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In view of the problem that the water gushing problem of deep coal mine roadway seriously affects the safety of coal mine construction, and the common cement grout is difficult to seal up the tiny rock cracks, the micron-grade fly ash is used to replace part of superfine cement, polycarboxylate superplasticizer and nano-CaCO3 admixture are used to improve the performance of composite slurry. The results show that the slurry properties vary with the water-cement ratio, and are negatively correlated with the initial viscosity, hardened rate and strength, while positively correlated with fluidity. The appropriate addition of nano-CaCO3 made the strength slightly improved, but the viscosity, fluidity and hardened rate did not change significantly. The addition of micron-grade fly ash reduces the viscosity, hardened rate and strength, and appropriately improves the fluidity. The polycarboxylate superplasticizer was positively correlated with fluidity and negatively correlated with stone rate, but had little effect on viscosity and strength. The change of slurry viscosity with time can be divided into two stages: stable period and rising period. The viscosity change rate of stable period does not exceed 15.5%.

The problem of water seepage through sandstone micro-fractures in deep well is one of key factors influencing normal production. With the method of single factor sensitivity analysis, this paper is to tell us how to affect the seepage of micro-fractures by roughness, fracture opening, confining pressure and seepage pressure by self-developed micro-fracture triaxial stress seepage mechanism model test system. Simultaneously, numerical simulation is used to study the seepage process of micro-fractures in sandstone, and explain the evolution process of hydraulic fracture under water pressure. The results show that the factors that affect the seepage of micro-fractures from strong to weak are osmotic pressure, roughness, fracture opening and confining pressure; the evolution process of hydraulic fracture propagation under water pressure can be divided into the stress accumulation stage and the stable expansion stage of micro-fractures.

It has been claimed in the linguistic literature that numeral classifiers in some Sinitic languages are functionally equivalent to the definite article in the English language, based on the observation that bare classifiers or [Cl+N] expressions can be interpreted as definite under some circumstances. Based on our fieldwork on several Southern dialects in Mainland China, such as Wu, Xiang, Min and Yue dialect, and the evolutionary process of Chinese numeral classifiers, it has been found that (i) the alleged "definiteness" is actually not the inherent property of numeral classifiers themselves, but is expressed via the pragmatic contexts; (ii) [Cl+N] expressions or bare classifiers have nothing to do with "definiteness" out of context, and if placed in a certain context, can be stochastically understood as either definite or indefinite, (iii) it is certainly wrong to ascribe "definiteness" to a certain linguistic element such as "classifier", "nominal" or even "numeral" when a bare classifier, a bare nominal, a [Cl+N] or a [Numeral +Cl+N] expression is construed as definite in a communicative context, since they constitute an essentially pragmatic phenomenon. [ABSTRACT FROM AUTHOR]