RU2367740C1 - Method of ground consolidation under buildings and facilities - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention concerns construction and can be applied in soft ground consolidation under buildings and facilities during tunnel driving under them. Method involves defining zone of load effect generated by overhead ground, building or facility, before tunnel driving under buildings and facilities. When tunnel crosses this zone, holes are bored from tunnel along upper tunnel outline at given angle against tunnel axis at equal distance in driving direction. Pitch of further hole boring outlines in the defined zone is calculated by expression: L = lcosα-2, where L is pitch between hole boring outlines, m; l is hole depth in outline, m; α is hole tilt angle towards tunnel axis, degrees. Further each hole outline undergoes sequential processing by feeding acid to holes over sealing device 8 to dissolve carbonate inclusions in ground, with further injection of consolidating solution, such as binder with oxalic acid. When tunnel is driven in soft ground, additionally tilted holes are bored in direction opposite to tunnel driving course.

EFFECT: enhanced ground stability under buildings and facilities.

2 cl, 1 dwg

Description

The invention relates to construction and can be used to consolidate soft soils under buildings and structures when tunneling under them.

There is a method of fixing the soil under buildings and structures, including drilling wells from the surface, followed by pumping cement or soil-cement mortar into them, which is prepared for each geological zone depending on the voltage created by the soil mass and structure [1].

The disadvantage of this method is that to fix the soil in each geological zone, it is necessary to carry out a large amount of drilling, since the wells are drilled from the surface.

There is a method of fixing the soil under the building and structure, including drilling in the soil from the surface of vertical and deviated wells, the axes of which intersect or intersect under the foundation, then a fixing solution is pumped into these wells, followed by a time delay to gain soil strength [2]. This method is taken by us as a prototype.

The disadvantage of this method is that deviated wells have a significant length in the area with increased load created by the mass of soil and the building, and before the injection of the fixing solution, the soil softens and deforms.

The objective of the invention is to increase the stability of the soil under the building and / or structure by creating several protective loops as the tunnel advances in the area affected by the load created by the overlying soil, building and / or structure.

This is achieved by the fact that in the method of securing the soil under buildings and weapons, including drilling in the soil of deviated wells and injecting a fixing solution into them, first, before tunneling under the buildings and structures, the zone of the impact on it of the load created by the overlying soil, building and structure is determined, then, when the tunnel crosses this zone from the tunnel, the wells are drilled along its upper contour at a given angle to the axis of the tunnel and at the same distance between them in the direction of penetration, while following the contours collaring wells in said zone is determined from the expression

L = lcosα-2,

where L is the step between the contouring of the wells, m;

l - well depth in the circuit, m;

α is the angle of inclination of the well to the axis of the tunnel, deg,

then, each well contour is sequentially processed by supplying an acid in them, which ensures the dissolution of carbonate inclusions in the soil, followed by injection of a fixing solution, which uses a fastener with oxalic acid.

In addition, when tunneling in weak soils, inclined wells are additionally drilled in the opposite direction of tunneling.

The drawing shows a schematic diagram of the consolidation of soil under buildings and structures.

The method of fixing soil under buildings and structures is as follows.

Before driving the tunnel under the building and structure, the zone 1 of the impact of the load created by the overlying soil 2, building 3 and / or structure (not shown) is preliminarily determined on the tunnel 4 by a known method. The place of drilling in the circuit of the tunnel is taken at the site of its entry into the zone of impact of the load on the tunnel. Then from the tunnel along the upper contour 5, wells 6 are drilled at the same distance from each other. Depending on the physical and mechanical properties of the soil and a given margin of safety of the roof, the angle of inclination of the wells to the axis of the tunnel is selected in accordance with experimental data in the range of α = 10-20 °. The depth of the wells depends on the set value of the tunnel per day, and the number of wells in the circuit is determined based on the size of the diameter of the tunnel. To ensure a stable position of the building and / or structure along the entire length of the zone of the impact of the load on the tunnel, several drilling circuits 7 are drilled, the step between which is determined from the expression

L = lcosα-2,

where L is the step between the contours of the drilling wells;

l - well depth in the circuit, m;

α is the angle of inclination of the well to the axis of the tunnel, deg.

Next, sequentially process each circuit. First, acid, for example, hydrochloric acid, which dissolves carbonate inclusions in the soil, and then injects the fixing solution, is simultaneously fed into the wells of one circuit through a sealing device 8. For this, a polymer, for example, KM-8 with a volume of 60-70%, is poured into the mixing unit 9, and then 40-30% of oxalic acid is added. All components are thoroughly mixed in this installation for 5-10 minutes. The obtained fixing solution is pumped using the injection pump 10 into the soil through the wells. The solution penetrates to a depth of 12-14 m and in a radius of 1.5-2.0 m from the well. As a result, a solid polymer-soil skeleton is formed in the soil along the semi-perimeter of the tunnel, which prevents displacement of the earth's surface during the construction of the tunnel and creates long-term stability of the soil. When tunneling in soft soils, inclined wells 11 are additionally drilled in the opposite direction of tunnel tunneling.

An example implementation of the described method.

The tunnel under construction has a diameter of 14.2 m and runs at a depth of h = 10 m under a building of historical value. The soil is characterized by the following physical and mechanical properties: porosity 0.3-0.4, natural humidity W = 0.2-0.6, soil density ρ = 1.5-1.7 t / m ³ , angle of internal friction φ = 24-25 degrees., The filtration coefficient K _f = 3-6 10 ^-4 m / day. Previously, before tunneling under the building, the zone of the impact on it of the load created by the overlying soil and the building is determined by a known method. For these conditions, this zone is located at a distance of 24.8 m from the contour of the foundation of the building. The place of drilling wells in the circuit of the tunnel is taken at the site of its entry into the zone of impact of the load on the tunnel. To ensure uniform distribution of the load on the tunnel, the wells are drilled along its upper contour at the same distance from each other and at an angle to the axis of the tunnel equal to 15 ° with a margin of safety of the roof of the tunnel of 20 kN. The depth of the well in the circuit is in the range of 14-18 m with a tunnel of 12-16 m per day. For specific conditions, the number of wells drilled along the contour of the tunnel is 20-22 with a distance between them of 0.8-1.0 m. The length of the impact zone on the tunnel of the load of overlying soil and the building is 150 m. The step of the subsequent contouring of wells in this zone is determined from the above expression, which is equal to 12 m. Thus, 10 loops with 20 wells in each loop will be drilled. Well treatment is carried out simultaneously in each circuit by supplying acid, for example hydrochloric acid, to the dissolution of carbonate inclusions in the soil through a G-1B-type sealing device, followed by injection of a fixing solution, which includes KM-8 fastener, and oxalic acid. As a result of fixing the soil around the tunnel under construction, deformational displacements of the soil and the displacement of the building above the tunnel under construction are excluded, which ensures increased soil stability under the buildings and / or structures.

Information sources

1. RF patent No. 2133795 according to class. E02D 3/12, 1998.

2. RF patent No. 2103441, cl. 6 E02D 3/12, 1986 (prototype).

Claims (2)

1. The method of securing the soil under buildings and structures, including drilling in the soil of deviated wells and injecting a fixing solution in them, characterized in that before the tunnel is excavated under the buildings and structures, the zone of exposure to the load created by the overlying soil, building and structure is determined, then, when the tunnel crosses this zone, they drill from the tunnel of the well along its upper contour at a given angle to the axis of the tunnel and at the same distance between them in the direction of penetration, and the step after blowing contouring wells in the specified zone is determined from the expression
L = Lcosα-2,
where L is the step between the contouring of the wells, m;
L is the depth of the well in the circuit, m;
α is the angle of inclination of the well to the axis of the tunnel, deg,
then, each well contour is sequentially processed by supplying an acid in them, which ensures the dissolution of carbonate inclusions in the soil, followed by injection of a fixing solution, which uses a fastener with oxalic acid. 2. The method according to claim 1, characterized in that when tunneling in soft soils, additionally drilled deviated wells in the opposite direction of tunneling.

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