A load-unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel

Abstract

A method for unloading and balancing the construction of a newly built rectangular jacking pipe passing through an existing subway tunnel, including the following steps: arranging deformation monitoring points of the existing tunnel; calculating the excavation influence range; measuring and setting out, installing the jacking machine frame, backrest, and main jacking device, equipment debugging, and the jacking machine entering the tunnel; hanging and placing cushion blocks and pipe sections; jacking and measuring; injecting soil consolidation slurry; monitoring the deformation of the existing tunnel; judging the maximum uplift value of the tunnel, and deciding whether to take ballasting measures according to whether the maximum vertical displacement value of the arch of the existing tunnel is greater than or equal to the set warning value; stacking and weighting; and the jacking machine exiting the tunnel. The present invention takes targeted deformation control measures for the existing tunnel based on the calculated excavation influence range and the dynamic monitoring results of the tunnel deformation, avoiding the loss of manpower and material resources caused by blind control; according to the unloading balance method, the pipe sections are stacked and weighted to balance the unloading stress generated by the soil layer below, which can effectively achieve the purpose of controlling the deformation of the existing tunnel; the construction efficiency is high and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the technical field of subway shield tunnels, and specifically relates to a load-unloading balance construction method for a newly-built rectangular jacking pipe passing through an existing subway tunnel, and is particularly suitable for a rectangular jacking pipe passing through an existing subway tunnel project in soft soil areas where deformation of the existing tunnel needs to be strictly controlled. Background Art

[0002] With the continuous improvement of the urban underground transportation network, it is inevitable to encounter the problem of building a new rectangular jacking tunnel over the existing subway tunnel in the limited urban underground space. Since the weight of the excavated soil is much greater than the weight of the installed pipe segment, the jacking excavation will produce an unloading effect, which will cause the existing subway tunnel below to bulge and deform as a whole or locally, and then cause a series of diseases such as pipe segment damage and water seepage, joint opening, and longitudinal uneven settlement in the shield tunnel structure below. In severe cases, it will lead to major safety accidents such as locomotive derailment. During the construction of the urban underground rectangular jacking tunnel, the traditional construction method is to reinforce the strata around the existing tunnel in advance. This reinforcement method is very costly in the project. Therefore, how to develop a new construction process that is suitable for the construction of a new rectangular jacking tunnel above the existing subway tunnel on the basis of ensuring the normal and safe operation of the existing subway tunnel and controlling the deformation of the surrounding soil has extremely high social and economic benefits. Summary of the invention

[0003] The technical problem to be solved by the present invention is, in view of the above-mentioned problems existing in the existing jacking tunnel excavation, to provide a load-unloading balance construction method for a newly built rectangular jacking tunnel passing through an existing subway tunnel, so as to effectively control the deformation of the existing subway tunnel during the construction of the newly built rectangular jacking tunnel, and avoid the loss of manpower and material resources caused by blind control; the construction efficiency is high and the cost is low.

[0004] The technical solution adopted by the present invention to solve the above technical problems is:

[0005] A load-unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel comprises the following steps:

[0006] S1. Arrange deformation monitoring points of existing tunnels;

[0007] S2. Calculate the excavation influence range, regard the existing tunnel as a Timoshenko beam model placed on the Pasternak foundation, and obtain the main range of the existing tunnel longitudinal deformation affected by the new jacking tunnel;

[0008] S3, measurement and setting out, installation of the pipe jacking machine frame, backrest, main jacking device, equipment debugging, and entry of the pipe jacking machine into the hole;

[0009] S4, hanging pads and pipe joints;

[0010] S5. Pipe jacking and measurement;

[0011] S6. Pressurize soil consolidation slurry. When the jacking pipe is pushed forward, the consolidation slurry is promptly injected through the grouting holes on the pipe wall, so that the slurry penetrates into the soil layer around the jacking pipe and hardens in the soil layer, thereby strengthening the soil layer.

[0012] S7. Deformation monitoring of existing tunnels;

[0013] S8, judging the maximum uplift value of the tunnel, before the excavation face enters the main impact area, if the maximum vertical displacement value of the existing tunnel vault monitored is less than the set warning value, no ballast measures are taken for the pipe section, and whether to take ballast measures is subsequently determined based on whether the maximum vertical displacement value of the existing tunnel vault monitored during the jacking process is greater than or equal to the set warning value; if no ballast measures are taken, repeating steps S4 to S7 until the jacking machine exits the tunnel in step S10;

[0014] S9, ballast weight: before the excavation face enters the main impact area or during the subsequent excavation process, if the maximum vertical displacement value of the existing tunnel vault obtained by monitoring is greater than or equal to the set warning value, then take ballasting measures on the pipe segment;

[0015] S10. When the machine head reaches the receiving well, the pipe jacking machine exits the hole.

[0016] According to the above scheme, step S1 is specifically as follows: 1 to 2 months before the formal construction of the jacking pipe, deformation monitoring points are arranged on the existing subway tunnel. The deformation monitoring section arrangement range of the existing subway tunnel is 60m to the left and right of the intersection of the new and old tunnel planes. The arrangement spacing is 5m, 10m, and 20m from both sides of the jacking pipe axis. A total of 5 prisms are arranged in each section, among which the first prism is arranged at the top of the section center to monitor the vertical displacement of the tunnel vault; the second and third prisms are arranged at both ends of the horizontal axis of the section to monitor the convergence of the tunnel clearance; the fourth and fifth prisms are arranged on the roadbed, respectively, to monitor the horizontal displacement and vertical displacement of the roadbed, respectively.

[0017] According to the above scheme, step S2 is specifically as follows: using the Mindlin solution and the finite difference method to calculate the variation diagram of the maximum uplift value of the existing tunnel with the excavation distance, and defining the interval with no significant change in the uplift value as the secondary influence area, and the interval with significant change as the primary influence area, specifically: the excavation surface within the range of 3 times the width of the newly built jacking pipe from the axis of the existing tunnel is the primary influence area, and the range outside the range of 3 times the width of the newly built jacking pipe is the secondary influence area.

[0018] According to the above scheme, the pipe jacking machine entering the hole in step S3 is specifically as follows: after completing the measurement and layout, installing the pipe jacking machine frame, backrest, main jacking device, equipment debugging, and breaking the hole door, the pipe jacking machine is operated to enter the hole; hoisting and placing cushion blocks and pipe sections is specifically as follows: after the pipe jacking jack pushes in a pipe section, the cushion blocks and pipe sections are hoisted and placed in time, and a new pipe section is installed.

[0019] According to the above scheme, the step S5 of pipe jacking and measurement is specifically as follows:

[0020] Pipe jacking speed v The secondary impact area calculated in step S2 is controlled at 3.5~4m / d, the primary impact area is controlled at 2~3m / d, and the thrust force is F According to the calculation formula (1) based on the engineering situation, the remaining construction parameters need to be dynamically adjusted according to the feedback data of surface and tunnel deformation to achieve the best state:

[0021] F = F 1+ F twenty one)

[0022] Where: F is the minimum top force, in kN; F 1 is the friction between the pipe and the soil layer, in kN, F 1=(a+b)×2 Lf , L is the jacking length of the jacking pipe, in m; f It is the average friction between the outer wall of the pipe and the soil, in kN / m 2 , take 7~12 kN / m 2 ; F 2 is the head-on resistance of the pipe jacking machine, in kN, F 2= a × B R 1, R 1 is the passive earth pressure at the lower 1 / 3 of the pipe jacking machine, in kN; a is the width of the pipe jacking machine, in m; b It is the height of pipe jacking machine, in m.

[0023] According to the above scheme, the grouting sequence of the soil consolidation slurry in step S6 is specifically: ground mixing → starting the grouting pump → opening the main pipe valve → opening the pipe segment valve → delivering slurry → closing the pipe segment valve → closing the main pipe valve → disassembling the quick connector in the well → lowering the pipe segment → connecting the 2-inch main pipe → repeating the cycle; grouting materials and proportions: the cementitious material uses P042.5 cement, and the slurry ratio is controlled within the following range: 0.5:1~1:1.

[0024] According to the above scheme, the deformation monitoring of the existing tunnel in step S7 is specifically as follows: during the jacking process, the deformation of the existing shield tunnel is monitored using an intelligent total station; when the jacking excavation surface is in the secondary impact area, the monitoring frequency is 1 to 2 times / day; when the jacking excavation surface is in the primary impact area, the monitoring frequency is 3 to 4 times / day.

[0025] According to the above scheme, the warning value setting range in step S8 and step S9 is 3~5mm.

[0026] According to the above scheme, the specific steps of taking ballasting measures on the pipe joint in step S9 are:

[0027] S91. If the ballast is implemented before the jacking excavation face enters the main impact area, after the jacking machine excavates the capacity of a pipe section in the soil in front of the tunnel each time, the weight difference between the excavated soil and the pipe section is calculated in time, and the pipe sections in the main impact area are ballasted with prefabricated C20 plain concrete or iron blocks of the same weight difference; after the soil of each pipe section is excavated and ballasted, the subsequent soil excavation work is carried out; when the ballasted pipe section leaves the main impact area, the plain concrete or iron blocks used for ballasting are moved to the subsequent pipe section entering the main impact area;

[0028] S92. If heap loading is implemented during the subsequent excavation process, all pipe sections in the main impact area are immediately loaded and weighed. The specific steps are consistent with the above step S91.

[0029] According to the above scheme, the step S10 of the pipe jacking machine exiting the hole specifically includes two situations:

[0030] S101. If no ballast measures are taken during the whole process of pipe jacking, the pipe jacking machine shall be disassembled and hoisted out of the receiving well, and then slurry replacement, removal of equipment inside the pipe, caulking, cleaning, and joint treatment shall be carried out;

[0031] S102. If ballasting measures are taken for the jacking pipe, the soil layer in the main impact area is reinforced by grouting through the grouting holes of the pipe sections after the jacking pipe is fully penetrated; after grouting reinforcement, the piled objects are removed section by section, and the deformation of the existing tunnel is monitored simultaneously. If the deformation of the existing tunnel is stable after the removal of each section of the piled objects, the next section of the heavy objects is removed until all the heavy objects are removed. If the deformation is unstable, grouting is continued or other ground reinforcement measures are taken until the removal of the piled objects does not affect the subsequent deformation of the tunnel; after the deformation of the tunnel is stable, the jacking machine is disassembled and hoisted out of the receiving well and subsequent work is carried out.

[0032] The beneficial effects of the present invention are as follows:

[0033] 1. Taking targeted deformation control measures for existing tunnels based on the calculated excavation impact range and the dynamic monitoring results of tunnel deformation can avoid the loss of manpower and material resources caused by blind control;

[0034] 2. According to the unloading balance method, the pipe segments are loaded and weighed to balance the unloading stress generated by the soil layer below, which can effectively achieve the purpose of controlling the deformation of the existing tunnel;

[0035] 3. The construction method is simple, the operation is easy, the construction efficiency is high and the cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flow chart of a load-unloading balance construction method for a newly-built jacking pipe passing through an existing subway tunnel according to an embodiment of the present invention;

[0037] Figure 2 is a diagram of the arrangement of deformation monitoring points of the existing shield tunnel section in an embodiment of the present invention;

[0038] Figure 3 It is a calculation model of the influence range of new pipe jacking excavation in the embodiment of the present invention;

[0039] Figure 4 It is the main impact area of ​​the new pipe jacking excavation in the embodiment of the present invention. DETAILED DESCRIPTION

[0040] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0041] The present invention discloses a method for unloading and balancing a newly built jacking pipe through an existing subway tunnel, including arranging deformation monitoring points of the existing tunnel, calculating the excavation impact range, the jacking machine entering the tunnel, hanging and placing cushion blocks and pipe sections, jacking and measuring the jacking pipe, injecting soil consolidation slurry, deformation monitoring of the existing tunnel, determining the maximum uplift value of the tunnel, stacking and weighing, and the jacking machine exiting the tunnel. The flow chart of the whole method is as follows Figure 1 As shown, the specific steps include:

[0042] Step 1: Arrange deformation monitoring points in existing tunnels

[0043] Deformation monitoring points are arranged in the existing subway tunnel 1 to 2 months before the formal construction of the jacking pipe. The deformation monitoring section of the existing subway tunnel is arranged within 60m on the left and right sides of the intersection of the new and old tunnel planes. The arrangement spacing is 5m, 10m, and 20m on both sides of the jacking axis of the jacking pipe. A total of 5 prisms are arranged in each section. Prism A is used to monitor the vertical displacement of the tunnel vault, prisms B and C are used to monitor the convergence of the tunnel clearance, prism D is used to monitor the horizontal displacement of the roadbed, and prism E is used to monitor the vertical displacement of the roadbed. The tunnel section deformation monitoring points are arranged as follows: Figure 2 shown.

[0044] Step 2: Calculate the impact range of excavation

[0045] The impact of rectangular pipe jacking construction on the existing tunnel changes dynamically with the excavation distance of the excavation face. Before pipe jacking excavation, the excavation impact range is calculated by combining engineering data and theoretical methods. The existing tunnel is regarded as a Timoshenko beam model placed on the Pasternak foundation. The excavation impact range calculation model is as follows: Figure 3As shown. The Mindlin solution and finite difference method are used to calculate the variation of the maximum uplift value of the existing tunnel with the excavation distance. The interval with no significant change in the uplift value is defined as the secondary influence area, and the interval with significant change is defined as the main influence area. For the detailed calculation process, please refer to the literature: Liang R, Kang C, Xiang L, Li Z, Lin C, Gao K, Guo Y, 2021. Responses of in-service shieldtunnel to overcrossing tunnelling in soft ground. Environmental EarthSciences. 80(5), 1-15. Theoretical and a large number of measured results show that the excavation surface within 3 times the width of the new jacking pipe from the existing tunnel axis is the main influence area, and the area outside 3 times the width of the new jacking pipe is the secondary influence area. The main influence area of ​​the new tunnel excavation is as follows: Figure 4 shown.

[0046] Step 3: Pipe jacking machine enters the hole

[0047] After completing the measurement and layout, installing the pipe jacking machine frame, backrest, main jacking device, equipment debugging, and breaking the hole door, operate the pipe jacking machine to enter the hole.

[0048] Step 4: Lifting pads and pipe joints

[0049] After the pipe jacking jack pushes in a pipe section, the pads and pipe sections should be hoisted in time, and the new pipe section should be installed.

[0050] Step 5: Pipe jacking and measurement

[0051] Pipe jacking speed v The secondary impact area calculated in step 2 is controlled at 3.5~4m / d, and the primary impact area is controlled at 2~3m / d. F Based on the engineering situation, the calculation is performed according to formula (1). The remaining construction parameters need to be dynamically adjusted according to the surface and tunnel deformation feedback data to achieve the optimal state.

[0052] During the jacking process, the jacking axis is closely controlled. After each section of the pipe is jacked, the posture of the machine head is measured. Once the machine head has a slight turning angle, measures such as reversing the cutter head and adding pressure iron are immediately taken to correct it. The jacking machine excavates the pipe in the form of a screw conveyor + track soil box + winch + crawler crane. During the jacking process, the excavation volume of each section is counted as accurately as possible, and efforts are made to keep it consistent with the theoretical excavation volume, avoid over-excavation or under-excavation, ensure the relative stability of the front soil, and reduce disturbance to the stratum. During the jacking process, the jacking distance of the jacking pipe is closely monitored through the total station behind the starting well, and the jacking distance is recorded and compared with the excavation influence range. As the jacking pipe continues to be excavated, the frequency of monitoring the jacking distance is gradually increased, with 1~2 measurements per day in the secondary influence area and 3~4 measurements per day in the main influence area, so as to timely determine the influence area where the jacking pipe excavation surface is located.

[0053] Step 6: Inject soil consolidation slurry

[0054] When the pipe is pushed forward, the consolidation slurry is timely injected through the grouting holes on the pipe wall, so that the slurry penetrates into the soil layer around the pipe and hardens in the soil layer, thereby achieving the effect of reinforcing the soil layer. Grouting sequence: ground mixing → start the grouting pump → open the main pipe valve → open the pipe section valve → send slurry → close the pipe section valve → close the main pipe valve → disassemble the quick connector in the well → lower the pipe section → connect the 2-inch main pipe → repeat the cycle. Grouting materials and proportions: P042.5 cement is used as the cementitious material. The appropriate slurry proportion can not only increase the diffusion and reinforcement range of the slurry but also control the gelling time of the slurry. The slurry proportion should be controlled within the following range: 0.5:1~1:1.

[0055] Step 7: Existing tunnel deformation monitoring

[0056] During the jacking process, the deformation of the existing shield tunnel is monitored using an intelligent total station; when the jacking excavation face is in the secondary impact area, the monitoring frequency is 1 to 2 times per day, and when the jacking excavation face is in the primary impact area, the monitoring frequency is 3 to 4 times per day.

[0057] Step 8: Determine the maximum uplift value of the tunnel

[0058] Before the excavation face enters the main impact area, if the maximum vertical displacement value of the existing tunnel vault obtained by monitoring is less than the set warning value, and the warning value setting range is 3~5mm (the warning value is set to 3mm in the embodiment), then there is no need to take ballast measures for the pipe section. Subsequently, whether to take ballast measures is determined based on whether the maximum vertical displacement value of the existing tunnel vault obtained by monitoring during the pipe jacking process is greater than or equal to the set warning value. If no ballast measures are required, repeat steps 4 to 7 until the pipe jacking machine exits the hole in step 10.

[0059] Step 9: Loading and Ballasting

[0060] Before the top pipe excavation face enters the main impact area or during the subsequent excavation process, if the maximum vertical displacement value of the existing tunnel vault obtained by monitoring is greater than or equal to the set warning value, it is necessary to take ballasting measures for the pipe segment. If the top pipe excavation face is implemented before entering the main impact area, the weight difference between the excavated soil and the pipe segment is calculated in time after the top pipe machine excavates the capacity of a pipe segment in front of the tunnel each time, and the prefabricated C20 plain concrete or iron blocks with the same weight difference are used to carry out the pile loading and weighting of the pipe segment in the main impact area. In order to facilitate the subsequent transportation, the plain concrete is divided into layers and blocks with a size of 1m×4m×0.5m by nine plywood. It is transported out in the later stage with the help of pulleys and cranes. The plain concrete is placed on both sides of the pipe segment track to avoid affecting the passage of the pulleys. After the soil of each pipe segment is excavated and the pile loading and weighting are completed, the subsequent soil excavation work can be carried out. When the ballasted pipe section leaves the main impact area, the plain concrete or iron blocks used for ballasting should be moved to the pipe section that enters the main impact area later. If heap loading is implemented during the subsequent excavation process, all pipe sections in the main impact area should be immediately loaded, and the steps are the same as above.

[0061] Step 10: Pipe Jacking Machine Out of the Hole

[0062] If no ballasting measures are taken during the entire process of pipe jacking, the pipe jacking machine shall be disassembled and hoisted out of the receiving well, followed by slurry replacement, removal of equipment inside the pipe, caulking, cleaning, and joint processing.

[0063] Step 11: Soil reinforcement in the main affected areas

[0064] If ballasting measures are taken for the jacking pipe, the soil layer in the main impact area will be reinforced by grouting through the grouting holes of the pipe sections after the jacking pipe is fully penetrated.

[0065] Step 12: Remove the stacked items

[0066] After grouting reinforcement, the piled load is removed section by section, and the deformation of the existing tunnel is monitored simultaneously. If the deformation of the existing tunnel is stable after each section of the piled load is removed, the next section of the piled load is removed until all of them are removed. If the deformation is unstable, grouting is continued or other ground reinforcement measures are taken until the removal of the heavy objects will not affect the subsequent deformation of the tunnel. After the deformation of the tunnel is stable, the subsequent work after the pipe jacking machine is hoisted out of the receiving well in step 10 can be carried out.

[0067] The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments. All technical solutions under the concept of the present invention belong to the protection scope of the present invention. It should be pointed out that for ordinary technicians in this technical field, some improvements and modifications without departing from the principle of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A method for unloading and balancing a newly built rectangular jacking pipe passing through an existing subway tunnel, characterized in that: The following steps are involved: S1. Arrange deformation monitoring points of existing tunnels; S2. Calculate the excavation influence range, regard the existing tunnel as a Timoshenko beam model placed on the Pasternak foundation, and obtain the main range of the existing tunnel longitudinal deformation affected by the new jacking tunnel. Specifically, use the Mindlin solution and finite difference method to calculate the maximum uplift value of the existing tunnel as a function of excavation distance. Define the interval with no significant change in uplift value as the secondary influence area, and define the interval with significant change as the primary influence area. Specifically, the excavation surface within the range of 3 times the new jacking pipe width from the existing tunnel axis is the primary influence area, and the area outside the range of 3 times the new jacking pipe width is the secondary influence area. S3, measurement and setting out, installation of the pipe jacking machine frame, backrest, main jacking device, equipment debugging, and entry of the pipe jacking machine into the hole; S4, hanging pads and pipe joints; S5. Pipe jacking and measurement, specifically: Pipe jacking speed v The secondary impact area calculated in step S2 is controlled at 3.5~4m / d, the primary impact area is controlled at 2~3m / d, and the thrust force is F According to the calculation formula (1) based on the engineering situation, the remaining construction parameters need to be dynamically adjusted according to the feedback data of surface and tunnel deformation to achieve the best state: F = F 1+ F 2 （1） Where: F is the minimum top force, in kN; F 1 is the friction between the pipeline and the soil layer, unit is kN, F 1=(a+b)×2 Lf , L is the jacking length of the jacking pipe, in m; f It is the average friction between the outer wall of the pipe and the soil, in kN / m 2 , take 7~12 kN / m 2 ; F 2 is the head-on resistance of the pipe jacking machine, in kN, F 2= a × B R 1, R 1 is the passive earth pressure at the lower 1 / 3 of the pipe jacking machine, in kN; a is the width of the pipe jacking machine, in m; b is the height of the pipe jacking machine, in m; S6. Pressurize soil consolidation slurry. When the jacking pipe is pushed forward, the consolidation slurry is promptly injected through the grouting holes on the pipe wall, so that the slurry penetrates into the soil layer around the jacking pipe and hardens in the soil layer, thereby strengthening the soil layer. S7. Deformation monitoring of existing tunnels; S8, judging the maximum uplift value of the tunnel, before the excavation face enters the main impact area, if the maximum vertical displacement value of the existing tunnel vault monitored is less than the set warning value, no ballast measures are taken for the pipe section, and whether to take ballast measures is subsequently determined based on whether the maximum vertical displacement value of the existing tunnel vault monitored during the jacking process is greater than or equal to the set warning value; if no ballast measures are taken, repeating steps S4 to S7 until the jacking machine exits the tunnel in step S10; S9, ballast weight: before the excavation face enters the main impact area or during the subsequent excavation process, if the maximum vertical displacement value of the existing tunnel vault obtained by monitoring is greater than or equal to the set warning value, then take ballasting measures on the pipe segment; S10. When the machine head reaches the receiving well, the pipe jacking machine exits the hole.

2. The unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel according to claim 1 is characterized in that: The step S1 is specifically as follows: 1 to 2 months before the formal construction of the jacking pipe, deformation monitoring points are arranged on the existing subway tunnel. The deformation monitoring section arrangement range of the existing subway tunnel is 60m to the left and right of the intersection of the new and old tunnel planes. The arrangement spacing is 5m, 10m, and 20m from both sides of the jacking pipe axis. A total of 5 prisms are arranged in each section, among which the first prism is arranged at the top of the section center to monitor the vertical displacement of the tunnel vault; the second and third prisms are arranged at both ends of the horizontal axis of the section to monitor the convergence of the tunnel clearance; the fourth and fifth prisms are arranged on the roadbed, respectively, to monitor the horizontal displacement and vertical displacement of the roadbed, respectively.

3. The unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel according to claim 1 is characterized in that: In step S3, the pipe jacking machine enters the hole specifically as follows: after completing the measurement and layout, installing the pipe jacking machine frame, backrest, main jacking device, equipment debugging, and breaking the hole door, the pipe jacking machine is operated to enter the hole; hoisting and placing the cushion block and pipe section specifically as follows: after the pipe jacking jack pushes in a pipe section, the cushion block and pipe section are hoisted and placed in time, and a new pipe section is installed.

4. The unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel according to claim 1 is characterized in that: The grouting sequence of the soil consolidation slurry in step S6 is specifically: mixing slurry on the ground → starting the grouting pump → opening the main pipe valve → opening the pipe segment valve → delivering slurry → closing the pipe segment valve → closing the main pipe valve → disassembling the quick connector in the well → lowering the pipe segment → connecting the 2-inch main pipe → repeating the cycle; grouting materials and proportions: the cementitious material uses P042.5 cement, and the slurry proportion is controlled within the following range: 0.5:1~1:

1.

5. The unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel according to claim 1 is characterized in that: The step S7 of existing tunnel deformation monitoring is specifically as follows: during the jacking process, the deformation of the existing shield tunnel is monitored using an intelligent total station; when the jacking excavation surface is in the secondary impact area, the monitoring frequency is 1 to 2 times / day; when the jacking excavation surface is in the primary impact area, the monitoring frequency is 3 to 4 times / day.

6. The unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel according to claim 1 is characterized in that: The warning value setting range in step S8 and step S9 is 3-5 mm.

7. The unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel according to claim 1 is characterized in that: The specific steps of taking ballasting measures on the pipe joint in step S9 are: S91. If the ballast is implemented before the jacking excavation face enters the main impact area, after the jacking machine excavates the capacity of a pipe section in the soil in front of the tunnel each time, the weight difference between the excavated soil and the pipe section is calculated in time, and the pipe sections in the main impact area are ballasted with prefabricated C20 plain concrete or iron blocks of the same weight difference; after the soil of each pipe section is excavated and ballasted, the subsequent soil excavation work is carried out; when the ballasted pipe section leaves the main impact area, the plain concrete or iron blocks used for ballasting are moved to the subsequent pipe section entering the main impact area; S92. If heap loading is implemented during the subsequent excavation process, all pipe sections in the main impact area are immediately loaded and weighed. The specific steps are consistent with the above step S91.

8. The unloading balance construction method for a newly built rectangular jacking pipe passing through an existing subway tunnel according to claim 1 is characterized in that: The step S10 of the pipe jacking machine exiting the hole specifically includes two situations: S101. If no ballast measures are taken during the whole process of pipe jacking, the pipe jacking machine shall be disassembled and hoisted out of the receiving well, and then slurry replacement, removal of equipment inside the pipe, caulking, cleaning, and joint treatment shall be carried out; S102. If ballasting measures are taken for the jacking pipe, the soil layer in the main impact area is reinforced by grouting through the grouting holes of the pipe sections after the jacking pipe is fully penetrated; after grouting reinforcement, the piled objects are removed section by section, and the deformation of the existing tunnel is monitored simultaneously. If the deformation of the existing tunnel is stable after the removal of each section of the piled objects, the next section of the heavy objects is removed until all the heavy objects are removed. If the deformation is unstable, grouting is continued or other ground reinforcement measures are taken until the removal of the piled objects does not affect the subsequent deformation of the tunnel; after the deformation of the tunnel is stable, the jacking machine is disassembled and hoisted out of the receiving well and subsequent work is carried out.

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