Study On Growing Characteirstics Of Freezing Wall In Cretaceous Layer Of Dahaize Mine Auxiliary Shaft

In this paper, the growing characteristics of freezing wall in Cretaceous soft layer ofDahaize mine is being researched by the means of practical measuring, numericalsimulation and laboratory testing for rock samples brought from project site.On the basis ofactual drilling skew, with the aid of finite element software this paper calculated thedistribution diagram of temperature field and temperature characteristic curve in interfaceat different times. The change of profile temperature field is not simply move of curve, butbow action of parabola upward from the cold source. The freezing wall thickness of eachlayer is increasing but the rate is getting slower. The developing speed of freezing is alsogetting slower with time.According to temperature data collected through the temperaturemeasuring system, considering actual drilling skew, this paper analyze the developingspeed outward of each layer. From slow to fast, the speed sequence is: fine sandstone,medium sandstone, coarse sandstone. The developing speed inward of each layer is also becalculated and analyzed with the measuring results of wellhole wall temperature in relevantlayers. The developing speed inward of freezing wall is larger than the speed outward. Inthe weak position of freezing wall, the writer calculated the effective thickness and averagetemperature when the relevant layers uncover by using formula method. The calculation ofaverage temperature is greatly affected by pitch of freezing holes, saline water’stemperature and so on. Through actually measuring the distribution of temperature in shaftundersurface, the contents summarize that during the temperature range of-2.8℃to1.1℃,it has a temperature change span of about2℃to3℃per1m. The resulting value ofnumerical simulation is close to the data of practical measuring, and the change rule ofboth sides is in agreement. It can be seen that simulating the developing characteristics offreezing temperature field by using software program ANSYS is feasible. Then the writeruse this finite element software forecast the temperature contribution of-622m coal layerwhen the layer uncovers. This paper also gets the wellhole wall temperature, freezing wallthickness, average temperature and developing speed of the coal layer, as well as givesfreezing and sinking suggestions in the end.The writer studied in detail the developing rule of freezing wall in Cretaceous softrock layers with the contrastive analysis of practical measuring and numerical simulation.The actual skew of freezing hole, latent heat of phase change and other factors are fullyconsidered. On the whole, this paper gets a number of reasonable conclusions, andprovides valuable data accumulation and experience for similar project in the future.