Combined grouting method for shield tunnel with strong development of karst under TBM (tunnel boring machine) mode

Abstract

The invention discloses a karst strong development shield tunnel combined grouting method in a TBM (tunnel boring machine) mode, which comprises the following steps: S1, synchronous grouting during propelling: adopting two grouting pipes at the upper part to perform pipe piece wall back grouting during shield propelling, and enabling the synchronous grouting rate to be matched with the tunneling speed of a shield tunneling machine; s2, secondary grouting and ring sealing are conducted at the shield tail position after filling is completed, specifically, a slurry stop hoop is constructed by adopting a double-liquid-slurry injection mode after the duct piece is separated from the shield tail by 6-7 rings, and grouting holes in the top and the two sides are selected for hole opening; and S3, after wall back grouting is completed, hole opening verification is conducted on the upper portion of the rear segment. The operation of directly filling gaps through full grouting and sealing the shield tail through secondary grouting is adopted, a complex pre-treatment structure is not needed, the construction continuity is improved, meanwhile, the phenomena of ground subsidence, upward floating and slab staggering of the duct piece and water leakage can be avoided after the duct piece wall can be rapidly grouted and filled in time, grouting and filling are directly conducted through the duct piece hoisting hole, and the construction efficiency is improved. And the speed is 5 times of that of common secondary grouting.

Description

Technical Field

[0001] The invention relates to the technical field of tunnel construction, and in particular to a combined grouting method for a shield tunnel with strong karst development in a TBM mode. Background Art

[0002] Underground transportation, corresponding to traditional ground transportation, has become a new channel to alleviate urban traffic pressure. There is no doubt that subway transportation is a green project. Due to the complex geological conditions and surrounding buildings in different cities, various geological conditions have to be encountered during the shield construction process. For hard rock formations, construction methods such as dark excavation, earth pressure shield, and TBM shield have to be adopted.

[0003] Since subway construction is mainly located in the main urban area of ​​the city, with dense surrounding buildings, heavy traffic flow, and complex pipelines, traditional construction methods such as blasting and dark excavation cannot be used for the full-section hard rock shield section. Generally, TBM shield machines or TBM / EPB dual-mode shield machines and other excavation methods are used. Because the soil bin is in an open mode and the soil pressure is 0, the synchronous grouting slurry will flow forward into the soil bin due to the grouting pressure, causing mortar adhesion, and in severe cases, it will consolidate the cutterhead, making the cutterhead unable to rotate.

[0004] In view of the stratum loss caused by shield tunneling construction in TBM mode (earth pressure is 0), the disturbance or shear damage around the tunnel, and the infiltration of groundwater will lead to the redistribution of stress in the surrounding rock. In order to prevent the deformation of the tunnel surrounding rock, make the segment lining and the excavated surrounding rock form an integral structure to bear the force together, and reduce the deformation of the segment under its own weight and internal load, it is necessary to fill the back of the segment with pea gravel in time, and inject mortar to consolidate the pea gravel to achieve dense filling of the pores behind the segment. After the pea gravel is filled in the annular space between the segment and the surrounding rock, it should be backfilled and grouted in time to establish a support system for the segment to prevent groundwater loss. The method of spraying pea gravel + synchronous grouting + secondary grouting is adopted.

[0005] This method has many construction procedures, low construction efficiency, high investment cost, poor construction environment in the tunnel, high construction noise, and poor grouting quality of the formed tunnel, which leads to problems such as misalignment and leakage in the later formed tunnel.

[0006] In addition, the prior art also discloses a method for grouting the wall behind the segment in full-section hard rock shield tunnel construction (patent publication number CN110566233B), which adopts a method of directly sealing the shield tail after grouting 40-60% and then filling other gaps with secondary grouting. Although it can control the quality problems such as ground settlement, segment floating, tunnel seepage, and structural damage caused by insufficiency of grouting behind the segment wall in hard rock formation construction, it is necessary to build a corresponding platform to perform the corresponding secondary grouting filling operation during actual use. The preliminary processing structure steps are complicated and cannot be used quickly and adaptably. At the same time, for zero earth pressure excavation, it cannot prevent the secondary grouting liquid behind from flowing to the front of the cutter head, and the secondary grouting is performed separately during grouting and filling. It cannot be quickly filled under the conditions of secondary grouting in time, which easily causes the floating, misalignment and leakage of the segment.

[0007] To this end, the present application proposes a combined grouting method for a shield tunnel with strong karst development under TBM mode to solve the above technical problems. Summary of the invention

[0008] The main purpose of the present invention is to provide a combined grouting method for shield tunnels with strong karst development under TBM mode, which adopts the operation of full grouting to directly fill the gap + secondary grouting to seal the shield tail. The synchronous grouting pipe can be connected to directly fill the gap through the pipe segment lifting hole. The speed is 5 times that of ordinary secondary grouting, and the cost of manual grouting is also reduced to solve the above technical problems.

[0009] The present invention adopts the following technical solutions to solve the above technical problems:

[0010] A combined grouting method for a shield tunnel with strong karst development in a TBM mode comprises the following specific steps:

[0011] S1. Synchronous grouting during advancement: When the shield machine is advancing, two upper grouting pipes are used to perform grouting behind the bottom wall of the segment. The synchronous grouting rate should match the tunneling speed of the shield machine to prevent the synchronous slurry from rushing in front of the cutterhead;

[0012] S2. After filling, secondary grouting is performed at the shield tail to seal the ring: 6 to 7 rings after the segment is removed from the shield tail, double liquid slurry is injected to form a grouting ring hoop. For the secondary grouting of the grouting ring hoop, the top and two sides of the grouting holes are selected for opening, except for the grouting holes of the capping block;

[0013] S3. Verification of grouting effect: After the grouting behind the wall is completed, a hole is opened on the upper part of the rear segment to ensure that the slurry behind the segment wall is densely filled. During the verification process, if the surface of the hole-opening drill bit is covered with slurry, it means that the filling is dense. Otherwise, grouting should be continued until it is densely filled.

[0014] Preferably, the grouting range during the synchronous grouting process in step S1 is 180° of the bottom, and the synchronous grouting volume is 2.5-2.8m3 / ring.

[0015] Preferably, in the step S2, the double-liquid grouting adopts dual control of grouting volume and grouting pressure, the double-liquid grout ratio is water glass: cement slurry = 1:1; the cement slurry ratio is cement: water = 1:1, the initial setting time is controlled at 20s, the grouting pressure is set at 0.2-0.3MPa, and the grouting volume is set at 1.4-1.6m 3 .

[0016] Preferably, in the step S2, a slurry stop ring is applied every 20 rings.

[0017] Preferably, if a curve appears and the pipe segment floats in the step S2, the slurry stop ring is adjusted to be applied every 10 rings thereafter.

[0018] Preferably, in step S2, the stop grouting rings are connected to the quick grouting joints through the synchronous grouting pump of the shield machine to achieve the effect of quickly filling the gap behind the pipe segment wall, and the synchronous mortar is injected into the holes on the upper part of the pipe segment at the trolley position, and the grouting volume is controlled at 53-55m 3 .

[0019] Preferably, the quick grouting joint is composed of a secondary grouting head, a DN50 ball valve, a DN50 thread and a synchronous grouting quick joint connected in one go, wherein:

[0020] The synchronous grouting quick connector is connected to the synchronous grouting equipment through the synchronous grouting pipe. The DN50 thread is welded to one end of the synchronous grouting quick connector. The grouting head is installed on the lifting hole of the assembled pipe segment. The lifting hole of the pipe segment is drilled through with an electric drill and the ball valve is closed.

[0021] Preferably, if the stratum moisture content is greater than 10L / min during the shield tunneling construction in step S3, the interval between the slurry stop rings is adjusted from 20 rings to 10 rings, and during synchronous grouting filling, holes are opened at the upper part of the water stop rings farther away from the shield tail to drain water, and synchronous mortar is supplemented by injection closer to the shield tail. The outflow of slurry from the drain hole indicates that the rear wall of the segment is densely filled.

[0022] The invention provides a combined grouting method for a shield tunnel with strong karst development in a TBM mode.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The present invention solves the shortcomings of numerous construction procedures, low construction efficiency, high investment cost, poor construction environment in the tunnel, high construction noise and poor grouting quality of the formed tunnel by using double-liquid grouting in TBM / EPB shield tunneling to replace the traditional method of spraying pea gravel + synchronous grouting + secondary grouting, as well as the construction work space environment.

[0025] 2. The present invention adopts double-liquid grouting and step-by-step ring sealing during TBM mode excavation. The construction method is simple and easy to implement on site. It not only meets the demand of filling the gaps behind the pipe segments caused by shield machine excavation, but also improves the construction efficiency. It also improves the tunnel dust pollution caused by spraying bean gravel in the tunnel and reduces noise pollution, thereby ensuring construction safety, greatly improving construction efficiency, reducing cost investment, and shortening construction period.

[0026] 3. The grouting method of the present invention utilizing a quick grouting joint can prevent the secondary grouting liquid from flowing to the front of the cutter disc. In addition, the quick grouting joint adopted by the present invention can also be connected to a synchronous grouting pipe for direct filling through the pipe segment hoisting hole. The speed is 5 times that of ordinary secondary grouting, and the cost of manual grouting is also reduced. The degree of mechanization is high, it is more convenient, more efficient, and has a better filling effect.

[0027] 4. The present invention adopts full grouting to directly fill the gap + secondary grouting to seal the shield tail, which effectively solves the problems of slurry flow, incomplete grouting and low construction efficiency in the traditional grouting process. By accurately controlling the range and rate of synchronous grouting, as well as the ratio of double liquid slurry and grouting pressure, it ensures the full filling and rapid solidification of the slurry, thereby enhancing the close bonding between the pipe segment and the surrounding rock.

[0028] 5. The present invention adopts full grouting to directly fill the gap + secondary grouting to seal the shield tail, without the need for complex pre-processing structure, shortening the construction preparation time, improving the continuity of construction, and at the same time being able to promptly and quickly grout the segment wall to avoid ground subsidence, floating dislocation of the segment and water leakage. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The drawings constituting a part of the present application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0030] Figure 1 It is a schematic diagram of the operation flow of the present invention;

[0031] Figure 2 It is a schematic diagram of synchronous grouting behind the segment wall of the present invention;

[0032] Figure 3 It is a schematic diagram of the back grouting of the pipe segment wall of the present invention;

[0033] Figure 4 It is a schematic diagram of the split plane of the quick grouting joint structure of the present invention;

[0034] Figure 5 It is a schematic plan view of the overall structure of the quick grouting joint of the present invention. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0036] In the embodiment, see Figures 1 to 5 .

[0037] like Figure 1 As shown, the present invention provides a combined grouting method for a shield tunnel with strong karst development in a TBM mode, comprising the following specific steps:

[0038] S1. Synchronous grouting during advancement: Figure 2 As shown in the figure, when the shield is advancing, two grouting pipes are used on the upper part to carry out grouting behind the bottom wall of the segment. The synchronous grouting rate should match the excavation speed of the shield machine to avoid the synchronous slurry from rushing in front of the cutterhead. The grouting range is 180° from the bottom. The main purpose is to support the segment after the shield tail is removed, prevent the segment from sinking, and reduce the amount of mortar added in the later stage. Combined with the grouting range, the synchronous grouting amount is tentatively set at 2.5-2.8m 3 / ring;

[0039] S2. After filling, secondary grouting is performed at the shield tail to seal the ring: Figure 3 As shown in the figure, the segment is out of the shield tail 6-7 rings and the double liquid slurry method is used to apply the grouting ring hoop. The grouting holes on the top and both sides of the grouting ring hoop are selected for secondary grouting.

[0040] Except for the capping block grouting hole, the double-liquid grouting adopts dual control of grouting volume and grouting pressure. After field test verification (different strata need to be confirmed by test), the double-liquid grout ratio is water glass: cement slurry = 1:1; the cement slurry ratio is cement: water = 1:1, the initial setting time is controlled at 20s, the grouting pressure is set at 0.2~0.3MPa, and the grouting volume is set at 1.4~1.6m 3 , then apply the stop ring every 20 rings (if a curve appears and the segment floats, adjust to apply the stop ring every 10 rings);

[0041] In addition, in order to meet the need of quickly filling the gap behind the segment, the stop rings are connected to the quick grouting joints through the synchronous grouting pump of the shield machine to achieve the effect of quickly filling the gap behind the segment wall, and the synchronous mortar is injected into the upper part of the segment at the trolley position, and the grouting volume is controlled at 53-55m 3 ;

[0042] At this point, it can be supplemented that for quick grouting joints, Figure 4and Figure 5 As shown, the quick grouting joint is composed of a secondary grouting head, a DN50 ball valve, a DN50 thread and a synchronous grouting quick joint, wherein: the synchronous grouting quick joint is connected to the synchronous grouting equipment through a synchronous grouting pipe, the DN50 thread is welded to one end of the synchronous grouting quick joint, the grouting head is installed on the lifting hole of the assembled pipe segment, and the lifting hole of the pipe segment is drilled through with an electric drill and then the ball valve is closed;

[0043] Furthermore, the quick grouting joint method is characterized by the following construction process:

[0044] L1. The main accessories used in the rapid grouting method are secondary grouting head, DN50 ball valve, DN50 thread, shield synchronous grouting quick connector, etc.;

[0045] L2. First, firmly weld the DN50 thread and one end of the shield synchronous grouting quick connector, install a DN50 ball valve on the other end of the thread, and install the shield secondary grouting head on the other end of the ball valve;

[0046] L3. When grouting is required, install the grouting head on the lifting hole of the assembled pipe segment, then install the DN50 ball valve on the grouting head, use an electric drill to drill through the lifting hole of the pipe segment and then close the ball valve;

[0047] L4. Connect the welding thread of the synchronous grouting quick joint to the installed DN50 ball valve, and finally remove the synchronous grouting pipe from the joint and connect it to the installed quick grouting joint. Finally, use the synchronous grouting equipment to quickly fill the gap behind the pipe segment. The grouting slurry uses the original synchronous grouting slurry, and the mix ratio can be adjusted as needed;

[0048] In summary, this rapid grouting method can meet the needs of fast, efficient, and large-scale backfill grouting in shield tunnels, control ground settlement, reduce the transportation of cement and secondary grouting equipment, reduce construction procedures, greatly improve construction efficiency, reduce cost investment, and better control the problem of floating of tunnel segments in the later stage;

[0049] Combined with the present solution, the grouting method of the quick grouting joint can prevent the secondary grouting liquid behind from flowing to the front of the cutter head. In addition, the quick grouting joint adopted by the present invention can also be connected to the synchronous grouting pipe to directly fill through the pipe segment hoisting hole, and the speed reaches 5 times that of ordinary secondary grouting, which also reduces the cost of manual grouting, has a high degree of mechanization, is more convenient, more efficient, and has a better filling effect.

[0050] It can be further explained that, based on the above steps S1 and S2, full grouting is used to directly fill the gap + secondary grouting is used to seal the shield tail, which effectively solves the problems of slurry flow, incomplete grouting and low construction efficiency in the traditional grouting process. By accurately controlling the range and rate of synchronous grouting, as well as the ratio of double liquid slurry and grouting pressure, the slurry is fully filled and quickly solidified, thereby enhancing the close bonding between the segment and the surrounding rock.

[0051] Compared with the prior art (a method for grouting the wall behind the full-section hard rock stratum shield tunnel construction with patent publication number CN110566233B, which adopts the operation of directly sealing the shield tail after filling 40-60% of the first grouting, and then filling other gaps with the second grouting simultaneously), this scheme adopts the method of sealing the shield tail only with the second grouting after the first filling is completed, without the need for a complex pre-processing structure, shortening the construction preparation time, improving the continuity of construction, and at the same time being able to timely and quickly grout the wall behind the segment to avoid ground settlement, floating displacement of the segment and water leakage;

[0052] S3. Verification of grouting effect: After the grouting behind the wall is completed, a hole is opened on the upper part of the rear segment to ensure that the grout behind the segment wall is densely filled. During the verification process, if the surface of the hole drill bit is covered with grout, it means that the filling is dense. Otherwise, grouting should be continued until the filling is dense;

[0053] In addition, if the ground water content is greater than 10L / min during the shield excavation construction, the interval between the slurry stop rings is adjusted from 20 rings to 10 rings. During the synchronous grouting filling, holes are opened at the upper part of the water stop rings farther away from the shield tail to drain water, and synchronous mortar is supplemented by injection at the part closer to the shield tail. The slurry flowing out of the drain hole indicates that the back of the segment wall is densely filled.

[0054] In summary, the present invention makes full use of TBM / EPB shield tunneling synchronous grouting to replace the traditional method of spraying bean gravel + synchronous grouting + secondary grouting, which solves the shortcomings of numerous construction procedures, low construction efficiency, high investment cost, poor construction environment in the tunnel, high construction noise and poor grouting quality of the formed tunnel. At the same time, the shield machine of the present invention adopts double-liquid grouting step-by-step ring sealing during TBM mode excavation. The construction method is simple and easy to implement on site. It not only meets the demand for filling the gaps behind the pipe segments caused by shield machine excavation, but also improves the construction efficiency, and also improves the tunnel dust pollution and noise pollution caused by spraying bean gravel in the tunnel, ensuring construction safety, greatly improving construction efficiency, reducing cost investment, and shortening construction period.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0056] In addition, it should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components in a certain specific posture. If the specific posture changes, the directional indication will also change accordingly.

[0057] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the meaning of "and / or" appearing in the full text includes three parallel schemes. Taking "A and / or B" as an example, it includes scheme A, or scheme B, or schemes that A and B meet at the same time. In addition, in the embodiments of the present invention, "multiple" refers to more than two. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in the field to implement. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A combined grouting method for a shield tunnel with strong karst development in a TBM mode, characterized in that: The specific steps include: S1. Synchronous grouting during advancement: When the shield machine is advancing, two upper grouting pipes are used to perform grouting behind the bottom wall of the segment. The synchronous grouting rate should match the tunneling speed of the shield machine to prevent the synchronous slurry from rushing in front of the cutterhead; S2. After filling, secondary grouting is performed at the shield tail to seal the ring: 6 to 7 rings after the segment is removed from the shield tail, double liquid slurry is injected to form a grouting ring hoop. For the secondary grouting of the grouting ring hoop, the top and two sides of the grouting holes are selected for opening, except for the grouting holes of the capping block; S3. Verification of grouting effect: After the grouting behind the wall is completed, a hole is opened on the upper part of the rear segment to ensure that the slurry behind the segment wall is densely filled. During the verification process, if the surface of the hole-opening drill bit is covered with slurry, it means that the filling is dense. Otherwise, grouting should be continued until it is densely filled.

2. The combined grouting method for shield tunnels with strong karst development under TBM mode according to claim 1, characterized in that: The grouting range of the synchronous grouting process in step S1 is 180° of the bottom, and the synchronous grouting volume is 2.5-2.8m 3 / ring.

3. The combined grouting method for shield tunnels with strong karst development under TBM mode according to claim 1, characterized in that: In the step S2, the double-liquid grouting adopts dual control of grouting volume and grouting pressure, the double-liquid grout ratio is water glass: cement slurry = 1:1; the cement slurry ratio is cement: water = 1:1, the initial setting time is controlled at 20s, the grouting pressure is set at 0.2-0.3MPa, and the grouting volume is set at 1.4-1.6m 3 .

4. The combined grouting method for shield tunnels with strong karst development under TBM mode as claimed in claim 3, characterized in that: In the step S2, a stop ring is applied every 20 rings.

5. The combined grouting method for shield tunnels with strong karst development under TBM mode as claimed in claim 4, characterized in that: If a curve or floating of the pipe segment occurs in the step S2, the slurry stop ring is applied every 10 rings.

6. The combined grouting method for shield tunnels with strong karst development under TBM mode according to claim 1, characterized in that: In step S2, the grouting rings are connected to the quick grouting joints through the synchronous grouting pump of the shield machine to quickly fill the gap behind the pipe segment wall, and the synchronous mortar is added to the holes on the upper part of the pipe segment at the trolley position. The grouting volume is controlled at 53-55m 3 .

7. The combined grouting method for shield tunnels with strong karst development under TBM mode according to claim 6, characterized in that: The quick grouting joint is composed of a secondary grouting head, a DN50 ball valve, a DN50 thread and a synchronous grouting quick joint, wherein: The synchronous grouting quick connector is connected to the synchronous grouting equipment through the synchronous grouting pipe. The DN50 thread is welded to one end of the synchronous grouting quick connector. The grouting head is installed on the lifting hole of the assembled pipe segment. The lifting hole of the pipe segment is drilled through with an electric drill and the ball valve is closed.

8. The combined grouting method for shield tunnels with strong karst development under TBM mode according to claim 1, characterized in that: If the ground water content is greater than 10L / min during the shield tunneling construction in step S3, the interval between the grouting rings is adjusted from 20 rings to 10 rings. During the synchronous grouting filling, holes are opened at the upper part of the water stop rings farther away from the shield tail to drain water, and synchronous mortar is supplemented by injection at the part closer to the shield tail. The slurry flowing out of the drainage hole indicates that the rear wall of the segment is densely filled.

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