【文章內(nèi)容簡介】 ure Cp. The mean, for the three levels, increase in pressure, with dropping temperature, was kPa ℃1 in the first cycle, kPa ℃1 in the second, and kPa ℃1 in the third, while with increasing temperature the corresponding values were , and kPa ℃1, respectively. The authors concluded that the relationship between the lateral thermal pressure and the temperature change was linear, and that the pressures during temperature increase were , and % higher than in the case of the dropping temperature in the first, second and third cycles, respectively. Another model of granular material in storage, which took into account loads induced by silo walls, as well as the silo wallgrain and silo bottomgrain interfaces, was presented by Zhang et al. [25]. That model did not reflect changes in temperature. Therefore, Li et al. [16] expanded a new version of the model based on finite element analysis by including values characteristic for the material stored within the range of average temperatures. The model was tested on wheat grain with an initial moisture content of 10% and a bulk density of 825 kg m3. The silo with the wheat grain was subjected to cyclic temperature changes between 32 and 22176。C with an amplitude of 10176。C per h. After the application of an additional loading of 40 kPa, the grain was let rest for 2 h. They tested additional grain loading at various depths, which permitted the determination of the silo wall deformation [23]. The twohour period of rest allowed the grain to attain a stable state of stressmeasuring instruments did not record any changes of strain in time. Tests performed on the empty silo showed that no deformation occurred in the upper and the lower parts of the silo [15].Zhang et al. [24] studied the changes in the value of pressure quotient k in relation to the distance from the silo axis and the grain layer depth under the effect of static and thermal loads in shallow and deep silos. They analyzed stress in cylindrical grain silos using the model of second generation. They applied the analysis to two grain silos: one with a diameter of 3 and 9 m high, and another of 9min diameter and 9 m high. Both were made of corrugated sheetmetal and filled with wheat grain with 10% moisture content and an initial bulk density of 801 kg m3. 。In both cases they determined the main direction of stress within the grain mass and the ratio k of lateral to vertical pressure. They found that neither the lateral nor the vertical static pressures were uniform, but decreased in the direction from silo axis towards the walls. Lateral thermal pressures increased with the increasing distance from the silo axis, while the vertical thermal pressures decreased. The lateral pressure increased more than the vertical when the grain temperature dropped to 30176。C. The lateral pressure increase close to the silo wall was much stronger than that at the silo axis when the temperature dropped to 30176。C. Changes in the k ratio value were slight, irrespective of the distance from the silo axis in the case of static loads, but increased to 2063% with the thermal loads. Changes in the k ratio value were slight when referenced to the grain layer depth in static loading, but decreased (by an average 20%) from the top to the bottom of the silo in thermal loading. The average thermal values of k were higher than the static.Silos are usually filled with grain of a varied moisture content. Grochowicz et al. [5] and [6,7] studied the effect of the grain layer moisture content on the distribution of temperature and water, and on the pressures exerted by the grain on the silo walls. They showed that interlayer differences in the grain moisture content cause strong increases of grain temperature and pressures exerted on the silo walls at the interlayer boundaries. The problems presented above indicate the strong need for studies on grain temperature and moisture content, and on the effect of those factors on pressures acting on structural elements of silos. Changes in pressures can be caused not only by changing external temperature. They are also strongly affected by the initial moisture content of the grain, as this affects the process of microorganisms and insect evolution, causing increased temperature and moisture content. SCOPE AND METHODThe study presents the results of model investigations involving measurements of pressure acting on silo walls and grain temperature. The material used was triticale grain with initial moisture content levels of 13, 16 and 18% ., stored at a constant external temperature of 15176。C for a period of 25 days. A moisture content of 13, 16 or 18% . was achieved by the addition of adequate water volume and was calculated by the equation: Mw=Mg (w2w1)/(100w2) (3)where: Mw volume of required water addition to achieve the moisture content of w2, kg。 Mg mass of watered grain, kg。 w1initial grain moisture content, % .。 w2required grain moisture content, % . Watered grain was stored in a tightly closed barrel for 72 h. It was rotated every few hours to equalize the moisture content. Before starting the test, the moisture content was controlled. A schematic diagram of the test stand is presented in Fig. 1. The main element was the silo (1) which was provided with a water jacket. The external diameter o