Gunung Bromo Education Forest is a forest that functions as a buffer area to maintain the balance of the surrounding area. However, the undulating to hilly topography, the presence of rivers, and land management for annual crops can make the area vulnerable to erosion-induced degradation. This research aims to analyze and classify the erosion hazard level in Gunung Bromo Education Forest and analyze the relationship between research parameters and erosion in Gunung Bromo Education Forest. Erosion was predicted using the MUSLE method. This research used an explorative-descriptive method incorporating a survey and laboratory analysis. Furthermore, data analysis used was Analysis of Variance (ANOVA), Duncan's Multiple Range Test (DMRT) at a 5% significance level, and Pearson correlation test. The results showed that Gunung Bromo Education Forest erosion ranged from 0.025 to 78.36 t ha(-1)y(-1). The erosion hazard level in Gunung Bromo Education Forest is in the very light to heavy class and is dominated by the light class. The factors of erosivity (R), erodibility (K), slope (LS), and crop management (C) are positively correlated with erosion values. The conservation factor (P) is negatively correlated with erosion values. Making remedial efforts according to the erosion hazard level is important to avoid greater damage.

Freeze-thaw cycles (FTC) influence soil erodibility (K-r) by altering soil properties. In seasonally frozen regions, the coupling mechanisms between FTC and water erosion obscure the roles of FTC in determining soil erosion resistance. This study combined FTC simulation with water erosion tests to investigate the erosion response mechanisms and key drivers for loess with varying textures. The FTC significantly changed the mechanical and physicochemical characteristics of five loess types (P < 0.05), especially reducing shear strength, cohesion, and internal friction angle, with sandy loam exhibiting more severe deterioration than silt loam. Physicochemical indices showed weaker sensitivity to FTC versus mechanical properties, with coefficients of variation below 5 %. Wuzhong sandy loess retained the highest K-r post-FTC, exceeding that of the others by 1.04 similar to 2.25 times, highlighting the dominant role of texture (21.37 % contribution). Under different initial soil moisture contents (SMC), K-r increased initially and then stabilized with successive FTC, with a threshold effect of FTC on K-r at approximately 10 FTC. Under FTC, the K-r variation rate showed a concave trend with SMC, turning point at 12 % SMC, indicating that SMC regulates freeze-thaw damage. Critical shear stress exhibited an inverse response to FTC compared to K-r, displaying lower sensitivity. The established K-r prediction model achieved high accuracy (R-2 = 0.87, NSE = 0.86), though further validation is required beyond the design conditions. Future research should integrate laboratory and field experiments to expand model applicability. This study lays a theoretical foundation for research on soil erosion dynamics in freeze-thaw-affected areas.

The present paper sets out a comparative analysis of carbon emission and economic benefit of different performance gradients solid waste based solidification material (SSM). The macro properties of SSM were the focus of systematic study, with the aim of gaining deeper insight into the response of the SSM to conditions such as freeze-thaw cycles, seawater erosion, dry-wet cycles and dry shrinkage. In order to facilitate this study, a range of analytical techniques were employed, including scanning electron microscopy (SEM), X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP). The findings indicate that, in comparison with cement, the carbon emissions of SSM (A1) are diminished by 77.7 %, amounting to 190 kg/t, the carbon-performance ratio (24.4 kg/ MPa), the cost-performance ratio (32.1RMB/MPa) and the carbon-cost ratio (0.76kg/RMB) are reduced by 86 %, 56 % and 68 % respectively. SSM demonstrated better performance in terms of freeze-thaw resistance, seawater erosion resistance and dry-wet resistance when compared to cement. The dry shrinkage value of SSM solidified soil was reduced by approximately 35 % at 40 days compared to cement solidified soil, due to compensatory shrinkage and a reduction in pores. In contrast to the relatively minor impact of seawater erosion and the moderate effects of the wet-dry cycle, freeze-thaw cycles have been shown to cause the most severe structural damage to the micro-structure of solidified soil. The conduction of durability tests resulted in increased porosity and the most probable aperture. The increase in pores and micro-structure leads to the attenuation of macroscopic mechanical properties of SSM solidified soil. The engineering application verified that with the content of SSM of 50 kg/m, 4.5 % and 3 %, the strength, bearing capacity and bending value of SSM modified soil were 1.9 MPa, 180 kPa and 158, respectively in deep mixing piles, shallow in-situ solidification, and roadbed modified soil field.

In the northwestern saline soils and coastal areas, cement soil (CS) materials are inevitably subjected to various factors including salt erosion, dry-wet cycle (DWC), temperature fluctuations and dynamic loading during its service life, which the coupling effect of these unfavourable factors seriously threatened the durability and engineering reliability of CS materials. Additionally, combined with the substantially extensive application prospects of rubber cementitious material, as a resource-efficient civil engineering material and fibre-reinforced composites, consequently, in order to address aforementioned issues, this investigation proposed to consider the incorporation of rubber particles composite basalt fiber (BF) to CS materials as an innovative engineering solution to effectively enhance the mechanical and durability properties of CS materials for prolonging its service life. In this study, sulphate ions were utilized to simulate external erosive environment and basalt fibre rubber cement soil (BFRCS) specimens were subjected to various DWC numbers (0, 1, 4, 7, 11 and 15) in diverse concentrations (0 g/L, 6 g/L and 18 g/L) of Na2SO4 solution, and specimens that had completed the corresponding DWC number were then conducted both unconfined and dynamic compressive strength tests simultaneously to analyze static and dynamic stress-strain curves, static and dynamic compressive strength, apparent morphological deterioration characteristics and energy absorption properties of BFRCS specimens. Furthermore, further qualitative and quantitative damage assessments of pore distribution and microscopic morphology of BFRCS specimens under various DWC sulphate erosion environments were carried out from the fine and microscopic perspectives through pore structure test and scanning electron microscopy (SEM) test, respectively. The test results indicated that the static, dynamic compressive strength and specific energy absorption (SEA) of BFRCS specimens exhibited a slight increase followed by a progressive decline as DWC number increased. Additionally, compared to 4 mm BFRCS specimens, those with 0.106 mm rubber particle size demonstrated more favorable resistance to DWC sulphate erosion. The air content, bubble spacing coefficient and average bubble chord length of BFRCS specimens all progressively grew as DWC number increased, while the specific surface area of pores gradually decreased. The effective combination of BF with CS matrix significantly diminished pores and weak areas within specimen, and its synergistic interaction with rubber particles efficiently mitigated the stresses associated with expansive, contraction, crystallization and osmosis subjected by specimen. Simultaneously, more ettringite (AFt) had been observed within BFRCS specimens in 18 g/L sulphate erosive environments. These findings will facilitate the design and construction of CS subgrade engineering in northwestern saline soils and coastal regions, promoting sustainable and durable solutions while reducing the detrimental environmental impact of waste rubber.

To study the failure mechanism of high ductile coagulation (HDC) under sulfate attack in cold saline soil area, cement-based cementing material (cement: fly ash: sand: water reducing agent: water = 1:1:0.72:0.03:0.58) and 2 % polyvinyl alcohol fiber (PVA) were used to prepare HDC sample, to increase the density and ductility of concrete. a 540-day sulfate-long-term immersion test was performed on HDC specimens under two low-temperature curing environments and different sulfate solution concentrations (5 %, 10 %). Using a combination of macro and microscopic methods, according to the principle of energy dissipation, To study the relationship between the evolution of energy (total damage energy U, dissipated energy Uds, elastic strain energy Ues) and the deterioration of strength and the change of pore structure during the compression process of HDC. According to the characteristics of stress-strain curves during HDC compression, the damage evolution characteristics of characteristic stress points during HDC compression are summarized, establish energy storage indicators Kel to evaluate the degree of internal damage of HDC. The results show that during the compression damage process of HDC after long-term soaking in sulfate solution under low temperature environment, Uds and Ues of HDC at characteristic stress points both increase first and then decrease, Kel are reduced first and then increased. The development trend of elastic strain energy and dissipative energy of HDC in 10 % sulfate solution is more drastic than that in 5 % sulfate solution. Compared with the other three groups, the D group energy storage level rises and falls more violently, and the HDC has a smaller ability to resist damage under this condition. Through the study of the correlation between macro and micro changes of HDC in cold saline soil areas and energy evolution, to provide a reference for the stable operation of highly ductile concrete in cold saline soil areas.

This study investigated how soil properties affect levee erosion and foundation scouring by evaluating the behavior of loose and cohesive (mixed) soils beneath a rigid crest under overflow conditions and analyzing flow dynamics within the scoured hole to understand the scouring mechanism. Four cases were examined with varying overtopping depths (Od): LS-FS, LS-FM, and LM-FS, at Od = 2 cm, and LS-FM at Od = 3 cm, where 'L' stands for levee, 'F' for foundation, 'S' for sand (#8), and 'M' for mixed soil (20% silt + 80% sand #8). The results revealed distinct differences among the cases. Notably, erosion of the back slope in the LM-FS case was delayed fourfold compared to LS-FS. In the LS-FM case, breaching of the levee body was delayed by 1.6 times compared to the LS-FS case with a 2 cm overtopping depth. Moreover, different scour hole geometries with complex flow patterns occurred in different timespans. Particle image velocimetry (PIV) was utilized on two physical scoured hole models to analyze the flow behavior within these scoured holes. The PIV analysis revealed the formation of twin eddies, moving in opposite directions and shaped by the nappe flow jet, which was instrumental in the development of the scour holes. This study found that foundation cohesion is more essential than the levee body in delaying levee breaches under rigid crest. Additionally, it revealed the role of twin eddies, especially the levee-side eddy, in increasing the size of the scoured hole upstream and causing levee breaches.

The grouting method plays a critical role in preventing seawater intrusion in submarine tunnels, particularly in regions with highly weathered rock that are susceptible to erosion and shifting seawater. The long-term properties of the strength and impermeability of the grout-soil composite are related to the durability of the tunnel lining structure, which is an important focus of the present research. This study introduces a new method for calculating material ratios to determine the optimal proportions of each component in grout-soil composites. A specialized experimental setup was designed to replicate the erosive conditions of seawater in environments characterized by significant rock weathering. The primary objective of this investigation was to analyze the weakening effects of seawater ions (e.g., Mg2+, SO42-, Cl-) on the grout-soil composite under dynamic seawater flow conditions. Therefore, the influence of water-cement (W-C) ratio, grouting pressure, and erosion duration on the compressive strength and permeability coefficient of the composite was studied. Furthermore, microscopic analyses were conducted to investigate the microstructure and composition of the weakened composite specimens. Finally, the model of damage weakening in grouted composite has been established. The experimental results indicate that the erosive ions (Cl-, SO42-) initially enhance and then weaken the strength and impermeability of the grouted composite, while Mg2+ ions continuously degrade the strength of the composite. Reducing the water-to-cement ratio and increasing the grouting pressure can improve the strength and impermeability of the grouted composite, but once a certain threshold is reached, the enhancement effect becomes negligible. Under different dynamic water environments and with various erosive ions (Cl-, SO42-, Mg2+, and seawater), the compressive strength of the specimens at the end of the erosion process decreased by 25.49%, 31.21%, 50.34%, and 39.70%, respectively, compared to static freshwater. The permeability coefficient increased by 8.5 times, 3.2 times, 5.8 times, and 8.9 times, respectively. As the W/C ratio increased from 0.8 to 1.2, the compressive strength decreased by 27.67%, 38.97%, 65.70%, and 44.58%, respectively, and the permeability coefficient increased by 55.24%, 59.70%, 134.23%, and 44.49%. As the grouting pressure increased from 1.5 MPa to 2.5 MPa, the compressive strength increased by 48.90%, 162.60%, 163.71%, and 48.35%, respectively, while the permeability coefficient decreased by 53.76%, 40.05%, 73.69%, and 32.89%. The findings of this study offer valuable insights into the erosion mechanism of grout-soil composites induced by seawater ions, thereby contributing to enhanced durability and longevity of submarine tunnel infrastructure.

Photovoltaic panels (PVPs) in grasslands are arranged in such a way that they capture rainfall, which subsequently drips from the edges and causes splash erosion in the grassland, ultimately destroying the natural ecological environment. As such, PVPs can adversely affect fragile saline-alkali habitats, but the precise ecological impact of PVP-caused rainfall splash erosion on saline-alkali grassland has yet to be quantified. To explore the impact of splash erosion on the saline-alkali grassland under PVPs, an investigation was performed here on various surfaces commonly underneath PVPs. These surfaces were typical bare saline-alkali surface (B), Suaeda glauca surface (S) and Leymus chinensis surface (L), and all were positioned under PVPs in the Songnen Plain saline-alkali grassland. The soil splash erosion ditch morphology, the plant community status, and the field-measured soil properties of the three underlying surfaces were all analyzed as part of this investigation in accordance with the observed impact of splash erosion on the three underlying surface ecosystems. Ultimately, the splash erosion generated four ditches in the underlying surfaces, with the degree of soil loss ranked from greatest to smallest as B > S > L. According to the RDA results, vegetation coverage was the main factor affecting splash ditch morphology. The vegetation of the S. glauca surface was fragmented following splash erosion. Much of the S. glauca in the splash erosion ditch died, resulting in a 33.47 %-64.66 % reduction in coverage. In contrast, L. chinensis maintained a higher coverage, which means that it inhibited splash erosion more effectively. For the bare surface, the rainfall splash reduced pH and Ec, and S. glauca began to grow along the edge of the ditch. Collectively, our study quantified the impact of rain splash erosion under PVPs in a saline-alkali grassland ecosystem, comparing the difference in the degree of splash erosion among three different underlying surfaces.

Effective erosion mitigation in the Pisha sandstone region is crucial for soil and water conservation in the Yellow River Basin, yet existing vegetation measures are inadequate in water-limited environments. This study examines the application of drought-tolerant biological soil crusts (biocrusts) for erosion control on sandstone slopes and evaluates their erosion-reducing effects under varying coverage and slope conditions through controlled artificial rainfall experiments. Key findings include: (1) biocrusts coverage demonstrated a linear relationship with initial runoff generation time and an exponential relationship with stable runoff generation time. On average, biocrusts delayed initial runoff generation by 396.32 % and extended stable runoff generation time by 153.93 %, thereby increasing the threshold for both initial and stable runoff generation on Pisha-sandstone surfaces. (2) biocrusts reduced runoff volume by an average of 23.89 %, enhanced infiltration volume by 69.19 %, decreased sediment yield by 64.24 %, and lowered the soil erosion modulus by 68.98 %. These results indicated significant promotion of water infiltration and reduction of water erosion. Both effects were positively influenced by coverage and negatively impacted by slope gradient. A critical slope angle of 15 degrees and a critical coverage of 60 % were identified. When the slope was gentle (S 15 degrees), the negative impact of slope predominated, diminishing the positive effect of biocrusts. Additionally, when coverage reached or exceeded 60 %, further increaseing in coverage accelerated the enhancement of infiltration and erosion reduction. Below this threshold, the rate of improvement gradually diminished with increasing coverage. (3) The structural equation model further elucidated that biocrusts mitigate erosion by enhancing the coverage, thereby reducing runoff velocity and modifying the runoff regime. This mechanism effectively dissipates runoff energy, leading to a decreased soil detachment rate and alleviation of soil erosion. Additionally, the relationship between runoff energy and soil detachment rate follows a power function curve, providing an effective method for predicting erosion in Pisha sandstone area. Consequently, biological soil crust technology shows considerable potential for preventing water erosion damage on Pisha sandstone slopes across various gradients.

Internal erosion, which involves the detachment and migration of soil particles from the soil matrix driven by seepage flow, occurs frequently in natural slopes, dikes and many other geotechnical and hydraulic structures. Previous studies primarily focused on soil internal erosion under the isotropic stress state and monotonic hydraulic loadings. However, the soil in engineering practices is under more complicated hydro-mechanical conditions, i.e. anisotropic stress states, and subjected to large and cyclically unsteady hydraulic loadings due to water level fluctuations. Under such conditions, the soil internal erosion process differs significantly from that under the monotonic seepage and isotropic stress states. Therefore, in this study, extensive laboratory tests were carried out to investigate the soil hydro-mechanical behavior subject to high cyclic hydraulic gradients and various stress states. Results show that the soil experienced a gradual internal erosion process under an isotropic or low shear stress state, whereas it experienced rapid erosion followed by a complete failure when the stress ratio (eta) was high. The cyclic hydrodynamic loading accelerated the occurrence of internal erosion due to strong disturbances to the soil structure. The soil pores became continuously connected under high cyclic hydraulic gradients, leading to significant soil deformations due to the collapse of soil force chains by massive particle loss. Additionally, the peak and critical friction angles for all the post-erosion soils decreased considerably and the soil tended to exhibit strain softening behavior after erosion at large cyclic hydraulic gradients.