On May 12, 2008, a magnitude 8.0 earthquake hit Wenchuan County, Sichuan Province resulted in great loss of life and properties.Besides, abundant landslides and slope failures were triggered in the most seriously hit ...On May 12, 2008, a magnitude 8.0 earthquake hit Wenchuan County, Sichuan Province resulted in great loss of life and properties.Besides, abundant landslides and slope failures were triggered in the most seriously hit areas and caused disastrous damages to infrastructures and public facilities.Moreover, abundant unstable slopes caused by the quake have the potential to cause damages for a considerable long period of time.The variety of these slopes and the corresponding treatments are connected with the topographical and geological conditions of the sites.It is decided to document and identify some of these major slope instabilities caused by the earthquake and their treatments.The paper shows the condition of a road in Dujiangyan through in situ explorations.The case history showed significant implications to the reconstruction of the quake-hit regions and future disaster prevention and management works.展开更多
Debris flows and landslides, extensively developing and frequently occurring along Parlung Zangbo, seriously damage the Highway from Sichuan to Tiebt(G318) at Bomi County. The disastrous debris flows of the Tianmo Wat...Debris flows and landslides, extensively developing and frequently occurring along Parlung Zangbo, seriously damage the Highway from Sichuan to Tiebt(G318) at Bomi County. The disastrous debris flows of the Tianmo Watershed on Sept. 4, 2007, July 25, 2010 and Sept. 4, 2010, blocked Parlung Zangbo River and produced dammed lakes, whose outburst flow made 50 m high terrace collapse at the opposite bank due to intense scouring on the foot of the terrace. As a result, the traffic was interrupted for 16 days in 2010 because that 900 m highway base was destructed and 430 m ruined. These debris flows were initiated by the glacial melting which was induced by continuous higher temperature and the following intensive rainfall, and expanded by moraines along channels and then blocked Parlung Zangbo. At the outlet of watershed,the density, velocity and peak discharge of debris flow was 2.06 t/m3, 12.7 m/s and 3334 m3/s, respectively. When the discharge at the outlet and the deposition volume into river exceeds 2125 m3/s and 126×103 m3, respectively, debris flow will completely blocked Parlung Zangbo. Moreover,if the shear stress of river flow on the foot of terrace and the inclination angel of terrace overruns 0. 377 N/m2 and 26°, respectively, the unconsolidated terrace will be eroded by outburst flow and collapse. It was strongly recommended for mitigation that identify and evade disastrous debris flows, reduce the junction angel of channels between river and watershed, build protecting wall for highway base and keep appropriate distance between highway and the edge of unconsolidated terrace.展开更多
Since the Wenchuan earthquake in China on May 12th, 2008, highways in earthquake-affected areas have been frequently interrupted by debris flows. We analyzed the hazard effect modes and damage processes along highways...Since the Wenchuan earthquake in China on May 12th, 2008, highways in earthquake-affected areas have been frequently interrupted by debris flows. We analyzed the hazard effect modes and damage processes along highways and developed three key indexes, scale of debris flows, deposits on highways and river blockage, to describe quantitatively the highway disasters. By combining the empirical methods and the actual terrain conditions, we proposed new methods to determine the value of hazard indexes. In addition, we used the economic value and resistance of highway as vulnerability assessment indexes, then determined the specific subindexes for the subgrade, bridges and culverts, and developed a way for the quantified vulnerability zoning. Moreover, we proposed the assessment and mapping methods for highway risk. The risk is described into 5 grades： extremely low risk, low risk, middle risk, high risk and extremely high risk. We applied these methods in a case study carried out on provincial highway S3o3 from Yingxiu Town to Wolong Town, in Wenchuan County. Analysis of debris flow risk for the whole highway, showed that the total length of highway in extremely low risk area was 28.26 km, 4.83 km in low risk area, 8.0 km in middle risk area, 3.65 km in high risk area, and 3.06 km in extremely high risk area. The assessment results are consistent with the field survey data which reflected the disaster situation. This risk method can be used objectively to evaluate the debris-flow risk along highways, and is useful for highway reconstruction in mountainous areas suffering from active debris flows.展开更多
基金supported by the 973 Program of China (Grant No. 2008CB425803the Open Fund of the Key Laboratory of Marine Geology and Environment, China Academy of Sciences (Grant No. MGE2008KG04)the Open Fund of the Key Laboratory of Mountain Hazards and Surface Process, CAS.
文摘On May 12, 2008, a magnitude 8.0 earthquake hit Wenchuan County, Sichuan Province resulted in great loss of life and properties.Besides, abundant landslides and slope failures were triggered in the most seriously hit areas and caused disastrous damages to infrastructures and public facilities.Moreover, abundant unstable slopes caused by the quake have the potential to cause damages for a considerable long period of time.The variety of these slopes and the corresponding treatments are connected with the topographical and geological conditions of the sites.It is decided to document and identify some of these major slope instabilities caused by the earthquake and their treatments.The paper shows the condition of a road in Dujiangyan through in situ explorations.The case history showed significant implications to the reconstruction of the quake-hit regions and future disaster prevention and management works.
基金supported by the Key Program of National Natural Science Found of China(Grant No.41030742)the Grand Program of National Natural Science Found of China(Grant No.41190084)
文摘Debris flows and landslides, extensively developing and frequently occurring along Parlung Zangbo, seriously damage the Highway from Sichuan to Tiebt(G318) at Bomi County. The disastrous debris flows of the Tianmo Watershed on Sept. 4, 2007, July 25, 2010 and Sept. 4, 2010, blocked Parlung Zangbo River and produced dammed lakes, whose outburst flow made 50 m high terrace collapse at the opposite bank due to intense scouring on the foot of the terrace. As a result, the traffic was interrupted for 16 days in 2010 because that 900 m highway base was destructed and 430 m ruined. These debris flows were initiated by the glacial melting which was induced by continuous higher temperature and the following intensive rainfall, and expanded by moraines along channels and then blocked Parlung Zangbo. At the outlet of watershed,the density, velocity and peak discharge of debris flow was 2.06 t/m3, 12.7 m/s and 3334 m3/s, respectively. When the discharge at the outlet and the deposition volume into river exceeds 2125 m3/s and 126×103 m3, respectively, debris flow will completely blocked Parlung Zangbo. Moreover,if the shear stress of river flow on the foot of terrace and the inclination angel of terrace overruns 0. 377 N/m2 and 26°, respectively, the unconsolidated terrace will be eroded by outburst flow and collapse. It was strongly recommended for mitigation that identify and evade disastrous debris flows, reduce the junction angel of channels between river and watershed, build protecting wall for highway base and keep appropriate distance between highway and the edge of unconsolidated terrace.
基金supported by the National Natural Science Foundation of China (NSFC)(Grant No.41030742)the projects of National Basic Research Program of China (973 Program)(Grant No.2011CB409902)
文摘Since the Wenchuan earthquake in China on May 12th, 2008, highways in earthquake-affected areas have been frequently interrupted by debris flows. We analyzed the hazard effect modes and damage processes along highways and developed three key indexes, scale of debris flows, deposits on highways and river blockage, to describe quantitatively the highway disasters. By combining the empirical methods and the actual terrain conditions, we proposed new methods to determine the value of hazard indexes. In addition, we used the economic value and resistance of highway as vulnerability assessment indexes, then determined the specific subindexes for the subgrade, bridges and culverts, and developed a way for the quantified vulnerability zoning. Moreover, we proposed the assessment and mapping methods for highway risk. The risk is described into 5 grades： extremely low risk, low risk, middle risk, high risk and extremely high risk. We applied these methods in a case study carried out on provincial highway S3o3 from Yingxiu Town to Wolong Town, in Wenchuan County. Analysis of debris flow risk for the whole highway, showed that the total length of highway in extremely low risk area was 28.26 km, 4.83 km in low risk area, 8.0 km in middle risk area, 3.65 km in high risk area, and 3.06 km in extremely high risk area. The assessment results are consistent with the field survey data which reflected the disaster situation. This risk method can be used objectively to evaluate the debris-flow risk along highways, and is useful for highway reconstruction in mountainous areas suffering from active debris flows.
