Research On Safety Assessment And Hazard Control Technology Of Shaft Freezing Construction In Luohe Group Sandstone Stratum

With the increase of coal mining depth, the geological conditions of coal seam occurrence is complex, the mine construction faces many technical problems. Among them, the most typical is the wellbore through the deep rich water, weak sandstone and alluvium vertical shaft freeze design commonly used in the design parameter and experience in soft rock, especially in luohe group sandstone formation in the design of vertical shaft freezing is no longer applicable. Therefore, in this paper, based on his long shaft freezing a mine in shaanxi province construction, the indoor experiment and theoretical analysis, numerical simulation and field measurement, the method of combining the soft rock strata in the west the most profound and the most typical luohe group sandstone formation shaft freezing construction has carried on the system research, evaluation and hazard control technology has achieved a certain theoretical value and practical significance of innovative research results, mainly include:⑴The main influence factors shaft freezing construction risk in Luohe group sandstone stratum are analyzed. Based on the formation characteristics and physical and mechanical characteristics of in-depth analysis of the Luohe formation sandstone in Luohe group sandstone stratum, the freezing shaft construction in the process of risk classification, and puts forward some factors of engineering geology and hydrogeology, load and the effects of main risk formation technology from freezing in the construction process, to ensure that the can play a positive role in guiding shaft freezing engineering optimization design and safe and efficient construction.⑵The stability of shaft frozen wall in Luohe group sandstone stratum is analyzed. Taking the typical Luohe formation sandstone shaft freezing construction as the basis, the Luohe formation sandstone shaft freezing wall stability were studied, analyzed the calculation method of deformation of frozen wall under different conditions of vertical shaft, the curve is obtained by Shaanxi Binchang mine freezing shaft wall deformation and time; 2)Established the Luohe formation sandstone freeze regression wall thickness and the factors affecting the calculation formula is given, the margin of safety thickness of frozen wall under certain conditions relevant construction parameters. Combined with field data, to verify its accuracy.⑶The shaft freezing wall deformation in Luohe group sandstone stratum is analyzed with the finite element software. Through the simulation of the initial state of the Luohe formation sandstone formation of 30 d, 60 d,90d and 120 d frozen, and reveal the formation process of frozen wall; according to the 64 models, for different shaft excavation section, the freezing temperature and the thickness of the frozen wall under the condition of the large displacement of frozen wall is numerically analyzed. The results show that, the maximum displacement of frozen wall and shaft freezing temperature, height of excavation section and the thickness of the frozen wall is nonlinear, and then established the maximum radial displacement of frozen soil wall of multi factor formula, the calculation results with the Shaanxi Binchang mine freezing shaft wall deformation measurement results are basically the same, has a positive reference value for the similar areas the formation conditions of the frozen shaft.⑷The risk of shaft freezing construction is forecasted and analyzed in Luohe group sandstone stratum. Single point prediction model based on neural network basic principle of Luohe formation sandstone shaft freezing construction information is established, combined with the Shaanxi Binchang mine freezing shaft project of Luohe formation sandstone formation, the key parameters of shaft freezing construction risk of the project forecast, predict the measured result and field consistent, accurate prediction method, strong applicability, reliable reference basis for the reasonable construction scheme and parameters for freezing.⑸The shaft freezing construction safety evaluation model in Luohe group sandstone stratum is established. Based on the analysis of construction safety evaluation method and the Luohe group sandstone formation characteristics, using the fuzzy comprehensive evaluation theory, considering the strength of frozen wall, the thickness of the frozen wall, the temperature of the frozen wall, shaft excavation section, groundwater seepage, freezing the formation pressure, the deflection of freezing pipes and the outage time and other major risk factors, the establishment of security method of comprehensive evaluation of construction in Luohe group sandstone stratum, and put forward the construction of disaster control measures to freeze the Luohe group sandstone shaft, construction has positive significance of safety assessment and hazard control in Luohe formation sandstone shaft freezing.