RU2223403C1 - Process of preparation of mass of permafrost and flooded rock mass for driving workings - Google Patents

Abstract

FIELD: mining industry, construction of mining works and engineering structures in permafrost regions. SUBSTANCE: process of preparation of mass of permafrost and flooded rock mass for driving workings includes decrease of level of highly mineralized water in mass, its conveying and discharge into water intake. After fall of level of mineralized water in rock mass concentration of salts in this water in zone of sinking of each working is reduced by means of injection of heated fresh water into mass up to value at which freezing point of water in each zone is higher than temperature of rock mass. EFFECT: raised safety, shortened time and diminished expenses for preparation of rock mass while driving workings under complex conditions. 4 dwg

Description

The invention relates to the mining industry and can be used for sinking vertical, inclined and horizontal workings during the construction of underground mining enterprises in permafrost areas.

There is a method of preparing an array of permafrost and flooded rocks for driving workings, for example, vertical shafts using freeze wells that are drilled from the surface to the bottom of the aquifer in a concentric circle in the immediate vicinity of the stem location [1].

The disadvantages of this method are the high cost of time and money for freezing rocks around the mine, as well as significant inefficient costs for lowering the temperature of frozen rocks above the aquifer.

A known method of protecting mine workings from underground saline water, including pumping into a water-bearing layer in the places where the workings of finely dispersed fresh pulp is laid and freezing, with the preliminary laying of waterproof explosives and blasting them [2].

The disadvantage of this method is that the injected fresh pulp penetrates into the nearest cracks around the wells, displacing highly mineralized water, and after freezing creates a non-monolithic protective zone around the output. In addition, with large inflows of highly mineralized water to the places where the workings are laid, this water is washed out of the pulp from the system of cracks around the wells, as a result, a protective zone is not formed.

There is a method of preparing an array of permafrost and flooded rocks for tunneling, including lowering the level of highly mineralized water in the array due to its pumping, removal from the array and discharge into the water intake [3]. This method is accepted by us as a prototype.

The disadvantage of this method is that in the place of laying of the mine workings after pumping underground highly saline waters, a significant part of them remains in the array at a static pressure of up to 40 ... 80 m water column, which creates the possibility of water breakthrough and flooding of the mine workings during their penetration.

The objective of the proposed method is to ensure safety when conducting workings in an array of permafrost and watered rocks in difficult conditions, when there are significant inflows of highly mineralized water with high static pressure in the roof of an aquifer, as well as reducing the time and cost of preparing the massif.

This is achieved by the fact that in the method of preparing an array of permafrost and flooded rocks for sinking, including lowering the level of highly mineralized water in the array, draining and discharging it into the water intake, after lowering the level of mineralized water in the rock mass, reduce the salt concentration in this zone laying each output by, for example, injecting heated fresh water into the array to a value at which the freezing temperature of water in each zone is higher than the temperature of the rock mass.

The injected fresh water in the zone of laying the workings replaces and dilutes highly mineralized water in them, reducing the concentration of salts in this water to the limit at which desalinated water freezes and forms, together with frozen rocks, a monolithic zone that ensures safe passage of the workings.

In Fig.1, 2 shows vertical sections of horizontal development along the axis and perpendicular to it in an array of flooded permafrost rocks.

Figure 3, 4 shows the vertical and horizontal sections of the trunk in an array of permafrost rocks with an aquifer.

A method of preparing an array of permafrost and flooded rocks for sinking excavations is as follows.

In the rock mass in zone 1 of development 2 (drift, trunk, slope, etc.), the level of underground highly mineralized water 3 of the underground aquifer 4 is lowered to a predetermined value by means of a well system 5. When determining the static pressure of this water above the bottom of the aquifer 4 or soil horizontal excavation 2 take into account the geological conditions of the array and the requirements for the safety of mining operations. As a rule, this value is in the range of 5 ... 10 m water column. The pumped-out water is diverted through a pipeline and discharged into a water intake (not shown). After lowering the level of mineralized water to a predetermined value, the concentration of salts in it is reduced by, for example, pumping heated fresh water through additional wells 6. The pressure and temperature of highly saline waters are monitored using sensors installed in the control wells 7, and the concentration of salts in these waters is determined by regularly taking water samples from the wells and analyzing them in the laboratory. As test and measurement wells, water-reducing and water-injection wells can be used. According to the readings of the temperature sensor in the well, the temperature of the rock mass is determined, and the freezing temperature of this water is determined by the concentration of salts in the sample water. The process of injecting fresh water is stopped when the freezing temperature of the water in the sample is higher than the temperature of the rock mass in zone 1 of the workings. As a result, in the aquifer 4 in the area contoured by the boreholes 5, the desalinated mineralized water freezes and, together with the frozen rocks, forms a solid monolithic shell that ensures safety during excavation. Thus, this method provides the preparation of an array of rocks of the aquifer 4 in the zone of development 2 without the cost of artificial freezing.

An example implementation of the method

An array of permafrost and irrigated rocks with a salt content of 110 g / l and water temperature of rocks consisting of fractured dolomites, -1.6 ° C, is prepared for drifting with a cross section of 9.1 m ² . The static pressure of mineralized water over the soil of the planned drift is 60 m water column. To reduce the pressure of mineralized water, six vertical water-reducing wells are drilled at the same distance from each other along the axis of this drift. Highly saline water is pumped through the indicated wells with drainage and discharge into the catchment. Since the massif is represented by dolomites, the residual static pressure of mineralized water above the drift soil is 10 m water cent. Simultaneously with the reduction to the specified level, 16 additional wells are drilled 25 meters long parallel to the axis of the projected drift at a distance of not more than 30 cm deep from its contour. Upon reaching the static pressure of mineralized water level of 10 m water above the drift soil, heated fresh water begins to be pumped through additional wells. The temperature of the rock mass and the pressure of mineralized water are controlled using commercially available sensors installed in a control water-reducing well, the concentration of salts in water is determined in samples taken monthly from the control well in the drift circuit. After five days, the salt concentration in the water reached 20 g / l, at which the freezing temperature of mineralized water is -1.2 ° C, and the process of pumping heated fresh water is stopped. Then, within three days, the desalinated mineralized water completely frozen in the drift zone, which ensured its safe passage. Array preparation for driving the drift was carried out in a shorter time by 3-4 times, the cost of it was 2-3 times lower compared to the method of preparing the array with artificial freezing.

An example of preparing an array of permafrost rocks with an aquifer for sinking a vertical wellbore differs in that vertical water-reducing wells are drilled from the surface uniformly around the circumference around the axis of the projected trunk to the bottom of the aquifer. Becoming pipes in each of them is perforated to the height of the aquifer. Mineral water is pumped out until its static pressure level of 10 m water column is reached. above the sole of this horizon. Injection wells are also drilled in a concentric circle around the axis of the bore. Heated fresh water is injected to dilute mineralized water for similar mining and geological conditions of the deposit for 5-15 days, natural desalination of desalinated water in the massif of frozen rocks is 5-10 days. This also ensures the safety of the barrel. The cost of preparing an array of permafrost watered rocks for drilling the proposed method is 5-8 times, depending on the depth of the aquifer of mineralized water, lower compared to the method of artificially freezing highly mineralized water in a rock mass using freezing wells from the surface.

Sources of information

1. Construction of mining in difficult mining conditions. Handbook. / Ed. B.A. Cartesia. - M: Nedra, 1992, p. 198-206.

2. Copyright certificate No. 1726773, cl. E 21 D 1/12, 05/31/89

3. Copyright certificate No. 1665736, cl. E 02 D 19/10, May 22, 89 prototype.

Claims (1)

A method of preparing an array of permafrost and flooded rocks for sinking, including lowering the level of highly mineralized water in the array, draining and discharging it into the water intake, characterized in that after lowering the level of mineralized water in the rock mass, the salt concentration in this water in the zone of each production by, for example, injection of heated fresh water into the array to a value at which the freezing temperature of water in each zone is higher than the temperature of the rock mass.

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