A grouting method for shield construction in water-rich sand and gravel strata

Abstract

A shield construction grouting method for water-rich sand and gravel strata, the steps of which are: S1, prefabrication of special segments, and reservation of grouting holes; S2, installation of anchoring membranes and anchoring rings for assembly; S3, assembly of special segments adjacent to anchoring rings; S4, shield advancement construction; S5, secondary grouting construction of segments. The shield construction grouting method proposed by the present invention improves the synchronous grouting process, can prevent the slurry from being flushed out by water, and ensure the strength of the slurry after solidification; can restrict the grouting range, and solve the uncertainty of slurry diffusion; the grouting body outside the segment forms a whole surrounding the segment, and has good reinforcement and water-stopping effects; compared with the synchronous grouting of double-liquid slurry, it has the advantages of simple process and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnel construction, and in particular to a grouting method for shield construction in water-rich sand and gravel strata. Background Art

[0002] Water-rich gravel strata are common strata in underground engineering construction in my country. They are characterized by loose structure, high permeability and large porosity. They are typical mechanically unstable strata. During shield construction, the size of the shield cutterhead and the shield body is larger than the outer diameter of the segment. After the segment escapes from the shield tail, a gap is formed. At present, the technology mainly uses synchronous grouting and secondary grouting to fill the pores to control surface settlement. Grouting materials can be single-liquid slurry and double-liquid slurry. Among them, single-liquid slurry is easily diluted when it comes into contact with water, has serious loss and is unconstrained. Single-liquid slurry has poor effect in water-rich, high-pressure gravel strata. Double-liquid slurry has the characteristics of short gel time, good injectability and high early strength. Compared with single-liquid cement slurry, double-liquid slurry has stronger resistance to groundwater dilution. However, it is difficult to control the setting time of double-liquid grouting. If the concentration or dosage of water glass is too high, the slurry will set too early, which is not conducive to the diffusion of the slurry to the designed grouting range, and it is easy to cause the reinforcement of the soil between the holes to be loose and the cost is high. If the concentration or dosage is too low, the setting time of the slurry will be too long, and the slurry will be easily flushed by groundwater during grouting, resulting in a large amount of grouting material loss.

[0003] At present, there is a scheme in the prior art to lay grouting bags on the back of shield segments. CN107191197A discloses a shield segment and its construction method in a shield empty push through a mining tunnel. The segment wall has grouting holes inside and outside the grouting bag coverage area, which are used to inject slurry into the grouting bag and inject slurry into the gaps between the grouting bags. This technical solution requires secondary grouting of the segment area not covered by the grouting bag, and still cannot solve the problem of poor grouting effect in water-rich sand and gravel formations. CN114776323A discloses a method for controlling shield tunnel formation and double compensation of stress loss. The grouting bag is laid on the back of the shield segment and is separately grooved and buried on the back of the shield segment. This technical solution reserves grouting holes in the middle of the segment, and cannot achieve a synchronous grouting effect. An independent bag is set on the outside of the segment, and the outside of the segment cannot form an integral grouting body, and the gap between the grouting bags becomes a weak link behind the segment. At the same time, the solution does not provide a solution for installing the bag and the segment, and it is difficult to implement secondary grouting outside the bag. Therefore, the existing technical solutions cannot solve the problem of poor grouting effect of shield construction in water-rich sand and gravel strata, and it is impossible to form an integral grouting body outside the segment in this stratum. Summary of the invention

[0004] The present invention aims to solve the deficiencies of the prior art and provides a grouting method for shield construction in water-rich sand and gravel strata. The method proposes a grouting membrane technology for externally placed segments. Grouting is performed when the segments begin to come out of the shield tail. The grouting range is controlled by the grouting membrane, which solves the uncertainty problems of slurry being flushed out by groundwater and slurry diffusion, expands the application range of single-liquid grouting materials, and has the advantages of simple process and low cost compared to double-liquid slurry.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A grouting method for shield construction in water-rich sand and gravel strata, comprising the following steps:

[0007] S1. Prefabrication of special segments with reserved grouting holes:

[0008] Two grouting holes are reserved on a single segment, namely the synchronous grouting hole and the secondary grouting hole. A grouting stop valve made of PE material is first inserted into the synchronous grouting hole to prevent grout leakage from the hole that has not been grouted.

[0009] S2. Install anchoring membrane and assemble anchoring ring:

[0010] Before the shield starts, the end is reinforced by cement soil mixing method; after the shield starts, the second ring before leaving the reinforcement body is the anchor ring, which is used for grouting membrane anchoring; special segments are used starting from the ring before leaving the reinforcement body; the anchor ring is a conventional segment, and after the segment is transported to the segment yard, the anchor membrane can be installed simultaneously when the water stop strip on the side of the segment is installed; adhesive is applied to the outside of each segment of the anchor ring, and the anchor membrane is pasted, and a margin is reserved for the anchor membrane on the axial outer edge of the segment for sewing with the next ring; the segment installed with the anchor membrane is transported to the assembly machine position of the shield machine by the segment vehicle, and the anchor ring is assembled;

[0011] S3. Assembly of adjacent special segments of anchor rings:

[0012] After the anchor ring assembly is completed, the special segment assembly begins; the shield jack is retracted, and the grouting membrane behind the segment is laid. The grouting membrane reserves margins in the circumferential and axial directions of the special segment to facilitate sewing with adjacent membranes; the grouting membrane is sewn with the circumferentially adjacent membranes and the anchoring membrane using handheld sewing equipment, and then the special segment is assembled. After the grouting membrane is sewn with the circumferentially adjacent membranes, the grouting membrane behind the special segment forms a whole in the circumferential direction;

[0013] S4, shield tunneling construction:

[0014] After the shield jack tightens the pipe segment, the excavation and excavation construction continues. The grouting membrane is anchored by the anchoring membrane at the front end of the tunnel axis and is pressed by the shield tail brush at the rear end. The grouting body slurry is in the closed space formed by the grouting membrane; the shield tail is detached from the synchronous grouting hole of the special pipe segment, and grouting begins through the synchronous grouting hole. The grouting volume and grouting pressure are monitored. After the theoretical grouting volume is reached, the grouting is stopped, the synchronous grouting holes are blocked, and the excavation proceeds to the next ring to start assembling the special pipe segment. The shield jack retracts, and the grouting membrane behind the special pipe segment is laid. After the grouting membrane is sewn with the adjacent membranes in the annular direction and the tunnel axial direction by hand-held sewing equipment, the next ring of special pipe segments is assembled, and S4 is repeated to complete the entire tunnel excavation;

[0015] S5. Secondary grouting construction of pipe segments:

[0016] After the slurry has initially set, a geological radar is used to scan the area behind the segment, and secondary grouting is carried out on the void area outside the grouting body. A handheld hole-opening device is used to open up the secondary grouting hole and the grouting body after initial setting. A stop valve is inserted into the hole and the grouting equipment is connected. A double-liquid slurry with a high water glass concentration is injected into the external void area to achieve rapid plugging of local voids. After the secondary grouting is completed, the secondary grouting hole is blocked.

[0017] The anchoring membrane is made of geotextile material and has the characteristics of being impermeable to water and slurry.

[0018] The grouting membrane material is a canvas material, which has the characteristics of being impermeable to water and grout, and the mechanical properties of the material are determined by experiments;

[0019] Among them, materials that meet the material elongation are selected according to the excavation diameter and the outer diameter of the segment. The material elongation should be able to ensure that the volume of the grouting body after grouting is not less than the pore volume of the shield tail segment.

[0020] The tensile strength of the membrane material of the anchoring membrane is not less than the membrane stress after the grouting body is formed.

[0021] In the step S4, margins are reserved for the grouting membrane in both the circumferential direction and the axial direction of the tunnel to facilitate sewing with adjacent membranes.

[0022] The plane position of the synchronous grouting hole is close to the edge of the pipe segment.

[0023] The synchronous grouting hole is a through hole, with a threaded PE material grouting pipe built in, which can be threadedly connected to the external grouting pipeline during synchronous grouting.

[0024] The beneficial effects of the present invention are as follows: the shield construction grouting method proposed in the present invention improves the process of synchronous grouting, can avoid the slurry being released by water, and ensure the strength of the slurry after solidification; can constrain the grouting range and solve the uncertainty of slurry diffusion; the grouting body outside the segment forms a whole surrounding the segment, with good reinforcement effect and water-stopping effect; compared with the dual-liquid slurry synchronous grouting, it has the advantages of simple process and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the shield construction process in the present invention;

[0026] Figure 2 It is a partial enlarged schematic diagram of the pipe segment after grouting in the present invention;

[0027] Figure 3 It is a side schematic diagram of the tube segment in the present invention;

[0028] Figure 4 It is a plane schematic diagram of the pipe segment in the present invention;

[0029] Figure 5 It is a cross-sectional schematic diagram of the grouting hole in the present invention;

[0030] Figure 6 It is a cross-sectional schematic diagram of the stop slurry valve of the present invention;

[0031] In the figure: 1-shield machine; 2-reinforcement body; 3-special segment; 4-conventional segment; 5-grouting body; 6-grouting membrane; 7-anchoring membrane; 8-shield tail brush; 9-secondary grouting hole; 10-synchronous grouting hole; 11-grouting stop valve;

[0032] The following is a detailed description of the embodiments of the invention with reference to the accompanying drawings. DETAILED DESCRIPTION

[0033] The present invention will be further described below in conjunction with the accompanying drawings and embodiments:

[0034] like Figure 1-Figure 6 As shown, a shield construction grouting method for water-rich sand and gravel strata, the steps are:

[0035] S1. Prefabrication of special segments with reserved grouting holes:

[0036] Two grouting holes are reserved on a single segment, namely a synchronous grouting hole 10 and a secondary grouting hole 9. A grouting stop valve 11 made of PE material is first inserted into the synchronous grouting hole 10 to prevent grouting leakage from the hole that has not been grouted. The plane position of the synchronous grouting hole 10 is close to the edge of the segment, which is convenient for timely grouting when the segment begins to escape from the shield tail, so as to achieve the purpose of synchronous grouting. The synchronous grouting hole 10 is a through hole with a threaded PE material grouting pipe built in, which can be threadedly connected with the external grouting pipeline during synchronous grouting.

[0037] S2. Install anchoring membrane and assemble anchoring ring:

[0038] Before the shield is started, the end is reinforced by cement soil mixing method; after the shield is started, the second ring before leaving the reinforcement body 2 is an anchor ring, which is used for grouting membrane anchoring; the ring before leaving the reinforcement body 2 begins to use a special pipe segment 3; the anchor ring is a conventional pipe segment 4, and after the pipe segment is transported to the pipe segment yard, the anchor membrane 7 can be installed simultaneously when the water stop strip on the side of the pipe segment is installed; adhesive is applied to the outer side of each pipe segment of the anchor ring, and the anchor membrane 7 is pasted, and the anchor membrane 7 is reserved at the axial outer edge of the pipe segment for sewing with the next ring; the anchor membrane 7 is made of geotextile material and has the characteristics of impermeability and grouting, and the pipe segment installed with the anchor membrane 7 is transported to the assembly machine position of the shield machine 1 by a pipe segment vehicle to assemble the anchor ring;

[0039] S3. Assembly of adjacent special segments of anchor rings:

[0040] After the anchor ring assembly is completed, the special segment 3 is assembled; the shield jack is retracted, and the grouting membrane 6 is laid behind the segment. The grouting membrane 6 has a margin in both the circumferential and axial directions of the special segment 3 to facilitate sewing with adjacent membranes; the grouting membrane 6 is sewn with the circumferentially adjacent membranes and the anchoring membrane 7 respectively using a handheld sewing device, and then the special segment 3 is assembled. Among them, after the grouting membrane 6 is sewn with the circumferentially adjacent membranes respectively, the grouting membrane 6 behind the special segment 3 forms a whole in the circumferential direction; the grouting membrane 6 is made of canvas material, which has the characteristics of impermeability to water and grouting, and the mechanical properties of the material are determined by experiments;

[0041] Among them, the material that meets the material elongation is selected according to the excavation diameter and the outer diameter of the segment. The material elongation should be able to ensure that the volume of the grouting body 5 after grouting is not less than the pore volume of the shield tail segment;

[0042] The tensile strength of the membrane material of the anchoring membrane 7 is not less than the membrane stress after the grouting body 5 is formed;

[0043] S4, shield tunneling construction:

[0044] After the shield jack tightens the pipe segment, the excavation and excavation construction continues. The grouting membrane 6 is anchored by the anchoring membrane 7 at the front end of the tunnel axis, and the rear end is pressed by the shield tail brush 8. The grouting body 5 slurry is in the closed space formed by the grouting membrane 6; the shield tail is detached from the synchronous grouting hole 10 of the special pipe segment 3, and grouting is started through the synchronous grouting hole 10. The grouting volume and grouting pressure are monitored. After the theoretical grouting volume is reached, the grouting is stopped, and the synchronous grouting hole 10 is blocked. The excavation is advanced to the next ring and the special pipe segment 3 is assembled. The shield jack is retracted, and the grouting membrane 6 behind the special pipe segment 3 is laid. After the grouting membrane 6 is sewn with the adjacent membranes in the annular direction and the tunnel axial direction respectively with a handheld sewing device, the next ring of special pipe segments 3 is assembled, and S4 is repeated to complete the entire tunnel excavation; the grouting membrane 6 is reserved with margins in the annular direction and the tunnel axial direction to facilitate sewing with adjacent membranes;

[0045] S5. Secondary grouting construction of pipe segments:

[0046] After the slurry has initially set, a geological radar is used to scan the area behind the segment, and secondary grouting is carried out on the hollow area outside the grouting body 5. A handheld hole-opening device is used to open up the secondary grouting hole 9 and the grouting body 5 after initial setting. A stop valve 11 is inserted into the hole and then the grouting equipment is connected. Double-liquid slurry with a high water glass concentration is injected into the external hollow area to achieve rapid plugging of local voids. After the secondary grouting is completed, the secondary grouting hole 9 is blocked.

[0047] The grouting membrane 6 is made of canvas material, which has the characteristics of being impermeable to water and grout, and the mechanical properties of the material are determined by experiments;

[0048] Among them, the material that meets the material elongation is selected according to the excavation diameter and the outer diameter of the segment. The material elongation should be able to ensure that the volume of the grouting body 5 after grouting is not less than the pore volume of the shield tail segment.

[0049] The synchronous grouting hole 10 is located in a plane close to the edge of the pipe segment.

[0050] The synchronous grouting hole 10 is a through hole, which has a threaded PE material grouting pipe built in it, and can be threadedly connected to an external grouting pipeline during synchronous grouting.

[0051] In the description of the invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0052] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0053] In the invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be fixedly connected, detachably connected, or integrated; it can be mechanically connected, electrically connected, or able to communicate with each other; it can be directly connected, or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0054] The invention is described above by way of example in conjunction with the accompanying drawings. It is obvious that the specific implementation of the invention is not limited to the above-mentioned method. As long as various improvements are made using the method concept and technical solution of the invention, or they are directly applied to other occasions without improvement, they are all within the scope of protection of the invention.

Claims

1. A grouting method for shield construction in water-rich sand and gravel strata, characterized in that: The steps are: S1. Prefabrication of special segments with reserved grouting holes: Two grouting holes are reserved on a single pipe segment, the two grouting holes are a synchronous grouting hole (10) and a secondary grouting hole (9), and a grouting stop valve (11) made of PE material is first inserted into the synchronous grouting hole (10) to prevent grouting leakage from the hole that has not been grouted; S2. Install anchoring membrane and assemble anchoring ring: Before the shield machine starts, the end is reinforced by cement soil mixing method; after the shield machine starts, the second ring before leaving the reinforcement body (2) is an anchor ring for grouting membrane anchoring; the special pipe segment (3) is used from the ring before leaving the reinforcement body (2); the anchor ring is a conventional pipe segment (4), and after the pipe segment is transported to the pipe segment yard, the anchor membrane (7) can be installed simultaneously when the water stop strip on the side of the pipe segment is installed; adhesive is applied to the outer side of each pipe segment of the anchor ring, and the anchor membrane (7) is attached, and a margin is reserved for the anchor membrane (7) at the axial outer edge of the pipe segment for sewing with the next ring; the pipe segment installed with the anchor membrane (7) is transported to the assembly machine position of the shield machine (1) by a pipe segment vehicle, and the anchor ring is assembled; S3. Assembly of adjacent special segments of anchor rings: After the anchor ring assembly is completed, the special segment (3) is assembled; the shield jack is retracted, and the grouting membrane (6) is laid behind the segment, and the grouting membrane (6) is reserved with margins in both the circumferential and axial directions of the special segment (3) to facilitate sewing with adjacent membranes; the grouting membrane (6) is sewn with the circumferentially adjacent membranes and the anchoring membrane (7) respectively using a handheld sewing device, and then the special segment (3) is assembled, wherein, after the grouting membrane (6) is sewn with the circumferentially adjacent membranes respectively, the grouting membrane (6) behind the special segment (3) forms a whole in the circumferential direction; S4, shield tunneling construction: After the shield jack is tightened against the pipe segment, the excavation and excavation construction is continued. The grouting membrane (6) is anchored by the anchoring membrane (7) at the front end of the tunnel axis and is pressed by the shield tail brush (8) at the rear end. The grouting body (5) is in the closed space formed by the grouting membrane (6). The shield tail is detached from the synchronous grouting hole (10) of the special pipe segment (3), and grouting is started through the synchronous grouting hole (10). The grouting volume and grouting pressure are monitored. After the theoretical grouting volume is reached, the grouting is stopped, and the synchronous grouting hole (10) is blocked. The excavation is continued to the next ring and the special pipe segment (3) is assembled. The shield jack is retracted, and the grouting membrane (6) behind the special pipe segment (3) is laid. The grouting membrane (6) is sewn with the adjacent membranes in the annular direction and the tunnel axis respectively by a handheld sewing device, and then the next ring of special pipe segments (3) is assembled. S4 is repeated to complete the whole tunnel excavation. S5. Secondary grouting construction of pipe segments: After the slurry has initially set, a geological radar is used to scan the area behind the pipe segment, and secondary grouting is performed on the hollow area outside the grouting body (5). A handheld hole-opening device is used to open the secondary grouting hole (9) and the grouting body (5) after initial setting. A slurry stop valve (11) is inserted into the hole and then connected to the grouting equipment. A double-liquid slurry with a high water glass concentration is injected into the external hollow area to achieve rapid plugging of the local hollow area. After the secondary grouting is completed, the secondary grouting hole (9) is plugged.

2. A grouting method for shield construction in water-rich sand and gravel strata according to claim 1, characterized in that: The anchoring membrane (7) is made of geotextile material.

3. A grouting method for shield construction in water-rich sand and gravel strata according to claim 2, characterized in that: The material of the grouting membrane (6) is canvas material; Among them, the material with the appropriate elongation is selected according to the excavation diameter and the outer diameter of the segment. The elongation of the material should be able to ensure that the volume of the grouting body (5) after grouting is not less than the pore volume of the shield tail segment.

4. A grouting method for shield construction in water-rich sand and gravel strata according to claim 3, characterized in that: The tensile strength of the membrane material of the anchoring membrane (7) is not less than the membrane stress after the grouting body (5) is formed.

5. A grouting method for shield construction in water-rich sand and gravel strata according to claim 4, characterized in that: In the step S4, the grouting membrane (6) is provided with margins in both the circumferential direction and the axial direction of the tunnel, so as to facilitate sewing with adjacent membranes.

6. A grouting method for shield construction in water-rich sand and gravel strata according to claim 5, characterized in that: The synchronous grouting hole (10) is located in a plane close to the edge of the pipe segment.

7. A grouting method for shield construction in water-rich sand and gravel strata according to claim 6, characterized in that: The synchronous grouting hole (10) is a through hole, in which a threaded PE material grouting pipe is internally placed, and is threadedly connected to an external grouting pipeline during synchronous grouting.

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