Abstract
In this study, 16 groups of tests were designed by the orthogonal test method, and a PU grouting material was prepared, which can be used for the construction of sealing wall in mined-out area of coal mine. The basic properties of the material were measured. Firstly, the viscosity of four groups of samples with different polyether polyol contents was measured by a dynamic rheometer. Secondly, the uniaxial compressive strength of pure slurry samples and sand-containing samples was measured by a universal testing machine. Finally, the failure process of sand-containing samples was monitored by acoustic emission equipment. Through the above research and analysis, a PU grouting material with excellent performance has been obtained. That is, when the ratio of polyether triol:polyether tetraol:catalyst:surfactant:chain extender:plasticizer is 11 : 9 : 0.5 : 1.0 : 1.2 : 6.0, PU grouting material has higher injectability and ideal compressive strength, which has been proved in grouting experiments.
Highlights
In recent years, with the development and application of polymer grouting materials and the development of grouting material production technology, polymer grouting materials have been widely used in my country
Acoustic emission technology was used to monitor the whole process of sand-containing specimens from initial crack generation to final failure. e material prepared in this paper has low viscosity and considerable strength and deformation. e airtight wall has a certain deformation ability, which can coordinate with the deformation of the roof rock beam and the surrounding coal rock, fully absorb the deformation of the roof rock beam and the surrounding rock in the broken area transferred to the airtight wall, and prevent the airtight wall in the goaf from being damaged due to overload
Aiming at the problem of crack or fracture in goaf under mining stress, PU filling material with certain strength was prepared in this study, and its basic properties such as viscosity, foaming ratio, and compressive strength were measured. e generation and propagation of crack were monitored by acoustic emission equipment, and the following conclusions were obtained: (1) e gel time, curing time, expansion ratio, and other properties of the prepared polyurethane grouting material can be adjusted according to specific needs
Summary
With the development and application of polymer grouting materials and the development of grouting material production technology, polymer grouting materials have been widely used in my country. Ey are used in coal mining face to help control, fill large caving spaces, and quickly seal fissure water. Acoustic emission technology is mainly used for failure process and damage assessment of specimens under compression conditions [31, 32]. E PU grouting material filling body prepared in this paper had low strength, good deformation, and certain bearing capacity and could be applied to the construction of sealing wall in goaf. In this article, based on the requirements of plugging and strengthening the sealing wall in the mined-out area of coal mine, we prepared a two-component PU grouting material and measured the performance indexes such as viscosity, gel time, expansion ratio, compressive strength, etc. Erefore, the grouting reinforcement test was carried out on the prepared grouting material, and the compressive strength of the sand-containing specimens was tested. Acoustic emission technology was used to monitor the whole process of sand-containing specimens from initial crack generation to final failure. e material prepared in this paper has low viscosity and considerable strength and deformation. e airtight wall has a certain deformation ability, which can coordinate with the deformation of the roof rock beam and the surrounding coal rock, fully absorb the deformation of the roof rock beam and the surrounding rock in the broken area transferred to the airtight wall, and prevent the airtight wall in the goaf from being damaged due to overload
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