干湿循环对岸坡粉砂岩劣化作用试验研究

Deteriorating Effect of Wetting and Drying Cycles on Bank Slope's Siltstone Properties

三峡库区30 m消落带的岩质岸坡是一个脆弱敏感地带,其岸坡岩体质量及其劣化规律日益成为人们研究的重点。选取三峡库区消落带巴东段某典型岸坡的紫红色粉砂岩为研究对象,通过现场钻探取芯、室内试样加工和"烘干-饱水"循环试验手段,对红层粉砂岩试样进行了单轴压缩和耐崩解试验研究。试验成果表明:研究区粉砂岩属于较坚硬岩,其单轴压缩强度随干湿循环次数增加而降低,经过20次干湿循环后,粉砂岩强度软化呈较软岩特征;粉砂岩具有高耐崩解性,耐崩解性指数Id与循环次数N呈对数关系,Id随N的增加而降低,Id下降速率随N的增加呈放缓趋势发展;相同循环次数条件下,高程越高的粉砂岩试样其Id越低。试验研究成果对三峡库区消落带岸坡岩体的劣化机理和岸坡稳定性分析等具有一定的参考价值。

As the hydro-fluctuation belt of 30 meters high in the Three Gorges Reservoir area becomes fragile and sensitive,the bank slope’s rock mass quality and its deterioration rules are increasingly becoming a research focus. In this paper,a typical siltstone rock slope in Badong segment of the Three Gorges Reservoir area was selected as a research object.Uniaxial compression test and slake durability test on siltstone samples were carried out by means of drilling in-site,in-door machining and wetting and drying cycles.The test results suggest that siltstones in the research area belong to hard rock,and its uniaxial compressive strength reduces along with the increase of cyclic number.However after 20 cycles of wetting and drying,the strength of siltstone weakens and displays the character-istics of soft rock.Moreover,the siltstone has high slake durability,and the slake durability index （Id ）is in log-arithm function relationship with the wet-dry cycle number （N）,which means that Id reduces with the increase of N,and the decrease of Id gradually slows down along with N increasing.Meanwhile,in the presence of the same cy-clic number,the higher elevation siltstone samples come from,the lower Id value they have.These research results could be reference for obtaining the deterioration rules of rock mass and rock slope stability analysis in the hydro-fluctuation belt of Three Gorges Reservoir area.