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The use of a micropile group is an effective method for small and medium-sized slope management. However, there is limited research on the pile–soil interaction mechanism of micropile groups. Based on transparent soil and PIV technology, a test platform for the lateral load testing of slopes was constructed, and eight groups of transparent soil slope model experiments were performed. The changes in soil pressure and pile top displacement at the top of the piles during lateral loading were obtained. We scanned and photographed the slope, and obtained the deformation characteristics of the soil interior based on particle image velocimetry. A three-dimensional reconstruction program was developed to generate the displacement isosurface behind the pile. The impacts of various arrangement patterns and connecting beams on the deformation attributes and pile–soil interaction mechanism were explored, and the pile–soil interaction model of group piles was summarized. The results show that the front piles in a staggered arrangement bore more lateral thrust, and the distribution of soil pressure on each row of piles was more uniform. The connecting beams enhanced the overall stiffness of the pile group, reduced pile displacement, facilitated coordinated deformation of the pile group, and enhanced the anti-sliding effect of the pile–soil composite structure.

With the advancement of engineering techniques, underground shield tunneling projects have also started incorporating emerging technologies to monitor the forces and displacements during the construction and operation phases of shield tunnels. Monitoring devices installed on the tunnel segment components generate a large amount of data. However, due to various factors, data may be missing. Hence, the completion of the incomplete data is imperative to ensure the utmost safety of the engineering project. In this research, a missing data imputation technique utilizing Random Forest (RF) is introduced. The optimal combination of the number of decision trees, maximum depth, and number of features in the RF is determined by minimizing the Mean Squared Error (MSE). Subsequently, complete soil pressure data are artificially manipulated to create incomplete datasets with missing rates of 20%, 40%, and 60%. A comparative analysis of the imputation results using three methods—median, mean, and RF—reveals that this proposed method has the smallest imputation error. As the missing rate increases, the mean squared error of the Random Forest method and the other two methods also increases, with a maximum difference of about 70%. This indicates that the random forest method is suitable for imputing monitoring data.

The buoyancy of underwater can cause the underground granary to overall float, or even overturn, and the interaction between the soil and underground granary is the key to its stability. This paper introduces a non-contact experiment system utilizing the digital image correlation (DIC) technology and particle image velocity (PIV) technology, and its measurement accuracy is analyzed. Then, this system is employed to study the granary displacement and the soil deformation around the granary subjected to the buoyancy of water. Results show that with the increase of the degree of compaction of the soil around the granary, the floating water level increases by 10.77% and the vertical displacement decreases by 17%. When the soils around the granary are loose sands, the soil deformation range shows an obvious inverted triangle. When the soils are medium dense sands, the soil deformation zone concentrates at the junction of the conical granary bottom and granary wall. When the soils are dense sands, the disturbed range of the soil obviously reduces, and the soil deformation concentrates on both sides of the granary wall and is distributed symmetrically. Finally, taking the medium dense sands around the granary as an example, the reasons for the unstable failure of the granary subjected to buoyancy are discussed, assisted by the soil pressure theory of retaining wall. With the granary increasingly inclining, the soil deviating from the inclined direction of the granary loses its support, which drives the soils to reach the active limit state. The soil in the inclined direction of the granary is squeezed, resulting in passive soil pressure on the granary wall. The soil deformation increases continuously to a passive limit equilibrium state, and the soil continuously develops a sliding surface, resulting in the unstable failure of the granary. This research is expected to provide the technical guidance for the design and popularization of underground granaries.

A novel fiber-optic based earth pressure sensor (FPS) with an adjustable measurement range and high sensitivity is developed to measure earth pressures for civil infrastructures. The new FPS combines a cantilever beam with fiber Bragg grating (FBG) sensors and a flexible membrane. Compared with a traditional pressure transducer with a dual diaphragm design, the proposed FPS has a larger measurement range and shows high accuracy. The working principles, parameter design, fabrication methods, and laboratory calibration tests are explained in this paper. A theoretical solution is derived to obtain the relationship between the applied pressure and strain of the FBG sensors. In addition, a finite element model is established to analyze the mechanical behavior of the membrane and the cantilever beam and thereby obtain optimal parameters. The cantilever beam is 40 mm long, 15 mm wide, and 1 mm thick. The whole FPS has a diameter of 100 mm and a thickness of 30 mm. The sensitivity of the FPS is 0.104 kPa/με. In addition, automatic temperature compensation can be achieved. The FPS’s sensitivity, physical properties, and response to applied pressure are extensively examined through modeling and experiments. The results show that the proposed FPS has numerous potential applications in soil pressure measurement.