Current Articles

2021, Volume 32,  Issue 3

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2021, (3): 1-2.
Abstract:
The February 7 of 2021 glacier-rock avalanche and the outburst flooding disaster chain in Chamoli, India
Yueping YIN, Bin LI, Tiantian ZHANG, Meng WANG, Jiawei WAN, Xiaojie LIU, Yang GAO, Sainan ZHU
2021, 32(3): 1-8. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-01
Abstract:
On 7 Feb 2021, a high-location glacier-rock avalanche and dammed the river, and late caused outburst flooding disaster on the Rich Ganges River in northern Chamoli, India, that destroyed hydropower stations and bridge facilities more than 20 kilometers downstream, and claimed nearly 200 deaths. This paper uses multi-period high-resolution remote sensing images to compare and analyze the characteristics of the landslide source area and accumulation area before and after the high-location ice rock landslide disaster in the Ganges River Basin of Chamoli, India, and preliminarily discuss the movement process of the landslide. The results show that before 2013, the creep displacement of the avalanche landslide was small, and the cracks in the ice and snow cover on the surface were not obvious. From 2013 to 2017, the creep displacement of avalanche landslides increased significantly, and as many as 62 ice cracks of various sizes were visible in the ice and snow cover, with the longest being 513 m. Satellite images on February 5, 2021 showed that these ice cracks had been connected and penetrated, with a maximum width of 15 m, and they were unstable and damaged on February 7. According to the post-sliding remote sensing image, the collapsed landslide was cut from 4 sets of large structural surfaces in different directions, with an area of about 0.32 km2, an average thickness of about 70 m, and a volume of about 23×106 m3. The collapsed landslide body loses stability and disintegrates and moves down the valley with a debris flow at high speed. Due to terrain blocking, some debris particles accumulate in the rapid terrain change zone and form a barrier dam. After the barrier dam body breaks, a mountain torrent disaster is formed.
Types and development characteristics of high geological disasters in Chalonglongbaqu gully, Bomi , Tibet
Tiantian ZHANG, Yueping YIN, Bin LI, Kai HE, Meng WANG, Chaoying ZHAO, Xiaojie LIU
2021, 32(3): 9-16. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-02
Abstract:
Chalonglongbaqu gully is located on the right bank of Parlung Zangbo. The steeply changing topography has bred a large number of high-level geological disasters, threatening the downstream linear engineering. Therefore, this paper uses multi-source and multi-phase high-resolution remote sensing data to establish remote sensing interpretation signs of high-level geological disasters, determines the types of high-level geological disasters in the study area, and elaborates their development characteristics. The results show that the main types of geological disasters in the study area include high-level ice avalanches, high-level avalanches, and high-level landslides. Among them, there are 3 high-level ice avalanches, all of which are located on a slope with an altitude of 5000 m above the south slope of the upper reaches of the valley, with an area of more than 15×104 m2. There are 19 high-level avalanches, which are mostly distributed in the middle reaches of the valley and high and steep bank slopes on both sides of the upper main ditch. The northern slope is more than the southern slope. There are two high-level landslides located in the upper reaches of the valley, and the landslide is dominated by moraines. Under the action of strong earthquakes or heavy rainfall, the above-mentioned high-level geological disasters are prone to instability and blockage of ditch. After blocking the ditch, it is easy to induce secondary disaster chains such as floods and mudslides, which will cause the risk of blocking the river downstream of Parlung Zangbo.
Remote sensing interpretation and risk prediction analysis of Benduo high deformation body in Tibet
Tongyao WEI, Yueping YIN, Bin LI, Hongliang CHU, Yang GAO, Meng WANG, Chaoying ZHAO, Xiaojie LIU
2021, 32(3): 17-24. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-03
Abstract:
This article takes the Benduo high deformed body in the upper reaches of Yigong Zangbo as an example, combined with the methods of field ground survey, UAV integrated photographic survey, optical remote sensing dynamic investigation and numerical simulation prediction, the development characteristics and possibility of the Benduo high deformed body are analyzed. Predict and analyze the risk of forming a disaster chain. The results of the study are as follows: (1) The Benduo high-position deformable body is located in the fault, the rock mass is broken, the rock mass structural surface is developed, and the strength is low. At present, there are 12 small collapses and 64 cracks in the strong deformation of Benduo's high deformation body. (2) According to the interpretation results of InSAR, it is found that the Benduo high-position deformable body has two deformation areas. Among them, the BX1 deformation area is larger and the maximum deformation rate reaches 85 mm/a. Once it loses stability and slides, it has a higher risk of blocking the river. (3) Prediction and analysis of the risk of the deformed body after the instability shows that the Benduo high-level deformed body will block the Yigong Zangbu after the instability, the average thickness of the accumulation body is 90 m, and the backwater length of the dammed lake is 25 km. The backwater area formed by the blockage of the dam poses a higher threat to the downstream villages and towns after the failure of the upstream Zhongyu Village. (4) According to the risk characteristics of the dam body, the treatment plan for the excavation of the spillway tunnel is discussed.
Analysis on deformation characteristics of geological hazards in Ranwu Lake Estuary
Zhinan ZHAO, Bin LI, Yang GAO, Chaoying ZHAO, Xiaojie LIU, Meng WANG
2021, 32(3): 25-32. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-04
Abstract:
The continuous uplift of the Qinghai Tibet Plateau has led to frequent geological disasters in its surrounding areas. The complex geological background has created the characteristics of chain disaster development and high risk of river blocking in the Palongzangbu basin. In recent years, Ranwu Lake estuary, located in the Palongzangbu basin, has experienced severe geological deformation. In this paper, the risk material sources identification in 82 road class at Ranwu Lake are carried out by optical remote sensing and InSAR monitoring technology. It can be found that there are four risk source types in the study area: high-level ice debris, collapse, moraine and avalanche. Characteristics analysis and disaster risk assessment are carried out for each risk source, and based on the geological background of Ranwu Lake, this paper expounds the disaster causing factors and modes of risk material sources. Combined with the InSAR monitoring results. The slope body and its upper interpretation risk material sources areas on the right bank of Ranwu Lake estuary are divided into three high risk areas: 82 road class, Polong and Yalong, and the deformation characteristics are analyzed.
Remote sensing interpretation of development characteristics of high-position geological hazards in Sedongpu gully, downstream of Yarlung Zangbo River
Zhuang LI, Bin LI, Yang GAO, Meng WANG, Chaoying ZHAO, Xiaojie LIU
2021, 32(3): 33-41. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-05
Abstract:
Sedongpu gully is a branch gully on the left bank of the lower reaches of the Yarlung Zangbo River. It is located below the galabaire peak. It often accumulates abundant moraines and loose deposits every year. Affected by temperature, rainfall and earthquake, high-position geological disasters have occurred many times and caused the blockage of the Yarlung Zangbo River. Through field investigation, combined with Landsat and other multi-source and multi-phase remote sensing images and InSAR radar data, the development characteristics of high-position geological disasters in Sedongpu gully are analyzed, and the existing deformation bodies are interpreted and analyzed: There are many glaciers, collapses, landslides and ice lakes in sedongpu gully; In the past 20 years since 2001, there have been five high-position geological disasters blocking the mainstream of the Yarlung Zangbo River; There are 3 identified deformations and 2 suspected deformations in the upper part of the gully; According to the two high-position geological disasters occurred in 2018 in Sedongpu gully, it is considered that the provenance comes from one high-position rock avalanche area and three high-position ice avalanche areas. This paper provides preliminary data for the further study of high-position geological disasters in Sedongpu gully, and provides effective scientific ideas for the study of similar geological disasters.
Analysis of development characteristics of high-elevationchain geological hazard in Zelongnong, Nyingchi, Tibet based on high resolution image and InSAR interpretation
Jun LI, Hongliang CHU, Bin LI, Yang GAO, Meng WANG, Chaoying ZHAO, Xiaojie LIU
2021, 32(3): 42-50. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-06
Abstract:
Zelongnong Gully is located on the right bank of YarlungZangbo River in Milin County, Nyingchi, Tibet, which belongs to the post-earthquake affected area. Due to the steep terrain, abundant material sources and abundant water sources in the gully, the high-level geological disasters occurred frequently in the gully during 1950—2020, and the villages and bridges in the gully suffered serious threats for a long time. According to the field investigation and UAV aerial photography, combined with multi-stage remote sensing images and InSAR data, this paper interprets the types and quantity of high-risk sources in the formation area, as well as the movement and accumulation characteristics of loose deposits in the circulation area and accumulation area of Zelongnong Gully. The results show that at present, there are a large amount of glacial moraines of multistage and multi-period accumulation in the interface area between the formation area and the circulation area, and the fluidity is strong. The regional geological conditions, seismicity, meteorology and hydrology and other factors provide unstable source structure, good free space condition and storage platform, sufficient potential energy conversion condition and hydrodynamic condition for the occurrence of Zelongnong high-level chain geological disaster. The formation and evolution process of the high-level geological disaster chain in Zelongnong gully is summarized as follows: high ice collapse (rock collapse) - debris flow - mud-rock flow - blocking river and barrier dam (lake) - flood disaster, which has high vulnerability and high risk in the long term. In the later period, the monitoring, early warning and risk prevention and control of high-level geological disaster chain in Zelongnong Gully should be strengthened.
Characteristics, types, main causes and development of high-position geohazard chains along the Jiali fault zone, Tibet, China
Jiawei WAN, Hongliang CHU, Bin LI, Yang GAO, Kai HE, Zhuang LI, Yihao LI
2021, 32(3): 51-60. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-07
Abstract:
High-position geohazard chains are widely distributed along the Jiali fault zone, Tibet, China. They often induced severe flood disasters in the river basins of the Yigong Zangbu, Palong Zangbu, and the downstream of Yalu Zangbu, such as the famous Yigong, Guxiang, Jianmupuqu, and Midui high-position geohazard chains. Based on the field investigations and previously published data, these high-position geohazard chains are classified into 4 types: 1) high-position landslide-debris flow-dammed lake-flood, 2) high-position landslide-dammed lake-flood, 3) high-position debris flow-dammed lake-flood, 4) glacial lake outburst flood. The formation conditions of the high-position geohazard chains are analyzed from 4 aspects, that is 1) geological structures and earthquakes, 2) landscape and river system, 3) glacier, 4) meteorology. In the end, the main causes and development trends of these geohazard chains are discussed. We believe that the high-position geohazard chains would be more frequent along the Jiali fault zone, with the global warming and the enhancement of the human engineering activities.
Study on the development characteristics of post-fire debris flow and its early warning risk aversion in Zhongba Village, Xide County
Wanqing YIN, Tao JIN, Xiewen HU, Xichao CAO, Xiangbin YANG, Jian HUANG
2021, 32(3): 61-69. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-08
Abstract:
On May 7, 2020, a forest fire broke out in Zhongba Village, Luji Township, Xide County, Liangshan Yi Autonomous Prefecture, Sichuan Province, covering an area of about 6.7 km2. After the forest fire, the ash on the slope was about 2~6 cm thick, and the surface soil structure was disturbed. Under the heavy rainfall of about 20 min in the evening of June 4, the post-fire debris flow disaster broke out in the four gullies at the back mountain of Zhongba Village, which is a great threat to the 164 residents of 41 households in the gully mouth. Through remote sensing interpretation and field investigation, the fire intensity and deposit distribution characteristics of four gullies in the burned area are identified, the development characteristics of post-fire debris flow in Zhongba Village, Xide County are analyzed, and the risk assessment is carried out. Based on the real-time rainfall data obtained from group survey and group prevention, a set of early-warning and risk avoidance scheme for debris flow in mountain areas after fire is proposed, which has been verified by this example.
Investigation on slope rainfall threshold surface based on failure probablolity
Xisheng DENG, Yuan ZHANG, Yu TANG
2021, 32(3): 70-75. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-09
Abstract:
Rainfall is the main factor inducing slope deformation and instability, and the early warning and prediction of rainfall-triggered landslide has always been the core issue in the field of engineering. In this paper, the Monte Carlo method is introduced into the early warning and prediction of rainfall-triggered landslide. Firstly, based on the physical and mechanical parameters of rock and soil mass with normal distribution, the finite element numerical calculation model of slope is established, and the variation of slope stability coefficient under 9 different types of rainfall is analyzed. The results show that the incremental rainfall is particularly unfavorable to the stability of the slope, the uniform rainfall is the second, and the decreasing rainfallis the least. Secondly, the rainfall process is divided into antecedent and current rainfall, and the effective time of antecedent rainfall for current rainfall is 6 days. Finally, combined with the reliability theory, the failure probability Pf=10% is selected as the early warning index. By introducing the previous rainfall into the rainfall intensity-rainfall duration relation curve and taking it as the third coordinate axis, the curve is finally extended to the antecedent rainfall (A) - current rainfall (I) - rainfall duration (D) surface (A-I-D threshold surface). The research results have acertain guiding significance for the early warning and prediction of rainfall type slope.
Simplified calculation of settlement due to dewatering of phreatic aquifer in loess area
Changming HU, Cheng LIN
2021, 32(3): 76-83, 139. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-10
Abstract:
Focusing on the uneven settlement of surrounding buildings caused by deep foundation pit dewatering in loess area, this study analyzed the mechanism of ground settlement induced by foundation pit dewatering, deduced the simplified calculation formula of ground settlement caused by dewatering based on the layer-wise summation method and shear displacement method. First, the equation of the cone of depression was derived from Dupuit formula by ignoring group well effect and lateral displacement. The soil around the pit was divided into a drained zone and a saturated zone by the precipitation curve. Then introduce modification factor, and the effective stress increment caused by the reduction of pore water pressure in different loess layers was corrected. Finally, the constraint function of lateral friction located in soil-pile interface towards soil settlement was considered. The settlement at different distances from the dewatering well was calculated respectively, the actual settlement was the sum of the both. Instance calculates was performed based on an engineering example of foundation pit dewatering by finite element software Abaqus, and comparative analysis was carried out between numerical results and measured field data. The research results show that the position where the constraint effect of lateral friction became most significant was at the interface of soil and pile; the accuracy of settlement calculation in this paper was much higher than that of the normative method in the range of 1.5 times of precipitation depth, which can better predicted the ground settlement at different distances around the foundation pit in loess region during dewatering. The study could provide reference for calculating ground subsidence in similar phreatic aquifers.
Mechanism of the landslide deformation due to drilling of boreholes:A case study of Fanshantou landslide at Songyang County of Zhejiang Province
Xiaojuan LUO
2021, 32(3): 84-90. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-11
Abstract:
Fanshantou landslide in Songyang is a medium-sized soil landslide with two sliding belts. The geological conditions are complex. After the first discovery in 2010, it has been in a period of peristaltic deformation. In July 2018, it began to adopt siphon drainage engineering. During the process of treatment and construction, a large amount of drilling water was lost, resulting in a cumulative deformation of 57 to 74 mm in the depth of the landslide until the oblique hole was cut, and the maximum width of the landslide surface crack reached 17.5 mm. After stopping drilling and starting siphon drainage, the landslide cracks stopped expanding, and the deep area displacement was controlled within 1 mm. Based on the monitoring data of the emergency rescue, this paper analyzes the bidirectional response process of moving landslide to the changes of groundwater flow field, and analyzes the mechanism of the response process by means of hydraulics and effective stress principle. It is concluded that groundwater runoff permeability must be fully considered in design calculation and engineering practice, and can not be ignored blindly.
Application research of unmanned aerial vehicle remote sensing detection for 3D terrain modeling and feature analysis of debris flow gullies in complex mountainous area of Dongchuan
Rui BI, Shu GAN, Raobo LI, Lin HU
2021, 32(3): 91-100. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-12
Abstract:
Taking the debris flow gully of the tributary of the Dabaini River on the left bank of the middle reaches of the Xiaojiang River Basin in Dongchuan District, Yunnan Province as the research object, the surface landform data of the debris flow gully was collected by Unmanned Aerial Vehicle (UAV) remote sensing technology. This paper proposes a method of extracting the control points of the same-named objects in combination with the ground three-dimensional laser scanning modeling data to realize the absolute orientation of UAV image data. Through Smart3D image data processing, a three-dimensional terrain model of the study area is constructed to obtain digital orthophoto map (DOM), digital surface model (DSM) and high-density matching point cloud. The point cloud data is processed using the Irregular Triangle Network progressive encryption technology in PhotoScan software to obtain a digital elevation model (DEM) with a resolution of 0.5 m. Combined with the relevant terrain analysis modules in ArcGIS and Cloud Compare, the terrain characteristics of this section of debris flow valley area can be analyzed. The technical route and method used in the modeling and analysis of debris flow gully terrain based on UAV remote sensing are of important empirical case reference value and practical guiding significance for qualitative and quantitative detection of geological disasters in the plateau complex mountain area and their monitoring and prevention.
Design method of anchor pier type active protective net on fractured rock slopes
Bing WU, Yao LIANG, Xiaoyan ZHAO, Xiaobo TANG, Xiaochun WU, Tiancheng LUO
2021, 32(3): 101-108. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-13
Abstract:
The shallow surface rock mass of the high and steep rock slopes in the existing highway (railway) projects, especially with severe weathering slope rock mass, is mostly cataclastic. After the traditional SNS active protective net is adopted to reinforce the slope, the rock slope has been locally unstable or subject to overall instability. Therefore, it is necessary to improve the structure and the corresponding design method for the reinforcement and protection of cataclastic rock slope. A new type of combination structure of anchor-pier active protection net as well as the stress calculation and design method is put forward, which can effectively prevent the destruction of cataclastic rock slope surface and ensure the overall stability of the slope. It can be seen from the engineering application that the combined protective structure has good reinforcing effect on the cataclastic rock slope, and it could be applied in the engineering construction.
Research on function model of lime-improved high liquid limit soil strength characteristics
Hongkun HU, Zhushan SHAO
2021, 32(3): 109-117. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-14
Abstract:
In view of the large number of high liquid limit soil abandonment problems along the roadbed of the Liyu Expressway in Guangxi, quick lime was used to improve the high-liquid limit soil. the high-liquid limit soil samples with different initial water content and different lime content from the spoil field were used to conduct lateral compression test and fast shear test, and the basic elementary mathematical function model was used to fit different saturation states and different initial water content. The effect of lower lime content on the compression characteristics and shear strength of the specimen is tested. The results show that: (1) The compression coefficient of high liquid limit soil decreases exponentially with the increase of lime content; (2) the cohesion and internal friction angle of the specimens in different saturated states change with the increase of lime content in the form of quadratic function; (3) High liquid limit soil has water sensitivity. The moisture content corresponding to the shear strength is 3%~6% higher than the moisture content corresponding to the maximum dry density of the compaction test; (4) When the initial moisture content is lower than 26.73%, it is recommended that the lime content is not less than 6%, otherwise the lime content of the modified high liquid limit soil is not less than 8%, which can be achieved under the premise of meeting economics and better improvement effect.
Exploring early warning and forecasting of meteorological risk of landslide and rockfall induced by meteorological factors by the approach of machine learning
Yangchun LI, Qianyun LIU, Xiao LI, Tianhong GU, Nan ZHANG
2021, 32(3): 118-123. doi: 10.16031/j.cnki.issn.1003-8035.2021.00-15
Abstract:
In the traditional methods of meteorological risk early warning and forecasting, the vulnerability factors of disaster bearing bodies are ignored when classifying the meteorological risk level, and the meteorological risk prediction level is relatively high, which leads to the high air report rate in high-level risk areas. Based on this, a method of early warning and forecasting of meteorological risk of landslide and collapse geological disasters based on machine learning is proposed. By using the information quantity method, the influence degree of meteorological factors is analyzed, and the coordinate point, rainfall and prone level are selected as input nodes of machine learning artificial neural network to judge whether geological disaster occurs; for the area of ground damage, the meteorological cause sub index is calculated according to the influence degree. Combined with the potential degree of geological disaster and vulnerability of disaster bearing body, the meteorological risk warning index is determined, divide the warning and forecast level, and complete the forecast of geological disaster meteorological risk. The experimental results show that the proposed method can effectively reduce the three-level forecast air report rate and the fourth level air alarm rate, and improve the precision of the early warning forecast.
Development and distribution rules of geohazards in Diexi- Songpinggou scenic area in a meizoseismal area
Chenglin MU, Zhaohui XI, Xiangjun PEI, Shenghua CUI
2021, 32(3): 124-130. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-16
Abstract:
The Songpinggou scenic area in Diexi was taken as the study area and there are 107 geological disasters were found, including 82 collapses and 25 landslides in this meizoseismal area. The influencing factors of the development and distribution of geological disasters include: original slope, development elevation, slope structure, water system distance and fault zone distance. The number and scale of disasters are distributed in the slope of 30 ° to 50 ° and the number and scale of disasters are large; the number of disasters with elevation of 2200~3400 m accounts for 42.5% of the total, especially the elevation of 2600~3000 m accounts for 42.5% of the total; the number and scale of geological disasters developed in oblique slope are relatively large, followed by consequent slope and reverse slope; the maximum influence distance of water system on disaster is 4.0 km, in which the range of 0~1 km is within. The results show that the geological disasters are developed and large-scale; the distribution of geological disasters along the seismic fault zone is sub "string beads", and the most significant development is in the range of 0~4.0 km, which conforms to a certain fitting law. Based on the statistical analysis, the main influencing factors of the development of geological disasters in the Songpinggou scenic area of Diexi are determined, and the distribution rules are systematically summarized, which provides scientific basis and reference for the infrastructure construction and disaster prevention and mitigation in the study area.
Characteristics and spatial-temporal distribution law of karst collapse in Sanzhou basin in Gaoming District of Foshan City, Guangdong Province
Qingding HAN, Xiyi LUO, Shouyong YI, Jie ZOU
2021, 32(3): 131-139. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-17
Abstract:
Sanzhou basin in Gaoming District of Foshan City is selected as the research area. data of regional geology, geological structure, engineering geology, hydrogeology, environmental geology and historical geological disasters in the study area are collected systematically, the characteristics of karst collapse are found out through field investigation. And the spatial-temporal distribution law is analyzed. The results show that: (1)The scale of karst collapse is mainly small, its plane shape features are mainly circular and quasi circular, and its profile shape features are mainly funnel-shaped. With the increase of the overburden thickness, the profile shape features of karst collapse generally change from circular-shape to jar-shape to funnel-shape and then to disc-shape. (2)The spatial distribution of karst collapse is affected by stratum lithology, geological structure, overburden thickness and its structure, groundwater runoff and human engineering activities. (3)The temporal distribution of man-made karst collapse is closely related to mining activity and drilling construction. The temporal distribution of karst collapse induced by nature is mainly during the alternate period of drought and flood (especially from March to April).
Risk zonation on the submarine geological hazards in Bohai Sea
Yupeng SONG, Yongfu SUN, Xing DU, Xiaoyu LIU, Zhenhao WANG, Chenglin CAO
2021, 32(3): 140-146. doi: 10.16031/j.cnki.issn.1003-8035.2021.03-18
Abstract:
This paper established the system of assessment in dex for regionalization of geological hazards in Bohai Sea with four aspects of hydrodynamic condition, engineering geological environment, disaster geological conditions and human engineering activities based on analytic hierarchy process, eight evaluation factors selected and the distribution characteristics of each geological hazard evaluation factor which were discussed in detail. The integrated geological disaster evaluation and regionalization were carried out combined with qualitative analysis and quantitative calculation. The risk level of submarine geological hazards in Bohai Sea are divided into four types: high, medium-high, medium-low and low.The study results can provide scientific basis for engineering construction and hazard prevention in Bohai Sea area.