吸水率和吸水时间对红砂岩施密特硬度的影响

Influence of water absorption rate and time on the Schmidt hardness of red sandstone

将红砂岩试样在清水中浸泡,测量不同时间点红砂岩的吸水量,运用L型施密特锤测试干燥和各时间点红砂岩表面的施密特硬度,最终测试各试样在崩解初或饱水状态下的抗压强度.分析红砂岩的吸水速率、吸水率随吸水时间的变化趋势,红砂岩表面施密特硬度与吸水时间和吸水率的关系,施密特硬度与抗压强度之间的关系,结果表明:红砂岩在第1h内的吸水量较大,吸水速率随吸水时间延长而下降;红砂岩的施密特硬度随吸水时间和吸水率的增加而降低,当达到饱和吸水率后,随浸水时间延长,施密特硬度继续降低;通过施密特硬度估计的红砂岩抗压强度值比实测值稍微偏大,但能够判断出红砂岩抗压强度的大致范围;施密特硬度与抗压强度之间的关系可以用数学公式表示.

Red sandstones were soaked in clean water, and absorption water content was tested at different soaking time. The Schmidt hardness of red sandstones at dry status and different soaking time was measured using Schmidt hammer, and each sample＇s uniaxial compressive strength, when it began to disaggregate or got water-saturated, was also measured. The varia- tion of water absorption with increase of soaking time for red sandstone, the relation between Schmidt hardness and soaking time, that between Schmidt hardness and water content, and that between Schmidt hardness and uniaxial compressive strength were investigated. The re- sults show that the water absorption of red sandstones is maximized in the first hour of soaking time, and declined with the growth of soaking time. Schmidt hardness descends with the growth of soaking time and water content, even the samples are saturated, Schmidt hardness continues to descend, and the estimated uniaxial compressive strength obtained according to Schmidt hardness is a little higher than the tested one. The Schmidt hardness can be used to estimate approximate scope of red sandstone＇s uniaxial compressive strength. The relation be- tween Schmidt hardness and compressive strength of red sandstone can be expressed using mathematic formula.