CN108661655B - Large-section U-shaped earth pressure balance shield tunnel construction method based on U-shaped shield machine - Google Patents

Abstract

A large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on a horseshoe-shaped shield machine adopts the following steps, step 1: set up a shield starting device for a reaction force structure in the open hole, and use a large pipe shed to reinforce the end in the direction of entering the hole . Step 2: Set the starting base on the base plate structure, set 3 first guide rails on the starting base as the guide rails of the shield machine, lay 3 second guide rails in the guide hole of the cave door, connect the first guide rail and The second guide rail is connected and located at the connection between the shield tail of the shield machine and the middle shield, and a shield tail welding groove is arranged on the starting base. Step 3: Set the Myeongdong reinforcement section structure to provide reaction force for the shield machine. On the basis of the large-section horseshoe-shaped shield machine, a complete set of technologies for large-section horseshoe-shaped shield construction has been formed: the starting technology of the Myeongdong reaction force structure shield; the control technology of the shield tunneling parameters; the large-section horseshoe-shaped shield segment assembly technology; Muck improvement technology.

Description

A large-section horseshoe-shaped earth pressure balance shield tunnel construction based on a horseshoe shield machine work method

technical field

The invention relates to the field of tunnel construction, in particular to a large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on a horseshoe-shaped shield machine.

Background technique

At present, in the construction of large-scale railway tunnels, the mining method is the main method, supplemented by a small amount of TBM and the shield method, of which the shield method is mainly used to penetrate rivers, straits and urban soft soil layers. When the railway mountain tunnel passes through the sandy and new loess strata, the mining method construction requires auxiliary construction methods and high stiffness support, which is costly, while the shield method is more convenient for construction, the structure is mainly single-layer prefabricated segment, no The additional construction support cost has obvious advantages, but it also needs to increase the initial mechanical research and development and manufacturing costs. In terms of section form, conventional shields are mainly circular, especially when facing the form of double-line large sections, most of them are large-section circular shields. There are also international precedents for the use of double-circle or even three-circle earth pressure balance shields, but there are disadvantages such as increased excavation section, poor stress effect and increased supporting members. As a result, the concept of developing a large-section horseshoe-shaped shield for the construction of a double-track loess-strata railway tunnel was born. Since the construction of a large-section horseshoe shield with multiple cutter heads is an unprecedented attempt, there are the following difficulties or unsolved problems:

(1) The railway mountain tunnel project is different from the departure of the conventional subway shield in the station. The general entrance is a road cutting, and the Myeongdong structure can be fully utilized to replace the special reaction frame for the initiation of the shield used in the conventional subway to provide reaction force.

(2) The key of shield tunnel construction is to determine the tunneling parameters of the shield tunneling machine in a timely and accurate manner according to the geological conditions of tunneling, especially for the construction of a large horseshoe-shaped shield tunnel. Whether the tunneling parameters of the shield tunneling machine are properly determined or not is directly related to the shield tunnel. progress, safety and quality of construction.

(3) The assembly of the horseshoe-shaped segment is one of the design difficulties of the horseshoe-shaped shield machine, and it is also a difficulty in the construction of the shield. Also, because the horseshoe-shaped section does not have the advantage of circular center symmetry, the inner surface of each segment has the characteristics of variable curvature, large weight, large inertia, and offset center of gravity, etc., so that the fine-tuning work during the installation of the segment is heavy, and the segments are misaligned. There are many problems such as many connection phenomena, and the circumferential compression force of the wedge-shaped block is not easily transmitted during the final assembly.

(4) In view of the large horseshoe-shaped cross-sectional area, the simultaneous excavation of the nine cutter heads, the uneven mixing effect, and the existence of a mixing blind area, there is a great unevenness in the improvement of the slag, which has a great influence on the direction control of the shield body (attitude). Therefore, it is very important to ensure the improvement of the muck. Through the improvement of the muck, the muck can achieve a real injection molding shape.

(5) Horseshoe-shaped shield with super large cross-section, the tunnel mainly passes through the new loess stratum with full cross-section. The tunnel has a large cross-sectional area and a large amount of synchronous grouting. The stability of the segment after the segment comes out of the shield tail directly affects the quality of the formed tunnel. Because the traditional secondary grouting uses a double-liquid slurry of water glass and cement slurry, a minimum of 4 people can be required for each application. The process is cumbersome and time-consuming, and the phenomenon of pipe blocking and shielding often occurs. In addition, the large-section horseshoe-shaped shield has a large section, and the weight of the segment structure and the buoyancy of the slurry are large. The improper performance and operation of the synchronous grouting slurry can easily cause hidden dangers such as segment cracking.

(6) During the excavation, the 3#, 5#, and 7# cutterheads are in front, and a blind zone is formed between the 1#, 4#, and 6# rear cutterheads. Blind area, the accumulation of muck in the blind area causes the thrust to gradually increase in the sandy old loess layer, which leads to the difficulty of excavation, the resistance between the cutter head and the incision increases, and the soil column in the blind area is difficult to destroy and directly pushes into the clapboard of the soil bin, resulting in the increase of thrust At the same time, there is no speed, and the torque of the cutter head also increases.

(6) The entrance of the railway mountain tunnel is generally a cutting, which is different from the receiving of the conventional subway shield in the station. Therefore, the receiving construction needs to be combined with the slope of the tunnel entrance and the structure of the open hole. The road cutting open hole receiving technology adopts the retaining wall to support the inclined slope instead of the conventional rotary jetting or pile reinforcement at the entrance section, which solves the problem of the stability of the side slope; The problem of machine receiving and dismantling is solved; the joint construction measures solve the connection problem between the segment structure and the Myeongdong section.

Therefore, the construction of large-section horseshoe-shaped shield is a new thing, which is very different from the conventional small-section special-shaped shield or large-section circular shield construction. This construction method patent is comprehensively formed on the basis of addressing the above-mentioned construction difficulties and new problems.

SUMMARY OF THE INVENTION

Aiming at the deficiencies of the prior art, the present invention proposes a large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on a horseshoe-shaped shield machine. The specific technical scheme is as follows:

A large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on a horseshoe-shaped shield machine is characterized in that: the following steps are adopted:

Step 1: Set the starting device of the shield machine, and use a large pipe shed to reinforce the end toward the hole.

Step 2: A starting base (11) is set on the bottom plate structure (10), three first guide rails are set on the starting base (11) as guide rails for the shield machine, and three are laid in the guide hole of the tunnel door The second guide rail (12) connects the first guide rail and the second guide rail and is located at the connection between the shield tail of the shield machine and the middle shield, and a shield tail welding groove (13) is arranged on the starting base.

Step 3: Setting the Myeongdong reinforcement section structure (14) to provide reaction force for the shield machine.

Step 4: Set up the sealing device of the tunnel door, construct the starting guide hole in the direction of the entrance of the sleeve arch, connect the exit end of the starting guide hole with the sleeve arch, weld the first embedded steel ring at the entrance end, and install the first embedded steel ring on the first pipe. After the piece comes out of the shield tail, it is closed by the gap between the first segment and the sleeve arch, and the iron sheet is arranged to close the gap between the arch of the starting guide hole and the segment, and at the same time, a support is installed in the arch;

Step 5: The shield machine (5) starts to work and excavate, and during the entire excavation process of the shield machine (5), the A material and the B material are used for simultaneous grouting;

At the same time, every time the shield machine (5) excavates a certain distance in the tunnel, the horseshoe-shaped shield segment is assembled at the shield tail of the shield machine (5);

At the same time, during the whole excavation process of the shield machine (5), the pressure in the soil bin is controlled to be stable and balanced in real time.

Step 6: Receive the shield machine (5).

For better realization of the present invention, it can be further:

In the step 5, during the entire shield tunneling process, the synchronous grouting of material A and material B includes the following steps:

Step S1: According to the relationship between the grouting amount and the disturbed stratum range when the shield machine is excavating, the filling coefficient is determined to be 1.3-1.8;

Step S2: Add material A directly during mixing in the mixing station, replace the cement in the synchronous grouting mortar with the same quality, and introduce material B into the storage tank after dissolving in the hole.

Step S3: Renovate the synchronous grouting pipeline at the tail of the shield machine, fully mix the B solution with the mortar containing the A material at the tail of the shield machine, and accurately control the injection amount and pressure through the metering pump.

Step S4: After solidifying for a period of time, the proportion of AB material changes according to the change of the cement content in the mortar ratio, and the initial setting time can be controlled by adjusting the proportion of the two materials.

Further: when the shield machine is excavating, the cutter head is modified, and the No. 5 cutter head (16) and the No. 6 cutter head (17) are excavated by 300mm on each side, and the No. 1 cutter head (18) in the middle needs to be replaced. The knife beam is cut off, and then the gap of the knife beam is sealed with a sealing plate.

Modification of No. 5 cutter head (16): lengthen the cutter beam; weld the cutter on the cutter beam; cut off the five-sided oblique beam in the center, and weld a new oblique beam;

Modification of the No. 1 cutter head (18): cut off the interfering cutter beam, plug the foam tube, and seal the gap of the cutter beam;

The No. 4 cutter head (19) and No. 6 cutter head (20) are modified, the cutter beam is lengthened, the scraper is welded on the cutter beam, and the No. 4 cutter head (19), No. 5 cutter head (16) and No. 6 cutter head are added. (20) excavation diameter.

A conical ballast divider is added at the bottom of the soil bin to destroy the hardened soil body on the face here, and a high-pressure water pipe is installed in the blind area of the cutter head.

Further: the step 6 includes the following steps:

Take the following steps,

Step 61: Apply the slope of the eight-character retaining wall to support the edge on both sides of the hole ring;

Step 62: Determine the time to start cutting the tunnel door according to the tunneling situation of the shield machine and the requirements of the receiving process, and prepare to cut the tunnel door;

Step 63: chisel the hole door First, set up steel scaffolding within the scope of the hole door steel ring (2) on the receiving base (1), take root in the receiving base (1), and connect with the receiving retaining walls (3) on both sides. set up as a whole;

Pad the lower part of the scaffolding, connect the two sides of the scaffolding to the retaining wall and fasten them respectively, and lay wooden boards on the horizontal braces and fix them with the horizontal braces;

Five observation holes are evenly distributed on the top, middle and bottom of the tunnel door, and the soil condition behind the end wall can be observed at any time. When the cutter head is 50cm away from the end wall (4), the shield operator reduces the soil bin pressure to 0, and immediately takes pulverization measures. The 30cm-thick plain concrete within the range of the steel ring (2) of the tunnel door is chiseled by the method of natural chiseling.

Step 64: Execute the shield machine (5) to receive once, and judge whether the concrete at the tunnel door is chiseled, if so, go to the next step, otherwise, go back to step 63;

Step 65: dismantle the scaffold, push the shield machine within a specified time, stop the injection of the synchronous slurry, and stop the rotation of the cutter head (6) before the cutter head (6) reaches the extension guide rail of the base;

Step 66: Cut an uphill gap on the extended guide rail along the tunneling direction of the shield machine (5). When the shield tail reaches the specified distance from the hole (7), the first exit is completed, and the shield machine stops advancing. In the gap between the steel ring (2) of the tunnel door and the outer casing of the shield machine (5), a whole circle of arc-shaped steel plates is welded by segment welding to seal the hole ring, and the steel plate reserved for the grouting pipe is welded to the corresponding Position, the gap between the arc-shaped steel plate and the shield shell and the steel ring is filled with quick-setting cement. After the sealing is completed, grouting is performed on the building gap outside the shield segment in the reinforcement area, and the third ring away from the shield tail is pressed. Inject two-liquid cement slurry or directly fill the shield tail by synchronous grouting with AB liquid;

Step 67: After the grouting work is completed, open the hole to check the solidification effect of the slurry. After the slurry is basically solidified, the shield machine (5) starts to receive the second time, and the shield machine (5) climbs the base guide rail and continues to advance;

After the shield tail is completely exposed from the end wall (4), immediately seal the gap between the steel ring (2) of the tunnel door and the shield segment (9) with the sealing steel plate (8), and the sealing steel plate (8) is made in blocks. , welded on the steel ring (2) of the tunnel door after accurate positioning, and the sealing steel plate (8) is fully welded at the steel ring (2) of the tunnel door. The segment (9) is filled with the building gap at the steel ring (2) of the tunnel door;

Step 68: further use the segment grouting hole to grouting the hole to prevent water leakage and create conditions for the stable connection between the end wall (4) and the shield segment (9);

Step 69: After the shield machine (5) is pushed to the predetermined position, the entire receiving work is completed.

Further: During the entire shield tunneling process, the attitude adjustment amount of each ring is controlled within 6mm, the shield axis deviation from the design axis is not more than ±50mm, the ground uplift is controlled within +10mm ~ -30mm, and the starting point is at the starting base. The propelling speed on the seat is controlled at 20-30mm/min, the first 12m of the shield machine entering the undisturbed soil is controlled within 20-30mm/min, and it is gradually increased to 30-40mm/min after the shield tail of the shield machine completely enters the undisturbed soil. min.

Further: in the described step 5, the pressure stabilization balance in the real-time control of the soil bin includes the following steps:

S51: Set the soil pressure value in the soil bin as P, obtain the sum of the hydrostatic pressure and the stratum soil pressure as P0, and satisfy P=K*P ₀ . Two methods of soil volume and adjustment of driving speed should be established, and the balance of cutting soil volume and soil discharge volume should be maintained, so that the pressure in the soil bin can be stably balanced. The above K value is between 1.0 and 3.0;

S52: Use at least one screw conveyor to discharge slag, and at the same time, control the pressure on the left and right sides of the soil bin to achieve earth pressure balance and control the surface settlement.

S53: Add foaming agent and bentonite to the stratum with poor fluidity of sandy soil to improve the water-stopping properties of ballast soil, so as to stabilize and balance the pressure in the soil bin.

S54: According to the geological conditions, the state of the discharged ballast, and the various working state parameters of the shield machine, dynamically adjust the balance of the shield machine’s tunneling speed and the amount of excavation to control the pressure of the soil bin, and adjust the speed by adjusting the speed of the screw conveyor. soil discharge.

The beneficial effects of the invention are as follows: first, on the basis of the large-section horseshoe-shaped shield machine, a complete set of technologies for the construction of the large-section horseshoe-shaped shield is formed: the starting technology of the shield with the reaction force structure in the open hole; the control technology of the shield tunneling parameters; Large-section horseshoe-shaped shield segment assembly technology; slag improvement technology; A and B material synchronous grouting technology; long-distance belt slag removal technology, excavation surface blind area treatment technology, cutting receiving technology.

Second, the Myeongdong reaction force structure shield starting technology not only saves the construction and dismantling costs of the reaction force frame, shaft, starting end wall and negative ring, but also greatly saves the construction cost. In the case of the frame, the reaction frame itself is not easy to fix effectively.

Third, the tunneling parameters of the shield machine ensure the smooth and normal tunneling of the large-section horseshoe shield.

Fourth, the large-section horseshoe-shaped shield segment assembly technology solves the problem of the offset of the center of gravity of the large-section horseshoe-shaped segment, the heavy workload of fine-tuning during installation, the dislocation and overlap of the segments, and the circumferential compression of the wedge-shaped blocks during final assembly. Difficulty in power transmission and many other problems.

Fifth, the problems of large horseshoe-shaped cross-sectional area, uneven mixing effect of nine cutters, blind mixing zones and poor flow plasticity of the slag are solved through the slag improvement technology.

6. The synchronous grouting technology of materials A and B solves the phenomenon of blocking the pipe and locking the shield shell, as well as the problem that the large-section segment is easy to crack under the action of its own gravity and synchronous grouting buoyancy.

7. The long-distance continuous belt conveyor slag removal technology improves the transportation efficiency and improves the environment in the cave.

8. The blind spot treatment technology of the excavation face solves the problem of the formation of blind spots between multiple cutter heads during the excavation, and the accumulation of dregs in the blind spots, which leads to the gradual increase of thrust and the difficulty of excavation. Especially when there is a hard soil or rock formation inconsistent with the geological survey, it is difficult for the soil column in the blind area to be destroyed and directly pushed into the inner clapboard of the soil bin, resulting in increased thrust and torque, making it difficult to excavate.

Description of drawings

Fig. 1 is the structural representation of originating base station;

Figure 2 is the location diagram of the reinforcement section of Myeongdong and the main machine of the shield;

Figure 3 is a layout diagram of the scaffolding erection of the cave door and the receiving base;

4 is a schematic diagram of a sealing device;

Figure 5 is a diagram showing the positional relationship between the shield and the receiving end wall after receiving;

Figure 6 is a schematic diagram of the distribution structure of the modified cutter head.

Detailed ways

The preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, and the protection scope of the present invention can be more clearly defined.

A large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on a horseshoe-shaped shield machine mainly includes the following steps:

Step 1: Set up the shield machine starting device, strengthen the end, and use a large tube shed to strengthen the end in the direction of the large mileage, with a length of 40m. At the beginning of excavation, through the tunnel door sealing device and the pressure maintaining measures during the excavation process, the stability of the stratum at the top of the tunnel can be ensured, and other end reinforcement measures are not required. For the large pipe shed to be constructed, it is necessary to manually detect the horizontal range and depth to ensure that the large pipe shed does not intrude into the tunnel clearance.

Step 2: The installation position of the starting base 11 is based on the baseline of the measured stakeout, and the downhole positioning and construction is performed. The track on the starting base 11 is placed symmetrically in the center of the measured hole door. The starting base 11 has a total length of 24m, a width of 16m, and a height of 3m on both sides of the starting base 11. The shield starting base 11 adopts a C30 reinforced concrete structure, and the bottoms are connected together to form an overall structure. Three 120kg/m first guide rails are set on the starting base 11 as the guide rails of the shield machine 5, the bottom guide rail is centered, and the upper two guide rails 12 are 4.8m away from the center. During the construction of the starting base 11 , the reinforcing bars are planted with the base plate structure 10 to ensure that the starting base 11 and the base plate structure 10 are integrated. Three second guide rails are laid in the guide hole of the tunnel door. The second guide rail is connected with the first guide rail in the starting guide hole, and must be welded firmly to prevent the shield machine 5 from being damaged when it is excavating and affecting the shield machine 5. normal excavation. The position of the guide rail is based on the position corresponding to the extension of the sliding rail of the starting base 11. At the connection between the shield tail and the middle shield, a shield tail welding groove 13 with a width of 800 mm and a height of 700 mm is reserved. There is no guide rail at the shield tail welding groove 13, and the guide rail in front of the shield tail welding groove 13 is sloped.

Step 3: Set the Myeongdong reinforcement section structure 14, the reaction force of the shield is provided by Myeongdong, which replaces the reaction force frame structure in the usual subway shield starting. The reinforcement section 14 in Myeongdong provides the reaction force required for the shield machine to push forward. When the shield starts, the thrust is mainly concentrated in the lower half. Schematic diagrams 1 and 2 of the positions of the reinforcement section 14 in Myeongdong and the shield machine.

Step 4: Install the sealing device of the cave door. In the direction of the sleeve arch towards the entrance of the cave, a 13.5m-long starting guide hole is constructed, and the inner diameter of the arch frame is 15.5cm outside the excavation outline. The outer end of the starting guide hole is connected with the sleeve arch, and the entrance end is welded with a pre-embedded steel ring. After the segment comes out of the shield tail, the tunnel door is sealed as required, that is, the gap between the segment and the sleeve arch is closed. Ensure that the shield is in a sealed state when passing through the arch area. The 1mm iron sheet is used to close the gap between the arch frame and the segment of the shield tunnel. During simultaneous grouting, the closed block is deformed, the iron sheet must be firmly embedded in the shotcrete and one side is close to the arch frame, and the concrete or mortar filling must not be loose and affect the use. During the application process: the longitudinal deviation of the steel ring position is 3mm, which is 5mm lower than the standard deviation.

Step 5: The shield machine 5 starts to work and excavate. During the entire excavation process of the shield machine 5, the attitude adjustment of each ring is controlled within 6mm, the shield axis deviation from the design axis is not more than ±50mm, and the ground uplift is controlled within +10mm~ -30mm, when starting, the propulsion speed on the starting base 11 is controlled at 20-30mm/min, the propulsion speed of the shield machine before entering the undisturbed soil is controlled within 20-30mm/min, and the shield tail of the shield machine 5 is controlled within 20-30mm/min Gradually increase to 30-40mm/min after completely entering the undisturbed soil;

During the entire excavation process of shield machine 5, material A and material B are used for simultaneous grouting;

At the same time, every time the shield machine 5 excavates a specified distance in the tunnel, the horseshoe-shaped shield segment is assembled at the distance of the tunnel;

At the same time, during the entire shield tunneling process, the pressure in the soil bin is controlled in real time to stabilize and balance.

Step 6: Receive shield machine 5;

Step 6 includes the following steps:

Step 61: Apply a figure-eight retaining wall to support the slopes on both sides of the opening ring. The length of the foot of the eight-character retaining wall is 5m, the width is 2m, the length*width of the top of the wall is 1*1m, the height of the wall is 6m, and the bottom is rigidly connected to the receiving base 1;

Step 62: Determine the time to start cutting the tunnel door according to the tunneling situation of the shield machine and the requirements of the receiving process, and prepare to cut the tunnel door;

Step 63: chisel the hole door. First, set up a steel scaffold within the range of the steel ring 2 of the hole door on the receiving base 1, take root in the receiving base 1 and build it as a whole with the receiving retaining walls 3 on both sides;

Pad the lower part of the scaffolding, connect the two sides of the scaffolding with the receiving retaining wall 3 tightly, and lay wooden boards on the cross braces and fix them with the cross braces;

Five observation holes are evenly distributed on the top, middle and bottom of the tunnel door, and the soil condition behind the end wall can be observed at any time. When the distance between the cutter head and the end wall 4 is 50cm, the shield operator reduces the soil bin pressure to 0 and immediately takes pulverization measures. The method of chiseling is to chisel the 30cm thick plain concrete within the range of the steel ring 2 of the tunnel door.

Step 64: Execute the shield machine 5 to receive once, determine whether the concrete at the tunnel door is chiseled, if so, go to the next step, otherwise, go back to step 63;

Step 65: dismantle the scaffold, push the shield within the specified time, stop the injection of the synchronous slurry, and stop the rotation of the cutter head before the cutter head reaches the extension guide rail of the receiving base 1;

Step 66: Cut an uphill gap on the extension guide along the tunneling direction of the shield machine 5. When the shield tail reaches the specified distance from the hole, the first hole exit is completed, and the shield machine 5 stops advancing. The gap between the ring 2 and the shield shell is welded with a whole circle of arc-shaped steel plates to seal the hole ring, and the steel plate with the grouting pipe is welded in the corresponding position. The gap between the rings 2 is filled with quick-setting cement. After the plugging is completed, grouting is performed on the building gap outside the segment in the reinforcement area, and two-liquid cement slurry is injected at the third ring away from the shield tail or directly at the shield tail. Synchronous grouting is used for filling with AB liquid.

Step 67: After the grouting work is completed, open the hole to check the solidification effect of the slurry. After the slurry is basically solidified, the shield machine 5 starts to receive the second time, and the shield machine climbs on the receiving base guide rail 1 and continues to advance;

After the shield tail is completely exposed to the receiving end wall 4, immediately seal the gap between the shield tunnel steel ring 2 and the shield segment 9 with the blocking steel plate 8, and the blocking steel plate 8 is made in blocks, and then welded to the hole door after accurate positioning. On the steel ring 2, the sealing steel plate 8 is fully welded at the steel ring 2 of the tunnel door. After the welding is completed, the shield tunnel segment 9 and the building gap at the steel ring 2 of the tunnel door are welded with slurry within a specified time. filling;

The shield segment 9 is directly spelled out within the range of the receiving end wall 4, and at the same time, the reserved position of the shield tail cutting groove is extended forward for a specified distance accordingly, and the welding groove is 80cm below the ground of the middle track of the base and 80cm wide;

Step 68: Further use the segment grouting hole to grouting the hole to prevent water leakage and create conditions for the stable connection between the end wall and the segment;

Step 69: After the shield machine is pushed to the predetermined position, the entire receiving work is completed.

The assembly and debugging of the shield includes the following: 1. The shield machine assembly site and assembly equipment 2. The layout of the assembly site.

The shield assembly site is divided into three areas: rear supporting trailer storage area, main engine and accessories storage area, and crane placement area.

Shield machine assembly equipment Shield machine assembly equipment: one 250t crawler crane, one 230t door crane, and corresponding spreaders, implements and tools.

The tunneling parameters of the large-section horseshoe-shaped earth pressure shield machine mainly refer to: the rotation speed and torque of the shield machine cutter head; the total thrust of the propulsion cylinder, the stroke difference of each group and the propulsion speed; the setting of the soil bin pressure; the adjustment of parameters such as foaming agent; Shield tail grease, lithium base grease consumption control, etc.

In the step 5, the real-time control of the pressure stable balance in the soil bin includes the following steps:

S51: Set the soil pressure value in the soil bin as P, obtain the sum of the hydrostatic pressure and the stratum soil pressure as P0, and satisfy P=K*P ₀ . Two methods of soil volume and adjustment of driving speed should be established, and the balance of cutting soil volume and soil discharge volume should be maintained, so that the pressure in the soil bin can be stably balanced. The above K value is between 1.0 and 3.0;

S52: Use at least one screw conveyor to discharge slag, and at the same time, control the pressure on the left and right sides of the soil bin to achieve earth pressure balance and control the surface settlement.

Step S6: adding foaming agent, bentonite, etc. to the stratum with poor fluidity of sandy soil to improve the water stoppage of the ballast soil, so as to stabilize the pressure in the soil bin.

S53: According to the geological conditions, the state of the discharged ballast, and various working state parameters of the shield machine, dynamically adjust the balance of the shield machine’s tunneling speed and the amount of excavation to control the pressure of the soil bin, and adjust the speed of the screw conveyor to adjust soil discharge.

When the shield machine is excavating, the horseshoe-shaped shield segment is assembled, including the following procedures and points:

Segment assembly process: Based on the proportional control of the telescoping, rotating and moving functions of the horseshoe-shaped segment assembly machine, the precise positioning of the segment assembly is realized.

Assembly points: When installing the segment, the driver and bolt installer should be in place. First install the bottom segment and connect the longitudinal bolts first; install the remaining segments symmetrically from bottom to top, and install the longitudinal Bolts and annular bolts are connected and tightened; when the capping block is installed, first overlap 1/3, then insert it radially, and slowly push it longitudinally while adjusting the position; Tighten all the bolts by hand; when the shield is excavating, after the last circulating segment is out of the shield tail, use the pneumatic wrench to re-tighten all the longitudinal bolts of the segment ring in time.

In the step 5, during the entire shield tunneling process, the synchronous grouting of material A and material B includes the following steps:

Step S1: According to the relationship between the grouting amount and the disturbed stratum range when the shield machine is excavating, the filling coefficient is determined to be 1.3-1.8;

Step S2: Add material A directly during mixing in the mixing station, replace the cement in the synchronous grouting mortar with the same quality, and introduce material B into the storage tank after dissolving in the hole.

Step S3: Renovate the synchronous grouting pipeline at the tail of the shield machine, fully mix the B solution with the mortar containing the A material at the tail of the shield machine, and accurately control the injection amount and pressure through the metering pump.

Step S4: After solidifying for a period of time, the proportion of AB material changes according to the change of the cement content in the mortar ratio, and the initial setting time can be controlled by adjusting the proportion of the two materials. The initial setting time is about 15 minutes. Among them, the proportion of AB material changes according to the content of cement in the mortar ratio, and the initial setting time can be controlled by adjusting the proportion of AB materials. make adjustments.

According to many tests, the best mix ratio (kg) of the slurry effect is selected in this project:

Cement: fly ash: bentonite: sand: water: material A: material B (dissolved with water 1:1) = 185:350:50:800:460:15:30;

The renovation of earth bins and excavation openings includes the following:

Add a conical ballast divider at the 5 and 7 o'clock positions at the bottom of the soil bin to destroy the hardened soil on the face here;

In order to prevent the ballast soil from accumulating at the lower part of the center rotating shaft of the No. 5 cutter head 16, the No. 10 and No. 11 agitators are cancelled, and a large ballast separator is added in the middle of the original agitator, so that the ballast soil can slip directly to the screw conveyor mouth and ensure smooth unearthed. .

When the shield machine is excavating, the cutter head is modified, and the No. 5 cutter head 16 and the No. 6 cutter head 17 are expanded by 300mm on each side, and the No. 1 cutter head 18 in the middle needs to be cut off. Seal the gap of the tool beam.

No. 5 cutter head 16 transformation: lengthen the cutter beam; weld the cutter on the cutter beam; cut off the five-sided oblique beam in the center, and weld the new oblique beam;

Reconstruction of No. 1 cutter head 18: cut off the interfering cutter beam, plug the foam tube, and seal the gap of the cutter beam;

No. 4 cutter head 19 and No. 6 cutter head 20 were modified, the cutter beam was lengthened, scrapers were welded on the cutter beam, and the excavation diameter of No. 4 cutter head 19, No. 5 cutter head 16 and No. 6 cutter head 20 was increased.

A conical ballast divider is added at the bottom of the soil bin to destroy the hardened soil body on the face here, and a high-pressure water pipe is installed in the blind area of the cutter head.

Use high-pressure water pipes in the blind area of the cutter head, and use high-pressure water to wash the soil in the blind area to disperse and collapse. At the same time, supplemented by muck improvement measures, see the muck improvement section for details.

Claims (5)

1. a large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on a horseshoe-shaped shield machine, is characterized in that: adopt the following steps, Step 1: Set the starting device of the shield machine, and use a large pipe shed to reinforce the end toward the hole; Step 2: A starting base (11) is set on the bottom plate structure (10), three first guide rails are set on the starting base (11) as guide rails for the shield machine, and three are laid in the guide hole of the tunnel door The second guide rail (12) connects the first guide rail with the second guide rail, is located at the connection between the shield tail of the shield machine and the middle shield, and is provided with a shield tail welding groove (13) on the starting base; Step 3: Setting the Myeongdong reinforcement section structure (14) to provide reaction force for the shield machine; Step 4: Set up the sealing device of the tunnel door, construct the starting guide hole in the direction of the entrance of the sleeve arch, connect the exit end of the starting guide hole with the sleeve arch, weld the first embedded steel ring at the entrance end, and install the first embedded steel ring on the first pipe. After the piece comes out of the shield tail, it is closed by the gap between the first segment and the sleeve arch, and the iron sheet is arranged to close the gap between the arch of the starting guide hole and the segment, and at the same time, a support is installed in the arch; Step 5: The shield machine (5) starts to work and excavate, and during the entire excavation process of the shield machine (5), the A material and the B material are used for simultaneous grouting; At the same time, every time the shield machine (5) excavates a certain distance in the tunnel, the horseshoe-shaped shield segment is assembled at the shield tail of the shield machine (5); At the same time, during the entire excavation process of the shield machine (5), the pressure in the soil bin is controlled to be stable and balanced in real time; Step 6: Receive the shield machine (5); The step 6 includes the following steps: Take the following steps, Step 61: Apply the slope of the eight-character retaining wall to support the edge on both sides of the hole ring; Step 62: Determine the time to start cutting the tunnel door according to the tunneling situation of the shield machine and the requirements of the receiving process, and prepare to cut the tunnel door; Step 63: chisel the hole door First, set up steel scaffolding within the range of the hole door steel ring (2) on the receiving base (1), take root in the receiving base (1) and connect with the receiving retaining walls (3) on both sides. set up as a whole; Pad the lower part of the scaffolding, connect the two sides of the scaffolding to the retaining wall and fasten them respectively, and lay wooden boards on the horizontal braces and fix them with the horizontal braces; Five observation holes are evenly distributed on the top, middle and bottom of the tunnel door, and the soil condition behind the end wall can be observed at any time. When the cutter head is 50cm away from the end wall (4), the shield operator reduces the soil bin pressure to 0, and immediately takes pulverization measures. The 30cm-thick plain concrete within the range of the steel ring (2) of the tunnel door is chiseled by the method of natural chiseling. Step 64: Execute the shield machine (5) to receive once, and judge whether the concrete at the tunnel door is chiseled, if so, go to the next step, otherwise, go back to step 63; Step 65: dismantle the scaffold, push the shield machine within a specified time, stop the injection of the synchronous slurry, and stop the rotation of the cutter head (6) before the cutter head (6) reaches the extension guide rail of the base; Step 66: Cut an uphill gap on the extended guide rail along the tunneling direction of the shield machine (5). When the shield tail reaches the specified distance from the hole (7), the first exit is completed, and the shield machine stops advancing. In the gap between the steel ring (2) of the tunnel door and the outer casing of the shield machine (5), a whole circle of arc-shaped steel plates is welded by segment welding to seal the hole ring, and the steel plate reserved for the grouting pipe is welded to the corresponding Position, the gap between the arc-shaped steel plate and the shield shell and the steel ring is filled with quick-setting cement. After the sealing is completed, grouting is performed on the building gap outside the shield segment in the reinforcement area, and the third ring away from the shield tail is pressed. Inject two-liquid cement slurry or directly fill the shield tail by synchronous grouting with AB liquid; Step 67: After the grouting work is completed, open the hole to check the solidification effect of the slurry. After the slurry is basically solidified, the shield machine (5) starts to receive the second time, and the shield machine (5) climbs the base guide rail and continues advance; After the shield tail is completely exposed from the end wall (4), immediately seal the gap between the steel ring (2) of the tunnel door and the shield segment (9) with the sealing steel plate (8), and the sealing steel plate (8) is made in blocks. , welded on the steel ring (2) of the tunnel door after accurate positioning, and the sealing steel plate (8) is fully welded at the steel ring (2) of the tunnel door. The segment (9) is filled with the building gap at the steel ring (2) of the tunnel door; Step 68: further use the segment grouting hole to grouting the hole to prevent water leakage and create conditions for the stable connection between the end wall (4) and the shield segment (9); Step 69: After the shield machine (5) is pushed to the predetermined position, the entire receiving work is completed. 2. be used for the described a kind of large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on the horseshoe-shaped shield machine of claim 1, it is characterized in that: In the step 5, during the entire shield tunneling process, the synchronous grouting of material A and material B includes the following steps: Step S1: According to the relationship between the grouting amount and the disturbed stratum range when the shield machine is excavating, the filling coefficient is determined to be 1.3-1.8; Step S2: Add material A directly during mixing in the mixing station, replace the cement in the synchronous grouting mortar with the same quality, and introduce material B into the storage tank after dissolving in the hole; Step S3: Renovate the synchronous grouting pipeline at the tail of the shield machine, fully mix the B solution with the mortar containing the A material at the tail of the shield machine, and make the injection volume and pressure accurately controllable by the metering pump; Step S4: After solidification for a period of time, the proportion of AB material changes according to the change of the cement content in the mortar ratio, and the initial setting time is controlled by adjusting the proportion of the two materials. 3. be used for the described a kind of large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on the horseshoe-shaped shield machine of claim 1, it is characterized in that: when the shield machine is excavated, the cutter head is transformed, and the No. 5 cutter head is modified. (16) and the No. 6 cutter head (17) are expanded by 300mm on each side, and the No. 1 cutter head (18) in the middle needs to cut off the cutter beam, and then use a sealing plate to seal the gap of the cutter beam; Modification of No. 5 cutter head (16): lengthen the cutter beam; weld the cutter on the cutter beam; cut off the five-sided oblique beam in the center, and weld a new oblique beam; Modification of the No. 1 cutter head (18): cut off the interfering cutter beam, plug the foam tube, and seal the gap of the cutter beam; The No. 4 cutter head (19) and No. 6 cutter head (20) are modified, the cutter beam is lengthened, the scraper is welded on the cutter beam, and the No. 4 cutter head (19), No. 5 cutter head (16) and No. 6 cutter head are added. (20) excavation diameter; A conical ballast divider is added at the bottom of the soil bin to destroy the hardened soil body on the face here, and a high-pressure water pipe is installed in the blind area of the cutter head. 4. be used for the described a kind of large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on horseshoe-shaped shield machine of claim 1, it is characterized in that: in the whole shield tunneling process, every ring attitude adjustment amount is controlled within 6mm , the deviation of the shield axis from the design axis is not more than ±50mm, the ground uplift is controlled at +10mm ~ -30mm, the propulsion speed on the starting base is controlled at 20-30mm/min at the start, and the shield machine enters the undisturbed soil. The 12m propulsion speed is controlled within 20-30mm/min, and gradually increased to 30-40mm/min after the shield tail of the shield machine completely enters the undisturbed soil. 5. be used for a kind of large-section horseshoe-shaped earth pressure balance shield tunnel construction method based on a horseshoe-shaped shield machine according to claim 1, it is characterized in that: in the described step 5, the pressure stabilization balance in the real-time control of the soil bin comprises the following steps : S51: Set the soil pressure value in the soil bin as P, obtain the sum of the hydrostatic pressure and the stratum soil pressure as P0, and satisfy P=K*P ₀ . Two methods of soil volume and adjustment of driving speed should be established, and the balance of cutting soil volume and soil discharge volume should be maintained, so that the pressure in the soil bin can be stably balanced. The above K value is between 1.0 and 3.0; S52: Use at least one screw conveyor to discharge slag, and at the same time, control the pressure on the left and right sides of the soil bin to achieve earth pressure balance and control the surface settlement; S53: Add foaming agent and bentonite to the stratum with poor fluidity of sandy soil to improve the water stoppage of ballast soil, so that the pressure in the soil bin can be stabilized and balanced; S53: According to the geological conditions, the state of the discharged ballast, and various working state parameters of the shield machine, dynamically adjust the balance of the shield machine’s tunneling speed and the amount of excavation to control the pressure of the soil bin, and adjust the speed of the screw conveyor to adjust soil discharge.

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