Underground space cover-excavation top-down construction method and construction device

Abstract

The invention relates to an underground space cover-excavation top-down construction method and device. According to an existing cover-excavation reverse construction method, before a top plate is constructed and earthwork is backfilled, a pile foundation and a steel pipe concrete column need to be constructed firstly, and therefore the opening time of road traffic is affected. The construction method comprises the following steps that the enclosure structure is constructed; a first layer of laminate and a column cap are poured; backfilling earthwork; single-side original soil is excavated, and a side wall is poured; a second layer of laminate and a concrete column are poured; digging out the whole layer of original soil; and pouring the residual side wall. A pile foundation and a steel pipe concrete column do not need to be constructed before earthwork backfilling, so that the earthwork backfilling time node is greatly advanced, road traffic is opened in advance, and the influence on the road traffic is reduced; the supporting performance of original soil on the laminates is utilized, so that the use of brackets is reduced; before the excavation face extends to the column cap, the layer plate is temporarily supported through the supporting column in advance, so that settlement of the layer plate on the upper layer after original soil is excavated is prevented, concrete column construction is facilitated, and the engineering safety is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of engineering construction, in particular to a construction method and device for a cover-excavation top-down method of underground space. BACKGROUND

[0002] The cover-excavation top-down method is usually used in the construction of underground rail projects. The cover-excavation top-down method has the advantages of reducing the impact on road traffic, saving formwork, and being less affected by weather. In the existing cover-excavation top-down method, the enclosing structure, pile foundation and steel pipe concrete column are first constructed, then the top plate is made, the road traffic is opened after backfilling soil on the top plate, and then the soil is excavated from top to bottom under the top plate to construct the middle plate and the bottom plate. In the existing cover-excavation top-down method, the pile foundation and the steel pipe concrete column need to be constructed before the top plate and the backfilling soil, thereby affecting the opening time of the road traffic. SUMMARY

[0003] The purpose of the present application is to provide a construction method and device for a cover-excavation top-down method of underground space to at least solve the problem of slow opening of road traffic in the existing cover-excavation top-down method.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present application is as follows:

[0005] The construction method for the cover-excavation top-down method of underground space comprises the following steps:

[0006] Constructing an enclosing structure;

[0007] Pouring a first layer of a slab and a column cap: excavating soil inside the enclosing structure according to the design elevation of the slab of the first layer and the design position of the concrete column to form a horizontally extending first excavation surface, pouring the slab of the first layer and the column cap above the first excavation surface, pouring the slab of the first layer and the enclosing structure together at the edge, and reserving a soil outlet at the edge of the slab of the first layer;

[0008] Backfilling soil: after the slab of the first layer forms strength, backfilling soil above the slab of the first layer to open the road traffic;

[0009] Excavating and pouring a side wall: according to the design elevation of the slab of the second layer, excavating the original soil on one side of the enclosing structure through the soil outlet to form a horizontally extending second excavation surface and a vertically extending third excavation surface, pouring a side wall on the inner wall of the enclosing structure after the inner wall is exposed, pouring the side wall and the slab of the first layer together at the top side, and continuing to excavate the original soil to the other side of the enclosing structure;

[0010] Pouring the second layer of the slab and the concrete column: when the third excavation surface is close to the column cap, stop excavating, install the support column under the first layer of the slab, the upper end of the support column supports the first layer of the slab, and the lower end supports on the second excavation surface, continue to excavate the original soil to the other side of the column cap, and then stop excavating, pour the second layer of the slab on the second excavation surface, and pour the concrete column under the column cap;

[0011] Excavating the whole layer of the original soil: after the concrete column and the second layer of the slab form strength, remove the support column, the lower end of the support column is buried in the second layer of the slab, continue to excavate the other side of the enclosure, and repeat the steps of pouring the second layer of the slab and the concrete column when the third excavation surface is close to the next column cap until the whole layer of the original soil is excavated.

[0012] Pouring the remaining side wall: continue to pour the remaining side wall on the inner wall of the enclosure.

[0013] Further, when the last layer of the slab is not poured in the steps of pouring the second layer of the slab and the concrete column and excavating the whole layer of the original soil, the earth outlet is reserved on the second layer of the slab, and the column cap of the next layer is poured at the lower end of the concrete column. Repeat the steps of excavating the single side of the original soil and pouring the side wall, pouring the second layer of the slab and the concrete column, excavating the whole layer of the original soil, and pouring the remaining side wall until the last layer is completed.

[0014] Further, the column cap is pre-buried with steel bars, and the lower end of the steel bars extends to the outside of the column cap.

[0015] Further, when pouring the concrete column, first bind the steel bars at the position of the concrete column, connect the upper end of the steel bars of the concrete column with the pre-buried steel bars in the column cap, then install the formwork around the steel bars, pour the concrete in the formwork to shape the concrete column, and remove the formwork after the concrete column forms strength.

[0016] The construction device of the cover-excavation reverse construction method of the underground space, the construction device comprises the support column for temporarily supporting the slab, the support column comprises the telescopic column, the base, the telescopic mechanism, the support head and the moving support mechanism;

[0017] The telescopic column comprises the sleeve and the support rod, the sleeve is detachably arranged at the upper end of the base, the support rod is slidably arranged in the sleeve, and the support head is arranged at the upper end of the support rod;

[0018] The telescopic mechanism is arranged at the connection between the sleeve and the support rod;

[0019] The moving support mechanism is arranged on the side wall of the support rod, and when the support rod is not completely contracted into the sleeve, the moving support mechanism can tightly abut against the ground.

[0020] Further, the lower end of the sleeve is provided with a protruding fixing key.

[0021] Further, the upper end of the base is provided with a slot matched with the fixing key.

[0022] Further, the moving support mechanism comprises a plurality of moving support assemblies symmetrically arranged on the side walls of the support rod, each of the moving support assemblies comprising a side frame rotatably connected to the side wall of the support rod at the top and a plurality of wheels rotatably connected to the side frame at the bottom.

[0023] Further, the telescopic mechanism comprises a battery, a motor, a worm gear, a worm, a driving gear and a rack, the rack being arranged below the side wall of the support rod, the driving gear being arranged at the upper end of the sleeve and engaged with the rack, the worm gear being coaxially arranged on one side of the driving gear, the worm being arranged in cooperation with the worm gear, the motor being arranged on the side wall of the sleeve and connected with the worm, and the battery being arranged between the side frames and located on the side opposite to the rack, the battery being electrically connected with the motor.

[0024] Further, a limiting rod is arranged between the side frames.

[0025] Compared with the prior art, the present application has the following advantages:

[0026] 1. The present application provides a construction method and device for top-down construction of underground space, which does not need to construct pile foundation and steel pipe concrete column before backfilling, so that the time node of backfilling is greatly advanced, thereby the road traffic is opened in advance, and the influence on road traffic is reduced; and the present application uses the supporting property of the original soil on the slab to reduce the use of bracket; the excavation surface extends to the column cap, and the slab is temporarily supported by the supporting column in advance, so as to prevent the slab on the upper layer from sinking after the original soil is removed, thereby facilitating the construction of concrete column and improving the engineering safety.

[0027] 2. The moving support assembly is arranged on the supporting column, so that the supporting column can be moved to the next supporting point to support the slab; when the supporting column supports the slab, the side frame and the wheels are suspended above the slab to be poured, thereby reducing the occupation of underground space; and during the shortening of the telescopic column, the sleeve can be automatically separated from the base, thereby saving labor. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, without paying any creative work, they can also obtain drawings of other embodiments based on these drawings.

[0029] Figure 1 Schematic diagram of the construction of the enclosure structure and the first floor slab of Example 1;

[0030] Figure 2 This is a schematic diagram of the support columns supporting the underground space in Example 1;

[0031] Figure 3 Schematic diagram of the cast floor slab and concrete columns in the underground space of Example 1;

[0032] Figure 4 This is a schematic diagram of the underground space after it is formed in Example 1;

[0033] Figure 5 Schematic diagram of the support columns supporting the second underground space in Example 1;

[0034] Figure 6 Schematic diagram of the cast slab and concrete columns in the underground second floor space of Example 1;

[0035] Figure 7 This is a schematic diagram of the second underground space after it is formed in Example 1;

[0036] Figure 8 is a structural diagram of Example 2;

[0037] Figure 9 yes Figure 8 The structural diagram of the other side;

[0038] Figure 10 is a side view of Example 2;

[0039] Figure 11 is a schematic diagram of the base and sleeve being separated in Example 2;

[0040] The symbols in the figure are:

[0041] 1-Original soil, 2-Enclosure structure, 3-Layer plate, 4-First excavation surface, 5-Groove, 6-Concrete column, 7-Column cap, 8-Excavation opening, 9-Second excavation surface, 10-Third excavation surface, 11-Side wall,

[0042] 12-support column, 121-telescopic column, 1211-sleeve, 1212-support rod,

[0043] 122-base,

[0044] 123 - telescopic mechanism, 1231 - battery, 1232 - motor, 1233 - worm wheel, 1234 - worm, 1235 - rack, 124 - wheel, 125 - frame including side frames, 126 - limit rod, 127 - support head. DETAILED DESCRIPTION

[0045] In order to facilitate the understanding of the present application, a more comprehensive description will be made below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive.

[0046] In the description of the present application, it should be understood that the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying 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 limiting the present application.

[0047] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "setting" should be understood broadly, for example, it can be fixedly connected, set, or It can also be detachably connected, set, or integrally connected, set. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0048] At the same time, in the description of the present application, the terms "first", "second" and the like are only used to distinguish the description and cannot be understood as indicating or implying relative importance. Of course, such objects can be interchanged under appropriate circumstances, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0049] In the description of the present application, it should be understood that in the process of describing the method, a plurality of steps are involved, and it should not be understood as a limitation on the order of the method steps. The technical solutions obtained by changing the order of steps when solving the same technical problem are also within the protection scope of the present application.

[0050] Example 1:

[0051] The present embodiment provides a top-down reverse construction method for underground space. The underground space structure designed in the present embodiment is two layers underground, and the construction method comprises the following steps:

[0052] S1: Construction Envelope

[0053] like Figure 1 As shown, according to the design drawings, lines are laid out on the construction site to locate the position where the retaining structure 2 needs to be constructed. When constructing the retaining structure 2, a hole is first drilled on the ground with a drilling machine, and then a steel cage is placed in the hole, and then concrete is poured into the hole to finally form the retaining structure 2 to improve the stability of the soil.

[0054] S2: Casting of first floor slabs and column caps

[0055] On the inner side of the retaining structure 2, excavate the earth according to the design elevation of the first layer slab 3 and the design position of the concrete column 6 to form a horizontally extending first excavation surface 4. On the first excavation surface 4, dig a groove 5 that is adapted to the column cap 7 according to the design position of the concrete column 6. Lay plywood in the first excavation surface 4 and the groove 5 as a ground formwork. Cast the first layer slab 3 and the column cap 7 above the first excavation surface 4. Specifically, first tie the steel bars on the upper side of the ground formwork, and weld the steel bars at the edge of the ground formwork to the steel bars at the upper end of the retaining structure 2 to provide a The connection strength between the retaining structure 2 and the first-layer slab 3 is improved, and then concrete is poured onto the ground formwork to form an integrated slab 3 and column cap 7. The edge of the first-layer slab 3 is cast together with the retaining structure 2, which further improves the connection strength between the slab 3 and the retaining structure 2, so that the retaining structure 2 can stably support the slab 3. When the original soil 1 on the lower side of the slab 3 is subsequently excavated from the edge of the retaining structure 2, the edge of the slab 3 will not collapse, and an excavation opening 8 is reserved near the edge of the first-layer slab 3.

[0056] Steel bars are embedded in the column cap 7 , and the lower ends of the steel bars extend outside the column cap 7 to enhance the connection reliability between the column cap 7 and the upper end of the concrete column 6 .

[0057] S3: Backfill

[0058] After the first layer of the slab 3 has formed strength, the original soil 1 on the lower side of the slab 3 supports the slab 3, and the soil is backfilled above the first layer of the slab 3 to open the road to traffic.

[0059] In this embodiment, there is no need to construct pile foundations and steel tube concrete columns before this step, so that the backfill time node is greatly advanced and road traffic is opened in advance, thereby reducing the impact on road traffic.

[0060] S4: Excavate the original soil on one side and cast the side wall

[0061] According to the design elevation of the floor slab 3 of the second layer, the original soil 1 on one side of the retaining structure 2 is excavated through the soil outlet 8 to form a horizontally extending second excavation surface 9 and a vertically extending third excavation surface 10, and after the inner wall of the retaining structure 2 on one side is exposed, the side wall 11 is poured on the inner wall of the retaining structure 2, specifically, a formwork is installed on one side of the retaining structure 2, a cavity is formed between the inner wall of the retaining structure 2 and the formwork, and the side wall 11 is formed by pouring concrete into the cavity. The upper side of the side wall 11 is poured together with the floor slab 3 of the first layer, and when the subsequent side wall 11 solidifies, the stability of the edge of the floor slab 3 can be improved. Without waiting for the side wall 11 to form strength, the original soil 1 is excavated to the other side of the retaining structure 2 to speed up the construction progress. The excavated original soil 1 is discharged to the ground through the soil outlet 8. In this step, the excavation surface does not involve the column cap 7, that is, the design position of the concrete column 6, so that the floor slab 3 and the column cap 7 are supported by the original soil 1, and the overall safety of the floor slab 3 is guaranteed.

[0062] S5: Pouring the floor slab and the concrete column of the second layer

[0063] As shown in Figure 2 , when the third excavation surface 10 approaches the column cap 7, specifically, the distance between the third excavation surface 10 and the axis of the concrete column 6 is d1, and the distance between the floor slab 3 of the first layer and the second excavation surface 9 is h, when d1 / h<=1 / 3, it is determined that the third excavation surface 10 approaches the column cap 7, and the excavation needs to be temporarily stopped, and a support column 12 is installed below the floor slab 3 of the first layer. The support head 127 at the upper end of the support column 12 supports the floor slab 3 of the first layer, and the base 122 at the lower end supports the second excavation surface 9, so that temporary support is prepared in advance to prevent collapse due to the decrease of the supporting property of the original soil 1 during subsequent excavation. After the original soil 1 is excavated to the other side of the column cap 7, the excavation is temporarily stopped, as shown in Figure 3 , at this time, the distance between the third excavation surface 10 and the axis of the concrete column 6 is d2, and d2 / h>=1 / 3, so the excavation needs to be temporarily stopped to prevent collapse caused by excessive excavation. At this time, the lower side of the column cap 7 is exposed, the floor slab 3 of the second layer is poured on the second excavation surface 9, and the concrete column 6 is poured below the column cap 7. The excavation is stopped before the concrete column 6 and the floor slab 3 form strength to prevent the construction quality of the floor slab 3 and the concrete column 6 from being affected by vibration and mechanical impact.

[0064] During the excavation of the original soil 1, the plywood formwork for pouring the floor slab 3 is laid as excavated to further speed up the construction speed. When the support column 12 is installed, the lower end of the support column 12 supports the formwork, which can disperse the stress of the expansion column 121 on the second excavation surface 9 at this time to reduce the subsidence of the second excavation surface 9, thereby improving the stability of the support column 12 and the floor slab 3 of the first layer.

[0065] When pouring the concrete column 6, first bind the steel bars at the position of the concrete column 6, connect the upper end of the steel bars of the concrete column 6 with the steel bars embedded in the column cap 7, then install the formwork around the steel bars, pour the concrete in the formwork to shape the concrete column 6, and after the strength of the concrete column 6 is formed, remove the formwork.

[0066] After the support column 12 is installed, the base 122 is supported on the second excavation surface 9, the telescopic mechanism 123 drives the telescopic column 121 to extend, the support head 127 at the upper end of the telescopic column 121 supports the first layer of the floor slab 3, the telescopic mechanism 123 has a self-locking function to prevent the telescopic column 121 from shortening, thereby stably supporting the first layer of the floor slab 3 by the support column 12; after the second layer of the floor slab 3 is poured, the upper end of the base 122 is flush with the upper end surface of the second layer of the floor slab 3, and after the floor slab 3 is solidified, the base 122 is fixedly embedded in the second layer of the floor slab 3.

[0067] S6: Excavate the whole layer of original soil

[0068] As shown in Figure 4 , after the concrete column 6 and the second layer of the floor slab 3 are formed to have strength, the support column 12 is removed, the base 122 of the support column 12 is embedded in the second layer of the floor slab 3, and the soil on the other side of the enclosure structure 2 is continuously excavated, when the third excavation surface 10 approaches the next column cap 7, S5 is repeated until the whole layer of original soil 1 is excavated, after the construction of the second layer of the floor slab 3 is completed, the space of the first underground layer is formed, the soil outlet 8 is reserved near the edge of the second layer of the floor slab 3, the soil outlet 8 of the first layer of the floor slab 3 and the soil outlet 8 of the second layer of the floor slab 3 are correspondingly positioned, which facilitates the excavation of the next layer of original soil 1, and the column cap 7 is poured at the lower side of the second layer of the floor slab 3, which facilitates the connection with the upper end of the concrete column 6 in the space of the second underground layer.

[0069] When the support column 12 is removed, the telescopic mechanism 123 drives the telescopic column 121 to contract, the support head 127 at the upper end of the telescopic column 121 is separated from the first layer of the floor slab 3, and after the base 122 is separated from the lower end of the telescopic column 121, the support column 12 can be removed, and after a new base 122 is replaced, the floor slab 3 can be supported again.

[0070] S7: Pour the remaining side wall

[0071] The remaining side wall 11 is continuously poured on the inner wall of the enclosure structure 2, so that the inner wall of the current layer of the enclosure structure 2 is poured with the side wall 11, thereby further improving the stability of the edge of the floor slab 3.

[0072] S8: As shown in Figures 5-7 , the construction of S2-S7 is repeated to form the space of the second underground layer, the third layer of the floor slab 3 formed this time is the bottom plate of the underground space structure, and it is not necessary to reserve the soil outlet 8 and pour the column cap 7.

[0073] In other embodiments, if the third layer of slab 3 under construction is not the last layer of slab 3, an excavation opening 8 needs to be reserved on the third layer of slab 3, and a column cap 7 of the next layer needs to be poured at the lower end of the concrete column 6, and construction S2-S7 is repeated until the last layer is completed.

[0074] Example 2:

[0075] like Figure 8 As shown, this embodiment provides an underground space cover-excavation reverse construction device, the construction device is a support column 12, which is used to temporarily support the layer plate 3. The support column 12 includes a telescopic column 121, a base 122, a telescopic mechanism 123, a support head 127 and a mobile support mechanism.

[0076] Specifically, the telescopic column 121 includes a sleeve 1211 and a support rod 1212. The sleeve 1211 is detachably arranged at the upper end of the base 122. The support rod 1212 is slidably arranged in the sleeve 1211 to facilitate supporting shelves 3 of different heights. The support head 127 is integrally arranged at the upper end of the support rod 1212.

[0077] The sleeve 1211 is a hollow square tube structure, the cross section of the support rod 1212 is square, the cross section area of ​​the support rod 1212 is smaller than the cross section area of ​​the sleeve 1211 , and the support rod 1212 is adapted to the sleeve 1211 .

[0078] like Figure 11 As shown, the lower end of the sleeve 1211 is integrally provided with a protruding fixing key, and the upper end of the base 122 is provided with a slot adapted to the fixing key. The fixing key of the sleeve 1211 is inserted into the slot of the base 122, and the sleeve 1211 can be directly pulled out from the base 122 upward.

[0079] In this embodiment, the movable support mechanism is disposed on the side wall of the support rod 1212 , and when the support rod 1212 is not completely retracted into the sleeve 1211 , the movable support mechanism can be in close contact with the ground.

[0080] Among them, the mobile support mechanism includes two mobile support components, which are symmetrically arranged on the side walls of the support rod 1212. The mobile support components include a side frame 125 and two wheels 124. The top of the side frame 125 is rotatably connected to the side wall of the support rod 1212, and the bottom of the side frame 125 is rotatably connected to the wheels 124 respectively.

[0081] In this embodiment, the side frame 125 is in an inverted V shape.

[0082] When the telescopic mechanism 123 drives the telescopic column 121 to shorten, the support rod 1212 is retracted downward and separated from the upper layer plate 3, the moving support assembly moves downward with the support rod 1212, and the wheel 124 contacts the lower cured layer plate 3. Then, the telescopic column 121 continues to shorten, so that the sleeve 1211 moves upward and separates from the base 122. The support column 12 is moved to the next support point by the wheel 124 to support the layer plate 3.

[0083] When re-supporting, the new base 122 is placed on the second excavation surface 9, the fixing key at the lower end of the sleeve 1211 is aligned with the slot of the base 122, the telescopic mechanism 123 drives the telescopic column 121 to lengthen, so that the sleeve 1211 moves downward, and the lower end of the sleeve 1211 is inserted into the base 122. Then, the telescopic column 121 continues to lengthen, so that the support rod 1212 moves upward and drives the moving support assembly to move upward, and finally the support head 127 at the upper end of the support rod 1212 abuts against the upper layer plate 3.

[0084] In this embodiment, the telescopic mechanism 123 is arranged at the connection between the sleeve 1211 and the support rod 1212 to adjust the length of the telescopic column 121.

[0085] Specifically, as shown in Figures 9-10 The telescopic mechanism 123 includes a battery 1231, a motor 1232, a worm wheel 1233, a worm gear 1234, a driving gear and a rack 1235. The rack 1235 is welded to the lower side wall of the support rod 1212, the driving gear is welded to the upper end of the sleeve 1211 and engages with the rack 1235, the worm wheel 1233 is coaxially arranged on one side of the driving gear, the worm gear 1234 is arranged in cooperation with the worm wheel 1233, the motor 1232 is welded to the side wall of the sleeve 1211 and connected with the worm gear 1234, and the battery 1231 is welded between the side frames 125 and located on the side opposite to the rack 1235. The battery 1231 is electrically connected with the motor 1232, the motor 1232 is powered by the battery 1231, the motor 1232 drives the support rod 1212 and the sleeve 1211 to move up and down through the worm gear 1234, the worm wheel 1233, the driving gear and the rack 1235, so as to drive the telescopic column 121 to extend or retract. The cooperation between the worm gear 1234 and the worm wheel 1233 has self-locking characteristics, and when the motor 1232 stops working, the length of the telescopic column 121 is fixed.

[0086] Two side frames 125 are located at one side of the battery 1231 and close to the upper end between the welding limit rod 126, the limit rod 126 is a rectangular parallelepiped, and the limit rod 126 is in contact with the side wall of the support rod 1212 under the action of gravity. When the support column 12 supports the layer plate 3, after pouring the layer plate 3, the wheel 124 is suspended on the upper side of the layer plate 3, under the action of gravity, the limit rod 126 is in contact with one side of the support rod 1212, so as to prevent the side frame 125 and the wheel 124 from shaking, and avoid the collision between the wheel 124 and the layer plate 3 which is not yet solidified.

[0087] The above application of specific examples to the present application is described, only for helping to understand the present application, and does not limit the present application. For the skilled in the art to which the present application belongs, according to the idea of the present application, a number of simple deductions, deformation or replacement can be made.

Claims

1. The underground space cover-excavation reverse construction method is characterized by: The construction method comprises the following steps: Construction enclosure (2); Casting the first layer of slabs and column caps: excavating earth on the inner side of the enclosure structure (2) according to the design elevation of the first layer of slabs (3) and the design position of the concrete columns (6) to form a horizontally extending first excavation surface (4), casting the first layer of slabs (3) and column caps (7) above the first excavation surface (4), casting the edges of the first layer of slabs (3) together with the enclosure structure (2), and reserving an earth-excavation opening (8) near the edge of the first layer of slabs (3); Backfilling earthwork: after the first layer of the layer plate (3) has formed strength, backfilling earthwork is carried out on the first layer of the layer plate (3) to open the road to traffic; Excavating the original soil on one side and casting the side wall: according to the design elevation of the second layer plate (3), excavating the original soil (1) on one side of the enclosure structure (2) through the excavation opening (8) to form a second excavation surface (9) extending horizontally and a third excavation surface (10) extending vertically; after the inner wall of one side of the enclosure structure (2) is exposed, casting the side wall (11) on the inner wall of the enclosure structure (2); the upper side of the side wall (11) is cast together with the first layer plate (3); and continuing to excavate the original soil (1) toward the other side of the enclosure structure (2); Casting the second layer of slabs and concrete columns: when the third excavation surface (10) is close to the column cap (7), excavation is suspended, and a support column (12) is installed below the first layer of slabs (3), the upper end of the support column (12) supports the first layer of slabs (3), and the lower end is supported on the second excavation surface (9), and excavation is suspended after the original soil (1) is continuously excavated to the other side of the column cap (7), and the second layer of slabs (3) is cast on the second excavation surface (9), and the concrete column (6) is cast below the column cap (7); Excavating the entire layer of original soil: after the concrete column (6) and the second layer of the slab (3) have formed strength, the support column (12) is removed, the lower end of the support column (12) is buried in the second layer of the slab (3), and the soil is continued to be excavated toward the other side of the enclosure structure (2). When the third excavation surface (10) is close to the next column cap (7), the steps of pouring the second layer of the slab and the concrete column are repeated until the entire layer of original soil (1) is excavated; Casting the remaining side walls: continuing to cast the remaining side walls (11) on the inner wall of the enclosure structure (2).

2. The underground space cover-excavation reverse construction method according to claim 1 is characterized in that: When the layer plate (3) constructed in the step of pouring the second layer of layer plates and concrete columns and excavating the entire layer of original soil is not the layer plate (3) of the last layer, it is necessary to reserve the excavation opening (8) on the layer plate (3) of the second layer, and pour the column cap (7) of the next layer at the lower end of the concrete column (6), and repeat the steps of excavating the original soil (1) on one side and pouring the side wall, pouring the second layer of layer plates and concrete columns, excavating the entire layer of original soil and pouring the remaining side walls until the construction of the last layer is completed.

3. The underground space cover-excavation reverse construction method according to claim 2 is characterized in that: Steel bars are pre-embedded in the column cap (7), and the lower ends of the steel bars extend outside the column cap (7).

4. The underground space cover-excavation reverse construction method according to claim 3 is characterized in that: When pouring the concrete column (6), first, steel bars are tied at the position of the concrete column (6), and the upper ends of the steel bars of the concrete column (6) are connected to the steel bars pre-buried in the column cap (7). Then, a template is installed around the steel bars, and concrete is poured in the template to form the concrete column (6). After the strength of the concrete column (6) is formed, the template is removed.

5. Underground space cover-excavation reverse construction device, characterized by: The construction device comprises the support column (12) for temporarily supporting the layer plate (3), and the support column (12) comprises a telescopic column (121), a base (122), a telescopic mechanism (123), a support head (127) and a movable support mechanism; The telescopic column (121) comprises a sleeve (1211) and a support rod (1212); the sleeve (1211) is detachably arranged on the upper end of the base (122); the support rod (1212) is slidably arranged in the sleeve (1211); and the support head (127) is arranged on the upper end of the support rod (1212); The telescopic mechanism (123) is provided at the connection between the sleeve (1211) and the support rod (1212); The movable support mechanism is arranged on the side wall of the support rod (1212), and when the support rod (1212) is not completely retracted into the sleeve (1211), the movable support mechanism can be in close contact with the ground.

6. The underground space cover-excavation reverse construction device according to claim 5 is characterized in that: The lower end of the sleeve (1211) is provided with a protruding fixing key.

7. The underground space cover-excavation reverse construction device according to claim 6 is characterized in that: The upper end of the base (122) is provided with a slot adapted to the fixed key.

8. The underground space cover-excavation reverse construction device according to claim 5 is characterized in that: The mobile support mechanism includes a plurality of mobile support assemblies, the mobile support assemblies are symmetrically arranged on the side walls of the support rod (1212), the mobile support assemblies include side frames (125) and a plurality of wheels (124), the tops of the side frames (125) are rotatably connected to the side walls of the support rod (1212), and the bottoms of the side frames (125) are respectively rotatably connected to the wheels (124).

9. The underground space cover-excavation reverse construction device according to claim 8, characterized in that: The telescopic mechanism (123) comprises a battery (1231), a motor (1232), a worm wheel (1233), a worm (1234), a driving gear and a rack (1235); the rack (1235) is arranged below the side wall of the support rod (1212); the driving gear is arranged at the upper end of the sleeve (1211) and meshes with the rack (1235); the worm wheel (1233) is coaxially arranged on one side of the driving gear; the worm (1234) and the worm wheel (1233) are arranged in coordination; the motor (1232) is arranged on the side wall of the sleeve (1211) and connected to the worm (1234); the battery (1231) is arranged between the side frames (125) and on the side opposite to the rack (1235); and the battery (1231) is electrically connected to the motor (1232).

10. The underground space cover-excavation reverse construction device according to claim 8, characterized in that: A limiting rod (126) is provided between the side frames (125).

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