利用1990—2024年间的Landsat遥感影像与气象数据，文章通过多时相影像计算归一化水体指数NDWI，结合K-means聚类方法计算羊卓雍措面积，并用一元线性拟合分析其变化趋势。羊湖在1996—2004年间显著扩张，受降水和融水补给增加，输入量超过输出量；2004—2014年间则经历了明显的缩减，归因于气温升高加剧蒸发，且融水和降水输入未显著变化，导致输入量小于输出量。利用傅里叶变换分析湖泊面积时序特征，发现其变化具有低频特性。在不同时间尺度上，羊湖面积的变化受降水、气温和积雪影响的具体过程各不相同。在超过15年周期（0.03 Hz,0.06 Hz）的低频变化中，羊湖面积与降水呈弱相关性，主要受到气温升高和积雪融化的影响，涉及蒸发量的增减以及积雪融化的促进或抑制。在10～15年周期（0.09 Hz,0.12 Hz）范围内，湖泊面积变化由降水和气温共同调控，影响湖泊水量的收支平衡。气候变暖是驱动羊湖面积年代尺度上变化的主要因素。

With transportation's rapid growth, ship-bridge collisions occur frequently, causing substantial losses. Ship-bridge anticollision facilities should not only protect the structural integrity of bridges but also minimise ship damage. This paper designs a novel ship-bridge anti-collision device based on a trapezoidal foam-filled composite sandwich structure. Using the finite element software LS-DYNA, a ship-anti-collision device-bridge collision model was established, taking into account pile-water-soil coupling. The study investigates the selection of box materials, filling materials and wall thickness for the novel anti-collision device. By analysing the damage characteristics of the ship, anti-collision device and pier under typical collision loads, the optimal material properties were determined. The impact resistance of the optimised device was evaluated under different ship speeds and collision angles, demonstrating that the novel anti-collision device exhibits excellent buffering and energy absorption, effectively reducing the peak collision force, extending the collision duration and reducing damage to the ship's bow structure.

热融湖塘是多年冻土退化所引起的热融灾害之一，其中准确地监测热融湖塘的分布和变化是评估这一灾害的前提。根据以往对热融湖塘的研究发现，小型热融湖塘较多，但由于热融湖塘分布在湿地、草地等不同区域，部分热融湖塘在影像上与周边环境出现同谱异物的现象，导致无法对小型热融湖塘进行准确统计。本文选取高分六号影像作为数据源，分别采用归一化差异水体指数（NDWI）阈值法、面向对象提取法、LBV变换法对研究区内热融湖塘进行提取。通过解译结果分析，LBV变换法提取精度最高；GF-6影像经过LBV变换之后，水体与其他地物之间的差异更加突出，对小型热融湖塘的提取有较好的适用性。

This paper aims to systematically describe the mesostructural and mechanical changes in the surrounding soil of glass fiber-reinforced polymer-trapezoidal core sandwich piles (GFRP-TCSPs) under lateral loads. A lateral loading device for hydraulic gradient testing is introduced, and a corresponding numerical model is established using a continuum-discrete coupling method. The dynamic interaction between the GFRP-TCSP and the soil during incremental loading is analyzed, including the effect of the soil particle contact parameters on the pile-soil interaction (PSI), changes in the pile bending moment, and the displacement field of the surrounding soil. The development of soil force chains and changes in porosity and coordination number in different zones of the soil around the pile are investigated. The results indicate that the attraction and friction between particles are crucial for the PSI behavior of the soil. In addition, the bending moment of the pile increases with increasing lateral load but decreases when the pile inclination angle diverges significantly. Different regions of the soil around the pile exhibit different variations in average contact force, porosity, and coordination number as the GFRP-TCSP overturns. These variations provide a theoretical basis for detecting pile instability.

Composite construction materials are widely utilized and have demonstrated superior efficiency compared to their constituent materials, such as steel and concrete. Despite their structural integrity and energy efficiency, reinforced concrete sandwich panels face limited adoption in numerous rural areas of developing countries like Pakistan, primarily due to the financial constraints of the population. Hence, this study proposes economical reinforced mud sandwich panels (RMSPs) incorporating mud wythes and investigates their flexure behavior. Mud being the commonly used construction material in rural areas, is readily available, making reinforced mud sandwich panels a potential viable alternative to conventional concrete sandwich panels. Three full-scale models of RMSPs were fabricated. The panels consist of an expanded polystyrene (EPS) layer reinforced with welded galvanized steel wires forming a mesh structure and shear connectors. In addition, both sides of the EPS were plastered with a layer of stabilized mud to create wythes of RMSPs. A stabilized mud mixture was prepared by combining constituents in the following proportions by weight: 67% soil, 10% cement, 1% wheat straw, and 22% water. All three RMSPs were tested under four-point loading. Two RMSP panels (RMSP-1 and RMSP-2) were tested by increasing the load gradually until failure. While the third panel (RMSP-3) was subjected to cyclic loading up to 7 kN, the load was then progressively increased till failure. According to the results obtained, the failure of the RMSPs occurred due to the EPS (core) fracture and crack propagation in the lower wythe under flexural stresses. Nonetheless, the panel resisted structural collapse despite experiencing significant midspan deformation. Numerical analysis of RMSP was also performed using finite element software (ABAQUS). The results demonstrated a strong correlation between numerical simulation and experimental results. RMSP exhibits promise as a potential alternative in sustainable construction technology, offering sufficient load-bearing capability and favorable structural properties such as ductility.

Liquefaction poses a potential threat to the safety, serviceability and stability of shield tunnels during seismic events. This study investigates the seismic response of shield tunnels in liquefiable soils employing a fully coupled dynamic effective stress analysis model. The model accounts for the nonlinear mechanical behavior of the shield tunnel structure and incorporates the advanced bounding surface elastoplastic PM4Sand and PM4Silt models integrated with Biot u - p formulation to simulate the constitutive behavior of liquefiable and nonliquefiable soil layers. The seismic performance of shield tunnel -liquefiable soil system is evaluated considering ground motions with different characteristics in the transverse direction. The numerical results reveal the significant effects of ground motion frequency content and seismic intensity on the liquefaction triggering, the tunnel deformation and the internal forces of segmental joints. The soil -structure dynamic interaction and the soil shear dilatancy characteristics greatly influence the generation of the earthquake -induced excess pore water pressure and post -liquefaction shear strains. It is observed that the soil contact pressures on the left and right springlines of the tunnel experience larger increase compared to the contact pressure on the tunnel crown and invert. This observation suggests that the soil could cause racking deformation on both sides of the tunnel structure towards the center. Besides, the deformations and mechanical behaviors of the segmental joints around the tunnel left and right feet and the right springline are notably higher than at other joints in the saturated deposits. Furthermore, it is found that ground motion characterized by low -frequency contents, amplifies the seismic response of the soil and the tunnel when compared to the ground motions with high or moderatefrequency contents.

Sandwich pipe (SP) is regarded as an ideal deep water oil and gas transportation solution and has attached more and more attention attributed to its good structural resistance and thermal insulation performance. The local dent damage of SP induced by the falling objects impact might result in the leakage of oil and gas resources. This work investigates the dent behavior of sandwich pipes subjected to falling object impact through finite element (FE) numerical simulation by considering the effect of seabed flexibility. A three-dimensional FE model was established and validated to accurately capture the structural behavior of SP lying on the seabed. The sensitive parameters studies were performed to assess the influence of falling object mass, kinetic energy and buried depth on the dent characteristics. The results show that the flexible seabed foundation can effectively reduce the local dent damage degree of sandwich pipes and most of the kinetic energy is dissipated by the annular layer so as to provide protect for the steel pipes. Besides, the outer pipe, annular layer and inner pipe show different dent depth and strain levels as the kinetic energy of falling objects changes. The degree to which the speed and mass of falling objects affect the characteristics of depressions depends on the magnitude of the kinetic energy of the falling object. Based on the parameters analyses, a group of empirical formulas are established to provide prediction of dent depth and dent strain for sandwich pipes.

The China-Pakistan Economic Corridor (CPEC), a key hub for trade, is susceptible to glacial lake outburst floods. The distributions and types of glacial lakes in the CPEC are not well documented. In this study, cloud-free imagery acquired using the Landsat 8 Operational Land Imager during 2016-2018 was used to delineate the extent of glacial lakes in the mountainous terrain of the CPEC. In the study domain, 1341 glacial lakes (size >= 0.01 km(2)) with a total area of 109.76 +/- 9.82 km(2) were delineated through the normalized difference water index threshold method, slope analysis, and a manual rectification process. On the basis of the formation mechanisms and characteristics of glacial lakes, four major classes and eight subclasses of lakes were identified. In all, 492 blocked lakes (162 end moraine-dammed lakes, 17 lateral moraine-dammed lakes, 312 other moraine-dammed lakes, and 1 ice-blocked lake), 723 erosion lakes (123 cirque lakes and 600 other erosion lakes), 86 supraglacial lakes, and 40 other glacial lakes were identified. All lakes were distributed between 2220 and 5119 m a.s.l. At higher latitudes, the predominate lake type changed from moraine-related to erosion. From among the Gez, Taxkorgan, Hunza, Gilgit, and Indus basins, most glacial lakes were located in the Indus Basin. The number and area of glacial lakes were larger on the southern slopes of the Karakoram range.