Field Study on the Law of Surface Subsidence in the High-Intensity Fully Mechanized Caving Mining Working Face with Shallow Thick Bedrock and Thin Epipedon in Hilly Areas

Shallow and thick coal seams occur extensively in hilly areas in Shanxi Province and Shaanxi Province, China. The surface damage and landslides caused by shallow fully mechanized caving mining have a very serious impact on the environment. To provide a theoretical and reference foundation for mine environmental protection in hilly settings, a research on surface movement of the high-intensity fully mechanized caving mining working face with shallow thick bedrock and thin epipedon (HIFMCMWFSTBTE) is urgently needed. In this study, using the P2 working face of a mine as the research object, three surface subsidence observation lines were arranged in this working face to analyze the dynamic change characteristics of surface subsidence. Besides, the law of surface movement, mining sufficiency, fracture development and distribution characteristics, subsidence speed, and surface movement duration of HIFMCMWFSTBTE in hilly areas were comparatively studied. The research results reveal that the upper part of the slope slides towards the downhill direction under the action of tensile stress or push stress. As a result, the range of the horizontal movement towards the downhill direction of the slope and the range of surface movement both increase, and the movement angle and boundary angle both decrease compared with the plain. HIFMCMWFSTBTE is prone to serious sudden discontinuous damage. Fractures on the gully region surface develop along the contour, forming a crisscross fracture network, and the fractures are not easy to close after being generated. HIFMCMWFSTBTE in hilly areas can achieve full mining more easily than those of other geological conditions. According to the field measurement, critical full mining can be achieved in P2 working face when the ratio of mining width to mining depth is 1.07. The surface movement duration of HIFMCMWFSTBTE in hilly areas is relatively short. Considerable subsidence will occur in the active stage, and the surface subsidence is sudden and violent. The measured surface stabilization time of the P2 working face is only 20% of the calculated value in the Specification for Coal Pillar Reservation and Coal Mining under Buildings, Water Bodies, Railways, and Main Shafts (hereinafter referred to as the Specification), indicating that the specification's empirical formula is inapplicable to the calculation of surface stabilization time of the P2 working face.

Live-Cell Imaging of Single Neurotrophin Receptor Molecules on Human Neurons in Alzheimer’s Disease

Neurotrophin receptors such as the tropomyosin receptor kinase A receptor (TrkA) and the low-affinity binding p75 neurotrophin receptor p75NTR play a critical role in neuronal survival and their functions are altered in Alzheimer’s disease (AD). Changes in the dynamics of receptors on the plasma membrane are essential to receptor function. However, whether receptor dynamics are affected in different pathophysiological conditions is unexplored. Using live-cell single-molecule imaging, we examined the surface trafficking of TrkA and p75NTR molecules on live neurons that were derived from human-induced pluripotent stem cells (hiPSCs) of presenilin 1 (PSEN1) mutant familial AD (fAD) patients and non-demented control subjects. Our results show that the surface movement of TrkA and p75NTR and the activation of TrkA- and p75NTR-related phosphoinositide-3-kinase (PI3K)/serine/threonine-protein kinase (AKT) signaling pathways are altered in neurons that are derived from patients suffering from fAD compared to controls. These results provide evidence for altered surface movement of receptors in AD and highlight the importance of investigating receptor dynamics in disease conditions. Uncovering these mechanisms might enable novel therapies for AD.

Numerical Simulation Study of the Strata Movement Rule of Deep Mining with the Super-Thick and Weak Cementation Overburden: A Case Study in China

As the national energy strategy is to mine westward, the deep coal resources under the super-thick and weak cementation overburden in the western mining area will play a critical role in China’s sustainable economic growth. The super-thick and weak cementation overburden has weaker lithology, thicker strata, no large joints, bedding development, and better integrity. Therefore, its movement rule is inevitably different from that of the weak overburden and the middle hard overburden in Central China and Eastern China. However, lack of studies on the movement of the super-thick and weak cementation overburden has led to severe constraints for the large-scale exploitation of coal resources under the super-thick and weak cementation overburden in the western mining area. This study explored the surface movement rule and the influence of overburden characteristics on strata movement with field measurement and numerical simulation. The findings indicate that the surface reaches full mining and the subsidence coefficient is about 0.9 when D1 (width in the dip direction) and D3 (length in the strike direction) are 3 times H0 (the mean mining depth) or more. The strike mining degree has a certain influence on the surface movement law, the maximum difference of the surface subsidence coefficient is 0.35, and the maximum difference of the horizontal movement coefficient is 0.05. In addition, the control effect of the Zhidan group sandstone is stronger. Thus, its first breaking results in surface sinking in a fractured manner when D1 is about 1.3 times H0 and D3 is 3 times H0 or more. The above results can provide reference for the safe mining and control of the super-thick weak cementation overburden.

Persistent Scatterer Interferometry for Pettimudi (India) Landslide Monitoring using Sentinel-1A Images

The continuous monitoring of land surface movement over time is of paramount importance for assessing landslide triggering factors and mitigating landslide hazards. This research focuses on measuring horizontal and vertical surface displacement due to a devastating landslide event in the west-facing slope of the Rajamala Hills, induced by intense rainfall. The landslide occurred in Pettimudi, a tea-plantation village of the Idukki district in Kerala, India, on August 6–7, 2020. The persistent-scatterer synthetic aperture radar interferometry (PSInSAR ) technique, along with the Stanford Method for Persistent Scatterers (StaMPS), was applied to investigate the land surface movement over time. A stack of 20 Sentinel-1A single-look complex images (19 interferograms) acquired in descending passes was used for PSInSAR processing. The line-of-sight (LOS ) displacement in long time series, and hence the average LOS velocity, was measured at each measurement-point location. The mean LOS velocity was decomposed into horizontal east–west (EW ) and vertical up–down velocity components. The results show that the mean LOS, EW, and up–down velocities in the study area, respectively, range from –18.76 to +11.88, –10.95 to +6.93, and –15.05 to +9.53 mm/y, and the LOS displacement ranges from –19.60 to +19.59 mm. The displacement values clearly indicate the instability of the terrain. The time-series LOS displacement trends derived from the applied PSInSAR technique are very useful for providing valuable inputs for disaster management and the development of disaster early-warning systems for the benefit of local residents.

Ground Subsidence Evolution from 1000 m Deep Mining: A Case Study in Fengfeng Mining Area

The mining of coal resources in eastern China has entered the stage of deep mining, and many mines have reached the depth of 1000 meters. Different from shallow and moderate depth mining, the temporal and spatial evolution regulation of surface movement and deformation under deep mining has its particularity. Combining with the geological and mining conditions of Fengfeng mining area, this paper systematically studies the characteristics of surface movement under the condition of shallow, moderate, and near kilometer mining depth. By means of field measurement, InSAR monitoring, we get the subsidence data under different mining depth and get the relevant subsidence parameters by inversion. Through comparative analysis, the special law of subsidence under the mining depth of 1000 meters is obtained. The results show that under the condition of nearly 1000 meters mining depth, the surface movement and deformation have the characteristics of large displacement angle, small displacement deformation value, and large main influence radius. The regulation of small proportion of active period of maximum subsidence point, gentle shape of surface movement basin, and low mining adequacy are obtained. The research results provide technical references for deep mining under buildings, railways, and water bodies and provide basis and reference for scientific mining and safe recovery of coal pillars in kilometer deep mine.

Single-Molecule Imaging Reveals Rapid Estradiol Action on the Surface Movement of AMPA Receptors in Live Neurons

Gonadal steroid 17β-estradiol (E2) exerts rapid, non-genomic effects on neurons and strictly regulates learning and memory through altering glutamatergic neurotransmission and synaptic plasticity. However, its non-genomic effects on AMPARs are not well understood. Here, we analyzed the rapid effect of E2 on AMPARs using single-molecule tracking and super-resolution imaging techniques. We found that E2 rapidly decreased the surface movement of AMPAR via membrane G protein-coupled estrogen receptor 1 (GPER1) in neurites in a dose-dependent manner. The cortical actin network played a pivotal role in the GPER1 mediated effects of E2 on the surface mobility of AMPAR. E2 also decreased the surface movement of AMPAR both in synaptic and extrasynaptic regions on neurites and increased the synaptic dwell time of AMPARs. Our results provide evidence for understanding E2 action on neuronal plasticity and glutamatergic neurotransmission at the molecular level.

Numerical Simulation of Surface Movement and Deformation Caused by Underground Mining with Complex Stratigraphic Boundary

The interface program of finite element software based on surface spline interpolation is developed by using MATLAB software. The controllable 3D surface modeling based on CAD contour is realized. Taking a mine as an example, the method of establishing the 3D numerical calculation model including complex stratum boundary is studied. The influence of underground mining on surface movement and deformation under complex stratum conditions by using the FLAC3D software further was discussed. The research results show that the developed interface program of finite element software can well realize the numerical modeling of complex formation and provide help for subsequent numerical simulation. The calculated subsidence value is in good agreement with the measured value. The values of surface tilt, surface curvature, and surface horizontal deformation are less than the relevant regulations. The mining method of the filling method has no obvious effect on the surface structures. The research results can provide reference for similar numerical simulation.