Study on risk assessment of tunnel construction across mined-out region based on combined weight-two-dimensional cloud model.

In this thesis, a risk assessment framework based on the Pressure-State-Response (PSR) model is proposed for the risk assessment problem of crossing the mined-out region in tunnel construction. The subjective weights of the indicators are determined by the G1 method, the objective weights are determined by the improved CRITIC method combined with the Random Forest (RF) machine learning method, and the combined weights are calculated using the game-theoretic combination assignment method. On this basis, a two-dimensional cloud model was constructed to merge the risk frequency and consequence degree to comprehensively assess tunnel construction's safety risk across the mined-out region.

Collaborative control technology and application of support and modification for soft-rock roadway in a kilometer-deep coal mine.

The soft-rock roadways in kilometer-deep coal mines are often damaged by large deformation and have to be periodically expanded and repaired, which seriously restricts the safe and efficient production of coal mines. A typical soft-rock roadway in a kilometer-deep coal mine is selected as the engineering, and the main reasons for roadway deformation are analyzed, and the ground stress and mechanical characteristics are obtained. The Flac numerical model, which can accurately reflect the deformation characteristics of surrounding rock in kilometer-deep soft-rock roadway, has been constructed, and the evolution laws of stress field and its damage mechanism have been analyzed with the vertical stress, vertical displacement and plastic zone.

Microstructural Evolution and Damage Mechanism of Water-Immersed Coal Based on Physicochemical Effects of Inorganic Minerals.

Coal seam water injection technology enables seam permeability enhancement and facilitates outburst risk reduction. This study investigated the microscale effects of water infiltration on coal and the evolution mechanisms of its mechanical properties. To this end, we systematically analyzed dynamic changes (such as mineral composition, pore structure, and mechanical performance) in coal soaked for various durations using X-ray diffraction, low-field nuclear magnetic resonance (NMR), and uniaxial compression testing.

Influence of Tectonically Deformed Coal-Based Activated Carbon and Its Surface Modification on Methane Adsorption.

A series of coal-based activated carbons (CACs) were synthesized from mylonitized fat coal, a type of tectonically deformed coal (TDC) and symbiotic primary structural coal (PSC), followed by oxidative modification. The pore structure, surface oxygen-containing functional groups, and their influence on methane adsorption by CAC as the simplified coal model were investigated by using low-temperature nitrogen adsorption, Fourier transform infrared spectroscopy, Boehm titration, and X-ray photoelectron spectroscopy. The results showed that tectonic deformation fostered smaller pores, particularly ultramicropores in TDC, dominating methane adsorption.

Feasibility for High-Temperature Graphitization of Deformed Meager Coal.

The flattening of nanoscale pores is a crucial step in the process of anthracite graphitization, which primarily occurs due to lithostatic pressure or tectonic stress. Anthracite, a highly metamorphosed form of carbonaceous material, is a primary component of artificial graphite, but its availability is limited in China. Therefore, it is necessary to investigate the graphitization of low metamorphic coal.

Synthesis of a Solid Superacid and Its Application in Flame-Retardant Poly(vinyl chloride) Material.

TiO/PO solid superacid was synthesized by using the precipitation immersion method and characterized by means of X-ray diffraction (XRD) and an energy-dispersive spectrometer; it was added into flexible poly(vinyl chloride) (PVC) composites as a flame retardant. The smoke suppression and flame retardance of TiO/PO accompanied by SbO were investigated through the limiting oxygen index (LOI), cone calorimetry test, and thermogravimetry analysis (TGA). The results indicated that the LOI value of PVC/SbO/(TiO/PO ) reached to 32.

Thermal Degradation and Flame Retardant Mechanism of the Rigid Polyurethane Foam Including Functionalized Graphene Oxide.

A flame retardant rigid polyurethane foam (RPUF) system containing functionalized graphene oxide (fGO), expandable graphite (EG), and dimethyl methyl phosphonate (DMMP) was prepared and investigated. The results show that the limiting oxygen index (LOI) of the flame-retardant-polyurethane-fGO (FRPU/fGO) composites reached 28.1% and UL-94 V-0 rating by adding only 0.

Folate-conjugated micelles and their folate-receptor-mediated endocytosis.

A folate-conjugated copolymer PEG-PLA-PLL/folate was synthesized and mixed with pure PEG-PLA-PLL and a fluorescent model drug mFITC to prepare folate-conjugated micelles. The distribution of micelles was studied on cancer-cell-bearing mice via frozen slicing. The results show that mFITC is successfully encapsulated into folate(+) and folate(-)micelles; PEG-PLA-PLL micelles the latter can be internalized by both HeLa and CHO cells without selectivity due to their cationic surface charges, while folate(+)micelles exhibit more preferential endocytosis by HeLa cells than by CHO cells.