Abstract:A large-scale immersion experiment was carried out to assess the collapsibility characteristics of loess in Bu Li village located in the Weibei Loess Tableland, and the seepage characteristics and collapsibility evolution of loess were determined. The effects of void ratio, natural moisture content, material composition, and microstructure evolution on the loess collapsibility were characterized by X-ray diffraction, scanning electron microscopy, and water-soluble salt analysis to elucidate the collapsibility … Show more
“…These deposits are extensively found within China, particularly in the Xian, Shanxi, and Henan provinces [30][31][32][33]. The main characteristics of loess, which is regarded as a problematic soil, are wet subsidence and its associated structural problems with the performance of geotechnical infrastructures constructed with them or within them [34,35]. The accuracy of loess parameters is crucial for engineering stability analysis and disaster assessment [36,37] for assuring the sustainability of infrastructures designed in problematic loess deposits.…”
The shear strength parameters of loess samples are determined from conventional triaxial shear test results and used in the rational design of sustainable geotechnical infrastructures. However, the rubber membrane that is used in the triaxial shear apparatus for applying the all-around pressure to the test specimen has a significant influence on the measured shear strength parameters. In this paper, remolded and undisturbed unsaturated loess samples from northwest China are used in a comprehensive testing program to determine the shear strength from triaxial tests and understand the influence of a rubber membrane. The results show that the measured undrained cohesion from unconsolidated undrained triaxial tests on unsaturated soil specimens with and without a rubber membrane are significantly different. In this study, differences in the shear strength with and without a rubber membrane are assessed from shear strength index values that can be determined from undrained cohesion and the internal friction angle derived from conventional triaxial tests. Experimental results suggest that predominant changes arise mainly in the undrained cohesion values. The change rate of shear strength indices values of undisturbed loess shows a strong correlation with its water content; however, it is weak for remolded loess. The correlation coefficient between error and measured values of all shear strength indices is more than 0.8. Empirical correction relationships for triaxial shear tests with a rubber membrane for three different types of loess were established from the investigations. The simple approach used in this study can be used as a reference to apply corrections to the measured undrained cohesion values of unsaturated loess samples from northwest China.
“…These deposits are extensively found within China, particularly in the Xian, Shanxi, and Henan provinces [30][31][32][33]. The main characteristics of loess, which is regarded as a problematic soil, are wet subsidence and its associated structural problems with the performance of geotechnical infrastructures constructed with them or within them [34,35]. The accuracy of loess parameters is crucial for engineering stability analysis and disaster assessment [36,37] for assuring the sustainability of infrastructures designed in problematic loess deposits.…”
The shear strength parameters of loess samples are determined from conventional triaxial shear test results and used in the rational design of sustainable geotechnical infrastructures. However, the rubber membrane that is used in the triaxial shear apparatus for applying the all-around pressure to the test specimen has a significant influence on the measured shear strength parameters. In this paper, remolded and undisturbed unsaturated loess samples from northwest China are used in a comprehensive testing program to determine the shear strength from triaxial tests and understand the influence of a rubber membrane. The results show that the measured undrained cohesion from unconsolidated undrained triaxial tests on unsaturated soil specimens with and without a rubber membrane are significantly different. In this study, differences in the shear strength with and without a rubber membrane are assessed from shear strength index values that can be determined from undrained cohesion and the internal friction angle derived from conventional triaxial tests. Experimental results suggest that predominant changes arise mainly in the undrained cohesion values. The change rate of shear strength indices values of undisturbed loess shows a strong correlation with its water content; however, it is weak for remolded loess. The correlation coefficient between error and measured values of all shear strength indices is more than 0.8. Empirical correction relationships for triaxial shear tests with a rubber membrane for three different types of loess were established from the investigations. The simple approach used in this study can be used as a reference to apply corrections to the measured undrained cohesion values of unsaturated loess samples from northwest China.
“…(Han, 2022) pointed out that the failure of sandy loess is mostly induced by vibration collapse. Typical loess zone disasters have the highest complexity and the most complex mechanism, and most of their damage is caused by various natural disasters induced by water (Lv et al, 2023;Xie et al, 2023;;The geological disasters occurring in the clay belt are mostly cumulative deformation (Tang et al, 2011). For different damage, scholars have in-depth research and treatment measures.…”
The distribution law of dust particles under the action of wind is of great significance for the transport and settlement of loess in ancient environment and the study of modern sand and dust on environmental pollution. Based on wind tunnel test, physical model and numerical simulation, the particle transport deposition process was studied, and the following conclusions were obtained through mutual verification: (1) The particle size information in wind tunnel test shows that the smaller the particle size is. (2) Through the physical model, it is deduced that the ideal transport distance of dust particles is inversely proportional to the second square of particle diameter, which is well verified by the experimental results in this paper; (3) In the experiment, the grain size distribution curve of sedimentary particles is bimodal, which is a strong proof that the source area of particles and the transport path are the same in the loess area; The curve is a right-sided curve of normal distribution, which is the same as the grain gradation curve of undisturbed loess in northwest China. We believe that the reason for this trend is the different deposition rates of coarse and fine particles. (4) In the numerical simulation, we observed the influence of rising wind and other conditions on the distribution of sedimentary particles, which has certain reference significance for the actual dust transport process.
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