Currently, studies on the permeability evolution characteristics of overlying aquiclude protective layers caused by coal mining focus on single lithological protective layers and assume the permeability coefficient remains constant. However, these studies fail to consider the variation characteristics of the combination protective layer structure and permeability coefficient. Therefore, an analytical method is proposed to study coal seam leakage under mining conditions in the blown-sand beach region based on the structure and permeability coefficient of the combination protective layer. First, the stress path of the overlying combination aquiclude under coal mining disturbance is comprehensively considered. Based on this, triaxial loading and unloading seepage creep experiments are conducted with different proportions of overlying combination aquiclude. The analytical relationship between the permeability coefficient of the samples and loess proportion, stress level, and soil depth in the stress recovery stage is determined, leading to the establishment of a creep permeability coefficient evolution model for the overlying combination aquiclude of the coal seam under the stress path of coal mining. Second, the creep permeability coefficient evolution model is integrated with a fusion algorithm in COMSOL numerical simulation software. Numerical simulations are then performed to examine the evolution law of phreatic leakage during coal seam mining and recovery, revealing a relationship curve in which leakage gradually decreases over time before stabilizing in the post-mining recovery stage. Finally, based on mathematical and statistical methods, a phreatic leakage evolution model is developed for both mining and post-mining stages to provide a theoretical basis for environmental protection.

The physicochemical combination method (PCCM) is a new integrated method for treating and reusing large volumes of slurry-like mud (MS). To study the effects of freezing-thawing (FT) cycles on the mechanical properties of MS treated by the PCCM, unconfined compression tests (UCTs) and microstructural tests are both conducted on PCCM-treated MS samples with different combinations of FT cycles, initial water contents (wei), and cementitious binder contents (wc). The experimental results indicate that the unconfined compressive strength (UCS) and the elastic modulus (E) of PCCM-treated MS decrease exponentially when the FT cycles increase from 0 to 15. For the PCCM-treated MS samples subjected to 15 FT cycles, the reduction degree of their strength, as well as deformation resistance, is more sensitive to the variation of wc compared to that of wei. Meanwhile, the UCS and E of PCCM-treated MS samples are higher than those of the corresponding MS samples treated by the conventional cement solidification method (CCSM). The superior resistance to FT cycles of PCCM-treated MS is attributed to the presence of APAM, which not only facilitates the aggregation of soil particles but also enhances the dewatering efficiency of MS. Notably, the E/UCS value of CCSM-treated MS is 1.25 times larger than that of PCCM-treated MS, indicating the application of PCCM can significantly enhance the toughness of the treated MS.

The spatial combination of stratigraphic structural elements significantly influences the overburden damage caused by mining. However, existing studies have not yet clearly revealed the specific relationship between these elements and overburden damage, nor have they intuitively demonstrated the spatial distribution characteristics of overburden damage. In response, this paper proposes a comprehensive analysis method that can visually and quantitatively characterize the spatial distribution of overburden damage. This method combines stratigraphic model generalization, damage mechanics modeling, numerical simulation, and color mapping characterization. This method was applied to analyze the mining damage characteristics of different structural overburdens in the Yushenfu mining area. The analysis revealed a prevalent stratigraphic combination pattern of sand layers, soil layers, and two sections of mudstone and fine sandstone interbeds. The study shows that mining height and bedrock-soil ratio are important stratigraphic structural factors that affect the fracture/mining height ratio. The ranking of elastic modulus loss and spatial loss in various damaged areas of the overburden is consistent, in the following order: collapse zone > fracture zone > bending subsidence zone. Furthermore, this method reveals the mechanism of increased residual expansion in the overburden caused by coal mining, which, in turn, leads to surface collapse. This method provides a theoretical basis for implementing targeted engineering disposal and safety measures.

In this research, an energy formulation is proposed for the evaluation of pore pressure generation, incorporating the influence of the initial state of static stresses, both normal and shear, prior to cyclic loading. The proposed model focuses on obtaining a law of evolution of pore pressures under cyclic loading in saturated soils regardless of their susceptibility or not to liquefaction. The energy approach developed in this research extends previous energy based models developed for granular soils (susceptible to liquefaction and without initial static shear stress) incorporating: a) the integration in the formulation and interpretation of both the work dissipated and consumed during the dynamic process; b) the normalization of the formulation considering initial static stresses both normal and shear; c) obtaining and validating the model parameters with conventional tests of cyclic shearing equipment. The proposed model was validated with 116 cyclic simple shear tests under different in situ vertical effective stresses and different combinations of static and cyclic shear stresses. However, the model can be easily calibrated for other soils with cyclic simple shear tests without static shear stress, widely used in laboratories with dynamic equipment.

Wildfires lead to socio-economic and environmental impacts. These impacts include hydrological instability, which can cause severe damage, especially where infrastructures are present. Post-rehabilitation measures can be useful in reducing or preventing erosion or hydrogeological risks. Decision-makers are called on to prioritize post-fire intervention areas and allocate public funds for this purpose. This work focuses on the assessment of erosion and hydrological risk potential in forested slope areas affected by wildfire using a Multi-Criteria Decision Analysis (MCDA) approach integrated with a GIS environment on a regional scale. Expert perception was considered using the pairwise comparison method as part of the Analytical Hierarchy Process (AHP). This allows expert stakeholders to rank relevant criteria, providing a quantitative metric (weight) for qualitative data. Two MCDA methods are used and compared: Weighted Linear Combination (WLC) and Ordered Weighted Averaging (OWA). Fire frequency, slope (gradient and length), and proximity to infrastructures were found to be the most important factors by the stakeholders. The WLC method provides evidence classified into high and moderate suitability class areas characterized by high values for fire frequency or slope gradient. Conversely, the OWA method, ranging from low to high risks, makes it possible to adapt the method and obtain a range of suitability maps. Novelties of the MCDA-GIS combined methodology adopted in this work are its application on a regional scale and the combination of vulnerability and driving-force factors (namely presence of grey infrastructures, fire frequency). The MCDA-GIS methodology can be suitable for public administrations in that it allows for mapping a regional area more quickly and thus facilitates sector planning.

To address prominent issues in the spring soil removal process for wine grapes in northern China, such as incomplete soil clearing, vine damage, and low operational efficiency, a dual-sided soil removal machine combining scraping, rotary, and vibration functions was designed and developed. The machine primarily consists of a gantry frame, rotary soil components, scraping components, and vibrating components. Using EDEM 2020 discrete element software analysis and Design-Expert 13 orthogonal experiments, a three-factor, three-level orthogonal simulation experiment was conducted, with rotary soil component speed, scraping component angle, and vibrating component frequency as test factors and soil removal rate as the evaluation index. The optimal operating parameters were determined: rotary soil component speed at 720.6 r/min, scraping component angle at 42.4 degrees, and vibrating component frequency at 179.1 Hz, yielding a soil removal efficiency (K value) of 83.48% and the best simulation results. A physical prototype was manufactured, and field experiments were conducted, resulting in an actual soil removal rate of 76.81%, with a deviation of 7.09% from the simulation results. The field test results were consistent with the simulation data, and the exposed vines in the field after soil removal met the operational requirements for actual production. The research outcomes of this machine provide a reference for the further development of dual-sided soil removal equipment for wine grape vines.

An adequate provision of essential plant nutrients to cash crops such as potatoes not only ensures higher productivity and desired tuber quality but also promotes better development under unfavorable environments. The present trial was planned to investigate and understand the effects of various treatments of mineral fertilizers viz., nitrogen (N), phosphorus (P), and potassium (K) (NPK) in individual and combined forms on potato crops. Experimental treatments were comprised various combinations viz., control (no addition of any type of fertilizer); N = 150 kg ha-1; P = 75 kg ha-1; K = 225 kg ha-1; NP = N + P; NK = N + K; PK = P + K; NPK = N + P + K in soil. The results indicated that different combinations of NPK fertilizer in individual and combined forms not only influence the growth attributes such as stem diameter (83.96%) and tuber yields (180.09%) but also enhance photosynthetic attributes by improving the total chlorophyll (135.63%), carotenoids contents (143.75%), and potato quality by increasing tuber starch contents (78.75%), plant sucrose contents (52.86%) and sucrose enzyme activity (69.68%). A linear decrease in the lipid per oxidation attributes was observed where a combined application of NPK was applied. It was obvious that all the yield and quality attributes were enhanced by the combined application of NPK fertilization and then decreased gradually with the individual application of NPK fertilization. In contrast, though, the P and K application in combined form showed inferior response as compared to NP and NK fertilization. A clear and significant change in potato plants was observed under the various types of treatments especially related to the content and uptake of NPK in plants. Moreover, a highly significant relationship was observed between the balanced combination of NPK fertilization with tuber quality. This study underscores the importance of balanced fertilization practices in bolstering growth, yield, tuber quality, and antioxidative defense mechanisms and mitigating oxidative damage in potato crops.

Background: The current focus is largely on whole course medical management of coronavirus disease-19 (COVID-19) with real-time polymerase chain reaction (RT-PCR) and radiological features, while the mild cases are usually missed. Thus, combination of multiple diagnostic methods is urgent to understand COVID-19 fully and to monitor the progression of COVID-19. Methods: laboratory variables of 40 mild COVID-19 patients, 30 patients with community-acquired pneumonia (CAP) and 32 healthy individuals were analyzed by principal component analysis (PCA), Kruskal test, Procrustes test, the vegan package in R, CCA package and receiver operating characteristic to investigate the characteristics of the laboratory variables and their relationships in COVID-19. Results: The correlations between the laboratory variables presented a variety of intricate linkages in the COVID-19 group compared with the healthy group and CAP patient group. The prediction probability of the combination of lymphocyte count (LY), eosinophil (EO) and platelets (PLT) was 0.847, 0.854 for the combination of lactate (LDH), creatine kinase isoenzyme (CK-MB), and C-reactive protein (CRP), 0.740 for the combination of EO, white blood cell count (WBC) and neutrophil count (NEUT) and 0.872 for the combination of CK-MB and P. Conclusions: The correlations between the laboratory variables in the COVID-19 group could be a unique characteristic showing promise as a method for COVID-19 prediction and monitoring progression of COVID-19 infection.

In order to solve the problem of low efficiency and potential damage in the separation of Gentiana roots from soil, a reciprocating adjustable striking-vibration combined device was designed, along with its performance testing. The ranges of working parameters for the vibration mechanism, striking mechanism, and adjustable reciprocating mechanism were determined through dynamic analysis of the mechanisms and materials. The effects of vibration frequency (X1), crank speed (X2), and screw feed speed (X3) on the threshing efficiency (Y1) and damage percentage (Y2) were studied using a ternary quadratic regression orthogonal combination experimental method, combined with response surface analysis to explore the interaction effects of these factors on the indicators. A regression model was established through variance analysis. The significant factors affecting Y1 were X2, X3, and X1 in that order, while the significant factors affecting Y2 were X1, X3, and X2. In the interaction of factors, X1X2 significantly affected both Y1 and Y2; X1X3 had extremely significant impact on both Y1 and Y2; and X2X3 had extremely significant impact on Y1. The optimal working parameters for the root- soil separation device of Gentian were determined to be vibration frequency of 6 Hz, crank speed of 204 r/min, and screw feed speed of 15 mm/s. With this combination of parameters, experimental tests yielded a threshing efficiency of 90.8% and a damage percentage of 5.9%. The relative errors compared with the theoretical optimization results were less than 5%. This study meets requirements for the root-soil separation of Gentiana.

In order to explore the mechanical properties of cement-soil wrapped pile support system in soil-rock combination foundation pit support. In this paper, based on a deep foundation pit project in Qingdao, the horizontal displacement monitoring test of cement-soil wrapped pile support system was carried out. Combined with ABAQUS finite element numerical simulation, the foundation support model of cement-soil wrapped pile in soilrock combination foundation was established. The variation rule of bending moment and displacement of cement-soil wrapped pile under different influencing factors is explored, And the reasonable position of the micro steel pipe piles in the cement-soil pile is clarified. The results of the study show that the micro steel pipe piles have the best support with less horizontal displacement when they are located on the excavation side of the foundation pit. With the gradual increase of excavation depth, the horizontal stress of the soil basically increases linearly, which is consistent with the change rule of active soil pressure along the depth direction. Increasing the strength of cement-soil can significantly improve the deformation resistance of the supporting structure. The research results can provide reference for the design and construction of foundation support for soil-rock combination foundations.