Сопоставление результатов испытаний мёрзлых грунтов на одноосное сжатие при ступенчатой и постоянной нагрузках
| Jazyk: | ruština |
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| Rok vydání: | 2016 |
| Předmět: | |
| Zdroj: | Электронное научное издание Альманах Пространство и Время. |
| ISSN: | 2227-9490 |
| Popis: | Целью настоящей работы является сопоставление результатов испытаний образцов мёрзлых грунтов на одноосное сжатие. В работе анализируются и сопоставляются результаты одноосных испытаний мёрзлых грунтов различными методами с привлечением формул расчёта длительной прочности и её снижения с возрастанием времени. Обработка результатов испытаний позволила получить коэффициенты перехода от кратковременной к длительной прочности мёрзлых грунтов ( Kt QUOTE ). Для мелких песков величина коэффициента Kt составляет около 0,8; для слабо засолённых супесей коэффициент Kt принимает значение 0,54; для влажных не засолённых суглинков Kt = 0,69; для суглинков среднеи сильнозасолённых от 0,29 до 0,60; для сильнольдистых глинистых грунтов Kt = 0,39. Для нельдистых плотных средне засолённых глинистых грунтов коэффициент Kt QUOTE = 0,42. One of the methods for determining the strength of frozen soils is the testing of samples on uniaxial compression. When a series of similar samples of frozen soil is subjected to compression at different, but constant for each sample voltages exceeding the long-term strength, the process inevitably results in the emergence of a progressive course and subsequent brittle or viscous destruction of the sample. The aim of our work is to compare the results of tests on samples of frozen soils on uniaxial compression. We examine and compare results of uniaxial tests frozen soils of different methods involving calculation formulas of long-term strength and decrease with the increase of time. We carried out tests in freezing chambers, maintaining temperature with high accuracy of ±0.25°С at a temperature of minus 4°С. We determined physical properties of the soils for the 99 monoliths that are soil samples. In laboratory conditions, we carried out determination of dry density of soil density of soil particles, organic matter content, values of the salinity and chemical composition of water-soluble salts. Monoliths of frozen soils from Yamal Peninsula were collected in the depth interval of 1.0-30.0 m, which is predominantly shallow and silty sands, light and heavy loam (with a predominance of light loam and sandy loam, which met throughout the section of the survey sites. By granulometric composition, sands are small and homogeneous; among silty sands the heterogeneous varieties are dominated. In general, ice-rich varieties are dominated in the sands, and not-icy and slightly icy are dominated in the clay soils. We investigated characteristic feature of frozen soils in the presence of saline samples varied between weakly and strongly saline. Salinity of the sands does not exceed 0.49%, and it dominated in the values of 0.05-0.15%; sandy clay has maximum salinity of 0.29%, the principal value range 0.20-0.29%; salinity of the light loam reaches values of 1.5%, salinity of the loamy clay reaches values of 1.8%, the prevailing values of salinity of the loams are 0.20-0.70%. Organic matter in soils is present, usually in the upper layer of soil massif in the form of an admixture of peat in the amount to 31.3%, also in the context of the present interlayers and lenses of peat. Processing of results enabled to obtain the coefficients of the transition from short-term to long-term strength of frozen soils (Kt). For fine sands, value factor Kt is about 0.8; for weakly saline, loam factor Kt takes the value of 0.54; for non-wet saline, loam Kt = 0.69; for loam medium and strongly saline, this characteristic vary from 0.29 to 0.60; for selenologist clay soils, Kt = 0.39. For non-icy dense medium saline clay soils, factor Kt = 0.42. We obtained all the results for the most common frozen soils from Yamal Peninsula at minus 4 oC. Further research in this direction will allow calculating the transfer factors for other temperatures. Our experiments have shown it is necessary to take into account the forces of the soil freezing with the lateral surface of the pile, set in the frozen thicker, since the strength of freezing on the side of the pile up to 80% of the bearing capacity of the pile. Replacement of the bearing capacity of piles (consisting of ground resistance under the end of the piles and freezing on its side surface) on the parameters of test samples for uniaxial compression is also invalid, because the schema of the soil under the action of a normal load (uniaxial compression) and shear (freezing) different. |
| Databáze: | OpenAIRE |
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