Starting construction method of earth pressure balance shield machine

Abstract

The invention discloses a starting construction method of an earth pressure balance shield machine, and relates to the technical field of shield construction. Comprising the following steps that a construction hole is reinforced, and after reinforcement, core drilling sampling is adopted for checking the uniformity and self-supporting performance of a soil body after reinforcement; a steel sleeve is customized according to the size of a construction hole, annular brushes are arranged in the steel sleeve and provided with annular brush bristles with the tail ends extending towards the side of the hole, the steel sleeve is provided with a grease filling hole, the grease filling hole is located between the two annular brushes, and the inner side length of the annular brush bristles is larger than the outer side length of the annular brush bristles. The annular bristles are gradually close to the steel sleeve from the outer side bottom end to the inner side bottom end; the steel sleeve is installed to a construction hole, and then a grouting pipe is installed; sealing treatment is conducted on the construction hole, and pressure maintaining testing is conducted after sealing treatment; and the shield tunneling machine starts tunneling construction. The launching construction method of the earth pressure balance shield machine has the beneficial effects of being easy to install, good in sealing performance and high in pressure bearing capacity.

Description

Technical Field

[0001] The present invention relates to the technical field of shield construction, and particularly to a method for starting the construction of an earth pressure balance shield machine. Background Art

[0002] With the rapid development of urban rail transit, the shield tunneling method has become the preferred method for urban underground tunnel construction due to its significant technical advantages such as safety, high quality, high efficiency, and environmental protection. As the first link of shield construction, the starting of the shield into the tunnel directly determines the success or failure of subsequent shield tunneling. Especially in unstable strata such as highly permeable and water-rich sand layers, the risk of starting the shield is extremely high. During the entry of the shield machine into the tunnel, it is very easy to cause the phenomenon of gushing at the portal, which may lead to soil and water loss in the strata, resulting in risks such as ground settlement and collapse at the portal end, and causing the failure of the shield starting.

[0003] For shield starting in such strata, the conventional portal sealing method is a rubber curtain and a hinged flap at the portal. This sealing method has a simple structure, but it cannot ensure the sealing performance of the portal in unstable strata such as highly permeable and water-rich sand layers. Affected by the soil and water pressure of the strata, it is very easy to lead to seal failure, resulting in the risk of water and sand gushing during shield starting.

[0004] Therefore, how to safely and quickly start the shield in the environment of highly permeable and water-rich sand layers under limited reinforcement conditions has become a difficult problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that the conventional sealing method in the prior art cannot play a role in unstable strata such as highly permeable and water-rich sand layers. The purpose is to provide a method for starting the construction of an earth pressure balance shield machine, adopting corresponding technical solutions, and having the beneficial effects of easy installation, good sealing performance, and strong pressure-bearing capacity.

[0006] The present invention is achieved by the following technical solutions: The present invention provides a method for starting the construction of an earth pressure balance shield machine, which includes the following steps: S1. Reinforce the construction portal to ensure the stability of the soil mass when the shield breaks through into the strata. After reinforcement, core sampling is used to test the uniformity and self-standing ability of the soil mass after reinforcement; S2. Customize a steel sleeve according to the size of the construction portal. An annular brush is arranged inside the steel sleeve. The annular brush has annular bristles extending towards the portal side at the end. The steel sleeve is provided with a grease filling hole, and the grease filling hole is located between the two annular brushes. The inner length of the annular bristles is greater than the outer length of the annular bristles, and the bottom end of the outer side of the annular bristles gradually approaches the steel sleeve from the bottom end of the inner side; S3. Install the steel sleeve on the construction portal, and then install the grouting pipe; S4. Seal the construction opening, and conduct a pressure-holding test after the sealing treatment. S5. The shield machine starts tunneling construction.

[0007] Furthermore, in the present invention, one end of the steel sleeve is provided with a first circular plate connected to the embedded steel ring, the other end of the steel sleeve is provided with a second circular plate, a rubber curtain cloth, a third circular plate and a fixing plate are sequentially arranged on the outer side of the second circular plate, and a flap is rotatably connected to the fixing plate.

[0008] Furthermore, in the present invention, a fourth circular plate is sleeved in the middle of the steel sleeve, a first stiffening plate with two ends respectively connected to the first circular plate and the fourth circular plate is connected to the outer wall of the steel sleeve, a second stiffening plate with two ends respectively connected to the fourth circular plate and the second circular plate is also connected to the outer wall of the steel sleeve, the inner end of the fixing plate extends into the hole of the steel sleeve, a third stiffening plate is arranged on the outer wall of the fixing plate, and the third stiffening plate extends to the flap.

[0009] Furthermore, in the present invention, the circular brush further includes a fixed head, two fixed heads are connected to the steel sleeve, one of the fixed heads is connected to the annular brush bristles, the other fixed head is provided with an elastic strip connected to the end of the annular brush bristles, and the elastic strip is provided with a V-shaped elastic part.

[0010] Furthermore, in the present invention, an annular airbag is arranged on the annular brush bristles and the elastic strip installed on the steel sleeve, the cross section of the annular airbag is triangular, the annular airbag is connected with a nozzle, the nozzle is connected with an air pump, and the air pump controls the pressing degree of the annular airbag on the annular brush bristles to adapt to different support requirements of the annular brush bristles during greasing and starting.

[0011] Furthermore, in the present invention, in step S4, grease is applied to the two circular brushes. When applying the grease, separate the annular brush bristles and apply the grease to the bottom of the circular brush, apply it densely without leaving gaps, and ensure that the grease in the circular brush forms a closed loop.

[0012] Furthermore, in the present invention, the reinforcement treatment in S1 includes double-fluid jet grouting piles. Double-fluid jet grouting piles are adopted on one side of the portal of the tunnel. The width is at least 3 m outward from the side line of the tunnel structure on each side, and the depth is not less than 1 m from the ground to the bottom of the tunnel. The reinforcement material used is cement slurry with a water-cement ratio of 1.0 - 1.5.

[0013] Further, in the present invention, the reinforcement treatment in S1 includes WSS ground vertical grouting reinforcement. Grouting holes are arranged in the form of plum blossom piles with a spacing of 1.0 m on one side of the portal. The width extends at least 3 m outward from the tunnel structure side line, and the depth is not less than 1 m from the ground to the tunnel bottom. The reinforcement material used is a cement-sodium silicate double-fluid grout with a slurry ratio of 1:1 by volume.

[0014] Further, in the present invention, the core drilling sampling inspection in S1 satisfies a permeability coefficient less than 1.0×10-5 cm / s. Several horizontal exploration holes are drilled at the construction portal, and the water flow rate of each hole does not exceed 20 L / h.

[0015] Further, in the present invention, 12 grouting holes are arranged on the outer side of the steel sleeve. Four of them are used as main grouting holes for connecting with the grouting pipe, and the remaining 8 are used as grease injection holes for injecting shield tail grease during the process. The grease injection holes are all independently connected to a grease injection pump.

[0016] Compared with the prior art, the present invention has the following advantages and beneficial effects: Good sealing performance: In addition to the original rubber curtain and flap, two additional circular brushes are added as sealing measures. All four seals are closely attached to the shield body of the earth pressure balance shield machine, and on this basis, an annular cavity is formed to fill the shield tail grease, greatly improving the sealing performance of the sealing structure; Strong pressure-bearing capacity: The steel sleeve is made of all steel. During the shield launching stage, a pressure resistance test is carried out through bentonite slurry, which can effectively ensure the safety of the shield launching into the tunnel; Good economic benefits: The steel sleeve, circular brush, etc. used for the portal seal can be prefabricated in the factory in advance, saving the construction period of ground reinforcement and greatly reducing the overall cost of the engineering project, which helps to promote green and low-carbon construction and sustainable development. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings: Figure 1 is a partial cross-sectional view of the steel sleeve of the present invention; Figure 2 is a cross-sectional view of the steel sleeve of the present invention; Figure 3 is a cross-sectional view of a circular brush of the present invention; Figure 4 is a cross-sectional view of another circular brush of the present invention; Figure 5 Schematic diagram of the double - pipe jet - grouting pile reinforcement of the present invention; Figure 6 Schematic diagram of the WSS ground vertical grouting reinforcement of the present invention.

[0018] Reference numerals in the drawings and corresponding component names: 1 - construction opening, 101 - embedded steel ring, 2 - steel sleeve, 201 - first circular plate, 202 - second circular plate, 203 - third circular plate, 204 - fourth circular plate, 205 - first stiffening plate, 206 - second stiffening plate, 207 - grease filling hole, 3 - circular brush, 301 - annular bristles, 302 - fixing head, 303 - elastic strip, 304 - V - shaped elastic part, 4 - rubber curtain, 5 - fixing plate, 501 - flap, 502 - third stiffening plate, 6 - annular airbag, 601 - air nozzle. Specific embodiments

[0019] To make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the embodiments and the drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and do not limit the present invention. The following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0020] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if the terms "set", "installed", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0021] Embodiment, in combination with Figures 1 to 6 As shown, it is a related schematic diagram of the starting construction method of the earth pressure balance shield machine according to the embodiment of the present invention. The starting construction method of the earth pressure balance shield machine is applicable to poor geological conditions such as water - rich sand layers, and the specific method is described as follows.

[0022] To ensure the stability of the soil mass when the earth pressure balance shield machine breaks through the opening and enters the formation, it is necessary to reinforce the construction opening 1. This is to avoid sudden water and sand gushing when the sealing structure of the construction opening 1 has not yet established a stable sealing effect, which may cause an instantaneous impact on the sealing structure, resulting in sealing failure and the risk of settlement and collapse of the starting head formation. The reinforcement method can be reasonably selected according to the on-site construction conditions, and Φ800 double-fluid jet grouting piles or WSS ground vertical grouting reinforcement methods can be used.

[0023] In this embodiment, as shown in Figure 5 the double-fluid jet grouting pile reinforcement method is as follows: on one side of the portal, Φ800@600 double-fluid jet grouting piles are used, with 118 designed hole positions. The length of the reinforced body is 3m, the width extends 3m outward from each side of the tunnel structure side line, and the depth is not less than 1m from the ground to the bottom of the tunnel. In this implementation, the reinforcement depth is 15.8m. The reinforcement material is selected as cement slurry, and the water-cement ratio is 1.0 - 1.5.

[0024] In this embodiment, as shown in Figure 6 the WSS ground vertical grouting reinforcement is as follows: on one side of the portal, the grouting hole positions are arranged in the form of plum blossom piles at a spacing of 1.0m. The length of the reinforced body is 3m, the width extends 3m outward from each side of the tunnel structure side line, and the depth is not less than 1m from the ground to the bottom of the tunnel. The reinforcement material is selected as cement-sodium silicate double-fluid slurry, and the slurry ratio is 1:1 by volume; and the grouting parameters are: the slurry diffusion radius is 1.0m, the grouting pressure is 2 - 3 bar, and the average soil injection rate is 30% - 40% by volume.

[0025] After the reinforcement treatment, it is necessary to test the soil mass. Core samples are taken from the reinforced soil mass for inspection. The permeability coefficient should be less than 1.0×10-5 cm / s. Observe and judge whether the cores of the reinforced soil mass have good uniformity, that is, the cores are complete without obvious defects. And the self-standing property is detected, that is, it can remain upright in the natural state for at least 12 hours or more. It is also necessary to detect that there is no obvious water seepage on the heading face. There are 9 horizontal exploration holes at the portal, the depth of the horizontal exploration holes is 2.5 - 3m, and the water flow rate of each hole does not exceed 20L / h, which means the reinforcement is qualified.

[0026] After the reinforcement is completed, it is necessary to customize the steel sleeve 2 according to the size of the construction opening 1. As shown in Figure 2 the steel sleeve 2 is made of a 1000mm wide and 20mm thick steel plate. There are 12 grouting holes on the surface of the steel sleeve 2. Among them, four grouting holes are used as the main grouting holes 208. The grouting holes 208 are connected to the grouting pipes. The grouting pipes are selected as iron pipes with a length of 300mm and a diameter of 25mm, and there is a ball valve inside the iron pipes. The remaining eight grouting holes are used as grease injection holes 207. The grease injection holes 207 are independently connected to the grease injection pump for injecting tail seal grease.

[0027] In this embodiment, as shown in Figure 1As shown in the figure, a first circular ring plate 201 is installed at the left end of the steel sleeve 2, and a second circular ring plate 202 is installed at the right end of the steel sleeve 2. The left first circular ring plate 201 is used to connect with the embedded steel ring 101 in the construction opening 1, and the connection method can be bolt connection. In order to increase the structural strength of the steel sleeve 2, a fourth circular ring plate 204 is installed in the middle of the steel sleeve 2, and a first stiffening plate 205 and a second stiffening plate 206 are fixedly installed on the outer wall of the steel sleeve 2. The left end of the first stiffening plate 205 is fixedly connected to the right side wall of the first circular ring plate 201, and the right end of the first stiffening plate 205 is fixedly connected to the left side wall of the fourth circular ring plate 204; the left end of the second stiffening plate 206 is fixedly connected to the right side wall of the fourth circular ring plate 204, and the right end of the first stiffening plate 205 is fixedly connected to the left side wall of the second circular ring plate 202.

[0028] It should be noted that the left bottom of the first stiffening plate 205 has a groove to facilitate the installation of bolts on the first circular ring plate 201. The right bottom end of the first stiffening plate 205 is provided with an inclined edge, and the right bottom end and the left bottom end of the second stiffening plate 206 are both provided with inclined edges, and the inclined edges replace the original sharp corners.

[0029] In this embodiment, in combination with Figure 1 As shown in the figure, a rubber curtain 4 is installed on the right side of the second circular ring plate 202, a third circular ring plate 203 is installed on the right side of the rubber curtain 4, and a fixing plate 5 is installed on the right side of the third circular ring plate 203. A flap 501 is hinged at the bottom of the fixing plate 5. When fixing, the double-headed bolt passes through the second circular ring plate 202, the rubber curtain 4, the third circular ring plate 203, and the fixing plate 5, and the double-headed bolt firmly fixes the second circular ring plate 202, the rubber curtain 4, the third circular ring plate 203, and the fixing plate 5. And as Figure 1 As shown in the figure, a third stiffening plate 502 is installed on the right end face of the fixing plate 5. The third stiffening plate 502 extends downward. The left side of the third stiffening plate 502 has a groove for accommodating the hinge joint, so that the vertical length of the lower end of the third stiffening plate 502 coinciding with the flap 501 is 20 mm, preventing the flap 501 and the rubber curtain 4 from flipping.

[0030] In some implementation manners of this embodiment, in combination with Figure 1 and Figure 3 As shown in the figure, two circular brushes 3 are installed inside the steel sleeve 2. The circular brush 3 includes two parts: a fixed head 302 and an annular brush hair 301. The right end of the annular brush hair 301 is inserted into the horizontally placed U-shaped fixed head 302 for fixation, and the annular brush hair 301 extends horizontally to the left by a certain distance from the fixed head 302, and then the end of the annular brush hair 301 extends towards the center of the steel sleeve 2 and the portal side (left side).

[0031] In combination with Figure 3 As shown in the figure, the outer bottom end to the inner bottom end of the annular brush hair 301 gradually approaches the steel sleeve 2 to ensure that the bending degrees of all the annular brush hairs 301 are as consistent as possible after the shield machine enters.

[0032] It should be noted that as Figure 3 shown, the inner side of the annular brush bristles 301 is 450 mm long, the included angle between the inner side and the horizontal line is 55°, and the outer side is 390 mm long. The bottom plate connecting the fixed head 302 and the steel sleeve 2 is made of Q235B steel. The spring steel plate for fixing the annular brush bristles 301 by the fixed head 302 is of 65Mn type. After heat treatment, the hardness is not less than 45±2 HRC. The annular brush bristles 301 are made of 0.35 stainless steel wire, the material is 201 stainless steel, and the hardness requirement is 550 HV~600 HV in Vickers hardness.

[0033] When installing the ring brush 3, first draw a line for positioning the installation position of the ring brush 3 in the steel sleeve 2 according to the design drawing. The grease filling hole 207 should be located between the two ring brushes 3 to ensure that grease can be filled. Spot-weld the finished ring brush 3 according to the marked position. After all positioning is completed, weld the ring brush 3 and the steel sleeve 2 in a circular full-weld along the inner circle to ensure that the ring brush 3 is firmly fixed.

[0034] After the steel sleeve 2 is processed, it is assembled on a flat ground for trial assembly. Only after the assembly is qualified can it enter the construction hole 1 for installation, and the ovality of the whole circle is required not to be higher than 5‰.

[0035] The installation method and sealing treatment are as follows: Installation of the steel sleeve 2: Use a truck crane to hoist the steel sleeve 2 into the well for installation. After the overall installation is completed, repeatedly tighten the bolts connecting between the parts to ensure firm installation. After the installation and re-tightening are completed, weld the gaps of the bolt connections inside and outside, and the weld height is hf = 8 mm (double-sided) to ensure the airtightness of the whole circle of the steel sleeve 2.

[0036] Installation of the rubber curtain 4: The rubber curtain 4 is a whole-ring rubber ring. Before installation, first install the screw rod of the bolt in place to prevent the rubber curtain 4 from slipping. Then install the rubber curtain 4 on the steel sleeve 2 one by one according to the distribution of the bolt holes.

[0037] Installation of the ring plate: The ring plate one 201, the ring plate two 202, the ring plate three 203, and the ring plate four 204 are each divided into 4 pieces, and the 4 ring plates are connected into a whole by welding.

[0038] Installation of the folding flap 501: The folding flap 501 is a single piece. It is installed on the steel ring of the fixed plate 5 of the portal one by one by manual installation by aligning the bolts, and then the nuts are tightened, and the portal sealing structure is installed.

[0039] Grease application to the ring brush 3: Apply grease to the two circular brushes 3. Manually apply shield tail grease (the same as the shield tail grease application for the shield tail brushes of the shield machine). When applying the shield tail grease, separate the steel wires of the annular bristles 301 and apply the grease to the bottom of the circular brush 3 to ensure that the grease in the circular brush 3 forms a closed loop. The annular bristles 301 should be fully filled, and the application between each layer of circular brushes 3 should be dense without gaps.

[0040] Inject grease between the circular brushes 3: After the installation of the entire sealing structure is completed, the shield can be launched and the negative ring segments can be assembled. Push the cutter head of the shield machine to the face of the construction opening 1 and then stop the machine (without breaking the portal). At this time, inject shield tail grease into the cavity between the circular brushes 3. Connect the grease pumps to the 8 grease injection holes 207 simultaneously to inject grease, fill the space between the circular brushes 3, and observe the grease pressure at the same time. The grease injection can be ended when the grease pressure at each point reaches 3 bar (taking the buried depth of the tunnel during the initial launch of a conventional shield as 10 - 15 m as an example).

[0041] After the grease injection between the circular brushes 3 is completed and the grease pressure meets the requirements, conduct a pressure holding test to check the overall sealing effect of the sealing structure. Inject full - bin bentonite slurry in front of the cutter head (the injection volume is calculated based on the size of the shield machine and the volume of the soil chamber). It is required that the bin should be more than 95% full (ensuring that the soil chamber pressure can reach above 1.2 bar), and the viscosity of the bentonite slurry should not be too thick, and it is appropriate to control the viscosity at 40 s.

[0042] Judgment criteria: (1) In the pressure resistance test, the soil chamber pressure needs to be increased to above 1.2 bar and the basic chamber pressure should be kept stable to meet the requirements of building pressure and tunneling during the initial launch of the shield into the tunnel. (2) There should be no leakage points of bentonite slurry in the entire sealing structure. If there are any, additional shield tail grease should be injected at the leakage points of the steel sleeve 2 until there is no more leakage.

[0043] (3) If the soil chamber pressure is basically stable and the pressure drop does not exceed 0.1 bar / 2 h, it can be determined that the sealing effect of the entire sealing structure meets the requirements.

[0044] After the pressure holding test is completed, the shield cutter head can start to break through the portal and tunnel. During tunneling, key control of the tunneling parameters is required.

[0045] Setting of tunneling parameters (taking the Φ8840 mm shield machine as an example): When initially launching into the tunnel, the relative position of the cutter head entering the tunnel should be strictly measured, and the tunneling parameters should be adjusted in a timely manner. Especially after breaking through the portal and entering the formation, a sufficiently stable speed should be maintained for continuous tunneling, quickly advancing the entire shield machine into the tunnel, and completing the work of sealing the portal. Therefore, the subsequent entry of the shield machine into the tunnel can be divided into three stages: the cutter head breaks through the diaphragm wall of the portal, the cutter head enters the formation, and the shield tail enters the formation.

[0046] Cutter head breaking through the diaphragm wall of the portal: At this time, the cutter head gradually breaks through the fiberglass bars of the portal. The tunneling speed should be slowed down and the thrust should be reduced to avoid deformation of the reaction frame caused by excessive thrust. The construction parameters are shown in the following table: Cutter head entering the formation: At this time, the cutter head breaks through the portal and enters the formation. The thrust should be increased (pay attention to observing the stress condition of the reaction frame), the tunneling speed should be increased, and the muck discharge volume should be appropriately reduced. Gradually build up the soil chamber pressure to maintain the stability of the working face. It is normal that the torque of the cutter head in the reinforced body may be slightly higher. Keep tunneling quickly and continuously to make the shield body enter the formation as soon as possible. The construction parameters are shown in the following table: Tail shield entering the formation: At this time, the whole shield machine enters the formation. The portal should be sealed in time. The portal sealing can be carried out in two ways: process grouting + stop grouting. Start grouting while tunneling after the tail shield begins to enter the side wall of the station. Synchronous grouting should be carried out during the tunneling process (inject slowly, and the pressure should not be too high). After the tail shield enters the formation for 1m - 2m, stop grouting at the portal (the tail shield should be far enough from the portal to avoid the slurry around the tail shield during portal sealing). The construction parameters are shown in the following figure: Soil chamber pressure control: Cutter head breaking through the diaphragm wall of the portal: When starting the shield tunneling after the pressure test, maintain the full - bin bentonite slurry level in the soil chamber and carry out slow tunneling, mainly controlled by the earth pressure. Ensure that the soil chamber pressure is not less than 1.1 bar and gradually discharge soil, release and reduce the discharge volume, increase the solid slag content in the soil chamber, and convert from the slurry chamber to the solid soil chamber (calculated according to 1m of the diaphragm wall. When the cutter head breaks through the portal, more than 60% of the solid soil chamber position in the soil chamber should be replaced).

[0047] Cutter head entering the formation: Maintain the bin level unchanged and carry out tunneling by the method of pressure - holding to continue building up the solid soil level in the soil chamber, so that the soil pressure is gradually built up to more than 1.4 bar to ensure the stability of the sand layer working face.

[0048] It should be noted that: When the cutter head passes through the formation reinforcement section and enters the conventional formation, the establishment of the soil chamber pressure should be completed (appropriately overpressure by 0.1 - 0.2 bar according to the pressure value set according to the tunnel burial depth). Muck improvement: Based on the construction experience in water - rich sand layers, the muck improvement method mainly uses foam agent supplemented by bentonite. The set parameters of the foam agent can be: the original liquid ratio is 3%, and the foam dispersion coefficient is 1:12 - 1:13; the set parameters of bentonite can be: the mass ratio is 1:8, the external admixture amount is 8% - 10%, and the fermentation viscosity is not less than 60 s.

[0049] Supplementary injection of portal seal grease: During the shield starting and entering the hole, in addition to the conventional injection of tail shield grease, the grease injection into the grease chamber of the ring brush 3 should be maintained at all times, and the pressure at each grease injection point should not be less than 3 bar to ensure the sealing structure effect.

[0050] After the tail shield of the shield machine enters the formation by 1 - 2 m, stop the machine and seal the portal. The sealing is carried out with double - liquid grout. The main position for grouting is the grouting holes of the steel sleeve 2, supplemented by the grouting holes of the segment. After the entire portal sealing meets the requirements, it represents the completion of the shield starting and entering the tunnel work. Embodiment

[0051] This embodiment proposes a starting construction method for an earth pressure balance shield machine, and further optimizes it mainly for the annular brush bristles 301 in this embodiment.

[0052] Combined with Figure 4 As shown, in this embodiment, the annular brush 3 is composed of a pair of fixed heads 302, annular brush bristles 301, and elastic strips 303. Among them, the elastic strip 303 is connected to the left fixed head 302. The elastic strip 303 and the annular brush bristles 301 are nearly symmetrical, and the bottom end of the annular brush bristles 301 is connected to the bottom end of the elastic strip 303. The middle part of the elastic strip 303 is bent into a V - shape to form a V - shaped elastic part 304. The elastic strip 303 and the V - shaped elastic part 304 have good elastic support for the bottom end of the annular brush bristles 301, making the supporting force of the annular brush bristles 301 against the outer wall of the shield machine stronger and having a better sealing effect.

[0053] Furthermore, since manual application is used when applying tail shield grease, it is necessary to separate the annular brush bristles 301 and apply it densely from the root. When applying manually, apply the grease from the right side of the annular brush bristles 301, and then brush along the annular brush bristles 301 with the hand. Due to the fluidity of the grease, a considerable part of the grease will emerge from the left side of the annular brush bristles 301, which is likely to cause relatively large waste. And when applying the grease, the hand applies force to the annular brush bristles 301 from one side, and some of the steel wires in the annular brush bristles 301 may be deformed, affecting subsequent grease application. Therefore, in this embodiment, an annular airbag 6 is also installed, which is used in cooperation with the V - shaped elastic part 304 to adjust the supporting force for the annular brush bristles 301. The annular airbag 6 is installed between the elastic strip 303 and the annular brush bristles 301. An air nozzle 601 is installed at the top of the annular brush bristles 301, and the air nozzle 601 passes through the steel sleeve 2 and is connected to an air pump, and the air pump controls the supply or extraction of gas into the annular airbag 6.

[0054] In this embodiment, combined with Figure 4As shown in the figure, the cross-section of the annular airbag 6 is triangular. The left side of the annular airbag 6 abuts against the elastic strip 303, the right side abuts against the annular brush bristles 301, and the top surface abuts against the steel sleeve 2. When applying grease, the annular airbag 6 is inflated and expanded, pressing against the left side of the annular brush bristles 301, reducing the grease from oozing out from the left side of the annular brush bristles 301, thereby reducing waste. Since the annular airbag 6 has a certain supporting effect on the annular brush bristles 301, the steel wire of the annular brush bristles 301 is not easily deformed, and it is more convenient to apply, and it is easier to apply densely. And when the shield machine enters at the start, the annular airbag 6 can be deflated, making the annular brush bristles 301 easy to deform, facilitating the entry of the shield machine. After the shield machine enters, the annular airbag 6 is inflated again, and the V-shaped elastic part 304 is used to adjust the supporting force of the annular brush bristles 301 on the outer wall of the shield machine, making it more flexible to use.

[0055] In summary, the starting construction method of the earth pressure balance shield machine of the present invention has the beneficial effects of easy installation, good sealing performance, and strong pressure-bearing capacity.

[0056] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above description is only the specific embodiments of the present invention and is not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for starting construction of an earth pressure balance shield machine, characterized in that: Including the following methods, S1. Reinforce the construction opening (1) to ensure soil stability when the shield tunnel breaks into the ground. After reinforcement, core sampling is used to test the uniformity and self-sustaining property of the soil after reinforcement. S2, customizing a steel sleeve (2) according to the size of the construction hole (1), wherein a circular brush (3) is arranged inside the steel sleeve (2), wherein the circular brush (3) has circular bristles (301) with the ends extending toward the hole entrance side, and wherein the steel sleeve (2) is provided with a grease filling hole (207), wherein the grease filling hole (207) is located between two circular brushes (3), wherein the inner length of the circular bristles (301) is greater than the outer length of the circular bristles (301), and the outer bottom end to the inner bottom end of the circular bristles (301) gradually approaches the steel sleeve (2); S3, install the steel sleeve to the construction hole, and then install the grouting pipe; S4. Seal the construction opening and perform pressure test after sealing; S5. The shield machine starts excavation construction.

2. The starting construction method of the earth pressure balance shield machine according to claim 1, characterized in that: A circular plate 1 (201) connected to the embedded steel ring (101) is disposed at one end of the steel sleeve (2), and a circular plate 2 (202) is disposed at the other end of the steel sleeve (2). A rubber curtain (4), a circular plate 3 (203) and a fixing plate (5) are sequentially disposed on the outer side of the circular plate 2 (202), and the fixing plate (5) is rotatably connected to a flap (501).

3. The starting construction method of the earth pressure balance shield machine according to claim 2, characterized in that: The middle sleeve of the steel sleeve (2) is provided with a circular ring plate four (204), the outer wall of the steel sleeve (2) is connected with a stiffening plate one (205) whose two ends are respectively connected to the circular ring plate one (201) and the circular ring plate four (204), the outer wall of the steel sleeve (2) is also connected with a stiffening plate two (206) whose two ends are respectively connected to the circular ring plate four (204) and the circular ring plate two (202), the inner end of the fixed plate (5) extends into the hole of the steel sleeve (2), the outer wall of the fixed plate (5) is provided with a stiffening plate three (502), and the stiffening plate three (502) extends to the flap (501).

4. The starting construction method of an earth pressure balance shield machine according to claim 1, characterized in that: The annular brush (3) further comprises a fixed head (302), two of the fixed heads (302) being connected to the steel sleeve (2), one of the fixed heads (302) being connected to the annular bristles (301), and the other of the fixed heads (302) being provided with an elastic strip (303) connected to the end of the annular bristles (301), and the elastic strip (303) being provided with a V-shaped elastic portion (304).

5. The starting construction method of an earth pressure balance shield machine according to claim 4, characterized in that: The annular bristles (301) and the elastic strip (303) mounted on the steel sleeve (2) are provided with an annular airbag (6), the cross section of the annular airbag (6) is triangular, the annular airbag (6) is connected to an air nozzle (601), the air nozzle (601) is connected to an air pump, and the air pump controls the degree of tightness of the annular airbag (6) against the annular bristles (301) to meet different support requirements of the annular bristles (301) during grease application and initialization.

6. The starting construction method of an earth pressure balance shield machine according to claim 5, characterized in that: In step S4, grease is applied to the two circular brushes (3). When applying, the annular bristles (301) are separated to apply the grease to the bottom of the circular brush (3). The grease is applied densely without leaving any gaps, so as to ensure that the grease in the circular brush (3) forms a closed loop.

7. The starting construction method of an earth pressure balance shield machine according to claim 1, characterized in that: The reinforcement treatment in S1 includes double-tube rotary jet piles. Double-tube rotary jet piles are used in the stratum on one side of the tunnel portal. The width is at least 3m on each side of the tunnel structure, and the depth is not less than 1m from the ground to the bottom of the tunnel. The reinforcement material used is cement slurry with a water-cement ratio of 1.0 to 1.

5.

8. The starting construction method of an earth pressure balance shield machine according to claim 1, characterized in that: The reinforcement treatment in S1 includes WSS ground vertical grouting reinforcement. Grouting holes are arranged in the form of plum blossom piles with a spacing of 1.0m on one side of the tunnel portal. The width is at least 3m outside the tunnel structure edge and the depth is not less than 1m from the ground to the bottom of the tunnel. The reinforcement material used is cement-water glass double liquid slurry with a volume ratio of 1:

1.

9. The starting construction method of an earth pressure balance shield machine according to any one of claims 7-8, characterized in that: The core sampling test in S1 meets the requirement that the permeability coefficient is less than 1.0×10-5cm / s. Several horizontal holes are drilled at the construction opening (1), and the water flow rate of each hole does not exceed 20L / h.

10. The starting construction method of an earth pressure balance shield machine according to claim 1, characterized in that: Twelve grouting holes are arranged on the outside of the steel sleeve (2), four of which are used as main grouting holes (208) for connecting to the grouting pipe, and the remaining eight are used as grease filling holes (207) for injecting grease into the shield tail during the process. The grease filling holes (207) are all independently connected to a grease injection pump.

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