长春地区粉质黏土融沉性质及影响因素试验研究

粉质黏土是一种对温度极其敏感的土,在季节性冻土区通常会产生较大的融沉变形,给道路、铁路等建构筑物造成严重破坏。长春地区土层以粉质黏土最为普遍,由于纬度、海拔、气候等原因,这里的粉质黏土融沉性与其它地区的有所不同,其影响因素的影响程度也有所不同。本文以长春地区粉质黏土为研究对象,通过对原状土样进行融沉压缩试验、冻胀试验和导热系数试验,分析了融沉系数与各因素之间的关系,提出了融沉系数经验公式,并采用灰色关联理论分析了各影响因素对融沉系数的影响程度。结果表明：①融沉系数随含水率、超塑含水率增大而增大,随干密度、烧失量增大而减小,其中可塑性影响最大；②融沉性与冻胀性呈显著正相关,冻胀率和冻胀压力越大,融沉系数越大；③粉质黏土融沉系数随深度的增大而增大,最大值出现在9～12m区间内；④长春地区粉质黏土的最优干密度为1.625g/cm_³；⑤根据灰色关联分析结果,长春地区粉质黏土各影响因素对融沉性的影响顺序由大到小依次为塑性指数、干密度、含水率、超塑含水率、导热系数、冻胀率和冻胀压力。在实际工程中可采取控制最优干密度或调整级配的方法来提高地基土或回填土的密实性,研究结果可为长春地区进行公路、铁路、地铁深基坑、建筑基础施工等提供科学依据与理论参考。

Experimental investigation on the properties of thawing settlement and influencing factors of silty clay in Changchun area

Silty clay is a kind of soil which is extremely sensitive to the temperature. In seasonal frozen soil area, it usually produces large settlement, which causes serious damage to road, railway and other buildings. Silty clay is the most common soil layer in Changchun area. Because of latitude, altitude, climate and other reasons, the thawing settlement of silty clay here is different from that in other areas, and the influence degree of its influencing factors is different. In this paper, silty clay in Changchun area is taken as the research object. Through the thawing settlement compression and frost heaving tests on undisturbed soil samples, the relationship between coefficient of thawing settlement and various factors is analyzed by regression analysis, and the sensitivity degree between thawing settlement coefficient and various factors is analyzed by grey correlation theory. The results show that: the thawing settlement coefficient increases with the increase of water content and water content over plasticity, and decreases with the increase of dry density and loss on ignition, among which plasticity has the greatest influence; the thawing settlement coefficient is positively correlated with frost heave, and the larger the frost heave rate and pressure is, the larger the thawing settlement coefficient is; the thawing settlement coefficient of silty clay increases with the increase of depth, and the maximum value appears in the range of 9-12M; the length is The optimum dry density of silty clay in spring area is 1.625g/cm³; according to the results of grey correlation analysis, the order of influence factors on the thawing settlement of silty clay in Changchun area is plastic index, dry density, water content, water content over plasticity, thermal conductivity, frost heaving rate and frost heaving pressure. In practical engineering, the method of controlling the optimal dry density or adjusting the gradation can be adopted to improve the compactness of foundation soil or backfill. The research results can provide scientific basis and theoretical reference for the construction of highway, railway, subway deep foundation pit and building foundation in Changchun area.