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The hydro-mechanical behaviour and the constitutive model of sandy mudstone were investigated in this article. Two groups of hydro-mechanical triaxial compression tests were conducted. The results indicated that the inelastic deformation, damage, permeability and failure of the sandy mudstone were affected by the pore pressure and confining pressure. The hydro-mechanical behaviour was characterised by the coupled elastoplastic damage model. This model was based on the effective stress principle and numerical return mapping algorithms. Sensitivity analysis was also performed to examine the effects of four key parameters on the modelling of elastoplastic and damage behaviour. This study can provide a foundation for physical understanding and mathematical modelling of sandy mudstone under coupled loads. [ABSTRACT FROM AUTHOR]

Landslides are one natural disaster in the mountains, causing damage to properties, destruction of infrastructure and loss of life. While landslide deformation and displacement are commonly observed through experimental investigation of the prototype models, this time-consuming approach might involve human errors and inaccurate constitutive models. This study aims to propose a numerical approach based on machine learning for substituting experimental investigation. In pursuit of this objective, the probability-weighted moments (PWMs) for generalised extreme value distribution (GEVD) were implemented to predict the deposit landslide deformation under uniformly increasing rainfall. The deposit landslide of the Dahua was selected as the case study. The accuracy and reliability of the proposed PWM are validated through the maximum likelihood method and the Jenkinson method. The PWM with GEVD is used to derive the progressive failure of the deposit landslide stability under the return period, the pore water pressure variation and the return period's effect. The results show that the proposed solution is suitable for predicting the responses of landslides. Moreover, the results demonstrate the importance of soil density; 30% of the deposited soil was moved when the soil density was 2 g/cm3 besides, and more than 90% were moved at the top of the slope for the soil density equal to 3 g/cm3. [ABSTRACT FROM AUTHOR]

With the overlying load, soft soil particles with high water content can easily embed into miscellaneous fill with large pores, resulting in mutually embedded displacement. This displacement significantly contributes to the total settlement, making its prediction crucial. Considering the final state of mutually embedded displacement as the research object, and taking into account the overlying load, particle size and porosity of the miscellaneous fill, and friction force, a conceptual model based on static equilibrium theory was developed to derive the calculation formula for mutually embedded displacement. The calculation formula indicates that mutually embedded displacement increases with increasing external load, particle size and porosity of the miscellaneous fill, while it increases with decreasing friction coefficient. Furthermore, parameter determination methods in the calculation formula were illustrated using a soft soil moisture content of 40.15% and concrete ball miscellaneous fill. The results indicate that for spherical miscellaneous fill particles, the path coefficient (K) and force coefficient (M) exhibit a linear relationship with particle size, while the lateral friction force (τ) shows a linear relationship with the load. Comparing between the formula's calculations and laboratory tests, it was found that the maximum error is 15.8%, indicating the model's reasonableness and the formula's high predictive accuracy. The derived formula is both convenient and simple, providing theoretical guidance for calculating or predicting the settlement of composite foundations comprising miscellaneous fill and soft soil. [ABSTRACT FROM AUTHOR]

Reservoir impoundment and water level fluctuations often trigger landslides and their secondary disasters, such as potential impulse waves, posing a serious threat to the safety of people along the reservoir and dam areas, causing economic losses and even catastrophic consequences. This study delves into a comprehensive field investigation and monitoring of the engineering geological conditions and deformation mechanisms of the Mogu rock landslide. The impoundment is identified as the primary factor inducing slope deformation, with the cumulative displacement of the sliding body showing no signs of convergence, indicating potential instability. By coupling the elasto-visco-plasticity model and the RNG turbulence model in FLOW-3D, an actual impulse wave disaster near the Lianghekou reservoir dam area is replicated to validate the reliability of the numerical method. Building upon this, a three-dimensional model is established to calculate potential impulse waves generated by the Mogu rock landslide, and the risk to the dam is evaluated. Under different water level conditions, the simulated run-ups of impulse waves do not surpass the dam elevation, demonstrating a satisfactory safety margin. Given the inherent danger of landslide-induced wave disasters, continuous attention is warranted, and preventive measures and suggestions are proposed to address these concerns. Additionally, the study explores the contributions of water level fluctuations to the primary tsunami amplitude, the maximum run-up on the opposite bank and the dam, and the attenuation rate of the tsunami amplitude along the river channel. The results provide significant reference values for the early warning and prevention of comparable reservoir landslides and potential landslide-induced waves worldwide. [ABSTRACT FROM AUTHOR]

Landslide-generated impulse waves (LGIWs) often cause enormous damage. This study proposes a two-way coupled discrete element method (DEM) and smoothed particle hydrodynamics (SPH) method to study the whole hazard chain of LGIWs in mountain reservoirs. In this method, a two-way coupling code is developed to connect the DEM program Particle Flow Code 3D (PFC3D) and the SPH code DualSPHysics for simulating landslide sliding and fluid motion. A series of discretization operations are conducted to transform the DEM balls into discrete balls composed of SPH particles, and the dynamic boundary condition method is used to calculate the interaction forces between fluid and solid phases. This work is validated through a comparative analysis with published physical model experiments. Using the proposed method, the LGIWs induced by the RS deposit in the RM reservoir is simulated. The processes of landslide motion, impulse waves generation, propagation, and running up on the dam are studied. The results show that the proposed method possesses the capability to simulate and predict the hazards of LGIWs. This article represents the first implementation of PFC3D within a coupled DEM-SPH framework to study LGIWs, and provides a valuable way for assessing the associated risks. [ABSTRACT FROM AUTHOR]

Uniaxial/triaxial compression and scanning/backscattered electron microscopy (SEM/BSEM) tests have been conducted in this study to explore the hydro-mechanical (H-M) response and failure mechanism of basalt from Baihetan hydropower station in China. The experimental findings show that the characteristic strengths, deformation behavior, and failure modes of basalt are greatly influenced by confining and pore pressures. Observations from SEM/BSEM tests reveal that the failure mode is due to the development and growth of intergranular/transgranular microcracks. Under H-M loading conditions, the permeability evolution of basalt exhibits nonlinear and distinct characteristics. Additionally, the permeability evolution and failure mode of basalt under the influence of both confining and pore pressures have been discussed. To further describe the H-M response of rocks under loading, continuum damage mechanics theory, in conjunction with strain equivalence and effective stress principles, has been used to establish an entropy distribution-based probabilistic damage constitutive model. To validate the model, the theoretical results have been compared with those obtained from experiments for basalt and other quasi-brittle rock-like materials. The outcome of this study has implications for the engineering design and safety evaluation for structures that lie within rock masses vulnerable to H-M coupling disasters. [ABSTRACT FROM AUTHOR]

When excavating the rock foundation of a hydropower station, it will be affected by the phenomenon of unloading and relaxation, which may increase the risk of stability of the dam foundation engineering system. The dam foundation of Baihetan Hydropower is a columnar jointed rock mass (CJRM), which presents strong brittleness and anisotropy compared to traditional dam foundation rocks. Therefore, this type of rock mass is prone to disturbance to the dam body, structure, etc. during excavation, so it is necessary to accurately evaluate the impact of dam foundation excavation. Establishing a rock mass creep models serve as an effective tool for evaluating such stability but often suffer from significant parameter uncertainty. Digital twin technology, a virtual model, is capable of real-time learning from actual monitoring data obtained from the physical entity to enhance the performance of the built-in mechanistic model. In this study, the researchers employ the classical Burgers constitutive equation as the theoretical framework and integrate it with an ensemble smoother with multiple data assimilation (ESMDA) method based on Bayesian principles, along with displacement monitoring data from the Baihetan Dam foundation, to construct a digital twin model. Within this framework, the researchers analyze the uncertainty of rheological parameters at various measurement points in the Baihetan Dam foundation. Subsequently, the most suitable rheological parameters are selected and incorporated into the constitutive model to obtain displacement estimates, which are then compared with on-site monitoring data. The results demonstrate that the proposed method effectively performs probabilistic parameter estimation and model prediction for rheological mechanics. This research integrates data-driven methods with mechanical principles, offering a reliable approach for assessing the uncertainty of unloading rheological parameters and displacement prediction in dam foundations, thereby providing essential support for the evaluation of excavation projects in the CJRM of the Baihetan Dam foundation. [ABSTRACT FROM AUTHOR]

Large deformations of soft rocks often occur during the excavation and support of the Chuxiong section tunnel in the Yunnan Central Diversion Project. The physical characteristics and creep mechanical properties of the red-bed soft rock were analyzed by combining engineering experience, laboratory tests, and scanning electron microscopy. Furthermore, the creep parameters of the red-bed soft rock were obtained. The issues related to large deformations of deeply buried tunnels with soft and weak rock masses were investigated. Based on construction engineering practice and numerical simulations, characteristics of extrusion damage of deeply buried tunnels with soft and weak rock masses were analyzed. Countermeasures were implemented to solve the problems of large deformations, which can be used as references for the construction of similar soft rock tunnels in the future. [ABSTRACT FROM AUTHOR]

A hybrid smooth particle hydrodynamics (SPH) and shallow water equations (SWEs) model is proposed to simulate landslide-generated waves in river-valley reservoirs. The generation and propagation of impulse waves are simulated using the SPH model and SWEs model, respectively. A well-designed wave generation boundary is established as an interface between the SPH and the SWEs model. The Mohr–Coulomb constitutive model is used to represent the mechanical properties of the landslide. The accuracy of the proposed model are verified by the case of the Dayantang landslide. The proposed method is then applied to predict impulse waves generated by the Wangjiashan landslide. The results show that at the normal water level of 825 m, the maximum sliding velocity is 7.30 m/s, the height of the leading wave is about 7.93 m, and the runup height at the opposite bank is about 5.32 m. The impulse wave reaches the Xiangbiling settlement with a maximum runup height about of 4.54 m, which is higher than the maximum design elevation of 827.50 m of the settlement. It is recommended that disaster risk reduction measures should be implemented in the Wangjiashan landslide. The proposed hybrid SPH-SWEs model provides an effective tool for predicting landslide-generated waves. [ABSTRACT FROM AUTHOR]

Interleukin-6 (IL-6), a pleiotropic cytokine, plays a crucial role in acute stress induced by bacterial infection and is strongly associated with reactive oxygen species (ROS) production. However, the role of IL-6 in the liver of fish after Aeromonas hydrophila infection remains unclear. Therefore, this study constructed a zebrafish (Danio rerio) il-6 knockout line by CRISPR/Cas9 to investigate the function of IL-6 in the liver post bacterial infection. After infection with A. hydrophila, pathological observation showed that il-6−/− zebrafish exhibited milder liver damage than wild-type (WT) zebrafish. Moreover, liver transcriptome sequencing revealed that 2432 genes were significantly up-regulated and 1706 genes were significantly down-regulated in il-6−/− fish compared with WT fish after A. hydrophila infection. Further, gene ontology (GO) analysis showed that differentially expressed genes (DEGs) were significantly enriched in redox-related terms, including oxidoreductase activity, copper ion transport, etc. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed that DEGs were significantly enriched in pathways such as the PPAR signaling pathway, suggesting that il-6 mutation has a significant effect on redox processes in the liver after A. hydrophila infection. Additionally, il-6−/− zebrafish exhibited lower malondialdehyde (MDA) levels and higher superoxide dismutase (SOD) activities in the liver compared with WT zebrafish following A. hydrophila infection, indicating that IL-6 deficiency mitigates oxidative stress induced by A. hydrophila infection in the liver. These findings provide a basis for further studies on the role of IL-6 in regulating oxidative stress in response to bacterial infections. [ABSTRACT FROM AUTHOR]

In constructing hydraulic tunnels, construction disturbances and complex geological conditions can induce variations in the surrounding rock parameters. To navigate the complex non-linear interplay between rock material parameters and tunnel displacement during construction, this study proposes a hybrid learning model. It employs particle swarm optimization (PSO) to refine the hyperparameters of the eXtreme Gradient Boosting (XGBoost) technique. Sensitivity analysis and inversion of rock parameters is performed by using orthogonal design and the Sobol method to analyze the sensitivity of environmental and rock material factors. The findings indicate that the tunnel depth, elastic modulus, and Poisson ratio are particularly sensitive parameters. Mechanical parameters of the rock mass, identified through sensitivity analysis, are the focal point of this research and are integrated into a three-dimensional computational model. The resulting tunnel displacement calculations serve as datasets for the inversion of the actual engineering project's surrounding rock mechanical parameters. These inverted parameters were fed into the FLAC3D software (version 7.0), yielding results that align closely with field measurements, which affirms the PSO-XGBoost model's validity and precision. The insights garnered from this research offer a substantial reference for determining rock mass parameters in tunnel engineering amidst complex conditions. [ABSTRACT FROM AUTHOR]

This study investigates the dynamic mechanical properties of weathered granite under high strain rates using dynamic compression tests conducted with the Split Hopkinson Pressure Bar (SHPB) method. The objective is to comprehensively understand the behavior of weathered granite, including its failure mechanisms and energy dissipation characteristics. The test results show that the dynamic compression strength of weathered granite increases from 87.95 MPa to 192.51 MPa, as the strain rate is increased from 43.69 s–1 to 137.08 s–1, the dynamic strength increase factor (DIF) has a linear relationship with the strain rate. The obtained dynamic stress-strain curves during impact loading exhibit distinct stages, namely elastic behavior, crack expansion, and plastic deformation up to failure. Cracks propagate directionally along the principal stress direction, resulting in tensile failure and progressive fracture from edges to interior. Furthermore, the absorption energy, transmission energy, and reflection energy of weathered granite samples exhibit distinct relationships with incident energy, following linear, logarithmic, and quadratic patterns, respectively. The extent of fracture significantly affects important parameters such as wave impedance, reflection coefficient, and transmission coefficient. Using energy theory and statistical damage theory, a dynamic statistical damage constitutive model for weathered granite was developed. The model was validated by comparing the theoretical results with the test curves. The obtained results contribute valuable insights into the dynamic mechanical properties and constitutive model of subsea rock, providing theoretical support for marine engineering construction. [ABSTRACT FROM AUTHOR]

DNA methylation is an important epigenetic modification that has been shown to be associated with responses to non-biological stressors. However, there is currently no research on DNA methylation in response to environmental signals in shrimp. In this study, we conducted a comprehensive comparative analysis of DNA methylation profiles and differentially expressed genes between two strains of Litopenaeus vannamei with significantly different cold tolerance through whole genome bisulfite sequencing (WGBS) and transcriptome sequencing. Between Lv-C and Lv-T (constant temperature of 28 °C and low temperatures of 18 °C and 10 °C) under cytosine-guanine (CG) environments, 39,100 differentially methylated regions (DMRs) were identified, corresponding to 9302 DMR-related genes (DMRGs). The DMRs were mainly located in the gene body (exons and introns). Gene Ontology (GO) analysis showed that these DMRGs were significantly enriched in cell parts, catalytic activity, and metabolic processes. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed significant enrichment of these DMRGs in pathways such as proteasome (ko03050), oxidative phosphorylation (ko00190), mTOR signaling pathway (ko04150), fatty acid metabolism (ko01212), and fatty acid degradation (ko00071). The comprehensive results suggested that L. vannamei mainly regulates gene expression in response to low temperatures through hypermethylation or demethylation of some genes involved in thermogenesis, glycolysis, the autophagy pathway, the peroxisome, and drug metabolism pathways. These results provide important clues for studying DNA methylation patterns and identifying cold tolerance genes in shrimp. [ABSTRACT FROM AUTHOR]

In earthquake engineering, loading strain rate has an important influence on the mechanical properties of rock. A systematical experimental study is conducted to investigate the strain rate effect of limestone, obtained from a post-earthquake Hongshiyan landslide area in southwest China. Basic mechanical parameters, deformation failure patterns, and energy characteristics are studied. The results show that an increase in the strain rate leads to an exponential increase in the peak stress and a logarithmic increase in the elastic modulus. Rock failure patterns, including axial splitting failure, combined shear-split failure, and shear failure, are dominantly controlled by the influence of confining pressure. Energy curves can be divided into four stages: initial compression, elastic, yield, and post-peak stage. The proportion of elastic energy and dissipated energy increase and decrease with the increase of strain rate, respectively. An obvious threshold divided the stress-strain curve of pre-peak period into the stable part and rapid growth part. A full-range strain rate model is proposed to fit the dynamic increasing factor, and the controlling parameters can be obtained directly, which overcomes the problem of discontinuity at the junction of middle strain rate and high strain rate. [ABSTRACT FROM AUTHOR]

Oxygen homeostasis is an important organizing principle for understanding development, physiology, disease, and evolution. Under various physiological and pathological states, organisms experience oxygen deficiency or hypoxia. FoxO4 has been recognized as an important transcriptional regulator involved in a variety of cellular functions, including proliferation, apoptosis, differentiation, and stress resistance, but its role in hypoxia adaptation mechanisms in animals is not so clear. To explore the role of foxO4 in the hypoxia response, we detected the expression of foxO4 and the regulatory relationship between Hif1α and foxO4 under hypoxic conditions. It was found that the expression of foxO4 was up-regulated in ZF4 cells and zebrafish tissues after hypoxia treatment, and Hif1α could directly target the HRE of the foxO4 promoter to regulate foxO4 transcription, indicating that foxO4 was involved in the hypoxia response by the Hif1α-mediated pathway. Furthermore, we obtained foxO4 knockout zebrafish and found that the disruption of foxO4 increased the tolerance to hypoxia. Further research found that the oxygen consumption and locomotor activity of foxO4−/− zebrafish were lower than those of WT zebrafish, as was true for NADH content, NADH/NAD+ rate, and expression of mitochondrial respiratory chain complex-related genes. This suggests that disruption of foxO4 reduced the oxygen demand threshold of the organism, which explained why the foxO4−/− zebrafish were more tolerant to hypoxia than WT zebrafish. These results will provide a theoretical basis for further study of the role of foxO4 in the hypoxia response. [ABSTRACT FROM AUTHOR]

To enrich understanding of how fluid flows through the natural filled jointed rock, the permeability experiments of the natural filled jointed dacite rock under repeated loading and unloading conditions are carried out. Experimental results show that the response of permeability of filled jointed dacite rock to confining pressure under repeated loading and unloading conditions is considered as porous media. Permeability and gas pressure are positively correlated under repeated loading and unloading conditions. Relationship between permeability and gas pressure shows that the higher confining pressure, the smaller permeability increasing rate. The calculated equivalent crack apertures are very small at the order of magnitude about 10−8 m. The power law is found to well describe the relationship between equivalent crack aperture and effective stress of natural filled jointed dacite rock. With the parameters determined based on experiment results, an empirical expression is proposed. [ABSTRACT FROM AUTHOR]

A triaxial unloading mechanical test is conducted on sandstone considering different initial confining pressures and unloading rates under the effect of hydraulic coupling. The energy evolution of sandstone unloading failure is studied, and the influences of the initial confining pressure and unloading rate on the deformation characteristics and permeability evolution of sandstone are discussed. It is found that the initial confining pressure and unloading rate have a significant impact on the axial and radial strains of the sandstone, and the radial deformation is more sensitive to the unloading process. The energy dissipation of the sandstone sample increases with the increase of the confining pressure and is nonlinearly correlated to the unloading time. The permeability during the unloading deformation of the sandstone decreases with the increase in the initial confining pressure, indicating that the initial confining pressure of unloading has an inhibitory effect on the permeability of the sandstone. The permeability decreases with the increase in unloading rate, indicating that the faster the increase in the unloading rate, the greater the dissipated instantaneous elastic energy, which is accumulated and released during failure. The higher the degree of fracture in the sample, the larger the peak value of permeability. [ABSTRACT FROM AUTHOR]

Pre-existing joints within a rock mass has a significant effect on the hydro-mechanical properties of the rock mass. The study investigates the hydro-mechanical properties of rock-like materials with intermittent joints under different confining and hydraulic pressures. Cylindrical specimens containing two sets of parallel pre-existing joints were prepared, and the hydro-mechanical experiments under different hydraulic pressures were carried out using a servo-controlled rock triaxial testing system. The test results show that the strength, permeability and deformation properties of the specimens were influenced by the hydraulic pressure. The four stages of evolution of permeability in the deformation process is closely correlated with the development of joints and cracks within the specimen. The relations between volumetric strain and permeability were analyzed and discussed. It is found that the exponential function describes the permeability and volumetric strain relation well in the contraction stage. When the fluid pressure is high, the fluid pressure has a larger impact on the specimen failure mode than the pre-existing thin joints within the specimen in this test. [ABSTRACT FROM AUTHOR]

Spatial variability of properties of geo-materials has a significant impact on the stability of landslides. In this paper, the spatial variability of soil properties of a landslide is modelled using random-field generated by the discrete cosine transform. The method developed can be readily applied to determine the probability of failure of the landslide using Monte Carlo simulation. A case study of a landslide with spatially variable properties is performed and discussed. The proposed approach is shown to be effective and efficient for probabilistic stability analysis of landslides modelled using 2-D random-field. [ABSTRACT FROM AUTHOR]

Uncertainties of geotechnical parameters in landslide engineering mainly arise from their spatial variabilities, measuring error and inaccurate constitutive model. Interval limit equilibrium method (ILEM) is used to analyse the stability of landslides with uncertain geotechnical parameters. However, the method suffers from the issue of overestimation in the calculation of the safety factor (FS) interval while using the basic interval operations. To overcome the limitation, an improved ILEM based on particle swarm optimisation (ILEM-PSO) is proposed in the article. In the method, the uncertain parameters and their intervals are taken as the search variables and search space of PSO, and the FS functions are used as the fitness functions. A predefined number of iterations are executed to search the minimal and maximal FS, which are the lower and upper bound of the FS interval. The proposed method is validated with a testing function and ACADS benchmark question EX11, and then applied to the stability analysis of Dahua landslide. Comparisons with ILEM and Monte Carlo simulation are also given in the article. Results show that the proposed method is effective in solving the issue of overestimation in ILEM and obtains accurate FS intervals of landslides. [ABSTRACT FROM AUTHOR]

Displacement prediction is a direct and effective method for mitigating geohazards. Due to the influence of rainfall and reservoir water level variations, landslides often display step-like deformations with an increasing trend and periodic fluctuation, indicating long-term memory in displacement time series. Traditional data-driven methods are mostly suitable for short-term prediction, and extra data processing is applied to solve this problem. This paper proposes a novel deep learning-based displacement prediction method using long short-term memory (LSTM) networks. Based on open-source frameworks for deep learning, namely, Keras and TensorFlow, a detailed implementation of displacement prediction is proposed and illustrated. The Baishuihe landslide, a typical landslide with long-term monitoring, is taken as a case study, and both single-factor and multi-factor predictions are performed. The results indicate that multi-factor prediction can reduce overfitting and improve accuracy. Compared with the existing method, the multi-factor deep-learning model displays better performance. This study indicates that the LSTM-based deep-learning model is suitable and convenient for displacement prediction and has broad prospects in safety monitoring of water-induced landslides. [ABSTRACT FROM AUTHOR]

The triaxial compression tests under different hydraulic pressures and low confining pressure were carried out to study the hydraulic pressure effect on the mechanical properties and permeabilities of layered rock mass. In general, the results show that the increase of hydraulic pressure reduces the peak strength of layered rock mass and the layer structure changes the mechanical properties of rock mass. With the increase of hydraulic pressure, the peak strength of layered rock mass decreases sharply and then slows down. The peak permeabilities of layered rock mass occurred later than the time when the strength come to the peak. The increase of hydraulic pressure will accelerate the propagation of cracks and significantly enhance the peak permeability of layered rock mass. With the increase of the layer number, the effect of hydraulic pressure becomes more distinct. The initial permeability and the peak permeability increase largely. The increase of hydraulic pressure promotes the expansion and penetration of cracks, so the rock mass develops from tensile failure to the composite failure forms including shear failure and interfacial shear slip failure. [ABSTRACT FROM AUTHOR]

During the reservoir filling of many high arch dams, it was observed that the valley slopes on both sides deformed towards the river. The measured value of valley narrowing lateral deformation (VNLD) reached 89.54 mm by October 2018. This rare phenomenon contradicts the traditional experience of dam engineering and lacks a convincing explanation. An arch dam project in China is selected as a case study to analyze the mechanism of the VNLD. Based on a comprehensive analysis of the geological background and the VNLD measurements, a numerical study is performed to identify the main factors that may contribute to the VNLD phenomenon. It is concluded that the time-dependent valley deformation is due to the rheological behaviour of rock mass with the change of hydrogeological conditions. The artesian water head in the deep-confined aquifer is increased and the mechanical parameters in fault and shear zones are weakened after reservoir filling, which is associated with the specific hydrogeological structures. The rise of artesian water head is the main induced factor that contributes to the uplift deformation, which is observed at the dam site, and can cause the VNLD in the horizontal direction. The simulated results considering these factors agreed well with the observed data. [ABSTRACT FROM AUTHOR]

In order to investigate the hydromechanical behavior of basalt in Baihetan hydropower station in China, a series of uniaxial and triaxial hydromechanical tests were carried out in the laboratory. Experimental results indicated that the deformation state of samples transformed from compaction to dilation. Characteristic stresses were determined by a moving point regression technique, including the crack closure stress σ cc , crack initiation stress σ ci , crack damage stress σ cd , and peak stress σ p , revealing a strong dependence on the confining and pore pressures. Failure modes of the basalt changed from tensile to tensile-shear failure as the confining pressure increased. Moreover, scanning electron microscope (SEM) tests demonstrated that the growth of microcracks caused the failure of the basalt. Based on the experimental results, an elastoplastic constitutive model was proposed to take into account the hardening and softening, as well as the hydro-mechanical behavior of basalt. The return mapping algorithms of the elastoplastic constitutive model are deduced for plastic corrections. Model parameters were determined by experimental results. Finally, the validity of the model was demonstrated by comparing the experimental results with the simulated curves. [ABSTRACT FROM AUTHOR]

Landslide-induced waves often result in severe casualties, economic losses, and even catastrophic consequences, which are far more destructive than the landslide itself. In this paper, accurate geomorphological and geological characteristics of the Wangjiashan landslide in Baihetan Reservoir, southwest China, were obtained through field investigations, and a three-dimensional model was built for numerical calculation. Through the time series curve of cumulative deformation, the water level variation of the reservoir was found to be the major factor causing the landslide deformation and eventual failure. The generation and propagation progress of water waves induced by the Wangjiashan landslide was simulated by coupling the granular flow model and renormalization group turbulence model in FLOW3D. The results show that a large sliding mass silts up the channel, forming a landslide dam with a maximum height of 21.5 m. Nevertheless, it does not block the channel and will not affect standard navigation on account of the wide channel in this area. The maximum run-up wave height of waves spreading to the Xiangbiling resettlement area on the opposite bank is 3.7 m. As the resettlement area is only 1.3 km away from the landslide, and its elevation is only 2.5 m higher than the normal water level of the reservoir, landslide-induced waves should be considered a potential threat. The most vulnerable area affected by landslide-induced waves is about 8 km long along the river, where wave run-up heights are more than 1 m. The results in this paper have important reference values for the early warning and prevention of potential disasters caused by landslides and landslide-induced waves. [ABSTRACT FROM AUTHOR]

Columnar jointed rock masses (CJRMs) have a complex network structure and, therefore, present a great challenge to geotechnical engineering design. A series of triaxial compression tests is performed on artificial CJRM specimens subjected to a confining pressure of 5 MPa, considering various pore pressures (pw=0 MPa , 2 MPa, and 4 MPa). In this work, the influence of the joint dip angles and pore pressure on the anisotropic strength, deformation, and failure modes of the CJRM is investigated. The anisotropic characteristic stresses, strength parameters (c and φ) and elastic modulus of the CJRM specimens show a U-shaped pattern with increasing joint dip angles (β), while Poisson's ratio changes inversely. The elastic modulus has a stronger anisotropy than Poisson's ratio. Moreover, with increasing pore pressure, the characteristic stresses decrease, while the anisotropy of stresses and deformations increases. Finally, three failure modes of CJRM specimens with different joint dip angles are observed under triaxial compression conditions. [ABSTRACT FROM AUTHOR]

Landslide-induced impulse waves in alpine valleys are a significant risk to large-scale dam and reservoir engineering projects in the surrounding area. In this study, a 1 : 200-scale physical model of landslide-induced impulse waves in a V-shaped river channel was established, and 18 groups of tests were conducted to evaluate the influence of different parameters, such as the volume and shape of the landslide body, water entry velocity, and water depth of the reservoir. Based on the test results, a dimensionless formula was established for the first wave height of impulse waves caused by a deep-water landslide in a V-shaped channel. An energy conversion law was determined for the impact of landslide-induced impulse waves on the reservoir bank. Finally, a distribution law was obtained for the initial maximum pressure caused by landslide-induced impulse waves along the water depth on the opposite bank. The theoretical predictions of the dimensionless formula showed good agreement with the experimental results, and the energy conversion rate of the landslide-induced impulse waves initially increased and then decreased with an increasing Froude number. The maximum dynamic water pressure showed a triangular distribution with increasing water depth below the surface of the still water body. The impact pressure of the impulse waves on the slope on the opposite bank increased with the water entry velocity. This study provides a scientific basis for the risk prevention and control of landslide-induced impulse waves in river channels feeding into reservoirs. [ABSTRACT FROM AUTHOR]

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For the tridirectional time histories for seismic analysis, current codes and standards cannot guarantee isotropy in the horizontal directions, the code formula for statistical independence between components is not rigorous, and the bounds are arbitrary. In this paper, three conditions are defined for the horizontal inputs to be isotropic. Orthogonality is proposed to replace the statistical independence for the tridirectional components. Furthermore, the importance of a proper rate of mobilization of the excitation energy of a generated time history is discussed and emphasized, and an acceptance region is proposed for practical applications. [ABSTRACT FROM AUTHOR]

A series of triaxial compression tests under confining pressures of 0, 3, 5, 10, 15 and 20 MPa and lateral extension tests under initial confining pressures of 10, 15 and 20 MPa are conducted. Compared to the test results under loading and unloading conditions, lateral deformation is more sensitive than the axial deformation under unloading process. According to the characteristic of volume strain, the stress–strain curves can be divided into five phases: initial nonlinear compaction, linear elastic, stable crack growth, unstable crack growth and post-peak stage. The experimental results show that dominant failure mode of both tests is shear failure. The failure mode becomes more complex at the confining pressure of 20 MPa in the lateral extension test, consisting of shear and tensile failures. Based on experimental results, a coupled elasto-plastic damage model is proposed using a nonlinear yield function in the p–q plane, using a non-associated plastic potential function in the irreversible thermodynamic framework. The isotropic damage evolution model is formulated with plastic coupling. The numerical simulation results using the coupled model agree well with the experimental data of the fine-grained sandstone, indicating that this model can describe the main mechanical behaviours of the rock under complex loading conditions. [ABSTRACT FROM AUTHOR]

To characterize the cold tolerance mechanism of the Pacific white shrimp (Litopenaeus vannamei), we performed single-cell RNA sequencing (scRNA-seq) of ∼5185 hepatopancreas cells from cold-tolerant (Lv-T) and common (Lv-C) L. vannamei at preferred and low temperatures (28°C and 10°C, respectively). The cells fell into 10 clusters and 4 cell types: embryonic, resorptive, blister-like, and fibrillar. We identified differentially expressed genes between Lv-T and Lv-C, which were mainly associated with the terms "immune system," "cytoskeleton," "antioxidant system," "digestive enzyme," and "detoxification," as well as the pathways "metabolic pathways of oxidative phosphorylation," "metabolism of xenobiotics by cytochrome P450," "chemical carcinogenesis," "drug metabolism-cytochrome P450," and "fatty acid metabolism." Reconstruction of fibrillar cell trajectories showed that, under low temperature stress, hepatopancreas cells had two distinct fates, cell fate 1 and cell fate 2. Cell fate 1 was mainly involved in signal transduction and sensory organ development. Cell fate 2 was mainly involved in metabolic processes. This study preliminarily clarifies the molecular mechanisms underlying cold tolerance in L. vannamei , which will be useful for the breeding of shrimp with greater cold tolerance. [ABSTRACT FROM AUTHOR]

Rainfalls with heavy intensity and long duration are the main factors that trigger landslide. A large-scale test of physical model of landslide induced by gradient rainfall is conducted to investigate the mechanism of landslide caused by rainfalls with an indoor large-scale physical model test system. By monitoring the variation of pore water pressure, soil pressure, slope surface displacement, and groundwater level, the deformation and failure mechanism of deposit landslide under gradient rainfall are studied. The results show that the pore water pressure and soil pressure increase with the increase of the duration of rainfall, and the greater the rainfall intensity is, the greater the peak values of pore water pressure and soil pressure are. The intensity and duration of rainfall are the main influencing factors of landslide deformation. The decrease of effective stress and the rise of groundwater level are the root causes of landslide deformation. During a rainfall, excessive pore water pressure appears in the slope, which can be used as an early warning indicator of landslide deformation and failure. The deformation of slope body is nonlinear and shows a stepped pattern under gradient rainfall. During a rainfall, the toe of the slope is usually damaged first. Tension cracks appear in the rear edge and the middle part of the slope successively, showing the characteristics of traction failure. [ABSTRACT FROM AUTHOR]

Purpose: The objective of this paper is to provide a better understanding of the effect of irregular columnar jointed structure on the permeability and flow characteristics of rock masses. Design/methodology/approach: An efficient numerical procedure is proposed to investigate the permeability and fluid flow in columnar jointed rock masses (CJRMs), of which the columnar jointed networks are generated by a modified constrained centroid Voronoi algorithm according to the field statistical results. The fractures are represented explicitly by using the lower-dimensional zero thickness elements. And the modeling scheme is validated by a benchmark test for flow in fractured porous media. The effective permeability and representative elementary volume (REV) size of CJRMs are estimated using finite element method (FEM). The influences of joint density and variation coefficient of columnar joint structure on the permeability of the rock mass are discussed. Findings: The simulation results indicate that the permeability is scale-dependent and tends to be stable with increase of model size. The hydraulic REV size is determined as 3.5 m for CJRMs in the present study. Moreover, the joint density is a dominant factor affecting the permeability of CJRMs. The average permeability of columnar jointed structures increases linearly with the joint density under the same REV size, while the influence from the coefficient of variation can be neglected. Originality/value: The present paper investigates the REV size of the CJRMs and the effect of joint parameters on the permeability. The proposed method and the results obtained are useful on understanding the hydraulic characteristic of the irregular CJRMs in engineering projects. [ABSTRACT FROM AUTHOR]

This paper presents an experimental study on the mechanical behavior and permeability evolution of basalt, drilled from the dam foundation of the Baihetan Hydropower Station in China. Two groups of triaxial unloading creep tests under hydro-mechanical coupling conditions were conducted. Based on the experimental results, creep deformation and failure characteristics of basalt were investigated. It was found that the relationship between the confining pressure and steady creep rate could be described satisfactorily by an exponential function. A tensile-shear failure mode was observed for basalt under the action of unloading confining pressure and hydraulic-mechanical coupling. The permeability evolution of basalt in the unloading creep process exhibited phased characteristics: permeability decreased in the initial loading phase and remained stable for a certain range of confining pressure in the steady creep phase. Exponential functions were also used to describe the evolution of permeability and confining pressure. The results of this study can provide a comprehensive understanding for the long-term stability assessment of basalt under coupled hydro-mechanical conditions. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to analyze the influence of rotated anisotropy on the stability of slope, the random finite element method is used in this study. Design/methodology/approach: The random field is generated by the discrete cosine transform (DCT) method, which can generate random field with different rotated angles conveniently. Findings: Two idealized slopes are analyzed; it is observed that the rotated angle significantly affects the slope failure risk. The two examples support the conclusion that when the orientation of the layers is nearly perpendicular to the slip surface, the slope is in a relative stable condition. The results of heterogeneous slope with two clay layers demonstrate that the rotated angle of lower layer mainly controls the failure mechanism of the slope, and the rotated angle of upper layer exhibits a significant influence on the probability of slope failure. Originality/value: The method for rotated anisotropy random field generation based on the DCT has a simple expression with few parameters and is convenient for implementation and practical application. The proposed method and the results obtained are useful for analyzing the stability of the heterogeneous slopes in engineering projects. [ABSTRACT FROM AUTHOR]

Background: As non-coding RNA molecules of more than 200 bp in length, long non-coding RNAs (lncRNAs) play a variety of roles in biological processes, including regulating the immune responses to bacterial infections. In recent years, there have been many in-depth studies on mammalian lncRNAs, but the relevant studies in fish are very limited. Meanwhile, since lncRNAs are not conserved among species, it is difficult to apply the existing results directly to unstudied species. Results: To obtain the information of lncRNAs in Megalobrama amblycephala, one of the most economically important freshwater fish in China, also to better understand the biological significance of lncRNAs in the immunity system, the fish liver at 0, 4, 12, 24, and 72 h post Aeromonas hydrophila infection (hpi) were obtained for lncRNA-sequencing (lncRNA-seq). A total of 14,849 lncRNAs were identified, and 2196 lncRNAs showed significant differences at different time points post A. hydrophila infection. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed that the target genes of the differentially expressed lncRNAs were enriched in several pathways related to immune such as apoptosis, inflammation, and immune response. Time-specific modules were then identified, using weighted correlation network analysis (WGCNA), and 28 modules significantly correlated with different time point after infection were found. Furthermore, four immune-related genes and six lncRNAs in the time-specific modules were subsequently verified by RT-qPCR. Conclusions: The above findings reveal the discovery of widespread differentially expressed lncRNAs in the M. amblycephala liver post A. hydrophila infection, suggesting that lncRNAs might participate in the regulation of host response to bacterial infection, enriching the information of lncRNAs in teleost and providing a resources basis for further studies on the immune function of lncRNAs. [ABSTRACT FROM AUTHOR]

The influence of three-dimensional (3D) rotated anisotropy on the stability of soil slope is investigated. Random field theory is employed to model the heterogeneity of soil shear strength parameters, and finite element analysis is conducted to compute the slope response. In addition, Monte Carlo simulations are carried out to compute the probability of the 3D slope failure. Based on the simulation results of an idealized 3D soil slope, it is observed that the rotated angle significantly affects the slope failure probability as well as the failure mechanism. [ABSTRACT FROM AUTHOR]

To explore genetic diversity and estimate the genetic differences among populations of Lutraria maxima in the coastal waters off south to southeast China, the morphology of the species of five different geographical populations (Beihai, Weizhou Island, Zhanjiang, Xiamen, and Fuzhou) in Guangxi, Guangdong, and Fujian provinces was studied statistically in combination with the microsatellite markers. As revealed by morphological principal component analysis (PCA), the cumulative contribution rate of the first three principal components was 72.596%. The discrimination accuracy ranged from 47.5% to 80.0%, and the scatter plots of principal component and discriminant analysis were consistent in overall, showing that the Xiamen and Fuzhou populations were overlapped obviously. For microsatellite markers, 10 pairs of polymorphic primers were obtained by high-throughput transcriptome sequencing, and used for genetic diversity analysis. It was showed that the average number of alleles and effective alleles observed in each population ranged from 8.100 to 10.900, and from 3.497 to 4.228, respectively. The average observed heterozygosity (Ho) and expected heterozygosity (He) in the five populations ranged from 0.541 to 0.615, and from 0.642 to 0.733, respectively. The genetic distance (DA) ranged from 0.078 to 0.523, and the population genetic differentiation index (FST) ranged from 0.027 to 0.139. The unweighted pair-population method with arithmetic means (UPGMA) and structure analysis showed that the five populations could be divided into two main clusters, the Beibu Gulf group (Beihai and Weizhou Island) and the Southeast China Sea group (Zhanjiang, Xiamen, and Fuzhou), suggesting that L. maxima has been separated geographically by the barrier of the Leizhou Peninsula into two groups in evolution, which provided us with a scientific clue to better protect the bioresource and establish an appropriate fishery management stocks for L. maxima populations in south China. [ABSTRACT FROM AUTHOR]

Located in reservoir area of Dahuaqiao Hydropower Station in Lancang River, the Dahua ancient deposit landslide exhibits high possibility of reactivation due to reservoir impoundment. In this study, physical model tests are conducted to investigate the variations of groundwater, deformation, and failure process of the landslide under different fluctuation speeds of reservoir water level. Influence of groundwater on landslide stability when reservoir water level fluctuating is analyzed then. Results indicate that the seepage pressure caused by water level difference can increase landslide displacement. During the dropping process of reservoir water level, the relationship between landslide displacement and water level difference can be described by a power function model. Groundwater has negative effects on stability of landslides, and the damage is characterized by traction landslide. More attentions should be paid on the displacement of the front edge of the landslide during the first rise and drop of reservoir water level. The study provides indispensable information for scheduling reservoir water level in the Dahuaqiao and others similar reservoir areas, thus having vital importance. [ABSTRACT FROM AUTHOR]

In this paper, a series of experiments were conducted on typical volcanic breccia collected from the foundation of Baihetan Dam. Considering previous work, the mechanical behavior and permeability of the volcanic breccia were further investigated. The experimental results showed that the compressive strength and Young's modulus of the volcanic breccia decrease due to the presence of water. However, the Poisson's ratio of the wet specimens was higher than that of the dried specimens. The permeability evolution under triaxial compression was divided into 5 stages. The fluid pressure showed a great influence on the permeability of the volcanic breccia. The water weakening mechanism and the effect of fluid pressure on the permeability were discussed. The effect of water on the strength of volcanic breccia is influenced by both subcritical crack growth and calcite dissolution. Due to the pore pressure gradient and the water weakening effect, the change in permeability with volumetric strain varies greatly. [ABSTRACT FROM AUTHOR]

Rock mass classification is important in preliminary design of geotechnical engineering projects. Using the columnar jointed basalt at the foundation of Baihetan Hydropower Station as an example, this paper presents a classification scheme of the columnar jointed rock. Unlike many common rock masses, an obvious characteristic of columnar jointed rock is that it is discontinuous in geometry while continuous in mechanics. Due to the inapplicability of existing rock mass classification systems, a classification scheme, combined with rock mass integrity, weak plane tightness, and permeability, is proposed. The new classification system has five grades with quantitative factors, which takes into account the features of columnar joints. As an easy-to-use scheme and case study, it would be helpful as a reference in the rock mass classification of similar problems. [ABSTRACT FROM AUTHOR]

Columnar jointed rock masses (CJRM), characterized by regular arrays of polygonal prisms or columns, are exposed in the dam foundation of the Baihetan hydropower station and pose a challenge to the stability of the project. To understand the hydro-mechanical behaviour of Baihetan CJRM, triaxial compression experiments are carried out on artificial CJRM specimens with regular arrays of hexagonal columns, which are similar to the actual CJRM. Based on the experimental results, mechanical and hydraulic behaviour of CJRM is studied. It is found that the compressive strength of CJRM varies in a typical U-shape with the joint inclination angle. Three failure modes associated with the angle of joint inclination are observed. The evolution of permeability with stress exhibits distinct phased characteristics: initial compression stage, linear elastic stage, yield stage, and strain-softening stage. The results of this study provide helpful information for the design and construction of the Baihetan project involving CJRM. [ABSTRACT FROM AUTHOR]

Soil-rock mixture is a widely distributed geological material in mountainous regions, where slope stability is an important issue. To investigate the influence of rock on slope stability, firstly, rocks in SRM are generated and then SRM slope models are simulated based on the finite difference method (FDM). The impact of various characteristics of rocks on slope factor of safety (FOS) is studied systematically by using the reduced strength method. The characteristic of rock considered include rock content, number of rock edges, aspect ratio, rock size and inclination of rock. The simulations indicate that increasing the rock content can prevent the development of high strain region and improve slope stability. However, the aspect ratio of rock has negligible impact on the mean value of FOS. For slopes with 45° slope angle, rocks with 45° angle of inclination result in smooth potential sliding surface, whereas rocks with 135° angle of inclination lead to more tortuous potential sliding surfaces. Statistical indices are utilized to analyze the results of numerical modelling. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper is to investigate the mechanical behavior and propagation of cracks of numerical granite samples through the Brazilian split test and to provide a reference for predicting the behavior of real granite samples. Design/methodology/approach: The numerical models of granite containing two fissures are established using the parallel bond model (PBM) and the smooth joint model (SJM) in PFC2D. The peak stresses, number of cracks and anisotropic ratios are obtained to study the influence of the mineral composition and the angle of inclination of rock bridge on the strength, failure mode and deformation characteristics. Findings: The numerical results obtained show that the mineral composition has a marginal influence on the peak stress. When the angle of inclination of rock bridge β increases, the peak stress drops to its minimum value at β = 90° and then gradually increases to a relatively low level. The behavior of cracks falls into three categories based on the distribution of cracks. By analyzing the stress–strain curve and the process of crack propagation for sample No. 4 with β = 60°, it is found that the process of failure can be divided into four stages and tensile cracks dominate. The anisotropic ratios of peak stress and a number of cracks obtained show that the peak stress is low anisotropic and the number of cracks is medium anisotropic. Originality/value: This paper presents a numerical simulation method to analyze mechanical behavior and propagation of cracks under different conditions. The proposed method and the results obtained are useful for predicting the behavior of real granite samples in laboratory and engineering projects. [ABSTRACT FROM AUTHOR]

The objective of this study is to provide an effective method for risk prediction and disaster control of earthquake-induced landslides. The Hongshiyan landslide induced by Ludian earthquake (Mw6.5) on August 3, 2014, in Ludian County, Yunnan Province, China, is studied. The sliding process and the mechanism of instability are investigated through numerical simulations using the particle flow codes (PFC). The characteristics of velocity and displacement and features of deposit are studied. It is found that the maximum average velocity of all particles of 23.43 m/s occurs at 7.11 s. The maximum displacement is closely related to elevation, and the sliding time of the rear edge of the sliding body is the longest. The numerical results of the landslide dam deposit morphology, with a height of 116.1 m and a length of 1001.1 m, are in good agreement with the field investigations. A series of numerical experiments on parameter sensitivity are also performed to study the influence of amplification factor and coefficient of friction on the features of the deposit. [ABSTRACT FROM AUTHOR]

Nitrite is a major environmental toxin in aquaculture systems that disrupts multiple physiological functions in aquatic animals. Although nitrite tolerance in shrimp is closely related to successful industrial production, few genetic studies of this trait are available. In this study, we constructed a high-density genetic map of Litopenaeus vannamei with 17,242 single nucleotide polymorphism markers spanning 6,828.06 centimorgans (cM), with an average distance of 0.4 cM between adjacent markers on 44 linkage groups (LGs). Using this genetic map, we identified two markers associated with nitrite tolerance. We then sequenced the transcriptomes of the most nitrite-tolerant and nitrite-sensitive individuals from each of four genetically distinct L. vannamei families (LV-I–4). We found 2,002, 1,983, 1,954, and 1,867 differentially expressed genes in families LV-1, LV-2, LV-3, and LV-4, respectively. By integrating QTL and transcriptomics analyses, we identified a candidate gene associated with nitrite tolerance. This gene was annotated as solute carrier family 26 member 6 (SLC26A6). RNA interference (RNAi) analysis demonstrated that SLC26A6 was critical for nitrite tolerance in L. vannamei. The present study increases our understanding of the molecular mechanisms underlying nitrite tolerance in shrimp and provides a basis for molecular-marker-assisted shrimp breeding. [ABSTRACT FROM AUTHOR]

The permeability of sandstone during hydrostatic compaction and triaxial deformation was measured using a rock triaxial servo-controlled system. The gas permeability was also measured using an integrated permeability and porosity test system to study the difference between gas and water permeability. The experimental results suggested that gas permeability is larger than water permeability by almost one order of magnitude. This phenomenon is due to the slippage effect. The modified permeability is much closer to the water permeability. An empirical exponential relationship can describe the stress-dependent permeability of sandstone, while a power law is suitable to describe the relationship between porosity and effective confining pressure. During triaxial deformation, permeability initially decreases and then begins to increase at an accelerating rate. The peak value of permeability is hysteretic to peak stress. The initial permeability, lowest permeability, peak permeability, and stable value of permeability all decrease with the increase of effective confining pressure. The volumetric strain has a great effect on permeability. The turning point where permeability starts to increase coincides well with the onset of dilatancy. [ABSTRACT FROM AUTHOR]

Rainfall, groundwater, and fluctuation in reservoir levels are considered among the main external factors affecting the stability of slopes. The impact of groundwater is particularly evident during the rainy season. In this paper, a case study on a geological investigation of the Donglingxing (DLX) landslide is presented to demonstrate a drainage control strategy. Due to the characteristics of the landslide and the limitations on the construction of stabilizing piles, a drainage tunnel system is herein used to reduce the risk of landslide. A comprehensive analysis is conducted on the monitoring data of rainfall, groundwater levels, reservoir water level, and drainage discharges from the tunnels. Based on field measurement data on groundwater level, water discharge, and deformation of the landslide before and after construction of the drainage tunnel, the effectiveness of the drainage tunnel system is evaluated. The results indicate that the drainage tunnel is effective in increasing the stability of landslide, and this work can serve as a reference case for other landslides. [ABSTRACT FROM AUTHOR]