钙质粉土的固结特性试验研究  

Experimental study of consolidation properties of calcareous silt

作　　者：雷学文[1] 丁豪 王新志[2] 沈建华[2] 孟庆山[2] LEI Xue-wen;DING Hao;WANG Xin-zhi;SHEN Jian-hua;MENG Qing-shan(School of Urban Constriction,Wuhan University of Science and Technology,Wuhan,Hubei 430065,China;State Key Laboratory of Geotechnical Mechanics and Engineering,Wuhan Institute of Geotechnical Mechanics,Chinese Academy of Sciences,Wuhan,Hubei 430071,China)

机构地区：[1]武汉科技大学城市建设学院,湖北武汉430065 [2]中国科学院武汉岩土力学研究所岩土力学与工程国家重点实验室,湖北武汉430071

出　　处：《岩土力学》2021年第4期909-920,共12页Rock and Soil Mechanics

基　　金：中国科学院战略性先导科技专项(A类)资助(No.XDA13010203);自然科学基金面上项目(No.41572297,No.41772336,No.41877267)。

摘　　要：由于水力吹填的分选作用,南海吹填珊瑚礁地基中含有厚度不均的细颗粒钙质粉土夹层。相比粗颗粒礁砂而言,钙质粉土的压缩性高、承载力低、沉降变形大,对建筑物安全造成不利影响。通过室内固结试验,查明了钙质粉土的压缩特性,揭示了钙质粉土的主固结沉降量、次固结沉降量、固结时间和固结速率特征,为更好地了解钙质粉土的工程性质和珊瑚礁地基沉降计算提供科学依据。试验结果表明:钙质粉土压缩系数在0.03~0.37 MPa-1之间,压缩模量在6.67~54.79 MPa之间;压缩系数与含水率成正比,与干密度成反比。其中,含水率小于15%的中密和密实钙质粉土的压缩系数小于0.1MPa^(-1),压缩模量大于20.0 MPa,属于低压缩性土;松散的钙质粉土均属于中压缩性土。与相同干密度和含水率的石英砂相比,石英砂的压缩系数比钙质粉土大,即钙质粉土比石英砂压缩性更低;与相同干密度和含水率的杭州湾粉土相比,两者均属于中压缩性土,但钙质粉土的压缩模量比杭州湾粉土略大,压缩系数略小;当荷载大于200 k Pa时,钙质粉土在固结试验前5 h固结度达到了0.95,因此,建议钙质粉土的固结试验在荷载小于200 kPa时固结时间仍取24 h,当荷载大于200 kPa时取5 h,此举将大大节省测试时间,提高测试效率。Due to the effect of sorting by hydraulic dredger fill,the foundation of dredged coral reef in the South China Sea contains fine calcareous silt interlayer with uneven thickness.Compared with coarse-grained calcareous sand,calcareous silt presents higher compressibility,lower bearing capacity and larger settlement deformation,which adversely affect the safety of buildings on coral reefs.In this paper,the characteristics of primary and secondary consolidation settlement,consolidation time and consolidation rate of calcareous silt were obtained through laboratory consolidation tests,for better understanding the engineering properties of calcareous silt and calculation of coral reef foundation settlement.The calcareous silt shows 0.03-0.37 MPa-1 of the compression coefficient and 6.67-54.79 MPa of the compression modulus.Compression coefficient is directly proportional to moisture content and inversely proportional to dry density.Compression coefficient lower than 0.1 MPa^(-1)and compression modulus more than 20.0 MPa occurs in moderately dense and dense calcareous silt with water content of less than 15%as low compressibility soil,but loose calcareous silt is moderately compressible.Compared with quartz sand under the same dry densities and moisture contents,the compression coefficient of quartz sand is higher than that of calcareous silt,while the compression modulus is lower than that of calcareous silt.Under the same dry density and water content,both Hangzhou Bay silt and calcareous silt show moderate compressibility.However,the compressive modulus of calcareous silt is slightly larger than that of Hangzhou Bay silt,and its compressive coefficient is slightly smaller.When the load exceeds 200 kPa,the degree of consolidation of calcareous silt reaches 0.95 in the first 5 hours of the consolidation test.Therefore,it suggests 24 hours for the consolidation time of calcareous silt under loading less than 200 kPa but 5 hours under loading greater than 200 kPa for the testing efficiency.

关 键 词：钙质粉土 干密度 含水率 压缩性指标 固结速率 

分 类 号：TU411[建筑科学—岩土工程]