Abstract
The paper deal with the defining stress state of a hoisting shaft lining, lying in the sandy loam, when performing and disturbing the ground freezing technology. The relevance of the performed research lies in the fact that at nonuniform freezing or defrosting, nonuniform stress state is formed, which causes a significant over-stresses of the lining. To research the nonuniform stress state, a spatial finite element model of a hoisting shaft was developed, in which the case of nonuniform ground freezing was simulated. The calculation by the finite-element technique was carried out on the basis of the computational professional complex Structure CAD for Windows. In the course of the analysis, the values of stress state for linings made of reinforced-concrete blocks, B30 concrete, gray and modified cast-iron tubbings. A comparison of the components of stress state for sandy loam at a temperature of -2 °C (freezing), nonuniform freezing and at a temperature of + 8 °C (defrosting) was carried out. It was found that for the proposed geotechnical conditions in the form of soft, water-saturated sandy loam, it is recommended to use a lining made of gray and modified cast-iron tubbings.
Highlights
In the construction of underground facilities in a closed way, for example, deep-laid lines, the opening of the widest front of operations plays an important role at the first stage of construction
The speed in the starting the spread of work and, the time of construction of the objects in a closed way are related to the speed of the hoisting shaft construction, as well as with its further normal operation, which allows performing the continuous plan operation at the bottom level [1]
Compared to the isofields of horizontal stresses in the linings at uniform freezing [6, 8], the maxima of the nonuniform freezing isofields are strongly displaced towards the defrosted grounds and are strongly elongated, at this the shorter part of the isofield is always located at the side of the ground with a greater elasticity modulus, that is, the frozen part
Summary
In the construction of underground facilities in a closed way, for example, deep-laid lines, the opening of the widest front of operations plays an important role at the first stage of construction Such a strategic move requires the creation of an above-ground mine complex, a hoisting shaft and a complex of workings around the shaft. This, in turn, requires the use of special methods of operations that let normal work at the development of grounds and installation of the lining The main of these operation methods, which cuts off underground water from the working area and strengthens the soft grounds of the surrounding massif, is freezing [2,3,4]
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