Extensive Cenozoic red-bed mudstone, highly susceptible to slope failure, is distributed across the NE Tibetan Plateau. These rocks undergo progressively deterioration under repeated wet-dry cycling (WDC) driven by intense seasonal rainfall, ultimately forming slip surfaces. However, the multiscale mechanisms governing this deterioration and instability remain poorly understood. To address this, we applied a multiscale investigation integrating field observations, X-ray diffraction (XRD), scanning electron microscopy (SEM), computed tomography (CT), triaxial testing, and numerical modeling. The results reveal the evolution of red-bed mudstone under WDC, from mineral dissolution and pore expansion to fracture interconnection, stress concentration, and mechanical degradation. Key findings include: (1) Differential dissolution of clay minerals (e.g., kaolinite) and feldspar increases the porosity from 1.8 % to 16.3 %, triggering the initial deterioration; (2) WDC further raises the porosity from 9.8 % to 16.9 %, interconnects isolated fractures into a continuous network, and enhances permeability from 10.2 x 10-6 to 561.9 x 10-6 Darcy, accelerating internal structural degradation; (3) This evolving degradation network induces stress concentration, leading to a 84 % reduction in strength (from 8905.68 to 1419.85 kPa) and a 79.5 % reduction in cohesion (from 1931.4 to 395.8 kPa), substantially weakening the slope stability; (4) At the slope scale, an "externally dry, internally wet" structure develops, where the coupled effects of mineral dissolution, pore evolution, permeability enhancement, and strength loss drive a progressive creep failure, characterized by external fracturing and internal softening. Thus, this study establishes a multiscale coupled evolution model and elucidates how WDC induces differential sliding in red-bed slopes, providing a theoretical basis for landslide prediction in such regions.

山西壶关太行山大峡谷景区为中国最美十大峡谷之一,但景区落石灾害频发,严重威胁景区安全运营.本文基于高精度地形信息与岩土体强度特性,采用坡度角分布方法开展区域尺度潜在落石源区识别,并引入岩体破坏敏感性指标定量描述潜在落石源区失稳概率.然后,利用经验模型Flow-R模拟落石运动扩散过程,获取落石的传播概率与能量分布情况.最后,提出落石危险性双因子评价模型实现落石危险性定量评估.获得主要结论如下:(1)研究区内潜在落石源区面积为25.7 km2(35.7％),主要以条带状分布于峡谷两侧陡壁.其中岩体破坏高敏感性区为3.3 km2.(2)研究区落石高危险区面积达3.22 km2,主要威胁景区内游客集散地与交通线路,尤其在S327荫林线红豆峡入口处落石危险性最高.(3)野外调查验证结果表明了应用坡度角分布方法识别潜在落石源区的高效性与准确性,提出的双因子评价模型可为峡谷区落石危险性评估提供快速解决方案.本文提出的"区域落石源区识别-源区失稳概率分析-落石危险性评估"的一整套技术方案能够为类似的高山峡谷区落石灾害早期识别及风险防控提供技术参考.

Although it is generally assumed that understanding the trigger factor leading to the transition from a progressive rock failure toward sudden and rapid events is better to risk management, the ability to identify triggering factors responsible for prehistoric catastrophic rock avalanches is still debated. Here we describe two rock avalanches (Ganqiu and Shuiqiu) in the Cuihua Mountain area of the Qinling Range, China, providing new mapping of rock avalanche source areas and deposits and absolute age constraint from cosmogenic Be-10 surface exposure dating. Results reveal that the Ganqiu rock avalanche is controlled by three sets of joints, causing the 380 m high ridge to collapse. Debris filled roughly the entire V-shaped valley and has a width ranging from 250 to 470 m, extending similar to 1260 m from the base of the cliff. The Shuiqiu rock avalanche was sourced near the summit of Cuihua Mountain from a cliff above 60 degrees that is mainly controlled by inherited fault and joints. The rock mass fell similar to 250 m as a giant blocky stream across the width of the valley floor, with the deposit extending similar to 300 m from the base of the cliff. Both events caused the large-scale collapse of ridge crests and developed into high-mobility rock avalanches with long runout. Cosmogenic Be-10 surface exposure dating from seven different parts of the deposits revealed nearly coincident ages for both rock avalanches, 10.0 +/- 0.9 ka for the Ganqiu rock avalanche and 9.5 +/- 1.2 ka for the Shuiqiu rock avalanche. Because this region was not affected by valley glaciation, rock avalanches triggering by paraglacial stress release can be excluded. Moreover, without clear evidence for specific climatic conditions in the Qinling area circa 9-10 ka, a climatic trigger for the Cuihua Mountain rock avalanches is equivocal. Instead, we find coincidence between the concurrent exposure ages and paleoseismic records from the nearby Qinling North Piedmont fault (QNF). This coincidence of ages, combined with the fact that the M-w 8.0 1556 CE Huaxian earthquake triggered numerous large rock falls in the Huashan Mountains at the eastern end of the Qinling Range, suggest that a large-magnitude earthquake centered in the middle-east section of QNF at ca. 8-11 ka may have triggered the Ganqiu and Shuiqiu rock avalanches.

Huge hazards are frequently caused by earthquake-induced rock avalanche. The study of dynamic response characteristics and failure mechanism of the rock slope in specific geological condition is a challenging issue in geotechnical engineering. In this paper, a shaking table test that reproduces the Shuiqiuchi rock avalanche was carried out to understand the dynamic response and failure mechanism of rock slope controlled by faults. The testing results show that when the dip angle of the fault is greater than a specific critical angle, part of the reflected and transmitted waves at the discontinuous interface change into sliding waves, resulting in a sudden change in the acceleration response at the fault. The peak acceleration amplification factor inside the model slope presents a significant three-stage trend. Peak horizontal acceleration amplification factor increases obviously with elevation, while peak vertical acceleration amplification factor increases slightly with elevation. The natural frequency curve of the slope model can be divided into three stages with a downward trend, which indicates that the dynamic characteristics of the model have changed. By comparing the shaking table test with the Shuiqiuchi rock avalanche prototype, the main failure mode of the rock slope with fault structure is found as follows: the slope crest first shows vertical tensile cracks under the seismic load, followed by cracking damage of the fragmented rock mass in the hanging wall of the fault, and finally sliding occurs along the fault surface. This research could provide references for the early-warning of granite avalanche, and offer the basic data and scientific support for the development of Qinling Mountain geological heritages.

我国是世界上受滑坡影响最大的国家之一,也投入了大量的人力物力开展区域性滑坡隐患探测工作.近年的政府工作表明,80％的滑坡发生在已圈定的隐患点范围外,80％的滑坡发生在防灾减灾工作条件相对薄弱的边远农村地区.为了解决这个困境,亟需:(1)厘清不同类型滑坡宜选用的广域探测技术,解决滑坡隐患广域探测的漏检问题;(2)突破社区协同滑坡防灾的难题,助力滑坡隐患探测和风险评估.本文将滑坡隐患分为4类:斜坡变形区、复活历史变形破坏区、稳定历史变形破坏区和潜在斜坡变形区,以便充分发挥多源遥感数据和技术的优势;进而提出一种"滑坡隐患广域探测-单体滑坡隐患风险评估-社区协同防灾"的多源遥感滑坡防灾技术框架.以青藏高原交通工程关键区段约10000 km2区域作为研究区,协同社区(如设计和建设单位)共识别出滑坡隐患263处,其中斜坡变形区249处,复活历史变形破坏区5处,稳定历史变形破坏区9处,并针对3个典型滑坡隐患进行风险定量评估和社区协同防灾.该多源遥感技术框架将有助于提高社区滑坡防灾的能力,也将直接服务于青藏高原交通工程的建设与运维.

青龙峡景区位于山西省壶关县太行山区东部,是太行山大峡谷国家地质公园的重要园区.青龙峡作为典型高山峡谷区,山地崩塌灾害极为发育,对景区旅游接待和居民生活构成威胁.为有效防控太行山区崩塌灾害,通过太行山青龙峡景区详细地质环境调查工作,掌握崩塌灾害发育规律,探讨崩塌成因和防治减灾对策.结果表明:青龙峡景区崩塌灾害发育在层状结构的硬岩高位边坡上,中小型崩塌更为常见;岩体破坏以错断式、倾倒式、滑移式和坠落式等4种破坏模式为主.峡谷区崩塌机理表现为多样的地层岩性组合孕崩、高陡的地形地貌育崩、复杂的岩体结构面控崩、岩溶和集中降水诱崩的四要素耦合崩塌成因机理.通过构建典型崩塌落石的Rockfall Analyst模型,分析危岩体崩塌的致灾边界,研判景区崩塌灾害的影响范围,针对青龙峡景区面临的地质安全问题,提出了景区崩塌灾害"风险区监测预警、隐患点工程治理"的防治对策.研究成果对山岳峡谷型景区和山区城镇的灾害防控具有借鉴价值.

太行山大峡谷位于山西省壶关县境内的南太行山区,历经亿万年的沧海桑田形成了以峡谷群、峰林石柱、河流瀑布、溶洞等为典型景观的大型高山峡谷景观系统,大峡谷现已建设成为"国家地质公园"和"5A"景区.同时,太行山大峡谷因地处我国第二、三阶梯的地表突变带,构造活动强烈,地表侵蚀严重,在山地特殊气候作用下崩塌灾害频发,时常损毁道路桥梁、破坏生活设施,并危及居民和游客安全,制约景区建设发展.本文立足大峡谷景区地质灾害详细调查,查明大峡谷内发育崩塌达318处,以高位小型岩质崩塌为主,主要分布于海拔700～1100 m之间,崩落高度平均120 m左右,最高可达300 m以上;崩塌多发育在断层带附近和软弱岩层处,沿峡谷两侧呈带状分布,以倾倒式和坠落式的破坏方式为主,具有明显的"群发、多发、复发"的特点.基于对大峡谷景区地形地貌、地层岩性、岩体结构、地表营力及人类活动等崩塌孕灾环境的分析,依据发育区位和致灾效应将崩塌划分为陡壁崩落带、梯状崩石链、碎裂崩滑带和水岸崩塌带4种类型;结合崩塌运动轨迹和对承灾体的效应归纳出崩落滚石型、崩链型、碎裂溃散型、落石涌浪型4种典型成灾模式,并分析提出景区安全防控的对策和建议.研究成果可为高山峡谷区的地质灾害防灾减灾、太行山区的景区开发规划和建设及地质环境保护提供借鉴.

为开展秦岭翠华山等大型花岗岩地震山崩的动力响应机制研究,研发配制用于振动台物理模型试验的花岗岩相似材料是该研究工作的基础.选取铁矿粉、石英砂、重晶石粉为骨料,石膏为调节材料,松香酒精溶液为黏结剂的相似材料配比方案,设计考虑4因素5水平的正交试验,并对试验结果进行极差分析及多元线性回归拟合,获得各因素对花岗岩相似材料物理力学性质的影响结果和相似材料配比经验方程.结果表明:花岗岩相似材料的密度随铁粉与重晶石粉占骨料比的增加而增大;随着黏结剂浓度的增加,花岗岩相似材料的抗压强度、弹性模量及黏聚力均显著增大;随着石膏含量的增加,密度、抗压强度及内摩擦角均减小.该试验得到的相似材料配比经验方程可以较好地为花岗岩相似材料或其他相似材料的配制提供参考.

Late Paleozoic volcanic rocks are well exposed in the Yining Block, NW China, and are predominately composed of andesites, rhyolites and volcaniclastics as well as minor basalts. Study of the petrology, whole-rock geochemistry and zircon U-Pb dating for the Early Carboniferous alkaline basalts from Wusun Mountain, western Yining Block, constrains their petrogenesis and tectonic evolution. The alkaline basalts consist mainly of plagioclases, mostly albite and labradorite, as well as clinopyroxenes and olivines; zircon U-Pb dating indicates their formation at ca. 350 Ma. Geochemically, the basaltic samples have low SiO2 contents, and high TiO2, Al2 O3 and alkaline contents, coupled with high Na2 O/K2 O ratios, displaying an alkaline basalt affinity. They show remarkable LILE enrichment and HFSE depletion. Meantime, these samples have relatively high TFe2 O3, MgO, and Mg# values as well as Ni and Cr, relatively high Sm/Yb and U/Th, suggesting origination from a mantle source metasomatized by slab fluids. They formed in a transitional tectonic setting from arc to intraplate, showing a typical affinity of back-arc basin basalts. The alkaline basalts were likely generated in a nascent back-arc extension setting resulting from slab rollback of the southern Tianshan oceanic lithosphere. A bidirectional subduction model seems more reasonable for the evolution of the southern Tianshan Ocean. These new data will provide a new tectonic model for Late Paleozoic tectonic evolution of the western Yining Block.

地震诱发山体崩塌常形成巨大的灾害,特定地形地质条件下山体地震动力响应特性及破坏机制研究是工程地质的重要难题.本文以秦岭地区具代表性的翠华山甘湫池花岗岩崩塌为研究对象,制作有效反映花岗岩工程地质结构的试验模型,开展大型振动台试验,研究山体地震动力响应规律和崩塌变形破坏机制.试验发现,边坡内部加速度放大系数随激振强度的增加呈现出显著的三阶段变化趋势;水平加速度响应呈现出随高程的增加而单调增大的特征,而竖直加速度响应随着高程的增加出现先增加后减小再增加的波动变化特征;边坡的固有频率变化曲线可以分为3个阶段,整体呈现下降的趋势,表明边坡动力特性发生变化;破坏后的边坡可以分为2个区域:后缘启动区和崩塌堆积区.边坡在地震激振作用下的破坏过程为地震波激振输入→坡体后缘形成拉张裂缝→裂缝向下扩展贯通→不稳定坡体滑动→堆积坡脚.反演了山体破坏的4个阶段:振动致裂阶段、高速启动阶段、撞击减速阶段和堆积阶段,结果与现场工程地质调查分析十分一致.研究翠华山甘湫池花岗岩崩塌的发育特征、成因机理和演化过程,研究成果对揭示秦岭北缘乃至秦岭地区崩塌形成机制、发育规律和灾害有效防控、地质遗迹开发和保护具有重要意义.

地震滑坡是严重的次生地质灾害,也是改变地球表层地貌形态的重要力量,对地震诱发滑坡的规模、数量、类型等研究是地震危险性评价的重要手段,也是认识地震地质灾害的主要方法和途径.位于西安市以南的秦岭山脉北麓中段发育有一条长约50 km的古滑坡群,且基本与山前秦岭北缘断裂带平行展布,普遍认为该古滑坡群可能是由于秦岭北缘断裂的强震活动所诱发,但对于诱发地震的震级大小和影响范围尚没有细致研究.本文通过利用资源3号卫星立体影像制作的高分辨率数值高程模型(DEM)和高分辨率多光谱遥感影像对秦岭北麓古滑坡区域进行了详细的解译工作,并结合对部分古滑坡体进行了野外调查,制作了详细秦岭北麓古滑坡分布图.结果表明:解译出了43处古滑坡,主要集中分布在70 km×10 km的范围内,总滑坡面积是16.57 km2.通过利用地震震级与滑坡面积频度分布的关系分析了诱发秦岭北麓古滑坡群的地震规模,得到了诱发秦岭北麓古滑坡群的地震震级应在7.6～8.1之间.并结合区域地震构造环境以及与现代地震诱发滑坡事件的对比,认为秦岭北麓具有发生7.5级以上地震的潜在能力.该研究对认识现今秦岭北麓古滑坡的成因提供了定量化的数据支持,也对理解秦岭北缘断裂的地震危险性具有重要的现实意义.

Luochuan Loess National Geopark does not only have a scientific research value regarding loess stratigraphy but also an ornamental value for its loess geomorphology. However, it is located in a region prone to geohazards, and the threats from loess geohazards should not be ignored. The famous loess-paleosol sequence section (Potou section) and some typical loess microtopography (e.g., loess column, loess wall, and loess bridge) have been introduced and appreciated. On the basis of fieldwork, some loess geohazards caused by earthquakes, rainfall, and freeze-thaw have been investigated. The three main factors of loess geohazards have been discussed, including loess vertical fissures, loess shear strength, and the freeze-thaw cycle. The results indicate that (1) loess vertical fissures can provide a path for surface water penetration and groundwater erosion, (2) a reduction in shear strength is an important cause for the occurrence of loess collapses induced by rainfall, and (3) repeated freeze-thaw cycles destroy loess’s integrity and lead to a reduction in shear strength. Finally, some protective measures such as monitoring of warning signs, reinforcement projects, drainage systems, and monitoring of geohazards have been implemented by the local government.

Xi’an is one of the oldest cities in China and has a civilization history of more than 3000 years. Recently, several large-scale rock avalanches have been found in peaks of the Qinling Mountains on the southern side of this city, and these rock avalanches might have a history as long as the city’s civilization. Among them, the Cuihua rock avalanche (CRA) located 30 kilometers to the south of Xi’an City is the most typical one, which, with characteristics of large scale, magnificent scene and good preservation, is called geological museum or miracle scenery of rock avalanche in China. Based on field investigation and geophysical prospecting, the authors studied such features of this rock avalanche as its geomorphology, volume, age, genetic mechanism and dynamics process. The results indicate that the volume of the rock avalanche is up to 1.8×107 m3 and its age is about 2900 years, suggesting that it resulted from the earthquake of 780 BC. The results of numerical simulation show that the whole failure process included four stages of starting up, accelerating, decelerating and accumulating; furthermore, the rock avalanche has some features of high speed and long distance. The study of the Cuihua rock avalanche has special importance for geological heritage protection, landslide research and tourism resources development.

The Cuihua Rock Avalanche, 30km south of Xi'an, China, is located within a marvelous geological landscape and was triggered by an ancient paleo-earthquake. The area is mainly characterized by cliffs, stone seas and a dammed lake (Shuiqiu Pool), with a total area of 5×105m2 and a volume of 1.8×107m3. Field investigations, historical records, dating methods and typical seismic profiles indicated that its occurrence could be correlated with an earthquake in 780BC that most likely triggered the landslide. The results also showed that a) the formation of the rock avalanche was associated with high-steep slope created by lifting of Qinling Mountain and cutting of rock fractures, and b) the high-steep slope and several preferred structural planes play an important role in controlling the slope instability. Based on conjectures, the failure process of the rock avalanche can be divided into four stages: the preliminary stage, the starting-up stage, the accelerating stage, and the accumulating stage.

It is very important to investigate geological relics landscapes for urban geological work.The Cuihua rock avalanche is a marvellous spectacle of seismic avalanches in China.Based on dynamic discrete element method,the dynamic response and failure process are simulated under a typical natural earthquake loading.The failure process of Cuihua rock avalanche is reproduced with the numerical simulation.The following results are obtained.Firstly,the amplification effect of velocity and acceleration is the reason of earthquake inertia force.The maximum magnification factor reaches 2.0 on the top of slope.Secondly,high speed and long run out are the characteristic of the rock avalanche.The results shown the maximum horizontal velocity reaches up to 44m·s-1 and the horizontal movement distance for some rocks reaches 460m at the front of the rock avalanche.Thirdly,the whole failure process include four stages: starting up stage,accelerating stage,decelerating stage and accumulation stage.