Frame anchor supporting structure is widely accepted in the loess area, especially in the multistage slopes along the road. However, the development between theory and practice is not synchronous, and there exist experience and uncertainty in the design process to a great extent. In response to this problem, the multistage loess slope supported by frame structure with anchors is taken as the research object, and the model test is carried out with the help of the large-scale geotechnical centrifuge under the condition of using prototype materials as much as possible. Then, according to the test data and phenomena, the structural stress and slope deformation concerned in the project are analyzed. The main differences in stress and deformation between the multistage loess slope supported by frame structure with anchors and other types of slopes are pointed out, and some targeted suggestions are given. The research results show that the frame anchor supporting structure and soil can always maintain coordinated deformation during centrifugal loading, and the failure process has certain toughness characteristics. The stress characteristics of the anchor rod and the sliding deformation range of the slope in the multistage loess slope supported by frame structure with anchors are different from the slope with structural surface and single-stage slope. The length of the anchoring section cannot be completely determined based on the potential sliding surface in the design. It is reasonable to strictly control the end position of the anchoring section from the perspective of changing the position of the potential sliding surface. The results obtained can enrich and improve the stability theory of multistage loess slope and provide guidance for engineering practice.

Like buildings with other types of foundations, buildings with pile foundations can tilt because of irrational designs, imperfections of foundation treatment, poor construction qualities, even the change of water environment during usage, etc. By studying and analyzing the causes for the inclination, this paper has proposed a theory of rectification and reinforcement for buildings with pile foundations based on the principle of counterforce center, which makes building be rectified by changing the counterforce center of pile foundation so that it can be in the same vertical line with the gravity center of upper structure. Then the calculation method was given. Combining with an engineering project, it has been proved that the principle of counterforce center is a good guidance for the rectification and reinforcement for buildings with pile foundations.

In this paper, an experimental approach is employed to investigate the reinforcing impact of geogrids on the dry-shrinkage cracking of loess. At various evaporation temperatures and for varying specimen thicknesses, the evolution of the surface fissures induced in the loess samples with and without geogrids was monitored and analyzed. According to the findings, the evaporation rate of the samples increased when the evaporation temperature was increased, and the thickness of the samples was reduced under the same conditions. At higher temperatures, geogrids had a substantial impact on reducing the evaporation rate and suppressing the dry-shrinkage cracks. The occurrence and development of the dry-shrinkage cracks of loess are divided into three stages: the formation stage, the acceleration stage, and the stabilization stage. The maximum crack width was reduced by 20%–34% for different sample thicknesses. The ratio of the number of cracks to the number of fracture nodes in the reinforced soil was lower than that of the unreinforced soil. This reduction ratio changed further from 5.6% to 24.4% with the increased thickness. The geogrids can effectively reduce the evaporation rate of water and the development rate of the dry-shrinkage cracks in loess. Consequently, the crack distribution in the loess samples is uniform and prevents the formation of large and long cracks. Using a 3D discrete element model, it is feasible to simulate the loess before and after the geogrid reinforcement.

In this study, we investigated the effect of particle size distribution on the shear properties of sand. Direct shear tests were conducted using four types of sand samples with different particle size distributions obtained from standard sand produced by Xiamen ISO Co. Ltd. The results show that the influence of particle size distribution on the internal friction angle was significant. Typically, the internal friction angle increases with increasing the coefficient of non-uniformity (Cu) and decreasing the curvature coefficient (Cc). The discrete element results show that the initial particle size distribution significantly affects the porosity, coordination number, and particle slide fraction. In addition, the grey relation analysis revealed that the sliding fraction and coordination number have the greatest correlation with the internal friction angle. The research results of this study help to understand the changes in particle contact, internal stress, and particle sliding during the shear failure process of sand.

No abstract