Cantilever type side wall self-stabilizing system applied to deep foundation pit support

Abstract

The utility model discloses a cantilever type side wall self-stabilizing system applied to deep foundation pit supporting, which comprises two waterproof curtains, a supporting pile, a concrete protection slope and an underpass channel box culvert, a plurality of soil nails are arranged in the concrete protection slope, a top beam is arranged at the top of the supporting pile, and a wet lean concrete layer is arranged on the inner side of the supporting pile. A plurality of columns of additional supporting steel bars arranged at intervals are arranged in structural steel bars of the underpass channel box culvert, the underpass channel box culvert comprises an underpass channel bottom plate, an underpass channel top plate and two underpass channel side walls, one ends of the additional supporting steel bars are inserted into the underpass channel side walls, and the other ends of the additional supporting steel bars penetrate through vertical side wall sections of the underpass channel bottom plate. The side wall panel is arranged on the transverse bottom wall section of the underpass channel bottom plate and is bent and inserted into the transverse bottom wall section of the underpass channel bottom plate so as to ensure the bending bearing capacity of the underpass channel bottom plate, so that a switching support structure in the prior art can be replaced, the pressure intensity of the side wall panel is small, the rigidity and the shock resistance of the whole structure are improved, and the construction period can be obviously shortened.

Description

TECHNICAL FIELD

[0001] The utility model relates to a foundation pit support technical field, especially a cantilever type side wall self-stabilizing system for deep foundation pit support, and is especially suitable for the foundation pit support operation of the foundation pit surrounding geological complexity, many underground pipelines and the depth of the inner support not greater than 8 meters. BACKGROUND

[0002] The foundation pit engineering is the underground space excavated from the ground, and the vertical enclosure structure is arranged around, and generally a certain depth of the insert plate (or pile) wall structure is arranged under the excavation face base.

[0003] At present, the foundation pit support usually adopts the inverted strut structure to reduce the deformation of the enclosure structure and control the wall body bending moment, but the inverted strut directly supports the inner surface of the side wall panel, causes the stress area of the side wall panel to be very small, and further easily leads to the deformation and damage of the side wall panel.

[0004] In addition, the box culvert structure of each section is generally provided with 9 inverted struts, and the inverted struts of each section need to be repeatedly installed and removed, which is quite time-consuming and labor-consuming. SUMMARY

[0005] Therefore, the utility model provides a cantilever type side wall self-stabilizing system for deep foundation pit support, which can replace the inverted strut structure of the prior art, the pressure of the side wall panel is smaller, the rigidity and the anti-seismic ability of the overall structure are improved, and the construction period can be obviously shortened.

[0006] In order to achieve the above object, the utility model provides the technical scheme as follows:

[0007] The utility model provides a cantilever type side wall self-stabilizing system for deep foundation pit support, which includes two water stop curtains, a support pile arranged between the water stop curtains, a concrete slope arranged between the water stop curtains and the support pile, a plurality of soil nails arranged in the concrete slope, a corbel arranged at the top of the support pile, a wet lean concrete layer arranged at the inner side of the support pile, and a lower passage box culvert arranged between the two wet lean concrete layers.

[0008] Further, at least 4 additional support steels are additionally arranged in the sidewall of the lower passage box culvert per meter.

[0009] Further, the diameter of the additional supporting steel bars is 28mm, and the interval is 25mm.

[0010] Further, the additional supporting steel bars comprise vertical segments and elbow segments, one end of the vertical segments is inserted into the side wall of the underpass, and the other end of the vertical segments is inserted into the vertical side wall segment of the underpass bottom plate; the elbow segments are inserted into the horizontal bottom wall segment of the underpass bottom plate.

[0011] Further, the lengths of the vertical segments and the elbow segments are equal.

[0012] The technical scheme has the following beneficial effects:

[0013] The underpass box culvert of the utility model is a beam-column-free structure, and compared with the inverted bracing structure of the prior art, the side wall panel of the utility model is subjected to smaller pressure under the action of the same earth pressure, and the integrity and safety of the side wall structure are higher, so that the utility model can not only effectively replace the inverted bracing structure, but also improve the rigidity and seismic capacity of the overall structure, and can also strengthen the concrete crack resistance and improve the safety of the redundant structure, thereby ensuring that the underpass is in a safe use state for a long time.

[0014] The utility model does not need to install and remove the inverted bracing structure of the prior art, and therefore, the utility model can also obviously shorten the construction period, effectively save the construction cost and improve the construction efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 Fig. 1 shows a schematic diagram of the underpass box culvert in the embodiment;

[0016] Figure 2 Fig. 2 shows a reinforcement diagram of the underpass box culvert in the embodiment;

[0017] Figure 3 Fig. 3 shows a sectional view of A-A in the embodiment; Figure 2

[0018] Figure 4 Fig. 4 shows a state schematic diagram of step S1 of the construction method in the embodiment;

[0019] Figure 5 Fig. 5 shows a state schematic diagram of step S2 of the construction method in the embodiment;

[0020] Figure 6 Fig. 6 shows a state schematic diagram of step S3 of the construction method in the embodiment;

[0021] Figure 7 Fig. 7 shows a state schematic diagram of step S4 of the construction method in the embodiment; ​

[0022] Figure 8 Fig. 5 shows a schematic diagram of a state of step S5 of the construction method in the embodiment;

[0023] Figure 9 Fig. 6 shows a schematic diagram of a state of step S6 of the construction method in the embodiment. DETAILED DESCRIPTION

[0024] To further illustrate the embodiments, the utility model provides the accompanying drawings. These accompanying drawings are part of the utility model disclosure, which mainly serves to illustrate the embodiments, and can be used to explain the operating principle of the embodiments in conjunction with the related description of the specification. With reference to these contents, those skilled in the art should be able to understand other possible embodiments and the advantages of the utility model. The components in the drawings are not drawn to scale, and similar component symbols are usually used to represent similar components.

[0025] The utility model will be further illustrated in conjunction with the accompanying drawings and specific embodiments.

[0026] Reference Figures 1 to 9 As shown, the embodiment provides a cantilever side wall self-stabilizing system for deep foundation pit support (hereinafter referred to as cantilever side wall self-stabilizing system), including as Figure 9 As shown, two water stop curtains 2, support piles 1 arranged between the water stop curtains 2, concrete retaining walls 3 arranged between the water stop curtains 2 and the support piles 1, three soil nails 31 are respectively arranged in the concrete retaining walls 3, the top of the support piles 1 is provided with a corbel 5, and the inner side of the support piles 1 is provided with a wet lean concrete layer 7.

[0027] The cantilever side wall self-stabilizing system of the embodiment further includes a lower passage box culvert 8 arranged between the two wet lean concrete layers 7 as shown. Figure 1 The structure steel bars of the lower passage box culvert 8 are provided with multiple rows of additional support steel bars 9 arranged at intervals, and include a lower passage bottom plate 81, a lower passage top plate 83 and two lower passage side walls 82 between the lower passage bottom plate 81 and the lower passage top plate 83.

[0028] One end of the additional support steel bar 9 is inserted into the lower passage side wall 82, the other end passes through the vertical side wall section 811 of the lower passage bottom plate 81, and is bent and inserted into the horizontal bottom wall section 812 of the lower passage bottom plate 81, so as to ensure the bending bearing capacity of the lower passage bottom plate 81.

[0029] In the embodiment, 4 additional support steel bars 9 are added per meter in the side wall of the lower passage box culvert 8, and the diameter of the additional support steel bar 9 is 28mm, and the interval thereof is 25mm.

[0030] In more detail, Figure 1 , Figure 2 and Figure 3As shown, the additional support steel bars 9 include a vertical segment 91 and an elbow segment 92, the upper end of the vertical segment 91 is inserted into the lower passage side wall 82, the lower end of the vertical segment 91 is inserted into the vertical side wall segment 811 of the lower passage floor 81, and the elbow segment 92 is inserted into the horizontal bottom wall segment 812 of the lower passage floor 81, at this time, the vertical segment 91 and the elbow segment 92 are crossed at 90 degrees, and the lengths of the vertical segment 91 and the elbow segment 92 are equal.

[0031] In particular implementation, the construction method described below is used to construct the cantilever side wall self-stabilizing system of the embodiment, and includes the following specific steps:

[0032] As shown in Figure 4 Step S1, the construction site is leveled to a site level of 12.0 m, then the water stop curtain 2 is constructed, and then the site is excavated with a slope between the two water stop curtains 2, that is, the site is excavated with a slope on the ground of the site level of 12.0 m to 6.1 m (such as miscellaneous fill, silty clay, etc.), and the earthwork is excavated to a level of 7.0 m, then the slope top guardrail 12 is set, then at least three soil nails 31 are constructed to form a slope support, and then the shotcrete slope protection 3 and the support pile 1 are successively driven.

[0033] As shown in Figure 5 Step S2, the underground water in the construction site is pumped out to dryness when the bottom of the foundation pit is at a level of 0.5 m, then the soil on top of the support pile 1 is excavated, and the corbel 5 is constructed on top of the support pile 1, then the reinforced concrete support 61 is constructed between the two corbels 5, and the top of the reinforced concrete support 61 is at a level of 7.0 m; after the concrete strength of the corbel 5 and the reinforced concrete support 61 meets the design requirements, the lower part of the earthwork is continuously excavated, and the steel enclosing purlin 63 and the steel support 62 are erected, the top of the steel support 62 is at a level of 3.5 m, to form a deep foundation pit, and the overbreak depth of each support during erection does not exceed 0.5 m.

[0034] As shown in Figure 6 Step S3, the structural steel bars of the lower passage side wall and the lower passage floor are respectively arranged on both sides and the bottom of the deep foundation pit according to the pre-design, and are arranged at intervals with the support pile 1, then the additional support steel bars 9 are arranged in a binding manner, then the lower passage floor 81 is poured, the lower passage floor 81 includes the vertical side wall segment 811 and the horizontal bottom wall segment 812, and is provided with a cushion layer and a waterproof layer, at this time, the vertical side wall segment 811 is part of the side wall structure, and the top of the vertical side wall segment 811 is at a level of 2.45 m; after the concrete strength of the lower passage floor 81 meets the design requirements, the wet lean concrete is backfilled in the fat groove between the support pile 1 and the lower passage floor 81.

[0035] As shown in Figure 7As shown, in step S4, after the strength of the wet lean concrete in step S3 meets the design requirements, the steel support 62 and the steel waler 63 are removed in sequence, and then the underpass side wall 82 is poured. At this time, the top elevation of the two underpass side walls 82 is 5.5m. After the concrete strength of the underpass side wall 82 meets the design requirements, the wet lean concrete is backfilled into the trench between the support pile 1 and the underpass side wall 82.

[0036] like Figure 8 As shown, in step S5, after the strength of the wet lean concrete in step S4 meets the design requirements, the reinforced concrete support 61 is removed, and then a disc-lock full-span scaffold 11 is erected. Then, the underpass top slab 83 is constructed above the disc-lock full-span scaffold 11. After the concrete strength of the underpass bottom slab 81 meets the design requirements, the wet lean concrete is backfilled into the trench between the support pile 1 and the underpass top slab 83.

[0037] like Figure 9 As shown, in step S6, after the strength of the wet lean concrete in step S5 meets the design requirements, the entire disc-lock full-span scaffold 11 is pulled to the working surface of the next segment using the traction and moving device of utility model patent CN215564490U, and steps S2 to S5 are repeated until the entire underpass box culvert 8 at the construction site is completed.

[0038] Step S7: Backfill and compact the soil in layers above the top slab 83 of the underpass, starting from an elevation of 8.9m above the top slab 83 and continuing until the site level reaches 12.0m. A waterproof layer and a protective layer are also installed above the top slab 83 of the underpass.

[0039] After all construction is completed, the side walls of the underpass box culvert 8 bear earth pressure loads, and its bottom bears uniformly distributed loads (mainly from the self-weight of the structure and the loads from the finishing surface). At this time, the bending moment at the connection between the side walls and the bottom of the underpass box culvert 8 is relatively large. Therefore, the bent section 92 of the additional supporting steel bar 9 is extended to the transverse bottom wall section 812 of the underpass bottom slab 81 to serve as additional steel bars at the bottom of the underpass box culvert 8, thereby increasing the reinforcement ratio and thus increasing its bottom bending bearing capacity.

[0040] Furthermore, in this embodiment, the underpass bottom slab 81 is 1.2m thick, the underpass sidewall 82 is 3.8m high, the retaining wall is 5.0m high, and the back soil density of the retaining wall is taken as 20KN / m³. 3, the static earth pressure coefficient is 1-sin30°, then the reinforcement calculation and multiple field data testing are carried out to determine that 4 additional supporting steels 9 are additionally arranged in the side wall of the underpass box culvert 8 per meter, the vertical segment 91 length of the additional supporting steel 9 is 4.9m, the elbow length of the additional supporting steel 9 is 4.9m, and the material of the additional supporting steel 9 is HRB400 steel, so that the maximum crack width of the cantilever type side wall self-stabilizing system of the embodiment is less than 0.2mm, so as to meet the crack control requirement.

[0041] In summary, the underpass box culvert 8 of the embodiment is a beam-column-free structure, and compared with the inverted strut structure of the prior art, the side wall panel of the embodiment is subjected to smaller pressure under the action of the same earth pressure, and the integrity and safety of the side wall structure are higher, so that the embodiment not only can effectively replace the inverted strut structure, but also can improve the rigidity and seismic capacity of the overall structure, and can strengthen the concrete crack resistance and improve the safety of the redundant structure, so as to ensure that the underpass is in a safe use state for a long time.

[0042] In addition, Table 1 as shown below is the construction days of the inverted strut of the prior art, and Table 2 as shown below is the construction days of the cantilever type side wall self-stabilizing system of the embodiment.

[0043] Table 1: Construction days of inverted strut of prior art

[0044]

[0045] Table 2: Construction days of cantilever type side wall self-stabilizing system of the embodiment

[0046]

[0047] According to Tables 1 and 2, the embodiment does not need to install and remove the inverted strut structure of the prior art, so the embodiment can also significantly shorten the construction period, effectively save the construction cost and improve the construction efficiency.

[0048] Although the utility model is specifically shown and introduced in combination with the preferred embodiment, it should be understood by those skilled in the art that various changes can be made to the utility model in form and detail without departing from the spirit and scope of the utility model defined in the appended claims, and all changes are within the protection scope of the utility model.

Claims

1. A cantilevered sidewall self-stabilizing system for deep foundation pit support, comprising two water-stopping curtains, a support pile arranged between the water-stopping curtains, a concrete slope protection arranged between the water-stopping curtains and the support pile, a plurality of soil nails arranged in the concrete slope protection, a corbel arranged at the top of the support pile, and a wet lean concrete layer arranged at the inner side of the support pile, characterized in that: The lower passage box culvert is provided with a plurality of rows of additional support steels arranged at intervals in the structural steel bars, and comprises a lower passage bottom plate, a lower passage top plate and two lower passage side walls between the lower passage bottom plate and the lower passage top plate; one end of the additional support steel is inserted into the lower passage side wall, the other end of the additional support steel is inserted through the vertical side wall section of the lower passage bottom plate, and is bent and inserted into the horizontal bottom wall section of the lower passage bottom plate, so as to ensure the bending bearing capacity of the lower passage bottom plate. ​ The lower passage box culvert is provided with at least 4 additional support steels per meter of the side wall.

2. The self-stable cantilevered sidewall system for deep foundation pit support according to claim 1, wherein: The diameter of the additional support steel is 28mm, and the interval thereof is 25mm.

3. The self-stable cantilevered sidewall system for deep foundation pit support according to claim 2, wherein: The additional support steel comprises a vertical section and an elbow section; one end of the vertical section is inserted into the lower passage side wall, and the other end of the vertical section is inserted through the vertical side wall section of the lower passage bottom plate; the elbow section is inserted into the horizontal bottom wall section of the lower passage bottom plate.

4. The self-stable cantilevered sidewall system for deep foundation pit support according to any one of claims 1-3, characterized in that: The lengths of the vertical section and the elbow section are equal.

5. The self-stable cantilevered sidewall system for deep foundation pit support according to claim 4, characterized in that: ​

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