Estimation of the occurrence of a volcanic mud flow based on the theory of liquefaction of a volcanic ash layer caused by vibration of an earth quake or impact force of a slope failure

基于地震振动或边坡破坏冲击力引起的火山灰层液化理论估计火山泥流的发生

• 批准号: 01560171
• 负责人: 谷口 義信
• 金额: $ 1.6万
• 依托单位: Miyazaki University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1989
• 资助国家: 日本
• 起止时间: 1989 至 1991
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-01560171/
• 关键词: volcanic mud flow; volcanic ash; fluidization; vibration; dilatancy; shearing resistance force; 液状化

In this study, first it was tried to make clear the mechanism of the fluidization of volcanic ash layer by the vibration of an earth quake or impact force of a slope failure. This volcanic ash layer lain between volcanic accumulations is made by falling ash in an area of active volcano, next it was to predict the occurrence of a volcanic mud flow based on the theory of liquefaction of the mass of volcanic ash caused by the action of vibration or impact force stated above. As a result, the followings could be clarified.Judging from the result of the rheological test of a slurry consisted of volcanic ash and water, it can be defined as an entirely volcanic mud flow when the volumetric concentration of it is over 15%. When the vibration with low frequency acts on a slurry with the concentration of over 48.5% which consists of the only volcanic ash, the effect of dilatancy presents conspicuously itself, and the shearing resistance force of it increases in accordance with the number of vibr … More ation. When the concentration of it gets to about 66%, it presents entirely plasticity and the nobility of it decreases greatly. But the effect of dilatancy is prevented and the mobility of it increases when small gravels are mixed into that slurry, because the particle sizes in the slurry are not so homogenious as those in the slurry consisted of the only volcanic ash. The mobility of it gets the highest at the mixing ratio of about 40%. The mass of volcanic ash is easily fluidized in only few seconds by the vibration with low frequency of 5 cycle/sec and the amplitude of lcm- 2cm in the concentration below 66%.When a volcanic ash layer suffers from the vibration with high frequency like an earth quake, the critical angle for the occurrence of the movement of it decreases by 20ﾟ - 30ﾟ in comparison with that in the usual state when any vibration dose not act on it. The apparent internal friction angle of a slurry with high concentration falls much lower than that with low concentration. This means that liquefaction of volcanic ash layer would be easily caused by the vibration like an earth quake or impact force of a slope failure in an area of active volcano even if in a little rain fall. Less

在本研究中，首先试图弄清火山灰层在地震或滑坡冲击力作用下的流态化机理。这一位于火山堆积之间的火山灰层是由活火山区域内的落灰形成的，其次是根据上述振动或冲击力作用下火山灰质量块液化的理论来预测火山泥石流的发生。从火山灰和水组成的泥浆的流变性试验结果来判断，当其体积浓度大于15%时，可以定义为完全火山泥石流。当低频振动作用于浓度大于48.5%的仅含火山灰的泥浆时，其剪胀效应明显显现，其抗剪阻力随可控震源…个数的增加而增大。更多的时间。当它的浓度达到66%左右时，它呈现出完全的塑性，其高贵程度大大降低。但是，当小砾石混合到该泥浆中时，由于泥浆中的颗粒尺寸不像仅由火山灰组成的泥浆中的颗粒那样均匀，因此防止了膨胀效应，并增加了其流动性。当混合比在40%左右时，其迁移率最大。在频率为5周/秒的低频振动下，火山灰的质量在几秒钟内就很容易流态化，在浓度低于66%的情况下，振幅为1 cm-2 cm。当火山灰层受到地震等高频振动时，其运动发生的临界角比正常状态下不受任何振动作用时减小20ﾟ-30ﾟ。高浓度浆体的表观内摩擦角比低浓度浆体的表观内摩擦角要小得多。这意味着活火山地区的火山灰层即使在降雨较少的情况下，也很容易受到地震等振动或斜坡崩塌冲击力的影响而发生液化。较少

项目成果

Taniguhi,Y.Hirano,M.Hikida,M.: "Study on the Volcanic Mud Flow of Ichinomiya on 2 July in 1990,Japan-U.S.Workshop Abstracts" Snow Avalanche,Landslide,Debris flow Prediction and Control. 19-19 (1991)

Taniguhi,Y.Hirano,M.Hikida,M.：“1990年7月2日一宫火山泥流研究，日美研讨会摘要”雪崩、滑坡、泥石流预测与控制。

Taniguchi,Y.,Hirano,M.,Hikida,M.: "Study on the Volcanic Mud Flow of Ichinomiya on 2 July in 1990,JapanーU.S.Workshop Abstracts" Snow Avalanche,Landslide,Debris Flow Prediction and Control. 19-19 (1991)

Taniguchi, Y., Hirano, M., Hikida, M.：“1990年7月2日一宫火山泥流研究，日美研讨会摘要”雪崩、滑坡、泥石流预测与控制19-19。 (1991)

Taniguchi, Y: "Hirano, M. and Hikida, M. : Study on the Volcanic Mud Flow of Ichinomiya on 2 July in 1990" Snow Avalanche, Landslide, Debris Flow Prediction and Control, Japan- U. S. Workshop Abstracts.

Taniguchi, Y：“平野 M. 和 Hikida, M.：1990 年 7 月 2 日一宫火山泥流研究”雪崩、滑坡、泥石流预测与控制，日美研讨会摘要。

谷口 義信: "桜島火山泥流の流れの特性" 砂防学会ワ-クショップ. 21-29 (1990)

谷口义信：“樱岛火山泥流的流动特征”萨博学会研讨会21-29（1990）。

谷口 義信: "桜島火山泥流の流れの特性" 砂防学会ワ-クショップ荒廃渓流における地形変化と堆積土砂の制御. 21-29 (1990)

谷口义信：《樱岛火山泥流的流动特征》侵蚀控制学会研讨会地形变化与退化山溪中的沉积物沉积控制21-29（1990）。