In mountainous areas, channelized rock avalanches swarm downslope leading to large impact forces on building structures in residential areas. Arrays of rock avalanche baffles are usually installed in ...front of rigid barriers to attenuate the flow energy of rock avalanches. However, previous studies have not sufficiently addressed the mechanisms of interaction between the rock avalanches and baffles. In addition, empirical design approaches such as debris flow (Tang et al., Quat Int 250:63–73,
2012
), rockfall (Spang and Rautenstrauch, 1237–1243,
1988
), snow avalanches (Favier et al., 14:3–15,
2012
), and rock avalanches (Manzella and Labiouse, Landslides 10:23–36,
2013
), which are applied in natural geo-disasters mitigation cannot met construction requirements. This study presents details of numerical modeling using the discrete element method (DEM) to investigate the effect of the configuration of baffles (number and spacing of baffle columns and rows) on the impact force that rock avalanches exert on baffles. The numerical modeling is firstly conducted to provide insights into the flow interaction between rock avalanches and an array of baffles. Then, a modeling analysis is made to investigate the change pattern of the impact force with respect to baffle configurations. The results demonstrate that three crucial influencing factors (baffle row numbers, baffle column spacing, and baffle row spacing) have close relationship with energy dissipation of baffles. Interestingly, it is found that capacity of energy dissipation of baffles increases with increasing baffle row numbers and baffle row spacing, while it decreases with increasing baffle column spacing. The results obtained from this study are useful for facilitating design of baffles against rock avalanches.
A dump is a loose accumulation of solid waste from mining operations that easily leads to disasters such as landslides and debris flows. Taking a dump in the Panzhihua region of China as an example, ...based on the MPM and SPH meshless methods, the dynamic calculation of the instability process of the spoil slope was carried out according to the realistic three-dimensional calculation model of the generated terrain. Firstly, the strain and displacement of the dump under normal conditions and heavy rainfall conditions were simulated by the MPM material point method. The maximum spatial displacement of the dump under heavy rainfall conditions reached up to 386 m. Then, the motion and morphology of the accumulation of the dump under ordinary working conditions and heavy rainfall conditions were analyzed using the smooth particle hydrodynamics (SPH) method. Under heavy rainfall conditions, the maximum horizontal displacement of the dump was approximately 394 m. The research results are conducive to the risk assessment of the spoil slope and provide theoretical support for the calculation of the range of potential threats from the dump.
The present study aimed to remove crystal violet (CV), malachite green (MG), Cd(II), and Pb(II) from an aqueous solution using clinoptilolite zeolite (CZ) as an adsorbent. Response surface ...methodology (RSM) based on central composite design (CCD) was used to analyze and optimize the process parameters, such as pH, analyte concentration, adsorbent amount, and sonication time. Quadratic models with the coefficient of determination (R
2
) of 0.99 (
p
< 0.0001) were compared statistically. The results revealed that the selected models have good precision and a good agreement between the predicted and experimental data. The maximum removal of contaminants was achieved under optimum conditions of pH = 6, sonication time of 22 min, the adsorbent amount of 0.19 g, and analyte concentration of 10 mg L
−1
. The reusability test of the adsorbent showed that the CZ adsorbent could be used 5 times in water and wastewater treatment processes. According to the results of interference studies, the presence of different ions, even at high concentrations, does not interfere with the removal of contaminants. Applying the CZ adsorbent on environmental water samples revealed that CZ adsorbent could remove CV, MG, Cd(II), and Pb(II) in the range of 84.54% to 99.38% and contaminants present in industrial effluents. As a result, the optimized method in this study can be widely used with high efficiency for removing CV, MG, Cd(II), and Pb(II) from water and wastewater samples.
Limestone calcined clay cement (LC3) is an environment-friendly and sustainable cementitious material. It has recently gained considerable attention for the stabilization/solidification (S/S) of ...soils contaminated by heavy metals. However, the existing studies on S/S of Zn-contaminated soils using LC3 in terms of hydraulic conductivity and microstructural properties as compared to ordinary Portland cement (OPC) are limited. This study focuses on the evaluation of the mechanical, leaching, and microstructural characteristics of Zn-contaminated soils treated with different contents (0%, 4%, 6%, 8%, and 10%) of low-carbon LC3. The engineering performance of the treated Zn-contaminated soils is assessed over time using unconfined compressive strength (UCS), hydraulic conductivity (
k
), toxicity characteristic leaching procedure (TCLP), and synthetic precipitation leaching procedure (SPLP) tests. Experimental results show that the UCS of Zn-contaminated soils treated with LC3 ranged from 1.47 to 2.49 MPa, which is higher than 1.63%–13.07% for those treated with OPC. The
k
of Zn-contaminated soils treated with LC3 ranged from 1.16×10
−8
to 5.18×10
−8
cm/s as compared to the OPC treated samples. For the leaching properties, the leached Zn from TCLP and SPLP is 1.58–321.10 mg/L and 0.52–284.65 mg/L as the LC3 contents ranged from 4% to 10%. Further, the corresponding pH modeling results indicate that LC3 promotes a relatively suitable dynamic equilibrium condition to immobilize the higher-level Zn contamination. In addition, microscopic analyses demonstrate that the formations of hydration products, i.e., Zn(OH)
2
, Zn
2
SiO
4
, calcium silicate hydrate (C–S–H), calcium silicate aluminate hydrate (C–A–S–H) gel, ettringite, and CaZn(SiO
4
)(H
2
O), are the primary mechanisms for the immobilization of Zn. This study also provides an empirical formula between the UCS and
k
to support the application of LC3-solidified Zn-contaminated soils in practical engineering in the field.
In order to study the thermodynamic effects of highway construction in plateau areas on frozen soil corridors, starting from the current practice of the frozen soil disease remediation project in ...plateau areas from 2017 to 2019, the mechanism of highway disease occurrence was discussed. The analysis was carried out, and the frozen soil was treated by the simulation test method. The field tests were conducted to investigate the actual use of the thermal insulation board subgrade and gravel subgrade of the diseased section. The temperature field distribution law of the frozen soil corridor project under periodic fluctuation of the boundary temperature was explored. The representative road section observation data was adopted to predict the temperature variation. Thermal characteristics of permafrost engineering corridors were analyzed. Taking the Golmud-Lhasa highway as the research object, the research results show that the construction method of the highway through the plateau directly affects the thermodynamic characteristics of the permafrost corridor project. Effective strategies have been obtained to control temperature changes, reduce roadbed damage, and enhance the thermal characteristics of permafrost engineering corridors.
Accurate prediction of the scour hole depth and dimensions downstream of ski-jump spillways has been an important issue among hydraulic researchers for decades. In recent years, computing methods ...such as Artificial Neural Networks (ANNs), Adaptive Neuro-Fuzzy Inference Systems (ANFISs) and Support Vector Regression (SVR) have shown a powerful performance in the prediction of scour characteristics owing to their flexibility and learning nature. In the present paper, a new hybrid approach has been proposed for the first time in order to improve the estimation power of the SVR tool for scour hole geometry prediction below ski-jump spillways. The principal characteristics of the scour hole pattern in the equilibrium phase have been predicted using SVR optimized with Fruitfly Optimization Algorithms (FOAs). The hybrid model is compared with the corresponding simple SVR model. To evaluate the proposed hybrid model further, it is also compared with other machine learning and empirical methods, such as ANNs, ANFISs and regression equations. The results show that the proposed SVR-FOA method performs well, improves remarkably on Support Vector Machines (SVMs) results, estimates scour hole geometrical parameters more accurately than the simple SVR model, and can be applied as an alternative reliable scheme for estimations on which simple SVR and other methods demonstrate shortcomings. The proposed hybrid method improves the precision level for scour depth prediction by about 8% compared with simple SVM in terms of the correlation coefficient.
In this paper, a discussion is presented about the impact-induced damage suffered by bridge pier columns during rockfall events through model tests and impact force, column top displacement, ...stress-strain response, and other parameters in relation to the process of impact. On this basis, the following conclusions are drawn. Firstly, the impact force, as well as the displacement and strain of the column top, increases rapidly after taking a hit, while the displacement is reduced after reaching its maximum. Secondly, at the same falling height, the higher the impact position, the smaller the peak of impact force and the longer the attenuation period. Thirdly, at the same impact height, the impact energy, the displacement of the column top, and the peak of the impact force increase as the falling height of the pendulum ball is on the rise, but the attenuation period remains unchanged. Fourthly, the failure mode of column impacted by the swing ball conforms to shear-flexural failure. Fifthly, it is recommended to strengthen the preventative measures for those weak positions like 1/2 height and 1/4 height of bridge pier, so as to minimize the potential damage caused by rockfalls. Besides, a theoretical formula used to estimate the maximum impact force is proposed. Lastly, under the axial load of bridge deck, the performance of the pier in impact resistance under rockfall is better and the damage is less severe than in the experimental impact test. The axial load applied by the deck imposes some constraints on the pier, thus reducing concrete damage. The research results can contribute to the research on addressing the rockfall-bridge pier collision problem. The experimental research demonstrates its theoretical significance to engineering for the prevention of rockfall.
•Novel ELM and GTB models are used for estimating brine/CO2/mineral contact angles.•Accuracy of models are proved for simulation of CO2/brine wettability on minerals.•Outlier detection and ...sensitivity analyses are used for further investigation.
•A proposed finite element model could reproduce the experimental results.•Numerical simulation verifies the failure mode of large-diameter anchor.•Progressive failure of anchor can be parsed in four ...stages based on load–displacement curve.
Large-diameter anchors are one of the important connection components in the reinforcement of industrial facilities. In the present study, a finite element (FE) model of large-diameter post-installed anchor system is appropriately established to investigate its pull-out performance and failure modes observed in the prototype experiments. The applicability of the proposed model is discussed through comparison of its results with experimental results (e.g., in terms of the ultimate load, corresponding displacement, and failure modes), and the parametric sensitivity based on the numerical results is studied. The results showed that the pull-out behavior could be well simulated using the proposed model. The progressive failure evolution process of the large-diameter anchor can be revealed by computational load–displacement curves. Thus, the proposed model of a large-diameter post-installed anchor can enable reliable design of anchor systems for industrial reinforcements.
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