Structure analysis of weathered zone of bedrock slope by seismic prospecting

基岩边坡风化带地震勘探结构分析

• 批准号: 07454123
• 负责人: HIRANO Masashige
• 金额: $ 4.16万
• 依托单位: Osaka City University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07454123/
• 关键词: no-vegetation slope; seismic prospecting; surface velocity; mirage phenomenon; potential of sediment yield; 屈折法; 風化帯の構造; ミラージ現象

A particular landform is associated with a definite surface material produced under a balance of weathering to erosion, where a vegetation plays an important role. Destruction of the vegetation covering mountain slope often brings a serious envionmental problem concerning the run-off and sediment yield associated with the change of hydrological situation. From this point of view, the nature of surface materials exposing on bedrock slopes at the east of Himeji City and the Ashio Mountain have been investigated, based on the data by seismic prospecting. The refraction data showed that the slope with the inclination of 35 to 42 degrees have been underlain by the layr with the P-wave velocity of 800-1200 m/sec. The surface layr shows mirage phenomenon commonly on vegetation-covered and bedrock slopes, and this fact together with the critical velocity given above gives the estimation of the maximum loss of weathered material of ca. 10m thick at the ridge part covered with vegetation. The average depth of material loss for a wedge pinching from ridge to vally head is estimated ca. 5m, and this gives the potential of sediment yield by destruction of vegetation cover form slopes under humid climate.

一个特定的地形与一定的地表物质有关，这些物质是在风化与侵蚀的平衡下产生的，其中植被起着重要的作用。山坡植被的破坏往往会带来严重的环境问题，即与水文形势变化相关的径流和产沙问题。从这一观点出发，根据地震勘探资料，对姬路市东部和芦尾山基岩边坡上暴露的地表物质的性质进行了调查。折射资料表明，在35 ~ 42度的斜坡上，存在着纵波速度为800-1200米/秒的地层。在植被覆盖和基岩边坡上，表层普遍存在海市蜃楼现象，这一事实与上述临界流速一起，给出了约200 m风化物最大流失量的估计。山脊部分植被覆盖处厚10 m。本文估计了从山脊到谷头的楔尖缩的平均材料损失深度。5 m，这说明在湿润气候条件下，坡面植被破坏具有一定的产沙潜力。