Construction method of shield cutting pile foundation

Abstract

The invention belongs to the technical field of shield cutting pile foundations, and discloses a construction method of a shield cutting pile foundation, which comprises the following steps: S1, selecting a cutterhead and configuring a cutter; s3, the shield tunneling machine is started for tunneling so as to drive a duplex hob, a double-edged hob and a tearing cutter to cut the pile foundation and the soil body, and a front scraper and an edge scraper scrape the cut pile foundation and the cut soil body; s4, reinforcing steel bar sections and large residue soil generated in the cutting process are filtered through a filtering grating in the quarrying box, and the reinforcing steel bar sections and the large residue soil are prevented from entering a residue discharging opening of the air cushion bin through two or more open type gratings; and S5, regularly starting the screw conveyor to discharge the steel bar sections filtered in the quarrying box and the large muck out of the quarrying box. By selecting and configuring the composite cutterhead cutter, reinforced concrete can be effectively crushed, tunneling of a shield can be guaranteed, and the problems that the cutterhead cutter is low in tunneling efficiency in a soft soil layer and the cutter is prone to eccentric wear are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of shield cutting pile foundation, and in particular relates to a construction method of shield cutting pile foundation. Background Art

[0002] In recent years, my country's urban rail transit has developed rapidly. In the process of urban tunnel construction, shield machines are usually used for tunnel excavation. Due to the influence of relevant factors such as the urban environment and the subway lines under construction, the planning of the shield line will inevitably conflict with the original buildings and structures, which is easy to cause damage to the existing buildings and structures, and cause major safety accidents such as collapse and settlement. When encountering pile foundations in composite strata, the generally used disposal technology is mainly to dismantle the original bridge pile foundation in advance or change the tunnel line, and then carry out shield excavation construction, but this construction method increases the difficulty of construction and the construction period is long. Therefore, there is currently a method of using a shield machine to directly remove the reinforced concrete pile foundation during the excavation process.

[0003] Existing shield machines usually use toothed cutters as cutting tools on the front and periphery of the shield. Such cutters can reduce cutter wear in soft soil, but have no advantage in cutting reinforced concrete piles, which makes the cutter prone to eccentric wear and makes it impossible to ensure the excavation of the shield. At the same time, the cut steel bars and large slag are easy to get stuck in the pump impeller and block the pipeline, which poses a great risk in construction. Therefore, we propose a construction method for shield cutting pile foundation to solve the above problems. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a construction method for shield cutting pile foundation, which solves the problems of severe eccentric wear of shield cutters and the easy jamming of pump impellers and clogging of pipelines by cut steel bars and large slag.

[0005] The present invention is implemented by the following scheme: A construction method for shield cutting pile foundation, comprising:

[0006] S1. Selection of cutter disc and configuration of cutter:

[0007] S11, use spoke-type cutter disc;

[0008] S12, a double roller is installed at the center of the cutter disc, a double-edged roller is installed on each spoke on the front of the cutter disc, a row of front scrapers are installed on both sides of each spoke, and a circle of edge scrapers and a circle of tearing knives are installed in sequence from the inside to the outside on the periphery of the cutter disc;

[0009] S2. Add quarrying boxes and open grilles:

[0010] S21. A quarrying box is installed in front of the inlet of the slurry pump of the shield machine trailer, and a filter grid is arranged inside the quarrying box;

[0011] S22, a screw conveyor is arranged at the slurry discharge port of the quarrying box;

[0012] S23, installing two or more open grilles at the mud door positions at the bottom of the mud and water bin and the air cushion bin, and the two or more open grilles are arranged at intervals;

[0013] S3, start the shield machine, control the shield machine to dig along the designed route in the soft soil layer, drive the double roller cutter, double-edged roller cutter and tearing cutter to cut the pile foundation and soil, and the front scraper and side scraper to scrape the cut pile foundation and soil;

[0014] S4. During the tunneling process of the shield machine, the steel bars and large slag generated during the cutting process are filtered out by the filter grid inside the quarrying box, and two or more open grids are used to prevent the steel bars and large slag from entering the slag discharge port of the air cushion bin;

[0015] S5. Start the screw machine regularly to discharge the steel bars and large debris filtered out of the quarrying box.

[0016] The construction method of the shield cutting pile foundation of the present invention is further improved in that, before controlling the shield machine to excavate along the designed route in the soft soil layer, it also includes the steps of: setting the construction parameters of the shield machine;

[0017] The construction parameters of the shield machine include: soil bin pressure of 2.0-2.2 bar, shield advancement speed of 2-3 mm / min, cutter head speed of 0.5-0.8 rpm, cutter head average torque ≤2000 KNm, torque fluctuation ≤300 KNm, maximum thrust ≤2500 T, soil bin pressure fluctuation less than ±0.1 bar, shield tail grease filling amount of 80-100 kg per ring, excavation soil loss ≤5‰, excavation volume ≤39.03 m 3 And the amount of cutter disc sealing grease added to each ring should be no less than 4kg.

[0018] A further improvement of the construction method of the shield cutting pile foundation of the present invention is that the construction parameters of the shield machine also include setting the excavated soil layer to an under-excavation mode, setting it to an under-pressure excavation mode during the excavation process, and setting the uplift value of the soil above the shield incision to no more than 0.5 mm.

[0019] A further improvement of the construction method of shield cutting pile foundation of the present invention is that the step S3 further comprises the steps of: synchronous grouting when cutting the pile foundation and the soil;

[0020] After the pile is passed, secondary grouting is carried out and surface monitoring is carried out at any time;

[0021] When the surface settlement is monitored to be within ±2mm / maintained within the range of ±2mm, stop the secondary grouting and continue excavation until the cutting is completed.

[0022] A further improvement of the construction method of the shield cutting pile foundation of the present invention is that the secondary grouting adopts double slurry, and the double slurry is composed of cement, water glass and water in a weight ratio of 1:0.06:0.8.

[0023] A further improvement of the shield cutting pile foundation construction method of the present invention is that, during the shield machine excavation process, it also includes the step of: injecting a composite bentonite slurry with a certain viscosity into the soil bin to ensure that the soil bin pressure fluctuation is within the range of ±0.1 bar.

[0024] A further improvement of the construction method of shield cutting pile foundation of the present invention is that the construction method further comprises: after the shield tail of the shield machine escapes from the pile foundation area, reinforcing grouting is performed through the grouting holes reserved on the pipe segment.

[0025] A further improvement of the shield cutting pile foundation construction method of the present invention is that the shield machine is controlled to excavate along the designed route in the soft soil layer in accordance with the railway mainline settlement control standard.

[0026] A further improvement of the construction method of the shield cutting pile foundation of the present invention is that the railway mainline settlement control standard is: the railway line uplift per hour is ≤2mm, and the hourly settlement is ≤4mm; the cumulative uplift per day and night is ≤4mm, and the cumulative settlement per day and night is ≤10mm; the horizontal height difference between the two rail tops is ≤2mm, and the cumulative uplift of the final line within half a year is ≤10mm, and the cumulative settlement is ≤40mm.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The present invention can effectively crush reinforced concrete and ensure the excavation of the shield by selecting and configuring composite cutter disc tools, and solves the problems of low excavation efficiency of cutter disc tools in soft soil layers and easy eccentric wear of cutters. In the entire shield cutting pile foundation process, full-disc disc type roller cutters are mainly used. At the same time, tearing knives are welded on the outer ring of the cutter disc of the shield machine, which can enhance the cutting strength of the outer ring tool, enhance the ability of the shield machine to directly cut piles and remove obstacles, avoid the risk of cutter disc jamming caused by direct shield cutting of pile foundations, and effectively crush the pile foundation through the roller cutter, so that subsequent soft soil excavation is guaranteed.

[0029] 2. The present invention can enhance the filtering of steel bars by adding a quarrying box and an open grille, reduce the risk of slurry discharge pipeline being blocked, reduce the risk of the cutter disc being stuck and the spiral machine being pressed into the bin to clean the steel bars, and reduce construction risks. The quarrying box is used to filter the large pieces of debris and steel bar foreign matter generated during the shield pile cutting process. During the shield pile cutting process, the spiral machine is used to regularly send the debris and steel bars deposited inside the quarrying box out of the quarrying box to avoid the phenomenon of pump impeller being stuck and pipeline being blocked. The open grille is used to prevent steel bars and large pieces of debris from directly entering the slag discharge port of the air cushion bin and causing blockage.

[0030] 3. Set construction parameters before cutting to ensure the advancement of the shield machine. During the shield cutting and excavation process, under-pressure excavation can be adopted to form a soil plug at the excavation port, which plays a good role in sealing, pressure maintenance and blowout prevention, and ensures construction safety. At the same time, it avoids the risk of uncontrollable excavation when the shield directly cuts the pile foundation, shortens the overall construction period, and reduces construction costs. By adopting the under-excavation method and ensuring that the soil above the shield incision has a bulge of ≤0.5mm, it can effectively offset the later settlement of part of the soil, avoid ground collapse, and ensure the successful implementation of the cutting construction. Reinforcement grouting can strengthen the support of the pipe segment to the stratum and ensure the safety of the tunnel in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A flow chart of the construction method of the shield cutting pile foundation of the present invention is shown. DETAILED DESCRIPTION

[0032] In order to solve the problem of serious eccentric wear of shield cutters and the problem that the cut steel bars and large slag easily get stuck in the pump impeller and block the pipeline, the present invention provides a construction method for shield cutting pile foundation. The following is a further description of the construction method for shield cutting pile foundation with specific embodiments and accompanying drawings.

[0033] See also Figure 1 As shown, a construction method of shield cutting pile foundation includes:

[0034] S1. Selection of cutter disc and configuration of cutter:

[0035] S11, use spoke-type cutter disc;

[0036] S12, install 6 double rollers in the center of the cutter disc, install 16 double-edged rollers on each spoke on the front of the cutter disc, install a row of (44) front scrapers on both sides of each spoke, and install a circle of (8) side scrapers and a circle of (6) tearing knives from the inside to the outside on the periphery of the cutter disc;

[0037] S2. Add quarrying boxes and open grilles:

[0038] S21. A quarrying box is installed in front of the inlet of the slurry pump of the shield machine trailer, and a filter grid is arranged inside the quarrying box;

[0039] S22, a screw conveyor is arranged at the slurry discharge port of the quarrying box;

[0040] S23, installing two or more open grilles at the mud door positions at the bottom of the mud and water bin and the air cushion bin, and the two or more open grilles are arranged at intervals;

[0041] S3, start the shield machine, control the shield machine to dig along the designed route in the soft soil layer, drive the double roller cutter, double-edged roller cutter and tearing cutter to cut the pile foundation and soil, and the front scraper and side scraper to scrape the cut pile foundation and soil;

[0042] S4. During the tunneling process of the shield machine, the steel bars and large slag generated during the cutting process are filtered out by the filter grid inside the quarrying box, and two or more open grids are used to prevent the steel bars and large slag from entering the slag discharge port of the air cushion bin;

[0043] S5. Start the screw machine regularly to discharge the steel bars and large debris filtered out of the quarrying box.

[0044] Specifically, the cutterhead opening rate is 40%; before starting the shield machine excavation, it also includes: positioning the pile foundation in the soft soil layer; equipment maintenance and material storage: checking the supporting construction equipment to ensure that the performance is intact and whether the materials required during the shield excavation can be supplied normally;

[0045] Furthermore, the cutter discs are all standard disc cutters; the aperture of the filter grille is 150mm×150mm; the open grille is a short cylindrical type, with an arrangement spacing of 150mm and a height of 200mm.

[0046] If the screw machine is found to be stuck by the crushed steel bars, choose from the following three methods to deal with it: a. Rotate the screw machine forward and reverse to loosen it and return it to the soil bin to continue stirring and mixing with the soil for 5 minutes before resuming unearthing it; b. Use the screw machine to drive the telescopic system, slowly extending and retracting it back and forth to reduce the screw machine's rotational torque; c. If the screw machine is stuck, close the screw machine gate and have a professional open the emergency observation hole on the screw machine for inspection, and then take targeted measures to deal with it.

[0047] Before controlling the shield machine to excavate along the designed route in the soft soil layer, the method further includes the steps of: setting the shield machine construction parameters;

[0048] The construction parameters of the shield machine include: soil bin pressure of 2.0-2.2 bar, shield advancement speed of 2-3 mm / min, cutter head speed of 0.5-0.8 rpm, cutter head average torque ≤2000 KNm, torque fluctuation ≤300 KNm, maximum thrust ≤2500 T, soil bin pressure fluctuation less than ±0.1 bar, shield tail grease filling amount of 80-100 kg per ring, excavation soil loss ≤5‰, excavation volume ≤39.03 m 3 And the amount of cutter disc sealing grease added to each ring should be no less than 4kg.

[0049] By setting the construction parameters, the shield machine can be guaranteed to advance smoothly in soft soil layers; by strictly controlling the quality of the synchronous grouting liquid and the pressure of the soil bin, the ground soil pressure can be accurately balanced, which can reduce the settlement of the soil and the inclination of the bridge.

[0050] Among them, the shield machine construction parameters also include setting the excavation soil layer to under-excavation mode, setting it to under-pressure excavation mode during the excavation process, and setting the uplift value of the soil above the shield incision to no more than 0.5mm.

[0051] Under-pressure excavation can form a soil plug at the excavation port, which plays a good role in sealing, maintaining pressure and preventing blowout, ensuring construction safety. At the same time, it avoids the risk of uncontrollable excavation when the shield directly cuts the pile foundation, shortens the overall construction period, and reduces construction costs. The under-excavation method is adopted, and it is ensured that the soil above the shield incision has a bulge of ≤0.5mm, which can effectively offset the later settlement of part of the soil, avoid ground collapse, and ensure the successful implementation of the cutting construction.

[0052] Wherein, the step S3 further comprises the steps of: synchronous grouting when cutting the pile foundation and the soil;

[0053] After the pile is passed, secondary grouting is carried out and surface monitoring is carried out at any time;

[0054] When the surface settlement is monitored to be within ±2mm / maintained within the range of ±2mm, stop the secondary grouting and continue excavation until the cutting is completed.

[0055] Through simultaneous grouting and secondary grouting, the pipe segments and tunnel soil can be reinforced to reduce the risk of collapse; when excavation is stopped or an emergency occurs, the screw machine outlet gate is closed immediately.

[0056] Specifically, the grouting volume per ring of the synchronous grouting is 7.1m 3 , the grouting pressure is 4.5 bar, the bulk density of each cubic meter of slurry is 1810 kg, the consistency is 120 mm, and the pH is weakly alkaline.

[0057] Furthermore, the synchronous grouting liquid includes: fine sand 820-900kg / m 3 , Grade II fly ash 400-450kg / m 3 , sodium bentonite 40-60kg / m 3 , water 550-600kg / m 3 ; The fine sand modulus is 1.6-2.2; By strictly controlling the quality of the synchronous grouting liquid and the pressure of the soil bin, the soil pressure on the ground can be accurately balanced, which can reduce the settlement of the soil and the inclination of the bridge.

[0058] Wherein, the secondary grouting adopts double slurry, and the double liquid slurry is composed of cement, water glass and water in a weight ratio of 1:0.06:0.8.

[0059] Through the above design, the soil pressure on the ground can be balanced and the risk of soil settlement can be reduced.

[0060] Among them, the process of shield machine excavation also includes the steps of: injecting composite bentonite slurry with a certain viscosity into the soil bin to ensure that the soil bin pressure fluctuation is within the range of ±0.1 bar.

[0061] Specifically, the viscosity of the composite bentonite slurry injected into the soil bin is 35s. The composite bentonite slurry with a viscosity of 35s is used to improve the slag, and the amount of slag improvement added is the amount of composite bentonite slurry added for shield pressure maintenance. By strictly controlling the pressure of the soil bin and accurately balancing the soil pressure on the ground, the settlement of the soil and the inclination of the bridge can be reduced.

[0062] Furthermore, during the shield cutting and excavation process, the soil status at the screw machine outlet is observed at any time. When it is found that the excavated soil is too sparse, the shield advancement is stopped, the excavated samples are taken for analysis, and the injection amount of the composite bentonite slurry is adjusted to the set parameter range.

[0063] Wherein, the construction method also includes: after the tail of the shield machine is out of the pile foundation area, reinforcement grouting is performed through the grouting holes reserved on the pipe segment.

[0064] Specifically, the material for reinforcement grouting is ordinary cement slurry with a water-cement ratio of 1:0.8. The grouting pressure is determined based on geological conditions and water and soil pressure calculations, and the pressure is controlled in combination with ground observation data.

[0065] Wherein, when the shield machine is controlled to excavate along the designed route in the soft soil layer, it excavates according to the settlement control standard of the railway main line;

[0066] The railway mainline settlement control standards are: the railway line uplift per hour ≤2mm, the hourly settlement ≤4mm; the cumulative uplift per day and night ≤4mm, the cumulative settlement per day and night ≤10mm; the horizontal height difference between the two rail tops ≤2mm, the final cumulative uplift of the line within half a year ≤10mm, and the cumulative settlement ≤40mm.

[0067] After the construction of this method was completed, the cumulative settlement of the main line was within the range of -0.7 to +2.3mm, ensuring the normal operation of the tunnel, which has great promotion significance for similar construction.

[0068] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0069] The present invention is described in detail above in conjunction with the embodiments of the accompanying drawings. A person skilled in the art can make various variations of the present invention according to the above description. Therefore, certain details in the embodiments should not constitute a limitation of the present invention, and the scope of protection of the present invention shall be defined by the scope of the attached claims.

Claims

1. A construction method for shield cutting pile foundation, characterized in that: The steps include: S1. Selection of cutter disc and configuration of cutter: S11, use spoke-type cutter disc; S12, a double roller is installed at the center of the cutter disc, a double-edged roller is installed on each spoke on the front of the cutter disc, a row of front scrapers are installed on both sides of each spoke, and a circle of edge scrapers and a circle of tearing knives are installed in sequence from the inside to the outside on the periphery of the cutter disc; S2. Add quarrying boxes and open grilles: S21. A quarrying box is installed in front of the inlet of the slurry pump of the shield machine trailer, and a filter grid is arranged inside the quarrying box; S22, a screw conveyor is arranged at the slurry discharge port of the quarrying box; S23, install two or more open grilles at the mud door positions at the bottom of the mud and water bin and the air cushion bin, and the two or more open grilles are arranged at intervals; S3, start the shield machine, control the shield machine to dig along the designed route in the soft soil layer, drive the double roller cutter, double-edged roller cutter and tearing cutter to cut the pile foundation and soil, and the front scraper and side scraper to scrape the cut pile foundation and soil; S4. During the tunneling process of the shield machine, the steel bars and large slag generated during the cutting process are filtered out by the filter grid inside the quarrying box, and two or more open grids are used to prevent the steel bars and large slag from entering the slag discharge port of the air cushion bin; S5. Start the screw machine regularly to discharge the steel bars and large debris filtered out of the quarrying box.

2. The construction method of shield cutting pile foundation according to claim 1, characterized in that: Before controlling the shield machine to excavate along the designed route in the soft soil layer, the method also includes the steps of: setting the shield machine construction parameters; The construction parameters of the shield machine include: soil bin pressure of 2.0-2.2 bar, shield advancement speed of 2-3 mm / min, cutter head speed of 0.5-0.8 rpm, cutter head average torque ≤2000 KNm, torque fluctuation ≤300 KNm, maximum thrust ≤2500 T, soil bin pressure fluctuation less than ±0.1 bar, shield tail grease filling amount of 80-100 kg per ring, excavation soil loss ≤5‰, excavation volume ≤39.03 m 3 And the amount of cutter disc sealing grease added to each ring should be no less than 4kg.

3. The construction method of shield cutting pile foundation according to claim 2, characterized in that: The shield machine construction parameters also include setting the excavation soil layer to an under-excavation mode, setting it to an under-pressure excavation mode during the excavation process, and setting the uplift value of the soil above the shield incision to no more than 0.5 mm.

4. The construction method of shield cutting pile foundation according to claim 1, characterized in that: The step S3 also includes the steps of: synchronous grouting when cutting the pile foundation and the soil; After the pile is passed, secondary grouting is carried out and surface monitoring is carried out at any time; When the surface settlement is monitored to be within ±2mm / maintained within the range of ±2mm, stop the secondary grouting and continue excavation until the cutting is completed.

5. The construction method of shield cutting pile foundation according to claim 4, characterized in that: The secondary grouting uses double slurry, and the double slurry is composed of cement, water glass and water in a weight ratio of 1:0.06:0.

8.

6. The construction method of shield cutting pile foundation according to claim 1, characterized in that: The shield machine excavation process also includes the following steps: injecting composite bentonite slurry with a certain viscosity into the soil bin to ensure that the soil bin pressure fluctuation is within the range of ±0.1 bar.

7. The construction method of shield cutting pile foundation according to claim 1, characterized in that: The construction method further comprises: after the shield tail of the shield machine is out of the pile foundation area, reinforcing grouting is performed through the grouting holes reserved on the pipe segment.

8. The construction method of shield cutting pile foundation according to claim 1, characterized in that: When the controlled shield machine excavates along the designed route in the soft soil layer, it excavates according to the railway mainline settlement control standard.

9. The construction method of shield cutting pile foundation according to claim 8, characterized in that: The railway mainline settlement control standards are: the railway line uplift per hour ≤2mm, the hourly settlement ≤4mm; the cumulative uplift per day and night ≤4mm, the cumulative settlement per day and night ≤10mm; the horizontal height difference between the two rail tops ≤2mm, the final cumulative uplift of the line within half a year ≤10mm, and the cumulative settlement ≤40mm.

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