Buried pipes are subjected to static and dynamic loads depending on their areas of use. To mitigate the risk of damage caused by these effects, various materials and reinforcement methods are utilized. In this study, five buried uPVC pipes designed in accordance with ASTM D2321 standards were reinforced with three different ground improvement materials: Geocell, Geonet, and Geocomposite, and experimentally subjected to dynamic impact loading. Acceleration, velocity, and displacement values were obtained from the experiments. Subsequently, finite element analysis (FEA) was performed using the ABAQUS software to determine stress values and volumetric displacements in the pipes, and the model was validated with a 5-7% error margin. In the final stage of the study, a parametric analysis was conducted by modifying the soil cover height above the pipe and the Geocell thickness in the validated finite element model. The parametric study revealed that the displacement value in the pipe decreased by 78% with an increase in soil cover height, while a 16% reduction was observed with an increase in Geocell thickness. The results demonstrate that the soil improvement techniques examined in this study provide an effective solution for enhancing the impact resistance of buried pipeline systems.

The study examines the toxicity of cadmium (Cd), microplastics (MPs) and their combined pollution on wheat plants, focusing on Cd accumulation and alterations to soil physical and chemical properties. To provide guidance for understanding the physiological and ecological responses of wheat to Cd and MPs contamination. Using a soil pot experiment, the individual and combined impacts of Cd (0 mg kg(-)(1) and 5 mg kg(-)(1)) and polyvinyl chloride microplastics (PVC-MPs) (0%, 0.5%, 1.0%, and 5.0%) on various aspects of wheat growth were assessed. Partial least square (PLS) model was employed to analyze the quantitative relationship between wheat growth indicators and various physicochemical parameters. Results revealed that the PVC-MPs significantly suppressed wheat growth parameters, photosynthetic efficiency, and chlorophyll content. As the level of contamination increased, the damage to wheat chloroplasts became more severe, leaf thickness reduced, and canopy temperatures rose. Conversely, root morphology parameters and Cd accumulation in wheat plants exhibited a declining trend. Moreover, soil fertility indicators and the activities of soil urease, acid phosphatase and dehydrogenase increased in correlation with higher concentrations of PVC-MPs. The PLS model identified stomatal conductance as the critical controlling factor influencing wheat growth under the combined stress of PVC-MPs and Cd. Overall, co-occurring Cd and PVC-MPs can change wheat plant performance and soil traits. These findings provide crucial insights into the physiological and ecological impacts of Cd and microplastic co-pollution in wheat-soil systems.

Vessel collisions on bridge piers have become a potential threat to the safety of bridges crossing navigation waterways. Such collision will cause inevitable damage on bridge piers and hence reduce the performance of the whole structure. It is therefore critical to identify the condition of abridge pier after a vessel collision event to judge whether it can still be used or certain rehabilitation is required to recover its normal operation. This paper develops an intelligent approach based on machine learning algorithms to identify the evolution process of damage on abridge pier during collision using sensor-measured acceleration time-history data considering the effects of multi-hazards. A barge vessel is employed and atypical reinforced concrete (RC) bridge pier is considered in this study. A coupled vessel-pier collision model (CVCM) considering soil-pile interactions and material non-linearity of RC components is developed and employed to generate pseudo-experimental data to assess the accuracy of the proposed damage identification strategy. The results demonstrate the potential of the proposed strategy for intelligent damage identification of waterway-crossing bridge piers after vessel collision.

In this investigation, the electromagnetic effects of lightning on uncoated and PVC-coated high-steel metal buried pipes are numerically modelled and analyzed at varying earth surface depths of 1-2 m and varying PVC coating material thicknesses of 0.001-0.002 m. A typical lightning-injected current waveform was taken into consideration, and the corresponding return stroke current along the channel at different heights was thoroughly studied initially when it struck the earth's surface to validate the model. The study found that the density of induced current and field strength below the earth's surface is significantly impacted by the depth, with shallower depths having greater influence. The field strength and density of the induced current decrease with increasing depth. As seen, the insulation of PVC-coated metal buried pipe facilitates a higher density of induced current on the upper surface of the PVC coating, particularly for the finite earth surface conductivity (0.01 Sm-1). For finite earth surface conductivity (0.01 Sm-1) and a PVC-coated thickness of 0.0015 m at a fixed 0.105 m PVC coating diameter, the density of induced current at the mid- of the PVC top surface reaches about 6696.37 Am-2. Additionally, the density of induced current at the mid- of the pipe top surface was found to be about 14 Am-2, significantly lower than 5047.09 Am-2 for the uncoated metal buried pipe at the same depth. PVC-coated metal buried pipe has significantly lower induced currents than uncoated metal buried pipe at shallower depths. The proposed structure and reported analysis of PVC coating thickness may be beneficial in developing the mechanism of failure and designing a prevention plan for high-steel metal buried pipes from burns or physical damage.

The vegetation in Huayuan County was seriously damaged during the mining process. Using remote sensing data, the vegetation coverage in the Huayuan County lead-zinc mining area was analysed to explore the temporal trends and driving factors of the FVC. As calculated from remote sensing data, the average FVC decreased rapidly from 0.74 to 0.36 from 2000-2008, with no significant change from 2009 to -2018, and gradually recovered from 0.36 to 0.5 from 2019-2024. Two typical mining areas were selected for research. After artificial reclamation, the damaged vegetation can be restored, whereas the vegetation in the naturally restored mining area is difficult to restore. The cluster map of the mining area is obtained via the Moran index, which reveals that artificial reclamation has an obvious effect on vegetation restoration. The destruction of vegetation in mining areas is affected primarily by human activities, while human activities are affected primarily by changes in policy; thus, policy factors are the main factors driving changes in vegetation in mining areas, whereas natural factors have a small influence on changes in the FVC in mining areas. This study provides a theoretical basis for vegetation restoration in other mining areas and promotes sustainable development.

Coral soil in large quantities of islands has been used for the construction of islands with the development of global marine construction projects. At present, the research on the macro and micromechanical behavior of coral soil during loading is insufficient, which is related to the development of marine engineering. Using the self-developed high-pressure geotechnical CT-triaxial apparatus, the consolidated drained triaxial tests were conducted on coral gravel under confining pressures ranging from 200 to 800 kPa, all the while employing realtime CT scanning to monitor the sample's deformation. The deformation, particle breakage, and porosity of coral gravel could be directly observed by CT images and its post-processing. The results show that the stress-strain relationship of the samples is strain hardening. Notably, particle breakage during consolidation predominantly manifests as corner breakoff, whereas shearing processes primarily induce splitting. The relative breakage Br is not only approximately linear with the average coordination number C-N of particles, but also with the logarithm of average particle size d, porosity n, and local strain s. Observing the evolution of the sample during loading, the increase of confining pressures leads to the decrease of the sample porosity, resulting in a diminishment in pore dimensions, a densification of particle packing, and the increase of contacts between particles. Consequently, this induces particle breakage and continuous volumetric contraction, thus the stress-strain relationship is hardening. The reciprocal influence between macroscopic and microscopic mechanics manifests in coral gravel. The experimental findings could provide valuable insights for marine engineering construction.

Open-pit coal mining inevitably damages the soil and vegetation in mining areas. Currently, the restoration of cold and arid open-pit mines in Xinjiang, China, is still in the initial exploratory stage, especially the changes in soil nutrients in spoil dumps over time. Dynamic remote sensing monitoring of vegetation in mining areas and their correlation are relatively rare. Using the Heishan Open Pit in Xinjiang, China, as a case, soil samples were collected during different discharge periods to analyze the changes in soil nutrients and uncover the restoration mechanisms. Based on four Landsat images from 2018 to 2023, the remote sensing ecological index (RSEI) and fractional vegetation cover (FVC) were obtained to evaluate the effect of mine restoration. Additionally, the correlation between vegetation changes and soil nutrients was analyzed. The results indicated that (i) the contents of nitrogen (N), phosphorus (P), potassium (K), and organic matter (OM) in the soil increased with the duration of the restoration period. (ii) When the restoration time of the dump exceeds 5 years, N, P, K, and OM content is higher than that of the original surface-covered vegetation area. (iii) Notably, under the same restoration aging, the soil in the artificial mine restoration demonstration base had significantly higher contents of these nutrients compared to the soil naturally restored in the dump. (iv) Over the past five years, the RSEI and FVC in the Heishan Open Pit showed an overall upward trend. The slope remediation and mine restoration project significantly increased the RSEI and FVC values in the mining area. (v) Air humidity and surface temperature were identified as key natural factors affecting the RSEI and FVC in cold and arid open pit. The correlation coefficients between soil nutrient content and vegetation coverage were higher than 0.78, indicating a close and complementary relationship between the two. The above results can clarify the time-effect relationship between natural recovery and artificial restoration of spoil dumps in cold and arid mining areas in Xinjiang, further promoting the research and practice of mine restoration technology in cold and arid open pits.

Vessel collisions pose significant threats on the safety of cross-channel bridges. Previous studies have paid little attention on the impact performance of common arch bridges with gravity foundations in inland waterways. This study aims to comprehensively investigate the anti-impact resistance and analyze the damage and failure mechanisms of arch bridges under vessel collisions. The entire process of vessel-bridge collision is simulated using three-dimensional explicit finite element technique. The damage characteristics, as well as the progressive collapse process of arch bridge are investigated thoroughly. Moreover, the rational calculation method for bridge lateral resistance against vessel collisions (BRaVC) is discussed. The results show that the gravity foundation bottom of arch bridge can be fixed in vessel-bridge collision numerical analysis due to insignificant foundation-soil interaction. The head-on barge collision on the bridge pier leads to indistinctive lateral displacement, while obvious local damage can be observed. The impact displacement of the bridge pier is not positively correlated with the impact energy according to the impact load spectra analysis. Barge collision on the main arch results in the progressive collapse of the bridge due to unbalanced horizontal thrust from the arch on the other side. The rational BRaVC can be calculated by using sectional strength based on elastoplastic analysis.

介绍了基于VC++的月球车的数据采集处理系统。利用数字罗盘对月球车机器人的俯仰角、航向角和横滚角进行数据采集,并通过对话框实时得到检测数据。采用模糊控制的研究策略,运用MFC对采集的数据进行处理,使机器人的姿态测量精度稳定在±5°左右,有效地保持了机器人在运行中的水平状态,验证了该数据采集处理系统在保持机器人水平运行中的可行性。