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Analysis on Two Typical Landslide Hazard Phenomena in The Wenchuan Earthquake by Field Investigations and Shaking Table Tests.

Yang C, Zhang J, Liu F, Bi J, Jun Z - Int J Environ Res Public Health (2015)

Bottom Line: Considering the above disaster phenomena, the reasons are analyzed based on shaking table tests of one-sided, two-sided and four-sided slopes.The analysis results show that: (1) the amplifications of the peak accelerations of four-sided slopes is stronger than that of the two-sided slopes, while that of the one-sided slope is the weakest, which can indirectly explain the phenomena that the damage is most serious; (2) the amplifications of the peak accelerations gradually increase as the slope angles increase, and there are two inflection points which are the point where the slope angle is 45° and where the slope angle is 50°, respectively, which can explain the seismic phenomenon whereby landslide hazards mainly occur on the slopes whose slope angle is bigger than 45°.The amplification along the slope strike direction is basically consistent, and the step is smooth.

View Article: PubMed Central - PubMed

Affiliation: School of Civil Engineering, Key of Transportation Tnuuel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China. yangchangwei56@163.com.

ABSTRACT
Based on our field investigations of landslide hazards in the Wenchuan earthquake, some findings can be reported: (1) the multi-aspect terrain facing empty isolated mountains and thin ridges reacted intensely to the earthquake and was seriously damaged; (2) the slope angles of most landslides was larger than 45°. Considering the above disaster phenomena, the reasons are analyzed based on shaking table tests of one-sided, two-sided and four-sided slopes. The analysis results show that: (1) the amplifications of the peak accelerations of four-sided slopes is stronger than that of the two-sided slopes, while that of the one-sided slope is the weakest, which can indirectly explain the phenomena that the damage is most serious; (2) the amplifications of the peak accelerations gradually increase as the slope angles increase, and there are two inflection points which are the point where the slope angle is 45° and where the slope angle is 50°, respectively, which can explain the seismic phenomenon whereby landslide hazards mainly occur on the slopes whose slope angle is bigger than 45°. The amplification along the slope strike direction is basically consistent, and the step is smooth.

No MeSH data available.


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The peak acceleration amplification coefficient in the slope direction.
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ijerph-12-09181-f019: The peak acceleration amplification coefficient in the slope direction.

Mentions: Based on the above formulas, we put the related parameters into the formulas, and then the results can be obtained, as shown in the following: FP/ES is a negative number, but FS/ES is a positive number. That fully shows that the phase of the input SV wave is consistent with that of the reflected SV wave, but is opposite to that of the reflected P wave. It leads to the fact that the vibration component of the input SV wave and the reflected SV wave in the direction L are consistent with that in the direction N, but that of the input SV wave and reflected P wave in the direction L is opposite to that in the direction N. At the same time, the components of the input SV wave in the direction Land N is Es and 0, respectively. That of reflected SV wave in the direction Land N is (ES + FS)sin(2θ − 90°) and (ES + FS)cos(2θ − 90°), respectively. That of reflected P wave in the direction Land N is Fpcos(2θ1 − 90°) and Fpsin(2θ1 − 90°), respectively. Therefore, the total vibration components in the direction L and N are Es + (ES + FS)sin(2θ − 90°) + Fpcos(2θ1 − 90°) and (ES + FS)cos(2θ − 90°) + Fpsin(2θ1 − 90°). In addition, with the increase of incident angle, the reflection angle of the SV wave gradually increases and the vibration direction moves to the direction L. However, the reflection angle θ1 of the P wave gradually increases and the vibration component in the direction L gradually decreases. So both (ES + FS)sin(2θ − 90°) + Fpcos(2θ1 − 90°) and (ES + FS)cos(2θ − 90°) + Fpsin(2θ1 − 90°) gradually increase. Therefore, with the increase of slope angle, the amplification of acceleration in the directions L and N gradually increases. A similar conclusion about the amplification in the direction M can be obtained by using the above thinking. In order to reveal the effect of slope angle on the acceleration amplification clearly, only the measuring point at the position H/4 is selected for analysis, and the results are shown in Figure 18, Figure 19 and Figure 20.


Analysis on Two Typical Landslide Hazard Phenomena in The Wenchuan Earthquake by Field Investigations and Shaking Table Tests.

Yang C, Zhang J, Liu F, Bi J, Jun Z - Int J Environ Res Public Health (2015)

The peak acceleration amplification coefficient in the slope direction.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4555273&req=5

ijerph-12-09181-f019: The peak acceleration amplification coefficient in the slope direction.
Mentions: Based on the above formulas, we put the related parameters into the formulas, and then the results can be obtained, as shown in the following: FP/ES is a negative number, but FS/ES is a positive number. That fully shows that the phase of the input SV wave is consistent with that of the reflected SV wave, but is opposite to that of the reflected P wave. It leads to the fact that the vibration component of the input SV wave and the reflected SV wave in the direction L are consistent with that in the direction N, but that of the input SV wave and reflected P wave in the direction L is opposite to that in the direction N. At the same time, the components of the input SV wave in the direction Land N is Es and 0, respectively. That of reflected SV wave in the direction Land N is (ES + FS)sin(2θ − 90°) and (ES + FS)cos(2θ − 90°), respectively. That of reflected P wave in the direction Land N is Fpcos(2θ1 − 90°) and Fpsin(2θ1 − 90°), respectively. Therefore, the total vibration components in the direction L and N are Es + (ES + FS)sin(2θ − 90°) + Fpcos(2θ1 − 90°) and (ES + FS)cos(2θ − 90°) + Fpsin(2θ1 − 90°). In addition, with the increase of incident angle, the reflection angle of the SV wave gradually increases and the vibration direction moves to the direction L. However, the reflection angle θ1 of the P wave gradually increases and the vibration component in the direction L gradually decreases. So both (ES + FS)sin(2θ − 90°) + Fpcos(2θ1 − 90°) and (ES + FS)cos(2θ − 90°) + Fpsin(2θ1 − 90°) gradually increase. Therefore, with the increase of slope angle, the amplification of acceleration in the directions L and N gradually increases. A similar conclusion about the amplification in the direction M can be obtained by using the above thinking. In order to reveal the effect of slope angle on the acceleration amplification clearly, only the measuring point at the position H/4 is selected for analysis, and the results are shown in Figure 18, Figure 19 and Figure 20.

Bottom Line: Considering the above disaster phenomena, the reasons are analyzed based on shaking table tests of one-sided, two-sided and four-sided slopes.The analysis results show that: (1) the amplifications of the peak accelerations of four-sided slopes is stronger than that of the two-sided slopes, while that of the one-sided slope is the weakest, which can indirectly explain the phenomena that the damage is most serious; (2) the amplifications of the peak accelerations gradually increase as the slope angles increase, and there are two inflection points which are the point where the slope angle is 45° and where the slope angle is 50°, respectively, which can explain the seismic phenomenon whereby landslide hazards mainly occur on the slopes whose slope angle is bigger than 45°.The amplification along the slope strike direction is basically consistent, and the step is smooth.

View Article: PubMed Central - PubMed

Affiliation: School of Civil Engineering, Key of Transportation Tnuuel Engineering, Ministry of Education, Southwest Jiaotong University, Chengdu 610031, China. yangchangwei56@163.com.

ABSTRACT
Based on our field investigations of landslide hazards in the Wenchuan earthquake, some findings can be reported: (1) the multi-aspect terrain facing empty isolated mountains and thin ridges reacted intensely to the earthquake and was seriously damaged; (2) the slope angles of most landslides was larger than 45°. Considering the above disaster phenomena, the reasons are analyzed based on shaking table tests of one-sided, two-sided and four-sided slopes. The analysis results show that: (1) the amplifications of the peak accelerations of four-sided slopes is stronger than that of the two-sided slopes, while that of the one-sided slope is the weakest, which can indirectly explain the phenomena that the damage is most serious; (2) the amplifications of the peak accelerations gradually increase as the slope angles increase, and there are two inflection points which are the point where the slope angle is 45° and where the slope angle is 50°, respectively, which can explain the seismic phenomenon whereby landslide hazards mainly occur on the slopes whose slope angle is bigger than 45°. The amplification along the slope strike direction is basically consistent, and the step is smooth.

No MeSH data available.


Related in: MedlinePlus