The transition from weakening to strengthening in dehydrating gypsum: Evolution of excess pore pressures
The transition from weakening to strengthening in dehydrating gypsum: Evolution of excess pore pressures
复制标题
DOI：
10.1029/95gl00886
复制
发表时间：
1995-05
影响因子：
5.2
通讯作者：
Suz-chung Ko;D. Olgaard;U. Briegel
中科院分区：
文献类型：
--
作者：
Suz-chung Ko;D. Olgaard;U. Briegel
脱水反应会引起过高的孔隙流体压力，该压力足以影响岩石的机械强度和延展性。已经进行了实验室实验来研究脱水岩石中的这种现象，这些岩石的孔隙度最初可以忽略不计，但随着反应的进行而增加。多晶石膏样品首先在压力下加热以诱导脱水，然后在不同量的反应后轴向加载。在反应的前 1% 内，样品的极限强度下降并观察到脆化。最终强度在反应后3%内恢复并最终超过纯石膏。我们的结果表明，最初的弱化和脆化对应于样品内部的超孔隙压力脉冲。随后的强化是由孔隙压力的降低和产物相的较高强度引起的。
Dehydration reactions can induce excess pore-fluid pressures that are high enough to affect the mechanical strength and ductility of rocks. Laboratory experiments have been conducted to investigate this phenomenon in dehydrating rocks with porosities that are initially negligible but increase as the reaction progresses. Polycrystalline gypsum samples were first heated under pressure to induce dehydration, then axially loaded after different amounts of reaction. Within the first 1% of reaction, the ultimate strength of the sample decreased and embrittlement was observed. The ultimate strength recovered within 3% of reaction and eventually exceeded that of pure gypsum. Our results indicate that the initial weakening and embrittlement correspond to a pulse of excess pore pressure in the sample interior. Subsequent strengthening is caused by a decrease in pore pressure and the higher strength of the product phase.