干湿循环作用下红砂岩崩解的影响因素研究

RESEARCH ON INFLUENCING FACTORS OF RED SANDSTONE DISINTEGRATION DURING DRYING-WETTING CYCLES

红砂岩广泛分布于我国南方地区,因强度低、胶结程度差,且含有一定的膨胀性黏土矿物,此类岩石受水影响易发生崩解,从而易诱发多种地质灾害。选取湖南株洲地区的微膨胀红砂岩进行静态与扰动崩解试验,采用耐崩解性指数、标准基础熵、崩解比和分形维数等作为评价红砂岩崩解特性指标,探讨了烘干温度、试块质量、外界扰动和干湿循环作用等因素对红砂岩崩解特性的影响。研究结果表明,静态崩解方式下,相比于105℃和30℃,60℃的烘干温度更利于岩样崩解。而扰动崩解下,烘干温度对红砂岩崩解的影响几乎可以忽略不计。在烘干温度、试块质量等因素不变的情况下,外界扰动对红砂岩崩解特性存在显著影响。试块质量对红砂岩崩解特性存在一定的影响,试块质量越大,红砂岩崩解速率越快。干湿循环作用对红砂岩崩解的影响十分显著,随着循环次数增加,红砂岩的崩解破碎程度逐渐加大。

Red sandstone is widely distributed in southern China.Due to the low strength,poor cementation and swelling clay minerals,red sandstone is prone to disintegrate under the influence of water,which can easily induce a variety of geological disasters.The static and disturbed disintegration tests are conducted on the slightly swelling red sandstone collected form Zhuzhou area of Hunan Province.The effects of dry temperature,external disturbance,test block mass and drying-wetting cycle on the disintegration characteristic are explored using evaluating indexes,including slake durability index,standard basis entropy,disintegration ratio and fractal dimension.The results show that,under the static disintegration mode,the drying temperature of 60℃is more favorable to disintegrate for red sandstone than those of 105℃and 30℃.However,under the disturbed disintegration mode,the effect of drying temperature on the disintegration of red sandstone is almost negligible.Furthermore,in the case of constant temperature and test block mass,the external disturbance has a significant effect on the disintegration properties of red sandstone.Then,the test block mass has the influence on the disintegration behaviors of red sandstone.The faster disintegration rate occurs with the larger test block mass.In addition,the influence of drying-wetting cycle on the disintegration of red sandstone is very significant.The disintegration breakage of red sandstone gradually increases with the increasing cycle numbers.