A method of construction of an underground structure

Abstract

The application discloses a construction method of underground structure, comprising the following steps: dividing into several caissons, using caisson method to construct and pre-burying freezing device; using U-shaped MJS pile to construct the joint position of the well wall of adjacent caissons; constructing the cushion and bottom plate of each caisson; starting the freezing device to freeze and reinforce; cutting the plate thickness part of the well wall of each layer of the cushion from the bottom plate upwards in sequence, binding the steel bars at the cutting position according to the plate reinforcement requirement, pouring the concrete to connect into a whole; then cutting the side wall of the joint position of the adjacent caissons in sequence, and connecting into a whole. The caisson method is used for excavation to maintain the water level in the caisson to avoid the phenomenon of soil gushing and sand flowing, the U-shaped MJS and freezing are used for reinforcing at the joint position of the adjacent caissons, the water stopping effect is guaranteed, each layer of plate is constructed from bottom to top, and the well wall of the plate thickness range between the caissons is removed, then the construction is carried out at the joint position of the side wall of the adjacent caissons, and the rigidity and stability of the structure in the construction process are guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building construction, in particular to a construction method of underground structure. BACKGROUND

[0002] At present, the commonly used method for underground structure construction is open cut method. When the open cut method is used for construction, if the bottom of the enclosure structure is in soft stratum, the underground water can still flow into the construction range of the underground structure through the gap of the soil below the enclosure structure and bypass the bottom of the enclosure structure. In the construction process, piping can easily occur at the bottom of the foundation pit, causing water and sand to gush, which brings great safety risk to the excavation construction. SUMMARY

[0003] The present application aims to at least solve one of the problems in the prior art. To this end, the present application provides a construction method of underground structure, which can ensure the water stopping effect during the construction of the structure at the connection position of the sinking well.

[0004] The construction method of underground structure according to the first aspect of the present application comprises:

[0005] The underground structure is equally divided into several sinking wells, and the sinking well method is used for construction. The freezing device is pre-buried when the sinking well is constructed. After the sinking well is sunk to the designed elevation position, the bottom is sealed with underwater concrete;

[0006] After the underwater concrete of the sealed bottom reaches the designed strength, the U-shaped MJS pile is constructed at the connection position of the well walls of the adjacent sinking wells;

[0007] After the MJS pile reaches the designed strength, the water in the sinking well is pumped out, and the cushion and the bottom plate of each sinking well are constructed;

[0008] The freezing device at the connection position of the well walls of the adjacent sinking wells is opened, and the soil in the gap between the adjacent sinking wells is frozen and reinforced;

[0009] The well wall at the connection position of the adjacent sinking wells is cut from the bottom plate upwards in sequence, and the cut part is bound with steel bars and poured with concrete according to the requirements of the plate reinforcement. Each bottom plate and each layer plate are connected into a whole;

[0010] Then, the support between the adjacent plates is cut from top to bottom in sequence, and the gap left after the well wall is removed is constructed. The side wall at the connection position of the adjacent sinking wells is constructed, and the two side walls are connected into a whole;

[0011] The freezing device is closed to thaw, and the construction is completed.

[0012] According to the construction method of the underground structure of the embodiment of the first aspect of the present invention, there are at least the following beneficial effects: each caisson is excavated using the caisson method, and the water level in the well is maintained during the excavation process to avoid soil gushing and sand flow. MJS and freezing are used to perform "U-shaped" reinforcement at the connection position of adjacent caissons to ensure the water-stopping effect. After MJS and freezing reinforcement, each layer of plates is constructed from bottom to top and the well walls within the plate thickness range between the caissons are removed, and the plates of each caisson are connected into a whole, thereby ensuring the rigidity and stability of the structure during construction. After the construction of each layer of plates, the well walls are removed from top to bottom. Since there is a gap between the two caissons, it is also necessary to construct the connection position of the side walls of adjacent caissons to connect the side walls on both sides into a whole. Finally, the side walls of each layer are connected into a whole and meet the strength requirements before they can be thawed to ensure the water-stopping effect of the structure during construction at the connection position of the caissons.

[0013] According to the construction method of the underground structure described in the embodiment of the first aspect of the present invention, after the underground structure is divided into several caissons, pull-out piles are first installed, and diagonal braces are set at the corresponding elevations. After excavation to the design elevation, the underwater concrete poured on the base is connected to the pull-out piles, and refrigeration devices are pre-embedded in the well walls on both sides of the fitting surface of adjacent caissons.

[0014] According to the construction method of the underground structure described in the embodiment of the first aspect of the present invention, after the underground structure is equally divided into several caissons with similar length and width, the construction is divided into two phases, first constructing the first phase caisson, and then constructing the second phase caisson, wherein the caissons are numbered in sequence, the first phase caissons are the caissons with odd numbers, and the second phase caissons are the caissons with even numbers.

[0015] According to the construction method of the underground structure described in the embodiment of the first aspect of the present invention, the earth excavation method is undrained excavation to ensure the balance of water and soil pressure inside and outside the well, and the caisson is sunk by excavating in sections in the height direction and extending the well wall.

[0016] According to the construction method of the underground structure described in the embodiment of the first aspect of the present invention, after the caisson sinks to the designed base elevation, the floating mud at the bottom of the well is first removed, the bottom of the pot is trimmed, a gravel cushion layer is laid, and the bottom is sealed with C20 underwater concrete.

[0017] According to the construction method of underground structures described in the embodiment of the first aspect of the present invention, interlocking MJS piles are installed at the junction of the walls of adjacent caissons, and the solid pile part of the MJS pile is from the bottom elevation of the foundation pit to a preset depth below the blade foot.

[0018] According to the construction method of the underground structure described in the embodiment of the first aspect of the present invention, the construction range of the MJS pile is U-shaped in cross section.

[0019] The construction method of the underground structure according to the first aspect of the present application cuts the well wall at the position where the adjacent well walls of the thickness part of each layer of the floor meet, from the bottom floor to the top, in three parts for each layer of the well wall, first constructs the left and right parts, then constructs the middle part, and retains the support system when constructing each layer of the floor.

[0020] The construction method of the underground structure according to the first aspect of the present application constructs the scaffold in layers after the strength of the bottom floor reaches the requirement, and then cuts the well wall at the position where the adjacent well walls of the thickness part of each layer of the floor meet.

[0021] The construction method of the underground structure according to the first aspect of the present application removes the scaffold in layers when cutting the support between the adjacent floors and constructing the side wall from the top to the bottom.

[0022] Additional aspects and advantages of the present application will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following and / or can be learned by practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0023] The present application is further described below in conjunction with the accompanying drawings and examples;

[0024] Figure 1 The schematic diagram of the construction of the uplift pile in the embodiment of the present application;

[0025] Figure 2 The schematic diagram of the construction of the first-stage well by the well sinking method in the embodiment of the present application;

[0026] Figure 3 The schematic diagram of the bottom sealing of the first-stage well by the underwater concrete in the embodiment of the present application;

[0027] Figure 4 The schematic diagram of the construction of the second-stage well by the well sinking method in the embodiment of the present application;

[0028] Figure 5 The schematic diagram of the bottom sealing of the second-stage well by the underwater concrete in the embodiment of the present application;

[0029] Figure 6 The schematic diagram of the construction of the MJS pile in the embodiment of the present application;

[0030] Figure 7 The schematic diagram of the construction of the cushion and the floor of each well after the drainage in the embodiment of the present application;

[0031] Figure 8 The schematic diagram of the cutting of the well wall of the thickness part of the floor in the embodiment of the present application;

[0032] Figure 9 The schematic diagram of the connection of the floors into a whole in the embodiment of the present application;

[0033] Figure 10 A schematic view of the well wall in which the plate thickness part of the layer plate is cut off in an embodiment of the present application;

[0034] Figure 11 A schematic view of the layer plate being integrated in an embodiment of the present application;

[0035] Figure 12 A schematic view of the side wall being integrated in an embodiment of the present application;

[0036] Figure 13 A schematic view of the construction being completed in an embodiment of the present application. DETAILED DESCRIPTION

[0037] Embodiments of the present application are described below in detail, examples of which are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, only for explaining the present application, and cannot be understood as a limitation to the present application.

[0038] In the description of the present application, it is understood that the orientation description, such as the orientation or position relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or position relationship shown in the drawings, only for the convenience of describing the present application and simplifying the description, and is not intended to indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation to the present application.

[0039] In the description of the present application, the meaning of several is one or more, the meaning of multiple is at least two, greater than, less than, more than, etc. is understood as not including the number, above, below, etc. is understood as including the number. If it is described as first, second, only for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or the sequence of indicated technical features.

[0040] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be understood in a broad sense, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0041] Reference Figures 1 to 13 , the construction method of the underground structure of the first aspect embodiment of the present application, especially a construction method of an underground structure with a soft ground layer and prone to water and sand gushing, the construction method of the underground structure comprises the following steps:

[0042] An underground structure is divided into several caissons, which are constructed using the caisson method. A refrigeration device 4 is pre-buried during the caisson construction. After the caisson is sunk to the designed elevation, the bottom is sealed with underwater concrete 3.

[0043] When the bottom seal underwater concrete 3 reaches the design strength, interlocking U-shaped MJS piles 6 are installed at the junction of the walls of adjacent caissons;

[0044] After the MJS piles 6 have reached their designed strength, the water in the caissons is drained and the cushions and bottom plates 7 of each caisson are constructed;

[0045] Open the freezing device 4 at the junction of the walls of adjacent caissons to freeze and reinforce the soil in the gap between the adjacent caissons. The next step of construction can only be carried out after the thickness and temperature of the frozen body meet the requirements;

[0046] From the bottom plate 7 upwards, the thick portion of the layer plates 8 of each cushion layer is sequentially removed at the location where adjacent caissons meet. The removed portions are reinforced with steel bars and concrete is poured according to the plate reinforcement requirements. Each bottom plate 7 and each layer plate 8 is connected into a whole. Next, the supports between adjacent plates are sequentially removed from top to bottom. The gaps left after the removal of the wall are constructed, and the side walls at the location where adjacent caissons meet are constructed, and the side walls on both sides are connected into a whole.

[0047] Close the freezing device 4 to thaw and complete the construction.

[0048] Specifically, refer to Figures 8 to 11 The well wall where adjacent caissons meet after the thickness of the bottom plate 7 is cut away is the first cutaway portion 9, and the well wall where adjacent caissons meet after the thickness of the layer plate 87 is cut away is the second cutaway portion 11. The whole formed by connecting the bottom plates 7 is the first integral portion 10, and the whole formed by connecting the layer plates 8 is the second integral portion 13. Preferably, the construction methods of the layer plates 8 and the top plate are the same and will not be further described here.

[0049] Reference Figures 1 to 13 The construction method of the underground structure of the embodiment of the first aspect of the present application divides the well into several caissons, and each caisson is excavated without drainage using the caisson method. During the excavation process, the water level in the well is maintained to prevent soil gushing and sand flow. MJS and freezing are used to perform "U-shaped" reinforcement at the connection position of adjacent caissons to ensure the water-stopping effect. After MJS and freezing reinforcement, each layer of plates 8 is constructed from bottom to top and the well walls within the plate thickness range between the caissons are removed, and the plates of each caisson are connected into a whole, ensuring the rigidity and stability of the structure during construction. After the construction of each layer of plates 8, the well walls are removed from top to bottom. Since there is a gap between the two caissons, it is also necessary to construct the connection position of the side walls of adjacent caissons to connect the side walls on both sides into a whole. Finally, the side walls of each layer are connected into a whole and meet the strength requirements before they can be thawed to ensure the water-stopping effect of the structure during construction at the caisson connection position.

[0050] In some embodiments of the present application, after the caisson is equally divided into several caissons, the uplift pile 1 is first constructed, and the inclined brace is arranged at the corresponding elevation, wherein the support is arranged as the inclined brace at the corresponding elevation of the original station support, the earth excavation method is undrained excavation, the balance of water and soil pressure inside and outside the caisson is ensured, the caisson is sunk through the segmented excavation in the height direction, the caisson wall is lengthened, and after the excavation reaches the design elevation, the underwater concrete 3 poured on the base is connected with the uplift pile 1, and the cold freezing device 4 is pre-buried in the caisson wall positions on both sides of the abutting surface of adjacent caissons. Specifically, the underwater concrete 3 poured on the base is used to resist the external water and soil pressure, and is connected with the uplift pile 1 to prevent the structure from floating up. In addition, the caisson wall on both sides of the abutting surface of adjacent caissons needs to be pre-buried with U-shaped freezing pipes.

[0051] In some embodiments of the present application, after the underground structure is equally divided into several caissons with similar length and width, the construction is divided into two stages, the first stage caisson 2 is constructed first, and then the second stage caisson 5 is constructed, wherein each caisson is sequentially numbered, the first stage caisson 2 is the caisson with odd number, and the second stage caisson 5 is the caisson with even number. After the caisson is sunk to the design base elevation, the floating mud at the bottom of the caisson is first removed, the bottom of the caisson is trimmed, the gravel cushion layer is paved, and the underwater concrete 3 with C20 is used for bottom sealing.

[0052] In some embodiments of the present application, the MJS pile 6 is constructed at the abutting position of the caisson wall of adjacent caissons. The actual pile part of the MJS pile 6 is at a preset depth from the bottom elevation of the foundation pit to below the blade foot. Specifically, the actual pile part of the MJS pile 6 at the abutting position of the caisson wall of adjacent caissons is at a certain depth from the bottom elevation of the foundation pit to below the blade foot, and the actual pile parts of the two outermost MJS piles 6 are at a certain depth from the ground to below the blade foot with the middle MJS pile 6. The construction range of the MJS pile 6 is in the shape of U on the transverse section.

[0053] In some embodiments of the present application, when the caisson wall at the abutting position of adjacent caissons is sequentially cut from the bottom plate 7 to the plate thickness part of each layer plate 8, each layer of caisson wall is constructed in three parts, the left and right parts are constructed first, and then the middle part is constructed, and the support system is retained during the construction of each layer plate 8. After the strength of the bottom plate 7 meets the requirements, the scaffolding 12 is first erected layer by layer, and then the caisson wall at the abutting position of adjacent caissons of the plate thickness part of each layer plate 8 is cut layer by layer. When the adjacent plate interlayer support and the side wall are sequentially cut from top to bottom, the scaffolding 12 is dismantled layer by layer.

[0054] Specifically, referring to Figure 12 wherein the sequential cutting of the adjacent plate interlayer support and the side wall from top to bottom can be defined as the construction of the structure 14, and each caisson is connected into a whole through the construction of each construction structure 14 of each caisson.

[0055] More specifically, in the construction embodiment, the underground structure is equally divided into five vertical shafts in the length direction, which are No. 1, 2, 3, 4 and 5 shafts in sequence. The following describes two parts of foundation pit excavation stage and main structure construction stage.

[0056] Foundation pit excavation stage:

[0057] 1) Construct pull-out pile 1.

[0058] 2) Construct the first phase of caissons (1, 3, and 5). Once completed and reaching the required strength, excavate the earth and remove the underlying timbers to allow the caissons to sink. Excavation is performed using a non-draining method. During the sinking process, the water level inside the caisson must be maintained 1-2 meters above the water level outside. During the sinking process, the sinking speed must be adjusted. When the caisson is 0.2 meters above the ground, the caisson is raised.

[0059] 3) After the caisson sinks to the designed base elevation, first remove the floating mud at the bottom of the well, trim the bottom of the pot, lay a gravel cushion layer, and use C20 underwater concrete 3 to seal the bottom.

[0060] 4) Repeat steps 2) and 3) to complete the construction of the second phase of caisson 5 (caissons 2 and 4).

[0061] 5) Construct MJS piles 6 at the junction of adjacent caisson walls. The solid pile part is from the bottom elevation of the foundation pit to a certain depth below the blade foot, and the solid pile parts of the two outermost MJS piles 6 are from the ground to a certain depth below the blade foot and the middle MJS pile 6. The construction range of the MJS pile 6 is U-shaped in the cross section to ensure the water-stopping effect at the joint position.

[0062] Main structure construction phase:

[0063] 1) Drain the water from the five caissons, then create a cushion layer and install the base plate 7. Activate the freezing devices 4 on the walls of adjacent caissons to freeze and consolidate the soil in the gaps between them. Once the required freezing index is reached, cut away the wall where the adjacent caissons meet, then rebar is tied and concrete is poured in accordance with the reinforcement requirements for the base plate 7, connecting the cutout sections to the base plate 7.

[0064] 2) After the strength of the bottom plate 7 reaches the required level, set up the scaffolding 12, cut off the wall of the adjacent caissons where the thickness of the negative second plate is connected, tie the steel bars and pour the concrete for the cut-off part according to the reinforcement requirements of the negative second layer plate 8, and connect it with the negative second layer plate 8 to form a whole. The wall of the well is constructed in three parts, the left and right parts are constructed first, and then the middle part is constructed.

[0065] 3) Repeat step 2) to construct the negative layer slab 8 and the top slab.

[0066] 4) Cut off the 8 supports between the top plate and the negative first floor plate and the well wall at the junction of adjacent caissons, and construct the side walls at the junction of adjacent caissons to connect the side walls on both sides into a whole.

[0067] 5) Repeat step 4) to construct the second and first basement floors.

[0068] 6) Close the freezing equipment to thaw, complete the construction.

[0069] The method divides the underground structure into several caissons in length direction, adopts caisson method to construct in two periods, uses undrained excavation to ensure the balance of water and soil pressure inside and outside the caisson, uses MJS pile 6 to reinforce and freeze to reinforce the joint position of adjacent caissons to ensure the water stopping effect of the connection construction between the subsequent caissons and the caissons, does not remove the support when constructing each layer plate 8 of the main structure, removes each layer of the well wall and the support from top to bottom after the construction of each layer plate 8, and constructs the side wall at the joint position of adjacent caissons, so that the side wall is connected into a whole, ensures that the structure has sufficient rigidity, and the application is suitable for the case that the bottom of the enclosure structure is located in soft stratum, can avoid the risk of water and sand gushing, and ensures the construction safety.

[0070] The technical features of the above-described embodiments can be combined arbitrarily, and to make the description concise, all possible combinations of the technical features in the above-described embodiments are not described, however, as long as the combinations of the technical features do not exist contradictory, they should be considered as the scope of the present application.

[0071] The embodiments of the present application are described in detail above in combination with the drawings, but the present application is not limited to the above-described embodiments, and various changes can be made within the knowledge of those skilled in the art in the technical field without departing from the purpose of the present application.

Claims

1. A construction method for an underground structure, characterized in that: The following steps are involved: An underground structure is divided into several caissons, which are constructed using the caisson method. A refrigeration device is embedded in the caissons. After the caissons are sunk to the designed elevation, the bottom is sealed with underwater concrete. When the underwater concrete of the bottom seal reaches the designed strength, interlocking U-shaped MJS piles are installed at the junction of the walls of adjacent caissons; After the MJS piles reach the designed strength, drain the water from the caissons and construct the cushions and bottom plates of each caisson; Turn on the freezing device at the junction of the walls of adjacent caissons to freeze and consolidate the soil in the gaps between the adjacent caissons; Cut away the thick portion of the layer plates of each cushion layer from the bottom plate upwards, and cut away the walls of adjacent caissons at the joints. Tie steel bars and pour concrete in the cut-away areas according to the plate reinforcement requirements, and connect the bottom plates and layer plates into a whole. Then, the supports between adjacent slabs are removed from top to bottom, and the gaps left after the well walls are removed are constructed to construct the side walls where adjacent caissons meet, connecting the two side walls into a whole. Turn off the freezer to thaw and complete the construction.

2. The construction method of an underground structure according to claim 1, characterized in that: After being divided into several caissons, anti-pullout piles are first installed. After excavation to the designed elevation, the underwater concrete poured on the base is connected to the anti-pullout piles. Refrigeration devices are pre-embedded in the well walls on both sides of the fitting surface of adjacent caissons.

3. The construction method of an underground structure according to claim 2, characterized in that: After the underground structure is divided into several caissons of similar length and width, the construction is divided into two phases. The first phase caisson is constructed first, and then the second phase caisson is constructed. The caissons are numbered in sequence. The first phase caissons are odd-numbered caissons, and the second phase caissons are even-numbered caissons.

4. The construction method of an underground structure according to claim 2, characterized in that: The earth excavation method is undrained excavation to ensure the balance of water and soil pressure inside and outside the well. The caisson is sunk by excavating in sections in the height direction and extending the well wall.

5. The construction method of an underground structure according to claim 4, characterized in that: After the caisson sinks to the designed base elevation, the floating mud at the bottom of the well is first removed, the bottom of the pot is trimmed, a gravel cushion layer is laid, and the bottom is sealed with C20 underwater concrete.

6. The construction method of an underground structure according to claim 1, characterized in that: Interlocking MJS piles are constructed at the junction of the walls of adjacent caissons. The solid pile part of the MJS pile is from the bottom elevation of the foundation pit to a preset depth below the blade foot.

7. The construction method of an underground structure according to claim 1 or 6, characterized in that: The construction scope of the MJS pile is U-shaped in cross section.

8. The construction method of an underground structure according to claim 7, characterized in that: When the wall of adjacent caissons is cut away from the bottom plate upwards in sequence, each layer of the wall is constructed in three parts, with the left and right parts constructed first and the middle part constructed later. The support system is retained when constructing each layer of the plate.

9. The construction method of an underground structure according to claim 8, characterized in that: After the bottom plate strength reaches the requirement, scaffolding is erected layer by layer, and then the wall of adjacent caissons is cut off layer by layer at the junction of the thick part of the layer plate.

10. The construction method of an underground structure according to claim 9, characterized in that: When cutting off the supports between adjacent boards and constructing the side walls from top to bottom, the scaffolding is removed layer by layer.

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