Disaster Control Research Articles

Private security preparedness for disasters caused by fire

The subject of the research was the examination of the factors of influence on the preparedness of the private security for disasters caused by fire. In addition to determining the preparedness index, there are deeper insights into the interrelationships between various selected variables and the level of preparedness of members of the private security. Using the random sampling method, 300 adult members of the private security were selected, and they participated in the research. The results of the research indicate that members of private security were not sufficiently prepared to react to fires. The research results could be used as a starting point for conducting further research in this area since the improvement in training of security personnel plays an important role in disaster control and prevention, thereby producing safer and more secure work environment and society.

Recognition and prevention of rockfall vulnerable area in open-pit mines based on slope stability analysis

Because of a wide distribution range, sudden occurrence, and high frequency of rockfall disasters on the slope of open-pit mines, it is difficult to effectively control the rockfall disasters in open-pit mines. The slope stabilities of slopes of 13 typical sections in the Changshanhao open-pit mine were calculated using 3DEC software, and the vulnerable area of each slope section was determined. These areas were analyzed as high-incidence areas of rockfalls. Combined with the field geological conditions, the slopes of the W6 and W8 sections where rockfall disasters easily occur were selected to study the motion characteristics of rockfalls, including the trajectory, landing distribution, bouncing height, and total kinetic energy using Rocfall software. According to different distribution characteristics of high-incidence areas of rockfall disasters on a slope, the gravel cushion and protective net methods are proposed to control rockfall disasters. The effectiveness and reasonableness of prevention methods were validated using numerical simulation, proving a good basis for scientific prevention and control of rockfall disasters in open-pit mines.

Experimental Study Via Dynamic Prediction Model on High Pressure Hydraulic Slotting and High Efficiency Gas Drainage Technology under Complex Geological Conditions

In view of the difficult problem of dynamic disaster prevention and control in deep high gas, high stress and low permeability coal seam, the change law of drilling stress after seam cutting through drilling and bedding drilling is revealed by using numerical simulation method. The high-pressure hydraulic slotting method is used in Xinji Mining Area to carry out pressure relief and permeability increase test on coal seams. The test results are as follows: the slotting radius reaches 2.5m, and the net amount of gas extraction is 4.5 times higher than that of ordinary drilling holes, so as to realize efficient gas extraction in coal seams and reduce the risk of coal seam outburst. The technology of high-pressure hydraulic slotting, pressure relief and permeability enhancement can be used as a supplementary means for the prevention and control of coal seam dynamic disasters in deep mines.

Risk assessment of water and mud inrush in a tunnel in Chongqing based on analytic hierarchy process

Water and mud inrush is one of the typical geological hazards during tunnel construction in karst area. In weight of water or mud inrush risks of karst tunnels are studied and the index system for water and mud inrush risk evaluation is established based on analytic hierarchy process. The analysis shows that geological structure, formation lithology and groundwater level are the main control ingredients of water or mud inrush risk；geographic and geomorphic conditions, attitude of rock formation are the minor significant factors；surrounding rock mass classification , rainfall are the least important elements. Aiming at a tunnel in Chongqing, combining with the actual geological situation of the tunnel site, the evaluation model is used to evaluate the risk of water and mud inrush in each section, which provides a certain theoretical basis for the prevention and control of water and mud inrush disaster during the tunnel construction.

Recognition and Mapping of Landslide Using a Fully Convolutional DenseNet and Influencing Factors

The recognition and mapping of landslide (RML) is an important task in hazard and risk research and can provide a scientific basis for the prevention and control of landslide disasters. However, traditional RML methods are inefficient, costly, and not intuitive. With the rapid development of computer vision, methods based on convolutional neural networks have attracted great attention due to their numerous advantages. However, problems such as insufficient feature extraction, excessive parameters, and slow model testing have restricted the development of this technology. This research proposes a new RML framework based on a new semantic segmentation network termed the fully convolutional DenseNet (FC-DenseNet). In this network, the features extracted from each layer are repeatedly used in a dense connection, and the parameters are controlled by a bottle-neck structure. Meanwhile, the structure of the encoder-decoder solves the problem of the slowness of model testing. Finally, the landslide influencing factors are added, which enriches the training data. To verify the effectiveness of the proposed method, we focused on several deep networks for comparison and analysis. The results show that FC-DenseNet can better recognize the boundary and interior of landslides, and there are fewer missing and excessive recognition results. The kappa value of the new method is 94.72% in Site 1, which is 6% and 4% higher than that of U-Net and ResU-Net, respectively, and 94.56% in Site 2, which is 6% and 3% higher than that of U-Net and ResU-Net, respectively, indicating that FC-DenseNet has great potential in RML applications.

Prediction of Rockburst Risk in Coal Mines Based on a Locally Weighted C4.5 Algorithm

Rockburst is a dynamic phenomenon characterized by the sudden, abrupt, and violent release of deformation energy in coal and rock masses around mine shafts and slopes that can result in considerable destruction. For prediction and evaluation methods are essential for the prevention and control of rockburst disasters, many machine learning methods are developed for this purpose. To accurately predict rockburst risk, the present study addresses this issue by developing a locally weighted C4.5 decision tree algorithm for predicting the risk of rockburst in coal mines. In the proposed processing, the minimum description length principle is first applied to discretize the continuous attribute data in the raw training dataset. Then, the prediction model based on the C4.5 algorithm is trained by 10-fold cross validation using the adjacent samples selected by the k-nearest neighbors method. Finally, the decision tree is completed by applying pessimistic pruning. The rockburst prediction accuracy of the proposed locally weighted C4.5 algorithm is compared with that obtained by the standard C4.5 algorithm based on field data derived from the Yanshitai coal mine, Chongqing, China. The rockburst risk prediction accuracies obtained by the proposed and standard C4.5 algorithms for the samples in the testing dataset were 100% and 71.43%, respectively. Accordingly, the proposed locally weighted C4.5 algorithm greatly outperformed the standard C4.5 algorithm for the prediction of rockburst risk based on the data considered.

The Formation Mechanism of Surface Landslide Disasters in the Mining Area under Different Slope Angles

Slope stability analysis is important for the safe mining of mineral resources. The collapse of goafs in loess gullies can lead to natural disasters such as surface landslides. In this context, this study analyzes monitoring data obtained from surface observation in the Shendong mining area of the Hanjiawan coal mine based on the geological conditions therein. The monitoring results show that the working face experiences a starting period, an active period, and a declining period, from the start of mining to the end of the working face. At the initial mining stage, there is no evident surface movement or deformation in the mining area. When the advance distance of the 12106 working face is between 13 m and 109 m, the surface movement and deformation vary significantly, and the maximum subsidence reaches 1963 mm, which is enough to cause landslides. We select the physical and mechanical parameters of the rock and soil in the mine and then simulate the formation mechanism of surface landslides under different slope angles of the mining area using FLAC3D software. Because of the collapse of the mined‐out area, the overlying strata structure is destroyed, the subsidence basin is shifted to the center as a whole, and the slope mass is subjected to tensile and compression deformation, resulting in plastic damage, which develops downward along the crack and leads to a collapse because of the discontinuous movement and deformation of the surface; moreover, step‐type ground fissures are produced. The results also show that when the slope angle is greater than 60°, the displacement of the slope mass is not uniform, and the rock stratum in a position with large displacement loses its support, leading to landslides; when the slope angle is less than 30°, the bedrock surface forms a sliding surface and develops to the surface, thus decreasing the possibility of landslides. Based on the stability analysis of the collapsed slope in the goaf of the loess gully, a scientific basis is provided for the effective prevention and control of geological disasters in the Shendong mining area.

An analytical approach to estimate the mechanical state of roof strata in underground longwall mining

The movement and collapse of roof strata in underground longwall mining is a key trigger factor for the occurrence of dynamic disasters. An accuracy estimation of roof strata mechanical state is critical for the prediction and control of dynamic disaster, such as coal burst and coal-and-gas outburst. An analytical approach is proposed in this work to estimate the mechanical state of roof strata in underground longwall mining. To do so, the unit width of roof strata is considered as a beam structure. A system of 4 simulations differential equations is proposed with 4 local slope data as input parameters to derive the mechanical expression of suspending roof strata. A differential evolution algorithm is further adapted to solve the equation system. In addition, a set of verification tests is carried out to showcase the feasibility and robustness of the proposed method. The results show that the average relative errors of 10 independent tests reach a high accuracy, which is less than 1% for the strata mechanical state control parameters. By using the estimated results, the slope, bending moment and shear force of suspending strata are derived. Moreover, the slope data sampling strategy is also devised. The parameters bound determination method is also proposed to ensure the calculation convergence. The local slope based analytical method proposed in this paper is a feasible approach to estimate the mechanical state of suspended roof strata before first weighting.

Multifield Environmental Analysis and Hazards Prevention of Steeply Inclined Deep Coal Mining

Due to the different in‐situ stress level, mining stress state, and surrounding rock properties of steeply inclined deep coal mining, the mutation mechanism of underground engineering rock mass is complex. This paper studies the cause and control of mining disaster of steeply inclined deep coal resources in Wudong coal mine. The results show that the structural field is the key of multifield analysis, and particularly a large area of suspended roof is easy to expand energy and induce dynamic hazards. By means of borehole television‐ (BT‐) transient electromagnetic (TEM) detection, it is found that there are hidden dangers of roof safety and suspected water hazards in Wudong coal mine, and the roof above the detection area (+575 m south roadway to 2250–2600 m) is in a suspended state; there is a suspected water‐rich area in the range of 2320–2340 m and 2390–2400 m, and the lowest vertical height is +613.8–+615.5 m. Exploring and releasing the water in the aquifer effectively reduced the water pressure; in +575 m south roadway, +587 m measure roadway, and blasting chamber, the suspended roof blasting holes are constructed. Microseism‐ (MS‐) TEM monitoring shows that the apparent resistivity fluctuates significantly, the microseismic energy and events have been significantly reduced, and it is maintained at a low level for two consecutive weeks, confirming the effectiveness of the stable release of the high‐stress roof in the +575 m near stope area; at the same time, the safeguard measures for long‐term roof dynamic monitoring are constructed.

葡萄自然灾害绿色防控技术研究进展

葡萄自然灾害绿色防控技术研究进展

Transient analysis of a Markovian N-policy queue with system disaster repair closedown setup times and control of admission

Transient analysis of a Markovian N-policy queue with system disaster repair closedown setup times and control of admission

Risk assessment of washout by slope flow along long-distance-pipeline based on quantitative index cloud reasoning-integrated weighting

The washout by slope flow along long-distance oil & gas pipelines is a common geological hazard that occurs when pipelines pass through the alluvial-proluvial fan section of mountain piedmont. Accurate and effective evaluation of the risk of single washout by slope flow is an important basis for disaster prevention and control decisions. According to the characteristics of the lack of basic research data in the development area of washout by slope flow, the complexity of the risk assessment structure and the strong randomness and ambiguity of the multi-index system, on the basis of rapid acquisition of initial data of indicators through field survey, simple experiment and sampling analysis, a quantitative index cloud reasoning risk evaluation model for slope flow washout of pipeline was established by introducing single-condition and single-rule cloud reasoning with summation integration weighting algorithm, and carry out instance verification. The evaluation results of 11 samples showed medium and relatively high risks, and the overall distribution trend is relatively concentrated. Compared with the results obtained by the entropy weight-extension method and the standard recommendation method, the proposed method is more in line with the small-scale disaster background analysis and the reality of the study area, and it’s also more beneficial to ensure the safe operation of pipelines. In this method, the obtainment of the source data is reliable, objective, and the preprocessing is simplified, the index weighting and classification are more reasonable, and the evaluation process takes into consideration of both the randomness and ambiguity of the system, which improves the accuracy and effectiveness of the evaluation results. It also provides a new way of thinking to other related research.

Subsidence Control Design Method and Application to Backfill‐Strip Mining Technology

Intensive and massive coal mining causes a series of geological hazards and environmental problems, especially surface subsidence. At present, two major types of subsidence control technology are applied: backfilling technology and partial mining technology. However, the cost of backfill mining is high and partial mining has a low recovery ratio. Therefore, the backfill‐strip mining is used to solve the problems of high cost and shortage of filling materials in coal mines at present. A subsidence control design method of backfill‐strip mining was proposed in this paper based on the subsidence control effects and economic benefits. First, the stability of the composite support pillar of the filling body and coal pillars in the backfill‐strip mining is analyzed, and the values of the main subsidence influencing factors that include the filling material, the size of the backfilling working face, caving mining face, and residual coal pillar are preliminarily determined. Then, the surface movement and deformation are predicted based on the equivalent superposition probability integral method (PIM). The subsidence influencing factors are optimized and determined by comparing the requirements of the safety fortification index of the antideformation ability of surface buildings, resource recovery rate, and coal mining cost. Finally, the mining scheme design parameters of the backfill‐strip mining technology are determined. This method is applied in the subsidence control design of backfill‐strip mining in the Ezhuang coal mine. Research results show that backfill‐strip mining can ensure the safety of surface buildings, increase the resource recovery rate, and reduce coal mining costs through the reasonable design of this method. This study can provide scientific guidance for subsidence disaster control, prevention, and engineering design in backfill‐strip mining.

Experimental study of the effects of ullage height on fire plume centerline temperature with a new virtual origin model

Investigating the evolution of the fire plume centerline temperature has both fundamental and practical importance to process safety, risk analysis and disaster control. In practice, ullage height (distance between the fuel surface and the container upper rim) is a common boundary condition that affects the burning intensity and the flaming characteristics. In this study, a series of experiments were conducted to reveal the effects of ullage height on the evolution of the heptane fire plume centerline temperature. The tested ullage height was systematically changed from zero to the value at which the flame self-extinguished. Results showed that, as ullage height increased, the fire plume centerline temperature first decreased and then slightly increased. By comparing the model predictions of previous classic models with the tested results, this study proved that previous classic models are not capable in predicting temperature profiles under high ullage height conditions. Based on physical and dimensionless analysis, a new virtual origin model was established to quantify the effects of ullage height on the virtual origin. A more universal plume centerline temperature model, which is capable to predict the centerline temperature profiles with any ullage height conditions, was proposed and validated by literature experimental data.

COVID-19 pandemic and legal issues

Covid-19의 현재상황에서 헌법과 개별법률의 법적 근거가 충분한 지 여부에 관계없이 자유에 대한 현재의 제한조치는 정당화될 수 있다. 특히 감염위험 증가, 긴 잠복기, 감염된 사람들의 증상 부족 및 때로는 치명적인 질병경과로 나타나는 Covid-19 대유행의 특수한 상황을 고려할 때 건강을 보호하기 위한 과감한 조치가 정당화 될 수 있다. 그러나, 대유행이 길어질수록 즉각적인 조치들뿐만 아니라 국가적 맥락을 넘어서는 다양하고 사회적, 경제적 결과를 고려해야 한다. 본 연구에서는 이러한 배경에서 코로나 19 전염병 시대에 기본권을 다루는 방법에 대한 논의의 맥락에서 여기에서 관련된 법적 문제를 검토하고 비례성의 원칙에 대한 고려도 필요하다는 점을 강조하고 있다. COVID-19 대유행은 한편으로는 우리 의료시스템의 부적절함을 보여줄 뿐만 아니라 보호장비의 가용성과 같은 재난통제의 결함과 다른 한편으로는 최악의 상황을 피하기 위해 노력하고 있다. 그럼에도 코로나 위기 상황에서도 새로운 비교형량도 우선 고려해야 한다. 하지만 특히 많은 사람들이 인류보다 안전에 더 중점을 두기 때문에 개별 사례에서 무게를 두는 것은 쉽지 않다. 이와 관련하여 우선 코로나 바이러스 위기를 극복하는 데 가장 중요한 감염병예방법의 규정에 대한 개요와 위기로 인한 각종 조치들로 인한 법적 분쟁사례들에 대해 실무적인 측면에서의 현황과 개별적인 조치들의 법적 측면에서의 문제점들을 나누어 검토하고 있다.In the current context of Covid-19, the current restrictions on freedom can be justified, regardless of whether the constitution and the legal basis of individual laws are sufficient. In particular, taking drastic measures to protect health can be justified given the specific circumstances of the Covid-19 pandemic, which manifests itself as an increased risk of infection, long latent period, lack of symptoms in infected people, and sometimes fatal disease progression. However, as the pandemic lengthens, it is necessary to take into account not only immediate measures, but also diverse social and economic consequences beyond the national context. Against this background, this study emphasizes the need to review the legal issues involved here and to consider the principle of proportionality in the context of discussions on how to deal with basic rights in the era of the Corona 19 epidemic. The COVID-19 pandemic not only shows the inadequacy of our healthcare system on the one hand, but also strives to avoid disaster control deficiencies such as the availability of protective equipment and the worst on the other. Nevertheless, even in the corona crisis situation, a new comparative sentence should also be considered first. However, it is not easy to weigh in individual cases, especially as many people put more emphasis on safety than humanity. In this regard, first of all, it is reviewed an overview of the regulations of the infectious disease prevention method, which is the most important in overcoming the coronavirus crisis. This issue was also discussed the current situation in the practical aspect of legal dispute cases caused by various measures arising from the crisis. In this careful analyses on the important legal problems of individual measures is also valuable for checking the legitimacy of actions taken regularly, especially taking into account ongoing emergencies, to evaluate lighter response options, and to readjust if necessary.

Types, characteristics, distribution, and genesis of pockmarks in the South China Sea: insights from high-resolution multibeam bathymetric and multichannel seismic data

ABSTRACT Ubiquitous pockmarks in continental margins are important to understand the tectonic and sedimentary history and flow activity of their host margins. The study of an extensive field of pockmarks in the South China Sea (SCS) is important both scientifically and economically, for the exploration of oil, gas, and gas hydrate resources and the prevention and control of marine geological disasters. We report our new findings on the characteristics, distribution, and genesis of pockmarks in the SCS based on interpretation of high-resolution multibeam bathymetric data and multichannel seismic profiles collected in the past decade. Three pockmark fields (total area 572,824 km2), are recognized in the northern, western, and southern continental margins of the SCS. The pockmarks are highly variable in shape: circular, elliptical, crescent-shaped, elongated or forming a chain in plan view and U-, V- or W-shaped in cross-section. Pockmarks are normally 10–200 m in diameter, with maximum diameters/axial lengths of 7.3 km for circular, 5.5 km for elliptical, 8.6 km for crescent-shaped, 9.5 km for elongated, and 30 km for chain-type pockmarks. Pockmarks are normally less than 35 m deep, with a maximum depth of 341 m at the southwestern SCS margin. These pockmarks might have originated from methane seepages or from pore fluids from deeper sources, which migrated vertically along gas chimneys, mud diapirs, mud volcanoes, faults or buried channels. In addition to possible structural controls, the pockmark morphologies are affected by bottom currents.

Breaking and Instability Movement Characteristics of High-Position Double-Layer Hard Thick Strata due to Longwall Mining

With multilayer hard roof occurring above the mining area, the strata behaviors will be significantly affected by their special characteristics and interaction. In this paper, relying on the mining background of panel 1061 of a coalmine, the breaking instability of double-layer hard thick strata (DLHTS) and the precursory information of disasters are studied by using theoretical analysis, numerical simulation, and physical simulation. Results show that the DLHTS have bearing, blocking, and controlling effects. Prior to DLHTS breaking, the horizontal development of stress concentration zone and plastic zone can be controlled, and the overburden movement is gentle, while during the breaking process, the stress drops abruptly, the plastic zone expands longitudinally rapidly, the overburden moves notably, and the energy release is sharp, which is likely to directly cause strong dynamic pressure. Moreover, the DLHTS can interact with and influence each other; that is to say, the breaking of lower magmatic rock (LMR) can provide sufficient space for that of upper magmatic rock (UMR), while the UMR breaking can promote the LMR periodic breaking in turn and cause its secondary instability, thereby easily causing complex or composite dynamic disasters’ formation. Hence, compared with single hard thick stratum occurrence, the strata behaviors affected by DLHTS breaking and instability are normal and more intense. Study results can provide a scientific basis for the prevention and control of dynamic disaster with hard thick stratum occurrence and important guidance value for promoting safe and efficient production of coalmines.

Research on the Attenuation Characteristics of AE Signals of Marble and Granite Stone

When an underground rock is deformed or fractured by an external or internal force, the energy will be released in the form of an elastic wave, which is known as the acoustic emission (AE) phenomenon. Extracting useful information from complex AE signals for the early warning of fracture characteristics and the damage monitoring of rock materials is of great significance for the prevention and control of dynamic disasters in coal mines. In this work, by taking rod-shaped rocks and plate-shaped rocks with different lithologies as the research objects, the elastic wave propagation characteristics of the rod-shaped rocks and plate-shaped rocks were studied by a self-constructed experimental platform. The results demonstrate that the elastic wave attenuation of the rod-shaped marble was the fastest, and the elastic wave attenuation characteristics of the three groups of rod-shaped granite were similar. The attenuation of the P-wave preceded that of the S-wave. With the increase in the propagation distance, the amplitude of the large-scale plate-shaped rock showed an approximate exponential attenuation characteristic. The elastic wave attenuation of the plate-shaped granite in the 0° direction was stronger than that of the plate-shaped marble, and it was weaker than that of the plate-shaped marble in the 45° and 90° directions. The energy changes in marble were more severe than those in granite. The main dominant energy of the AE signals of experimental rock was concentrated in the range of 0–176.78 kHz, and part of the residual energy was located in the high-frequency band of 282.25–352.56 kHz.

Gas Displacement Engineering Test by Combination of Low and Medium Pressure Injection with Liquid CO2 in High Gas and Low Permeability Coal Seam

Mining high-gas coal seams in China has the characteristics mining of deep, high storage and low permeability, and low drainage efficiency, which seriously restrict the efficient prevention and control of mine gas disasters. Based on the characteristics of low viscosity and permeability, phase change pressurization, and strong adsorption potential energy of liquid CO2, the technology system of liquid CO2 displacement for high-gas and low-permeability coal seam was developed, and field industrial of low-pressure (0.5~2.5 MPa) and medium-pressure (2.5~15.0 MPa) combined injection test was carried out. In this test, the mode of injection followed by drainage was adopted, and the gas drainage effect was investigated for 30 days. The test results show that the effective influence radius of CO2 in this test is 20 m, and the liquid seepage radius is 5 to 7 m. After the injection of liquid CO2 into coal seam, the average gas drainage concentration and drainage purity of all drainage holes were increased by 3.2 and 3.4 times, respectively, and the gas promotion effect was significant. Taking the liquid CO2 low-medium-pressure displacement gas test area as the calculation unit, from the comprehensive benefit analysis, compared with the original drainage mode, the liquid CO2-combined pressure injection process can save 34.7% of the engineering cost and shorten the gas drainage standard time by 45.9%. Therefore, the application of this technology has important technical support and reference significance for the efficient management of gas in the same type of mine.

Investigation on coal spontaneous combustion in the gob of Y type ventialtion caving face: A case study

Gas and coal spontaneous combustion (CSC) compound disasters have become a common mode of serious accidents in coal mines. This study is aimed at revealing the characteristics of such compound disasters in the gob of Y-type ventilation fully mechanized top coal caving face with a high-level drainage roadway (HLDR) (hereafter referred to as “Y+HLDR” working face) and providing a theoretical basis for disaster prevention and control. With the W1310 fully mechanized working face of Gaohe Coal Mine taken as the research background, the distribution law of gas concentration field in the gob of the “Y+HLDR” ventilation mode under different air supply conditions was numerically simulated with the aid of COMSOL, and the area of gas and CSC compound disaster in the gob was divided quantitatively. The results show that data obtained from the field experiment coincide with the simulation results, which verifies the effectiveness of the simulation; Meanwhile, with the increase of air supply volume, the gas concentration near the working face is significantly reduced, and high-concentration gas is transferred to the deep part of the gob. The area where CSC induces gas explosions is divided by superimposing the gas and oxygen concentration fields that meet the conditions of compound disaster occurrence on the gob floor. It is concluded that the range of area with compound disaster risk is positively correlated with the air supply volume. The results of the simulation provide important theoretical guidance for the prevention and control of gob disasters.