Due to the insufficient burial depth of shallow-buried foundation bridges, foundation voiding easily occurs during floods or rapid water flows. When heavy vehicles pass over these partially voided bridges, the stress state of the foundation deteriorates instantaneously, causing critical components to exceed their load-bearing capacity in a short period, leading to a chain reaction that results in the rapid collapse and overall failure of the bridge structure. Previous numerical simulations of bridge water damage often neglected the strong coupling between water flow, soil, and structure during the scouring process. This paper applies a fluid-solid coupling simulation modeling method for bridge damage behavior under scouring action to study the structural damage behavior of shallow-buried foundation bridges under the combined effects of flood scouring and heavy vehicle load. This method employs point cloud reverse engineering technology to solve the difficult problem of converting the complex scour morphology around the foundation under flood scouring into a structural model, and investigates the multi-hazard damage behavior of shallow-buried foundations by coupling extreme hydraulic effects on the pier surface and placing the most unfavorable heavy vehicle loads on the bridge deck.

Cavities behind the concrete lining of a shield tunnel may result in apparent damage or even collapse of the tunnel during its operation. It is necessary to predict the damage modes of a shield tunnel with cavities, and accordingly reinforce vulnerable areas of the tunnel. This paper investigates the damage modes of shield-tunnel models with cavities at different locations and sizes behind the concrete lining. The tunnel models used in the test are created using a 3D printing technique, with an aim of simulating the joints between segments. To consider the stratum-structure interaction, the tunnel models are created with grout-layers prefabricated between lining and soil. The 3D point cloud technique is then applied to observe the damage modes of the tunnel linings. The safety status of the shield tunnel is evaluated during the loading process, and categorized into safe, dangerous, and failure stages. Experimental results show that the damage modes of the shield tunnel with cavities contain concrete crack, concrete spalling, segment misalignment, and lining crush. Cavities at the tunnel crown and shoulder impose a substantial impact on the lining structure. Cracks propagating across three or more segments result in mutual compression between segments, forming a crack mesh, and consequently leading to concrete spalling. The tunnel lining undergoes a failure mode of segment misalignment when the cavity angle (size) is greater than 45 degrees. As the volume of the cavity increases, the tunnel lining transitions to a failure mode of lining crush. The results in this study will facilitate the proactive reinforcement of the tunnel by predicting damage modes induced by cavities, ensuring its safe operation to a certain extent.

Port pavements often experience damage, such as differential settlements and cracks, owing to soft ground and heavy equipment operations. This study focuses on developing and applying port blocks in two configurations within a port to assess its applicability based on deflection and settlement characteristics. Falling weight deflectometer (FWD) tests were carried out on both asphalt and block pavements to measure deflection and bearing capacity. Results indicate that the block pavement with a cement-treated base exhibited improved bearing capacity and settlement performance during port operations compared to asphalt pavement. This improvement was evident in the relative deflection and relative bearing ratios, where the cement-treated base demonstrated enhanced bearing capacity over asphalt. Light detection and ranging (LiDAR) measurements revealed several settlements in the crushed-stone base due to surface loads post- construction. While both relative deflection and relative bearing ratios indicated settlement tendencies, the latter proved more consistent with the settlements. The settlements were generally less than 5 cm with the superior bearing capacity block pavement presents itself as a viable pavement for various port settings.

Soil surface roughness (SSR) is an important indicator that characterizes the microtopography feature of farmland after tillage. It has a high practical value for sowing and seedling raising, farmland management, and drainage irrigation in agricultural production. The traditional method often is prone to damage the surface microstructure and results in low efficiency and accuracy. In this study, a new method was proposed to address the limitations of traditional measurement methods of SSR. The proposed measurement and evaluation method of farmland microtopography feature information based on 3D lidar and inertial measurement unit (IMU) could be used to quickly obtain the global point cloud map containing the height data of the test field. Taking three different tillage methods of farmland as the research object, the surface root mean square height (RMSH), correlation length (CL), and their ratio were selected as roughness parameters to explore the anisotropy of microtopography features in different directions. The measurement method was then used to study the effects of sampling processing methods (number, interval, and length) on the measurement accuracy in both OX and OY directions. The results indicate that under the same accuracy requirements, for the 2 x 2 m area, the farmland with different microtopography features needs to be processed with different sample numbers, sample intervals, and sample lengths. The optimal combination of sample parameters for Test field I is sample number of 50, sample interval of 120 mm, and sample interval of 1600 mm, and that in Test field II is sample number of 50, sample interval of 160 mm, and sample interval of 1800 mm. For Test field III, the optimal combination is sample number of 100, sample interval of 40 mm, and sample length of 1200 mm. The experimental results compared with the traditional method illustrate the high accuracy and good feasibility of the proposed method for measuring and evaluating the microtopography feature information of the farmland. The results of the study help to understand the microtopography features and its parameterization of the farmland after tillage, which could further reveal the role and significance of SSR parameters in objectively evaluating farmland tillage quality and optimizing farmland management.

Fragmented surfaces and harsh environments have always been the main obstacles hindering observation works of glaciers in central Tibetan Plateau (TP). The advent of Terrestrial Laser Scanner (TLS) technology offers a potential revolution in this context. While TLS has been effectively applied to smaller glaciers in the Alps and Tianshan, this study extends its use to the large and topographically complex Ganglongjiama (GLJM) glacier in the Tanggula Mountains. Over a 5-year period, TLS, with a precision of up to 0.012 m, has documented an accelerated melting trend, with the terminus retreating by 13.305 m and a total mass loss of 2.580 m water equivalent. The research also underscores the role of supraglacial channels and lakes in intensifying surface melting and glacier front instability. Despite challenges in data acquisition due to occlusions and logistical constraints at high altitudes, this first TLS survey of a TP glacier provides invaluable insights into glacier dynamics. Future research could integrate TLS with Unmanned Aerial Vehicle-Structure-from-Motion (UAV-SfM) data fusion to achieve more comprehensive coverage and improve the temporal resolution of observations for a detailed analysis of glacier features.