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This study aims to analyze the dynamic response characteristics of the serviced asphalt pavement subjected to the real random vehicle loads. Fiber Bragg Grating (FBG) sensors were embedded within four types of asphalt pavements to establish pavement structural information monitoring system. Then the spatial-temporal distribution of dynamic response were obtained by data analysis. The influences of speed, axle load and temperature on the pavement response as well as the response comparison among four types of asphalt pavements were investigated. The results show that low speed, large axle load and high temperature may cause large pavement damage. The order of strain response magnitude at the bottom of asphalt layer is: Structure II > Structure III > Structure I > Structure IV. FBG measuring technology is quite reliable and beneficial for dynamic response monitoring and performance evaluation of the asphalt pavement.

Overlying key strata are regarded as plane-strained beams sandwiched by the soft rock strata in the up and down directions, and are considered elastic media. Based on the theory of the elastic foundation beam, the distribution of energy accumulation and fracture positions before and after the fracture of overlying key strata are derived, and the energy release of fractures in each stratum is calculated. To investigate the impact damage to a roadway owing to the breaking of the key stratum, panel 5312 of Jining No. 3 coal mine is taken as an example. FLAC 3D software was applied to simulate a rock burst on the roadway when the seismic source was located at the overlying key strata and different energy was released. It is shown that the side of the roadway near the working face had a high concentration of vertical stress in the coal, and the dynamic load increment generated by the source broke the static load state and triggered the rock burst. After the burst damage, the decrease in the vertical stress in the coal explained the source of the kinetic energy. With a horizontal deformation velocity of the roadway’s surrounding rocks of 1.5 m/s as the limit, the critical energy value for the burst failure caused by the fracture of each key stratum was determined.

With the dramatic increase of air traffic volume and the rapid development of civil aviation airport construction in China, asphalt layers overlaying original concrete pavement in civil aviation airports has become the primary rehabilitation scheme. However, asphalt airport pavement is prone to excessive deformation when subjected to the repeated and heavy aircraft loading, especially when coupled with high-temperature field. However, the impact of high-temperature jet wake is rarely considered in the existing structural design and analysis of airport asphalt pavement. In order to investigate the impact of high-temperature jet wake on the dynamic response of asphalt pavement, the coupling of finite element (FE) simulation of the temperature field and aircraft loading based on sequential decoupling methodology was implemented herein. Firstly, the temperature field distribution induced by the high-temperature jet wake on the asphalt pavement was simulated and analyzed by FE simulation on the ABAQUS CFD platform. Then, the temperature field distribution was integrated within the asphalt pavement structure by combining the temperature field distribution produced by jet wake and thermal conduction between ambient radiation and pavement. Secondly, the viscoelastic parameters of each asphalt layer under the obtained temperature field distribution were calculated to represent more real material properties. Finally, FE simulation of airport asphalt pavement subjected to the coupling of aircraft loading and integrated temperature field was conducted. The results show that the amplitudes of transverse strain, vertical strain, and longitudinal strain of the asphalt pavement considering jet wake together with ambient radiation are basically higher than those without consideration. Consequently, the dynamic responses of airport asphalt pavement produced by jet wake and ambient radiation should be fully considered in the design and analysis of airport asphalt pavement.

Because of the limitation of mining techniques and economic conditions, large amounts of residual coal resources have been left in underground coal mines around the world. Currently, with mining technology gradually developing, residual coal can possibly be remined. However, when residual coal is remined, caving areas might form, which can seriously affect the safety of coal mining. Hence, grouting technology is put forward as one of the most effective technologies to solve this problem. To study the grouting diffusion in fractured rock mass, this paper developed a visualization platform of grouting diffusion and a three-dimensional grouting experimental system that can monitor the grout diffusion range, diffusion time and grout pressure, then, a grouting experiment is conducted based on this system. After that, the pattern of the grouting pressure variation, grout flow and grout diffusion surface are analyzed. The relationship among some factors, such as the grouting diffusion radius, compressive strength of the grouted gravel, porosity, water-cement ratio, grouting pressure, grouting time, permeability coefficient and level of grout, is quantitatively analyzed by using MATLAB. The study results show that the flow pattern of the grout in fractured porous rock mass has a parabolic shape from the grouting hole to the bottom. The lower the level is, the larger the diffusion range of the grout is. The grouting pressure has the greatest influence on the grouting diffusion radius, followed by the grouting horizon and water-cement ratio. The grouting permeability coefficient has the least influence on the grouting diffusion radius. The grout water-cement ratio has the greatest influence on the strength of the grouted gravel, followed by the grouting permeability. The grouting pressure coefficient has the least amount of influence on the grouting diffusion radius. According to the results, the grouting parameters are designed, and a layered progressive grouting method is proposed. Finally, borehole observation and a core mechanical property test are conducted to verify the application effect. This grouting technology can contribute to the redevelopment and efficient utilization of wasted underground coal resources.

A method of slope reliability analysis was developed by imposing a state equation on the limit equilibrium theory, given the basis of a fixed safety factor technique. Among the many problems of reliability analysis, the most important problem is to find a performance function. We have created a new method of building a limit state equation for planar slip surfaces by applying the mathematical cusp catastrophe theory. This new technique overcomes the defects in the traditional rigid limit equilibrium theory and offers a new way for studying the reliability problem of planar slip surfaces. Consequently, we applied the technique to a case of an open-pit mine and compared our results with that of the traditional approach. From the results we conclude that both methods are essentially consistent, but the reliability index calculated by the traditional model is lower than that from the catastrophic model. The catastrophe model takes into consideration two possible situations of a slope being in the limit equilibrium condition, i.e., it may or may not slip. In the traditional method, however, a slope is definitely considered as slipping when it meets the condition of a limit equilibrium. We conclude that the catastrophe model has more actual and instructive importance compared to the traditional model.

Coal burst and mine earthquake frequently occur with high strength in impact roadway. Bolting system will produce a certain dynamic response under the impact load disturbance. Bolts will be damaged and rock will be instability when it serious. How to design bolting system in impact roadway is a major technical problem that has not been solved. This paper analyzes the dynamic response of bolt supporting in impact and mechanized caving roadway by FLAC3D.Then it gets the bolt axial force, shear stress of anchor agent and deformation of roadway variation with time and space. This study provides the design basis for the optimizing impact roadway bolting and improves control effect of bolting system. The results show that under the impact load the degree of dynamic response of anchor and roadway has great relationship with the distance between the measuring point and the power source. It reflects sensitively. Tilt bolts affect greatly. Threads and components of bolt tail are easily damaged, while anchoring agent prone to shear failure. Therefore, the bolt of rock burst roadway should have high prestress and high strength. While the choice of bolt end member, anchoring agent, the let press member and bolt elongation with high energy absorption properties are also very important.