日本地球惑星科学連合2022年大会

講演情報

[E] 口頭発表

セッション記号 H (地球人間圏科学) » H-DS 防災地球科学

[H-DS07] 地すべりおよび関連現象

2022年5月24日(火) 13:45 〜 15:15 201B (幕張メッセ国際会議場)

コンビーナ:千木良 雅弘(公益財団法人 深田地質研究所)、コンビーナ:王 功輝(京都大学防災研究所)、今泉 文寿(静岡大学農学部)、座長:今泉 文寿(静岡大学農学部)

14:45 〜 15:00

[HDS07-16] Investigation of Shallow Subsurface Structures on Slope using Surface Wave Method

*森藤 遥平1平田 康人1窪田 健二1 (1.一般財団法人 電力中央研究所)

キーワード:表層崩壊、表面波探査

Soil thickness is a significant index to evaluate slope stability. The thickness is usually estimated by dynamic penetration resistance obtained with a standard or simple corn penetrometer. However, much time and labor is associated with conducting the measurement on slopes. Surface wave methods have been used to illustrate S-wave velocity structures relating penetration resistant values, but it is rarely applied on slopes. To verify the effectiveness on slopes, we performed a surface wave method on a hillslope in Yasuura, Kure city. The study site is underlain by the Takada Rhyolite and experienced many shallow landslides due to heavy rainfall in July 2018. Six survey lines were arranged on the slope with 1 m receiver spacing and 1 m source spacing. Three lines were set along the uniformly inclined slope and the rest were arranged to be orthogonal to the three lines. The common midpoint cross correlation method (CMPCC) and the multichannel analysis of surface waves (MASW) were applied to calculate dispersion curves. S-wave velocity was estimated from the dispersion curves using a nonlinear least square method. In the result of the surface wave analysis, a boundary of S-wave velocity was appeared at 2 -3 m depth on the slope. The low velocity area (140-170 m/s) was below the well-known value of soil (Nc=10) obtained by simple corn penetration tests. The S-wave velocity value and Nc were positive correlation in survey lines where the dispersion curves could be calculated. This study showed the efficiency of the surface wave method on slopes, and the distribution of the soil thickness can be more easily estimated than only using corn penetrometers.