The Wulipo landslide, triggered by heavy rainfall on July 10, 2013, transformed into debris flow,resulted in the destruction of 12 houses, 44 deaths, and 117 missing. Our systematic investigation has led to the follow...The Wulipo landslide, triggered by heavy rainfall on July 10, 2013, transformed into debris flow,resulted in the destruction of 12 houses, 44 deaths, and 117 missing. Our systematic investigation has led to the following results and to a new understanding about the formation and evolution process of this hazard. The fundamental factors of the formation of the landslide are a high-steep free surface at the front of the slide mass and the sandstone-mudstone mixed stratum structure of the slope. The inducing factor of the landslide is hydrostatic and hydrodynamic pressure change caused by heavy continuous rainfall. The geological mechanical model of the landslide can be summarized as "instability-translational slide-tension fracture-collapse" and the formation mechanism as "translational landslide induced by heavy rainfall". The total volume of the landslide is 124.6×104 m3, and 16.3% of the sliding mass was dropped down from the cliff and transformed into debris flow during the sliding process, which enlarged 46.7% of the original sliding deposit area. The final accumulation area is found to be 9.2×104 m2. The hazard is a typical example of a disaster chain involving landslide and its induced debris flow. The concealment and disaster chain effect is the main reason for the heavy damage. In future risk assessment, it is suggested to enhance the research onpotential landslide identification for weakly intercalated slopes. By considering the influence of the behaviors of landslide-induced debris flow, the disaster area could be determined more reasonably.展开更多
The coordinated development of Beijing, Tianjin and Hebei has been elevated as China's important strategy. And, the priority in considering how to bring the maximum effect of their coordinated development into pla...The coordinated development of Beijing, Tianjin and Hebei has been elevated as China's important strategy. And, the priority in considering how to bring the maximum effect of their coordinated development into play is to delineate the spheres of urban influence with regard to the cities in the Beijing-Tianjin-Hebei Metropolitan Region. By building an evaluation index system of urban comprehensive strength, this paper applies the principal component analysis method to determine centrality strength of the cities, and the breakpoint theory and weighted Voronoi diagram to identify the spheres of urban influence in all central cities of the region. Results show that 13 central cities within the region greatly differ in strength, which can be classified into four tiers and that the spheres of urban influence do not have a high goodness of fit with administrative jurisdiction scope. Cities like Beijing, Tianjin, Shijiazhuang and Handan have larger spheres of urban, spheres of urban influence in Tangshan and Qinhuangdao are basically consistent with their administrative jurisdiction scopes, and seven cities including Langfang and Baoding have smaller spheres of urban influence. So according to these cities' comprehensive strength and spheres of influence, the region can be divided into five plates: Beijing, Tianjin, Shijiazhuang, Tangshan and Handan. The major influence factors for inconsistency between spheres of urban influence and spheres of jurisdiction include difference in urban administrative ranking, small number of central cities with weak strength, discrepancy in the number of counties under jurisdiction, unreasonable spheres of jurisdiction and diversity in topographical conditions. In order to solve the imbalance in the spheres of urban influence and those of jurisdiction and better facilitate the coordinated development of the region, it is advised to adjust administrative areas so as to obtain more optimized urban spatial layout and more reasonable urban scale hierarchy system.展开更多
基金funded by the key project of Sichuan province (Grand No. 2014SZ0163)the National Natural Science Foundation of China (Grant No. 41372301)the Key Deployment Project of Chinese Academy of Sciences (Grant No. KZZD-EW-05-01-02)
文摘The Wulipo landslide, triggered by heavy rainfall on July 10, 2013, transformed into debris flow,resulted in the destruction of 12 houses, 44 deaths, and 117 missing. Our systematic investigation has led to the following results and to a new understanding about the formation and evolution process of this hazard. The fundamental factors of the formation of the landslide are a high-steep free surface at the front of the slide mass and the sandstone-mudstone mixed stratum structure of the slope. The inducing factor of the landslide is hydrostatic and hydrodynamic pressure change caused by heavy continuous rainfall. The geological mechanical model of the landslide can be summarized as "instability-translational slide-tension fracture-collapse" and the formation mechanism as "translational landslide induced by heavy rainfall". The total volume of the landslide is 124.6×104 m3, and 16.3% of the sliding mass was dropped down from the cliff and transformed into debris flow during the sliding process, which enlarged 46.7% of the original sliding deposit area. The final accumulation area is found to be 9.2×104 m2. The hazard is a typical example of a disaster chain involving landslide and its induced debris flow. The concealment and disaster chain effect is the main reason for the heavy damage. In future risk assessment, it is suggested to enhance the research onpotential landslide identification for weakly intercalated slopes. By considering the influence of the behaviors of landslide-induced debris flow, the disaster area could be determined more reasonably.
基金Under the auspices of National Natural Science Foundation of China(No.41471126)
文摘The coordinated development of Beijing, Tianjin and Hebei has been elevated as China's important strategy. And, the priority in considering how to bring the maximum effect of their coordinated development into play is to delineate the spheres of urban influence with regard to the cities in the Beijing-Tianjin-Hebei Metropolitan Region. By building an evaluation index system of urban comprehensive strength, this paper applies the principal component analysis method to determine centrality strength of the cities, and the breakpoint theory and weighted Voronoi diagram to identify the spheres of urban influence in all central cities of the region. Results show that 13 central cities within the region greatly differ in strength, which can be classified into four tiers and that the spheres of urban influence do not have a high goodness of fit with administrative jurisdiction scope. Cities like Beijing, Tianjin, Shijiazhuang and Handan have larger spheres of urban, spheres of urban influence in Tangshan and Qinhuangdao are basically consistent with their administrative jurisdiction scopes, and seven cities including Langfang and Baoding have smaller spheres of urban influence. So according to these cities' comprehensive strength and spheres of influence, the region can be divided into five plates: Beijing, Tianjin, Shijiazhuang, Tangshan and Handan. The major influence factors for inconsistency between spheres of urban influence and spheres of jurisdiction include difference in urban administrative ranking, small number of central cities with weak strength, discrepancy in the number of counties under jurisdiction, unreasonable spheres of jurisdiction and diversity in topographical conditions. In order to solve the imbalance in the spheres of urban influence and those of jurisdiction and better facilitate the coordinated development of the region, it is advised to adjust administrative areas so as to obtain more optimized urban spatial layout and more reasonable urban scale hierarchy system.
