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In order to solve the problems of low efficiency, multiple blind spots, and high risks in traditional debris flow exploration, two technical means were adopted: small baseline subset interferometric synthetic aperture radar (SBAS-InSAR) and unmanned aerial vehicle (UAV) low altitude remote sensing (the former obtains highly reliable deformation of vegetation coverage areas through dense images, while the latter obtains high-resolution realistic 3D models through regional network adjustment and other processing) . Integrating deformation and image texture, a survey and analysis of debris flow valleys along a railway in a certain mountainous area was conducted to obtain the spatial and temporal distribution of geological hazards in the watershed. The results show that, through SBAS-InSAR technology, it was found that there were multiple seasonal active hazards in the debris flow valley, with a maximum deformation variable of 28.5 mm/a. Based on the 3D model of UAV, a detailed investigation was conducted on the spatial form, volume, occurrence, and development of the deformation hazard. The largest scale landslide had a volume of 165 000 to 180 000 cubic meters. On site investigations show that the comprehensive remote sensing technology can effectively overcome the challenges of complex mountainous terrain and difficult access for humans, providing a multidimensional perspective for disaster screening. It has the advantages of low personnel investment, wide monitoring area, fast disaster positioning, and high screening accuracy. [ABSTRACT FROM AUTHOR]

To evaluate the tunneling effect of the earth pressure balance(EPB) shield in typical strata in Nanchang, China, a case study is conducted on a shield tunnel from Shengjinta station to Liuyanjing station. The evolution patterns of the main tunneling parameters of the EPB shield in full-section gravel sandstone stratum, full-section argillaceous siltstone, and composite sand-rock strata are investigated. Then, some characteristic parameters of the stratigraphic boreability including penetration degree, field penetration index, and tunneling specific energy are introduced to establish the relationships between the investigated key tunneling parameters. On this basis, the stratigraphic boreability of these three types of strata is evaluated. The research results indicate the following: (1) The main tunneling parameters are stable relatively when tunneling in gravel sandstone and argillaceous siltstone strata. The total thrust and the rotation speed of the cutterhead increase considerably in the composite sand-rock strata. (2) The cutterhead torque decreases gradually when shield tunnels from composite sand-rock strata to argillaceous siltstone strata. There is a satisfied positive linear relationship between the cutterhead torque and the total thrust in the argillaceous siltstone strata. (3) The value and oscillation of the penetration degree decline obviously when the shield tunnels from gravel sandstone to argillaceous siltstone strata. There are similar distributed characteristics of the field penetration index in the composite sand-rock strata and argillaceous siltstone strata but exhibit an opposite variation trend. Nevertheless, the tunneling specific energies of shield in these three strata are close to each other. (4) Significant correlations between the field penetration index and the penetration degree are observed in both gravel sandstone and composite sand-rock strata, but the correlation is weak in argillaceous siltstone strata. (5) The shield has a highest penetration degree and lowest field penetration index and tunneling specific energy in gravel sandstone strata, indicating the best tunneling effect of EPB shield in such strata. (6) On the whole, the gravel sandstone strata and the intermediately-weathered argillaceous siltstone strata show a better boreability than composite sand-rock strata. [ABSTRACT FROM AUTHOR]

Bulk hydrophobic SiO2 aerogels were synthesized via sol-gel method by ambient pressure drying with methyltrimethoxysilane as precursor and methanol as solvent. A super-hydrophobic cotton fabric was prepared by coating the mixture of SiO2 aerogel and PDMS (polydimethylsiloxane) onto cotton fabric. The effects of different conditions on the gelation time, density and porosity were discussed, and the optimum process was obtained. The surface morphology and wetting properties of the SiO2 aerogel and coated cotton fabric were studied by field emission scanning electron microscopy and contact angle measurement. The water contact angle of the prepared bulk SiO2 aerogels was 151.0°, which achieved super-hydrophobic effect and had three-dimensional continuous porous microstructure. The contact angle of cotton fabric treated with PDMS/SiO2 aerogel mixture was 155.4°. And the surface of the treated cotton fabric was covered with a large amount of SiO2 aerogels. The super-hydrophobic effect was achieved by the synergy between low surface energy characteristic of PDMS and the three-dimensional network micro-rough structure of SiO2 aerogels, and the crosslinking of aerogels and textile by PDMS. [ABSTRACT FROM AUTHOR]