Soft soil layer combined pipe curtain and large-span underground space excavation construction method

Abstract

The present application belongs to the civil construction technical field, and relates to a soft soil layer combined pipe curtain and large-span underground space excavation construction method, which comprises the following steps: 1) pipe group design: according to the construction surface of the soft soil layer, respectively designing the combined form of the positioning pipe group and the combined form of the penetrating pipe group; 2) positioning pipe group jacking: excavating according to the shape of the construction surface, and jacking a set of positioning pipe groups at different points on the construction surface; 3) penetrating pipe group jacking: jacking the penetrating pipe group between the adjacent positioning pipe groups, and inserting the penetrating pipe group and the positioning pipe group in the form of a casing on the construction surface to form a closed loop combined pipe curtain; and 4) reinforcement grouting: after waterproof treatment and reinforcement of the combined pipe curtain, pouring concrete. The present application provides a soft soil layer combined pipe curtain and large-span underground space excavation construction method, which is constructed by using the combined pipe curtain method, does not need to be frozen, and has the advantages of simple construction, small difficulty and low cost.

Description

Technical Field

[0001] This invention belongs to the field of civil engineering construction technology and relates to a method for constructing a combined pipe jacking system in soft soil strata and a method for excavating large-span underground spaces. Background Technology

[0002] Construction of urban underground spaces, such as subway stations, often uses the open-cut method. This not only involves pipeline relocation and underground drainage, which have a significant impact on the strata and environment, but also greatly affects the production and life of urban residents due to road occupation during construction.

[0003] The pipe jacking method is a common construction method for large-section cut-and-cover tunnels worldwide. It is based on single-pipe jacking, with each pipe connected to the surrounding annular gap by interlocking and grouting to form a sealed, water-stopping pipe jacking. Alternatively, the method of freezing the soil between the pipe jacking sections can be used to freeze and solidify the gaps between the pipe jacking sections, thus achieving a water-stopping effect. Currently, the single-pipe jacking method is commonly used, but it does not have an advantage in terms of construction period and cost. In long-distance construction conditions, the difference will be more significant.

[0004] CN109372521A describes a new pipe jacking construction technology and pipe support device. This technology improves upon existing pipe support processes by pre-supporting the pipes before cutting them. This involves removing a portion of the pipe wall between adjacent pipes, welding steel plates between the arched and inverted arched sections of adjacent pipes, binding reinforcing bars inside the pipes, and then pouring concrete. While this method connects the steel pipes by removing a portion of the pipe wall between adjacent pipes, during construction, all pipes are still jacked in single sections. Setting up support devices before cutting and pouring reinforcing bars after cutting, while ensuring stability, complicates the construction process. Furthermore, for soft soil layers, freezing treatment is required before construction, increasing the difficulty and cost. Summary of the Invention

[0005] To address the technical problems of complex construction, high difficulty and high cost of existing pipe jacking construction methods, this invention provides a combined pipe jacking method for soft soil strata and a method for large-span underground space excavation. The combined pipe jacking method eliminates the need for freezing treatment and has the advantages of simple construction, low difficulty and low cost.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for tunneling large-span underground spaces in soft soil strata includes the following steps:

[0008] 1) Pipe assembly design

[0009] The positioning pipe assembly and the interlocking pipe assembly are designed according to the soft soil stratum construction surface.

[0010] 2) Positioning pipe assembly jacking

[0011] Excavate according to the shape of the construction surface, and jack in a set of positioning pipes at different points on the construction surface;

[0012] 3) Insertion of the tube assembly

[0013] Insert a perforated pipe group between adjacent positioning pipe groups, and connect the perforated pipe group and the positioning pipe group to the construction surface in the form of a sleeve to form a closed-loop combined pipe curtain;

[0014] 4) Reinforcement grouting

[0015] After waterproofing and reinforcing the combined pipe curtain, concrete is poured.

[0016] Further specifying, in step 1), the positioning tube assembly is composed of multiple positioning steel pipes connected in sequence and has openings at both ends; the openings are sealed with fiberglass boards.

[0017] Further specifying, in step 1), the insertion tube group is composed of multiple insertion steel pipes connected in sequence.

[0018] Further defined, in step 3), the outermost steel pipes on both sides of the interpenetrating pipe group are respectively inserted into the positioning steel pipes of the positioning pipe group adjacent to the corresponding side of the interpenetrating pipe group and fastened by connectors, so that the interpenetrating pipe group and the positioning pipe groups on both sides form a closed-loop combined pipe curtain.

[0019] Further specifying, in step 4), the waterproofing treatment includes temporary waterproofing and secondary waterproofing.

[0020] Further specifying, the temporary waterproofing involves setting a sealing gasket between the inserted steel pipe and the positioning steel pipe; the secondary waterproofing involves injecting grout between the pipe walls at the joint of the inserted steel pipe and the positioning steel pipe.

[0021] Further specifying, in step 4), reinforcement involves installing steel cages in both the axial direction of the inserted steel pipe and the axial direction of the positioning steel pipe.

[0022] A composite pipe curtain for soft soil strata, which enables large-span underground space excavation in soft soil strata, includes multiple positioning pipe groups and multiple intersecting pipe groups; the multiple positioning pipe groups and multiple intersecting pipe groups are staggered and connected to form a ring-shaped closed structure.

[0023] Further specifying, the positioning tube assembly is composed of multiple positioning steel pipes connected as one unit, with openings on the side walls of both ends of the positioning steel pipes, and the openings are sealed by fiberglass boards; the insertion tube assembly is composed of multiple insertion steel pipes connected as one unit, with the outermost insertion steel pipe of the insertion tube assembly passing through the fiberglass board and inserted into the positioning steel pipe at the outer end of the positioning tube assembly, the gap between the insertion steel pipe and the positioning steel pipe being filled with a sealing gasket, and the insertion steel pipe being fastened to the positioning steel pipe by a connector.

[0024] Furthermore, there are multiple sealing gaskets and connectors, which are evenly distributed in the circumferential direction between the positioning steel pipe and the through steel pipe.

[0025] The beneficial effects of this invention are:

[0026] 1. This invention uses a combination of positioning pipe groups and interlaced pipe groups to form a combined pipe curtain, which eliminates the need to freeze soft soil layers and install supports inside steel pipes. The strength is stable and meets the requirements, which simplifies the construction process, reduces construction difficulty, and lowers construction costs.

[0027] 2. This invention forms a temporary waterproof barrier at the joint between the positioning pipe assembly and the insertion pipe assembly by setting a sealing gasket; furthermore, grout is injected between the two pipe walls at the joint to form a secondary waterproof barrier, which has strong waterproofing and ensures construction safety.

[0028] 3. This invention uses bolts as connectors and adds nuts inside the steel pipe for locking, ensuring the integrity of the combined pipe curtain structure, enhancing the load-bearing capacity of the pipe curtain, and making it more stable and safer.

[0029] 4. The present invention adopts the combined pipe jacking method for construction, which improves construction efficiency and reduces the number of joints between pipe jacks in the circumferential direction, thereby reducing the risk of water leakage. Attached Figure Description

[0030] Figure 1 A schematic diagram of the combined tube curtain structure provided by the present invention;

[0031] Figure 2 This is a schematic diagram of the structure of the second positioning tube group A2;

[0032] Figure 3 This is a schematic diagram of the structure of the fifth intercalation tube group E;

[0033] Figure 4 A schematic diagram showing the connection between the second positioning tube group A2 and the fifth insertion tube group E;

[0034] Figure 5 for Figure 4 Enlarged schematic diagram of the connection between the second positioning tube group A2 and the fifth insertion tube group E;

[0035] Figure 6 This is a schematic diagram of the structure of the first intercalation tube group C1;

[0036] Figure 7 This is a schematic diagram showing the connection between the third insertion tube group D1, the first insertion tube group C1, and the third positioning tube group B1.

[0037] Figure 8 for Figure 7 Enlarged schematic diagram of the connection between the first perforation tube group C1 and the third perforation tube group D1;

[0038] Figure 9 for Figure 7 Enlarged schematic diagram of the connection between the first insertion tube group C1 and the third positioning tube group B1; wherein:

[0039] A1—First positioning tube group; A2—Second positioning tube group; B1—Third positioning tube group; B2—Fourth positioning tube group;

[0040] C1—First intubation group; C2—Second intubation group; D1—Third intubation group; D2—Fourth intubation group; E—Fifth intubation group; F—Sixth intubation group;

[0041] 1—First positioning steel pipe; 2—Fiberglass board; 3—Second positioning steel pipe; 4—Steel plate; 5—First through steel pipe; 6—Bolt; 7—Sealing gasket; 8—Second through steel pipe. Detailed Implementation

[0042] The present invention provides a combined pipe curtain for soft soil strata, comprising multiple positioning pipe groups and multiple intersecting pipe groups; the multiple positioning pipe groups and multiple intersecting pipe groups are staggered and connected to form a ring-shaped closed structure.

[0043] Specifically, the positioning tube assembly consists of multiple positioning steel pipes connected as a whole, with openings at both ends of the positioning steel pipes, which are then sealed with fiberglass panels. In practice, the openings are made on the side walls of the positioning steel pipes along their axial direction.

[0044] Specifically, the interlocking tube assembly consists of multiple interlocking steel pipes connected together.

[0045] In this invention, when multiple positioning tube assemblies and multiple interlocking tube assemblies are connected in an alternating manner, during the interlocking connection, the outermost interlocking steel tube of the interlocking tube assembly passes through a fiberglass board and inserts into the positioning steel tube, forming a sleeve structure in which the interlocking steel tube is fitted inside the positioning steel tube. Then, the interlocking steel tube is fastened to the positioning steel tube using a connector. The remaining positioning tube assemblies and interlocking tube assemblies are connected in the above manner, making all positioning tube assemblies and interlocking tube assemblies a single unit.

[0046] To enhance sealing, a sealing gasket is filled in the gap between the inserted steel pipe and the positioning steel pipe before tightening, forming a temporary water-stopping structure.

[0047] Multiple gaskets and connectors are provided, evenly distributed along the circumference between the positioning steel pipe and the inserting steel pipe. Preferably, there are at least three gaskets and connectors.

[0048] The present invention provides a method for the construction of large-span underground spaces in soft soil strata using the cut-and-cover method, which includes the following steps.

[0049] 1) Pipe assembly design

[0050] The positioning pipe assembly and the interlocking pipe assembly are designed according to the soft soil stratum construction surface.

[0051] The positioning pipe assembly consists of multiple positioning steel pipes connected in sequence, with openings at both ends; the openings are sealed with fiberglass panels. The insertion pipe assembly consists of multiple insertion steel pipes connected in sequence.

[0052] 2) Positioning pipe assembly jacking

[0053] Excavate according to the shape of the construction surface, and jack in a set of positioning pipes at different points on the construction surface.

[0054] Specifically, multiple positioning points are designed based on the construction surface, and a set of positioning pipes is pushed into each positioning point.

[0055] 3) Insertion of the tube assembly

[0056] Insert a perforated pipe group between adjacent positioning pipe groups, and connect the perforated pipe group and the positioning pipe group to the construction surface in a sleeve manner to form a closed-loop combined pipe curtain.

[0057] In this step, the outermost steel pipes on both sides of the interpenetrating pipe group are inserted into the positioning steel pipes of the adjacent positioning pipe groups on the corresponding sides of the interpenetrating pipe group, and fastened with connectors. The interpenetrating pipe group and the positioning pipe groups on both sides form a closed-loop combined pipe curtain. Because the interpenetrating pipe group is set between the two positioning pipe groups during installation, the outermost steel pipe on one side of the interpenetrating pipe group is inserted into the positioning steel pipe of the adjacent positioning pipe group, and the outermost steel pipe on the other side of the interpenetrating pipe group is inserted into the positioning steel pipe of the adjacent positioning pipe group. This makes the two positioning pipe groups and the interpenetrating pipe group form a whole. All positioning pipe groups and interpenetrating pipe groups are connected in this way to form a closed-loop combined pipe curtain.

[0058] Specifically, after the combined pipe curtain forms a closed loop, holes are drilled and threads are formed on the steel plates of the two layers of steel pipes (intercalating steel pipes and positioning steel pipes) using an electric drill and a threading machine. The threads are then tightened with bolts 6, and nuts are added inside the steel pipes (intercalating steel pipes) to form a complete ring structure.

[0059] 4) Reinforcement grouting

[0060] After waterproofing and reinforcing the combined pipe curtain, concrete is poured.

[0061] In this step, waterproofing treatment includes temporary waterproofing and secondary waterproofing.

[0062] Preferably, temporary waterproofing involves placing a sealing gasket between the inserted steel pipe and the positioning steel pipe.

[0063] Preferably, secondary waterproofing involves injecting grout between the pipe walls at the joint between the inserted steel pipe and the positioning steel pipe.

[0064] In this step, reinforcement involves installing steel cages along both the axial direction of the inserted steel pipe and the axial direction of the positioning steel pipe.

[0065] The technical solution of the present invention will be described in detail below with specific implementation examples.

[0066] Example

[0067] In this embodiment, the soft soil stratum combined pipe curtain includes multiple positioning pipe groups and multiple intersecting pipe groups; the multiple positioning pipe groups and multiple intersecting pipe groups are staggered and connected to form a ring-shaped closed structure.

[0068] See Figure 1 The positioning tube group consists of four parts: the first positioning tube group A1, the second positioning tube group A2, the third positioning tube group B1, and the fourth positioning tube group B2.

[0069] The insertion tube group consists of six tubes: the first insertion tube group C1, the second insertion tube group C2, the third insertion tube group D1, the fourth insertion tube group D2, the fifth insertion tube group E, and the sixth insertion tube group F.

[0070] The diameter of the steel pipes in the combined pipe curtain is between 100cm and 200cm.

[0071] The positioning tube groups and the interpenetrating tube groups are distributed at intervals and are staggered to form a closed ring structure. For example, the tube groups start from the first positioning tube group A1 at the top and are connected in a clockwise direction in sequence to the fifth interpenetrating tube group E, the second positioning tube group A2, the fourth interpenetrating tube group D2, the second interpenetrating tube group C2, the fourth positioning tube group B2, the sixth interpenetrating tube group F, the third positioning tube group B1, the first interpenetrating tube group C1, and the third interpenetrating tube group D1, and finally return to the first positioning tube group A1 to form a closed ring structure.

[0072] The top of the construction surface is formed by connecting the first positioning pipe group A1, the fifth interpenetrating pipe group E, and the second positioning pipe group A2. Since the top of the construction surface is arc-shaped, the first positioning pipe group A1, the fifth interpenetrating pipe group E, and the second positioning pipe group A2 are all arc-shaped pipe groups, and the structures of the first positioning pipe group A1 and the second positioning pipe group A2 are the same, and they are distributed in a mirror symmetrical manner.

[0073] See Figure 2The second positioning tube group A2 consists of five positioning steel pipes, including two first positioning steel pipes 1 and three second positioning steel pipes 3. The three second positioning steel pipes 3 are arranged in a crisscross pattern according to the curvature of the construction surface. The crisscrossing parts are cut and connected by steel plates 4. The surface of the steel plates 4 is perpendicular to the axis of the second positioning steel pipes 3. Then, a first positioning steel pipe 1 is connected to each end of the three second positioning steel pipes 3 to form a whole. The first positioning steel pipes 1 and the second positioning steel pipes 3 intersect. The part of the second positioning steel pipe 3 that extends into the first positioning steel pipe 1 is cut. Openings are made at the outermost ends of the two first positioning steel pipes 1. Fiberglass plates 2 are placed on the openings to close the second positioning tube group A2.

[0074] See Figure 3 Specifically, the fifth interpenetrating tube group E is composed of four first interpenetrating steel pipes 5 connected in sequence. The adjacent first interpenetrating steel pipes 5 intersect each other, and the intersecting parts are cut and connected by steel plates 4. The surface of the steel plate 4 is perpendicular to the axis of the first interpenetrating steel pipes 5.

[0075] The first positioning tube group A1 and the second positioning tube group A2 have the same structure and are mirror images of each other. The first positioning tube group A1 is connected to the second positioning tube group A2 through the fifth interpenetrating tube group E, and an interpenetrating tube group is set between the two positioning tube groups.

[0076] See Figure 4 and Figure 5 The fifth insertion tube group E has two openings at both ends of the first positioning steel pipe 1. When connected, the first insertion steel pipe 5 at the left end is inserted into the first positioning steel pipe 1 at the right end of the first positioning tube group A1, and the first insertion steel pipe 5 at the right end is inserted into the first positioning steel pipe 1 at the left end of the second positioning tube group A2. The insertion joint forms a sleeve with the first positioning steel pipe 1 on the outside and the first insertion steel pipe 5 on the inside. Furthermore, a sealing gasket 7 is set on the inner wall of the first positioning steel pipe 1. After insertion, a temporary water-stopping structure is formed between the first insertion steel pipe 5 and the first positioning steel pipe 1 due to the action of the sealing gasket 7. There are four sealing gaskets 7, which are evenly arranged in the circumferential direction of the first insertion steel pipe 5.

[0077] To improve the stability of the connection, the first through steel pipe 5 and the first positioning steel pipe 1 are connected by a connector.

[0078] The bottom of the construction surface is formed by connecting the third positioning pipe group B1, the sixth intercalation pipe group F, and the fourth positioning pipe group B2. Since the bottom of the construction surface is horizontal, the third positioning pipe group B1, the sixth intercalation pipe group F, and the fourth positioning pipe group B2 are all straight pipe groups.

[0079] The tube configurations of the third positioning tube group B1 and the fourth positioning tube group B2 are the same as those of the second positioning tube group A2, except that both the third and fourth positioning tube groups B1 and B2 are straight tube groups. The sixth intercalation tube group F is a straight tube group composed of three intercalation tubes, and the combination method between the three intercalation tubes is the same as the connection combination method of the fifth intercalation tube group E. When the third positioning tube group B1, the sixth intercalation tube group F, and the fourth positioning tube group B2 are connected in sequence, the connection method is the same as the connection method of the first positioning tube group A1 through the fifth intercalation tube group E and the second positioning tube group A2.

[0080] The top and bottom of the construction surface are connected by interlocking pipe groups. Specifically, the first positioning pipe group A1 and the third positioning pipe group B1 are connected by the first interlocking pipe group C1 and the third interlocking pipe group D1, and the second positioning pipe group A2 and the fourth positioning pipe group B2 are connected by the second interlocking pipe group C2 and the fourth interlocking pipe group D2.

[0081] See Figure 6 The first insertion tube group C1 consists of four insertion steel pipes, and the third insertion tube group D1 consists of three insertion steel pipes. In order to ensure the stability between the first insertion tube group C1 and the third insertion tube group D1, the insertion steel pipe at the connecting end of the third insertion tube group D1 is inserted into the insertion steel pipe at the connecting end of the first insertion tube group C1.

[0082] For example, the first perforated tube group C1 consists of three first perforated steel pipes 5 and one second perforated steel pipe 8 connected sequentially. Adjacent first perforated steel pipes 5 are cross-connected, and the cross-connected portions are cut and then connected by a steel plate 4. The surface of the steel plate 4 is perpendicular to the axial direction of the first perforated steel pipes 5. A second perforated steel pipe 8 is connected to one end of a first perforated steel pipe 5. The first and second perforated steel pipes 5 are cross-connected, and the portion of the first perforated steel pipe 5 extending into the second perforated steel pipe 8 is cut. An opening is provided at the outer end of the second perforated steel pipe 8, and the opening is sealed with a fiberglass board 2. The third perforated tube group D1 consists of three first perforated steel pipes 5 connected sequentially, adjacent first perforated steel pipes 5 being cross-connected, and the cross-connected portions are cut and then connected by a steel plate 4. The surface of the steel plate 4 is perpendicular to the axial direction of the first perforated steel pipes 5.

[0083] The second insertion tube group C2 is composed in the same way as the first insertion tube group C1, and the first insertion tube group C1 and the second insertion tube group C2 are mirror images of each other. The fourth insertion tube group D2 is composed in the same way as the third insertion tube group D1, and the fourth insertion tube group D2 and the third insertion tube group D1 are mirror images of each other.

[0084] The first insertion tube group C1, the second insertion tube group C2, the third insertion tube group D1, and the fourth insertion tube group D2 are all arc-shaped tube groups.

[0085] See Figure 7 , Figure 8 and Figure 9 The connections between the first positioning tube group A1, the third insertion tube group D1, the first insertion tube group C1, and the third positioning tube group B1 are as follows: The first insertion steel pipe 5 at one end of the third insertion tube group D1 is inserted into the first positioning steel pipe 1 at the left end of the first positioning tube group A1; the first insertion steel pipe 5 at the other end of the third insertion tube group D1 is inserted into the second insertion steel pipe 8 at one end of the first insertion tube group C1; the first insertion steel pipe 5 at the other end of the first insertion tube group C1 is inserted into the first positioning steel pipe 1 at the left end of the third positioning tube group B1; and a temporary water-stopping structure is formed between the first positioning steel pipe 1 and the first insertion steel pipe 5 through a sealing gasket 7. A temporary water-stopping structure is also formed between the second insertion steel pipe 8 and the first insertion steel pipe 5 through a sealing gasket 7.

[0086] See Figure 1 The connection between the second positioning tube group A2, the fourth insertion tube group D2, the second insertion tube group C2, and the fourth positioning tube group B2 shall be in accordance with the connection method described above.

[0087] To improve the stability of the connection, the first through steel pipe 5 and the first positioning steel pipe 1 are connected by a connector, and the second through steel pipe 8 and the first through steel pipe 5 are also connected by a connector.

[0088] In this embodiment, the connector is preferably bolted. In practice, holes are drilled in the two steel pipes of the ferrule using an electric drill and a threading machine to form threads. The bolts are then tightened, and nuts are added inside the steel pipes to form a complete ring structure.

[0089] The use of the aforementioned combined pipe jacking method for tunneling in soft soil strata improves efficiency, reduces the number of joints between pipe jacks in the circumferential direction, and lowers the risk of water leakage compared to single-pipe pipe jacking. The specific construction process is as follows.

[0090] (1) First, determine the combination of multiple positioning pipe groups and multiple insertion pipe groups based on the construction surface (door opening shape).

[0091] Specifically, the following groups are identified: the first positioning tube group A1, the second positioning tube group A2, the third positioning tube group B1, the fourth positioning tube group B2, the first insertion tube group C1, the second insertion tube group C2, the third insertion tube group D1, the fourth insertion tube group D2, the fifth insertion tube group E, and the sixth insertion tube group F. The combination form and structural shape of these tube groups are as described above.

[0092] (2) Construction of working well

[0093] Before jacking the combined pipe jacking, a working shaft is constructed first. The working shaft can be constructed using either open-cut or cut-and-cover methods, and its retaining structure is a diaphragm wall or cement-mixing piles. The diaphragm wall thickness is 0.8m–1.6m. A reaction device is installed inside the working shaft. An opening is made at the jacking position of the combined pipe jacking, and a steel sleeve is embedded there. The length of the steel sleeve is the same as the thickness of the diaphragm wall, and the thickness of the steel sleeve is 4–6cm. The steel sleeve is welded to the reinforcing steel of the diaphragm wall, and the gap between the steel sleeve and the opening is filled with cement grout. The steel sleeve is used as the positioning pipe for the combined pipe jacking, and its diameter is 2–4mm larger than the diameter of the corresponding steel pipe in the combined pipe jacking.

[0094] (3) Positioning tube assembly jacking

[0095] The first positioning pipe assembly A1 is jacked in from the top left side of the construction surface inside the working well, the second positioning pipe assembly A2 is jacked in from the top left side, the third positioning pipe assembly B1 is jacked in from the bottom left side, and the fourth positioning pipe assembly B2 is jacked in from the bottom right side. There is no specific order in which these four positioning pipe assemblies are jacked in.

[0096] (4) Insertion of the tube assembly

[0097] The fifth inserting tube group E is pushed in between the first positioning tube group A1 and the second positioning tube group A2, and the sixth inserting tube group F is pushed in between the third positioning tube group B1 and the fourth positioning tube group B2. During the pushing, the inserting steel pipes are all inserted into the positioning steel pipes to form a sleeve structure.

[0098] Then, the first insertion tube group C1 and the second insertion tube group C2 are inserted respectively. The insertion connection of the first insertion tube group C1 and the third positioning tube group B1 forms a sleeve structure; the insertion connection of the second insertion tube group C2 and the fourth positioning tube group B2 forms a sleeve structure.

[0099] Finally, the third and fourth interlocking pipe groups D1 and D2 are jacked in; one end of the third interlocking pipe group D1 is connected to the first positioning pipe group A1 to form a sleeve structure, and the other end of the third interlocking pipe group D1 is connected to the first interlocking pipe group C1 to form a sleeve structure; one end of the fourth interlocking pipe group D2 is connected to the second positioning pipe group A2 to form a sleeve structure, and the other end of the fourth interlocking pipe group D2 is connected to the second interlocking pipe group C2 to form a sleeve structure. All pipe groups are connected on the construction surface to form a combined pipe curtain with a ring-shaped closed structure.

[0100] On the combined tube curtain, the connection between the tube groups is fastened by connectors, that is, the sleeve structure is formed at the connection and fastened by connectors, and the connectors are connected by bolts 6.

[0101] In steps (3) and (4), the jacking construction methods for each positioning pipe group and each intersecting pipe group of the combined pipe curtain all adopt the existing pipe curtain jacking technology. During construction, the equipment used in the jacking process is conventional pipe curtain construction equipment. For example, laser guidance is used for positioning during jacking construction, and the jacking direction of each pipe group of the combined pipe curtain is controlled by adjusting the thrust of the rear jacks and the angle of the jacking iron; for example, foam spraying is set in front of the cutterhead of the pipe curtain machine during jacking to reduce the friction between the pipe curtain and the stratum, and mud spraying pipe and a mixer are set behind the cutterhead. After the cutterhead cuts the soil, it is mixed with mud, and the mixture of soil and mud is discharged through the mud discharge pipe to complete the excavation. At the same time, in the jacking process, the cutterhead is designed with three in front and two in back, or two in front and three in back. This is because each pipe group has multiple steel pipes, so existing combined cutter heads (matched to the pipe group connection) are used for construction; and multiple steel pipes are on the same plane, and adjacent cutter heads are staggered and distributed, so they will not affect each other, thus improving construction efficiency.

[0102] (5) Grouting reinforcement

[0103] After waterproofing and reinforcement of the closed-loop combined pipe curtain, concrete is poured, and the construction is completed.

[0104] A sealing gasket 7 is installed between the sleeves (positioning steel pipe and through steel pipe) at the connection point to form a temporary water stop. Grout is injected between the pipe walls at the connection joint (between the positioning steel pipe and through steel pipe) to form a secondary waterproofing, preventing water from seeping into the soft soil layer and effectively solving the waterproofing problem during construction.

[0105] Preferably, the slurry is a resin-based slurry with high fluidity.

[0106] Preferably, the reinforcement involves installing steel cages along both the axial direction of the inserted steel pipe and the axial direction of the positioning steel pipe, and then pouring concrete to complete the construction.

[0107] In this embodiment, the soil inside the pipe jacking is excavated using the step method or other sectional excavation methods. After the tunnel construction is completed, the internal decorative structure can be constructed. Furthermore, during construction, a bidirectional alternating method is used to advance the combined pipe jacking, i.e., two opposing working shafts are excavated, denoted as A and B. The combined pipe jacking is advanced from one working shaft (A), and after reaching the other working shaft (B), the pipe jacking machine is removed and then pushed back from working shaft (B), repeating this process to improve construction efficiency.

[0108] This invention utilizes a combined pipe jacking system for underground excavation, which offers excellent stability and eliminates the need for freezing treatment in soft soil layers, significantly reducing construction difficulty, simplifying the construction process, shortening construction time, and lowering costs.

[0109] The above is one preferred embodiment of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the invention.

Claims

1. A method for tunneling large-span underground spaces in soft soil strata, characterized in that, Includes the following steps: 1) Pipe assembly design The combination forms of positioning pipe groups and interlocking pipe groups are designed according to the construction surface of soft soil strata. 2) Positioning pipe assembly jacking Excavate according to the shape of the construction surface, and jack in a set of positioning pipes at different points on the construction surface; 3) Insertion of the tube assembly Insert a perforated pipe group between adjacent positioning pipe groups, and connect the perforated pipe group and the positioning pipe group to the construction surface in the form of a sleeve to form a closed-loop combined pipe curtain; 4) Reinforcement grouting After waterproofing and reinforcing the closed-loop combined pipe curtain, concrete is poured.

2. The method for large-span underground space excavation in soft soil strata according to claim 1, characterized in that, In step 1), the positioning tube group is composed of multiple positioning steel pipes connected in sequence, and openings are provided on the positioning steel pipes at both ends of the positioning tube group; the openings are sealed with fiberglass boards.

3. The method for large-span underground space excavation in soft soil strata according to claim 1, characterized in that, In step 1), the insertion tube group is composed of multiple insertion steel pipes connected in sequence.

4. The method for large-span underground space excavation in soft soil strata according to claim 1, characterized in that, In step 3), the outermost steel pipes on both sides of the insertion pipe group are respectively inserted into the positioning steel pipes of the positioning pipe group adjacent to the corresponding side of the insertion pipe group and fastened by connectors, so that the insertion pipe group and the positioning pipe groups on both sides form a closed-loop combined pipe curtain.

5. The method for large-span underground space excavation in soft soil strata according to claim 1, characterized in that, In step 4), the waterproofing treatment includes temporary waterproofing and secondary waterproofing.

6. The soft soil layer large-span underground space underground excavation construction method according to claim 5, characterized in that, The temporary waterproofing involves placing a sealing gasket between the through-pipe and the positioning pipe; the secondary waterproofing involves injecting grout between the pipe walls at the joint between the through-pipe and the positioning pipe.

7. The method for tunneling large-span underground spaces in soft soil strata according to claim 6, characterized in that, In step 4), reinforcement involves installing steel cages in both the axial direction of the inserted steel pipe and the axial direction of the positioning steel pipe.

8. A composite pipe jacking system for soft soil strata, constructed using the tunnel excavation method for large-span underground spaces in soft soil strata as described in claim 1, characterized in that... The soft soil stratum combined pipe curtain includes multiple positioning pipe groups and multiple intersecting pipe groups; the multiple positioning pipe groups and multiple intersecting pipe groups are staggered and connected to form a ring-shaped closed structure.

9. The composite pipe curtain for soft soil strata according to claim 8, characterized in that, The positioning tube assembly is composed of multiple positioning steel pipes connected together. Openings are made on the side walls of the positioning steel pipes at both ends of the positioning tube assembly, and the openings are sealed with fiberglass boards. The insertion tube assembly is composed of multiple insertion steel pipes connected together. The outermost insertion steel pipe of the insertion tube assembly passes through the fiberglass board and is inserted into the positioning steel pipe at the outer end of the positioning tube assembly. The gap between the insertion steel pipe and the positioning steel pipe is filled with a sealing gasket. The insertion steel pipe is fastened to the positioning steel pipe by a connector.

10. The composite pipe curtain for soft soil strata according to claim 9, characterized in that, There are multiple sealing gaskets and connectors, which are evenly distributed in the circumferential direction between the positioning steel pipe and the through steel pipe.

Images