Method for lifting subway shield tunnel by polymer grouting

Description

CROSS REFERENCE OF RELATED APPLICATION

The present invention claims priority under 35 U.S.C. 119(a-d) to CN 202410687977.9, filed May. 30, 2024.

BACKGROUND OF THE PRESENT INVENTION

Field of Invention

The present invention relates to a technical field of shield tunnel lifting by grouting, and more particularly to a method for lifting a subway shield tunnel by polymer grouting.

Description of Related Arts

Subway shield tunnels are often affected by external environments such as construction of adjacent pits, changes in water table, and sudden pile loads on ground surface, which tends to deform due to insufficient structural strength, or suffer settlement far beyond expectation due to long-term railroad traffic loading on the highly compressible and structurally soft soils lying underneath the shield tunnels. Uneven settlement may lead to tube sheet breakage and leakage, which deteriorates the structural stress state, affects the traveling limit and track smoothness, and poses a serious threat to structural and operational safety.

Conventionally, grouting is a commonly used shield tunnel settlement treatment, which can reinforce the soil to improve compactness and bearing capacity, reduce tunnel settlement, and repair the tunnel settlement through slurry lifting. Conventional tunnel settlement repair methods mainly adopt drilling and grouting in the tunnel, which will cause certain damage to the structure, and the high water pressure during hole drilling is a highly potential danger. Besides, it is difficult for construction equipment to enter and exit the tunnel, and the operation period is long, both affecting the operation of trains. The grouting material is usually slurry with normal density, and no expansive polymer material is reported to have been used in the repair of tunnel settlement. From the aspect of application effect, although conventional method can prevent settlement from further development, it is difficult to lift the structure and to restore the original design elevation of tube sheets. Chinese patent application CN202311254545.0 disclosed a reusable device and a construction method for foundation settlement disposal of immersed tube tunnels in operation, which need to close the tunnel lanes before grouting and lifting up, and the traffic can only be resumed after the cement slurry has solidified, which has a long operation cycle, requires a maintenance step and is prone to cause traffic congestion.

SUMMARY OF THE PRESENT INVENTION

In order to solve the technical problems in the prior art, an object of the present invention is to provide a method for lifting a subway shield tunnel by polymer grouting.

Accordingly, in order to accomplish the above object, the present invention provides a method for lifting a subway shield tunnel by polymer grouting, comprising steps of:

• • S1, detecting settlement of the shield tunnel, and determining a settlement location, a settlement range and a settlement amount;
  • S2, drilling a row of isolation barrier holes on both sides of a settlement repair area, and injecting quick-setting slurry into the isolation barrier holes, in such a manner that two isolation barriers are formed after the quick-setting slurry is cured, which are used to restrain a soil body within the settlement repair area;
  • S3, drilling grouting channel holes from ground with an inclined hole guided drilling rig, and then drilling horizontal grouting holes below the settlement;
  • S4, connecting grouting pipes to geotextile bags, and feeding the geotextile bags into each of the grouting holes in turn;
  • S5, using a polymer grouting system to inject polymer slurry into the geotextile bags through the grouting pipes in an order from two sides to middle, wherein the polymer slurry then expands to lift up a soil layer above and jack up a tunnel structure; and
  • S6, after lifting, filling and sealing the grouting channel holes.

The method of the present invention is capable of efficiently and quickly lifting, wherein the whole processes, including drilling, grouting and lifting are simple and fast; the polymer slurry expands and cures rapidly without the need of maintenance, so as to realize the rapid lifting of the tunnel settlement. The construction is convenient and barely affected by spatial and temporal factors. Grouting is performed on the ground with developed polymer grouting equipment, which is hardly affected by construction site restrictions and does not affect the normal operation of the subway lines. The method is economic and eco-friendly, convenient and fast, which requires no excavation, and saves manpower, material and financial resources. No excess waste will be produced, which will not affect the surrounding facilities and environments. Polymer materials are green and pollution-free. The lifting effect is stable and controllable. The slurry is injected from two sides to the middle, so as to ensure rapid lifting. The slurry expands and solidifies inside the geotextile bags to form stable and homogeneous slurry column, wherein the slurry expands and spreads within pre-designed range. The slurry also expands and lifts up the soil layer between the two isolation barriers, thereby restraining the soil in the settlement repair area and avoiding randomness and uncontrollability of slurry spreading.

Preferably, the step S1 further comprises: determining locations, quantity, lengths, diameters, spacings, depths from a tunnel bottom, and single-hole grouting volumes of the grouting holes according to the settlement of the shield tunnel. To ensure that an overall force of the shield tunnel is more uniform after grouting, the length of the grouting hole should not be too short, so as to avoid deformation, cracking, and other damages to the tunnel tube sheets.

Preferably, the step S1 further comprises: determining locations of the isolation barrier holes. A row of isolation barrier holes is drilled on each side of the settlement repair area with a horizontal drilling technology, thereby restraining the soil body within the settlement repair area.

Preferably, in the step S3, a lifting distance is left between the grouting holes and a tunnel bottom, so as to prevent a huge expansion force generated after grouting from impacting the tunnel tube sheet in close proximity to cause deformation, cracking and other damages thereto.

Preferably, in the step S4, openings of the grouting pipes are placed into open ends of the geotextile bags, and the open ends are hooped onto the grouting pipes with hoops. With high strength, high temperature resistant and impermeability, the geotextile bags will not be damaged when the slurry reacts with exothermic heat and expands within the bag, and the slurry will not seep out of the bag, so that after expanding and solidifying, the slurry forms a stable slurry column with the geotextile bag, increasing the overall compressive strength.

Preferably, the isolation barrier holes and the grouting holes are both horizontally oriented and are perpendicular to an axial direction of the shield tunnel, so as to lift the soil layer above as a whole in the horizontal direction, thereby lifting the tunnel tubes and jacking up the tunnel structure as a whole.

Preferably, lengths of the geotextile bags are greater than lengths of the grouting holes, and diameters of the geotextile bags after being expanded are greater than diameters of the grouting holes, ensuring that the slurry column formed by grouting is only constrained by the soil body rather than the geotextile bag until it expands to a maximum diameter.

Preferably, the polymer slurry is a two-component self-expanding polyurethane polymer.

Compared with the prior art, beneficial effects of the present invention are as follows: the method of the present invention is capable of efficiently and quickly lifting, wherein the whole processes, including drilling, grouting and lifting are simple and fast; the polymer slurry expands and cures rapidly without the need of maintenance, so as to realize the rapid lifting of the tunnel settlement. The construction is convenient and barely affected by spatial and temporal factors. Grouting is performed on the ground with developed polymer grouting equipment, which is hardly affected by construction site restrictions and does not affect the normal operation of the subway lines. The method is economic and eco-friendly, convenient and fast, which requires no excavation, and saves manpower, material and financial resources. No excess waste will be produced, which will not affect the surrounding facilities and environments. Polymer materials are green and pollution-free. The lifting effect is stable and controllable, where the slurry expands and solidifies in the geotextile bag, forming a stable and homogeneous slurry column. The slurry is injected from two sides to the middle, so as to ensure rapid lifting while avoiding tunnel tube sheet deformation. The slurry expands and spreads within pre-designed range. The slurry also expands and lifts up the soil layer between the two isolation barriers, thereby restraining the soil in the settlement repair area and avoiding randomness and uncontrollability of slurry spreading. The lifting effect is durable. The polymer grouting material is also durable and corrosion resistant, and it can squeeze and reinforce the surrounding soil to avoid secondary settlement. There is a lifting distance between the grouting holes and the tunnel bottom, so that multiple homogeneous and stable slurry columns are formed by a certain distance from the tunnel bottom after grouting, which makes the tunnel uniformly stressed and prevents the tunnel tube sheets from deformation, cracking and other damages.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to further illustrate the technical solutions in embodiments of the present invention or prior art, the accompanying drawings will be briefly introduced below. It will be obvious that the accompanying drawings described below are only some of the embodiments of the present invention, and that other drawings can be obtained according to the structures illustrated in the drawings by those of ordinary skill in the art, without creative labor.

FIG. 1 is a flow chart of a method for lifting a subway shield tunnel by polymer grouting according to the present invention;

FIG. 2 is a cross-sectional view of a grouting hole according to the method of the present invention;

FIG. 3 is a cross-sectional view of geotextile bag arrangement according to the method of the present invention;

FIG. 4 is a cross-sectional view from one side of the shield tunnel according to the method of the present invention; and

FIG. 5 is a cross-sectional view from one side of the shield tunnel during lifting according to the method of the present invention.

ELEMENT REFERENCE

• • 1—shield tunnel; 2—inclined hole guided drilling rig; 3—isolation barrier hole; 4—isolation barrier; 5—grouting channel hole; 6—grouting hole; 7—geotextile bag; 8—grouting pipe; 9—hoop; 10—polymer grouting system; 11—slurry column.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. It should be noted that the described embodiments are only a part of all the embodiments of the present invention. Based on the following embodiments, all other embodiments obtained by those of ordinary skill in the art without creative labor shall fall within the protection scope of the present invention.

It should be noted that all directional indications such as first, second, up, down, left, right, front, back . . . in the embodiments of the present invention are only used to explain the relative position, movement, etc., between the components in a particular attitude as shown in the accompanying drawings, and that the directional indications may be changed correspondingly if the particular attitude is changed.

In addition, the technical solutions between the various embodiments of the present invention may be combined with each other, but it must be based on the fact that the person skilled in the art can realize it. When the combination of technical solutions appears to be contradictory or unattainable, it should be considered that the combination of such technical solutions does not exist, and is not within the protection scope claimed by the present invention.

Referring to FIGS. 1-5 of the drawings, the present invention provides a method for lifting a subway shield tunnel by polymer grouting, comprising steps of:

• • S1, detecting settlement of the shield tunnel 1, and determining a settlement location, a settlement range and a settlement amount;
  • S2, drilling a row of isolation barrier holes 3 on both sides of a settlement repair area, and injecting quick-setting slurry into the isolation barrier holes 3, in such a manner that two isolation barriers 4 are formed after the quick-setting slurry is cured, which are used to restrain a soil body within the settlement repair area;
  • S3, drilling grouting channel holes 5 from ground with an inclined hole guided drilling rig 2, and then drilling horizontal grouting holes 6 below the settlement;
  • S4, connecting grouting pipes 8 to geotextile bags 7, and feeding the geotextile bags 7 into each of the grouting holes 6 in turn;
  • S5, using a polymer grouting system 10 to inject polymer slurry into the geotextile bags 7 through the grouting pipes 8 in an order from two sides to middle, wherein the polymer slurry then expands to lift up a soil layer above and jack up a tunnel structure; and
  • S6, after lifting, filling and sealing the grouting channel holes 5.

The method of the present invention is capable of efficiently and quickly lifting, wherein the whole processes, including drilling, grouting and lifting are simple and fast; the polymer slurry expands and cures rapidly without the need of maintenance, so as to realize the rapid lifting of the tunnel settlement. The construction is convenient and barely affected by spatial and temporal factors. Grouting is performed on the ground with developed polymer grouting equipment, which is hardly affected by construction site restrictions and does not affect the normal operation of the subway lines. The method is economic and eco-friendly, convenient and fast, which requires no excavation, and saves manpower, material and financial resources. No excess waste will be produced, which will not affect the surrounding facilities and environments. Polymer materials are green and pollution-free. The lifting effect is stable and controllable. The slurry is injected from two sides to the middle, so as to ensure rapid lifting. The slurry expands and solidifies inside the geotextile bags 7 to form stable and homogeneous slurry columns 11, wherein the slurry expands and spreads within pre-designed range. The slurry also expands and lifts up the soil layer between the two isolation barriers 4, thereby restraining the soil in the settlement repair area and avoiding randomness and uncontrollability of slurry spreading. The lifting effect is durable. The polymer grouting material is also durable and corrosion resistant, and it can squeeze and reinforce the surrounding soil to avoid secondary settlement. There is a lifting distance between the grouting holes 6 and the tunnel bottom, so that multiple homogeneous and stable slurry columns 11 are formed by a certain distance from the tunnel bottom after grouting, which makes the tunnel uniformly stressed and prevents the tunnel tube sheets from deformation, cracking and other damages.

Preferably, the step S1 further comprises: determining locations, quantity, lengths, diameters, spacings, depths from a tunnel bottom, and single-hole grouting volumes of the grouting holes 6 according to the settlement of the shield tunnel 1. To ensure that an overall force of the shield tunnel 1 is more uniform after grouting, the length of the grouting hole 6 should not be too short, so as to avoid deformation, cracking, and other damages to the tunnel tube sheets.

Referring to FIGS. 1, 4 and 5, the step S1 further comprises: determining locations of the isolation barrier holes 3. A row of isolation barrier holes 3 is drilled on each side of the settlement repair area with a horizontal drilling technology, thereby restraining the soil body within the settlement repair area.

Referring to FIG. 5, in the step S3, a lifting distance is left between the grouting holes 6 and a tunnel bottom, so as to prevent a huge expansion force generated after grouting from impacting the tunnel tube sheet in close proximity to cause deformation, cracking and other damages thereto.

Referring to FIG. 5, in the step S4, openings of the grouting pipes 8 are placed into open ends of the geotextile bags 7, and the open ends are hooped onto the grouting pipes 8 with hoops 9. With high strength, high temperature resistant and impermeability, the geotextile bags 7 will not be damaged when the slurry reacts with exothermic heat and expands within the bag, and the slurry will not seep out of the bag, so that after expanding and solidifying, the slurry forms a stable slurry column 11 with the geotextile bag 7, increasing the overall compressive strength.

Referring to FIGS. 4 and 5, the isolation barrier holes 3 and the grouting holes 6 are both horizontally oriented and are perpendicular to an axial direction of the shield tunnel 1, so as to lift the soil layer above as a whole in the horizontal direction, thereby lifting the tunnel tubes and jacking up the tunnel structure as a whole.

In addition, lengths of the geotextile bags 7 are greater than lengths of the grouting holes 6, and diameters of the geotextile bags 7 after being expanded are greater than diameters of the grouting holes 6, ensuring that the slurry column formed by grouting is only constrained by the soil body rather than the geotextile bag 7 until it expands to a maximum diameter.

Preferably, the polymer slurry is a two-component self-expanding polyurethane polymer.

It is to be understood that the above embodiments are described only to illustrate the technical route and features of the present invention, which are intended to enable persons skilled in the art to understand the content of the present invention and implement it accordingly, but not intended to be limiting. Any changes or modifications made within the claimed scope of the present invention shall be covered within the protection scope of the present invention.