Deformation measurement and analysis play an important role in geotechnical model tests. Using the concept of quadrilateral isoperimetric element, the strain filed was achieved from the calculation method based on displacement modes, and the verification results show that this measurement technique has a reliable precision. The soil deformation in model test of square shallow foundation was measured by using this technique, and the results show that the measurement system based on digital image correlation method can realize the whole process quantitative measurement of soil displacement field and shear strain filed. This deformation measurement technique provides a tool for the qualitative and quantitative analysis of soil micromechanics characteristics. 相似文献
In this paper the finite element analysis was carried out for a composite vertical axis wind turbine with lift-drag combined starting structures to ensure the structure safety of a vertical axis wind turbine(VAWT). The static and modal analysis of rotor of a composite vertical axis wind turbine was conducted by using ANSYS software. The relevant contour sketch of stress and deformation was obtained. The analysis was made for static structural mechanics, modal analysis of rotor and the total deformation and vibration profile to evaluate the influence on the working capability of the rotor. The analysis results showed that the various structure parameters lie in the safety range of structural mechanics as given in the relative standards. The analysis showed the design safe to operate the rotor of a vertical axis wind turbine. The methods used in this study can be used as a good reference for the structural mechanics′ analysis of VAWTs. 相似文献
In recent years, agricultural land in Switzerland has been increasingly used as temporary access ways for heavy machinery in road and pipeline construction operations. The Swiss soil protection law requires that measures are taken to prevent soil compaction in such operations, but gives no criteria to determine tolerable loads. We studied the compaction sensitivity of a loess soil (Haplic Luvisol) at different soil moisture conditions in a field traffic experiment and by a numerical model on the computer using finite element analysis. Two plots, one wetted by sprinkling and one left dry (no sprinkling), were traversed by heavy caterpillar vehicles during construction of a large overland gas pipeline. Compaction effects were determined by comparing precompression stresses of samples taken from trafficked and non-trafficked soil. A finite element model with a constitutive relation, based on the concept of critical state soil mechanics, was used to interpret the outcome of the field trials.
We found significantly higher precompression stresses in the trafficked (median 97 kPa) compared with the non-trafficked (median 41 kPa) topsoil of the wet plot. No effect was evident in the topsoil of the dry plot as well as in the subsoils of the wet and the dry plot. The observed compaction effects were in agreement with the model predictions if the soil was assumed to be partially drained, but disagreed for the wet subsoil if fully drained conditions were assumed. Agreement between model and experimental results also required that the moisture dependence of the precompression stress was taken into account. 相似文献
Heavy sugarbeet harvesters may compact subsoil. But it is very difficult to study this by field experiments that resemble agricultural practice. Therefore, an analysis was made by a finite element method (FEM) for a relevant calcaric fluvial soil profile, the mechanical properties of which were largely known. Measuring data of this Lobith loam soil includes preconsolidation stress, compression index and swelling index, all as a function of depth. Using these three types of soil parameters calculations have been done for tyre sizes, inflation pressures and wheel loads that occur with heaviest sugarbeet harvesters available on the European market in 1999. Because no values on soil cohesion were available, the calculations were done for several cohesion levels. The results include the detection of regions with Mohr–Coulomb plasticity and regions with cap plasticity (compaction hardening). For the soil studied—a typical soil strength profile for arable land with ploughpan in the Netherlands in the autumn of 1977—all studied combinations of wheel load and inflation pressure did not induce compaction in and below the ploughpan. The size of the region with Mohr–Coulomb plasticity decreased with increasing cohesion. It appeared from a sensitivity analysis that, although soil modelling may use a great number of soil parameters, the most important parameters seem to be: preconsolidation stress and cohesion. There is an urgent need for data of these parameters that are measured on a great range of subsoils and subsoil conditions. 相似文献
针对生物软措施的力学固土护坡作用进行了力学机制方面的探讨,提出植物根系网固土力学机制模式的四个层次,以及对不同草本植物根系的固土性能进行了力学试验比较。结果表明不同植物根系具有不同的抗拉强度。香根草根系平均抗拉强度最大达85 m Pa,其次为假俭草,平均抗拉强度27.3 m Pa,白三叶根系平均抗拉强度为24.6 m Pa,莎草根系平均抗拉强度为24.5 m Pa,宜安草根系平均抗拉强度为19.7 m Pa,百喜草根系平均抗拉强度为19.23 m Pa,马尼拉草根系平均抗拉强度为17.5 m Pa,狗牙根根系平均抗拉强度为13.45 m Pa。不同的植物根系具有不同的抗拉强度、不同的固土性能与其遗传结构及其组织材料不同有关。充分了解和认识植物根系固土性能,科学合理运用生物软措施代替或部分代替工程措施在我国繁重的生态环境保护和恢复的基本建设工程项目中具有重要的应用价值和意义。 相似文献