RU2141442C1 - Method of erection of underground reservoir in soil - Google Patents

Abstract

FIELD: erection of underground reservoirs; underground storages for liquids and industrial wastes. SUBSTANCE: wells are drilled at inclination relative to central portion of reservoir. Wellhead is formed over upper contour of reservoir. Then soil is washed off and washed-off zone is filled with hardening solution, after which inclined retaining wall is erected and soil is withdrawn from reservoir. EFFECT: reduced consumption of binding solution due to reduced thickness of underground reservoir wall at enhanced stability. 3 dwg

Description

 The invention relates to the construction of underground tanks and can be used for the construction of underground storage of liquid substances and industrial waste in permeable soils.

 A known method of constructing an underground low-temperature ice-rock reservoir in the form of a vertically-cylindrical hole, including drilling vertical wells, creating a retaining wall through them by pumping coolant through the wells to form a solid ice-rock mass along the reservoir contour and subsequent excavation from the reservoir contour (1).

 The disadvantage of this method is the need to create and maintain during operation the retaining ice-rock wall of large thickness to ensure its stability during storage of liquid substances.

 Closest to the proposed technical solution is a method of constructing walling in the soil using jet technology, in which vertical wells are drilled through which a retaining wall is created in the form of intersecting circular piles by circular erosion of the soil with the rise of the hydraulic monitor along the well and simultaneously filling the erosion zone with a binder solution followed by excavation inside the contour bounded by the retaining wall (2).

 The disadvantage of this method is the high consumption of a binder solution, spent on the creation of round piles of large diameter, capable of ensuring the stability of the vertical retaining wall at ground pressure and its tightness.

 The objective of the invention is to reduce the flow rate of the binder solution by reducing the wall thickness of the underground reservoir while increasing its stability.

 As a result of solving this problem, the technology of constructing the retaining wall by the jet technology is simplified, since the soil is washed out in one or two opposite directions without rotating the monitor. Creating inclined walls instead of vertical ones allows to reduce their thickness and guarantees their stability. In addition, the creation of inclined walls of the storage allows you to use the cheapest and easiest bulldozer method of soil development for excavating soil from the tank circuit.

 The essence of the proposed method consists in drilling wells along the contour of the reservoir, creating a retaining wall through them by erosion of the soil and filling the erosion zone with a hardening solution, and excavation inside the contour of the reservoir, while according to the proposed method, the wells are drilled with an inclination to the central part of the reservoir, and the erosion is performed in inclined planes of laying retaining walls.

 Due to the inclination of the retaining wall, the lateral pressure of the soil located outside it decreases, which ensures greater stability of the underground reservoir. When the wall is tilted at an angle of natural repose of the soil, the lateral pressure on the wall is 0.

 The proposed method is illustrated by the diagrams in FIG. 1, 2 and 3.

 In FIG. 1 shows a plan for drilling deviated wells in plan during the construction of an underground reservoir.

 In FIG. 2 shows a sectional diagram of the construction of a retaining wall of an underground reservoir.

 In FIG. 3 shows an underground reservoir in section after excavation from it.

 In FIG. 1-3 shows a well 1 drilled in soil 2 to the level of the bottom 3 of the tank through which the retaining wall 4 is constructed.

 The method of constructing an underground reservoir in the ground by inkjet technology is as follows.

 Drill wells 1 with an inclination towards the central part of the reservoir. The mouths of the wells 1 are located on the upper contour of the tank, and their inclination to the central part of the tank is taken equal to the angle of inclination of the retaining wall 4, which is calculated by the strength characteristics of the soil and material of the retaining wall 4 after hardening of the hardening solution (Fig. 1). Wells 1 are drilled by rotary drilling machines or a special jet installation by means of its hydro-immersion in the ground. The length of the well 1 is determined by the depth of the bottom of the tank 3 and the angle of inclination of the retaining wall 4. Into the well 1 lower the jet monitor, consisting of pipes for supplying a hardening mortar, compressed air and water and horizontal nozzles. The horizontal nozzle of the hydraulic monitor is oriented in the plane of laying of the retaining wall 4 and the retaining wall 4 is constructed by erosion of the soil while lifting the hydraulic monitor up the well 1 while filling the erosion zone with a hardening solution (Fig. 2). If the erosion is carried out with a water jet, then the hardening solution is supplied below the horizontal nozzle, and if the erosion is carried out with a liquid hardening solution, then pressurized water is not used when constructing the retaining wall 4. In the second case, the technology is simplified, but the flow rate of the hardening solution is increased. Air is supplied to the hydraulic monitor to increase the erosion range of a water jet or a stream of a hardening solution. After hardening of the hardening mortar, excavation of the soil 2 inside the tank circuit is carried out. The development of soil 2 is carried out by a bulldozer or excavator with its movement outside the upper contour of the tank. If the bottom 3 of the tank does not reach the water-resistant rocks, then concreting the bottom 3 is made to the junction with the inclined walls 4 (Fig. 3).

 Example 1

An underground reservoir for placement of drilling fluid is built in sandy loam. The angle of repose of sandy loam is 45 ^o . When the depth of the tank is 3 meters and taking into account the time-limited use of the tank, a hardening solution of minimum strength consisting of 90% clay and 10% cement is chosen. Then the angle of the retaining wall 4 is taken equal to the angle of repose of the sandy loam - 45 ^o . The thickness of the retaining wall 4 is taken equal to 20 cm, based on its filtration characteristics.

Along the upper perimeter of the tank at an angle of 45 ^o to its central part by an hydraulic monitor of the jet installation, an inclined well 1 of 4.5 m length to a depth of 3.2 m from the earth's surface passes by the hydro-immersion method. After that, the hydraulic monitor is oriented in the well 1 so that the horizontal nozzle is directed in the plane of the retaining wall 4. In this example, adjacent pairs of wells are located in this plane 1. The soil is washed out with a cement-cement mortar with a density of 1.2 t / m ³ when lifting the hydraulic monitor along well 1 up at a speed of 0.2 m / min. At a pressure on the nozzle of 10 MPa, the range of erosion of the sandy loam will be 2.5 m. After the hydraulic monitor is lifted to the exit of the jet to the surface, the side erosion is stopped, the hydraulic monitor is re-immersed to the depth indicated above and the side nozzle is oriented to the opposite neighboring well 1. Next erosion is repeated according to the above scheme. To ensure the guaranteed closure of the erosion zones when creating the retaining wall 4, the distance between the wells 1 is assumed to be 4.5 m.After the retaining wall is constructed along the entire tank circuit and the clay-cement mixture is strengthened (2 weeks), the excavation is carried out by a bulldozer inside the circuit. The bottom 3 of the tank is covered with a layer of clay-cement mixture of the same composition with a thickness of 20 cm

 Example 2

An underground reservoir for storing concentrated brine is created in loams with an angle of repose of 50 ^o . The depth of the reservoir is 4.5 m. For erosion and the creation of a retaining wall 4, a cement-sand mortar is used, which provides strength after hardening of 5 MPa. The thickness of the retaining wall 4 is taken equal to 20 cm. Given the depth of the reservoir, the strength characteristics of the loam and the material of the retaining wall 4, its angle of inclination is taken equal to 75 ^o . The reservoir construction technology is similar to that described in Example 1. At a solution pressure of 10 MPa at the outlet of the horizontal nozzle, the erosion range is 1.5 m; therefore, the distance between the wells 1 is taken to be 2.5 m. After the cement-sand mortar has hardened for 2 weeks, a notch is made soil inside the tank circuit with an excavator, followed by planning and cementing the bottom 3. The inner surface of the retaining wall 4 is reinforced by covering with a 5 cm layer of cement mortar. After conducting standard hydraulic tests, the underground tank is ready for operation.

Sources of information:
1. SNiP 2.11.04-85. Underground storage of oil, petroleum products and liquefied gases. / Gosstroy of the USSR. - M.: TsITP Gosstroy USSR, 1988.p. 16-17.

 2. Recommendations on inkjet technology for the construction of anti-filter curtains, foundations, foundation preparation and development of frozen soils. All-Russian Research Institute of Foundations and Underground Structures named after N.M. Gersevanov. - M.: 1989, p. 43-50.

Claims (1)

 A method of constructing an underground reservoir in the soil using jet technology, including drilling wells along the reservoir circuit, creating a retaining wall through them by eroding the soil and filling the erosion zone with a hardening solution, followed by excavation of the soil inside the reservoir circuit, characterized in that the wells are drilled with an inclination to the central part of the reservoir and erosion is performed in the inclined planes of the retaining wall.

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