Research on the control of overburden deformation by filling ratio of cementing filling method with continuous mining and continuous backfilling.

Underground resource exploitation has seriously damaged the surface ecological environment and underground water system. As an effective control measure, the filling mining process has greatly reduced the surface subsidence. As a branch of the filling mining process, the continuous mining and continuous backfilling (CMCB) method solves the contradiction of mining and filling in this process. The control index of filling ratio of even number lane (FRE) was presented to investigate the technical advantages of the CMCB method. The numerical analysis model was used to investigate the laws such as deformation characteristics of the surrounding rock, stress distribution, and plastic area distribution characteristics of backfill under four typical cases. As a consequence, the FRE effect law on overburden deformation and the roof control function of the backfill was disclosed, and overburden rock deformation control solutions were provided. According to the results, the overburden deformation varies dramatically when the FRE decreases, and it rises greatly when the even-numbered lane backfill (ELB) is not contacted with the roof. The contacting condition and filling condition of the odd numbered lane backfill (OLB) are connected to the distribution of stress and plastic zone. The backfill transmits the rock beam load by building a composite support system with the roof and floor rock layers, and it accomplishes the backfill's roof control function by combining the primary and secondary load-bearing and synergistic load-bearing connections between the backfills. Measures such as differential FRE, differential strength, non-uniformity of filling lane, and synergistic bearing of temporary support and backfill may help to decrease deformations and internal cracks in the surrounding rock. This measure has been successfully implemented in the field, serving as an experience for the application of the CMCB method.

An in situ simultaneous measurement system combining photoelasticity and caustics methods for blast-induced dynamic fracture.

Photoelasticity and caustics methods are extensively used in the history of dynamic fracture mechanics. However, there is little work for the combination of them in the same experiment associated with high loading rate in extreme conditions. In the present work, it is the first time to build a simultaneous measurement system which can use photoelasticity and caustics methods at the same instant for in situ optical investigations of blast-induced dynamic fracture. To illustrate the capability of this system, an explosion experiment using a 2D epoxy plate is conducted, yielding consistent results between two methods. This novel system provides rich experimental data including local-field information for the crack tip and full-field information for blasting waves.

Preparation and adsorption properties of crosslinked polystyrene-supported low-generation diethanolamine-typed dendrimer for metal ions.

Two novel chelating resins, polystyrene supported G1.0 diethanolamine-typed dendrimer (PS-DEA) and G2.0 diethanolamine-typed dendrimer (PS-(DEA)(2)), were prepared by anchoring low-generations diethanolamine-typed dendrimer into crosslinked polystyrene in this paper. Fourier transform-infrared spectra (FTIR), scanning electron microscopy (SEM) and elemental analysis were employed to character their structures. The results of adsorption for metal ions showed that the resins had good adsorption capacities for Cu(2+), Ag(+) and Hg(2+), especially PS-DEA for Cu(2+). The adsorption kinetics and adsorption isotherms of PS-DEA for Cu(2+) and PS-(DEA)(2) for Hg(2+) were studied. The results showed that the adsorption kinetics of the two resins can be modeled by pseudo second-order rate equation wonderfully and Langmuir and Freundlich equations could well interpret the adsorption of PS-(DEA)(2) for Hg(2+) and PS-DEA for Cu(2+), respectively. The adsorption mechanism of the resins for Cu(2+) was confirmed by X-ray photoelectron spectroscopy (XPS).