A method for constructing underground cavern lining through existing waste piles

Abstract

The present invention relates to the technical field of lining with building materials, and discloses a method for constructing an underground cavern lining that passes through existing waste piles. The method first performs grouting around the waste piles to form a pile-holding tube, and then integrates the waste piles with a portion of the lining grid into a ring structure that supports the underground cavern according to the different positions of the waste piles. This not only ensures that the ground at the waste pile positions will not sink, but also enables the lining at the positions where the waste piles interfere to form a ring to resist the formation pressure. After the first lining construction is completed, the portion of the waste piles located in the underground cavern is removed. At this time, due to the grip of the pile-holding tube and the support of the first lining, the waste piles will not sink after being broken, and the lining portion that does not form a ring due to the removal of the waste piles will not affect the support effect, so that the portion that does not form a ring in the first lining can be easily supplemented and the construction of the second lining can continue. The above content ensures that the lining is smoothly constructed without causing settlement.

Description

Technical Field

[0001] The invention relates to the technical field of lining with building materials, in particular to an underground cavern lining construction method passing through existing waste piles. Background Art

[0002] With the continuous advancement of urbanization, more and more buildings will encounter the problem of previous construction traces in the stratum that affect construction during construction. Among them, the most common problem is the presence of waste piles in the stratum.

[0003] Waste piles are piles that are no longer in use. Many construction processes will leave waste piles in the ground. The most typical example is the rows of piles around the foundation pit. These piles are used to prevent the side walls of the foundation pit from collapsing during construction. After the construction is completed, they no longer play a role and are left in the ground.

[0004] Such waste piles left in the ground usually do not have a significant impact on subsequent ground construction. For example, the waste piles left in the foundation pit of a building will slightly hinder the excavation of the foundation pit of the new building when the building is demolished and a new building is built, but it can be easily solved by pulling out the piles / digging them out and demolishing them.

[0005] However, the impact of waste piles on underground tunnel construction is difficult to overcome, and the impact on shallow buried tunnel construction is the most serious. The reason for underground tunnel construction is that the buildings on the ground still need to be used. This means that waste piles cannot be handled by pulling out / digging them out and demolishing them. In this case, there is currently no relevant experience to follow on how to deal with waste piles that affect construction.

[0006] Taking the air duct of Beitaipingzhuang Station of Beijing Subway Line 19 involved in this application as an example, during the excavation process, it encountered waste piles from a nearby underground garage, and the waste piles were directly inserted into the air duct, affecting the lining construction. Because there are buildings on the ground, the piles cannot be pulled out or dug out. The initial treatment plan was to chisel out the part of the waste piles located in the air duct underground, but after this operation, an unexpected situation occurred: the ground at the location of the waste piles had settled. According to the prior assumptions of the technicians, the combination of the waste piles and the stratum should be firm, and no settlement would be caused even after being cut off, because as friction piles, they are tightly combined with the stratum during construction, and as the stratum is compacted over time, the combination will be more firm. However, the subsequent detection results of the stratum radar showed that the combination of the waste piles and the stratum was not firm, and they sank after being interrupted, resulting in ground settlement. This method of chiseling out the part of the waste piles located in the air duct is not feasible. Summary of the invention

[0007] The invention provides an underground cavern lining construction method passing through existing waste piles.

[0008] The technical problem to be solved is that when the lining of a dark-dug underground cavern interferes with the waste piles in the stratum, the piles cannot be pulled out or dug out.

[0009] In order to solve the above technical problems, the present invention adopts the following technical solutions: a method for constructing underground cavern lining that passes through existing waste piles, which is used for constructing the lining of a dark-excavated underground cavern that interferes with the waste piles in the stratum, wherein the inner space of the primary lining of the underground cavern is recorded as a lining inner space, and among the waste piles that interfere with the underground cavern, the waste pile segments that invade the first lining inner space and overlap with the primary lining are recorded as semi-invasion limit piles, and the waste pile segments that invade the first lining inner space and do not overlap with the primary lining are recorded as fully invading limit piles, and the construction method comprises the following steps:

[0010] Step 1: Grouting is performed around the waste piles to reinforce them, and a cylindrical pile holding tube is formed around the waste piles to hold the waste piles and prevent them from settling;

[0011] Step 2: excavate the underground cavern and record the semi-limited piles and fully-limited piles exposed during the excavation process;

[0012] Step 3: Install the primary lining grille. Each grille is constructed in different ways according to the interference conditions:

[0013] Working condition 1: If a grid has no interference with the semi-limit pile and the full-limit pile, the grid is directly installed and made into a ring;

[0014] Working condition 2: If there is interference between a grille and a semi-intrusion pile, and the semi-intrusion pile completely occupies the installation position of a side wall of the grille, then the side wall of the grille that is occupied by the installation position is removed, and the remaining part is fixed on the semi-intrusion pile, so that the remaining part and the semi-intrusion pile form a ring together;

[0015] Working condition 3: If there is interference between a grille and a semi-intrusion pile, and the interfering semi-intrusion pile part occupies the installation position of a side wall of the grille, the interfering part on the semi-intrusion pile is chiseled out and then the grille is installed to form a ring;

[0016] Working condition 4: If a grille interferes with the full intrusion limit pile, remove the smaller part of the two parts of the grille located on the left and right sides of the full intrusion limit pile, and fix the larger part on the full intrusion limit pile so that the larger part and the full intrusion limit pile form a ring together;

[0017] Step 4: spray concrete onto the grid anchor to form a primary lining;

[0018] Step 5: Remove the waste piles in working conditions 2 and 4 that are located in the space inside the liner, and then replace the grid removed in working condition 4, so that the replaced grid forms a ring with the grid installed in working condition 4, and then spray concrete on the replaced grid anchors to connect them with the concrete in step 4;

[0019] Step 6: Construction of secondary lining.

[0020] Furthermore, the construction method also includes step seven: after the construction is completed, the stratum above the underground cavern is scanned with a stratum radar. If there is an abnormally loose area in the stratum, grouting is performed in the abnormally loose area, and grouting is stopped when grouting emerges from the ground or the settlement of the surface of the abnormally loose area is restored.

[0021] Furthermore, in step 1, if the stratum where the waste pile is located is a loose layer, the wall thickness of the pile holding tube shall not be less than three times the diameter of the waste pile.

[0022] Furthermore, in step one, a formation radar is used to find waste piles, and a deep hole grouting method is used to form a pile holding tube.

[0023] Furthermore, after the grille of step three is installed, the arch foot is reinforced with locking anchor rods.

[0024] Furthermore, the support spacing of the grid of the primary lining is not greater than 600 mm.

[0025] Furthermore, in working conditions 2 and 4, the main reinforcement of the grid is welded to the main reinforcement of the semi-limit pile and the full-limit pile respectively by bar welding, and the steel protection layer of the semi-limit pile and the full-limit pile is chiseled off before welding.

[0026] Furthermore, in step five, a portion of the fully intrusion-limited pile located in a liner space is removed by static cutting.

[0027] Compared with the prior art, the underground cavern lining construction method of the present invention that passes through existing waste piles has the following beneficial effects:

[0028] In the present invention, grouting is first performed around the waste piles to form a pile-holding tube, and then, depending on the location of the waste piles, the waste piles are integrated with a portion of the lining grid to form a ring structure that supports the underground cavern. This not only ensures that the ground at the location of the waste piles will not sink (the waste piles have not been broken at this time), but also enables the lining at the location where the waste piles interfere to form a ring to resist the formation pressure. After the construction of the primary lining is completed, the portion of the waste piles located in the underground cavern is removed. Due to the grip of the pile-holding tube and the support of the primary lining, the waste piles will not sink, and the non-ringed lining portion due to the removal of the waste piles will not affect the support effect (because these non-ringed linings are connected to the adjacent ringed linings), so that the non-ringed portion of the primary lining can be easily filled and the secondary lining can continue to be constructed. The above content ensures that the lining is smoothly constructed without causing settlement. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a schematic diagram of the arrangement of waste piles;

[0030] Figure 2 This is a schematic diagram of the connection between the primary lining and the abandoned piles under working condition 2. In the figure, the part where the primary lining and the semi-limit piles interfere with each other is not constructed, but the primary lining between the semi-limit piles is constructed normally.

[0031] Figure 3 This is a schematic diagram of the connection between the primary lining and the waste piles under working condition 3;

[0032] Figure 4 This is a schematic diagram of the connection between the primary lining and the abandoned piles under working condition 4. In the figure, the primary lining on the left side of the full-limit pile is only constructed between two adjacent piles, and the primary lining is not constructed on the left side of the section where the full-limit pile is located;

[0033] In the figure, 1-primary lining, 2-space inside a lining, 31-semi-invasion limit piles, 32-full-invasion limit piles, 4-pile holding tube. DETAILED DESCRIPTION

[0034] Taking the air duct of Beitaipingzhuang Station of Beijing Subway Line 19 to which the present invention is applied as an example, a method for constructing an underground cavern lining that passes through existing waste piles is used for constructing a lining of a dark-excavated underground cavern that interferes with waste piles in the stratum. The internal space of the primary lining 1 of the underground cavern is recorded as a lining inner space 2. Figure 1 As shown, among the waste piles interfering with the underground caverns, the waste pile sections that invade the inner space 2 of a lining and overlap with the primary lining 1 are recorded as semi-limited piles 31, and the waste pile sections that invade the inner space 2 of a lining and do not overlap with the primary lining 1 are recorded as fully limited piles 32.

[0035] The semi-confined piles 31 are waste piles overlapping the side walls of the primary lining 1 ; and the fully-confined piles 32 are waste piles inserted from the arch of the primary lining 1 into the underground cavern.

[0036] The construction method includes the following steps:

[0037] Step 1: Grouting is performed around the waste piles to reinforce them, and a cylindrical pile-holding tube 4 is formed around the waste piles to hold the waste piles and prevent them from sinking. The pile-holding tube 4 formed in this step mainly plays a role in step 5 to prevent the broken waste piles from sinking, but in step 3, there are various chiseling treatments on the waste piles, which will disturb the strata and cause the risk of ground settlement. Therefore, the pile-holding tube 4 is formed by grouting here, instead of pulling the waste piles to prevent them from sinking. During the grouting process, the soil around the waste piles is consolidated, and the strata will not be disturbed during the chiseling of the waste piles.

[0038] Step 2: excavate the underground cavern and record the semi-confined piles 31 and fully-confined piles 32 exposed during the excavation process; thus adopting different treatment measures for different waste piles.

[0039] Step 3: Install the grille of primary lining 1. Each grille is constructed in different ways according to the interference conditions:

[0040] The grille includes an arch frame and a steel structure between the arch frames (which may be a steel mesh, steel bars, screws, or steel plates). Each grille includes an arch frame and a steel structure between the next arch frame adjacent to it. There are two types of arch frames, one is an I-beam arch frame and the other is a steel bar arch frame. In this embodiment, a steel bar arch frame is used.

[0041] Working condition 1: If a grid has no interference with the semi-limit pile 31 and the full-limit pile 32, the grid is directly installed and formed into a ring;

[0042] The installation of this part of the grille is free from interference, and the installation process is completely consistent with the installation of conventional grilles. Here, the width of each grille (i.e., the support spacing) is adjusted as much as possible to ensure that there is at least one grille without interference between two adjacent waste piles, so that after the demolition in step 5 is completed, there are as many ring structures as possible in the primary lining 1. In this embodiment, the support spacing of the grille of the primary lining 1 is not greater than 600 mm, which is less than the clear distance of the waste piles.

[0043] like Figure 2 As shown, working condition 2: if there is interference between a grille and a semi-invasion limiting pile 31, and the semi-invasion limiting pile 31 that interferes completely occupies the installation position of a side wall of the grille, then the side wall of the grille that occupies the installation position is removed, and the remaining part is fixed on the semi-invasion limiting pile 31, so that the remaining part and the semi-invasion limiting pile 31 form a ring together;

[0044] The strength of the waste piles is greater than that of the primary lining 1, so when the location is appropriate, the waste piles can be used as part of the primary lining 1.

[0045] like Figure 3 As shown, working condition 3: if there is interference between a grille and a semi-invasion limiting pile 31, and the semi-invasion limiting pile 31 that interferes partially occupies the installation position of a side wall of the grille, the grille is installed after the interfering part on the semi-invasion limiting pile 31 is chiseled out to form a ring;

[0046] The waste piles here are not on the same ring surface as the arch of the grille, but are offset a little. Even if they are connected to the grille, they cannot effectively resist the ground pressure. Therefore, it is necessary to carve out a space on the top to install the grille and ensure that the ring is formed.

[0047] like Figure 4 As shown, working condition 4: if a grille interferes with the full intrusion limit pile 32, the smaller part of the two parts of the grille located on the left and right sides of the full intrusion limit pile 32 is removed, and the larger part is fixed on the full intrusion limit pile 32, so that the larger part and the full intrusion limit pile 32 form a ring together;

[0048] Here, the waste piles are blocking the middle of the lining. If they are not interrupted, the lining cannot be made into a ring. However, if they are interrupted rashly, there is a risk of settlement. Therefore, it is simply used to resist the bottom pressure. After all, the waste piles will always lean towards one side of the underground cavern. This allows most of the lining to form a ring, and the small part can rely on the lining of the adjacent frame and the locking anchor rod to ensure stability.

[0049] Step 4: spray concrete onto the grid anchor to form a primary lining 1;

[0050] Step 5: Remove the waste piles in working conditions 2 and 4 located in the first liner space 2, and then fill in the grid removed in working condition 4, so that the filled grid and the grid installed in working condition 4 form a ring, and then spray concrete on the filled grid anchor to connect it with the concrete in step 4;

[0051] Here, it is not necessary to interrupt the waste piles in working condition 2, but it is necessary to interrupt the waste piles in working condition 4. Note that when removing the waste piles in working condition 4, it is necessary to ensure that the connection between the waste piles and the primary lining 1 is not disconnected.

[0052] Step 6: Construction of secondary lining.

[0053] The construction method also includes step seven: after the construction is completed, the stratum above the underground cavern is scanned with a stratum radar. If there is an abnormally loose area in the stratum, grouting is performed in the abnormally loose area, and the grouting is stopped when grouting emerges from the ground or the settlement of the surface of the abnormally loose area is restored.

[0054] This is not necessary, but a safety measure, because there is no precedent for the construction method in the present invention. Its safety is theoretically no problem, but there are not enough samples. In this embodiment, after construction, the formation radar was used to detect and no loose abnormal areas were found. However, even if abnormal situations occur, treatment measures have been prepared and have been tested and verified.

[0055] In step 1, if the stratum where the waste pile is located is a loose layer, the wall thickness of the pile holding tube 4 is not less than three times the diameter of the waste pile.

[0056] If the stratum is soft, even with the pile gripping tube 4, it is easy to make the pile gripping tube 4 and the waste pile sink together, so it is necessary to make the soil in a larger range become the pile gripping tube 4. If the stratum is firm, then fill the fertilizer groove of the waste pile and expand it slightly.

[0057] In step 1, the formation radar is used to find the waste piles, and the pile holding tube 4 is formed by deep hole grouting.

[0058] After the grille installation in step three is completed, the arch foot is reinforced with locking anchor rods.

[0059] In working conditions 2 and 4, the main bars of the grille are welded to the main bars of the semi-limit pile 31 and the full-limit pile 32 respectively. The welding method is bar welding. Before welding, the steel bar protective layer of the semi-limit pile 31 and the full-limit pile 32 is chiseled off. The four longitudinal bars in the steel arch are the main bars of the grille, which can be firmly connected to the main bars of the waste pile. Then, concrete spraying can ensure that the primary lining 1 is effectively connected to the waste pile. Of course, if an I-beam arch is used, it can also be welded to the main bars of the waste pile, but it is relatively difficult.

[0060] In step 5, the portion of the fully intrusion pile 32 located in the first lining space 2 is removed by static cutting. Static cutting has little disturbance and avoids separation of the waste pile from the primary lining 1.

[0061] The embodiments described above are merely descriptions of preferred implementation modes of the present invention and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for constructing an underground cavern lining through existing waste piles, which is used for constructing a lining of a dark-excavated underground cavern that interferes with waste piles in the stratum, wherein the inner space of the primary lining (1) of the underground cavern is recorded as a lining inner space (2), and among the waste piles that interfere with the underground cavern, the waste pile segments that invade the lining inner space (2) and overlap with the primary lining (1) are recorded as semi-invasion limit piles (31), and the waste pile segments that invade the lining inner space (2) and do not overlap with the primary lining (1) are recorded as fully-invasion limit piles (32), characterized in that: The construction method comprises the following steps: Step 1: Grouting is performed around the waste pile to reinforce the waste pile, and a cylindrical pile holding tube (4) is formed around the waste pile to hold the waste pile and prevent it from settling; Step 2: excavating the underground cavern and recording the semi-intrusion limit piles (31) and the fully intrusion limit piles (32) exposed during the excavation process; Step 3: Install the grille of the primary lining (1). Each grille is constructed in different ways according to the interference conditions: Working condition 1: If a grid has no interference with the semi-limit pile (31) and the full-limit pile (32), the grid is directly installed and formed into a ring; Working condition 2: if there is interference between a grille and a semi-intrusion limiting pile (31), and the semi-intrusion limiting pile (31) that interferes completely occupies the installation position of a side wall of the grille, then the side wall of the grille that occupies the installation position is removed, and the remaining part is fixed on the semi-intrusion limiting pile (31), so that the remaining part and the semi-intrusion limiting pile (31) form a ring together; Working condition 3: if there is interference between a grille and a semi-invasion limiting pile (31), and the semi-invasion limiting pile (31) that interferes partially occupies the installation position of a side wall of the grille, the grille is installed after the interfering portion on the semi-invasion limiting pile (31) is chiseled out so as to form a ring; Working condition 4: if a grille interferes with the full intrusion limit pile (32), the smaller part of the two parts of the grille located on the left and right sides of the full intrusion limit pile (32) is removed, and the larger part is fixed on the full intrusion limit pile (32) so that the larger part and the full intrusion limit pile (32) form a ring together; Step 4: spraying concrete onto the grid anchor to form a primary lining (1); Step 5: remove the waste piles in working conditions 2 and 4 located in the space (2) in the lining, and then replace the grid removed in working condition 4, so that the replaced grid forms a ring with the grid installed in working condition 4, and then spray concrete on the replaced grid anchor to connect it with the concrete in step 4; Step 6: Construction of secondary lining; Step 7: After the construction is completed, use the formation radar to scan the stratum above the underground cavern. If there are loose abnormal areas in the stratum, grouting is carried out in the loose abnormal areas. The grouting is stopped when grouting appears on the ground or the settlement of the surface of the loose abnormal area is restored.

2. The method for constructing an underground cavern lining through existing waste piles according to claim 1, characterized in that: In step 1, if the stratum where the waste pile is located is a loose layer, the wall thickness of the pile holding tube (4) shall not be less than three times the diameter of the waste pile.

3. The method for constructing an underground cavern lining through existing waste piles according to claim 1, characterized in that: In step 1, the abandoned piles are found by using a formation radar, and a pile holding tube (4) is formed by deep hole grouting.

4. The method for constructing an underground cavern lining through existing waste piles according to claim 1, characterized in that: After the grille installation in step three is completed, the arch foot is reinforced with locking anchor rods.

5. The method for constructing an underground cavern lining through existing waste piles according to claim 1, characterized in that: The support spacing of the grid of the primary lining (1) shall not exceed 600mm.

6. The method for constructing an underground cavern lining through existing waste piles according to claim 1, characterized in that: In working conditions 2 and 4, the main reinforcement of the grid is welded to the main reinforcement of the semi-invasion limit pile (31) and the full-invasion limit pile (32) respectively, and the welding method is bar welding. Before welding, the steel bar protective layer of the semi-invasion limit pile (31) and the full-invasion limit pile (32) is chiseled off.

7. The method for constructing an underground cavern lining through existing waste piles according to claim 1, characterized in that: In step five, a static cutting method is used to cut off the portion of the fully intrusion-limited pile (32) located in a lining space (2).

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