CAJ | 학술논문

近年来重大地下工程中揭露一套结构疏松，自稳能力差，涌水、塌方等工程事故频发的岩层，即疏松砂岩。分析其成因及赋存环境对认识其特殊性质及应对相关工程问题都具有重要意义。本文结合甘肃新近系沉积环境，采用室内粒度分析试验、SEM及XRD试验，并与现代沙漠风成沙与河床水成沙对比，从其分布及产出特征、粒度特征、石英颗粒表面特征及胶结特征等方面对其成因进行分析。研究表明，这套疏松砂岩与相邻岩层产出相近，归属于甘肃新近系红层；其粒径相对集中，胶结物含量少、胶结差，孔隙度大；石英颗粒表面发育蝶形坑、麻面及硅质沉淀等典型特征。综合其各种特征，甘肃新近系疏松砂岩为新近纪干热气候环境下风沙活动的产物，且受后期赋存水环境作用的影响。
근년래중대지하공정중게로일투결구소송，자은능력차，용수、탑방등공정사고빈발적암층，즉소송사암。분석기성인급부존배경대인식기특수성질급응대상관공정문제도구유중요의의。본문결합감숙신근계침적배경，채용실내립도분석시험、SEM급XRD시험，병여현대사막풍성사여하상수성사대비，종기분포급산출특정、립도특정、석영과립표면특정급효결특정등방면대기성인진행분석。연구표명，저투소송사암여상린암층산출상근，귀속우감숙신근계홍층；기립경상대집중，효결물함량소、효결차，공극도대；석영과립표면발육접형갱、마면급규질침정등전형특정。종합기각충특정，감숙신근계소송사암위신근기간열기후배경하풍사활동적산물，차수후기부존수배경작용적영향。
In recent years,a set of strata with loose structure and worse self-stabilization,which named unconsolidated sandstone,has been exposed by several large underground engineerings with frequent engineering accidents,such as gushing water,collapse and other problems.Analyzing its origin and occurrence environment is of great significance both in understanding the essence of its special properties and dealing with the relevant engineering issues. Combined with sedimentary environment of the Neogene in Gansu, the origin of the unconsolidated sandstone,which can be comparing with modern desert aeolian sand and beach sand,is studied by using grain size analysis,scanning electronic microscope (SEM) and X-ray diffraction (XRD ) by which its distribution characteristics,occurrence and exposure characteristics,grain-size characteristics,quartz sand grain surface characteristics and cementation characteristics,would be discussed in this paper.The analysis result shows that the unconsolidated sandstone,which belongs to the parts of the Neogene red layers in Gansu province,has the same occurrence and exposure characteristics as adjacent strata.And this sandstone has well-sorted,large porosity and less clay minerals.Its quartz grain surface shows some butterfly shaped craters,surface pockmarks and siliceous sediments.All of those characteristics can be inferred that the unconsolidated sandstone in Gansu is the wind-sand activity product with dry and hot climate in late Neogene,and parts of the strata are influenced by water environment afterwards.