CN115306397A - Unloading balance construction method for newly-built rectangular pipe-jacking upward-penetrating existing subway tunnel - Google Patents

Abstract

An unloading balance construction method for a newly-built rectangular pipe jacking upward-penetrating existing subway tunnel comprises the following steps: arranging existing tunnel deformation monitoring points; calculating an excavation influence range; measuring and lofting, installing a push bench rack, a rear support device and a main jacking device, debugging equipment and entering a tunnel by the push bench; hoisting the cushion block and the pipe joint; jacking and measuring a jacking pipe; pressing and injecting soil consolidation slurry; monitoring the deformation of the existing tunnel; judging the maximum uplift value of the tunnel, and determining whether ballast measures are taken or not according to whether the vertical displacement value of the maximum vault of the existing tunnel is greater than or equal to a set early warning value or not; stacking and loading the weight; and (4) discharging the pipe jacking machine. According to the method, targeted deformation control measures are taken for the existing tunnel according to the calculated excavation influence range and the tunnel deformation dynamic monitoring result, so that the loss of manpower and material resources caused by blind control is avoided; according to an unloading balance method, the pile-loading pressure weight of the pipe sections is balanced to balance the unloading stress generated by the soil layer below, so that the aim of controlling the deformation of the existing tunnel can be effectively fulfilled; high construction efficiency and low cost.

Description

A construction method for unloading and balancing construction of a newly built rectangular pipe jacking through an existing subway tunnel

technical field

The invention belongs to the technical field of subway shield tunnels, and in particular relates to a construction method for unloading balance of a new rectangular pipe jacking on an existing subway tunnel, and is especially suitable for a rectangular pipe jacking on top of an existing tunnel in soft soil areas where the deformation of the existing tunnel needs to be strictly controlled. There are subway tunnel projects.

Background technique

With the continuous improvement of the urban underground transportation network, in the limited urban underground space, it is inevitable to encounter the problem that the new rectangular jacking pipe will pass through the existing subway tunnel. Because the weight of the excavated soil is much greater than the weight of the installed pipe joints, the pipe jacking excavation will produce an unloading effect, which will cause the overall or local uplift deformation of the existing subway tunnel below, and then cause the shield tunnel structure below to produce such as A series of diseases such as segment damage and water seepage, joint opening, and longitudinal uneven settlement, etc., will lead to major safety accidents such as locomotive derailment in severe cases. During the construction process of urban underground rectangular pipe-jacking tunnels, the traditional construction method is to reinforce the surrounding strata of the existing tunnels in advance. This reinforcement method is very costly in the project. On the basis of soil deformation, the development of a new construction technology suitable for the construction of new rectangular pipe jacking above the existing subway tunnel has extremely high social and economic benefits.

Contents of the invention

The technical problem to be solved by the present invention is to provide a new rectangular pipe jacking construction method for unloading and balancing construction of the existing subway tunnel, which can effectively control the construction of the newly built rectangular pipe jacking tunnel. The deformation of the existing subway tunnel can be avoided, and the loss of manpower and material resources caused by blind control can be avoided; the construction efficiency is high and the cost is low.

The technical scheme that the present invention adopts for solving the problems of the technologies described above is:

A construction method for unloading balance of a new rectangular jacking pipe passing through an existing subway tunnel, comprising the following steps:

S1. Arrange deformation monitoring points of existing tunnels;

S2. Calculate the scope of impact of excavation, regard the existing tunnel as a Timoshenko beam model placed on the Pasternak foundation, and obtain the main scope of the longitudinal deformation of the existing tunnel affected by the new pipe-jacking tunnel;

S3. Measurement and setting out, installation of the pipe jacking machine frame, backrest, and main jacking device, equipment debugging, and the pipe jacking machine entering the hole;

S4, hoisting pads and pipe joints;

S5. Pipe jacking and measurement;

S6. Pressure injection of soil consolidation grout, during pipe jacking, pressure injection of consolidation grout through the pipe wall grouting hole in time, so that the grout penetrates into the soil layer around the pipe jacking 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 surface enters the main affected area, if the monitored maximum vertical displacement value of the existing tunnel vault is less than the set early warning value, no ballasting measures will be taken for the pipe joints. Follow-up According to whether the maximum vertical displacement value of the existing tunnel vault that is monitored during the pipe jacking process is greater than or equal to the set early warning value, it is decided whether to take ballast measures; if no ballast measures are taken, repeat steps S4 to S7 until step S10 pipe jacking machine out of the hole;

S9. Heap load and ballast. When the excavation face enters the main affected area or during the subsequent excavation process, if the monitored maximum vertical displacement value of the existing tunnel vault is greater than or equal to the set early warning value, the tunnel take ballast measures;

S10. When the machine head arrives at the receiving shaft, the pipe jacking machine goes out of the hole.

According to the above plan, the step S1 specifically includes: arranging deformation monitoring points for existing subway tunnels 1 to 2 months before the official construction of pipe jacking, and the layout range of deformation monitoring sections of existing subway tunnels is 60m from the left and right sides of the plane intersection point of the old and new tunnels Scope, the layout distance is arranged according to 5m, 10m, 20m from both sides of the pipe jacking axis, and 5 prisms are arranged in each section, of which the first prism is arranged at the top of the center of the section to monitor the vertical Displacement; 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 respectively arranged on the ballast bed to monitor the horizontal displacement and vertical displacement of the ballast bed respectively.

According to the above scheme, the step S2 is specifically: using the Mindlin solution and the finite difference method to calculate the change diagram of the maximum uplift value of the existing tunnel with the excavation distance, and define the interval where the uplift value has no significant change as the secondary influence area, which has significant The changed interval is defined as the main impact area, specifically: the excavation surface is within 3 times the width of the newly-built pipe jacking from the existing tunnel axis as the main impact area, and the area outside 3 times the width of the newly-built pipe jacking is the secondary impact area.

According to the above scheme, the pipe jacking machine entering the hole in the step S3 is as follows: to complete the measurement and setting out, install the pipe jacking machine frame, backrest, and main jacking device, equipment debugging, and operate the pipe jacking machine to enter the hole after the hole is broken. ; Lifting pads and pipe joints are specifically as follows: After a pipe joint is pushed in by the pipe jacking jack, the pads and pipe joints are lifted in time, and a new pipe joint is installed.

According to the above scheme, the pipe jacking and measurement of the step S5 are specifically:

The pipe jacking speed v is controlled at 3.5-4m/d in the secondary influence area calculated in step 2, and is controlled at 2-3m/d in the main influence area. The jacking force F is combined with the engineering situation according to the formula (1) calculation, and the remaining construction parameters need to be dynamically adjusted according to the feedback data of the surface and tunnel deformation to achieve the best state:

F＝F ₁ +F ₂ (1)

In the formula: F is the minimum jacking force, the unit is kN; F ₁ is the frictional resistance between the pipeline and the soil layer, the unit is kN, F ₁ = (a+b)×2Lf, L is the pipe jacking length, the unit is m; f is The average frictional resistance between the outer wall of the pipeline and the soil, in kN/m ² , should be 7~12kN/m ² ; F ₂ is the head-on resistance of the pipe jacking machine, in kN, F ₂ =a×bR ₁ , R ₁ is the pipe jacking Passive earth pressure at the lower 1/3 of the 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.

According to the above scheme, the grouting sequence of the pressure-injected soil consolidation grout in step S6 is specifically: ground grouting → start the grouting pump → open the main pipe valve → open the pipe joint valve → send slurry → close the pipe joint valve → main pipe Close the valve → disassemble the quick joint in the well → lower the pipe joint → connect the 2-inch main pipe → repeat the cycle; grouting material and proportion: the cementitious material is P042.5 cement, and the proportion of the slurry is controlled within the following range: 0.5:1 ~1:1.

According to the above scheme, the deformation monitoring of the existing tunnel in the step S7 is specifically: during the pipe jacking process, the deformation of the existing shield tunnel is monitored using an intelligent total station; when the pipe jacking excavation surface is in the secondary In the affected area, the monitoring frequency is 1-2 times/day; when the pipe jacking excavation surface is in the main affected area, the monitoring frequency is 3-4 times/day.

According to the above solution, the setting range of the warning value in the steps S8 and S9 is 3-5 mm.

According to the above scheme, the specific steps for taking ballast measures to the pipe joints in the step S9 are:

S91. If stacking and ballasting is carried out before the excavation surface of the pipe jacking enters the main affected area, after the pipe jacking machine excavates the capacity of a pipe joint in the soil in front of the tunnel each time, the excavated soil and pipe joints will be calculated in time. If the weight difference of the joints is different, the prefabricated C20 plain concrete or iron blocks with the same weight difference shall be used to carry out heap ballasting on the pipe joints in the main influence area; after the excavation of the soil body of each pipe joint until the heap ballasting is completed, When the ballasted pipe joint leaves the main impact area, the plain concrete or iron block used for ballasting is moved to the subsequent pipe joint that enters the main impact area;

S92. If stacking is implemented in the subsequent excavation process, immediately perform stacking and ballasting on all pipe joints in the main influence area, and the specific steps are consistent with the above step S91.

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

S101. If ballasting measures are not taken during the whole process of pipe jacking, the pipe jacking machine shall be disassembled and hoisted out of the receiving well, followed by grout replacement, removal of equipment in the pipe, caulking, cleaning, and joint treatment;

S102. If ballasting measures are taken for the pipe jacking, the soil layer in the main affected area shall be grouted and reinforced through the grouting holes of the pipe joints after the pipe jacking is fully penetrated; Simultaneously monitor the deformation of the existing tunnel. If the deformation of the existing tunnel is stable after each section of load is removed, continue to remove the next section of heavy objects until all of them are removed. If the deformation is unstable, continue grouting or take measures. Other stratum reinforcement measures will not affect the subsequent deformation of the tunnel until the load is removed; after the deformation of the tunnel is stable, the pipe jacking machine will be disassembled and lifted out of the receiving shaft and follow-up work.

The beneficial effects of the present invention are specifically as follows:

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

2. According to the unloading balance method, the pipe joints are piled up 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;

3. The construction method is simple, the operation is convenient, the construction efficiency is high, and the cost is low.

Description of drawings

Fig. 1 is the flow chart of the unloading and balancing construction method of the newly-built pipe jacking on the existing subway tunnel in the embodiment of the present invention;

Fig. 2 is the arrangement diagram of the existing shield tunnel section deformation monitoring points in the embodiment of the present invention;

Fig. 3 is the calculation model of the scope of influence of newly-built pipe jacking excavation in the embodiment of the present invention;

Fig. 4 is the main influence area of new pipe jacking excavation in the embodiment of the present invention.

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings and embodiments.

The invention relates to a newly-built pipe jacking construction method for unloading balance of an existing subway tunnel, which includes arranging deformation monitoring points of the existing tunnel, calculating the influence range of excavation, entering the hole with a pipe jacking machine, and hoisting pads and pipe joints , pipe jacking and measurement, pressure injection of soil consolidation grout, existing tunnel deformation monitoring, judgment of maximum uplift value of tunnel, heap load pressure, pipe jacking machine out of the hole. The flow chart of the whole method is shown in Figure 1, which specifically includes the following steps:

Step 1. Arranging deformation monitoring points for existing tunnels

Arrange deformation monitoring points for existing subway tunnels 1 to 2 months before the official construction of pipe jacking. The sides are arranged according to 5m, 10m, and 20m, and 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 tunnel clearance convergence, and prism D is used to monitor the horizontal displacement of the ballast bed , the prism E is used to monitor the vertical displacement of the ballast bed, and the layout of the deformation monitoring points of the tunnel section is shown in Figure 2.

Step 2. Calculate the scope of excavation influence

The impact of rectangular pipe jacking construction on the existing tunnel changes dynamically with the excavation distance. Before the pipe jacking excavation, the influence range of the excavation is calculated by combining engineering data and theoretical methods, and the existing tunnel is regarded as resting on the Pasternak foundation. Based on the Timoshenko beam model above, the calculation model of the excavation influence range is shown in Figure 3. Using the Mindlin solution and the finite difference method to calculate the change diagram of the maximum uplift value of the existing tunnel with the excavation distance, the interval with no significant change in the uplift value is designated as the secondary impact area, and the interval with significant changes is designated as the main influence area. Detailed For the 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 shield tunnel toovercrossing tunneling in soft ground. Environmental Earth Sciences.80(5) ,1-15. Theoretical and a large number of actual measurement results show that the excavation surface is within 3 times the width of the newly-built pipe jacking from the existing tunnel axis as the main impact area, and outside the range of 3 times the width of the newly-built pipe jacking is the secondary impact area. The main impact area of the new tunnel excavation is shown in the figure 4.

Step 3, the pipe jacking machine enters the hole

After completing the measurement and setting out, 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.

Step 4. Hanging pads and pipe joints

After a pipe joint is jacked in by the pipe jacking jack, the block and pipe joint shall be hoisted in time, and a new pipe joint shall be installed.

Step five, pipe jacking and measurement

The pipe jacking speed v is controlled at 3.5-4m/d in the secondary influence area calculated in step 2, and is controlled at 2-3m/d in the main influence area. The jacking force F is combined with the engineering situation according to the formula (1) The rest of the construction parameters need to be dynamically adjusted according to the feedback data of the surface and tunnel deformation to achieve the best state.

During the jacking process, the jacking axis is closely controlled. After the jacking of each pipe section, the attitude of the machine head is measured. Once the machine head has a small rotation angle, measures such as cutter head reversal and iron pressing are immediately corrected. The pipe jacking machine is unearthed in the form of screw conveyor + track soil box + hoist + crawler crane. During the jacking process, the unearthed volume of each section should be counted as accurately as possible to keep it consistent with the theoretical unearthed volume, avoid over-excavation or under-excavation, ensure the relative stability of the front soil, and reduce disturbance to the stratum. During the pipe jacking process, the total station behind the launch shaft closely monitors the jacking distance of the pipe jacking, records the jacking distance and compares it with the scope of influence of the excavation. As the pipe jacking continues to be excavated, the jacking distance is gradually increased. The frequency of distance monitoring is 1-2 measurements a day in the secondary impact area, and 3-4 measurements a day in the main impact area, so as to timely judge the impact area where the pipe jacking excavation face is located.

Step 6. Pressure injection of soil consolidation slurry

During pipe jacking, the consolidation grout is injected in time through the grouting holes on the pipe wall, so that the grout penetrates into the soil layer around the pipe jacking and hardens in the soil layer, thereby achieving the effect of strengthening the soil layer. Squeeze of grouting: ground slurry mixing→start grouting pump→open main pipe valve→open pipe joint valve→slurry delivery→close pipe joint valve→main pipe valve close→disassemble quick joint in well→lower pipe joint→connect 2-inch main pipe→circulate start again. Grouting material and ratio: P042.5 cement is used as the cementitious material. A suitable grout ratio can not only improve the diffusion and reinforcement range of the grout, but also control the gelling time of the grout. The grout ratio should be controlled within the following range: 0.5: 1～1:1.

Step 7. Deformation monitoring of existing tunnels

During the pipe jacking process, an intelligent total station is used to monitor the deformation of the existing shield tunnel; when the pipe jacking excavation surface is in the secondary impact area, the monitoring frequency is 1-2 times/day. When the pipe excavation surface is in the main affected area, the monitoring frequency is 3-4 times/day.

Step 8. Determine the maximum uplift value of the tunnel

Before the excavation surface enters the main affected area, if the maximum vertical displacement value of the existing tunnel vault obtained by monitoring is less than the set early warning value, the setting range of the early warning value is 3-5 mm (in the embodiment, the early warning value is set to 3mm), there is no need to take ballasting measures for the pipe joints, and whether to take ballasting measures will be decided according to whether the maximum vertical displacement value of the existing tunnel vault that is monitored during the pipe jacking excavation process is greater than or equal to the set early warning value. If ballasting measures are not required, repeat steps 4 to 7 until the pipe jacking machine goes out of the hole in step 10.

Step 9. Heap load

When the pipe jacking excavation surface enters the main impact area or during the subsequent excavation process, if the monitored maximum vertical displacement value of the existing tunnel arch is greater than or equal to the set early warning value, the pipe joint needs to be ballasted measure. If stacking is carried out before the pipe jacking excavation surface enters the main impact area, the weight difference between the excavated soil and pipe joints will be calculated in time after the pipe jacking machine excavates the soil in front of the tunnel to the capacity of one pipe joint each time. , Use prefabricated C20 plain concrete or iron blocks with the same weight difference to carry out stacking and ballasting on the pipe joints in the main influence area. In order to facilitate later transportation, nine splints are used to divide the plain concrete into layers and blocks. Pulley traffic. Subsequent excavation of the soil can only be carried out after the excavation of the soil of each pipe joint until the heap load is completed. When the ballasted pipe joints leave the main influence area, the plain concrete or iron blocks used for ballasting shall be moved to the pipe joints that subsequently enter the main influence area. If stacking is implemented during subsequent excavation, all pipe joints in the main impact area should be stacked immediately, and the steps are the same as above.

Step 10, the pipe jacking machine exits the hole

If ballasting measures are not taken during the whole process of pipe jacking, the pipe jacking machine shall be disassembled and hoisted out of the receiving well, followed by grout replacement, removal of equipment in the pipe, caulking, cleaning, and joint treatment.

Step 11. Soil reinforcement in the main affected area

If ballasting measures are taken for the pipe jacking, the soil layer in the main affected area shall be grouted and reinforced through the grouting holes of the pipe joints after the pipe jacking is fully penetrated.

Step 12. Remove the load

After grouting reinforcement, the loads are removed section by section, and the deformation of the existing tunnel is monitored synchronously. If the deformation of the existing tunnel is stable after each section of the load is removed, continue to remove the next section of the load until all the loads are removed. If the deformation is unstable, continue grouting or take other ground reinforcement measures until the removal of heavy objects will not affect the subsequent deformation of the tunnel. After the tunnel deformation is stable, proceed to the follow-up work after the pipe jacking machine is hoisted out of the receiving shaft in step ten.

The above descriptions are only preferred implementations of the present invention, and the protection scope of the present invention is not limited to the above-mentioned embodiments, and all technical solutions under the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those skilled in the art, some improvements and modifications without departing from the principles of the present invention should also be regarded as the protection scope of the present invention.

Claims (10)

1. a kind of newly-built rectangular pipe jacking wears existing subway tunnel unloading balance construction method, it is characterized in that, comprises the following steps: S1. Arrange deformation monitoring points of existing tunnels; S2. Calculate the scope of impact of excavation, regard the existing tunnel as a Timoshenko beam model placed on the Pasternak foundation, and obtain the main scope of the longitudinal deformation of the existing tunnel affected by the new pipe-jacking tunnel; S3. Measurement and setting out, installation of the pipe jacking machine frame, backrest, and main jacking device, equipment debugging, and the pipe jacking machine entering the hole; S4, hoisting pads and pipe joints; S5. Pipe jacking and measurement; S6. Pressure injection of soil consolidation grout, during pipe jacking, pressure injection of consolidation grout through the pipe wall grouting hole in time, so that the grout penetrates into the soil layer around the pipe jacking 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 surface enters the main affected area, if the monitored maximum vertical displacement value of the existing tunnel vault is less than the set early warning value, no ballasting measures will be taken for the pipe joints. Follow-up According to whether the maximum vertical displacement value of the existing tunnel vault that is monitored during the pipe jacking process is greater than or equal to the set early warning value, it is decided whether to take ballast measures; if no ballast measures are taken, repeat steps S4 to S7 until step S10 pipe jacking machine out of the hole; S9. Heap load and ballast. When the excavation face enters the main affected area or during the subsequent excavation process, if the monitored maximum vertical displacement value of the existing tunnel vault is greater than or equal to the set early warning value, the tunnel take ballast measures; S10. When the machine head arrives at the receiving shaft, the pipe jacking machine goes out of the hole. 2. The construction method according to claim 1, wherein the unloading and balancing construction method of the newly-built rectangular pipe jacking through the existing subway tunnel is characterized in that, the step S1 is specifically as follows: 1 to 2 months before the formal construction of the pipe jacking, the existing subway tunnel Deformation monitoring points are arranged in the subway tunnel. The layout range of the existing subway tunnel deformation monitoring section is 60m from the left and right sides of the plane intersection of the new and old tunnels. Five prisms are arranged, among which, the first prism is arranged at the top of the center of the section 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 respectively arranged on the ballast bed to monitor the horizontal displacement and the vertical displacement of the ballast bed respectively. 3. The newly-built rectangular pipe jacking method according to claim 1, wherein the unloading balance construction method of the existing subway tunnel is characterized in that, the step S2 is specifically: using the Mindlin solution and the finite difference method to calculate the maximum uplift value of the existing tunnel As shown in the diagram of changes with excavation distance, the interval with no significant change in uplift value is defined as the secondary impact area, and the interval with significant change is defined as the main impact area, specifically: the distance between the excavation face and the axis of the existing tunnel is 3 times the newly-built pipe jacking The main impact area is within the width range, and the secondary impact area is outside the range of 3 times the width of the newly-built pipe jacking. 4. The newly-built rectangular pipe jacking method according to claim 1, wherein the unloading and balancing construction method of the existing subway tunnel is characterized in that, in the step S3, the pipe jacking machine enters the hole specifically as follows: the measurement and lofting are to be completed, and the pipe jacking is installed Machine frame, backrest, main jacking device, equipment debugging, operating the pipe jacking machine to enter the hole after the broken hole door is working; hoisting pads and pipe joints are as follows: after a pipe jack is jacked into a pipe joint, hoist it in time Place spacers and joints, and install new joints. 5. The newly-built rectangular pipe jacking method according to claim 1, wherein the unloading balance construction method of the existing subway tunnel is characterized in that, the jacking and measurement of the pipe jacking in the step S5 are specifically: The pipe jacking speed v is controlled at 3.5-4m/d in the secondary influence area calculated in step 2, and is controlled at 2-3m/d in the main influence area. The jacking force F is combined with the engineering situation according to the formula (1) calculation, and the remaining construction parameters need to be dynamically adjusted according to the feedback data of the surface and tunnel deformation to achieve the best state: F＝F ₁ +F ₂ (1) In the formula: F is the minimum jacking force, the unit is kN; F ₁ is the frictional resistance between the pipeline and the soil layer, the unit is kN, F ₁ = (a+b)×2Lf, L is the pipe jacking length, the unit is m; f is The average frictional resistance between the outer wall of the pipeline and the soil, in kN/m ² , should be 7~12kN/m ² ; F ₂ is the head-on resistance of the pipe jacking machine, in kN, F ₂ =a×bR ₁ , R ₁ is the pipe jacking Passive earth pressure at the lower 1/3 of the 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. 6. The newly-built rectangular pipe jacking method according to claim 1, wherein the unloading and balancing construction method of the existing subway tunnel is characterized in that the grouting sequence of the pressure-injected soil consolidation grout in the step S6 is specifically: the ground Slurry mixing→start grouting pump→open main pipe valve→open pipe joint valve→slurry delivery→close pipe joint valve→main pipe valve close→disassemble quick joint in well→lower pipe joint→connect 2-inch main pipe→cycle start again; grouting Materials and ratio: P042.5 cement is used as the cementitious material, and the ratio of slurry is controlled within the following range: 0.5:1～1:1. 7. The newly-built rectangular pipe jacking method according to claim 1, wherein the unloading and balancing construction method of the existing subway tunnel is characterized in that, the deformation monitoring of the existing tunnel in the step S7 is specifically: during the pipe jacking process, the The deformation of the existing shield tunnel is monitored with an intelligent total station; when the pipe jacking excavation surface is in the secondary influence area, the monitoring frequency is 1-2 times/day; when the pipe jacking excavation surface is in the main influence area , The monitoring frequency is 3-4 times/day. 8. The construction method for unloading and balancing construction of a new rectangular pipe jacking on an existing subway tunnel according to claim 1, characterized in that the setting range of the warning value in the steps S8 and S9 is 3-5 mm. 9. The newly-built rectangular pipe jacking method according to claim 1, wherein the existing subway tunnel unloading balance construction method is characterized in that, in the step S9, the specific steps of taking ballast measures for the pipe joints are: S91. If stacking and ballasting is carried out before the excavation surface of the pipe jacking enters the main affected area, after the pipe jacking machine excavates the capacity of a pipe joint in the soil in front of the tunnel each time, the excavated soil and pipe joints will be calculated in time. If the weight difference of the joints is different, the prefabricated C20 plain concrete or iron blocks with the same weight difference shall be used to carry out heap ballasting on the pipe joints in the main influence area; after the excavation of the soil body of each pipe joint until the heap ballasting is completed, When the ballasted pipe joint leaves the main impact area, the plain concrete or iron block used for ballasting is moved to the subsequent pipe joint that enters the main impact area; S92. If heaping is to be carried out during the subsequent excavation process, immediately perform heaping and ballasting on all pipe joints in the main influence area, and the specific steps are consistent with the above-mentioned step S91. 10. The newly-built rectangular pipe jacking method according to claim 1, wherein the unloading and balancing construction method of passing through an existing subway tunnel is characterized in that, the exiting hole of the pipe jacking machine in the step S10 specifically includes two situations: S101. If ballasting measures are not taken during the whole process of pipe jacking, the pipe jacking machine shall be disassembled and hoisted out of the receiving well, followed by grout replacement, removal of equipment in the pipe, caulking, cleaning, and joint treatment; S102. If ballasting measures are taken for the pipe jacking, after the pipe jacking is completely penetrated, the soil layer in the main affected area shall be grouted and reinforced through the grouting holes of the pipe joints; Simultaneously monitor the deformation of the existing tunnel. If the deformation of the existing tunnel is stable after each section of load is removed, continue to remove the next section of heavy objects until all are removed. If the deformation is unstable, continue grouting or take measures Other stratum reinforcement measures will not affect the subsequent deformation of the tunnel until the load is removed; after the deformation of the tunnel is stable, the pipe jacking machine will be disassembled and hoisted out of the receiving shaft and follow-up work.

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