有机质是土中常见组分，对土体热性质有显著影响。为明确有机质对黏性土热传导系数影响与机制，以膨润土为基质，通过添加腐殖质制备不同有机质含量土样。利用热探针法测定其热传导系数λ ，分析l随干密度ρd、含水率w（饱和度Sr）和有机质含量wu的变化规律；并通过分析膨润土对有机质的吸附特征，探讨了有机质对土热传导系数影响机制。试验结果表明：有机质含量wu相同时，热传导系数λ 随干密度ρd、含水率w、饱和度Sr增大而增大。在土体饱和、ρd相同条件下，λ随wu增大而减小，但并非单调线性递减关系；可分为急剧下降段、过渡段和平缓下降段3个阶段。过渡段对应的wu大致范围为7.5%～15.0%。通过傅积平法测试得出膨润土对紧结态有机质饱和吸附量wu

1大致为8.0%，对紧结态+稳结态有机质的饱和吸附量wu

2约为14.0%；即有机质赋存形态变化的两个阈值（wu

1、wu

2）和λ-wu关系曲线过渡段对应的wu基本吻合。机制分析表明：除有机质含量外，土中有机质赋存形态变化也是影响土热导系数的重要因素。分析了几种热导系数理论预测模型对含有机质黏性土的适用性。Organic matter is a commoncomponent in soil and has a significant effect on the thermal properties ofsoil. To clarify the influence and mechanism of organic matter on the thermalconductivity of clay

bentonite was used as the matrix to prepare soil sampleswith different organic matter contents by adding humus. Thermal conductivitycoefficient λ was measured by thermal probe

and the variationof λ with dry density ρd

water content w (degree of saturation Sr) and organic matter content wu were examined. By analysing the adsorptioncharacteristics of bentonite to organic matter

the influence mechanism oforganic matter on soil thermal conductivity was discussed. The results showthat the thermal conductivity coefficient λ increases with the increase of dry density ρd water content w and degree of saturation Sr when wu is the same. When the dry density ρd of saturated soil is the same

l decreases with the increasing of wu

but is not a monotonelinear decline. It can be divided into three stages: sharp descent stage

transition stage

and gentle descent stage. The approximate range of wu corresponding to the transition stage is 7.5%to 15.0%. The saturated adsorption capacity wu

1 of bentonite to compactorganic matter is about 8%

and that of wu

2 to compact + stable organicmatter is about 14.0%. In other words

the two thresholds (wu

1

wu

2) of the variation oforganic matter occurrence form are consistent with the wu corresponding to thetransition section of the λ-wu relation curve. Mechanism analysis shows thatin addition to the content of organic matter

the change of organic matteroccurrence form is also an important factor affecting the thermal conductivityof the soil. The applicability of several theoretical prediction models ofthermal conductivity for clay soil containing organic matter was analysed.