報告書番号

U99075

タイトル（和文）

温度と有効拘束圧が珪藻土の透水性におよぼす影響

タイトル（英文）

The effects of temperature and confining pressure on the permeability of diatomite

概要 （図表や脚注は「報告書全文」に掲載しております）

大深度での堆積岩の化学，力学，物理的性質の変化を明らかにするために，珪藻土を用いて高温透水試験を実施した．試験温度は室温から140℃の間で有効拘束圧は0.5MPaから9.5MPaまでの間で変化させた．その結果，珪藻土の透水係数は温度の増加とともに大きくなり，一方，固有浸透係数は室温から140℃まで昇温させる過程において80℃～100℃の間で小さくなることが明らかになった．さらに，有効拘束圧の載荷・除荷により固有浸透係数はヒステリシスを示すこと，3.5MPa～4.5MPaの間で，著しく圧縮し珪藻遺骸が押しつぶされ，固有浸透係数が減少することが明らかになった．化学反応によるシリカの溶出体積は0.06％（80℃），0.12％(140℃)で透水性に影響を与えなかった．

概要 （英文）

The purpose of this experiment is to investigate the physical, mechanical, and chemical behavior of sedimentary rocks under the deep ground. We performed the permeability test of diatomite between room temperature and 140℃, under the effective confining pressure between 0.5MPa and 9.5MPa. The coefficient of permeability of diatomite increased with increasing temperature, but the intrinsic permeability was small between 80℃ and 100℃ (below140℃). The intrinsic permeability of diatomite decreased with increasing the effective confining pressure from 0.5MPa to 9.5MPa. Furthermore, that of diatomite showed hysteretic behavior for the loading ‐ unloading cycle of the effective confining pressure.The effective porosity remarkably decreased with increasing the effective confining pressure from 3.5MPa to 4.5MPa by compression of diatom frustle, however the intrinsic permeability did not remarkably decrease on this pressure. The amount of volume reduction by silica dissolution from diatom frustle was 0.06% at 80℃，0.12% at 140℃.

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