Under-pressure tool changing construction method for high-water-pressure long-distance shield to penetrate through soft and hard composite stratum

Abstract

The invention relates to the technical field of shield construction, in particular to an under-pressure tool changing construction method for a high-water-pressure long-distance shield to penetrate through a soft and hard composite stratum. Comprising the steps of double plugging (secondary grouting is conducted behind the wall of a segment at the shield tail through double-liquid slurry, and polyurethane is injected into a shield body shell at the middle shield position), tunnel advanced grouting reinforcement, tunnel face mud film retaining wall construction, tool replacement under pressure and pressure reduction and cabin exiting. The construction method has the beneficial effects that secondary grouting is conducted on the wall back of the shield tail segment through cement paste and water glass, polyurethane is injected into a shield body shell in a matched mode to form a closed water stop ring, a double-blocking system is formed, underground water is prevented from moving forwards, a gap between a shield body and surrounding rock is filled, stability of a soil body above a shield is guaranteed, and the construction quality is improved. Secondly, advanced grouting reinforcement and bentonite mud film retaining wall manufacturing are conducted, it is guaranteed that the air pressure in the soil cabin and the water and soil pressure outside the cabin are balanced, and the safety of under-pressure tool changing construction is improved.

Description

Technical Field

[0001] The invention relates to the technical field of shield construction, and in particular to a construction method of a high-water-pressure long-distance shield tunnel that passes through a soft-hard composite stratum and changes cutters under pressure. Background Art

[0002] In a complex and ever-changing geological environment, shield machines face unprecedented challenges in crossing various complex strata with uneven hardness. Some tunnels pass through unfavorable geological conditions such as silty sand, silty clay + limestone, full-section limestone, and areas with strong karst development. In such an environment, shield construction often stops due to excessive wear of the cutter.

[0003] The Chinese invention with publication number CN102758635A discloses a construction method for shield cutting tool changing under pressure in water-rich silt and silt sand strata under railway tracks, which overcomes the risk of sand flow and collapse of water-rich soft soil during shield construction in tunnels in water-rich silt and silt sand strata, and ensures the safe operation of the upper railway.

[0004] However, at present, the traditional pressure-driven cutter replacement construction method is difficult to control the forward movement of groundwater, and the stability of the soil around the shield machine's earth cabin is still insufficient, which poses certain safety hazards. To this end, the present invention proposes a pressure-driven cutter replacement construction method for high-water pressure long-distance shield tunneling through soft and hard composite strata to solve the above problems. Summary of the invention

[0005] The purpose of the present invention is to provide a high-water-pressure, long-distance shield tunneling under pressure with cutter-changing construction method for crossing soft-hard composite strata, so as to solve the problem that the unified cutter-changing construction method under pressure proposed in the above-mentioned background technology is difficult to control the forward rush of groundwater.

[0006] To achieve the above object, the present invention provides the following technical solution: a high water pressure long distance shield tunneling under pressure with cutter change construction method through soft and hard composite strata, which specifically includes the following steps: Step 1: Double plugging: Use double liquid slurry to perform secondary grouting on the wall of the segment at the shield tail, and inject polyurethane into the shield shell at the middle shield; Step 2: Pre-grouting reinforcement of the tunnel: drilling holes in the soil in front of the shield and injecting water-glass double grout; Step 3: Apply mud film to protect the tunnel face wall, inject high viscosity bentonite into the soil tank to form a mud skin to protect the wall; Step 4: Change the cutter under pressure. First, perform air tightness test and gas replacement on the soil compartment, and then coordinate with the robotic arm to change the cutter. Step 5: Decompress and exit the cabin, using multi-stage decompression. Rest sufficiently after each decompression before proceeding to the next decompression, until the pressure difference between the inside and outside of the cabin is zero.

[0007] Preferably, in step one, the components of the double liquid slurry are cement slurry + water glass, with a volume ratio of 1:1, the double liquid slurry grouting position is 4-7 ring segments at the shield tail, the grouting pressure is 0.5 MPa, and after completion, the first closed water stop ring is formed at the shield tail.

[0008] Preferably, in step 1, the polyurethane injection position is located in the area from 11 o'clock to 1 o'clock of the middle shield, filling the gap between the shield body and the surrounding rock to form a second closed water stop ring.

[0009] Preferably, in step 2, the double slurry components are cement slurry + water glass, the volume ratio is 2:1, 3% early strength agent is added to the double slurry, and the grouting pressure is 0.5 MPa.

[0010] Preferably, in step three, high-viscosity bentonite is added from a bentonite system built into the shield machine and filled into the formation.

[0011] Preferably, in step three, after the mud film wall protection is completed, pressurization is performed, and the final pressure is 3.5 bar.

[0012] Preferably, in step 4, the volume content of oxygen in the soil cabin is not less than 20%, harmful gases such as carbon monoxide, methane, hydrogen sulfide, etc. do not exceed the standard, and the gas pressure fluctuation value in the cabin is not greater than 0.05 bar.

[0013] Preferably, in step 4, the staff first enters the auxiliary cabin of the human cabin to eliminate the pressure difference between the main cabin and the auxiliary cabin of the human cabin, then enters the main cabin and pressurizes the main cabin until the pressure of the main cabin and the soil cabin is balanced, and then enters the soil cabin to perform the knife changing operation.

[0014] Preferably, in step 4, the debris attached to the cutter is first cleaned, and when the old cutter is removed, the mechanical arm and guide chain on the top of the soil compartment are used to pull the roller cutter out of the cutter seat and transport it out in relay, and finally replace the new cutter.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention uses cement slurry + water glass to perform secondary grouting behind the wall of the shield tail segment, and injects polyurethane into the shield shell to form a closed water stop ring, forming a double blocking system to prevent groundwater from rushing forward and fill the gap between the shield body and the surrounding rock, thereby ensuring the stability of the soil above the shield. Secondly, advance grouting reinforcement and bentonite mud film wall protection are carried out to ensure the balance of air pressure in the soil cabin and water and soil pressure outside the cabin, thereby improving the safety of pressure-carrying cutter replacement construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall construction process of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose and technical solution of the present invention clearly and completely described, and the advantages more clearly understood, the embodiments of the present invention are further described in detail with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are part of the embodiments of the present invention, rather than all of the embodiments, and are only used to explain the embodiments of the present invention, and are not used to limit the embodiments of the present invention. All other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1 The present invention provides a technical solution: a high-water-pressure, long-distance shield tunneling under pressure with cutter change during traversal of soft-hard composite strata.

[0019] The core of the shield machine's cutter-changing technology under pressure lies in the principle of air pressure balance. First, the soft soil layer in front of the excavation face is reinforced by advance grouting, and then the face is sealed with high-concentration sodium-based bentonite slurry to ensure the air tightness of the shield soil compartment and surrounding strata. Subsequently, pressurized air is injected into the soil compartment through an air compressor to replace the soil, and the water and soil pressure of the excavation face is balanced by air pressure. Under this condition, personnel can safely enter the soil compartment to check and replace the cutters.

[0020] The specific operation points are: 1. Preparation for shield opening: ① Use 1:1 cement slurry + water glass double liquid slurry to carry out secondary grouting on the wall of the 4-7 ring segments of the shield tail, with a grouting pressure of 0.5 MPa to form the first closed water stop ring to prevent groundwater from rushing forward and increase the stability of the formed tunnel; ② Inject polyurethane into the shield shell in the area from 11 o'clock to 1 o'clock in the middle shield to form a second closed water-stop ring, filling the gap between the shield body and the surrounding rock, ensuring the stability of the soil above the shield.

[0021] 2. Tunnel advance grouting reinforcement: ① Use the backward segmented method to drill holes into the soil in front of the shield and inject water-glass double slurry to consolidate the stratum and seal the fissure water in the stratum. The double slurry ratio is 2:1 cement slurry + water-glass, with 3% early strength agent added and the grouting pressure is 0.5 MPa.

[0022] 3. Construction of mud film wall protection on the face of the tunnel: ① Inject high-viscosity bentonite into the soil cabin through the shield bentonite system to effectively fill the stratum cracks and form a thick layer of "wall-protecting mud skin", thereby ensuring the balance of air pressure in the soil cabin and water and soil pressure outside the cabin; ②After the mud film is completed, four levels of pressurization are carried out, each level is 0.2-0.3bar, and the final pressure is 3.5bar. Dynamic pressure maintenance is required during the pressurization process. The first two levels are maintained for two hours, and the last level is maintained for 6 hours. The pressure change during the pressure maintenance process should be less than 0.5bar, otherwise the mud film should be re-applied until it is qualified.

[0023] 4. Soil tank air tightness detection and gas replacement: ① Before personnel enter the cabin, the air tightness of the earth cabin must be tested and the gas in the cabin must be replaced to ensure the safety of the gas environment in the cabin. The volume content of oxygen is controlled at no less than 20% (controlled between 20%-23.5%), and harmful gases such as carbon monoxide, methane, and hydrogen sulfide do not exceed the standard (by volume: carbon monoxide content is not higher than 0.0024%, carbon dioxide content is not higher than 0.5%, methane content is not higher than 1%, and hydrogen sulfide content is not higher than 0.00066%). The gas pressure fluctuation value in the cabin is not greater than 0.05bar.

[0024] 5. Personnel entering the cabin and tool changing operations: ① The personnel shall follow a strict safety entry procedure. First, they shall enter the auxiliary cabin of the man cabin, open the pressure balance valve between the main cabin and the auxiliary cabin of the man cabin, eliminate the pressure difference between the two cabins, then open the sealing door between the main cabin and the auxiliary cabin, enter the main cabin, slowly open the air inlet valve, slowly increase the pressure of the main cabin, and pressurize at 0.5-1bar / 10 minutes per level to a working pressure of 3.5bar, then open the air outlet valve to establish the air inlet and outlet balance of the main cabin. When the pressure of the main cabin is equal to the pressure of the shield earth cabin, open the connecting ball valve between the main cabin and the earth cabin to balance the pressure of the two cabins, and the operators can enter the earth cabin; ② After entering the soil cabin, first clean the debris attached to the cutter, and then determine whether the cutter needs to be replaced according to the wear standard. When removing the old cutter, loosen the nut, pull out the bolt, remove the fixing block, and use the mechanical arm and guide chain on the top of the soil cabin to slide the roller backward, pull out the cutter seat, and then transport it out. When replacing the new cutter, prepare the new cutter in the main cabin of the man cabin, and use a 1.5-ton guide chain to hang it on the longitudinal track of the cabin top beam. Replace the hanging points in turn, transport the new cutter into the soil cabin, and then install the new cutter in the reverse order of removing the old cutter.

[0025] 6. Decompression and exit from the cabin: ① Decompression and exiting the cabin is an important part of ensuring the safety of personnel. The pressure must be gradually reduced in strict accordance with the requirements of the decompression table to ensure the health of personnel. The specific decompression process is: initial 3.5bar-decompression time 5 minutes-2.4bar, rest 5 minutes-decompression time 3 minutes-2.1bar, rest 10 minutes-decompression time 3 minutes-1.8bar, rest 15 minutes-decompression time 3 minutes-1.5bar, rest 20 minutes-decompression time 3 minutes-1.2bar, rest 30 minutes-decompression time 3 minutes-0.9bar, rest 40 minutes-decompression time 3 minutes-0.6bar, rest 45 minutes-decompression time 3 minutes-0.3bar, rest 55 minutes-decompression time 3 minutes-0bar. Staff members need to get enough rest in different pressure environments to ensure their body's adaptation.

[0026] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-water-pressure, long-distance shield tunneling method for crossing soft-hard composite strata with pressure-changing cutters, characterized by: The specific steps include: Step 1: Double plugging: Use double liquid slurry to perform secondary grouting on the wall of the segment at the shield tail, and inject polyurethane into the shield shell at the middle shield; Step 2: Pre-grouting reinforcement of the tunnel: drilling holes in the soil in front of the shield and injecting water-glass double grout; Step 3: Apply mud film to protect the tunnel face wall, inject high viscosity bentonite into the soil tank to form a mud skin to protect the wall; Step 4: Change the cutter under pressure. First, perform air tightness test and gas replacement on the soil compartment, and then coordinate with the robotic arm to change the cutter. Step 5: Decompress and exit the cabin, using multi-stage decompression. Rest sufficiently after each decompression before proceeding to the next decompression, until the pressure difference between the inside and outside of the cabin is zero.

2. The high water pressure long distance shield tunneling under pressure and cutter change construction method for crossing soft and hard composite strata according to claim 1 is characterized by: In the step 1, the components of the double liquid slurry are cement slurry + water glass, the volume ratio is 1:1, the double liquid slurry grouting position is the 4-7 ring segments of the shield tail, the grouting pressure is 0.5 MPa, and after completion, the first closed water stop ring is formed at the shield tail.

3. The high water pressure long distance shield tunneling under pressure and cutter change construction method for crossing soft and hard composite strata according to claim 1 is characterized by: In the step 1, the polyurethane injection position is located in the area from 11 o'clock to 1 o'clock of the middle shield, filling the gap between the shield body and the surrounding rock to form a second closed water stop ring.

4. The high water pressure long distance shield tunneling under pressure and cutter change construction method for crossing soft and hard composite strata according to claim 1 is characterized by: In the step 2, the double slurry components are cement slurry + water glass, the volume ratio is 2:1, 3% early strength agent is added to the double slurry, and the grouting pressure is 0.5 MPa.

5. The high water pressure long distance shield tunneling under pressure and cutter change construction method for crossing soft and hard composite strata according to claim 1 is characterized by: In the step three, high-viscosity bentonite is added from the bentonite system built into the shield machine and filled into the stratum.

6. The high water pressure long distance shield tunneling under pressure and cutter change construction method for crossing soft and hard composite strata according to claim 5 is characterized by: In the step 3, after the mud film wall protection is completed, pressurization is performed, and the final pressure is 3.5 bar.

7. The high water pressure long distance shield tunneling under pressure and cutter change construction method for crossing soft and hard composite strata according to claim 1 is characterized by: In step 4, the volume content of oxygen in the soil cabin is not less than 20%, harmful gases such as carbon monoxide, methane, hydrogen sulfide, etc. do not exceed the standard, and the gas pressure fluctuation value in the cabin is not greater than 0.05 bar.

8. The high water pressure long distance shield tunneling under pressure and cutter change construction method for crossing soft and hard composite strata according to claim 1 is characterized by: In step 4, the staff first enters the auxiliary cabin of the human cabin to eliminate the pressure difference between the main cabin and the auxiliary cabin of the human cabin, then enters the main cabin and pressurizes the main cabin until the pressure of the main cabin and the soil cabin is balanced, and then enters the soil cabin to perform the knife changing operation.

9. The high water pressure long distance shield tunneling under pressure and cutter change construction method for crossing soft and hard composite strata according to claim 1 is characterized by: In the step 4, the debris attached to the cutter is first cleaned, and when the old cutter is removed, the mechanical arm and guide chain on the top of the soil cabin are used to pull the roller cutter out of the cutter seat, relay it out, and finally replace it with a new cutter.

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