This study aims to show how fractal analysis can be effectively used to characterize the pore structure of porous tar-rich coal. In this study, tar-rich coal pores were obtained by mercury intrusion porosimetry (MIP). The results showed that the sample had a high porosity and large pore diameter after pyrolysis, and the porosity of tar-rich coal was more than 35 at 600C. The pore-throat ratio at high temperature was large, resulting in the high mercury retention rate. The pore distribution curves of samples at pyrolysis temperatures of 500 and 600C were unimodal, and those of samples at room temperature and 150, 300, and 400C were bimodal. The models for calculating fractal dimension based on MIP include Menger sponge model and thermodynamic model. Experiments show that the Menger sponge method is more reasonable when the pore size is less than 50μm and greater than 350nm. For the fractal dimension calculation of the whole pore curve section, the thermodynamic method was more reasonable. The use of fractal analysis in conjunction with the results of classical characterization methods leads to a better understanding of pore evolution in the pyrolysis process of tar-rich coal. The average fractal dimension could also be used as a valid parameter to monitor the textural evolution of the coals.

With the increase in transportation emissions, road diseases in the saline soil area of Jilin Province have become a problem that requires serious attention. In order to improve the subgrade performance, the structural yield strength (SYS) of remolded soil and its factor sensitivity are investigated in this study. Saline soils in Western Jilin are structural in the sense that the bonding strength of soil skeleton is mainly provided by the solidification bond formed by a physicochemical interaction between particles. Its SYS is influenced by its cementation type, genetic characteristics, original rock structure, and environment. Because of the high clay content in Zhenlai saline soil, the specific surface area of soil particles is large, and the surface adsorption capacity of soil particles is strong. In addition, the main cation is Na⁺. The cementation strength of bound water film between soil particles is thus easily affected by water content and salt content, and compaction is also an important factor affecting the strength of soil. Therefore, in this study, the back-propagation neural network (BPNN) model and a support vector machine (SVM) are used to explore the relationship of saline soil’s SYS with its compactness, water content, and salt content. In total, 120 data points collected by a high-pressure consolidation experiment are applied to building BPNN and SVM model. For eliminate redundant features, Pearson correlation coefficient (r_PCC) is used as an evaluation standard of feature selection. The K-fold cross-validation method was used to avoid over fitting. To compare the performance of the BPNN and SVM models, three statistical parameters were used: the determination coefficient (R²), root mean square error (RMSE), and mean absolute percentage deviation (MAPD). The result shows that the average values of R², RMSE, and MAPD of the BPNN model are superior to the values of the SVM. We conclude that the BPNN model is slightly better than the SVM for predicting the SYS of saline soil. Thus, the BPNN model is used to analyze the factor sensitivity of SYS. The results indicate that the influence degrees of the three parameters are as follows: water content > compactness > salt content. This study can provide a basis for estimating the structural yield pressure of soil from its basic properties, and can provide a new way to obtain parameters for geotechnical engineering, ensuring safety while maintaining symmetry in engineering costs.

According to laboratory tests of soil samples of Wangyan highway landslide, the mechanism of formation of landslide and the degree of sensitivity of various factors to slope stability are analyzed. It is found that the landslide is destroyed by the properties of expansive soil, the existence of water in the cracks, the loading of artificial filling, and the traction of old landslide. The soil samples were tested for SEM and MIP tests by lyophilization, and the particle morphology, the mode of combination, porosity, and connectivity of the sliding zone soil were observed by a scanning electron microscope. Results show that the sliding zone developed many microfissures and the clay minerals arranged tightly, the pore of μm was 60% in undisturbed soil, and the pores of different sizes were distributed uniform in reconstituted soil. The undisturbed soil had typical nonlinear rheological property; The deformation rate of reconstituted was bigger; When the load was 50 kPa and 200 kPa, an expansion phenomena occurred in the sliding zone, which indicated that microstructure could influence the deformation. The strength attenuation of expansive soil slope due to the high content of montmorillonite in the sliding body and the high water content in the cracks are two major factors of the Wangyan highway landslide. Based on the results of previous studies, the , , and values of fitting parameters of Fredlund-Xing soil-water characteristic curve are predicted by using the basic physical properties of soil. It is found that the air intake value and residual suction value of filled soil (loose and broken) and completely weathered sandstone are small, and the water holding capacity in the middle suction range is relatively good. Then, the finite difference software Flac3D was used to build a three-dimensional geological model. The influence of water content, highway load, filling weight, and slope angle on slope stability is considered comprehensively. The order of sensitivity of slope stability about various factors is as follows: . The results of research can provide a scientific basis for the treatment, protection, and reinforcement of the Wangyan highway landslide.

In order to study the bearing characteristics and failure mechanism of the rigid antislide pile under horizontal load, the stress of rigid antislide pile under transverse axial large displacement load is analyzed by using elastic-plastic theory, finite element analysis, and model test. The theoretical formula of the proximal plastic earth pressure near the pile with the depth of soil under the horizontal force is obtained. The results show that the standard is insensitive to the variation of soil parameters and the influence of soil parameters on allowable soil resistance in front of pile should be considered. With the increase of the horizontal force of the pile top, the soil near the pile is destroyed in this process gradually, which is the decline of the cross section of the maximum soil resistance of the pile. When the horizontal displacement of pile top is 20mm and 70mm, the soil resistance value and the ultimate soil resistance value in front of the pile can be selected, respectively. The plastic zone develops to the front and bottom of the pile at the same speed, at an angle of 45 with the direction of gravity. When the displacement reaches 34mm, the plastic zone develops to the deeper depth obviously. The results can provide a theoretical basis for the design and application of antislide piles during the process of slope protections.