Layered supporting structure in pit-in-pit construction process

Abstract

The utility model discloses a layered support structure in a pit-in-pit construction process in the technical field of pit-in-pit, which comprises a pit-in-pit, a side support baffle, a reinforcing enclosing purlin and a support rod, the side wall of the pit-in-pit is enclosed by the side support baffle, the side support baffle is reinforced and supported by the reinforcing enclosing purlin, and the support rod is arranged on the side wall of the pit-in-pit. The reinforcing enclosing purlins are oppositely supported and abut against each other through the supporting rods, it is ensured that the side supporting baffles are stably supported in the pit, the soil layer wall of the pit in the pit which is being excavated can be effectively supported through the side supporting baffles, the side supporting baffles can be continuously spliced, and therefore the pit in the pit is effectively supported; the flexible supporting mode of the device for the stratum can deal with the situation that the soil layer of the pit-in-pit is prone to deformation, reinforcement can be conducted on the failure of an original supporting structure of the pit-in-pit, waiting for concrete condensation is not needed, the supporting construction speed is high, the effect taking speed is high, and the excavation process of the pit-in-pit is safer.

Description

Technical Field

[0001] The utility model relates to the technical field of a pit in a pit, in particular to a layered support structure in a pit in a pit construction process. Background Art

[0002] Foundation pit engineering refers to the space below the ground excavated for the construction of building foundations and basements.

[0003] There are a large number of foundation pit projects in the field of engineering construction. With the large-scale development of underground space, foundation pit projects are developing in the direction of deep and large, and are also facing more complex geological conditions. In many cases, pits need to be excavated in the foundation pit. A pit in a pit is a small foundation pit in a large foundation pit, which is commonly found in elevator shafts, water collection wells, high caps and other parts. The characteristic of a pit in a pit is that the excavation depth is deeper than that of a large foundation pit. The depth of different pits in different pits is different, and the common depth is 2 to 4 meters. The pit in the pit is the prerequisite for the construction of elevator shaft structures, water collection well structures and caps. The support method of the pit in the pit needs to be designed according to the geological conditions, the plane shape of the pit in the pit, the depth and the position in the large foundation pit. Common pit in the pit methods are: 1. Before the excavation of the large foundation pit, a cement soil mixing pile gravity retaining wall or cast-in-place pile is constructed on the original ground in advance; 2. After the excavation of the large foundation pit, a steel sheet pile is inserted at the bottom of the large foundation pit; 3. After the excavation of the large foundation pit, the pit in the pit is excavated while spraying anchors or cast-in-place concrete facing structures.

[0004] There are some technical defects in the existing pits in the foundation pits: (1) The cement mixing pile gravity retaining wall in the pit is generally suitable for pits with smaller excavation depths. When the depth of the pit exceeds 2 meters, it is generally considered to be too deep. At this time, it is necessary to increase the depth and thickness of the mixing pile gravity retaining wall to ensure the safety of the side walls of the foundation pit. The construction methods of mixing piles and cast-in-place piles are relatively complicated, costly, and the quality controllability is relatively poor; (2) The installation of steel sheet piles in the pit needs to be carried out after the excavation reaches the bottom of the large foundation pit. The site needs to be able to accommodate the construction space of large pile driving equipment. The construction space in the foundation pit is limited. Moreover, due to the limitation of site conditions, it is extremely difficult to recover the steel sheet piles inserted in the pit within the pit; (3) The pit within the pit sprayed anchor support has the characteristics of a large slope range and a large amount of earth excavation. The large excavation depth may also cause the foundation piles around the pit within the pit to tilt. This support method is not conducive to implementation in the pit within the pit; (4) The cast-in-place concrete protective panel in the pit within the pit needs to wait for the concrete to solidify, and the construction time is long. Especially after the soil layer is excavated in the soft soil area, the soil layer deforms quickly. Before the concrete support structure can play its supporting role, the pit within the pit may have failed. This method has poor stratum applicability and can only be used in strata with better soil and rock quality.

[0005] Based on this, the utility model designs a layered support structure during the pit-in-pit construction process to solve the above problems. Utility Model Content

[0006] The purpose of the utility model is to provide a layered support structure in the process of pit-in-pit construction, which can effectively support the wall of the soil layer of the pit-in-pit being excavated through side support baffles, and as the excavation construction progresses, the side support baffles can be continuously spliced ​​to effectively support the pit-in-pit, and as long as the side support baffles are abutted, the stratum can be effectively supported. Moreover, the flexible support method for the stratum of the device can cope with the situation that the soil layer of the pit-in-pit is easy to deform, and can also reinforce the failure of the original pit-in-pit support structure, and there is no need to wait for the concrete to solidify. The support construction speed is fast and the effect is fast, making the pit-in-pit excavation process safer.

[0007] The utility model is implemented as follows: a layered support structure in a pit-in-pit construction process, comprising:

[0008] Pit-in-pit, side support baffles, reinforced purlins and support rods;

[0009] The pit in the pit is a pit excavated downwards at the bottom of the building foundation pit, the top of the pit in the pit is flush with the bottom of the foundation pit, and the bottom of the pit in the pit is a leveled pit bottom;

[0010] The side support baffle is a flat steel plate, and the side support baffle is against the side wall of the pit in the pit, and the four vertical side walls of the pit in the pit are vertically arranged and covered with side support baffles;

[0011] The reinforced purlin is a steel straight rod-shaped purlin, and the reinforced purlin is horizontally erected on the inner side of the side support baffle, and the outer side of the side support baffle is in contact with the vertical side wall of the pit in the pit;

[0012] The support rod is a steel straight rod, and the support rod is clamped between the reinforced purlins on two opposite vertical side walls at the same height in the pit. The support rod can be detachably pressed between the two opposite reinforced purlins.

[0013] The beneficial effects of the utility model are as follows: 1. The utility model uses the existing steel structure side support baffle as the supporting structure of the soil layer, and does not need to wait for the concrete to solidify and form, and can take effect immediately after the support is completed, which can make the construction safer, without a safety window period, and effectively shorten the construction period;

[0014] 2. The construction method is simple, and does not require the use of large equipment or concrete pile foundations. It only requires the installation of side support baffles, which can effectively support the pit in the pit, and does not require the use of concrete mixing and cast-in-place pile foundations;

[0015] 3. This device can effectively control the ground deformation of the pit in the pit during the excavation process and play a more stable supporting role. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below in conjunction with the embodiments with reference to the accompanying drawings.

[0017] Figure 1 This is a schematic diagram of the overall side structure of the utility model;

[0018] Figure 2 It is a structural schematic diagram of the front splicing state of the side support baffle of the utility model.

[0019] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0020] 1-pit within pit, 11-sealing layer, 12-foundation pit, 2-side support baffle, 21-connecting steel plate, 3-reinforced purlin, 31-steel corbel, 4-support rod. DETAILED DESCRIPTION

[0021] See also Figures 1 to 2 As shown, the utility model provides a layered support structure during the pit-in-pit construction process. In order to better understand the above technical solution, the above technical solution will be described in detail below in combination with the drawings in the specification and specific implementation methods.

[0022] In a specific embodiment of the technical solution of the utility model:

[0023] It includes a pit in a pit 1, a side support baffle 2, a reinforced purlin 3 and a support rod 4;

[0024] The pit in the pit 1 is a pit excavated downward from the bottom of the building foundation pit 12. The top of the pit in the pit 1 is flush with the bottom of the foundation pit 12. The bottom of the pit in the pit 1 is a leveled sealing layer 11 formed by pouring quick-setting concrete. The sealing layer 11 is relatively important and plays a role in quickly controlling the uplift and deformation of the bottom of the pit in the pit 1. After the final excavation of the pit in the pit 1 is completed, the bottom of the pit needs to be sealed. The sealing layer 11 of the bottom of the pit is constructed by pouring quick-setting concrete or stacking sandbags. The sealing layer 11 can quickly form a pile pressure counterweight at the bottom of the pit to protect the soil layer at the bottom of the pit in the pit 1. The thickness of the sealing layer is determined according to the stability of the bottom of the pit. The bottom of the pit in the pit 1 is the maximum excavation depth of the pit in the pit 1. The depth after the sealing layer 11 is constructed should not be less than the buried depth of the main structure of the pit in the pit 1. That is, even after the bottom of the pit is sealed, it is necessary to ensure that the height of the bottom of the pit meets the design depth of the pit in the pit 1, that is, the depth of the sealing layer 11 meets the design requirements.

[0025] The side support baffles 2 are flat steel plates, which are against the side walls of the pit in the pit 1. The four vertical side walls of the pit in the pit 1 are vertically arranged and covered with side support baffles 2; multiple side support baffles 2 are vertically spliced ​​downward and aligned to fit on the vertical side walls of the pit in the pit 1. Connecting steel plates 21 are welded on the inner sides of the side support baffles 2. The upper and lower adjacent side support baffles 2 are welded into a vertical integral flat plate structure through the connecting steel plates 21. The side support baffles 2 are steel plates with a thickness of not less than 15 mm. The connecting steel plates 21 are used to connect the upper and lower side support baffles 2. The connecting steel plates 21 are arranged at intervals and are firmly connected.

[0026] The reinforced purlin 3 is a steel straight rod-shaped purlin, which is horizontally mounted on the inner side of the side support baffle 2, and the outer side of the side support baffle 2 is in contact with the vertical side wall of the pit 1; the two ends of the reinforced purlin 3 extend flush with the left and right sides of the side support baffle 2, and a plurality of steel corbels 31 are also arranged on the inner side of the side support baffle 2. The supporting surfaces of the steel corbels 31 on the same side support baffle 2 are in the same straight line, and the reinforced purlin 3 is stably mounted on the inner side of the side support baffle 2 through the steel corbels 31. The reinforced purlin 3 is made of channel steel or section steel, and its function is to improve the overall rigidity of the side support baffle 2 and the support of the side wall; the steel corbels 31 are made of steel plates, welded to the inner side wall of the side support baffle 2, and used to support the steel reinforced purlin 3.

[0027] The support rod 4 is a steel straight rod, and the support rod 4 is clamped between the reinforced purlins 3 on the two opposite vertical side walls at the same height position in the pit 1. The support rod 4 can be detachably pressed between the two opposite reinforced purlins 3.

[0028] A plurality of support rods 4 are pressed against two opposite reinforced purlins 3 at the same height. The plurality of support rods 4 at the same height are parallel to each other in the same plane, and the spacings between the plurality of support rods 4 are equal.

[0029] The support rod 4 can be made of steel pipe or steel section. The size of the support rod 4 is determined according to the force calculation. The use specifications have support strength regulations. Technical personnel in this field should be familiar with the calculation method. For safety reasons, a thicker size can be selected. The arrangement of the support rod 4 can be adjusted according to the plane shape of the pit 1 in the pit. The support arrangement should take into account the convenience of earth excavation and transportation operations to avoid the support rod 4 causing obstacles to the continued excavation of the pit 1 in the pit.

[0030] It should be noted that:

[0031] 1. The current support means for the pit in the pit 1 are generally concrete structures, which generally require pile foundation construction. Some are mixing piles, some are cast-in-place piles, and some are cast-in-place concrete walls and panels. All of them require the entire pit to be excavated before the support structure is constructed together. Moreover, these structures require pouring concrete and waiting for it to solidify. The structure takes effect slowly and needs to be waited for. At this time, the pit in the pit 1 is a safety window period, there is no complete and effective support structure, and the construction process is also more troublesome. This device does not need to use concrete, but a full steel structure for support. It can take effect after installation, and there is no need to wait for the concrete to solidify. The side support baffle 2 can be produced after it is tightened. 1. These conventional pit-in-pit 1 support structures all require the use of concrete mixing devices, and some also require larger equipment. When carrying out construction work in a smaller area of ​​a pit-in-pit 1, it is difficult to carry out construction due to insufficient space. This device does not require other large equipment, only a lifting device, which can be an electric hoist, to hoist the side support baffle 2, and then provide support on the side wall of the pit-in-pit 1. It is simple to operate, convenient to construct, and has low equipment requirements; 3. Foundation pit projects generally construct side wall vertical support piles first, and then excavate the foundation pit soil within the side wall, so that the side wall soil will not collapse, rather than digging to the bottom first and then constructing support piles. Conventional pit-in-pit vertical support piles can be constructed on the original ground or on the bottom of the large foundation pit after excavation. This device does not construct side wall vertical branch piles. In order to control the deformation or collapse of the side wall soil of the foundation pit during the excavation stage, the layered excavation and branch height are controlled, and the support layer is excavated one layer at a time.

[0032] When the utility model is used, the method is as follows:

[0033] Step 1: Stake out and locate the sideline of the pit-in-pit 1 of the foundation pit 12 to determine the shape of the excavation range of the pit-in-pit 1;

[0034] Step 2, start excavating the pit 1 in the lofting range at the bottom of the foundation pit 12, control the excavation depth, ensure the stability of the soil layer within the excavation depth range, and then install the first layer, i.e. the uppermost side support baffle 2, or excavate to a set depth. For example, the side support baffle 2 is one meter high. When the pit 1 is excavated to a depth of 1 meter, the side support baffle 2 can be installed.

[0035] There are two construction methods for the side support baffle 2.

[0036] The first method: after the excavation depth of the pit 1 reaches the height of the side support baffle 2, the first layer of the side support baffle 2 is installed;

[0037] The second method is to use the caisson construction method, that is, for relatively soft strata, a pressing method can be adopted, firstly the side support baffle 2 is pressed downward into the soil layer, and then the earthwork within the pressing depth range of the side support baffle 2 is excavated;

[0038] Step 3, install the steel corbels 31 on the first layer of side support baffles 2, then install the reinforced purlins 3 on the steel corbels 31 of the first layer of side support baffles 2, and then clamp the support rods 4 between the two opposite side support baffles 2 of the first layer. The pit 1 is generally square, and the support rods 4 are installed between the opposite side walls on both sides to support the side support baffles 2 tightly.

[0039] Step 4, continue to dig the second layer of earthwork downwards, and then lay out the second layer of side support baffles 2, align and splice the second layer of side support baffles 2 under the first layer of side support baffles 2, and the upper and lower layers of side support baffles 2 need to be spliced ​​in the same vertical plane as much as possible. It is necessary to weld the connecting steel plates 21 at the splicing gap between the second layer of side support baffles 2 and the first layer of side support baffles 2 to ensure that the first and second layers of side support baffles 2 are welded into an integral force-bearing structure. The number of connecting steel plates 21 depends on the horizontal width of the side support baffles 2, and generally the interval between the connecting steel plates 21 does not exceed 1 meter;

[0040] Then, similar to step 3, a steel corbel 31 is welded on the inner side of the side support baffle 2 of the second layer, and a reinforced purlin 3 is erected. Finally, the reinforced purlin 3 on the two opposite side walls of the pit in the pit 1 is supported by the support rod 4;

[0041] Step 5: Repeat the earthwork excavation and installation of supporting steel components. If there is an over-excavation gap behind the side wall support steel plate due to horizontal earthwork over-excavation, fine stone concrete, medium-coarse sand and other materials can be used to fill it;

[0042] Step 6: excavate the earthwork within the depth range of the lowest sealing layer, and construct the sealing layer. The sealing layer 11 is quick-setting concrete, which plays a role in quickly controlling the uplift and deformation of the pit bottom;

[0043] Step 7: Use the side support baffle 2 as the outer formwork of the underground concrete structure to construct the underground concrete structure.

[0044] The inner side described in this device is the indoor structure of the pit after the construction of the pit in the pit 1 is completed, and the outer side refers to the side that is in contact with the external earthwork of the building.

[0045] Although the specific implementation methods of the present invention are described above, those skilled in the art should understand that the specific embodiments described are only illustrative and are not intended to limit the scope of the present invention. Equivalent modifications and changes made by those skilled in the art in accordance with the spirit of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A layered support structure in a pit-in-pit construction process, characterized in that: include: A pit in a pit (1), a side support baffle (2), a reinforced purlin (3) and a support rod (4); The pit-in-pit (1) is a pit excavated downwards at the bottom of a building foundation pit (12); the top of the pit-in-pit (1) is flush with the bottom of the foundation pit (12); and the bottom of the pit-in-pit (1) is a leveling sealing layer (11) formed by pouring concrete; The side support baffle (2) is a flat steel plate, and the side support baffle (2) is against the side wall of the pit-in-pit (1), and the four vertical side walls of the pit-in-pit (1) are vertically arranged and covered with side support baffles (2); The reinforced purlin (3) is a steel straight rod-shaped purlin, and the reinforced purlin (3) is horizontally erected on the inner side of the side support baffle (2), and the outer side of the side support baffle (2) is in contact with the vertical side wall of the pit (1); The support rod (4) is a steel straight rod, and the support rod (4) is clamped between the reinforced purlins (3) on two opposite vertical side walls at the same height position in the pit (1). The support rod (4) can be detachably pressed between the two opposite reinforced purlins (3).

2. A layered support structure in a pit-in-pit construction process according to claim 1, characterized in that: The two ends of the reinforced purlin (3) extend flush with the left and right sides of the side support baffle (2), and a plurality of steel brackets (31) are also provided on the inner side of the side support baffle (2). The supporting surfaces of the steel brackets (31) on the same side support baffle (2) are on the same straight line, and the reinforced purlin (3) is mounted on the inner side of the side support baffle (2) through the steel brackets (31) for stabilization.

3. The layered support structure in the process of pit-in-pit construction according to claim 1, characterized in that: A plurality of support rods (4) are pressed against two of the reinforced purlins (3) facing each other at the same height position; the plurality of support rods (4) at the same height position are parallel to each other in the same plane, and the spacing between the plurality of support rods (4) is equal.

4. The layered support structure in the pit-in-pit construction process according to claim 1, characterized in that: A plurality of the side support baffles (2) are vertically spliced ​​downward and aligned to fit on the vertical side wall of the pit-in-pit (1); a connecting steel plate (21) is welded to the inner side of the side support baffle (2); and the upper and lower adjacent side support baffles (2) are welded to form a vertical integral flat plate structure through the connecting steel plate (21).

5. A layered support structure in a pit-in-pit construction process according to claim 4, characterized in that: The side support baffle (2) is a steel plate with a thickness of not less than 15 mm, and the reinforced purlin (3) and the support rod (4) are steel straight rods.

Images