A construction method for dealing with underground obstacle pipelines during the trench excavation of diaphragm walls

Abstract

The present invention provides a construction method for dealing with underground obstacle pipelines during the trench excavation of diaphragm walls. Construction workers enter from the inspection shaft, insert an engineering airbag into the underground obstacle pipeline, and its installation position is 500 mm before and after the diaphragm wall trench section. The underground obstacle pipeline is successively inflated and pressurized for plugging. Then, a guide wall is constructed from the ground, and a trench cutter is used to excavate the trench, and the pipeline structure within the trench section is broken. After that, the trench is brushed and bottom cleared, and channel steel is inserted through the reinforcement cage and fixed on the guide wall. Concrete is poured into the trench through a concrete pouring conduit. After the pouring is completed, the concrete pouring conduit is withdrawn, and the concrete solidifies to form a diaphragm wall. By using the engineering airbag, the loss of slurry for protecting the trench wall and the poured concrete can be effectively avoided, thereby reducing the risk of trench wall collapse and ensuring the construction safety of the trench section and the ground.

Description

Technical Field

[0001] The present invention relates to the technical field of underground construction engineering, and particularly relates to a construction method for dealing with underground obstacle pipelines during the trench excavation of a diaphragm wall. Background Art

[0002] With the development and construction of underground space, it is often affected by underground pipelines. After the pipelines are newly built and relocated out of the site area, the original pipelines still hinder the project implementation. Especially for pipelines with a diameter above DN600, treatment measures need to be taken. For open-cut foundation pit projects, the common practices for the diaphragm wall of the retaining structure to cross the obstacle pipelines are as follows: for pipelines with a relatively shallow burial depth, they are usually excavated and broken before the trench excavation of the diaphragm wall, and then backfilled; for projects with a relatively large burial depth and a too high cost for excavation treatment, a punching machine is directly used to break them during the trench excavation.

[0003] For the above construction method of excavation, breaking and then backfilling, its excavation operation has a greater impact on the surrounding environment, and the cost is relatively high. Excavation, backfilling and then trench excavation and removal will cause certain engineering waste, and the excavation treatment risk increases as the pipeline burial depth increases. For the method of directly punching and removing with a punching machine during the trench excavation, since the trench excavation of the retaining structure requires slurry support to ensure the safety and stability of the trench section, when the pipeline wall is damaged instantaneously for the underground interconnected pipelines, a large amount of slurry in the trench section may be lost, resulting in the collapse of the trench section; in addition, during the underwater concrete pouring of the diaphragm wall of the retaining structure, a large amount of cement slurry may flow out along the pipeline, causing waste and also increasing the project cost.

[0004] After retrieval, the publication number CN105672251A discloses a construction method for a diaphragm wall trench section straddling an existing sewage pipe. This patent erects pipeline protection devices on both sides of the sewage pipe to play a role in protecting the sewage pipe during the trench excavation process; for the relocation and new construction of pipelines, it cannot better provide construction conditions, and if the method of straddling the underground obstacle pipeline is used for construction, the construction cost will increase significantly compared with the technology of the present invention. Summary of the Invention

[0005] To solve the above technical problems, the present invention provides a construction method for dealing with underground obstacle pipelines during the trench excavation of a diaphragm wall. The specific technical solution is as follows:

[0006] A construction method for dealing with underground obstacle pipelines during the trench excavation of a diaphragm wall includes the following steps:

[0007] Step S1: Conduct construction survey and locate the sidelines on both sides of the diaphragm wall surface, lay out the excavation range of the guide wall by setting out, and conduct trench excavation until the bottom elevation of the guide wall is reached. Then, bind the steel bars of the guide wall and erect the formwork of the guide wall, pour the concrete of the guide wall, and compact the back of the guide wall with clay layer by layer; after the concrete strength of the guide wall reaches 70% of the design strength, remove the formwork of the guide wall, and finally backfill and compact the clay.

[0008] Step S2: Locate the depth of the underground obstacle pipeline. Combine with the position of the diaphragm wall in Step S1 to determine the position of the engineering airbag. The operator enters the underground obstacle pipeline from the maintenance shaft, first installs and inflates the engineering airbag at the far end, then installs and inflates the engineering airbag at the near end, and checks for air leakage and air pressure value.

[0009] Step S3: Divide the site into groove section widths according to the design drawings, and use the grooving machine to excavate the groove section. During this period, the groove section is always filled with mud, and the mud specific gravity in the groove is controlled through the mud circulation system. When the hydraulic grab of the grooving machine is close to the underground obstacle pipeline, operate with a small feed rate. During the construction of the groove section, the mud should be replenished in a timely manner to always maintain the required liquid level height. First, locally damage the pipeline wall of the obstacle, replenish fresh mud in a timely manner according to the change of the mud, and at the same time check and pay attention to the situation in the maintenance shaft. If there is a mud leakage situation, pressurize the engineering airbag in a timely manner.

[0010] Step S4: After conducting quality inspection on the groove body, carry out the grooving cleaning work. Install a special wire brush for grooving cleaning on the hydraulic grab of the grooving machine to complete the cleaning of the side wall of the groove body.

[0011] Step S5: After the grooving cleaning work is completed, clean the sediment at the bottom of the groove body and complete the replacement of the mud in the groove body.

[0012] Step S6: Use 2 crawler cranes to cooperate with each other to make the steel cage perpendicular to the ground, hoist the steel cage to the designed height in the groove body, and fix the steel cage on the guide wall by inserting channel steel into the steel cage.

[0013] Step S7: Install the concrete pouring conduit along the side wall of the groove body, pour concrete into the groove body through the concrete pouring conduit, and draw out the concrete pouring conduit after the pouring is completed. The concrete solidifies to form the diaphragm wall.

[0014] Further, in the Step S1, the net distance between the two side guide walls should be greater than 40 - 60 mm of the designed size of the diaphragm wall; the allowable deviation of the parallelism between the inner wall surface of the guide wall and the longitudinal axis of the diaphragm wall is ±10 mm, the allowable deviation of the flatness of the top surface of the guide wall is 5 mm, the allowable deviation of the flatness of the inner wall surface is 3 mm, and the allowable deviation of the perpendicularity of the inner wall surface of the guide wall is 5‰.

[0015] Further, in the Step S3, the allowable deviation of the groove section length is ±2.0%; the allowable deviation of the groove section thickness is +1.5%, -1.0%; the allowable deviation of the groove section perpendicularity is ±1 / 300.

[0016] Further, in the Step S5, 1 hour after the completion of the groove bottom cleaning and mud replacement, the mud specific gravity within a height of 500 mm from the groove bottom is not greater than 1.15, and the sediment thickness is not greater than 100 mm.

[0017] Further, there is a 500 - mm gap between the lower end of the steel reinforcement cage and the bottom of the trench in step S6. There is a 100 - 150 - mm gap between the end parts on both sides of the steel reinforcement cage and the joint surface of the adjacent diaphragm walls. At the same time, positioning pads are welded on both sides of the steel reinforcement cage. There are two columns on each side in the horizontal direction of the steel reinforcement cage, and the longitudinal spacing of each positioning pad is 3 - 5 m, and 2 - 3 pads are arranged in each layer.

[0018] Further, the local protrusion of the diaphragm wall surface is not more than 100 mm; the deviation of the center line of the wall top is not more than 30 mm.

[0019] Further, in step S7, the horizontal layout distance of the concrete - pouring conduit is not more than 3 m, and the distance from the end of the trench section should not be more than 1.5 m. The height difference between the bottom surfaces of each conduit is not more than 0.3 m; the lower end of the conduit should be 300 - 500 mm away from the bottom of the trench.

[0020] Advantages of the present invention:

[0021] 1. Using the engineering airbag to block the obstacle pipeline can effectively avoid the loss of slurry for trench - wall protection and the poured concrete, thereby reducing the risk of trench - wall collapse, ensuring the safety of trench - section and ground construction, and reducing the impact on the environment.

[0022] 2. Compared with the traditional method of excavating and removing the obstacle pipeline and then backfilling in the open - cut foundation pit engineering, the present invention can greatly improve the construction speed, and at the same time reduce the cost of excavating the foundation pit project, with obvious economic efficiency. Brief Description of the Drawings

[0023] Figure 1 is a schematic cross - section view of the trench forming and pipeline breaking of the diaphragm wall in the embodiment of the present invention.

[0024] Figure 2 is a schematic cross - section view of the hoisting and pouring of the diaphragm wall in the embodiment of the present invention.

[0025] Figure 3 is a process flow chart of the embodiment of the present invention.

[0026] Figure 4 is a schematic diagram of the mud circulation in the embodiment of the present invention.

[0027] In the figures, 1. trench section; 2. underground obstacle pipeline; 3. engineering airbag; 4. maintenance shaft; 5. guide wall; 6. trench - forming machine; 7. hydraulic grab of the trench - forming machine; 8. wire brush; 9. sediment at the bottom of the trench; 10. steel reinforcement cage; 11. crawler crane; 12. concrete - pouring conduit; 13. mud circulation system. Detailed Embodiments

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to 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 skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus cannot be understood as a limitation to the present invention.

[0030] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "a plurality" means two or more, unless otherwise specifically defined.

[0031] In the present invention, unless otherwise clearly defined and limited, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it can be a connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements.

[0032] As Figures 1 to 4 shown, a construction method for treating underground obstacle pipelines during the trench excavation of diaphragm walls

[0033] Relevant preparatory work is carried out before implementation, including "three connections and one leveling", assembly of construction machinery, mud circulation system, steel bar work, etc.; the so-called "three connections and one leveling" refers to the abbreviation for the conditions that the construction site reaches water connection, power connection, road connection and site leveling, meeting the requirements of water supply, power supply and smooth access roads for construction; the site leveling means that by cutting high and filling low, the original ground is transformed into a site plane that meets the needs of construction personnel, etc., avoiding large ground undulations that are not conducive to the standing and stability of construction machinery. The mechanical assembly means that after the disassembled construction machinery components are transported into the construction site, they are assembled, such as the grooving machine 6, heavy crawler crane, etc., all of which need to be assembled on site. The mud circulation system is a publicly known system for mud preparation and circulation, as follows Figure 4 , including various sedimentation tanks, slurry storage tanks, mud preparation devices, circulation pipelines, etc. The steel bar work includes the material yard for making the steel reinforcement cage 10 of the diaphragm wall, the processing workshop for the steel reinforcement cage 10, and the construction of the steel reinforcement cage 10. The steel reinforcement cage 10 is the stress steel bar framework of the diaphragm wall, which is a publicly known and widely used mature technology. After being cast integrally with concrete, it forms a reinforced concrete member with greater stiffness.

[0034] Specifically, it includes the following steps:

[0035] Step S1: Measure and position the sidelines on both sides of the diaphragm wall. The diaphragm wall is a publicly known underground engineering support structure with good horizontal bearing capacity and water isolation effect, generally with a diameter of 300mm - 2000mm. Lay out the excavation range of the guide wall 5 and carry out trenching until the bottom elevation of the guide wall 5 is reached. Then, bind the steel bars of the guide wall 5 and erect the wooden formwork of the guide wall 5, and pour concrete. The guide wall 5 is a publicly known measure for implementing the diaphragm wall trench section to ensure the safety and stability of the trench section within a certain depth range of the ground surface. The back of the guide wall 5 is compacted with clay in layers to prevent the seepage of the grooving mud, ensuring the close contact between the wall surface of the guide wall 5 and the soil surface. The guide wall 5 should have good strength, stiffness and integrity to prevent collapse. After the concrete strength of the guide wall 5 reaches 70% of the design strength, remove the wooden formwork and related wooden supports of the guide wall 5, and finally backfill and compact the clay; the clear distance between the two side guide walls 5 should be greater than 40 - 60mm of the design size of the diaphragm wall; the allowable deviation of the parallelism between the inner wall surface of the guide wall 5 and the longitudinal axis of the diaphragm wall is ±10mm, the allowable deviation of the flatness of the top surface of the guide wall 5 is 5mm, the allowable deviation of the flatness of the inner wall surface is 3mm, and the allowable deviation of the perpendicularity of the inner wall surface of the guide wall 5 is 5‰;

[0036] Step S2: Locate the depth of the underground obstacle pipeline 2. Combine with the position of the diaphragm wall in Step S1 to determine the position of the engineering airbag 3, which is ensured to be at a position 500 mm before and after the diaphragm wall trench section. The operator enters the underground obstacle pipeline 2 from the maintenance shaft 4, first installs and inflates the engineering airbag 3 at the distal end, then installs and inflates the engineering airbag 3 at the proximal end, and checks for air leakage, air pressure value, etc., and retains relevant image data. The engineering airbag 3 is made of natural rubber, which is easy to carry before inflation. After being stuffed into the underground obstacle pipeline 2 and inflated and pressurized, its volume expands to block the underground obstacle pipeline 2, which can effectively prevent the loss of slurry for protecting the wall of the trench section 1 and the poured concrete, thereby reducing the risk of collapse of the trench section 1 and ensuring the safety of the trench section 1 and ground construction, with obvious economy. The maintenance shaft 4 is an inspection well for the maintenance of the original underground pipeline before and after, which is convenient for the operator to enter and exit the pipeline and install the engineering airbag 3.

[0037] Step S3: Divide the trench section 1 on-site according to the design drawing, and use the grooving machine 6 to excavate the trench section 1. During this period, the trench section 1 is always filled with slurry, and the slurry density in the trench is controlled through the slurry circulation system to ensure the stability of the trench wall, and the slurry index is adjusted in time. The slurry circulation system is a publicly known slurry preparation and circulation system, such as Figure 4 shown, including various sedimentation tanks, slurry storage tanks, slurry preparation devices, circulation pipelines, etc.; when the hydraulic grab 7 of the grooving machine approaches the underground obstacle pipeline 2, it operates with a small feed rate, first locally and experimentally destroys the wall of the underground obstacle pipeline. Once the height of the slurry changes due to the destruction or the mechanical construction personnel can sense it, the obstacles below the trench section 1 can be directly flushed away, and the situation in the maintenance shaft 4 is checked. If there is a slurry leakage situation, the engineering airbag 3 is pressurized in time; the allowable deviation of the length of the trench section 1 is ±2.0%; the allowable deviation of the thickness of the trench section 1 is +1.5%, -1.0%; the allowable deviation of the perpendicularity of the trench section 1 is ±1 / 300;

[0038] Step S4: After the quality inspection of the trench body, carry out the trench cleaning work. By installing a special wire brush 8 for brushing the trench on the hydraulic grab 7 of the grooving machine, the brushing and cleaning of the side wall of the trench body are completed.

[0039] Step S5: After the trench cleaning work is completed, clean the sediment 9 at the bottom of the trench and complete the replacement of the slurry in the trench body. One hour after the completion of the bottom cleaning and slurry replacement of the trench, the slurry density within a height of 500 mm from the bottom of the trench is not greater than 1.15, and the sediment thickness is not greater than 100 mm.

[0040] Step S6: Use two crawler cranes 11 to cooperate with each other to make the steel reinforcement cage 10 perpendicular to the ground, hoist the steel reinforcement cage 10 to the designed height in the trough, and fix the steel reinforcement cage 10 on the guide wall 5 by passing steel channels through the steel reinforcement cage 10; there is a 500 mm gap between the lower end of the steel reinforcement cage 10 and the trough bottom, and there is a 100 - 150 mm gap between the two end parts on both sides of the steel reinforcement cage 10 and the joint surface of the adjacent diaphragm wall. At the same time, positioning pads are welded on both sides of the steel reinforcement cage 10. There are two columns on each side of the steel reinforcement cage 10 in the horizontal direction, the longitudinal spacing of each positioning pad is 3 - 5 m, and 2 - 3 pieces are arranged in each layer;

[0041] Step S7: Install the concrete pouring conduit 12 along the side wall of the trough, pour concrete into the trough through the concrete pouring conduit 12, and draw out the concrete pouring conduit 12 after the pouring is completed. The concrete solidifies to form a diaphragm wall. The local protrusion of the diaphragm wall surface should not be greater than 100 mm, and the deviation of the center line of the wall top should not be greater than 30 mm; the horizontal layout distance of the concrete pouring conduit 12 should not be greater than 3 m, and the distance from the end of the trough section 1 should not be greater than 1.5 m. The height difference between the bottom surfaces of each concrete pouring conduit 12 should not be greater than 0.3 m; the lower end of the concrete pouring conduit 12 should be 300 - 500 mm away from the trough bottom;

[0042] During the process of pouring concrete, the pouring speed should be fast at the beginning to make the bottom sediment in the trough rise together with the concrete surface. It is necessary to ensure that more than 6 m3 of concrete is continuously poured at one time; the concrete should be continuously poured, and the pouring speed should not be lower than 2 m / h. The length of the conduit buried in the concrete is controlled at 1.5 - 3.0 m, and the height difference of the concrete in the adjacent two conduits should not be greater than 0.5 m.

[0043] Since underwater vibration - free pouring is adopted for the concrete, to meet the strength requirements, the concrete poured through the concrete pouring conduit 12 in the mud should have good workability, large fluidity, and slow setting. Before the concrete pouring, the mud circulation can be carried out through the concrete pouring conduit 12 for more than about 15 min to improve the mud quality in the trough. The concrete should be poured within 4 h after the steel reinforcement cage 10 is sunk into place. If the concrete is not poured within 4 hours, the steel reinforcement cage 10 should be lifted, washed clean and then re - inserted into the trough.

[0044] The above - mentioned is only the preferred embodiment of the present invention, and its description is relatively specific and detailed, but it should not be understood as a limitation to the scope of the invention patent. It should be pointed out that without departing from the concept of the present invention, several improvements and deformations can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A construction method for dealing with underground obstacle pipelines during the trench excavation of diaphragm walls, characterized in that, It includes the following steps: Step S1: Conduct construction survey and locate the sidelines on both sides of the diaphragm wall. Lay out the excavation range of the guide wall by setting out, and carry out trenching until the bottom elevation of the guide wall is reached. Then, bind the steel bars of the guide wall and erect the formwork of the guide wall made of wood. Pour the concrete of the guide wall, and compact the back of the guide wall with clay layer by layer. After the concrete strength of the guide wall reaches 70% of the design strength, remove the formwork of the guide wall made of wood, and finally backfill and compact the clay; Step S2: Locate the depth of the underground obstacle pipeline. Combine with the position of the diaphragm wall in Step S1 to determine the position of the engineering airbag. The operators enter the underground obstacle pipeline from the maintenance shaft, first install and inflate the engineering airbag at the far end, then install and inflate the engineering airbag at the near end, and check whether there is air leakage and the air pressure value; Step S3: Divide the groove section width on-site according to the design drawing, and use the grooving machine to excavate the groove section. During this period, the groove section is always filled with slurry, and the specific gravity of the slurry in the groove is controlled through the slurry circulation system. When the hydraulic grab of the grooving machine is close to the underground obstacle pipeline, operate with a small feed rate. During the construction of the groove section, the slurry should be replenished in time to always maintain the necessary liquid level height. First, locally damage the wall of the obstacle pipeline, replenish fresh slurry in time according to the change of the slurry, and at the same time check and pay attention to the situation in the maintenance shaft. If there is slurry leakage, pressurize the engineering airbag in time; Step S4: After conducting quality inspection on the groove body, carry out the cleaning of the groove. Install a special wire brush for cleaning the groove wall on the hydraulic grab of the grooving machine to complete the cleaning of the side wall of the groove body; Step S5: After the cleaning of the groove is completed, clean the sediment at the bottom of the groove body and complete the replacement of the slurry in the groove body; Step S6: Use 2 crawler cranes to cooperate with each other to make the steel cage perpendicular to the ground, hoist the steel cage to the designed height in the groove body, and fix the steel cage on the guide wall by passing steel channels through the steel cage; Step S7: Install the concrete pouring conduit along the side wall of the groove body, pour the concrete into the groove body through the concrete pouring conduit, and draw out the concrete pouring conduit after the pouring is completed. The concrete solidifies to form the diaphragm wall.

2. The construction method for treating underground obstacle pipelines during the trench excavation of diaphragm walls according to claim 1, wherein: In Step S1, the clear distance between the two side guide walls should be greater than 40 - 60 mm of the design size of the diaphragm wall; the allowable deviation of the parallelism between the inner wall surface of the guide wall and the longitudinal axis of the diaphragm wall is ±10 mm, the allowable deviation of the flatness of the top surface of the guide wall is 5 mm, the allowable deviation of the flatness of the inner wall surface is 3 mm, and the allowable deviation of the perpendicularity of the inner wall surface of the guide wall is 5‰.

3. The construction method for dealing with underground obstacle pipelines during the trench excavation of diaphragm walls according to claim 1, characterized in that: In Step S3, the allowable deviation of the length of the groove section is ±2.0%; the allowable deviation of the thickness of the groove section is +1.5%, -1.0%; the allowable deviation of the perpendicularity of the groove section is ±1 / 300.

4. The construction method for treating underground obstacle pipelines during the trench excavation of diaphragm walls according to claim 1, characterized in that: In Step S5, 1 hour after the completion of the cleaning of the bottom of the groove and the replacement of the slurry, the specific gravity of the slurry within a height of 500 mm from the bottom of the groove is not greater than 1.15, and the sediment thickness is not greater than 100 mm.

5. The construction method for treating underground obstacle pipelines during the trench excavation of diaphragm walls according to claim 1, characterized in that: In Step S6, there is a gap of 500 mm between the lower end of the steel cage and the bottom of the groove. There is a gap of 100 - 150 mm between the two ends of the steel cage on both sides and the joint surface of the adjacent diaphragm wall. At the same time, positioning pads are welded on both sides of the steel cage. There are two columns on each side in the horizontal direction of the steel cage, and the longitudinal spacing of each positioning pad is 3 - 5 m, and 2 - 3 pieces are arranged in each layer.

6. The construction method for dealing with underground obstacle pipelines during the trench excavation of diaphragm wall according to claim 1, characterized in that: The local protrusion of the diaphragm wall surface is not more than 100 mm; the deviation of the center line at the wall top is not more than 30 mm.

7. The construction method for dealing with underground obstacle pipelines during the trench excavation of diaphragm walls according to claim 1, characterized in that: In step S7, the horizontal layout distance of the concrete pouring conduit is not more than 3 m, the distance from the end of the groove section should not be more than 1.5 m, and the height difference of the bottom surfaces of each conduit is not more than 0.3 m; the distance from the lower end of the conduit to the bottom of the groove should be 300 - 500 mm.

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