Jinhui Li

Background: On May 1, 2024, a landslide occurred on the embankment slope of the Meizhou-Dapu (Meida) Expressway in Guangdong Province, China, resulting in the collapse of a section of pavement, 23 vehicle crashes, 48 deaths, and 30 injuries. This study utilized the small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) in conjunction with Sentinel-1 A radar remote sensing images to compile the temporal and spatial distributions of surface displacement of the Meida embankment slope. By integrating satellite remote sensing images, site conditions, rainfall records, and digital elevation model (DEM), the displacement pattern of the embankment slope was analyzed, and the mechanism of the landslide was revealed. Results: The results show that there is an obvious cumulative displacement concentration in the landslide area before the landslide, cumulative displacement progressively increased towards the slope toe, and an obvious separation trend is observed between the slope crest and the slope toe. In addition, the temporal displacement results show the consistent relationship between surface displacement and rainfall. Conclusions: The research results indicate a slowly progressive separation trend between the slope crest and the toe long before the accident, indicating a traction-type landslide mode. The surface displacement is significantly correlated with seasonal rainfall, which validates the conclusion that the abnormally heavy rainfall is the main triggering factor of this landslide. This study demonstrates the effectiveness of integrated remote sensing technologies in monitoring the slowly changing traction landslide, like the Meida landslide, which could be a promising approach for the monitoring and early warning of landslide hazards in the future.

The accuracy of the initial void ratio is vitally important to ensure the exact position of the normal compression line of remolded clay. In this article, a series of standard oedometer tests were performed on four different types of commercial clay in slurry state to analyze the error sources that affect the experimental accuracy of the initial void ratio. For remolded clay, it is found that the extra water at the end of the test has an unfavorable effect on the calculation accuracy. The precautions and steps for ensuring the experimental accuracy of initial void ratio in the oedometer test are detailed. According to the error propagation theory, the error estimation of five methods commonly used in the literature for calculating the initial void ratio is revealed. On this basis, a novel data fusion approach based on Bayesian inference is proposed to determine the initial void ratio of remolded clay, which fully considers the uncertainty of measurement error. The effectiveness of the proposed Bayesian data fusion approach has been validated by the data from mercury intrusion porosity testing, promoting the application of Bayesian theory in soil mechanics.

Identification of slope subsurface strata for natural soil slopes is essential to assess the stability of potential landslides. The highly variable strata in a slope are hard to characterize by traditional boreholes at limited locations. Ground-penetrating radar (GPR) is a non-destructive method that is capable of capturing continuous subsurface information. However, the accuracy of subsurface identification using GPRs is still an open issue. This work systematically investigates the capability of the GPR technique to identify different strata via both laboratory experiments and on-site examination. Six large-scale models were constructed with various stratigraphic interfaces (i.e., sand–rock, clay–rock, clay–sand, interbedded clay, water table, and V–shaped sand–rock). The continuous interfaces of the strata in these models were obtained using a GPR, and the depths at different points of the interfaces were interpreted. The interpreted depths along the interface were compared with the measured values to quantify the interpretation accuracy. Results show that the depths of interfaces should be interpreted with the relative permittivity, back-calculated using on-site borehole information instead of empirical values. The relative errors of the depth of horizontal interfaces of different strata range within ±5%. The relative and absolute errors of the V–shaped sand–rock interface depths are in the ranges of [−9.9%, 10.5%] and [−107, 119] mm, respectively. Finally, the GPR technique was used in the field to identify the strata of a slope from Tanglang Mountain in China. The continuous profile of the subsurface strata was successfully identified with a relative error within ±5%.

Since concrete is cheaper and more resistant to corrosion than steel, the wide-shallow concrete bucket foundation is being used extensively in ocean engineering. By adding the inner bucket and cruciform skirts, both the bearing capacity and rigidity of the wide-shallow concrete bucket foundation increase significantly. When compared to the hollow steel bucket foundation, the inclusion of thicker skirts, as well as the addition of inner bucket and cruciform skirts, would cause changes to the soil flow mechanism, resulting in soil heave within each compartment and changes in soil strength evolution and penetration resistance during installation in clay. In order to study the influence of the addition of the inner bucket and cruciform skirts on the soil heaving inside each compartment, soil softening and penetration resistance, three-dimensional large deformation finite element (LDFE) models for the bucket foundation with and without inner bucket, and cruciform skirts considering soil remolding were established using the Coupled Eulerian–Lagrangian (CEL) approach. It was found that the inner bucket significantly changes the soil flow and softening of the soil during penetration of the bucket foundation. According to the theoretical analysis and numerical results, the diameter of the optimal inner bucket is equal to 5/8 of the outer diameter. The adhesion coefficient observed in this study falls within the range of 0.5 to 0.8, which is higher than the theoretical value of 0.25 that assumes the soil is fully remolded. The reason for this discrepancy is that the soil is only partially remolded during the actual installation of the bucket foundation. The neglect of the softening of the soil or considering the soil as completely softened will result in significant variation in the predicted penetration resistance; hence, partial softening of the soil should be taken into account.