Study On The Loads And Design Theory Of The Monolayer Freezing Shaft Lining In Water-rich Bedrock

Based on the characteristic and conditions of sinking shaft by freezing method in pore water-bearing rock strata, the research on the stress regulation of monolayer freezing shaft lining in water-bearing bedrock was carried out through theoretical analysis, numerical analysis, physical simulation experiment and field measurement. The design theory and calculation methods were put forward for the monolayer freezing shaft lining in water-rich bedrock, as well as the calculation formula.Firstly, according to the stress characteristics of the monolayer shaft lining in the bedrock during the frozen wall thawing period and production period, a relatively practical mechanical model of monolayer freezing shaft lining in the bedrock was established to conduct the analytical analysis research. And consequently, some research results were obtained including the strict stress analytical solutions of shaft lining and surrounding rock, the analytical solutions of the shaft lining with radial load and interaction force between shaft lining and the surrounding rock applied and the change rules of interaction force.Secondly, on the basis of the construction process of the shaft lining, a relatively practical numerical model was established to analyze the stress regulation of the monolayer freezing shaft lining in the bedrock. In addition, the numerical solutions of the shaft lining were also obtained with radial load and interaction force applied. Contrast analysis shows that analytical solutions are consistent with numerical solutions, indicating that the analytical solutions are correct, which can be used to design the shaft lining. Under the conditions of water-bearing surrounding rock, its elastic modulus, porosity and Poisson's ratio greatly influence the shaft lining stress and the characteristics of contact surfaces between shaft lining and surrounding rock. Therefore, for the pore water-bearing surrounding rock, the different values of physical and mechanical parameters in ex- frozen and post-frozen period need to be paid great attention.Thirdly, the physical simulation study was carried out on the interaction between the shaft lining and pore rock. First, a kind of similar material of porous rock was prepared with the orthogonal test method, which was made of coarse sand, permeable concrete strength additive, cement and water. And its five similarity coefficient is approximately equal to 1. At the same time, the similar material of shaft lining was prepared using epoxy anchorage adhesive. Then, using the simulation model made by with the similar materials, a large-scale simulation experiment was conducted on the characteristics of porous rock and shaft lining with water pressure loaded under water-bearing conditions. And the stress regulation of the shaft lining was obtained with the pore water pressure applied. The experimental studies have shown: when certain compressive stress exist in the interfaces between the shaft lining and the surrounding rock, the stress regulation of the shaft lining can be divided into two stages during the pore water pressure loading. In the first stage, the shaft lining strain in the inner edge remains unchanged or slightly increases before the pore water pressure increases to a certain value; when exceeding this value, the shaft lining strain in the inner edge changes linearly with the pore pressure.Fourthly, aiming at the monolayer freezing shat lining in the bedrock, the field measurement was conducted to monitor the stress on the air shaft in Ma Tai-Hao coal mine, Ordos, Inner Mongolia. The change rules of the concrete strain, reinforcement stress and the load was monitored during construction, thawing and operation period. The measurement studies have shown: the monitored shaft lining didn't separate from the surrounding rock, which was secure with small stress. The stress regulation of the shaft lining in ex-thaw and post-thaw period was consistent with the theoretical analysis.In the end, based on the above research results, the design theory and calculation methods were put forward for the monolayer freezing shaft lining in water-rich bedrock. The theory of the monolayer freezing shat lining in the bedrock been successfully applied in practical engineering.The paper have figure of 93, table 47, 173 references.