| Influenced by the collision between Indian plate and Asian plate,Bailong river basin in Gansu province has been pressed by two main forces,one is from the east Kunlun fault zones,another is from the fault zones at northern edge of western Qinling Mountain.For these reasons,the faults are well-developed and the main faults include 4 faults,respectively,Lintan-Tanchang fault,Guangganshan-Dieshan fault,Diebu-Bailongjiang fault and Wenxian-kangxian fault in the area.The well-developed faults control the distributions of physiognomy?rock and underground water which are the main factors of landslide.In addition,the high mountains and the narrow valleys influenced by the tectonic movement not only be used for the formation of local rain,but also controls the distribution of population along the river valley.These show that the same distribution between the landslide controlled by the fault and the population aggravates the landslide disaster extent,and the area becomes one of the four areas in China most severely affected by landslide and debris flow hazards.So Bailong river basin in Gansu province was chosen to be the research area,and the theme was the development of landslides dominated by Neotectonics.This paper includes the three main aspects,the characteristic of the active tectonic belts,the controlled role of the active faults to the landslide and the postseismic effect of “5.12”earthquake.Firstly,based on the previous literature,the new tectonic stress field and the velocities of the main tectonic belts were analyzed by Scheidegger method and InSAR technique in this paper.Secondly,Indoor and outdoor survey,fractal theory and elemental analysis were applied to discuss the control role of the active faults.Thirdly,the small typical river basin(Goulinping river basin)and landslide(Goulinping landslide)were chosen to study the postseismic effect of “5.12”earthquake by many ways.And the main achievements were as follows:(1)The neotectonic stress field was calculated by the geomorphology-drainage method.The main stresses were not consistent,there was a clockwise deflection from northwest to southeast and the value was from NW39.8° to NE74.8°?(2)Using InSAR technology,the velocities of main faults ware got.The velocities in LOS of Lintan-Tanchang fault,Guangaishan-Dieshan fault,Diebu-Bailong fault and Wenxian-Kangxian fault were respectively(3.5 mm/a,0.9 mm/a),(2.6 mm/a,0.1 mm/a),(4.6 mm/a,2.1 mm/a),(3.5 mm/a,0.9 mm/a)and(4.1 mm/a,-0.6 mm/a),and the relative velocities were 2.6 mm/a,2.5 mm/a,2.5 mm/a and 4.7 mm/a.The tectonic activity intensity in northwest was higher than that in southeast and the dividing point was Lianghekou.(3)The control roles of the fault to the landslide can be divided into three aspects,the fault controls the distribution of the landslide,the fault controls the morphological characteristics of the huge landslide and the fault controls the location of the sliding zone.And the geological model of landslide hazard formation has 2 types,subparallel landslide and subvertical with fault.(4)Wenchuan earthquake had an obvious influence on the study area,the relative velocity was from 8 mm/a to 11.5 mm/a between the hanging wall and footwall of Diebu-Bailongjiang fault in Goulinping river basin.The number of landslide affected by Wenchuan earthquake increased dramatically and the increased rate decreased gradually along time.(5)The water content of Goulinping landslide were influenced by bedrock fissure water and rainfall,and the distribution and water content were varied as the precipitation process.Rainstorm had a serious effect on the soil in the surface,and there was a close relationship between the precipitation process and the slide process. |
PDF Full Text Request