滇池湖相泥炭土固结系数及次固结系数研究

Study on the coefficient of consolidation and secondary consolidation of lacustrine peat soil around the Dian Lake

泥炭土通常被判定为高压缩性土,其主、次固结作用对该类地基上的建筑物沉降有着重要的影响。针对昆明滇池地区湖相泥炭土,通过一系列高压固结试验,开展了泥炭土主、次固结系数的研究。结果表明:滇池湖相泥炭土的固结系数C_v随着固结压力p的增加呈现逐渐减小的趋势,C_v与lgp具有幂函数关系,且随着压力的增加C_v-lgp曲线可分为快速减小、缓慢减小和趋于稳定3个阶段。次固结系数C_a随着固结压力的增大呈现先增大后减小、再次增大而后再次减小最后逐渐衰减稳定的规律,C_a与压力对数lgp符合三阶高斯函数关系。根据试验和分析结果,对滇池湖相泥炭土的固结机理进行了探讨,认为土体结构的破坏、重组、压实再造及结合水膜、矿物质变化、重结晶作用等过程导致了土体呈现出复杂而又规律变化的固结特性。

Peat soil is generally deemed as high compressible soil.The consolidation and secondary consolidation influences greatly on the building settlement.According to a series of high pressure consolidation tests of lacustrine peat soil in the Dian Lake area,the coefficients of consolidation and secondary consolidation are analyzed and studied.The results show that the coefficient of consolidation C_v declines gradually with the consolidation pressure p increases,and the C_v-lgp curve conforms to power function relationship,which can be divided into three stages,i.e.rapid decline,slow decline and stable stage.The secondary consolidation coefficient C_a increases and then decreases,then increases again and then decreases again,and then gradually decays and stabilizes with the increase of consolidation pressure,and the C_a-lgp curve conforms to third order Gaussian function relationship.Based on the test and analysis result,consolidation mechanism of lacustrine peat soil in the Dian Lake area is discussed.The damage,recombination,compaction and reconstruction of soil structure as well as the changes of bound water film,minerals and recrystallization will result in the complicated and regular consolidation of the soil.