Shield end reinforcing structure construction method

Abstract

The invention relates to the technical field of diversion tunnel construction, in particular to a construction method of a shield end reinforcing structure. A three-shaft mixing pile and high-pressure jet grouting pile combined reinforcing construction method is adopted to construct a formed end reinforcing body; a high-pressure jet grouting pile construction method is adopted to construct and form the retaining wall; a cement mixing pile TRD construction method is adopted to construct and form the water stop curtain wall; a cement mixing pile TRD construction method is adopted to construct and form the lining wall; and after the construction of the main body structure is completed, the gap between the lining wall and the water stop curtain wall adopts a triple-pipe high-pressure jet grouting pile construction method to form the caulking reinforcing layer. Thus, on one hand, the structural stability of the caulking reinforcing layer is extremely high, the caulking reinforcing layer keeps good bonding strength relative to the water stop curtain wall and the lining wall, and the generation process of water seepage cracks is restrained; and on the other hand, the lining wall is extremely good in continuity and has good waterstop performance, and even in the face of complex geological conditions, the structural steel inserted in the construction process is beneficial to improving the construction safety during tunnel portal chiseling.

Description

Technical Field

[0001] The invention relates to the technical field of water diversion tunnel construction, in particular to a shield end reinforcement structure construction method. Background Art

[0002] As shield construction technology becomes more mature and shield construction becomes more widespread, how to avoid shield construction risks is a key issue in construction. According to statistics on shield construction accidents in recent years, shield construction accidents mostly occur in the starting and receiving stages. Therefore, on the basis of the shaft enclosure structure, special reinforcement design is also required for the starting and receiving sections.

[0003] When the shield machine is in and out of the tunnel, the working face is in an open state for a long time. If the treatment method is not appropriate, groundwater, quicksand, and mud will easily penetrate into the shaft, and in severe cases, it may even cause the tunnel gate to collapse. Therefore, the shaft end needs to be structurally reinforced. The main purpose is to ensure the safety when the tunnel gate is broken, so that the soil at the end has a certain self-stabilizing ability and cuts off the connection between the reinforced area and the outside water. Therefore, the shield end reinforcement design will directly determine the success or failure of the shield start or reach.

[0004] As far as the current status of the industry is concerned, safety accidents such as water and sand gushing are very likely to occur during construction in soft and water-rich areas. Once such accidents occur, in addition to damage to the main structure of the tunnel project, they will also cause serious social impacts. The reason is that there is no caulking reinforcement layer between the water-stop curtain wall and the inner lining wall, which plays a role in stopping water and preventing gushing, or the lateral load and torque bearing capacity of the caulking reinforcement layer is insufficient. In actual applications, the water-stop curtain wall is very easy to crack due to separation from the inner lining wall. Furthermore, the reinforcement strength of the inner lining wall formed by conventional high-pressure rotary jet piles and deep mixing piles is insufficient, and it is very easy to collapse during the construction of tunnel door chiseling, especially when the open state lasts for a long time, which endangers construction safety. Therefore, technical personnel are urgently needed to solve the above problems. Summary of the invention

[0005] Therefore, in view of the above-mentioned existing problems and defects, the research and development team of the present invention collected relevant information, conducted multi-party evaluations and considerations, and continuously experimented and modified the research and development team, which eventually led to the emergence of the shield end reinforcement structure construction method.

[0006] In order to solve the above technical problems, the present invention relates to a shield end reinforcement structure construction method, which is applicable to the reinforcement construction of the shield starting tunnel and the shield receiving tunnel. The shield end reinforcement structure includes a retaining wall, a water-stop curtain wall, a caulking reinforcement layer, an inner lining wall and an end reinforcement body, and is arranged in sequence along the direction of penetrating into the soil;

[0007] The construction method of the shield end reinforcement structure is:

[0008] The reinforcement method of combining three-axis mixing piles and high-pressure jet grouting piles is used to construct the end reinforcement body, and the strong reinforcement construction method is used for the soil layer 4m above the tunnel top and 1m below the bottom of the caisson blade. The strong reinforcement strength is controlled at 1~1.8Mpa, and the permeability coefficient is not greater than 1.2*10 -7 cm / s; while the disturbed soil within the reinforcement range adopts weak reinforcement construction method;

[0009] High-pressure jet grouting method is used to construct the retaining wall 0.5m in front of the tunnel entrance;

[0010] The cement mixing pile TRD method is used to construct the water-stop curtain wall;

[0011] The cement mixing pile TRD method is used to construct the inner lining wall, and the inner lining wall is embedded with steel. Before the shield starts / receives, the steel is removed;

[0012] After the main structure is completed, the gap between the lining wall and the water-stop curtain wall is filled with a caulking reinforcement layer using a triple-tube high-pressure jet grouting method. The thickness of the caulking reinforcement layer is no less than 50cm.

[0013] As a further improvement of the technical solution disclosed in the present invention, the reinforcement range of the end reinforcement body is 3m on both sides of the tunnel structure, 3m below, and 8m above, and the longitudinal direction is not less than the length of the shield machine head.

[0014] As a further improvement of the technical solution disclosed in the present invention, in the strong reinforcement construction stage of the end reinforcement, a three-axis mixing pile method with a diameter of Φ500-580mm and a close-packed bite of 100-120mm is adopted, and the cement content is controlled at 18-20%; and in the weak reinforcement construction stage, a high-pressure rotary jet pile method is adopted, and the cement content is controlled at 12-14%.

[0015] As a further improvement of the technical solution disclosed in the present invention, in the stage of constructing the retaining wall, a high-pressure rotary jet pile method with a diameter of 600 to 650 mm and a close-packed bite of 150 to 180 mm is adopted.

[0016] As a further improvement of the technical solution disclosed in the present invention, after the vertical shaft sinks and the foundation stabilizes, a formed end reinforcement body is constructed.

[0017] As a further improvement of the technical solution disclosed in the present invention, during the construction of the inner lining wall, the outer dimensions of the steel section are 700*300*24, and the cement content is controlled at 26-30%.

[0018] As a further improvement of the technical solution disclosed in the present invention, during the solidification of the retaining wall, a Q235 steel ring is implanted, and fixing screw holes are reserved on the steel ring, and the sealing rubber plate and the portal flap are connected to the steel ring by means of bolts.

[0019] As a further improvement of the technical solution disclosed in the present invention, before the shield starts, the integrity and water-stopping effect of the portal area of ​​the retaining wall are verified; for the portal area, a plurality of evenly distributed horizontal detection holes are drilled on the retaining wall.

[0020] As a further improvement of the technical solution disclosed in the present invention, during the construction stage of forming the water-stop curtain wall, the cement content is controlled at 28-30%.

[0021] As a further improvement of the technical solution disclosed in the present invention, a drainage well is provided within the end reinforcement body, and the drainage well does not penetrate the end reinforcement body.

[0022] In practical applications, the shield end reinforcement structure construction method disclosed in the present invention can achieve at least the following beneficial technical effects, specifically:

[0023] 1) Thanks to the triple-tube high-pressure jet-jet pile construction method, the caulking reinforcement layer has extremely high structural stability, good lateral load and torque bearing capacity, and can adapt to different geological conditions; more importantly, the caulking reinforcement layer maintains good bonding strength with respect to the water-stop curtain wall and the lining wall, forming an organic force-bearing whole, which can effectively inhibit the formation of water seepage cracks;

[0024] 2) During the actual construction phase of the joint reinforcement layer, there is no need to dig a deep foundation pit or embed steel bars, which helps reduce the use of manpower and materials, and greatly reduces the construction period and construction costs;

[0025] 3) Thanks to the cement mixing pile TRD method, the lining wall formed by the construction has excellent continuity, eliminating the bad bite phenomenon, ensuring good water-stopping performance even in complex geological conditions, and the construction accuracy is not affected by the depth of the stratum. Furthermore, during the construction period, steel sections can be inserted at intervals, which can not only effectively ensure the construction safety when the tunnel door is chiseled out, but also effectively improve the construction efficiency;

[0026] 4) According to the different pre-construction areas, construction spaces and geological conditions of the end reinforcement bodies, three-axis mixing piles or high-pressure rotary jet piles are flexibly selected. In this way, while ensuring that the end reinforcement bodies have a good reinforcement effect on the tunnel, it is beneficial to control the construction cost and construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 It is a cross-sectional view of the shield starting end reinforcement structure disclosed in the present invention.

[0029] Figure 2 It is a plan layout diagram of the shield starting end reinforcement structure disclosed in the present invention.

[0030] 1-retaining wall; 2-waterstop curtain wall; 3-caulking reinforcement layer; 4-lining wall; 5-end reinforcement body. DETAILED DESCRIPTION

[0031] In view of the fact that the technical effects to be achieved are basically the same, that is, to enhance the strength of the soil outside the tunnel portal, control the surface settlement, and prevent the end collapse, the shield end reinforcement structure disclosed in the present invention is not only suitable for the reinforcement construction of the shield starting tunnel portal, but also for the reinforcement construction of the shield receiving tunnel portal.

[0032] The contents disclosed in the present invention are further described in detail below in conjunction with specific embodiments. Figure 1 , Figure 2 The cross-sectional view and the plan view of the shield starting end reinforcement structure disclosed in the present invention are respectively shown. It can be seen that it includes a retaining wall 1, a water-stop curtain wall 2, a caulking reinforcement layer 3, an inner lining wall 4 and an end reinforcement body 5, and is arranged in sequence along the direction from the vertical shaft into the soil.

[0033] The construction method of the shield end reinforcement structure is:

[0034] After the foundation is stabilized after the shaft is sunk, a reinforcement method combining triaxial mixing piles and high-pressure rotary jet grouting piles is used to construct the end reinforcement body 5. The reinforcement range of the end reinforcement body 5 is 3m on both sides of the tunnel structure, 3m below, and 8m above, and the longitudinal direction is not less than the length of the shield machine head. According to the different pre-construction areas, construction space and geological conditions of the end reinforcement body, triaxial mixing piles or high-pressure rotary jet grouting piles are flexibly selected. In this way, while ensuring that the end reinforcement body 5 has a good reinforcement effect on the tunnel, it is beneficial to control the construction cost and construction period.

[0035] A high-pressure jet grouting pile method (construction parameters: Φ600-650mm, close-packed bite 150-180mm) is used to construct a retaining wall 1 0.5m in front of the tunnel entrance;

[0036] The cement mixing pile TRD method is used to construct the water-stop curtain wall 2, and the cement content is controlled at 28-30% to ensure that the water-stop curtain wall 2 has good structural stability and water-stop performance;

[0037] The cement mixing pile TRD method is used to construct the inner lining wall 4, and the inner lining wall 4 is embedded with steel. The steel is preferably an H-shaped steel with a large cross-sectional area and excellent structural stability. Its overall dimensions are 700*300*24, and the cement content is controlled at 26-30% during the pouring construction process. Remove the steel before the shield starts / receives;

[0038] After the main structure is constructed, the gap between the lining wall 4 and the water-stop curtain wall 2 is formed by a triple-tube high-pressure jet grouting method to form a caulking reinforcement layer 3. The forming thickness of the caulking reinforcement layer 3 is not less than 50 cm.

[0039] In practical applications, the shield end reinforcement structure construction method disclosed in the present invention has achieved at least the following beneficial technical effects, specifically:

[0040] 1) Thanks to the triple-tube high-pressure jet-jet pile construction method, the caulking reinforcement layer 3 formed by the construction has extremely high structural stability, good lateral load and torque bearing capacity, and can adapt to different geological conditions; more importantly, the caulking reinforcement layer 3 maintains good bonding strength with respect to the water-stop curtain wall 2 and the lining wall 4, forming an organic force-bearing whole, which can effectively inhibit the formation of water seepage cracks;

[0041] 2) Thanks to the cement mixing pile TRD method, the inner lining wall 4 formed by the construction has excellent continuity, eliminating the bad bite phenomenon, ensuring good water-stopping performance even in complex geological conditions, and the construction accuracy is not affected by the depth of the stratum. Furthermore, during the construction period, steel sections can be embedded in the inner lining wall 4 at intervals, which can not only effectively ensure the construction safety when the tunnel door is chiseled out, but also effectively improve the construction efficiency.

[0042] It should be emphasized here that during the actual construction stage of the caulking reinforcement layer 3, there is no need to excavate a deep foundation pit or embed steel bars, which helps reduce the use of manpower and materials, and greatly reduces the construction period and construction costs.

[0043] On the premise of ensuring that the 5 end reinforcement bodies have a good reinforcement effect on the soil layer of the shield starting section, in order to reduce the comprehensive construction cost and construction difficulty, as a further optimization of the above technical solution, according to the different pre-construction areas of the end reinforcement bodies and geological conditions, it is divided into strong reinforcement construction areas and weak reinforcement construction areas. For the Suzhou Xujiang Water Diversion Project, the soil layer 4m above the top of the tunnel and 1m below the bottom of the caisson blade is defined as a strong reinforcement construction area, and the easily disturbed soil within the reinforcement range is defined as a weak reinforcement construction area. During the construction stage of the strong reinforcement construction area, the Φ500~580mm densely packed bite 100~120mm three-axis mixing pile method is adopted, the cement content is controlled at 18~20%, and the strong reinforcement strength is controlled at 1~1.8Mpa, and the permeability coefficient is not greater than 1.2*10-7 cm / s; during the construction phase in the weak reinforcement construction area, the three-axis mixing pile method was adopted, and the cement content was controlled at 12-14%.

[0044] According to long-term construction experience, when the shield machine is passing through the starting section and the receiving end, it is very easy to have the risk of groundwater, quicksand and mud infiltration into the shaft. In view of this, as a further optimization of the above technical solution, during the solidification of the retaining wall 1, a Q235 steel ring is implanted, and a fixing screw hole is reserved on the steel ring, and the sealing rubber plate and the portal flap are connected to the steel ring with the help of bolts. In this way, when the shield exit is sealed, the sealing rubber plate will be close to the portal flap under the action of the water and soil pressure in front, forming a reliable sealing state, thereby effectively preventing the risk of groundwater, quicksand and mud infiltration.

[0045] It is known that the molding quality and water-stopping effect of the retaining wall largely determine the final effect of the shield end reinforcement. In view of this, as a further optimization of the above technical solution, before the shield starts, the integrity and water-stopping effect of the portal area of ​​the retaining wall 1 are also verified. For the portal area, a plurality of uniformly distributed horizontal detection holes are drilled on the retaining wall 1.

[0046] Finally, it should be noted that a precipitation well is provided within the end reinforcement body 5, and the precipitation well does not penetrate the end reinforcement body 5 (not shown in the figure). In this way, the precipitation well not only has a drainage function, but also can cut off the flow path of groundwater. When the formation water level is high, the precipitation well can effectively reduce the penetration pressure of groundwater, ensure the safety and stability of the shield starting end, and help reduce the risk of water seepage in the tunnel forming section.

[0047] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest range of convergences with the principles and novel features disclosed herein.

Claims

1. A shield end reinforcement structure construction method, which is applicable to the reinforcement construction of the shield starting tunnel and the shield receiving tunnel; the shield end reinforcement structure includes a retaining wall, a water-stop curtain wall, a caulking reinforcement layer, an inner lining wall and an end reinforcement body, and is arranged in sequence along the direction of penetrating into the soil; The construction method of the shield end reinforcement structure is: The end reinforcement body is constructed by a combination of three-axis mixing piles and high-pressure jet grouting piles. The strong reinforcement construction method is used for the soil layer 4m above the tunnel top and 1m below the bottom of the caisson blade. The strong reinforcement strength is controlled at 1-1.8Mpa, and the permeability coefficient is not greater than 1.2*10 -7 cm / s; while the disturbed soil within the reinforcement range adopts weak reinforcement construction method; A high-pressure jet grouting method is used to construct and form the retaining wall 0.5m in front of the tunnel entrance; The water-stop curtain wall is constructed by using cement mixing pile TRD method; The lining wall is constructed by cement mixing pile TRD method, and the lining wall is embedded with steel; before the shield starts / receives, the steel is removed; After the main structure is constructed, the gap between the lining wall and the water-stop curtain wall is filled with the triple-tube high-pressure rotary jet pile method to form the caulking reinforcement layer; and the forming thickness of the caulking reinforcement layer is not less than 50 cm.

2. The shield end reinforcement structure construction method according to claim 1 is characterized in that: The reinforcement range of the end reinforcement body is 3m on both sides of the tunnel structure, 3m at the bottom, and 8m at the top, and the longitudinal direction is not less than the length of the shield machine head.

3. The shield end reinforcement structure construction method according to claim 2 is characterized in that: During the strong reinforcement construction stage of the end reinforcement body, a three-axis mixing pile method with a diameter of Φ500-580mm and a close-packed bite of 100-120mm is adopted, and the cement content is controlled at 18-20%; during the weak reinforcement construction stage of the end reinforcement body, a high-pressure rotary jet pile method is adopted, and the cement content is controlled at 12-14%.

4. The shield end reinforcement structure construction method according to claim 1 is characterized in that: During the construction and forming stage of the retaining wall, a high-pressure rotary jet pile method of Φ600-650mm and closely spaced 150-180mm is adopted.

5. The shield end reinforcement structure construction method according to claim 1 is characterized in that: After the vertical shaft sinks and the foundation stabilizes, the end reinforcement body is constructed and formed.

6. The shield end reinforcement structure construction method according to claim 1 is characterized in that: During the construction and forming stage of the inner lining wall, the outer dimensions of the steel section are 700*300*24, and the cement content is controlled at 26-30%.

7. The shield end reinforcement structure construction method according to claim 6 is characterized in that: During the solidification of the retaining wall, a Q235 steel ring is implanted, and fixing screw holes are reserved on the steel ring. The sealing rubber plate and the portal flap are connected to the steel ring by means of bolts.

8. The shield end reinforcement structure construction method according to claim 6 is characterized in that: Before the shield machine is started, the integrity and water-stopping effect of the portal area of ​​the retaining wall are verified; for the portal area, a plurality of evenly distributed horizontal detection holes are drilled on the retaining wall.

9. The shield end reinforcement structure construction method according to claim 1 is characterized in that: During the construction and forming stage of the water-stop curtain wall, the cement content is controlled at 28-30%.

10. The shield end reinforcement structure construction method according to claim 1 is characterized in that: A drainage well is provided within the end reinforcement body; the drainage well does not penetrate the end reinforcement body.

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