Mining Hazards to the Safety of Segment Lining for Tunnel Boring Machine Inclined Tunnels

The segment lining is a new type of support structure for mining tunnels. The disturbance of coal excavation leads to the deformation of segment lining and has great hazards to the safety of the tunnels. Based on the tunnel boring machine (TBM) inclined tunnels in Xinjie mine, the ultimate span L0 of the rock beam on the top slab of the coal seam was calculated according to the bending (tension) damage theory. A numerical model was built to simulate the bottom area of the inclined tunnels. During the coal mining, the additional displacements and additional stresses of the segment lining were analyzed, and then the safety factors of the support structure were calculated. Finally, the width of the coal pillar to protect the inclined tunnels was determined. The results showed that the ultimate span of the rock beam on the top of the coal seam is 31.7 m, the deformation of the inclined tunnel has a fish-belly shape, and the deformation leads to the increase of maximum axial force and bending moment. For the inclined tunnels in Xinjie coalmine, a total width of 91.3 m of coal pillar must be reserved to keep the safety factor of the structure higher than 2.0 and prevent the inclined tunnels from the mining hazards.

Analysis of orthogonal signal of dual-mass micro-machined gyroscope

The dual-mass Silicon micro-machined gyroscope was processed by micro-fabrication technology. It could lead to quadrature coupling error and influence the output of the silicon micro-gyroscope. We select two commonly used gyroscope structures and analyze their quadrature coupling coefficient. Firstly, the complete dynamic model is proposed for the DMSG and the theoretical models of sensitivity and orthogonal signals are given by the dynamic model. Second, the influence of support structure on sensitivity and orthogonal signals are analyzed. The sensitivity and orthogonal signal of the two types of DMSG are derived and compared. The results show that the theoretical accuracy of the sensitivity and orthogonal signals can be improved about 50% and 30% after considering the support structure. The type-B gyroscope are insensitive to the Coriolis force (≈13% reduction) when compared to Type-A gyroscope. On the other hand the type-B gyroscope are insensitive to coupling stiffness (≈85% reduction) when compared to Type-A gyroscope. At last, the reliability of the theory is verified by simulations and experiments.

Creating Educational Robots

After more than 30 years of development, the designing, constructing, and programming of educational robots is still enjoying increasing popularity in formal, non-formal, and informal educational settings. Although building instructions and required technical components are easily available and accessible, the realization of own teaching projects is a special challenge and is subject to decisive influences. This includes the content-related training of teachers as well as their attitudes and ways of thinking and acting. Therefore, the first section of this chapter spans an arc from the didactic concept of the extracurricular project technikcamps related to robotics. The experiences gained from it and the consequences for teacher training to the philosophical roots of technical education follows. In connection with this, the main part deals with the technological basics of creating educational robots in general. It leads from manufacturing single parts through the creation of a support structure and automation to the application of the engineering design process.

Investigation of Deep Shaft-Surrounding Rock Support Technology Based on a Post-Peak Strain-Softening Model of Rock Mass

To control the large deformation that occurs in deep shaft-surrounding rock, the post-peak strain-softening characteristics of deep jointed rock mass are discussed in detail. An equivalent post-peak strain-softening model of jointed rock mass is established based on continuum theory and the geological strength index surrounding rock grading system, and numerical simulations are performed using FLAC3D software. The convergence-constraint method is used to analyze the rock support structure interaction mechanism. A composiste support technique is proposed in combination with actual field breakage conditions. During the initial support stage, high-strength anchors are used to release the rock stress, and high-stiffness secondary support is provided by well rings and poured concrete. This support technology is applied in the accessory well of a coal mine in Niaoshan, Heilongjiang, China. The stability of the surrounding rock support structure is calculated and analyzed by comparing the ideal elastic-plastic model and equivalent jointed rock mass strain-softening model. The results show that a support structure designed based on the ideal elastic-plastic model cannot meet the stability requirements of the surrounding rock and that radial deformation of the surrounding rock reaches 300 mm. The support structure designed based on the equivalent joint strain-softening model has a convergence rate of surrounding rock deformation of less than 1 mm/d after 35 days of application. The surrounding rock deformation is finally controlled at 140 mm, indicating successful application of the support technology.

Geometrical Tests of Powered Roof Support Positioning in a Longwall Complex

A powered roof support protects people and equipment in the longwall from potential dangerposed by the surrounding rock mass. The study to determine the position of the powered roof supportwas conducted in an active longwall. The research team made measurements of the geometric height ofthe powered roof support structure located in the longwall complex. The main objective of this studywas to determine the position of the powered roof support in actual underground conditions. Theanalysis of the results provided data on whether the assumed height of the longwall was maintainedduring operation of the complex.