discrete stratified structures at the nanoscale. Moreover, the mechanical behaviour of liquid bridges is highly dependent on pore water volume and pore spacing. Specifically, the contact angle is positively correlated with the pore spacing, while the liquid bridge force increases with the pore water volume and is inversely proportional to the pore spacing. As the separation distance increases, the liquid bridge force gradually diminishes until rupture occurs. This research expands the applicability of the classical Young-Laplace equation and offers new insights into the mechanical properties of unsaturated soils, particularly clays.

Debris flows are a type of natural disaster induced by vegetation-water-soil coupling under external dynamic conditions. Research on the mechanism by which underground plant roots affect the initiation of gulley debris flows is currently limited. To explore this mechanism, we designed 14 groups of controlled field-based simulation experiments. Through monitoring, analysis, calculation, and simulation of the changes in physical parameters, such as volumetric water content, pore-water pressure, and matric suction, during the debris flow initiation process, we revealed that underground plant roots change the pore structure of soil masses. This affects the response time of pore-water pressure to volumetric water content, as well as hydrological processes within soil masses before the initiation of gully debris flows. Underground plant roots increase the peak volumetric water content of rock and soil masses, reduce the rates of increase of volumetric water content and pore-water pressure, and increase the dissipation rate of pore-water pressure. Our results clarify the influence of underground roots on the initiation of gulley debris flows, and also provide support for the initiation warning of gully debris flow. When the peak value of stable volumetric water content is taken as the early warning value, the early warning time of soil with underground plant roots is delayed by 534 to 1253 s. When the stable peak value of pore-water pressure is taken as the early warning value, the early warning time of soil with underground plant roots is delayed by 193 to 1082 s. This study provides a basis for disaster prevention and early warning of gully debris flows in GLP, and also provides ideas and theoretical basis under different vegetation-cover conditions area similar to GLP.

The entrance of permafrost tunnels in cold regions is particularly vulnerable to frost damage caused by complex thermal-hydro-mechanical (THM) interactions in unsaturated frozen soils. The effects of temperaturedependent volumetric strain variations across different stratum materials on heat and moisture transport are often neglected in existing THM coupling models. In this study, a novel THM coupled model for unsaturated frozen soil integrating volumetric strain correction is proposed, which addresses bidirectional interactions between thermal-hydraulic processes and mechanical responses. The model was validated through laboratory experiments and subsequently applied to the analysis of the Yuximolegai Tunnel. The results indicate that distinct layered ice-water distribution patterns are formed in shallow permafrost under freeze-thaw cycles, driven by bidirectional freezing and water migration. Critical mechanical responses were observed, including a shift in maximum principal stress from the invert (1.40 MPa, frozen state) to the crown (5.76 MPa, thawed state), and periodic lining displacements (crown > invert > sidewalls). Frost damage risks are further quantified by the spatial-temporal zoning of ice-water content-sensitive regions. These findings advance unsaturated frozen soil modeling and provide theoretical guidance for frost-resistant tunnel design in cold regions.

Evaluating the stability of coral islands and reefs in dynamic marine environments, such as waves, tsunamis, storm surges, and earthquakes, is a critical scientific issue in the field of marine geotechnical engineering. Nansha coral sand was used as the study object, and stress-controlled drained and undrained cyclic-loading tests were conducted. The undrained excess pore-water pressure and the drained cumulative volumetric strain of saturated coral sand were determined at various non-plastic fine contents (FC), relative density (D-r), and cyclic stress ratio (CSR). The results indicated that cumulative volumetric strain (epsilon(vp)) developed in coral sand via two modes: cyclic stabilisation and cyclic creep. Analyses revealed that when the potential damage coefficient (DP) x CSR 0.05, epsilon(vp) transitioned into the cyclic creep mode. Utilising cumulative dissipation energy as a linking factor showed an arctangent function relationship between the excess pore water pressure ratio (R-u) and epsilon(vp) values of saturated coral sand with different FC, D-r, and CSR. This relationship was applicable to both stress- and strain-controlled cyclic-loading tests. Parameters m and n of the R-u-epsilon(vp) function model increased with an increasing CSR. Additionally, an increase in the D-r or FC resulted in a decrease in m and an increase in n. Multiple regression analysis further revealed that model parameters corrected for compactness and cyclic stress levels exhibited distinct trends as the void ratio (e) increased. Specifically, CSR alpha x m(D)(R) decreased, and CSR1-alpha x n(D)(R) increased. Both parameters displayed a single power function relationship with e. Based on these findings, a coupled incremental model for the cyclic pore pressure and volumetric strain of saturated coral sand, based on energy conversion, was developed.

Cyclic spherical stresses are prevalent in dynamic stress fields and significantly influence the dynamic behavior of loess, a material characterized by high compressibility and anisotropy. Previous research has primarily focused on shear stresses, often overlooking the impact of spherical stresses. This study investigated the deformation induced by cyclic spherical stress under different initial states. Irreversible and reversible components were identified from both volumetric and shear strains, and their variation patterns were analyzed. Shear strain is found to be generated by the material's anisotropy. The results indicate that the volume of the sample shrinks significantly under cyclic spherical stress, with irreversible volumetric strain increasing nonlinearly as the number of cycles increases. Irreversible shear strains can be categorized into two types based on their formation mechanisms. The first is when significant initial anisotropy leads to radial deformation greater than axial deformation under spherical stress, resulting in shear strain increasing in the negative direction. As consolidation stress increases, the initial anisotropy gradually diminishes. The second is when stress-induced anisotropy results in positive shear strain because consolidation deviatoric stress contributes to an increase in shear strain in the positive direction. As the stress ratio rises, the induced anisotropy is further enhanced. The axial reversible strain of the sample is minor, and the reversible components of volumetric and shear strains primarily arise from radial contraction and expansion. As the spherical stress increases, the sample volume shrinks (positive volumetric strain), whereas the initial anisotropy leads to negative shear strain, resulting in opposite signs. Finally, a method for predicting irreversible strain under cyclic spherical stress is established based on a memoryless geometric distribution.

Employing soil improvement techniques to mitigate and prevent the detrimental effects of liquefaction on foundations often leads to a significant increase in construction costs in engineering projects. Developing simple, cost-effective, and eco-friendly liquefaction mitigation methods has always been one of the main concerns of geotechnical engineers. Researchers introduced the induced partial saturation (IPS) method to increase the liquefaction resistance of the saturated foundations, which is based on decreasing the saturation degree of the saturated sand. In this study, hollow cylinder torsional shear tests were conducted on loose saturated and desaturated calcareous sand to assess the liquefaction behavior of desaturated sand. Soil compressibility is the primary parameter affecting the liquefaction behavior of desaturated sand. As saturation degree, back pressure, and effective confining pressure significantly influence soil compressibility, their effects on the liquefaction resistance of desaturated sand were investigated. The pore pressure development during cyclic loading reveal that, unlike saturated samples, desaturated samples do not exhibit an excess pore pressure ratio reaching one, even when the double amplitude shear strain surpasses 7.5 %. Finally, the test results demonstrated a notable correlation between liquefaction resistance ratio, maximum volumetric strain, and the maximum generated excess pore pressure ratio, and a pore pressure model was proposed.

This study introduces a novel, interdisciplinary method that merges fundamental geomechanics with computer vision to develop an advanced hybrid feature-aided Digital Volume Correlation (DVC) technique. This technique is specifically engineered to measure and compute the full-field strain distribution in fine-grained soil mixtures. A clay-sand mixture specimen composed of quartz sand particles and kaolinite was created. Its mechanical properties and deformation behaviour were then tested using a mini-triaxial apparatus, combined with micro-focus X-ray Computed Tomography (mu CT). The CT slices underwent image processing for denoising, segmentation of distinct phases, reconstruction of sand particles, and feature extraction within the soil specimen. The proposed approach incorporated a two-step particle tracking method, which initially uses particle volume and surface area features to establish a preliminary matching list for a reference particle and then use the Iterative Closest Point (ICP) method for precise target particle matching. The soil specimen's initial displacement field was then mapped onto the DVC method's grid, and further refined through subvoxel registration via a three-dimensional inverse compositional Gauss-Newton algorithm. The proposed method's effectiveness and efficiency were validated by accurately calculating the displacement and strain fields of the soil mixture sample, and comparing the results with those from a traditional DVC method. Given the soil's compositional and microstructural characteristics, these image-matching techniques can be integrated to create a versatile, efficient, and robust DVC system, suitable for a variety of soil mixture types.

Accurate determination of potassium ion (K+) concentration in fingertip blood, soil pore water, pipette solution, and sweat is crucial for performing biological analysis, evaluating soil nutrients levels, ensuring experimental precision, and monitoring electrolyte balance. However, current electrochemical K+ sensors often require large sample volumes and oversized reference electrodes, which limits their applicability for the aforementioned small-volume samples. In this paper, a K+ sensor integrated with a glass capillary and a spiral reference electrode was proposed for detecting K+ concentrations in small-volume samples. A K+-selective membrane (K+-ISM)/ reduced graphene oxide-coated acupuncture needle (working electrode) was spirally wrapped with a chitosangraphene/AgCl-modified Ag wire (reference electrode). This assembly was then inserted into a glass capillary, forming an anisotropic diffusion region of an annular cylindrical gap with width 410 mu m and height 20 mm. It was found that the capillary action of the glass capillary results in a raised liquid level of the sample inside it compared to that in the container, which promotes efficient contact between the small-volume sample and the K+ sensor. Besides, the formed anisotropic diffusion region limits the K+ diffusion from the bulk solution to the K+ISM, which leads to a larger potentiometric response of the K+-ISM. The glass capillary-assembled K+ sensor displays high performance, including a sensitivity 58.3 mV/dec, a linear range 10_ 5-10_ 1 M, and a detection limit 1.26 x 10_6 M. Moreover, it reliably determines K+ concentrations in artificial sweat of microliter volume. These results facilitate accurate detection of K+ concentration in fingertip blood, soil pore water, and pipette solution.

3D printed concrete has emerged as one of the most hotly researched 3D printing technologies due to its advantages of shaping without molds and intelligent construction. Given its low heat of hydration and low carbon emissions slag-based cement is becoming more widely used for 3D printing concrete. However, in the formwork-free shaping process, freshly printed slag-based concrete is immediately exposed to air and loses moisture much earlier than traditional cast-in-formwork concrete. As a result, there is a greater risk of drying shrinkage and cracking and poor volumetric stability of the printed part. This study investigated applicability of photo-polymerization technology in improving the volumetric stability of 3D printed concrete by using UV-curable polyurethane-acrylate (PUA) resin as in-situ sprayed coating on the surface of freshly printed slag-based cement samples. The results show that, in comparison with the uncoated 3D printed cement samples, the volumetric shrinkage of the coated 3D printed cement samples significantly reduced by 44 % after 28 days of environmental curing. For samples of the same age, the compressive strength of the coated test block was increased by 27 % from 20.03 MPa to 25.49 MPa, and the interlayer bond strength was increased by 41 % from 1.46 MPa to 2.06 MPa. The sprayed UV-curable polyurethane-acrylate resin can cure rapidly on the specimen surface within seconds under the irradiation of UV light to form an in-situ protective coating, which is tightly bonded to the surface of the cement, effectively reducing water dissipation and promoting hydration, allowing more even and condense microstructures to form during hydration from the outer surface to the inner part of the printed sample, resulted in a higher strength.