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Seabed fluid migration is a critical process that involves the transport and movement of liquids, gases, and seawater within and outside the seabed, which has significant impacts on the genesis, development, and evolution of seabed geological disasters. Notably, typical disasters such as submarine landslides in the sea area of China demonstrate a strong relevance with seabed fluid migration phenomena. In this paper, we analyze the distribution characteristics of typical fluid migration system types and geological disaster causes taking the northern South China Sea as an example, and we summarize the observation and investigation methods of seabed fluid migration. Furthermore, we propose the primary issues and content that must be addressed in the study of disasters induced by seabed fluid migration and their prevention and control. Specifically, we suggest that research should focus on the three phases, namely disaster genesis induced by deep high-pressure fluid migration, disaster development caused by gas hydrate decomposition and fluid migration, and disaster triggering resulting from ocean water movement. Based on breakthroughs in technological bottlenecks such as multi-system integration, multi-scale cooperation, and multi-dimensional information processing in deep-sea exploration, we must conduct in-depth research on the evolution mechanisms of seabed disaster genesis, development, and triggering under the influence of seabed fluid migration. Additionally, we must develop theoretical methods for seabed disaster risk prevention and control under the coupled effects of seabed fluid migration, geological environment, and human activities.

Deep coal resources are the crucial backup for China's energy security in the future. However, large deformation and instability of rock mass in deep roadway engineering still poses serious problems in the deep "three high and one complex" geomechanical environment. Therefore, this study departed from the support surrounding rock interaction and developed a series of NPR anchor bolts/cables with high strength, high constant resistance and large deformation mechanical properties. It constructed the constitutive equation of NPR anchor bolts, and carried out comprehensive mechanical tests indoor and on-site to verify the unique mechanical properties of NPR anchor bolts/cables. This study analyzed the interaction relationship between NPR support and surrounding rock, derived the constitutive relationship of rock mass supported by NPR, and elucidated the excavation compensation mechanical effect after adopting NPR coupling support, which revealed the high pre-stress NPR coupling support mechanism. By drawing on the actual working conditions of Daqiang Coal Mine, this study proposed the NPR support technology for intensive chambers group of deep pump house suction well with NPR bolt /cable as the core. The numerical analysis and field monitoring data show that the high prestress NPR coupling support technology can significantly improve the bearing characteristics of the support surrounding rock, effectively reduce the distribution and development range of the plastic zone of the rock mass in the roadway engineering, homogenize the support surrounding rock stress field, and reduce the overall deformation of the surrounding rock by more than 68 %, ensuring the long-term stability of the rock mass in the deep roadway engineering. The research results can provide reference for stability control of deep roadway engineering under similar conditions.

Coal is the principal energy of China, and the coal industry is an important basic industry related to the energy security. For a long time, the underground coal resources mining in China has always been based on the longwall 121 mining method. This mining system has many problems such as waste of coal resources, high rate of entry excavation and concentrated stress of coal pillars. In order to solve the three bottlenecks and prominent problems of “safety, mining cost and coal recovery rate” existing in the current mining system, we established a mining engineering model based on the mining damage invariant equation, analyzed the mechanical principle of automagical entry formation without coal pillars. On this basis, the key technologies of 110 and N00 mining method, such as directional presplitting and pressure relief of roof, NPR bolt/cable support are developed. The technical objective of “being able to control the roof, cut off the roof, make the roof easy to collapse and protect the entry rib” has been achieved. The 110 mining method of automagical entry formation without coal pillars and the N00 mining method at different development stages have been formed. The 110 mining method unifies the two sets of processes of coal mining and excavation initially, so that each coal mining face can dig one less mining entry, and no pillar mining is realized. The N00 mining method is based on the 110 mining method, which completely unifies the two processes of coal mining and excavation. The mining pressure is used to automatically form the roadway, thus eliminating the excavation of roadways and thoroughly eliminating the long-standing problem of strained relations of mining and excavation. The field practice shows that the 110 mining method cuts off the stress transmission between the roof of the goaf and the roof of the entry. The mine pressure and self balance of the surrounding rock of the retained entry is realized by using the crushing and swelling property of the collapsed gangue. The N00 mining method innovates the original mining technology, changes the layout of the traditional mining system, and realizes no entry digging and automatic entry formation in the whole mining area.

There are many challenges in the process of underground engineering construction, such as high stress, extremely soft rock, strong mining and other complex conditions. The surrounding rock is difficult to control and its deformation is serious due to the stress concentration and energy accumulation, leading to frequent roof fall, collapse, rock burst and other accidents. Anchor bolt is the main support mode of underground engineering chamber. In order to absorb energy released by surrounding rock deformation and control the deformation of surrounding rock, it is necessary to develop energy-absorbing bolt with high constant resistance, high elongation and high prestress. This paper summarizes and analyzes the development process, performance test and field application of energy-absorbing bolt. Energy-absorbing bolt absorb energy by structural slip and material deformation. According to the working principle, the energy-absorbing bolt can be divided into three types: rod structure type, mechanical structure type and body material type. Compared with structural energy-absorbing bolt, the structure of material energy-absorbing bolt is relatively simple, which can give full play to the mechanical properties of material. The author's team developed a new constant resistance energy-absorbing bolt, and carried out static tensile and dynamic impact tests. The results show that the bolt has high strength, high elongation and high energy absorption characteristics, which can meet the requirements of surrounding rock control under complex conditions. In the future, the test, design, construction and acceptance standards of the constant resistance energy-absorbing bolt should be formulated to realize its application in underground engineering in different fields such as mine, traffic, municipal engineering and water conservancy.

Large-scale topping deformation occurred in the southwest stope of Changshanhao Open-pit Gold Mine in Inner Mongolia.Through systematic investigation of the engineering geological conditions and rock mass structure types, the deformation characteristics and failure mechanism of the stope are studied in depth.Taking this project as an example, the 3DMine-FLAC3D large-scale complex geological body high-precision coupling modeling method and modeling process are introduced in detail.Based on this, a slope reinforcement scheme with constant resistance and large deformation anchor cable is proposed, and a numerical simulation method is used to make a comparative study with the original support scheme.The research results show that the geological structure of the southwest stope is complex.Faults and joints are developed.The rock mass in the toppling area is mainly slate and schist with low bending strength, and small deformation anchor cables are used in the supporting structure, which cannot resist large slope deformation.The combined effect of these factors leads to the occurrence of dumping instability.The reinforcement scheme to constant-resistance and large-deformation anchor cables can effectively control the slope deformation and a better support effect is obtained.

In recent years, the intensity and frequency of landslide geological disasters have been increasing year by year.In the process of landslide occurrence, the traditional prestressed anchor cable can not resist the large deformation of rock and cause problems such as breaking and failure.In response to the above problems, three different types of high-resistance large deformation anchor cables (NPR anchor cables) have been independently developed.Its core structure consists of a constant resistance device connected with a traditional anchor cable.Then, through the field static tensile test, it is confirmed that the cable can provide a maximum working resistance of 850 kN and a large deformation of 2 000 mm.Secondly, using STATIC and GENERAL quasi-static analysis method in ABAQUS, the numerical simulation analysis of the stress-strain characteristics of the constant resistance device under static tension is carried out.The analysis results prove that the NPR anchor cable stretching process is a process of constant resistance and energy absorption.Finally, through field application, it is verified that the NPR anchor cable structure can be deformed greatly with the instability of the slope, which avoids the traditional anchor cable being broken due to large deformation.It achieves the goal of intelligent integration of landslide hazard prevention, monitoring and forecasting and provides a scientific basis for reasonably explaining the relationship between the law of landslide migration and the monitoring and early warning curve.

Flexural toppling failure is a complex process of landslide disaster,on which the researches gradually become the key and difficult points in the academic field.Taking an open-pit mine slope failure due to flexural toppling as an example,this study attempts to introduce discontinuous deformation analysis method(DDA) to simulate the complex failure process.Firstly,the way to introduce artificial joints into DDA model to simulate fracturing through the intact rock masses during the flexural toppling process is analyzed.By comparing with the failure phenomena of field case,the proper way to introduce artificial joints is obtained,and the results confirm DDA is a proper method to analyze flexural toppling failure of numerical method.The simulation process shows that the lower part slope fails firstly because it is unable to support the upper rock layers,and then the upper part slope fails due to the loss of the support from the lower part slope.The research on the reinforcement scheme against flexural toppling deformation of the slope indicates that if the reinforcements depend on the strength of the ordinary anchor cable,local failure of the anchor cables becomes very easy,which could induce the failure of the whole anchor cables finally.

Based on the theory of “cutting short-wall beam”,the automatic cutting-in coal-free pillar mining technology for roof-cutting pressure relief is widely used in engineering practice.However,due to the limitation of the numerical modeling of large deformation materials,the numerical simulation analysis of mine pressure distribution based on theory of truncated short wall beam has not been studied.In this paper,the numerical simulation model of NPR bolt/cable is established at the first based on the constant resistance mechanical mechanism of the NPR bolt/cable in the supporting process,achieving the goal of numerical and programmed calculation of large deformation materials .Then,based on the background of Hecaogou No.2 coal mine engineering,mine pressure in longwall mining is continuously monitored on-site.Finally,the numerical simulations and comparative analysis of mine pressure distribution by applying theory of truncated short wall beam on 1105 working face were made through FLAC3D program.The paper reveals the different characteristics of the distribution of abutment pressure under traditional technology and the working face of theory of truncated short wall beam,and this lays a theoretical foundation for the study of stress field distribution and the rule of temporal and spatial variation of rock mass structure using theory of truncated short wall beam.

Uniaxial tensile simulations were carried out in OA,OB and OC directions of kaolinite at different temperatures by using molecular dynamics simulations.The deformation and failure processes of kaolinite were studied at the atomistic scale.The change of microstructure,deformation mechanism and temperature effect of tensile mechanical properties of kaolinite at different temperatures were also analyzed.This work would be helpful to understand the mechanisms of large deformation and failure of soft rock.The results indicated that the increasing of temperature results in the thermal expansion of kaolinite after relaxation.Once the crack nucleation appears,it propagates very quickly and leads to a sharp decrease in stress along OA and OB loading directions.The layer separation occurs during loading along OC direction,while the structure could fail since the hydrogen bonds are broken.The mechanical properties of kaolinite have a strong dependence on temperature.There is a negative correlation between tensile strength,Young’s modulus and temperature.With the increase of temperature,the tensile ultimate strain and residual strength tend to decrease,and the strength attenuation coefficient tend to increase.In addition,OC direction is the most affected by the temperature,followed by OB direction,and OA direction is the least affected.

The problem of water inrush is more prominent in deep coal mining.Due to complexity of geometry for rock mass fractures, there are still many difficulties in studying the seepage characteristics, especially, the rule of fluid flow in the cross fracture are less reported.In this paper, the seepage of cross fracture, with nine different sizes, was studied by using two-dimensional numerical analysis software Fluent.The size effects of fractures were analyzed from four aspects:pressure field, velocity field, water distribution field and fluid flow characteristics.The results show that the velocity and pressure in the range of longitudinal fracture are much larger than those in transverse fracture.The tendency of velocity with time is consistent with that of pressure at the same point.There is a critical value of longitudinal fracture between 0.1 mm and 0.3 mm that the surface tension is equal to the sum of the weight of the water and atmospheric pressure imposed by gas;and there is another critical value of transverse fracture between 0.3 mm and 0.5 mm that the surface tension equals the applied force of gas.

Impact rockburst is induced by the combined static and dynamic loads after excavation.There are two types of impact rockburst experiments，one is induced by changing the static load and another is induced by changing the amplitude of dynamic load.The sandstone fragments after these two experiments were collected.Meanwhile，the sandstone fragments generated from the similar compression experiment under static load were collected too.And the mass， length，width and thickness of each fragment has been measured respectively.The quantities and mass distribution of fragments with coarse，medium，fine and micro grains in different size ranges，and size distribution were further analyzed.The crushing level and shape characteristic of fragments were obtained.Then the fractal dimensions were calculated.The results show that the degree of crushing level of fragments from impact rockburst is higher and with obvious slice shape；the ways of combined static and dynamic loads have a little effect on the crushing level and scale characteristic of fragments from impact rockburst experiments；energy dissipation from impact rockburst experiments is higher than that of similar compression experiment.

Water absorption is one of the most important factors which can induce serious rock deformation and failure. Water vapor absorption experiments were carried out on rock samples collected from three different coal mines. Meanwhile, the mineral components, microstructure features and pore structure parameters were determined by means of X-ray diffraction, scanning electron microscopy and mercury intrusion porosimetry in order to comprehensively analyse the effects of clay minerals and micropore structure on water vapor absorption of the investigated rock samples. Results have shown that the patterns of the water vapor absorption curves of the three types of rocks were all characterized by a similar kind of dynamic process with decreasing water vapor absorption rate which could be well fitted by a negative exponential function. However, significant differences were found in water vapor absorption ability among the three types of rock samples which could be sorted in an order of Daqiang conglomerate > Shajihai mudstone > Halagou sandstone. Furthermore, the greater abundance of clay minerals contained in rock samples, especially smectite, the more and quicker water vapor absorption. Meanwhile, water vapor absorption is positively correlated with effective porosity, but is negatively correlated with fractional dimension which indicates that the bigger the effective porosity the greater the water vapor absorption ability and the more complicated the pore structures the weaker the water vapor absorption ability.

Gob-side entry retaining through precut overhanging hard roof (GERPOHR) method is one of the commonly used methods for nonpillar mining. However, feasibility studies of controlling rockburst by this method are few. Rockburst occurs in hard thick strata with a higher probability, larger scale, and higher risk. To better understand the GERPOHR method is beneficial for rockburst mitigation. In this paper, the design of GERPOHR was first introduced. And the layout of the working face was optimized. Then, based on the numerical simulation, the stress and displacement distribution characteristics were compared under the condition of conventional mining and GERPOHR method. The research shows that the intervals of main roof weighting could be decreased through the precut overhanging hard roof method. And the peak value of abutment pressure decreased. Meanwhile, the energy accumulation and the stress fluctuation could be alleviated in roadway surrounding rock.

China has over 1500 open-pit mines and 5000 dumps consisting of waste rock from the mining process. Due to dump instability in an open-pit mine and its diverse foundations, landslides and mudslides frequently occur. Heaped loose waste rock and concentrated heavy rainfalls are the two important factors affecting slope stability of a dump. Using the high Dump II within the Nanfen Open-Pit Iron Mine with a slope height of 300 m as a case study, this paper first proposes a physical model similarity ratio according to the on-site engineering geological survey data. The governing principles of deformation in the shallow dump layers in terms of different heaped loads and rainfall were then determined using fiber optic sensing to conduct an experimental study on the monitoring of the dump stability with an indoor physical model. Experimental results confirm that the amount of rainfall and heaped load has a great impact on the landslide in a dump. With an increase in the amount of material heaped onto the pile, the place between two heaped load points is squeezed and slowly deformed. As rainfall begins, the deformation of the rock-soil mass is significant, and constantly increasing rainfall intensity is accompanied by a dangerous sliding surface. Finally, the FLAC3D method was used to simulate the deformation features in the shallow part of Dump II under different heaped load conditions and verify the experimental results of the indoor physical model. By comparing the physical model experiments and numerical simulation results, we propose monitoring the stability of Dump II using this fiber optic sensing technology and provide the scientific basis for stability monitoring of similar dumps to detect the early warning signs of mudslides or landslides.