受青藏高原暖湿化的影响，多年冻土呈现快速退化状态，并由此诱发大量的冻土滑坡灾害。为深入探讨多年冻土区滑坡失稳机制，本研究基于多年冻土滑坡区活动层（融土）粉土、黏土及相应土-冰界面直剪试验结果，通过离散元分析软件MatDEM对应修正了直剪试验模型，并将数值模拟结果与直剪试验结果进行对比分析。结果表明：修正后的直剪模型可有效地对粉土和黏土进行数值模拟计算；模拟与试验结果的剪切特性曲线及抗剪强度拟合曲线变化趋势基本保持一致，且黏土抗剪强度明显低于粉土，表明土体抗剪强度随土颗粒粒度的减小而降低；在土-冰界面处，黏土-冰的抗剪强度最低，土体稳定性最弱。模拟结果中位移场图、单元连接状态图均表明在剪切过程中形成了明显的剪切带，且融土界面处及非界面处颗粒的平均配位数变化规律显示剪切带内的颗粒在试样变形中起到主要作用。此外，热量变化曲线表明，剪切过程中的热量主要来源于剪切带中上下剪切盒产生的摩擦热。本研究可为高原冻土滑坡区土体抗剪强度数值模拟研究提供有效参考模型。
受青藏高原暖湿化的影响，多年冻土呈现快速退化状态，并由此诱发大量的冻土滑坡灾害。为深入探讨多年冻土区滑坡失稳机制，本研究基于多年冻土滑坡区活动层（融土）粉土、黏土及相应土-冰界面直剪试验结果，通过离散元分析软件MatDEM对应修正了直剪试验模型，并将数值模拟结果与直剪试验结果进行对比分析。结果表明：修正后的直剪模型可有效地对粉土和黏土进行数值模拟计算；模拟与试验结果的剪切特性曲线及抗剪强度拟合曲线变化趋势基本保持一致，且黏土抗剪强度明显低于粉土，表明土体抗剪强度随土颗粒粒度的减小而降低；在土-冰界面处，黏土-冰的抗剪强度最低，土体稳定性最弱。模拟结果中位移场图、单元连接状态图均表明在剪切过程中形成了明显的剪切带，且融土界面处及非界面处颗粒的平均配位数变化规律显示剪切带内的颗粒在试样变形中起到主要作用。此外，热量变化曲线表明，剪切过程中的热量主要来源于剪切带中上下剪切盒产生的摩擦热。本研究可为高原冻土滑坡区土体抗剪强度数值模拟研究提供有效参考模型。
Ground reinforced embankment (GRE) is a common and efficient rockfall mitigation measure. However, due to the diversity of geometric dimensions and composite components of the embankments worldwide, the design methods have not yet been unified. This article proposes a DEM-based framework for modeling the GREs impacted by rockfalls, and to optimize the structural design by comparing the block-intercepting performance. The numerical model based on MatDEM is validated by restoring the Peila's field tests, and the simulated materials are calibrated by comparing the laboratory test results. The design elements can be determined through simulated impact tests, with the site topography and rockfall trajectory as prerequisite information. The simulation test results show that the structural positions and cross-sectional shapes alter the interaction between rockfalls and embankments, thereby affecting the block-intercepting capacity. Under the impact of high-energy blocks, the characteristic of structural failure is that the extrusion of the downhill face is greater than the displacement of the uphill face, which can be used as a criteria to determine the reasonable design elements. The proposed framework can be applied to an actual site and maximize the cost-benefit performance of design depending on the site space and budget conditions.
The soils in the eastern region of Qinghai, China, are characterized by typical unsaturated loess with poor engineering properties, rendering them susceptible to geological disasters such as landslides. To investigate the mechanical properties of these soils, triaxial and direct shear tests were conducted, followed by simulations of deformation and stability under freeze-thaw cycles using the discrete element software MatDEM, based on the experimental data. The findings indicate that (1) the stress-strain curves from both tests typically exhibit weak strain-softening behavior, with increased matric suction enhancing shear strength; (2) in the direct shear test, both cohesion (c) and the angle of internal friction (phi) rise with matric suction, whereas in the triaxial test, cohesion increases while phi decreases; and (3) an increase in freeze-thaw cycles results in a gradual decline in slope safety factor, though the rate of decline diminishes over time. Additionally, initial water content and slope gradient changes significantly affect slope stability. These insights are essential for geohazard risk assessment and the formulation of prevention and control strategies in Qinghai and similar alpine regions.
隧道长期运营情况下，由于自身地质条件及日常养护不足等经常导致出现多种病害问题。国家高速公路网荣成至乌海高速公路抢风岭隧道ZK77+265—ZK77+313至K77+213—K77+357段，其地基层以泥岩为主，由于泥岩具有较强的亲水性，隧道在部分仰拱区域产生冻胀、融沉和吸水膨胀3方面病害。基于离散元软件MatDEM对其进行建模，并模拟隧道冻胀融沉和吸水变形的过程。根据试验所得的体变率-吸水率关系，以颗粒粒径增大/缩小的方式来改变颗粒体积，进而完成吸水膨胀、岩体冻胀和融沉过程的模拟。结果表明当地下水位处于4 m以上位置时都能促使隧道破坏，而只有地下水位低于4 m时，对隧道结构的影响较小。
隧道长期运营情况下，由于自身地质条件及日常养护不足等经常导致出现多种病害问题。国家高速公路网荣成至乌海高速公路抢风岭隧道ZK77+265—ZK77+313至K77+213—K77+357段，其地基层以泥岩为主，由于泥岩具有较强的亲水性，隧道在部分仰拱区域产生冻胀、融沉和吸水膨胀3方面病害。基于离散元软件MatDEM对其进行建模，并模拟隧道冻胀融沉和吸水变形的过程。根据试验所得的体变率-吸水率关系，以颗粒粒径增大/缩小的方式来改变颗粒体积，进而完成吸水膨胀、岩体冻胀和融沉过程的模拟。结果表明当地下水位处于4 m以上位置时都能促使隧道破坏，而只有地下水位低于4 m时，对隧道结构的影响较小。
隧道长期运营情况下，由于自身地质条件及日常养护不足等经常导致出现多种病害问题。国家高速公路网荣成至乌海高速公路抢风岭隧道ZK77+265—ZK77+313至K77+213—K77+357段，其地基层以泥岩为主，由于泥岩具有较强的亲水性，隧道在部分仰拱区域产生冻胀、融沉和吸水膨胀3方面病害。基于离散元软件MatDEM对其进行建模，并模拟隧道冻胀融沉和吸水变形的过程。根据试验所得的体变率-吸水率关系，以颗粒粒径增大/缩小的方式来改变颗粒体积，进而完成吸水膨胀、岩体冻胀和融沉过程的模拟。结果表明当地下水位处于4 m以上位置时都能促使隧道破坏，而只有地下水位低于4 m时，对隧道结构的影响较小。
Ground reinforced embankment (GRE) is an economical and efficient protection measure against rockfalls. In various design guidelines of ground reinforced embankments, the impact force of the rockfall is the principal factor, which is significantly affected by rockfall shape. This article conducts real scale tests and numerical tests to observe the external deformation behavior and the internal dynamic response of GREs subjected to lateral impact. Five shapes of the rockfalls corresponding to three contact types are set up in the tests. The experimental results show that the impact surface shapes of the rockfalls govern the penetration deformation patterns of the embankments, and the deformation extent of the disturbed soils. For different contact types between rockfalls and construction materials, the failure mode of the geosynthetics and the displacement distribution of the disturbed soils are distinguishing. The disturbed soils can be divided into two parts, the part surrounds the rockfall mainly expands laterally, and the rest is extruded and slips backward. Basically, the sharpness of the rockfall results in the deeper penetration and the smaller impact force. The influence of the rockfall shape needs to be carefully considered in the design of ground reinforced embankments.
Anthropogenic climate change threatens water storage and supply in the periglacial critical zone. Rock glaciers are widely distributed alpine aquifers with slower response to temperature increases, that provide the summer water flow of many alpine streams. Knowing the extent and makeup of rock glaciers is necessary to evaluate their potential for water supply. We used non-invasive methods, integrating geological, geomorphological, meteoro-logical, and geophysical information to characterize the internal structure and hydrology of the Upper Camp Bird rock glacier (UCBRG) located on level 3 of Camp Bird Mine in Ouray, Colorado, and assessed the applicability of two electromagnetic induction systems in this highly heterogeneous landform with a history of anthropogenic activity. The time-domain (G-TEMTM) system achieved deep subsurface penetration (similar to 100 m) and realistic modeling of the internal structure of the UCBRG: a shell of volcanic rock fragments (< 3 m thick; 1-100 Ohm-m), a meltwater component (10(2)-10(3) Ohm-m), located between 50 and 100 m near the toe (subpermafrost flow), and 1-30 m in the soundings farthest from the toe (suprapermafrost flow within the active layer), and a frozen component (permafrost 50-80 m thick; 10(3)-10(6) Ohm-m). The frequency-domain system, however, was highly susceptible to local environmental conditions, including anthropogenic objects (i.e., mine carts, lamp posts, tunnel tracks, etc.) and was unable to resolve UCBRG's internal makeup. The non-invasive methodology and general conceptual framework presented here can be used to characterize other alpine aquifers, contributing to the quantification of global water resources, and highlighting the importance of preserving rock glaciers as storage for critical water supply in the future.