Construction method for shallow-buried small clear-distance double-row pipe jacking of water-rich sand layer spanning over subway

Abstract

The invention discloses a construction method for shallow-buried small clear-distance double-row pipe jacking in water-rich sand layer straddling a subway. First, determine the pre-construction position of the right pipeline, and use a pipe jacking machine for pre-construction. Inject thixotropic slurry for reinforcement while jacking, adjust and determine the parameters for formal construction. After the formal construction is completed, replace the thixotropic slurry with cement mortar. Secondly, determine the pre-construction position of the left pipeline. Inject thixotropic slurry for reinforcement of the soil around the left pipeline while jacking the left pipeline. At the same time, inject cement mortar into the middle sandy soil in the right pipeline to reinforce it. After determining the parameters of the left pipeline, carry out formal construction. During the formal construction, after adjusting and determining the actual reinforcement amount of the cement mortar in the middle sandy soil, carry out reinforcement while jacking. After the formal construction is completed, replace the thixotropic slurry with cement mortar. The method of the invention solves the problem that when constructing another pipeline under the condition that one pipeline construction of the small clear-distance double-row pipe is completed, it is easy to cause the collapse between the double-row pipes or the damage of the completed pipeline, and ensures the safety and reliability of the construction.

Description

Technical Field

[0001] The invention belongs to the technical field of pipe jacking construction in water-rich sand layers, and particularly relates to a construction method for shallow-buried small clear-distance double-row pipe jacking in water-rich sand layers spanning over a subway. Background Art

[0002] With the rapid development of society, the continuous expansion of the rail transit network brings a large number of problems of pipeline crossing construction. Especially in the geological conditions of water-rich sand layers, due to the soft soil layer with very high water content, poor mechanical properties and strong water permeability, it is very unfavorable for pipe jacking construction. During operation, the tunnel will inevitably float due to the unloading of the upper soil body. If the deformation is too large, it will affect its normal operation; for the existing roads on the ground, there is no foundation below due to its jacking process, and the pipe jacking undercrossing process may cause settlement. When constructing the other pipe in the case of completing the construction of one of the small clear-distance double-row pipes, it is easy to cause the collapse of the water-rich sandy soil between the double-row pipes or the damage of the completed pipe.

[0003] Patent document CN112983456A discloses a method for controlling surface deformation of multi-row pipe jacking in water-rich sand layers. The protected claim is "a method for controlling surface deformation of multi-row pipe jacking in water-rich sand layers, characterized by including the steps: S1, construction preparation; S2, collecting geological data; S3, leveling the site and measuring and setting out; S4, drilling and selecting casing pipes; S5, arranging surface monitoring points; S6, jacking until the receiving well; in step S6, before jacking, ground drilling and grouting reinforcement are adopted, and during jacking, the resistance is reduced through a drag reduction mud system, the jacking force and the soil chamber pressure are controlled to reduce surface deformation, and the surface deformation construction monitoring of multi-row pipe jacking is carried out.", and its control method monitors data in real time throughout the process and does not involve how to reinforce the water-rich sand layer between multi-row pipe jacking. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a construction method for shallow-buried small clear-distance double-row pipe jacking in water-rich sand layers spanning over a subway, so as to solve the problem of no specific method for reinforcing the water-rich sand layer between multi-row pipes in the prior art, and at the same time, it does not require real-time monitoring throughout the process.

[0005] To achieve the above purpose, the present invention provides the following technical solution, which is to provide a construction method for shallow-buried small clear-distance double-row pipe jacking in water-rich sand layers spanning over a subway, including the following steps:

[0006] S1, determining the pre-construction position of the right pipeline according to the actual position of the right pipeline in the water-rich sand layer;

[0007] S2, using a pipe jacking machine to carry out pre-construction at the pre-construction position of the right pipeline, injecting thixotropic mud while jacking the right pipeline to reinforce the soil around the right pipeline, and adjusting the jacking pressure and grouting pressure of the right pipeline;

[0008] S3. After determining the jacking pressure and grouting pressure of the right pipeline, the jacking construction of the right pipeline is officially carried out;

[0009] S4. After completing the jacking construction of the right pipeline, the thixotropic slurry is replaced with cement mortar;

[0010] S5. Determine the pre-construction position of the left pipeline according to the actual position of the left pipeline in the water-rich sand layer;

[0011] S6. Use the pipe jacking machine to carry out pre-construction at the pre-construction position of the left pipeline. During the jacking of the left pipeline, thixotropic slurry is injected to reinforce the soil around the left pipeline, and the jacking pressure and grouting pressure of the left pipeline are adjusted. At the same time, cement mortar is injected through the right pipeline to reinforce the sand in the middle of the double pipelines;

[0012] S7. After determining the jacking pressure and grouting pressure of the left pipeline, the jacking construction of the left pipeline is officially carried out;

[0013] S8. During the jacking construction of the left pipeline, adjust the actual reinforcement amount of the cement mortar for the sand in the middle of the double pipelines through the right pipeline. After determining the actual reinforcement amount of the cement mortar for the sand in the middle, carry out jacking while reinforcing;

[0014] S9. After completing the jacking construction of the left pipeline, the thixotropic slurry is replaced with cement mortar;

[0015] Among them, the distance between the left pipeline and the right pipeline is 1.16 m, and the buried depth from the existing road is 5.8 m.

[0016] Preferably, in step S1, a 15-m test section is set for pre-construction on the jacking of the right pipeline across the subway.

[0017] Preferably, in step S2, the diameter of the pipe jacking machine is 4 m.

[0018] Preferably, in step S2, the grouting volume V′ per meter needs to be calculated, and it is calculated according to the following formula: V′ = π(R + d) 2 , where R is the radius of the pipeline and d is the thickness of a layer of slurry sleeve formed by injecting thixotropic slurry on the side wall of the pipe during jacking construction.

[0019] Preferably, when the actual soil output volume V per meter is less than or equal to the grouting volume V′ per meter, the jacking pressure and grouting pressure are the jacking pressure and grouting pressure for the official construction. Otherwise, the jacking pressure and grouting pressure in the pre-construction stage need to be adjusted to meet the above requirements.

[0020] Preferably, in step S5, a 15-m test section is set for pre-construction on the jacking of the left pipeline across the subway.

[0021] Preferably, in step S8, the theoretical reinforcement amount V′1 of the cement mortar for the sand in the middle of the double pipelines needs to be calculated, and it is calculated according to the following formula: V′1 = ωV 砂 , where ω is the water content of the reinforcement area and V砂 The volume of water-rich sandy soil in the reinforcement area.

[0022] Preferably, when the actual reinforcement volume V1 of the sandy soil cement mortar in the middle of the double-row pipes is less than the theoretical reinforcement volume V'1 of the sandy soil cement mortar in the middle of the double-row pipes, it is necessary to increase the actual reinforcement volume V1 of the sandy soil cement mortar in the middle of the double-row pipes to be greater than or equal to the theoretical reinforcement volume V'1 of the sandy soil cement mortar in the middle of the double-row pipes to meet the above requirements.

[0023] Preferably, the construction of step S8 must be carried out before the setting of the cement mortar in step S4.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) For the construction method of the double-row pipe jacking with a shallow buried small clear distance in the water-rich sand layer crossing the subway used in the present invention, a pre-construction section is set in front of the actual positions of the right pipeline and the left pipeline, the grouting volume V' per meter is calculated, and compared with the actual soil output volume V per meter in the pre-construction stage, the jacking pressure and the grouting pressure of the thixotropic slurry in the formal construction stage are comprehensively obtained, solving the problem of real-time monitoring and saving time and cost.

[0026] (2) For the construction method of the double-row pipe jacking with a shallow buried small clear distance in the water-rich sand layer crossing the subway used in the present invention, the distance between the left pipeline and the right pipeline is 1.16 m, and the buried depth from the existing road is 5.8 m, with a very high space utilization rate. During the pipe jacking construction process, the greater the buried depth from the existing road, the greater the construction difficulty. The present invention reduces the construction difficulty.

[0027] (3) For the construction method of the double-row pipe jacking with a shallow buried small clear distance in the water-rich sand layer crossing the subway used in the present invention, during the pre-construction and formal construction of the left pipeline, while injecting thixotropic slurry into the left pipeline, cement slurry is continuously injected into the right pipeline, strengthening the middle sandy soil between the double-row pipes, solving the problem that when constructing another pipeline under the condition that one of the double-row pipes is completed, it is easy to cause the collapse of the water-rich sandy soil between the double-row pipes or the damage of the completed pipeline. Brief Description of the Drawings

[0028] Figure 1 is the construction process flow chart of the present invention;

[0029] Figure 2 is the construction schematic diagram of the right pipeline jacking of the present invention;

[0030] Figure 3 is the schematic diagram before the pre-construction of the left pipeline after the construction of the right pipeline jacking of the present invention;

[0031] Figure 4 is the construction schematic diagram of the left pipeline jacking of the present invention;

[0032] Figure 5This is a schematic diagram after the jacking construction of the left pipeline of the present invention is completed.

[0033] In the figure: 1. Road; 2. Subway; 3. Water-rich sand layer; 4. Right pipeline; 5. Thixotropic slurry; 6. Cement mortar; 7. Left pipeline. Specific implementation manners

[0034] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0035] Embodiment 1

[0036] Refer to the attached Figures 1 to 5 , a construction method for a shallow-buried small clear distance double-row pipe jacking in a water-rich sand layer spanning over a subway provided by the present invention includes the following steps:

[0037] S1) Since most of the geological features between the existing road 1 and the existing subway 2 are water-rich sand layer 3, a 15m test section is set for pre-construction of the right pipeline 4 by pipe jacking spanning over the subway 2 according to the actual position of the right pipeline 4;

[0038] S2) Select a pipe jacking machine with a diameter of 4m to perform pre-construction at the pre-construction position of the right pipeline 4. Thixotropic slurry 5 is injected while the right pipeline 4 is being jacked to reinforce the soil around the right pipeline 4. Calculate the grouting volume V' per meter of the right pipeline 4, that is, V' = π(R + d) 2 , where R is the radius of the pipeline, and d is the thickness of a layer of slurry sleeve formed by injecting thixotropic slurry on the side wall of the pipe jacking during the jacking construction. In the present invention, the diameter of the pipe jacking machine is 4m, the diameter of the right pipeline is between 4.5 - 4.8m, and the thickness of the slurry sleeve is taken as 0.03m. Compare the grouting volume V' per meter of the right pipeline 4 with the actual soil output volume V per meter of the right pipeline 4. When V is greater than V', adjust the jacking pressure and grouting pressure of the right pipeline 4 until V is less than or equal to V';

[0039] S3) After taking the jacking pressure and grouting pressure of the right pipeline 4 when V is less than or equal to V' as the jacking pressure and grouting pressure for the formal construction of the right pipeline 4, formally perform the jacking construction of the right pipeline 4. Thixotropic slurry 5 is injected while the right pipeline 4 is being jacked to reinforce the soil around the right pipeline 4;

[0040] S4) After completing the jacking construction of the right pipeline 4, replace the thixotropic slurry 5 with cement mortar 6 around the right pipeline 4;

[0041] S5) Set a 15m test section for pre-construction of the left pipeline 7 by pipe jacking spanning over the subway 2 according to the actual position of the left pipeline 7;

[0042] S6) Select a pipe jacking machine with a diameter of 4 m to perform pre-construction at the pre-construction position of the left pipeline 7. While jacking the left pipeline 7, inject thixotropic slurry 5 to reinforce the soil around the left pipeline 7. At the same time, inject cement mortar 6 through the right pipeline 4 to reinforce the sandy soil in the middle of the double pipes. Calculate the grouting volume V' per meter of the left pipeline 7 according to the method in S2 above. Compare the grouting volume V' per meter of the left pipeline 7 with the actual soil output volume V per meter of the left pipeline 7. When V is greater than V', adjust the jacking pressure and grouting pressure of the left pipeline 7 until V is less than or equal to V';

[0043] S7) After taking the jacking pressure and grouting pressure of the left pipeline 7 when V is less than or equal to V' as the jacking pressure and grouting pressure for the formal construction of the left pipeline 7, formally carry out the jacking construction of the left pipeline 7;

[0044] S8) During the jacking construction of the left pipeline 7, calculate the theoretical reinforcement volume V'1 of the cement mortar 6 in the sandy soil in the middle of the double pipes, that is, V'1 = ωV 砂 , where ω is the water content of the reinforcement area and V 砂 is the volume of water-rich sandy soil in the reinforcement area. Compare the theoretical reinforcement volume V'1 of the cement mortar 6 in the sandy soil in the middle of the double pipes with the actual reinforcement volume V1 of the cement mortar 6 in the sandy soil in the middle of the double pipes. When the actual reinforcement volume V1 of the cement mortar 6 in the sandy soil in the middle of the double pipes is less than the theoretical reinforcement volume V'1 of the cement mortar 6 in the sandy soil in the middle of the double pipes, increase the actual reinforcement volume V1 of the cement mortar 6 in the sandy soil in the middle of the double pipes until it is greater than or equal to the theoretical reinforcement volume V'1. The right pipeline 4 uses the actual reinforcement volume V1 of the cement mortar 6 in the sandy soil in the middle of the double pipes that is greater than or equal to the theoretical reinforcement volume V'1 of the cement mortar 6 in the sandy soil in the middle of the double pipes to reinforce the sandy soil in the middle of the double pipes. At the same time, inject thixotropic slurry 5 while jacking the left pipeline 7 to reinforce the soil around the left pipeline 7. Since the cement mortar 6 in this step is injected through the right pipeline 4, this step must be carried out before the cement mortar 6 replaced in step S4 solidifies;

[0045] S9) After completing the jacking construction of the left pipeline 7, replace the thixotropic slurry 5 with cement mortar 6 around the left pipeline 7.

[0046] During the process of injecting cement mortar 6 through the right pipeline 4 to reinforce the sandy soil in the middle of the double pipes, due to the different compositions of the water-rich sand layers 3 in each section, the distribution form of the cement mortar in the sandy soil in the middle of the double pipes may be as Figure 4 shown, or may be as Figure 5 shown or in a state between Figure 4 and Figure 5 ;

[0047] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A construction method for a double-row pipe jacking with shallow burial and small clear distance in water-rich sand layer spanning over a subway, characterized in that, It includes the following steps: S1. Determine the pre-construction position of the right pipeline (4) based on the actual position of the right pipeline (4) in the water-rich sand layer (3). S2. Use a pipe jacking machine to carry out pre-construction at the pre-construction position of the right pipeline (4). While jacking the right pipeline (4), inject thixotropic slurry (5) to reinforce the soil around the right pipeline (4), and adjust the jacking pressure and grouting pressure of the right pipeline (4). S3. After determining the jacking pressure and grouting pressure of the right pipeline (4), formally carry out the jacking construction of the right pipeline (4). S4. After completing the jacking construction of the right pipeline (4), replace the thixotropic slurry (5) with cement mortar (6). S5. Determine the pre-construction position of the left pipeline (7) based on the actual position of the left pipeline (7) in the water-rich sand layer (3). S6. Use a pipe jacking machine to carry out pre-construction at the pre-construction position of the left pipeline (7). While jacking the left pipeline (7), inject thixotropic slurry (5) to reinforce the soil around the left pipeline (7), adjust the jacking pressure and grouting pressure of the left pipeline (7), and at the same time inject cement mortar (6) through the right pipeline (4) to reinforce the sand in the middle of the double pipes. S7. After determining the jacking pressure and grouting pressure of the left pipeline (7), formally carry out the jacking construction of the left pipeline (7). S8. During the jacking construction of the left pipeline (7), adjust the actual reinforcement amount of the cement mortar (6) for the sand in the middle of the double pipes through the right pipeline (4). After determining the actual reinforcement amount of the cement mortar (6) for the sand in the middle, carry out jacking while reinforcing. S9. After completing the jacking construction of the left pipeline (7), replace the thixotropic slurry (5) with cement mortar (6). Among them, the distance between the left pipeline (7) and the right pipeline (4) is 1.16 m, and the buried depth from the existing road is 5.8 m.

2. The construction method of the shallow-buried small clear distance double-row pipe jacking in the water-rich sand layer straddling the subway according to claim 1, characterized in that, In step S1, a 15-m test section is set for pre-construction by jacking the pipe of the right pipeline (4) over the subway (2).

3. The construction method of the shallow-buried small clear distance double-row pipe jacking in the water-rich sand layer straddling the subway according to claim 1, characterized in that, In step S2, the diameter of the pipe jacking machine is 4 m.

4. The construction method of the shallow-buried small clear-distance double-row pipe jacking in water-rich sand layer spanning over the subway according to claim 1, characterized in that, In step S2, it is necessary to calculate the grouting volume V' per meter, which is calculated according to the following formula: V' = π(R + d) 2 , where R is the radius of the pipeline, and d is the thickness of a layer of slurry jacket formed on the side wall of the pipe jacking during the pipe jacking construction by injecting thixotropic slurry.

5. The construction method of the double-row pipe jacking with shallow burial and small clear distance in the water-rich sand layer straddling the subway according to claim 4, characterized in that, The jacking pressure and grouting pressure when the actual soil output volume V per meter is less than or equal to the grouting volume V' per meter are the jacking pressure and grouting pressure for formal construction. Otherwise, it is necessary to adjust the jacking pressure and grouting pressure in the pre-construction stage to meet the above requirements.

6. The construction method of the double-row pipe jacking with shallow burial and small clear distance in water-rich sand layer straddling the subway according to claim 1, characterized in that, In step S5, a 15-m test section is set for pre-construction by jacking the pipe of the left pipeline (7) over the subway (2).

7. The construction method of the shallow-buried small clear-distance double-row pipe jacking in the water-rich sand layer spanning over the subway according to claim 1, characterized in that, In step S8, it is necessary to calculate the theoretical reinforcement volume V1' of the sandy soil cement mortar (6) in the middle of the double-row pipes, which is calculated according to the following formula: V1' = ωV 砂 , where ω is the water content of the reinforcement area, and V 砂 is the volume of water-rich sandy soil in the reinforcement area.

8. The construction method of the double-row pipe jacking with shallow burial and small clear distance in water-rich sand layer straddling the subway according to claim 7, characterized in that, When the actual reinforcement amount V1 of the cement mortar (6) for the sand in the middle of the double pipes is less than the theoretical reinforcement amount V1' of the cement mortar (6) for the sand in the middle of the double pipes, it is necessary to increase the actual reinforcement amount V1 of the cement mortar (6) for the sand in the middle of the double pipes to be greater than or equal to the theoretical reinforcement amount V1' of the cement mortar (6) for the sand in the middle of the double pipes to meet the above requirements.

9. The construction method of the shallow-buried small clear-distance double-row pipe jacking in water-rich sand layer spanning over the subway according to claim 1, characterized in that, The construction of step S8 must be carried out before the cement mortar (6) in step S4 solidifies.

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