|Alternative Title||Characteristics of Ancient Wreathering Crust of the Cretaceous Redbed Mudstone in Lanzhou Area
|Place of Conferral||兰州
|Other Abstract||Red bed and loess are widely distributed in western China.The ancient weathered red bedrock under the loess frequently form the bottom boundary of the loess landslide,and it is the control boundary condition.Therefore,knowing the weathering characteristics and engineering properties of weathered mudstone has important significance for the prevention and treatment of loess landslide in the study area.In this paper,we take cretaceous red weathered mudstone in Lanzhou city and the surrounding areas as research objects,processing weathering degree classification and zoning of red bed mudstone within the scope of 1 m under pebble bed,the interaction for collapsing of ancient weathered mudstone and water-rock interaction has been analyzed,the control function of the ancient weathered mudstone to loess landslides is discussed. Main conclusions are as follows:
(1)The results of hardness test,the springback test and susceptibility test showed the same rule.Namely its value in the surface is smaller,with the increase of depth the value is increases.
(2)Magnetic susceptibility test of the nine rock profiles showed that each profile has same tendency which is the magnetic susceptibility is larger on the surface and decreases with the increase of depth.The cause of the increased surface susceptibility is mainly weathering and pedogenesis.
(3)Disintegration test showed that rock disintegration is very strong at 0-30cm below pebble bed and the disintegration degree is close to 100%,rock disintegration is strong at 30-50cm and weaker at 50-100cm,also the weakest at 90-100cm,of which the disintegration degree is less than 50%.
(4)Experimental results show that the depth of strong weathered layer at the surface of cretaceous ancient weathered red mudstone is rather larger which ranges 30-50cm under pebble bed,relatively the depth of strong weathered layer of argillaceous sandstone profile is smaller which ranges 20-30cm under pebble bed.|
周建基. 兰州地区白垩系红层泥岩的古风化壳特征研究[D]. 兰州. 兰州大学,2015.
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