Determination of technological parameters of rock freezing systems based on the condition of maintaining design thickness of ice wall

Artificial freezing ensures the formation of a temporary ice wall around the shaft under construction, which prevents groundwater penetration into the shaft and increases the strength of rocks around the unsupported walls of the shaft until the permanent support is erected. The purpose of the study is to carry out thermotechnical calculation of ice wall with subsequent theoretical analysis of changing ice wall thickness with shifting to the passive freezing stage. The idea of the study is to determine these technological parameters based on the condition of maintaining the design ice wall thickness at the stage of passive freezing. The methodology and results of thermotechnical calculation of ice wall for the clay layer as applied to the case of the shafts under construction of a potash mine in the Republic of Belarus are presented. The thermal calculation of the ice wall was carried out numerically in the ANSYS software package using the finite element method. The findings of the numerical multiparameter modeling allowed theoretical analysis of ice wall thickness decrease with shifting to the passive freezing stage with higher brine temperature. The decrease in ice wall thickness was studied both during normal operation of the freezing station and at emergency operation mode caused by the failure of one of the freezing columns. Special attention in the analysis was paid to studying the influence of the duration of the active freezing stage and the distance between the columns on the decrease in the ice wall thickness. When analyzing changes in ice wall thickness at different distances between the freezing columns, it was found that the most common column spacing in the range from 1.1 to 1.3 m requires observing restrictions on the duration of active freezing to prevent a critical decrease in ice wall thickness during the passive freezing stage or decreasing the distance between the freezing columns. In this case, preservation of positive dynamics of ice wall thickness growth is ensured. For the clay layer considered in the study and the distance between the columns from 1.1 to 1.3 m, the minimum time of active freezing is also about 4.3 months. As a result of the analysis, the technological parameters of the freezing system (duration of the active freezing stage and the distance between the freezing columns) were determined, at which the ice wall thickness at the passive freezing stage did not become lower than the minimum permissible values calculated based on the strength and creep conditions.

Thermal calculation of the hydraulic drive of the dragline walking mechanism

A new device for moving walking machines is proposed. It allows you to reduce energy consumption for the movement of the dragline by eliminating the friction of the support base on the ground while maintaining the step size and providing a given direction of its movement. The thermotechnical calculation for the hydraulic dragline walking mechanism is presented with the aim of using the heat generated during the dragline movement to heat the driver’s cab during overburden operations at low ambient temperatures. Ill. 1, Ref. 10. Tab. 1.

Исследование изменения теплового режима канализационных сетей в зимний период

Канализационные трубопроводы являются одним из основных элементов системы водоотведения, определяющих ее надежность и экономичность. Система водоотведения г. Кызыла располагается в районах с суровым климатом, отличающимся глубоким сезонным промерзанием грунтов, превышающим 3,2 м. Уменьшение глубины заложения канализационных трубопроводов в этих условиях является актуальной задачей. Цель исследований заключалась в обосновании уменьшения глубины заложения трубопроводов при сохранении надежности работы в нормальном эксплуатационном режиме и обеспечении незамерзаемости в возможных аварийных ситуациях. Представлены результаты натурных экспериментальных исследований по изучению теплового режима на действующей системе канализации г. Кызыла в зимний период. Приведены результаты замеров температуры сточных вод на разных участках канализационной сети в разное время суток. На основе полученных данных выполнен теплотехнический расчет сети, который позволил дать заключение о назначении глубины заложения труб на выпусках из зданий 1,8 м с возможным ее уменьшением в дальнейшем.Sewer pipelines are one of the main components of a sanitation system that determines its integrity and effectiveness. The sanitation system of Kyzyl has been constructed in the areas with a rigorous climate that is characterized by deep seasonal soil freezing exceeding 3.2 m. Reducing the depth of laying sewer pipelines against this background is a critical task. The study was aiming at the substantiation of reducing the pipe laying depth while maintaining the integrity of their operation in the normal way and ensuring non-freezing in possible emergency situations. The results of full-scale studies of the thermal conditions of operating the sanitation system of Kyzyl in winter are presented. The results of wastewater temperature measurements in different sewer network sections at different times of the day are given. Based on the obtained data a thermotechnical calculation of the network was carried out that provided for assigning 1.8 m pipe laying depth of the building drains with possible reduction in future.

Damping Procedure for Mixed Control with Variable Coefficients of the Neighborhood Model

In the article, a bilinear neighborhood model of an installation for maintaining the optimum temperature of the polyol is considered. To determine the heat transfer coefficient, traditional mixed control and mixed control with variable coefficients were carried out. To improve the mixed control procedure with variable coefficients, damping is applied - imposing restrictions on the possible variation of the values of the variable coefficients. A comparison of the results of mixed controls with the results of determining the heat transfer coefficient with the help of thermotechnical calculation is made. The values of the deviations of the neighborhood model are presented for different variants of mixed control.

THERMOTECHNICAL CALCULATION OF FLOORS ABOVE UNHEATED BASEMENT IN COTTAGE EXPLOITED UNDER INTERMITTENT HEATING CONDITIONS

The procedure of thermotechnical calculation of fl oor above unheated basement exploited under intermitt ent heating conditions is presented. Procedure in question is based on research of nonstationary problem of heat transfer through walling and takes into account thermo-inertial characteristics of walling materials. Through the example of fl oor above cottage basement is evaluated energy consumption and walling heating time in passing from stand-by mode to work mode with proposed procedure. Based on calculation results recommendations for energy and heating time saving are presented.

Thermotechnical Calculation of Air Cavities by Rehabilitation of Wet Brickworks

For excessive wet masonry rehabilitation, except for other methods, the method of air cavities is used. These can be wall or floor cavities. The wall cavities may be situated either on the internal or the external side of the wall. From the height point of view, internal side cavities can be located under the floor or above the floor level. This contribution only deals with the cavities above the floor level. In the projection practice, the air cavities usually are designed only empirically. But it is necessary to carry out their thermal technical evaluation for their correct capacity. The matter of the evaluation is the topic of the following contribution.

Characteristic and Application of Facade System ‘Polialpan’

The article is about ventilated system “Polialpan”. Article’s materials are based on estimated data, information taken from Media, different Internet resources, photo and video materials. The aim of the research is to show the possibility of improving of the housing stock, its reconstruction and modernization with using special façade system. It means that in this article we flush out the all details of this facade system. There is thermotechnical calculation, demonstrative that façade system “Polialpan” is satisfy the requirements of normative document. The cost analys is in it too, which is based on the specific residence building in Saint-Petersburg.