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In this work, sustainable cement clinkers and ecofriendly cementitious materials (ECMs) were prepared with iron ore tailings (IOTs). Alternative raw meals with IOTs were sintered to cement clinkers by conventional sintering processes. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM) and mechanical tests suggested that the cement clinker within 10 wt% IOTs had better quality than those without IOTs. In addition, the hydration and hydration products of the IOT-based cement were analyzed via XRD and SEM. Before preparing ECMs, IOTs were pretreated with a 100 mesh Tyler screen to remove silt and clay. Then, the pretreated IOTs and whole IOTs partly instead of fine aggregates, together with IOT-based cement were used to produce ECMs. The ratio of water-binder and compressive strength properties of the ECMs were investigated. It is suggested that the pretreated IOTs sand can be used as much as 60 wt%, while the amount of whole IOTs sand must be limited to 20 wt% before the performance dramatically decrease. These findings suggest that disposal of a high volume of Yeshan IOTs in sustainable construction building materials has feasibility and operational significance.

The investigation of the blasting effects of the borehole considering decoupled eccentric charge is scarce and lacks thorough exploration. The coupled Smoothed Particle Hydrodynamics and Finite Element Method (SPH-FEM) is adopted to study the decoupled eccentric charge blasting effects. The effective stress distribution of rock around the borehole is analyzed and the damage evolution is studied quantitatively with introducing image recognition algorithm. Further, the effect of the decoupling coefficient on blasting effects is investigated. Results show that effective stress distribution presents obvious eccentric characteristics. At the bottom coupling point, the maximum effective stress is observed, and gradually reduces towards the top uncoupling point. The lower part of rock surrounding the borehole exhibits a higher damaged area ratio compared to the upper part for decoupled eccentric charge blasting. With the decoupling coefficient increases from 1.14 to 2.00, the effective stresses at monitoring points are all decreasing and the effective stress ratio first increases and then keeps relatively stable, with the decoupling coefficient of 1.6 as inflection point. As the decoupling coefficient increases to 1.6, the damage extent ratio reaches the peak. The greatest disparity in explosion energy between the coupled and uncoupled sides occurs at a decoupling coefficient of approximately 1.6.

Prioritizing multiple potentially unstable slopes based on varying levels of criticality is an essential approach when resources are limited. This study presents a framework for planning the prioritization of unstable rock slope remediation. The prioritization of mitigation measures for these slopes is determined using deformation values derived from indirect information, such as rock classification systems. To demonstrate the application of this framework, a case study involving unstable rock slopes in southwestern China is presented. Initially, the most appropriate estimation model was chosen from among six candidates for estimating the deformation modulus of the unstable rock mass in the slope, utilizing indirect information. Subsequently, the deformation modulus, updated through Bayesian analysis, was employed to generate the corresponding deformation distributions for the rock slopes. Compared to traditional quantitative methods, the proposed framework is adaptable to various working conditions and yields more definitive results. The indirect data used in this framework are cost-effective, enabling the assessment of all unstable slopes. Moreover, the effect of the amount of indirect data and prior information on slope remediation prioritization is discussed. The proposed framework offers a valuable tool for decision-makers in planning and prioritizing mitigation measures.

Aluminum nanoparticles (nAl) have received sustained interest due to their higher reactivity than micron aluminum particles (mAl). However, in practice, the densities of explosive formulations with nAl are far smaller than those with mAl, which greatly undercuts the energy release performance. To take advantages of both kinds of Al particles, in situ integration of mAl@nAl composites was proposed and evaluated. The mAl@nAl composites were prepared by in situ electrical explosion of Al wire. Their morphology, density, and specific surface area (SSA) were characterized by scanning electron microscope (SEM), densimetry, and Brunauer–Emmett–Teller (BET), respectively. SEM showed that nAl uniformly adhered to the surface of mAl. With the increase in voltage, the average diameter and density of the composites decreased, but the SSA of the composites increased. And the largest density of the composites was 1.13 g/cm3, comparable to that of the commercial graded Al product (1.25 g/cm3). Meanwhile, the highest SSA of the composites was 12.1192 m2/g. In addition, the combustion efficiency of mAl@nAl composites at 20 kV was 8.26% higher than that of physically graded counterparts. The constant-volume combustion test under zero oxygen balance revealed that the pressurization rate and peak pressure of mAl@nAl composites prepared at 20 kV were the highest of all. Furthermore, constant-volume combustion under constant heat showed that the combustion temperatures of mAl@nAl composites were 1.15–1.45 times higher than those of physically graded counterparts. Finally, the ignition delay of mAl@nAl composites was reduced with the increase in explosion voltage.

Shale is composed of a rock matrix and bedding planes with a layered structure, resulting in significant anisotropy in its mechanical properties. In order to study the anisotropic mechanical properties of shale, the shale samples were prepared in different orientations with respect to the bedding planes, and the composition and microstructure of shale were first analyzed by X-ray diffractometer (XRD) and scanning electron microscope (SEM), and then the uniaxial and triaxial compression experiment on shale samples with five different bedding angles (the angle between the loading direction and the normal direction of the bedding planes, 0°, 30°, 45°, 60°, and 90°) were conducted under five confining pressures (0, 10, 20, 30, and 40 MPa), respectively; meanwhile, the acoustic emission (AE) test was carried out in the uniaxial test. The results indicate that the mechanical properties and parameters of shale have obvious anisotropy, and the AE characteristics of shale samples with different bedding angles are significantly different during uniaxial loading. Furthermore, the compressive strength and elastic modulus of the shale samples first decrease and then increase with the increase in the bedding angle under different confining pressures. Moreover, according to the anisotropic grade of compressive strength, the shale has moderate anisotropy. In addition, the failure mode of the shale samples is also anisotropic, and varies with the bedding angle and confining pressure.

Unexpected ground impacts can seriously affect the stability and operational safety of buried pipelines. In this paper, a full-scale modeling test of the dynamic response of a buried concrete pipeline under falling rock impact based on dynamic sensor testing was conducted. A commercially available reinforced concrete pipeline, buried in a clayey soil site, was used, and a 50 kg concrete ball was used to investigate the impact above the pipeline. Considering the purpose of the test, the falling process of the concrete ball and the surface vibration velocity induced by the touchdown of the concrete ball were monitored using a high-speed camera and a vibration signal tester, respectively. The dynamic response signals of the pipe under surface impact were tested using strain gauges and earth pressure gauges combined with dynamic sensors such as dynamic signal tester, and the dynamic response law was analyzed. The experimental results will provide a basis for the design of the impact resistance of reinforced concrete pipes.

The road transportation of explosives is highly concerning due to its substantial impact on social safety. For the safety management of explosive transportation, e.g., transport route planning and emergency rescue, explosion consequence evaluation is of paramount importance. The consequence evaluation of explosion accidents is affected by many factors, especially spatial features, such as the location of transport vehicles, the distribution of buildings, and the presence of individuals around the road, etc. However, there is still a lack of quantification methods for building damage evaluation, human casualty evaluation that considers real-time population density, and efficient interactive damage evaluation methods. In this paper, we formalize three typical scenarios of damage evaluation for explosive road transportation accidents, i.e., explosion point-based, road segment-based, and route-based damage evaluation. For each scenario, we propose a Height-aware Hierarchical Building Damage (HHBD) model and a Shelter-aware Human Casualty (SHC) model for building damage evaluation and human casualty evaluation, respectively. We also develop a GIS-based interactive visualization platform that integrates multi-source geospatial data and that enables efficient geospatial computation. In addition, a case study of liquefied natural gas (LNG) transportation in Wuhan is demonstrated in order to verify the effectiveness and efficiency of the proposed system. The research results can support the decision-making process of explosive transportation safety warnings and emergency rescue.

Blast stress waves profoundly impact engineering structures, exciting and affecting the rupture process in brittle construction materials. A novel numerical model was introduced to investigate the initiation and propagation of cracks subjected to blast stress waves within the borehole-crack configuration. Twelve models were established with different crack lengths to simulate sandstone samples. The influence of crack length on crack initiation and propagation was investigated using those models. The linear equation of state was used to express the relationship between the pressure and density of the material. The major principal stress failure criterion was used to evaluate the failure of elements. A triangular pressure curve was adopted to produce the blast stress wave. The results indicated that the pre-crack length critically influenced the crack initiation and propagation mechanism by analyzing the stress history at the crack tip, crack propagation velocity, and distance. The inducement of a P-wave and S-wave is paramount in models with a short pre-crack. For long pre-crack models, Rayleigh waves significantly contribute to crack propagation.

Seismic waves induced by blasting can cause damage to slope rock masses and thus lower the stability of the slope. The vibration standards of many countries do not specify the allowable blasting vibration velocity for slope rock masses. “Blasting Safety Regulations” (GB 6722-2014) in China recommends the allowable blasting vibration velocity of slope rock masses. However, the strength of rock mass and geometric characteristics of slope are not considered in the criterion. Therefore, based on the wave equation of Rayleigh wave, the mathematical relationship between the additional dynamic stress of the rock mass near the slope surface and the peak particle velocity (PPV) on the ground is analyzed. Under the control conditions that no tensile and shear damage occur in the slope, a calculation method of allowable blasting vibration based on a simple slope model is proposed, in which the strength of rock mass and the angle of the slope are considered. The theoretical basis of the proposed method is verified by numerical experiments. Based on the field test results of the slope of Xiaowan Hydropower Station, the proposed method was verified further. The damage control target of the rock mass determined by the proposed method was in good agreement with the actual damage detection result.

Aiming at the problem of displacement of collapse direction caused by the impact of the high-rise reinforced concrete chimney in the process of blasting demolition, combined with the monitoring methods such as high-speed photography observation, piezoelectric ceramic sensor, and blasting vibration monitor, the impact process of the 180 m high chimney was comprehensively analyzed. The results show that the chimney will experience multiple ‘weight loss’ and ‘overweight’ effects during the sit-down process, inducing compressive stress waves in the chimney. When the sit-down displacement is large, the broken reinforced concrete at the bottom can play a significant buffering effect, and the ‘overweight’ effect gradually weakens until the sit-down stops. The stress of the inner and outer sides of the chimney wall is obviously different in the process of collapsing and touching the ground. The waveform of the monitoring point of the piezoelectric ceramic sensor is divided into three stages, which specifically characterizes the evolution process of the explosion load and the impact of the chimney. The vibration induced by explosive explosion is mainly high-frequency vibration above 50 Hz, the vibration induced by chimney collapse is mainly low-frequency vibration below 10 Hz, and the vibration characteristics are obviously different. In the process of blasting demolition and collapse of high-rise reinforced concrete chimney, due to the impact of sitting down, the wall of the support tube is subjected to uneven force, resulting in the deviation of the collapse direction. In practical engineering, the control measures of chimney impact, blasting vibration, and collapse touchdown vibration should be fully strengthened to ensure the safety of the protection target around the blasting demolition object.

The dynamic response of twin circular unlined tunnels is studied by indirect boundary integral equation method (IBIEM). The twin tunnels are assumed to lie in an unbounded elastic space subjected to blasting P waves. The influence of incident angle on the distribution of DSCF around the twin tunnels is analyzed. Besides, the influences of normalized wave number αa and normalized distance d* (ratio of spacing distance to tunnel radius) on the reference DSCF, that is, the peak DSCF for different incident angles with an assurance rate of 95%, are discussed. Results show that 1) the IBIEM is a high-precision method analyzing the DSCF around twin circular unlined tunnels induced by blasting P waves; 2) the incident angle θ0, αa, and d* all have significant influences on the distribution of DSCF; 3) for a constant d*, the peak DSCF around the right tunnel is slightly greater than the left one; 4) the reference DSCF decreases exponentially with the increasing of αa or d*, and the corresponding fitting functions are proposed.

During blasting excavation in deep rock masses, the in situ stress initially exerted on blast-created free surfaces is rapidly released along with rock cracking by blasting. The rapid stress release can initiate seismic waves transmitting through the medium. In addition to explosion loading, the rapid stress release occurring on blast-created free surfaces is another excitation source of the rock vibration generated in blasting excavation of deep rock masses. In this paper, a theoretical model of seismic wave radiation from a circular blasting excavation in a deep rock mass is first developed to study the frequency differences between explosion seismic waves and stress release-induced seismic waves. Based on this, variational mode decomposition (VMD) is then introduced to separate explosion seismic waves and stress release-induced seismic waves from coupled vibration signals in the frequency domain. By utilizing the VMD separation, the composition and the amplitude and frequency characteristics of the rock vibration monitored in an actual deep tunnel blasting are investigated. The theoretical analysis and field investigation show that the vibration frequency of stress release-induced seismic waves is significantly lower than that of explosion seismic waves. Due to the existence of stress release-induced seismic waves with lower frequency, the coupled vibration amplitude is increased and vibration frequency is reduced. The monitored rock vibration in the near field is dominated by explosion seismic waves. However, in the far field, stress release-induced seismic waves become the major component due to their lower frequency and slower attenuation with distance. Extra care should be taken for the stress release-induced seismic waves in the far field. The stress release-induced seismic waves can be effectively reduced through shortening blast-created free surface sizes and increasing blasthole lengths moderately.

A large amount of mine water is generated during coal production, which not only damages the surface environment and ecology but also wastes groundwater resources in the mining area, exacerbating regional water scarcity. In this work, a novel zero liquid discharge technology combining selectrodialysis (SED) and bipolar membrane electrodialysis (BMED) was developed for the resourceful treatment of low-salinity mineralized wastewater. The SED stack had demonstrated to be workable for the elimination of multivalent ions. The BMED stack converts brine into acid and base. After SED, a high pure crude salt (~98%) was attained. Furthermore, under the conditions of a current density of 20 mA/cm2, a flow velocity of 20 L/h, and an initial acid/base concentration of 0.10 mol/L, the maximum concentrations of acid and base were found to be 0.75 mol/L and 0.765 mol/L, respectively, for a feed conductivity of 55 mS/cm. The cost of the entire electrodialysis stage was evaluated to be USD 1.38/kg of NaOH. Therefore, this combined UF-RO-SED-BMED process may be an effective strategy for the sustainable treatment of low-salinity mineralized wastewater.

In order to estimate the stability of slopes with geological defects during blasting excavations, the dynamic responses of a rock slope with a fault subjected to blasting seismic waves are studied. The SV-component of blasting seismic waves is considered and the fault is simplified as a semi-infinite crack in an unbounded space. In the background of an iron mine in central China, the relation between the stress field and the PPV of the incident wave is analyzed and the function of PPV threshold is deduced using both deterministic and probabilistic methods to evaluate the slope stability. Results show that the PPV threshold increases monotonically with the increasing frequency and reaches the lowest point at around γ1 = 14°, which should be proposed as the PPV threshold. The PPV threshold is with an about 50% failure probability when the mean values of mechanical parameters are taken. On the safe side, a more rigorous PPV threshold with only 5% failure probability is determined as 2.25 cm/s for f ≤ 10 Hz, as 2.25 cm/s-5.02 cm/s for 10 Hz 50 Hz. A through structural surface is likely to occur inside the northern slope once the PPV exceeds the proposed threshold.

The rapid heat loss and corrosion of nano-aluminum limits the energy performance of metastable intermolecular composites (MICs) in aquatic conditions. In this work, superhydrophobic n-Al/PVDF films were fabricated by the cryogel-templated method. The underwater ignition performance of the energetic films was investigated. The preparation process of energetic materials is relatively simple, and avoids excessively high temperatures, ensuring the safety of the entire experimental process. The surface of the n-Al/PVDF energetic film exhibits super-hydrophobicity. Because the aluminum nanoparticles are uniformly encased in the hydrophobic energetic binder, the film is more waterproof and anti-aging. Laser-induced underwater ignition experiments show that the superhydrophobic modification can effectively induce the ignition of energetic films underwater. The results suggest that the cryogel-templated method provides a feasible route for underwater applications of energetic materials, especially nanoenergetics-on-a-chip in underwater micro-scale energy-demanding systems.

During blasting in deep mining and excavation, the rock masses usually suffer from high in situ stress. The initial seismic energy generated in deep rock blasting and its attenuation with distance is first theoretically analyzed in this study. Numerical modeling of the multiple-hole blasting in a circular tunnel excavation under varied in situ stress conditions is then conducted to investigate the influences of in situ stress levels and anisotropy on the blasting seismic energy generation and attenuation. The case study of the deep rock blasting in the China Jinping Underground Laboratory (CJPL) is finally presented to demonstrate the seismic energy attenuation laws under varied in situ stress levels. The results show that with the increase in the in situ stress level, the explosive energy consumed in the rock fracture is reduced, and more explosive energy is converted into seismic energy. The increasing in situ stress causes the seismic Q of the rock mass medium to first increase and then decrease, and consequently, the seismic energy attenuation rate first decreases and then increases. Compared to the condition without in situ stress, the blasting seismic energy decays more slowly with distance under in situ stress. Then the seismic waves generated in deep rock blasting are more likely to reach and exceed the peak particle velocity (PPV) limits stipulated in the blasting vibration standards. Under non-hydrostatic in situ stress, the generation and attenuation of the blasting seismic energy are anisotropic. The highest seismic energy density is generated in the rock mass in the minimum principal stress orientation. Its attenuation is dependent upon the in situ stress aligning the wave propagation orientation.

The construction and long-term operation stage of the rock slope with argillaceous interlayer will be subjected to intermittent dynamic loads, such as blasting and earthquake. For the argillaceous interlayer in the rock slope, its rheological properties are not only related to the initial stress state caused by the gravity of the overlying rock mass but also affected by intermittent dynamic loads. In order to investigate the rheological properties of argillaceous intercalation under the combination of static and intermittent dynamic shear loads, the rheological tests of argillic intercalated soil samples under static shear, static and cyclic dynamic shear, and static and intermittent dynamic shear were carried out, and the rheological deformation characteristics of soil samples under different shear conditions were analyzed. The results show that when the soil specimens in the static shear rheological process are disturbed by intermittent dynamic shearing load, the intermittent dynamic disturbances might have no remarkable influence on the rheological deformation of the specimens if the initial static shearing stress and intermittent dynamic shearing stress were comparatively low. However, low-intensity intermittent dynamic disturbances might accelerate the rheological deformation process of the specimens remarkably if the initial static shearing stress state was close to their shearing strength. There was a stress threshold when the soil specimens failed under the static and cycling dynamic shear and static and intermittent dynamic shear, which is determined by the sum of static shear stress and dynamic shear stress peak. For rock slopes controlled by rheological weak structural planes and influenced by long-term blasting vibrations, the transient and long-term dynamic stability should be comprehensively analyzed.

High geotemperatures are encountered during tunnel construction in areas with complex geological structures, which can seriously affect personnel and equipment in the process of tunnel construction and operation. The Nige tunnel, a deep-buried extra-long tunnel, was selected to monitor the geotemperature during construction. The air, rock, and water temperatures during the tunnel construction were measured at the tunnel face, and the actual temperatures of the rock or water body at the tunnel face were measured by advanced drilling. The variation trends of the water temperature, air temperature, and flow of water with the tunnel mileage were analyzed. The differences in three measured rock temperatures in three advanced drillings were revealed. The results showed that the Nige tunnel had a maximum water temperature of 63.4 °C, maximum rock temperature (Rock T) of 88.8 °C, and maximum air temperature (Air T) of 56.4 °C. Increasing trends of the air, rock, and water temperatures with the tunnel’s horizontal distance and the buried depth (vertical depth) were obvious, and the geotemperature gradient was approximately 7.6 °C per 100 m. Additionally, the variation laws of the construction ambient temperature with time in a complete construction cycle showed four stage characteristics, and each stage presented different mathematical relationships. These findings will provide guidance for the construction of high geotemperature tunnels in future.

The initial stresses have a strong effect on the mechanical behavior of underground rock masses, and the initial stressed rock masses are usually under strong dynamic disturbances such as blasting and earthquakes. The influence mechanism of a blasting excavation on underground rock masses can be revealed by studying the propagation of stress waves in them. In this paper, the improved Mohr-Coulomb elasto-plastic constitutive model of the intact rock considering the initial damage was first established and numerically implemented in Universal Distinct Element Code (UDEC) based on the variation of the experimental stress wave velocity in the initial stressed intact rock, and the feasibility of combining the established rock constitutive model and the BB (Bandis-Barton) model which characterizes the nonlinear deformation of the joints to simulate stress waves across jointed rock masses under initial stress was validated by comparing the numerical and model test results subsequently. Finally, further parameter studies were carried out through the UDEC to investigate the effect of the initial stress, angle, and number of joints on the transmission of the blasting stress wave in the jointed rock mass. The results showed that the initial stress significantly changed the propagation of the stress waves in the jointed rock mass. When the initial stress was small, the transmission coefficients of the stress waves in the jointed rock were vulnerable to be influenced by the variation of the angle and the number of joints, while the effect of the angle and the number of joints on the stress wave propagation gradually weakened as the initial stress increased.

Evidence indicates that requesting video clips on demand accounts for a dramatic increase in data traffic over cellular networks. Caching part of popular videos in the storage of small-cell base stations (SBS) in cellular networks is an efficient method to reduce transmission latency and mitigate redundant transmissions. In this paper, we propose a commercial caching system consisting of a video retailer (VR) and multiple network service providers (NSPs). Each NSP leases its SBSs, with some price, to the VR for the purpose of making profits, and the VR, after storing popular videos in the rented SBSs, can provide better local video services to the mobile users, thereby gaining more profits. We conceive this system within the framework of a Stackelberg game by treating the SBSs as a specific type of resources. Then, we establish the profit models for both the NSPs and the VR based on stochastic geometry. We further investigate the Stackelberg equilibrium by solving the optimization problems in two cases, i.e., whether or not the VR has a budget plan on renting the SBSs. Numerical results are provided for quantifying the proposed framework by showing its efficiency on pricing and resource allocation.