This paper investigates the effect of drying environment, i.e. temperature and relative humidity, on the engineering properties and microscopic pore size distribution of an expansive soil. The shrinkage tests under di...This paper investigates the effect of drying environment, i.e. temperature and relative humidity, on the engineering properties and microscopic pore size distribution of an expansive soil. The shrinkage tests under different drying temperatures and relative humidity are carried out in a constant climate chamber. Then, the undisturbed samples, prepared in different drying environment, are used for the triaxial tests and mercury intrusion tests. It is found that the drying environment has noticeable influence on the engineering properties of expansive soils and it can be characterized by the drying rate. The linear shrinkage and strength increase with the decrease of the drying rate. The non-uniform deformation tends to happen in the high drying rate, which subsequently furthers the development of cracks. In addition, during the drying process, the variation of pores mainly focuses on the inter-aggregate pores and inter-particle pores. The lower drying rate leads to larger variation of pore size distribution.展开更多
Laboratory tests were carried out in order to evaluate the efficacy of five inert dust （Puliangtai, G-1, G-2, G-3 and G-4） against the high level phosphine resistance Cryptolestesferrugineus （Stephens）. The relati...Laboratory tests were carried out in order to evaluate the efficacy of five inert dust （Puliangtai, G-1, G-2, G-3 and G-4） against the high level phosphine resistance Cryptolestesferrugineus （Stephens）. The relative phosphine resistance of two strains of Cryptolestesferrugineus （Stephens） was measured by the method of knockdown at 2 mg/L of phosphine. The insects were exposed to the five inert dust on filter paper inside petri dishes for 1 day at 30 ±1℃and 65 ±1% relative humidity. Then, the adults were held for 4 days with food at the same conditions without inert dust in surface bioassay. Also, they were placed in 25 ±1℃ and 65 ±1% relative humidity in grain bioassay. In surface bioassay, two strains （JXCF and YYCF） ofCryptolestesferrugineus （Stephens） were susceptible to the five inert dust at 0.08 g/m2 and 0.1 g/m2. G-3 appeared the most effective treatment against both strains, since its efficacy was 3-6 times higher than the other four inert dust tested. YYCF strain was more susceptible than JXCF, with 1-4 times higher mortality level. This research indicated that inert dusts were effective on phosphine-resistance Cryptolestesferrugineus （Stephens） populations.展开更多
基金financially supported by the National Natural Science Foundation of China (Grant No. 41430634)the State Key Laboratory of Geomechanics and Geotechnical Engineering (Grant No. Y11002)
文摘This paper investigates the effect of drying environment, i.e. temperature and relative humidity, on the engineering properties and microscopic pore size distribution of an expansive soil. The shrinkage tests under different drying temperatures and relative humidity are carried out in a constant climate chamber. Then, the undisturbed samples, prepared in different drying environment, are used for the triaxial tests and mercury intrusion tests. It is found that the drying environment has noticeable influence on the engineering properties of expansive soils and it can be characterized by the drying rate. The linear shrinkage and strength increase with the decrease of the drying rate. The non-uniform deformation tends to happen in the high drying rate, which subsequently furthers the development of cracks. In addition, during the drying process, the variation of pores mainly focuses on the inter-aggregate pores and inter-particle pores. The lower drying rate leads to larger variation of pore size distribution.
文摘Laboratory tests were carried out in order to evaluate the efficacy of five inert dust （Puliangtai, G-1, G-2, G-3 and G-4） against the high level phosphine resistance Cryptolestesferrugineus （Stephens）. The relative phosphine resistance of two strains of Cryptolestesferrugineus （Stephens） was measured by the method of knockdown at 2 mg/L of phosphine. The insects were exposed to the five inert dust on filter paper inside petri dishes for 1 day at 30 ±1℃and 65 ±1% relative humidity. Then, the adults were held for 4 days with food at the same conditions without inert dust in surface bioassay. Also, they were placed in 25 ±1℃ and 65 ±1% relative humidity in grain bioassay. In surface bioassay, two strains （JXCF and YYCF） ofCryptolestesferrugineus （Stephens） were susceptible to the five inert dust at 0.08 g/m2 and 0.1 g/m2. G-3 appeared the most effective treatment against both strains, since its efficacy was 3-6 times higher than the other four inert dust tested. YYCF strain was more susceptible than JXCF, with 1-4 times higher mortality level. This research indicated that inert dusts were effective on phosphine-resistance Cryptolestesferrugineus （Stephens） populations.
