Pipe jacking engineering water gushing construction method

Abstract

The application discloses a pipe jacking engineering water gushing construction method, relates to the pipe jacking engineering water gushing construction technical field, and comprises the following steps: S1, surface grouting; S2, water pumping method; S3, hole portal water stop reinforcement; S4, hole opening section anti-pipeline upwarp measure; S5, in-pipe maintenance; S6, wall back grouting; S7, slurry replacement requirement and S8, measurement and deviation rectification construction steps. The pipe jacking engineering water gushing construction method can be favorable for reducing and avoiding pipeline water seepage, thereby guaranteeing normal construction, preventing economic losses and personnel safety hazards caused by equipment flooding, and guaranteeing normal engineering progress.

Description

Technical Field

[0001] This invention relates to the field of water leakage construction technology in pipe jacking projects, specifically a method for water leakage construction in pipe jacking projects. Background Technology

[0002] Pipe jacking is a trenchless construction method, a technology for laying pipelines without excavation or with minimal excavation. In pipe jacking, the jacking force generated by the jacking equipment in the working pit overcomes the friction between the pipeline and the surrounding soil, pushing the pipeline into the soil at the designed slope, and then removing the excavated soil. After one section of the pipe is pushed into the soil, the second section is pushed in to continue jacking. The principle is to use the thrust of the main jacking cylinder and the pipeline and intermediate sections to push the tool pipe or tunneling machine from the working pit through the soil layer to the receiving pit and lift it out. The pipeline follows the tool pipe or tunneling machine and is buried between the two pits.

[0003] In existing pipe jacking construction projects, especially those around reservoirs, water leakage is prone to occur below the pipe during the jacking process. If timely and correct remedial measures are not taken, personnel need to be evacuated urgently. This can easily lead to water entering the pipe jacking machine and flooding of equipment such as water pumps, resulting in economic losses. Therefore, a water leakage prevention method for pipe jacking projects is needed.

[0004] Therefore, in view of this, we have studied and improved the existing structure and its shortcomings, and proposed a method for constructing a water-bearing structure in pipe jacking engineering. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for constructing a pipe jacking project that prevents water from overflowing, thus solving the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for constructing a water-bearing structure in a pipe jacking project, the method comprising the following operational steps:

[0007] S1. Surface grouting:

[0008] Grouting process: Raw material inspection and on-site stacking — Layout of grouting holes — Drilling — Installation of grouting pipes (preparation of grouting materials and testing of grouting equipment) — Inspection of grouting pipes and grouting materials — Grouting. When determining the drilling position, the drilling position is 1.5m on each side of the jacking axis, arranged horizontally with a longitudinal interval of 1m. When drilling, apply light pressure and slow speed to ensure that the hole position does not deviate from the design angle and direction. After drilling is completed, the pipe wall and the hole opening are filled with hemp fiber. After the grouting pipe is installed and checked to be correct, grout is injected into the hole for consolidation. The grouting pipe plays a guiding role.

[0009] S2. Pumping method:

[0010] Pumping was scheduled to begin 6 hours after the completion of the phosphate-water glass double-liquid grouting. To ensure safety and facilitate monitoring of water level changes during pumping, the working well radius was 8 meters, and 200.96 cubic meters of water were pumped out for every 1 meter drop in water level. 3 Choose a 35KW water pump with a flow rate of 160m³ / hour. 3 ;

[0011] The pumping was carried out in three stages. The first stage involved pumping 3 meters of water and observing the water level continuously for 1 hour, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. The second stage involved pumping 3 meters of water and observing the water level continuously for 1 hour, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. The third stage involved pumping 4 meters of water and observing the water level continuously for 2 hours, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. At the same time, a designated person was assigned to observe the water volume in the "channel".

[0012] If the water level does not rise after the test pumping, timely maintenance of the pipe jacking machine should be arranged. If the water level rises significantly after the test pumping, underground cavities should be further explored and the grouting effect should be tested. If there are areas that are not dense, the grouting should be intensified at the tunnel entrance. The grouting range should be expanded to extend 9m to both sides along the central axis, with one hole every 1.5m and a longitudinal spacing of 1m. 4-6 rows of holes should be set, for a total of 36-48 holes. The grouting depth should be 50cm above the top of the pipe to the surface clay layer. Cement grout should be used to form a grouting curtain. The relevant parameters of the grouting process should refer to the method of drilled retaining pile + high-pressure jet grouting pile.

[0013] S3. Waterproofing and reinforcement of the tunnel entrance:

[0014] After grouting is completed and there is no water leakage, the tunnel portal reinforcement work is carried out. Before the portal reinforcement, the pipe is cut, the sealing of the curtain is checked, and the gap between the double-layer curtain is sealed. The construction process of using post-installed double-layer water-stop curtain for reinforcement is as follows:

[0015] Construction preparation → Measurement and positioning → Steel sleeve assembly and fixing → Curtain installation and fine-tuning → Curtain folding → Inspection and acceptance → Concrete pouring.

[0016] Construction preparation: Before construction, two semi-circular interlocking steel collars need to be customized in the factory. The inner diameter of the steel collar is 2580mm, the inner diameter of the curtain is 2000mm, and the outer diameter is 2850mm. The post-installed double-layer water-stop curtain pipe is used to ensure the welding quality. Considering the working surface width and the protection length of the curtain folding rubber during the welding process, the cutting position is determined to be 10cm reserved at the original sleeve opening, with a 60cm interval between the two sleeves. The bevel of the cut pipe is ground into a V-shape.

[0017] Measurement and positioning: The installation position of the steel sleeve is located according to the original center position of the tunnel entrance. Channel steel is used as a temporary external support to stabilize the steel sleeve. The channel steel of the external support is anchored to the original surrounding concrete with protective pads.

[0018] Steel sleeve assembly and fixing: The steel sleeve is hoisted to the measurement and positioning installation position in two stages using a 25t truck crane. The two sections of steel sleeve are connected with M24 bolts and welded firmly to the outer bracket. The assembly error is controlled within ±5mm. The elevation of the steel sleeve is measured and verified. If necessary, the position is finely adjusted by hand hoist. After the verticality is tested and qualified by plumb bob, a "radial" welded fixing frame support is finally formed.

[0019] Curtain installation and fine-tuning: Check the integrity of the rubber curtain, ensure that the bolt hole size deviation meets the installation requirements, and ensure that the φ24 bolt holes on the engineering ring plate are through holes evenly distributed at 9 degrees around the circumference. The bolt hole positions of the two ring plates must be consistent. When stacking two ring plates, ensure that all bolts can pass through the two ring plates at the same time. The curtain is sandwiched between the two ring plates, with the side with the round head facing the direction of travel. The high-strength bolts are temporarily inserted into the bolt holes symmetrically from bottom to top without being tightened. Check the exposed length of the curtain. If necessary, use a hand hoist to fine-tune the position of the curtain to ensure that the error is controlled within ±3mm. After inspection and approval, tighten the bolts symmetrically in sequence.

[0020] Curtain folding: The steel pipe cut is beveled and ground with a V-shaped bevel. After the internal weld of the pipe is completed, the pipe section is pushed in to fold the curtain. Before implementation, grease is applied to the surface of the curtain to prevent the bevel of the pipe section from cutting the curtain. After checking that the bevel is smooth and free of burrs, geotextile is used to temporarily wrap the bevel of the pipe section. Then, the pipe section is slowly pushed in the direction of the curtain at the tunnel entrance. During the pushing, a special person is arranged to check the folding of the curtain. If twisting or other abnormalities occur, the pushing should be stopped immediately and a blunt instrument is used to assist in the folding.

[0021] Concrete pouring: After passing the inspection, install the formwork and pour concrete to encase the water-stopping device and fixing frame of the tunnel entrance, forming a permanent water-stopping tunnel entrance structure. This construction method uses C30 concrete with good workability and a permeability grade of P6. The concrete slump is controlled at 180-220mm. Before pouring, the contact surfaces between the newly poured concrete and the original well wall and bottom slab should be roughened. Concrete should be poured in layers symmetrically, with each layer having a pouring height of 300mm. Considering that it is difficult to vibrate in places, a small hand-held cement vibrator is used for vibration, especially at the junction of the steel components and the tunnel entrance, where manual vibration is used to ensure the structure is dense.

[0022] S4. Measures to prevent pipes from tilting upwards at the opening section:

[0023] To prevent the pipeline tail from tilting upwards due to increased buoyancy after the reservoir and the jacking pipe connect to the ground during the jacking process, a limiting stiffening rib is added between the double-layer curtain fabric. The preferred material is a 45mm thick hard rubber strip, half the outer circumference of the pipe, and 50mm wide. To avoid direct contact between the fixing bolts and the pipeline, tapered bolt holes are used. After the rubber strip is firmly fixed with M16 bolts, the stiffening rib is welded firmly to the steel collar between the two layers of curtain fabric.

[0024] S5. In-pipe maintenance:

[0025] After the water in the pipeline is pumped out, the electrical equipment inside the pipe jacking machine is inspected and repaired. Due to the weight of the electrical equipment, a partition plate is set up during dismantling. The equipment is manually lifted out of the chamber door and transported to the outside of the pipe and then to the outside of the well for repair by handcart. The installation is carried out in the same way.

[0026] S6. Backwall grouting:

[0027] To stabilize the strata, a low-ratio cement-water glass double-liquid grout was injected behind the wall at a position 18m from the tunnel entrance. The specific ratio was determined through experiments based on requirements. Each two pipe sections were grouped together, with injection and discharge holes. The grouting pump was cleaned, and the suction pipe with a valve was placed into the grout pool. The grouting pump was turned on, and the first group of injection holes was opened for grouting. When grout emerged from the first group of discharge holes, the valves were closed, and the second group was opened. This process was repeated until the entire line was completed. Then, all valves were closed, and the pressure was maintained for 20 minutes at 1MPa. Considering the potential structural damage caused by pipe movement during the jacking process, grouting was performed once after each pipe section was jacked.

[0028] S7. Requirements for mud replacement:

[0029] Slurry replacement refers to the immediate replacement of the original bentonite slurry injected into the outer wall of the pipe with hydraulic materials after the completion of a single section of pipe jacking. This creates a high-strength slurry wall on the outer wall of the pipe, capable of withstanding the pressure of the overlying soil and preventing the collapse of the borehole wall. In addition, the addition of an expanding agent to the cement slurry, which has shrinkage-compensating properties, can further reduce the shrinkage of the original slurry, thereby reducing settlement. The replacement slurry for pipe jacking construction is a high-volume fly ash cement slurry made from high-calcium fly ash, cement, and gypsum.

[0030] Replacement principle: Each two pipe sections are grouped together, consisting of grouting holes and grout discharge holes. The grouting pump is cleaned, and the suction pipe with valve is placed into the grout pool. The grouting pump is turned on, and the first group of grouting holes is opened for grouting. When grout emerges from the first group of grout discharge holes, the valve is closed, and the second group is opened. This process is repeated until the entire line is completed. Then, all valves are closed, and the pressure is maintained for 30 minutes at a pressure of 1 MPa.

[0031] After the mud replacement is completed, the main channel grout pipe and the arc-shaped grout pipe inside the pipe section are removed and cleaned on site to prevent the grout from solidifying and clogging, which would affect the later use. After the mud replacement is completed, the grouting hole is sealed: the replacement cement grout on the outside of the grouting hole pipe wall is removed, and the removal range is 5cm around the grouting hole and 1.5cm vertical depth on the pipe wall.

[0032] S8. Measurement and Correction:

[0033] During the pipe jacking construction phase, measurement is crucial. Frequent measurements and timely corrections are essential. It is unacceptable to reduce or omit measurements simply to speed up the process. Generally, measurements should be taken before the pipe is lowered and after the jacking process begins. This allows for easier correction of any deviations detected at these times. During normal jacking, measurements should be taken every 30cm of jacking and again after the entire jacking has progressed 1m. Measurements are conducted using a laser theodolite, with a fixed laser target mounted on the jacking head. The jacking direction of the pipe jacking machine is adjusted promptly based on the data fed back from the laser theodolite and the laser target during the jacking process.

[0034] Planar control: total station, laser theodolite;

[0035] ① To ensure the pipe jacking between the two wells is connected and the lateral and vertical errors are less than 100mm, ground traverse points are buried near the two end wells. Using the empty traverse points and the ground traverse points, the plane control results are transferred to the construction site in the form of traverse surveying.

[0036] A plane control network was established using air traverse points and ground traverse points. The traverse survey was conducted using a total station. Six rounds of direction observations were performed with an angle measurement accuracy of +1. Six rounds of distance measurement were performed with bidirectional observations. The relative error of the distance measurement was <1 / 120000. The observation results were then adjusted.

[0037] ② The transfer of surface coordinates to the underground uses a connecting triangle method, with the points being vertically projected by a laser theodolite;

[0038] Elevation measurement: Laser theodolite;

[0039] ①Using known high-level benchmarks near the construction area, a fourth-order leveling route was set up to transfer the elevation to the vicinity of the working well, and construction elevation control points were established;

[0040] ② When transferring the ground elevation to the well, a steel tape can be suspended vertically with a plumb bob attached to the standard tension. Then, two levels, one on the ground and one in the well, can be used to observe simultaneously. The steel tape should be corrected for both tape length and temperature. Two to three underground starting elevation control points should be set up in the well.

[0041] ③ The elevation control level of the pipe jacking machine head is used to measure the deviation value every 20cm of jacking to keep track of the machine head's posture and development trend in a timely manner so as to correct the deviation in time;

[0042] Jacking posture measurement: In order to ensure that the pipe jacking machine advances strictly according to the design axis, it is necessary to observe the dynamic data of pipe jacking in a timely manner, so as to adjust the various construction parameters of pipe jacking and guide the correct and safe advancement of pipe jacking;

[0043] A pair of horizontal rulers are set longitudinally at the head of the pipe jacking machine. Using the three-dimensional coordinate control points, the readings of each ruler are measured. The pipe jacking angle, the deviation value of the pipe jacking center direction, the pipe jacking slope, the pipe jacking center elevation and other data are accurately calculated, so as to adjust the various construction parameters of the pipe jacking machine accordingly.

[0044] Ground settlement measurement: Ground settlement points are embedded in the road surface using road spikes. For structures with special requirements, red triangles are used for marking. Ground settlement observation is carried out daily during pipe jacking construction, and the settlement is controlled between +10 and -30 mm.

[0045] When a single section of pipe is pushed in halfway, in order to prevent the movement of the light point caused by the displacement of the backrest, laser instrument base or well wall, the axis center point and level point must be re-measured.

[0046] After the entire section is jacked up, measure the center position and elevation at each pipe joint. If there is misalignment, measure the height difference between the misalignments.

[0047] Correction should be carried out as measurements are taken, with correction occurring immediately after each measurement. The frequency of correction should be increased while the magnitude of correction should be reduced. Correction should be carried out frequently, in small amounts, and slowly. During the process of correcting deviations in the first section of the pipe, the measurement interval should not exceed 50cm to ensure that the pipe is correctly positioned in the soil. During the normal jacking stage after the pipe enters the soil layer, the measurement interval should not exceed 100cm.

[0048] Furthermore, in step S1, the grout used for the grouting material is made from phosphoric acid and water glass. The water glass is 40Be' (p = 1.38 g / cm3) and the phosphoric acid is 85% (weak acid, p = 1.7 q / cm3). Before grouting, the water glass is diluted with water at a ratio of 1:0.3 to form a water glass solution, and the phosphoric acid is diluted with water at a ratio of 1:10 to form a phosphoric acid solution. Then, the two solutions are used in a 1:1 ratio for soil reinforcement grouting.

[0049] Furthermore, in step S1, the grouting pressure is controlled by a "graded pressure increase method". When grouting begins, the pressure value should not be increased to the specified maximum value, but should be gradually increased from low to high. During grouting, an intermittent grouting method is adopted, and the interval time depends on the gelation time of the grout, which should be slightly shorter than the gelation time of the dry grout.

[0050] Furthermore, in step S1, if the grouting pressure suddenly increases, the injection of phosphate glass solution should be stopped and replaced with a certain amount of clean water. When the pump pressure returns to normal, the two-component grouting can be carried out again. If grout leakage occurs, cotton thread should be used to seal the leak and the grout concentration and mix ratio should be adjusted to shorten the gelation time. Small pump volume and low pressure grouting should be carried out to make the grout gel faster in the sand layer. Intermittent grouting can also be used, but the cessation time should not exceed the gelation time of the grout. If it is necessary to stop for a long time, the pipeline should be flushed with clean water to prevent the pipeline from being blocked.

[0051] If grouting is interrupted for any reason, it should be resumed as soon as possible. Otherwise, the borehole should be flushed immediately before grouting can be resumed. If flushing cannot solve the problem, the borehole should be cleaned before grouting can be resumed. When resuming grouting, the initial water-cement ratio should be used. When the injection rate is basically the same as before the interruption, the water-cement ratio before the interruption should be changed to the original ratio. If the injection rate is significantly lower than before the interruption, the grout should be gradually thickened for grouting. If the injection rate stops grouting within a short time after grouting is resumed, consider flushing the borehole or drilling additional boreholes on the side for reinforcement grouting.

[0052] Furthermore, in step S1, the following grouting standards must be met when grouting is completed:

[0053] ① The pressure at the grouting hole should be maintained at around 1.5 MPa, and the grout intake should not exceed 30 L / min for 5 minutes;

[0054] ② When the grout leakage point is 3-5m outside the grouting range;

[0055] ③ When the grouting volume in a single hole reaches 1.5-2.0 times the average grouting volume, and the grouting volume decreases significantly;

[0056] If the above standards are not met, the hole should be cleaned and grouting should be repeated.

[0057] Furthermore, in step S7, the high-calcium fly ash contains more than 10% calcium oxide in addition to silica and alumina. At the same time, the bulk density of fly ash is only about 2 / 3 of that of cement, and it has a good particle shape. Its "ball-like" effect can play a certain physical dispersing role on cement particles, making their distribution more uniform.

[0058] The ratio of replacement mud by weight is fly ash: cement: gypsum = 87.5:10:2.5. The replacement cement slurry containing a high amount of fly ash has a low hydration rate, and with the retarding effect of gypsum, the slump of the prepared replacement mud has a small loss over time, has good injectability, meets the replacement requirements, and has high strength and fast growth in the later stage, meeting the settlement control requirements.

[0059] Furthermore, in step S8, the pipe jacking error correction is carried out gradually. After an error is formed, the jacked pipe section should not be corrected immediately. Instead, it should be done slowly to allow the pipe section to gradually return to its original position. It should not be adjusted abruptly or forcefully to prevent the opposite result.

[0060] Furthermore, the method for constructing water leakage in pipe jacking projects is applied in the field of water leakage construction in pipe jacking projects.

[0061] This invention provides a method for constructing a water-bearing structure in a pipe jacking project, which has the following beneficial effects:

[0062] The construction method for preventing water leakage in this pipe jacking project involves the following steps: S1. Surface grouting; S2. Pumping; S3. Waterproofing and reinforcement of the tunnel entrance; S4. Measures to prevent pipe tilting at the tunnel entrance; S5. Internal pipe repair; S6. Back wall grouting; S7. Slurry replacement requirements; and S8. Measurement and correction. This approach helps to reduce and prevent water leakage in the pipeline, thus ensuring normal construction, preventing economic losses and personnel safety hazards caused by equipment flooding, and ensuring the normal progress of the project. Attached Figure Description

[0063] Figure 1 This is a schematic diagram of the surface grouting process for a water seepage construction method in pipe jacking engineering according to the present invention;

[0064] Figure 2 This is a schematic diagram of the grouting pipeline layout for a water seepage construction method in pipe jacking engineering according to the present invention;

[0065] Figure 3 This is a schematic diagram of the total station traverse control for a water seepage construction method in pipe jacking engineering according to the present invention;

[0066] Figure 4 This is a schematic diagram of laser theodolite measurement for a water seepage construction method in pipe jacking engineering according to the present invention. Detailed Implementation

[0067] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention.

[0068] like Figures 1-4 As shown, the present invention provides a technical solution: a method for constructing a water seepage prevention system in a pipe jacking project, the method comprising the following operational steps:

[0069] S1. Surface grouting:

[0070] Grouting process: Raw material inspection and on-site stacking — Layout of grouting holes — Drilling — Installation of grouting pipes (preparation of grouting materials and testing of grouting equipment) — Inspection of grouting pipes and grouting materials — Grouting. When determining the drilling position, the drilling position is 1.5m on each side of the jacking axis, arranged horizontally with a longitudinal interval of 1m. When drilling, apply light pressure and slow speed to ensure that the hole position does not deviate from the design angle and direction. After drilling is completed, the pipe wall and the hole opening are filled with hemp fiber. After the grouting pipe is installed and checked to be correct, grout is injected into the hole for consolidation. The grouting pipe plays a guiding role.

[0071] The grout used in the grouting material is made from phosphoric acid and water glass. The water glass is 40Be' (p = 1.38 g / cm3) and the phosphoric acid is 85% (weak acid, p = 1.7 q / cm3). Before grouting, the water glass is diluted with water at a ratio of 1:0.3 to form a water glass solution, and the phosphoric acid is diluted with water at a ratio of 1:10 to form a phosphoric acid solution. Then, the two solutions are used in a 1:1 ratio for soil reinforcement grouting.

[0072] During grouting, the "graded pressure increase method" is used to control the grouting pressure. When starting grouting, the pressure value should not be increased to the specified maximum value, but should be gradually increased from low to high. During grouting, an intermittent grouting method is used, and the interval time depends on the gelation time of the grout, which should be slightly shorter than the gelation time of the dry grout.

[0073] If the grouting pressure suddenly increases, stop injecting the phosphate glass solution and inject a certain amount of clean water instead. Once the pump pressure returns to normal, resume the two-component grouting. If grout leakage occurs, use cotton thread to seal the leak and adjust the grout concentration and mix ratio to shorten the gelation time. Use a small pump volume and low pressure to grout the grout so that it gels quickly in the sand layer. Intermittent grouting can also be used, but the cessation time should not exceed the gelation time of the grout. If a longer cessation is required, flush the pipeline with clean water to prevent blockage.

[0074] If grouting is interrupted for any reason, grouting should be resumed as soon as possible. Otherwise, the borehole should be flushed immediately before grouting can be resumed. If flushing cannot solve the problem, the borehole should be cleaned before grouting can be resumed. When resuming grouting, use the initial water-cement ratio. When the injection rate is basically the same as before the interruption, switch to the water-cement ratio before the interruption. If the injection rate is significantly reduced compared to before the interruption, the grout should be gradually thickened for grouting. After resuming grouting, if the injection rate stops grouting within a short period of time, consider flushing the borehole or drilling additional boreholes on the side for reinforcement grouting.

[0075] The following grouting standards must be met upon completion of grouting:

[0076] ① The pressure at the grouting hole should be maintained at around 1.5 MPa, and the grout intake should not exceed 30 L / min for 5 minutes;

[0077] ② When the grout leakage point is 3-5m outside the grouting range;

[0078] ③ When the grouting volume in a single hole reaches 1.5-2.0 times the average grouting volume, and the grouting volume decreases significantly;

[0079] If the above standards are not met, the hole should be cleaned and grouting should be repeated.

[0080] S2. Pumping method:

[0081] Pumping was scheduled to begin 6 hours after the completion of the phosphate-water glass double-liquid grouting. To ensure safety and facilitate monitoring of water level changes during pumping, the working well radius was 8 meters, and 200.96 cubic meters of water were pumped out for every 1 meter drop in water level. 3 Choose a 35KW water pump with a flow rate of 160m³ / hour. 3 ;

[0082] The pumping was carried out in three stages. The first stage involved pumping 3 meters of water and observing the water level continuously for 1 hour, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. The second stage involved pumping 3 meters of water and observing the water level continuously for 1 hour, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. The third stage involved pumping 4 meters of water and observing the water level continuously for 2 hours, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. At the same time, a designated person was assigned to observe the water volume in the "channel".

[0083] If the water level does not rise after the test pumping, timely maintenance of the pipe jacking machine should be arranged. If the water level rises significantly after the test pumping, underground cavities should be further explored and the grouting effect should be tested. If there are areas that are not dense, the grouting should be intensified at the tunnel entrance. The grouting range should be expanded to extend 9m to both sides along the central axis, with one hole every 1.5m and a longitudinal spacing of 1m. 4-6 rows of holes should be set, for a total of 36-48 holes. The grouting depth should be 50cm above the top of the pipe to the surface clay layer. Cement grout should be used to form a grouting curtain. The relevant parameters of the grouting process should refer to the method of drilled retaining pile + high-pressure jet grouting pile.

[0084] S3. Waterproofing and reinforcement of the tunnel entrance:

[0085] After grouting is completed and there is no water leakage, the tunnel portal reinforcement work is carried out. Before the portal reinforcement, the pipe is cut, the sealing of the curtain is checked, and the gap between the double-layer curtain is sealed. The construction process of using post-installed double-layer water-stop curtain for reinforcement is as follows:

[0086] Construction preparation → Measurement and positioning → Steel sleeve assembly and fixing → Curtain installation and fine-tuning → Curtain folding → Inspection and acceptance → Concrete pouring.

[0087] Construction preparation: Before construction, two semi-circular interlocking steel collars need to be customized in the factory. The inner diameter of the steel collar is 2580mm, the inner diameter of the curtain is 2000mm, and the outer diameter is 2850mm. The post-installed double-layer water-stop curtain pipe is used to ensure the welding quality. Considering the working surface width and the protection length of the curtain folding rubber during the welding process, the cutting position is determined to leave 10cm at the original sleeve opening, with a 60cm interval between the two sleeves. The bevel of the cut pipe is ground into a V-shape.

[0088] Measurement and positioning: The installation position of the steel sleeve is located according to the original center position of the tunnel entrance. Channel steel is used as a temporary external support to stabilize the steel sleeve. The channel steel of the external support is anchored to the original surrounding concrete with protective pads.

[0089] Steel sleeve assembly and fixing: The steel sleeve is hoisted to the measurement and positioning installation position in two stages using a 25t truck crane. The two sections of steel sleeve are connected with M24 bolts and welded firmly to the outer bracket. The assembly error is controlled within ±5mm. The elevation of the steel sleeve is measured and verified. If necessary, the position is finely adjusted by hand hoist. After the verticality is tested and qualified by plumb bob, a "radial" welded fixing frame support is finally formed.

[0090] Curtain installation and fine-tuning: Check the integrity of the rubber curtain, ensure that the bolt hole size deviation meets the installation requirements, and ensure that the φ24 bolt holes on the engineering ring plate are through holes evenly distributed at 9 degrees around the circumference. The bolt hole positions of the two ring plates must be consistent. When stacking two ring plates, ensure that all bolts can pass through the two ring plates at the same time. The curtain is sandwiched between the two ring plates, with the side with the round head facing the direction of travel. The high-strength bolts are temporarily inserted into the bolt holes symmetrically from bottom to top without being tightened. Check the exposed length of the curtain. If necessary, use a hand hoist to fine-tune the position of the curtain to ensure that the error is controlled within ±3mm. After inspection and approval, tighten the bolts symmetrically in sequence.

[0091] Curtain folding: The steel pipe cut is beveled and ground with a V-shaped bevel. After the internal weld of the pipe is completed, the pipe section is pushed in to fold the curtain. Before implementation, grease is applied to the surface of the curtain to prevent the bevel of the pipe section from cutting the curtain. After checking that the bevel is smooth and free of burrs, geotextile is used to temporarily wrap the bevel of the pipe section. Then, the pipe section is slowly pushed in the direction of the curtain at the tunnel entrance. During the pushing, a special person is arranged to check the folding of the curtain. If twisting or other abnormalities occur, the pushing should be stopped immediately and a blunt instrument is used to assist in the folding.

[0092] Concrete pouring: After passing the inspection, install the formwork and pour concrete to encase the water-stopping device and fixing frame of the tunnel entrance, forming a permanent water-stopping tunnel entrance structure. This construction method uses C30 concrete with good workability and a permeability grade of P6. The concrete slump is controlled at 180-220mm. Before pouring, the contact surfaces between the newly poured concrete and the original well wall and bottom slab should be roughened. Concrete should be poured in layers symmetrically, with each layer having a pouring height of 300mm. Considering that it is difficult to vibrate in places, a small hand-held cement vibrator is used for vibration, especially at the junction of the steel components and the tunnel entrance, where manual vibration is used to ensure the structure is dense.

[0093] S4. Measures to prevent pipes from tilting upwards at the opening section:

[0094] To prevent the pipeline tail from tilting upwards due to increased buoyancy after the reservoir and the jacking pipe connect to the ground during the jacking process, a limiting stiffening rib is added between the double-layer curtain fabric. The preferred material is a 45mm thick hard rubber strip, half the outer circumference of the pipe, and 50mm wide. To avoid direct contact between the fixing bolts and the pipeline, tapered bolt holes are used. After the rubber strip is firmly fixed with M16 bolts, the stiffening rib is welded firmly to the steel collar between the two layers of curtain fabric.

[0095] S5. In-pipe maintenance:

[0096] After the water in the pipeline is pumped out, the electrical equipment inside the pipe jacking machine is inspected and repaired. Due to the weight of the electrical equipment, a partition plate is set up during dismantling. The equipment is manually lifted out of the chamber door and transported to the outside of the pipe and then to the outside of the well for repair by handcart. The installation is carried out in the same way.

[0097] S6. Backwall grouting:

[0098] To stabilize the strata, a low-ratio cement-water glass double-liquid grout was injected behind the wall at a position 18m from the tunnel entrance. The specific ratio was determined through experiments based on requirements. Each two pipe sections were grouped together, with injection and discharge holes. The grouting pump was cleaned, and the suction pipe with a valve was placed into the grout pool. The grouting pump was turned on, and the first group of injection holes was opened for grouting. When grout emerged from the first group of discharge holes, the valves were closed, and the second group was opened. This process was repeated until the entire line was completed. Then, all valves were closed, and the pressure was maintained for 20 minutes at 1MPa. Considering the potential structural damage caused by pipe movement during the jacking process, grouting was performed once after each pipe section was jacked.

[0099] S7. Requirements for mud replacement:

[0100] Slurry replacement refers to the immediate replacement of the original bentonite slurry injected into the outer wall of the pipe with hydraulic materials after the completion of a single section of pipe jacking. This creates a high-strength slurry wall on the outer wall of the pipe, capable of withstanding the pressure of the overlying soil and preventing the collapse of the borehole wall. In addition, the addition of an expanding agent to the cement slurry, which has shrinkage-compensating properties, can further reduce the shrinkage of the original slurry, thereby reducing settlement. The replacement slurry for pipe jacking construction is a high-volume fly ash cement slurry made from high-calcium fly ash, cement, and gypsum.

[0101] Replacement principle: Each two pipe sections are grouped together, consisting of grouting holes and grout discharge holes. The grouting pump is cleaned, and the suction pipe with valve is placed into the grout pool. The grouting pump is turned on, and the first group of grouting holes is opened for grouting. When grout emerges from the first group of grout discharge holes, the valve is closed, and the second group is opened. This process is repeated until the entire line is completed. Then, all valves are closed, and the pressure is maintained for 30 minutes at a pressure of 1 MPa.

[0102] After the mud replacement is completed, the main channel grout pipe and the arc-shaped grout pipe inside the pipe section are removed and cleaned on site to prevent the grout from solidifying and clogging, which would affect the later use. After the mud replacement is completed, the grouting hole is sealed: the replacement cement grout on the outside of the grouting hole pipe wall is removed, and the removal range is 5cm around the grouting hole and 1.5cm vertical depth on the pipe wall.

[0103] In step S7, high-calcium fly ash contains more than 10% calcium oxide in addition to silica and alumina. At the same time, the bulk density of fly ash is only about 2 / 3 of that of cement, and it has a good particle shape. Its "ball-like" effect can play a certain physical dispersion role on cement particles, making them more evenly distributed.

[0104] The ratio of replacement mud by weight is fly ash: cement: gypsum = 87.5:10:2.5. The replacement cement mud containing a high amount of fly ash has a low hydration rate, and under the retarding effect of gypsum, the slump of the prepared replacement mud has a small loss over time, with good injectability, which meets the replacement requirements. At the same time, it has high strength and fast growth in the later stage, which meets the settlement control requirements.

[0105] S8. Measurement and Correction:

[0106] During the pipe jacking construction phase, measurement is crucial. Frequent measurements and timely corrections are essential. It is unacceptable to reduce or omit measurements simply to speed up the process. Generally, measurements should be taken before the pipe is lowered and after the jacking process begins. This allows for easier correction of any deviations detected at these times. During normal jacking, measurements should be taken every 30cm of jacking and again after the entire jacking has progressed 1m. Measurements are performed using a laser theodolite, with a fixed laser target mounted on the jacking head. The jacking direction of the pipe jacking machine is adjusted promptly based on the data fed back from the laser theodolite and the laser target during the jacking process.

[0107] Planar control: total station, laser theodolite;

[0108] ① To ensure the pipe jacking between the two wells is connected and the lateral and vertical errors are less than 100mm, ground traverse points are buried near the two end wells. Using the empty traverse points and the ground traverse points, the plane control results are transferred to the construction site in the form of traverse surveying.

[0109] A plane control network was established using air traverse points and ground traverse points. The traverse survey was conducted using a total station. Six rounds of direction observations were performed with an angle measurement accuracy of +1. Six rounds of distance measurement were performed with bidirectional observations. The relative error of the distance measurement was <1 / 120000. The observation results were then adjusted.

[0110] ② The transfer of surface coordinates to the underground uses a connecting triangle method, with the points being vertically projected by a laser theodolite;

[0111] Elevation measurement: Laser theodolite;

[0112] ①Using known high-level benchmarks near the construction area, a fourth-order leveling route was set up to transfer the elevation to the vicinity of the working well, and construction elevation control points were established;

[0113] ② When transferring the ground elevation to the well, a steel tape can be suspended vertically with a plumb bob attached to the standard tension. Then, two levels, one on the ground and one in the well, can be used to observe simultaneously. The steel tape should be corrected for both tape length and temperature. Two to three underground starting elevation control points should be set up in the well.

[0114] ③ The elevation control level of the pipe jacking machine head is used to measure the deviation value every 20cm of jacking to keep track of the machine head's posture and development trend in a timely manner so as to correct the deviation in time;

[0115] Jacking posture measurement: In order to ensure that the pipe jacking machine advances strictly according to the design axis, it is necessary to observe the dynamic data of pipe jacking in a timely manner, so as to adjust the various construction parameters of pipe jacking and guide the correct and safe advancement of pipe jacking;

[0116] A pair of horizontal rulers are set longitudinally at the head of the pipe jacking machine. Using the three-dimensional coordinate control points, the readings of each ruler are measured. The pipe jacking angle, the deviation value of the pipe jacking center direction, the pipe jacking slope, the pipe jacking center elevation and other data are accurately calculated, so as to adjust the various construction parameters of the pipe jacking machine accordingly.

[0117] Ground settlement measurement: Ground settlement points are embedded in the road surface using road spikes. For structures with special requirements, red triangles are used for marking. Ground settlement observation is carried out daily during pipe jacking construction, and the settlement is controlled between +10 and -30 mm.

[0118] When a single section of pipe is pushed in halfway, in order to prevent the movement of the light point caused by the displacement of the backrest, laser instrument base or well wall, the axis center point and level point must be re-measured.

[0119] After the entire section is jacked up, measure the center position and elevation at each pipe joint. If there is misalignment, measure the height difference between the misalignments.

[0120] Correction should be carried out as measurements are taken, and correction should be carried out as measurements are taken. The frequency of correction should be increased and the amplitude of correction should be reduced. The principle of correction should be frequent, infrequent and slow. During the process of correcting the deviation of the first section of pipe, the measurement interval should not exceed 50cm to ensure that the pipe is correctly positioned in the soil. During the normal jacking stage after the pipe enters the soil layer, the measurement interval should not exceed 100cm.

[0121] Among them, the correction of pipe jacking error is carried out gradually. After an error is formed, the jacked pipe section should not be corrected into place immediately. It should be done slowly so that the pipe section can be gradually reset. It should not be drastically adjusted to prevent the opposite result.

[0122] The term "water leakage construction method" is applied to the field of water leakage construction in pipe jacking projects.

[0123] The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the invention to the forms disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles and practical application of the invention, and to enable those skilled in the art to understand the invention and to design various embodiments with various modifications suitable for a particular purpose.

Claims

1. A pipe jacking engineering water emerging construction method, characterized in that: The water seepage construction method for pipe jacking projects includes the following operational steps: S1. Surface grouting: Grouting process: Raw material inspection and on-site stacking — Layout of grouting holes — Drilling — Installation of grouting pipes, preparation of grouting materials, testing of grouting equipment — Inspection of grouting pipes and grouting materials — Grouting. When determining the drilling position, the drilling position is 1.5m on each side of the jacking axis, arranged horizontally with a longitudinal interval of 1m. When drilling, apply light pressure and slow speed to ensure that the hole position does not deviate from the design angle and direction. After drilling is completed, the pipe wall and the hole opening are filled with hemp fiber. After the grouting pipe is installed and checked to be correct, grout is injected into the hole for consolidation. The grouting pipe plays a guiding role. S2. Pumping method: The pumping time is selected to be 6 hours after all the phosphate water glass double liquid grouting is completed. In order to ensure the safety of pumping and to ensure that the water level changes are observed as much as possible during pumping, the working well radius is 8m, and 200.96m³ of water is pumped for every 1m drop. A 35KW pump is selected with a flow rate of 160m³ per hour. The pumping was carried out in three stages. The first stage involved pumping 3 meters of water and observing the water level continuously for 1 hour, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. The second stage involved pumping 3 meters of water and observing the water level continuously for 1 hour, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. The third stage involved pumping 4 meters of water and observing the water level continuously for 2 hours, with the water level changing every 10 minutes. This process was repeated 6 times and the results were recorded. At the same time, a designated person was assigned to observe the water volume in the "channel". If the water level does not rise after the test pumping, timely maintenance of the pipe jacking machine should be arranged. If the water level rises significantly after the test pumping, underground cavities should be further explored and the grouting effect should be tested. If there are areas that are not dense, the grouting should be intensified at the tunnel entrance. The grouting range should be expanded to extend 9m to both sides along the central axis, with one hole every 1.5m and a longitudinal spacing of 1m. 4-6 rows of holes should be set, for a total of 36-48 holes. The grouting depth should be 50cm above the top of the pipe to the surface clay layer. Cement grout should be used to form a grouting curtain. The relevant parameters of the grouting process should refer to the method of drilled retaining pile + high-pressure jet grouting pile. S3. Reinforcement of the portal water-stopping system: After grouting is completed and there is no water leakage, the tunnel portal reinforcement work is carried out. Before the portal reinforcement, the pipe is cut, the sealing of the curtain is checked, and the gap between the double-layer curtain is sealed. The construction process of using post-installed double-layer water-stop curtain for reinforcement is as follows: Construction preparation → Measurement and positioning → Steel sleeve assembly and fixing → Curtain installation and fine-tuning → Curtain folding → Inspection and acceptance → Concrete pouring. Construction preparation: Before construction, two semi-circular interlocking steel collars need to be customized in the factory. The inner diameter of the steel collar is 2580mm, the inner diameter of the curtain is 2000mm, and the outer diameter is 2850mm. The post-installed double-layer water-stop curtain pipe is used to ensure the welding quality. Considering the working surface width and the protection length of the curtain folding rubber during the welding process, the cutting position is determined to be 10cm reserved at the original sleeve opening, with a 60cm interval between the two sleeves. The bevel of the cut pipe is ground into a V-shape. Measurement and positioning: The installation position of the steel sleeve is located according to the original center position of the tunnel entrance. Channel steel is used as a temporary external support to stabilize the steel sleeve. The channel steel of the external support is anchored to the original surrounding concrete with protective pads. Steel sleeve assembly and fixing: The steel sleeve is hoisted to the measurement and positioning installation position in two stages using a 25t truck crane. The two sections of steel sleeve are connected with M24 bolts and welded firmly to the outer bracket. The assembly error is controlled within ±5mm. The elevation of the steel sleeve is measured and verified. The position is finely adjusted by hand chain hoist. After the verticality is tested and qualified by plumb bob, a "radial" welded fixing frame support is finally formed. Curtain installation and fine-tuning: Check the integrity of the rubber curtain, ensure that the bolt hole size deviation meets the installation requirements, and ensure that the φ24 bolt holes on the engineering ring plate are through holes evenly distributed at 9 degrees around the circumference. The bolt hole positions of the two ring plates must be consistent. When stacking two ring plates, ensure that all bolts can pass through the two ring plates at the same time. The curtain is sandwiched between the two ring plates, with the round head side facing the forward direction. The high-strength bolts are temporarily inserted into the bolt holes symmetrically from bottom to top without being tightened. Check the exposed length of the curtain and use a hand hoist to fine-tune the position of the curtain to ensure that the error is controlled within ±3mm. After inspection and approval, tighten the bolts symmetrically in sequence. Curtain folding: The steel pipe cut is beveled and ground with a V-shaped bevel. After the internal weld of the pipe is completed, the pipe section is pushed in to fold the curtain. Before implementation, grease is applied to the surface of the curtain to prevent the bevel of the pipe section from cutting the curtain. After checking that the bevel is smooth and free of burrs, geotextile is used to temporarily wrap the bevel of the pipe section. Then, the pipe section is slowly pushed in the direction of the curtain at the tunnel entrance. During the pushing, a special person is assigned to check the folding of the curtain. If any abnormal twisting occurs, the pushing should be stopped immediately and a blunt instrument should be used to assist in the folding. Concrete pouring: After passing the inspection, install the formwork and pour concrete to encase the water-stopping device and fixing frame of the tunnel entrance with concrete to form a permanent water-stopping tunnel entrance structure. This construction method uses C30 concrete with good workability and a permeability grade of P6. The concrete slump is controlled at 180-220mm. Before pouring, the contact surface between the newly poured concrete and the original well wall and bottom slab should be roughened. When pouring concrete, it should be done in layers symmetrically, with each layer poured to a height of 300mm. Considering that it is difficult to vibrate in place in some areas, a small hand-held cement vibrator is used for vibration. The joint between the steel components and the tunnel entrance is supplemented with manual vibration to ensure the structure is dense. S4. Measures to prevent pipes from tilting upwards at the opening section: To prevent the pipeline tail from tilting upwards due to increased buoyancy after the reservoir and the jacking pipe connect to the ground during the jacking process, a limiting stiffening rib is added between the double-layer curtain fabric. The rib is half the outer circumference of the pipe and 50mm wide. To avoid direct contact between the fixing bolts and the pipeline, a tapered bolt hole is used. At the same time, the rubber strip is firmly fixed with M16 bolts, and the stiffening rib is welded firmly to the steel collar between the two layers of curtain fabric. S5. In-pipe maintenance: After the water in the pipeline is pumped out, the electrical equipment inside the pipe jacking machine is inspected and repaired. Due to the weight of the electrical equipment, a partition plate is set up during dismantling. The equipment is manually lifted out of the chamber door and transported to the outside of the pipe and then to the outside of the well for repair by handcart. The installation is carried out in the same way. S6. Backwall grouting: To stabilize the strata, a low-ratio cement-water glass double-liquid grout was injected behind the wall at a position 18m from the tunnel entrance. The specific ratio was determined through experiments based on requirements. Two pipe sections were grouped together, with injection and discharge holes set up separately. The grouting pump was cleaned, and the suction pipe with a valve was placed into the grout pool. The grouting pump was turned on, and the first set of injection holes was opened for grouting. When grout emerged from the first set of discharge holes, the valve was closed, and the second set was opened. This process was repeated until the entire line was completed. Then, all valves were closed, and the pressure was maintained for 20 minutes at a pressure of 1MPa. During the jacking process, considering the possibility of pipe movement causing structural damage, grouting was performed once after each pipe section was jacked. S7. Requirements for mud replacement: Slurry replacement refers to the immediate replacement of the original bentonite slurry injected into the outer wall of the pipe with hydraulic materials after the completion of a single section of pipe jacking. This creates a high-strength slurry wall on the outer wall of the pipe, capable of withstanding the pressure of the overlying soil and preventing the collapse of the borehole wall. In addition, the addition of an expanding agent to the cement slurry, which has shrinkage-compensating properties, can further reduce the shrinkage of the original slurry, thereby reducing settlement. The replacement slurry for pipe jacking construction is a high-volume fly ash cement slurry made from high-calcium fly ash, cement, and gypsum. Replacement principle: Each pair of pipe sections is braided into a group, with grouting holes and grout discharge holes respectively. The grouting pump is cleaned, and the suction pipe with valve is placed into the grout pool. The grouting pump is turned on, and the first group of grouting holes is opened for grouting. When grout emerges from the first group of grout discharge holes, the valve is closed, and the second group is opened. This process is repeated until the entire line is completed. Then all valves are closed, and the pressure is maintained for 30 minutes at a pressure of 1 MPa. After the mud replacement is completed, the main channel grout pipe and the arc-shaped grout pipe inside the pipe section are removed and cleaned on site to prevent the grout from solidifying and clogging, which would affect the later use. After the mud replacement is completed, the grouting hole is sealed: the replacement cement grout on the outside of the grouting hole pipe wall is removed, and the removal range is 5cm around the grouting hole and 1.5cm vertical depth on the pipe wall. S8. Measurement and Correction: During the pipe jacking construction phase, measurement is crucial. Frequent measurements and timely corrections are essential. It is unacceptable to reduce or omit measurements simply to speed up the process. Measurements should be taken before and after the pipe is lowered and the jacking process begins. This allows for easier correction of any deviations detected at these times. During normal jacking, measurements should be taken every 30cm of jacking and again after the entire jacking has progressed 1m. Measurements should be conducted using a laser theodolite with a fixed laser target mounted on the jacking head. The jacking direction should be adjusted promptly based on the data from the laser theodolite and the laser target during the jacking process. Planar control: total station, laser theodolite; ① To ensure the pipe jacking between the two wells is connected and the lateral and vertical errors are less than 100mm, ground traverse points are buried near the two end wells. Using the empty traverse points and the ground traverse points, the plane control results are transferred to the construction site in the form of traverse surveying. A plane control network was established using air traverse points and ground traverse points. The traverse survey was conducted using a total station. Six rounds of direction observations were performed with an angle measurement accuracy of +1. Six rounds of distance measurement were performed with bidirectional observations. The relative error of the distance measurement was <1 / 120000. The observation results were then adjusted. ② The transfer of surface coordinates to the underground uses a connecting triangle method, with the points being vertically projected by a laser theodolite; Elevation measurement: Laser theodolite; ①Using known high-level benchmarks near the construction area, a fourth-order leveling route was set up to transfer the elevation to the vicinity of the working well, and construction elevation control points were established; ② When transferring the ground elevation to the well, a steel tape can be suspended vertically with a plumb bob attached to the standard tension. Then, two levels, one on the ground and one in the well, can be used to observe simultaneously. The steel tape should be corrected for both tape length and temperature. Two to three underground starting elevation control points should be set up in the well. ③ The elevation control level of the pipe jacking machine head is used to measure the deviation value every 20cm of jacking to keep track of the machine head's posture and development trend in a timely manner so as to correct the deviation in time; Jacking posture measurement: In order to ensure that the pipe jacking machine advances strictly according to the design axis, it is necessary to observe the dynamic data of pipe jacking in a timely manner, so as to adjust the various construction parameters of pipe jacking and guide the correct and safe advancement of pipe jacking; A pair of horizontal rulers are set longitudinally at the head of the pipe jacking machine. Using the three-dimensional coordinate control points, the readings of each ruler are measured. The four types of data are accurately calculated: pipe jacking angle, pipe jacking center direction deviation, pipe jacking slope, and pipe jacking center elevation. The various construction parameters of the pipe jacking machine are then adjusted accordingly. Ground settlement measurement: Ground settlement points are embedded in the road surface using road spikes. Ground settlement observation is carried out daily during pipe jacking construction, and the settlement is controlled between +10 and -30 mm. When a single section of pipe is pushed in halfway, in order to prevent the movement of the light point caused by the displacement of the backrest, laser instrument base or well wall, the axis center point and level point must be re-measured. After the entire section is jacked up, measure the center position and elevation at each pipe joint. If there is misalignment, measure the height difference between the misalignments. Correction should be carried out as measurements are taken, with correction occurring immediately after each measurement. The frequency of correction should be increased while the magnitude of correction should be reduced. Correction should be carried out frequently, in small amounts, and slowly. During the process of correcting deviations in the first section of the pipe, the measurement interval should not exceed 50cm to ensure that the pipe is correctly positioned in the soil. During the normal jacking stage after the pipe enters the soil layer, the measurement interval should not exceed 100cm.

2. The method for constructing a water-bearing structure in a pipe jacking project according to claim 1, characterized in that: In step S1, the grout used for the grouting material is made from phosphoric acid and water glass, with water glass of 40Be' and 85% phosphoric acid. Before grouting, the water glass is diluted with water at a ratio of 1:0.3 to form a water glass solution, and the phosphoric acid is diluted with water at a ratio of 1:10 to form a phosphoric acid solution. Then, the two solutions are used in a 1:1 ratio for soil reinforcement grouting.

3. The method for constructing a water-bearing structure in a pipe jacking project according to claim 1, characterized in that: In step S1, the grouting pressure is controlled by the "graded pressure increase method". When grouting begins, the pressure value should not be increased to the specified maximum value. Instead, it should be gradually increased from low to high. During grouting, an intermittent grouting method is adopted. The interval time depends on the gelation time of the grout and should be slightly shorter than the gelation time of the dry grout.

4. The method for constructing a water-bearing structure in a pipe jacking project according to claim 1, characterized in that: In step S1, if the grouting pressure suddenly increases, the injection of phosphate glass solution should be stopped and replaced with a certain amount of clean water. When the pump pressure returns to normal, the two-component grouting can be resumed. If grout leakage occurs, cotton thread should be used to seal the leak and the grout concentration and mix ratio should be adjusted to shorten the gelation time. Grouting should be carried out with a small pump volume and low pressure to allow the grout to gel faster in the sand layer. Intermittent grouting can also be used, but the cessation time should not exceed the gelation time of the grout. If a longer cessation is required, the pipeline should be flushed with clean water to prevent blockage. If grouting is interrupted for any reason, it should be resumed as soon as possible. Otherwise, the borehole should be flushed immediately before grouting can be resumed. If flushing cannot solve the problem, the borehole should be cleaned before grouting can be resumed. When resuming grouting, the initial water-cement ratio should be used. When the injection rate is basically the same as before the interruption, the water-cement ratio before the interruption should be changed to the original ratio. If the injection rate is significantly lower than before the interruption, the grout should be gradually thickened for grouting. If the injection rate stops grouting within a short time after grouting is resumed, consider flushing the borehole or drilling additional boreholes on the side for reinforcement grouting.

5. The method for constructing a water-bearing structure in a pipe jacking project according to claim 1, characterized in that: In step S1, the following grouting standards must be met when grouting is completed: ① The pressure at the grouting hole should be maintained at around 1.5 MPa, and the grout intake should not exceed 30 L / min for 5 minutes; ② When the grout leakage point is 3-5m outside the grouting range; ③ When the grouting volume in a single hole reaches 1.5-2.0 times the average grouting volume, and the grouting volume decreases significantly; If the above standards are not met, the hole should be cleaned and grouting should be repeated.

6. The method for constructing a water-bearing structure in a pipe jacking project according to claim 1, characterized in that: In step S7, the high-calcium fly ash contains more than 10% calcium oxide in addition to silica and alumina. At the same time, the bulk density of fly ash is only about 2 / 3 of that of cement, and it has a good particle shape. Its "ball-like" effect can play a certain role in the physical dispersion of cement particles, making their distribution more uniform. The ratio of the replacement mud by weight is fly ash: cement: gypsum = 87.5: 10: 2.

5. The replacement cement mud containing a high amount of fly ash has a low hydration rate, and with the retarding effect of gypsum, the slump of the prepared replacement mud has a small loss over time, has good injectability, meets the replacement requirements, and has high strength and fast growth in the later stage, meeting the settlement control requirements.

7. The method for constructing a water-bearing structure in a pipe jacking project according to claim 1, characterized in that: In step S8, the correction of pipe jacking error is carried out gradually. After an error is formed, the jacked pipe section should not be corrected immediately. Instead, it should be done slowly to allow the pipe section to gradually return to its original position. It should not be adjusted abruptly to prevent the opposite result.

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