Construction method based on conversion of super-large foundation pit support

Abstract

The application provides a construction method based on conversion of a super-large foundation pit support, and the construction method comprises the following steps: S1, first soil excavation and first support trestle construction are performed on the pit and the pit side; S2, after the first support trestle on the pit and the pit side reaches the design strength, second support soil excavation and second support construction are performed on the pit side; S3, after the second support on the pit side reaches the design strength, third support and second support soil excavation and support construction are performed on the pit side and the pit; and S4, after the third support on the pit side and the second support soil excavation and support construction on the pit reach the design strength, bottom plate soil excavation and bottom plate construction are performed. According to the weak position and the non-weak position of the foundation pit, different numbers of supports are used for support, compared with a conventional support system, one support in the pit area can be reduced, the overall construction time of the foundation pit is reasonably shortened, surrounding buildings are protected, and the deformation of the foundation pit is effectively reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building construction, in particular to a construction method based on conversion of inner support of super-large foundation pit. BACKGROUND

[0002] With the current city construction speed increasing, the foundation pit excavation area gradually expands, and the construction unit gives the time limit for a project more and more strict. The deep foundation pit engineering with excavation depth of more than 15m and foundation pit area of more than 30,000 square meters is not uncommon. Due to the reasons of deformation control of surrounding environment factors such as subway, pipeline, under-construction project and municipal road, the foundation pit needs to be separated and excavated and basement structure construction, which puts forward higher requirements for foundation pit enclosure design and construction unit. Because the surrounding environment of the foundation pit is increasingly complex, the city underground pipeline, subway facilities and under-construction project are more sensitive to the deformation influence of deep foundation pit construction; in addition, the construction process also involves tight schedule, rush work and other problems, for example: foundation pit earthwork excavation across Spring Festival, college entrance examination, typhoon season and other stop work influencing factors, if the structure bottom plate is not formed during the stop work period, the cumulative deformation of the foundation pit during the stop work period will cause serious influence on the surrounding environment.

[0003] In view of the problems of long construction period, large foundation pit deformation and large influence on surrounding environment of the foundation pit constructed by partition using conventional construction method in the prior art, the technical personnel in the field have been seeking a solution. SUMMARY

[0004] The purpose of the present application is to provide a construction method based on conversion of inner support of super-large foundation pit, to solve the problems of long construction period, large foundation pit deformation and large influence on surrounding environment of the foundation pit constructed by partition using conventional construction method.

[0005] To solve the above technical problems, the present application provides a construction method based on conversion of inner support of super-large foundation pit, which comprises the following steps:

[0006] S1: first earthwork excavation and first support trestle construction are performed on the pit and the pit side;

[0007] S2: after the first support trestle on the pit and the pit side reaches the design strength, the second support earthwork excavation and the second support construction are performed on the pit side;

[0008] S3: after the second support on the pit side reaches the design strength, the third support on the pit side and the second support earthwork excavation and support construction on the pit are performed;

[0009] S4: after the third support on the pit side and the second support earthwork excavation and support construction on the pit reach the design strength, the bottom plate earthwork excavation and bottom plate construction are performed.

[0010] Optionally, in the construction method based on conversion of the super-large foundation pit support, further comprising:

[0011] During the construction process of the underground structure construction stage, the construction process of the underground structure construction stage comprises the following steps:

[0012] S5: After the bottom plate and the force transmission belt are constructed and reach the design strength, the third support at the pit edge and the conversion support beam are removed, and the underground second-floor structure and the support exchange plate belt are backfilled;

[0013] S6: After the underground second-floor structure and the support exchange plate belt are completed and reach the design strength, the second support at the pit edge, the second support inside the pit, and the conversion support beam are removed, and the inclined throw support exchange support is erected;

[0014] S7: After the inclined throw support is erected, the first support at the pit edge, the first support inside the pit, and the conversion support beam are removed, and the underground first-floor structure and the support exchange plate belt are backfilled;

[0015] S8: The underground structure construction is completed.

[0016] Optionally, in the construction method based on conversion of the super-large foundation pit support, in S1, further comprising:

[0017] The first support at different elevations at the pit edge and inside the pit is converted using concrete support, steel support, or a prefabricated concrete support beam.

[0018] Optionally, in the construction method based on conversion of the super-large foundation pit support, the first layer of earthwork is excavated using a large excavation method.

[0019] Optionally, in the construction method based on conversion of the super-large foundation pit support, the second layer of earthwork is excavated using an island excavation method.

[0020] Optionally, in the construction method based on conversion of the super-large foundation pit support, the third layer of earthwork is excavated using a basin excavation method.

[0021] In the construction method based on conversion of the inner support of the super-large foundation pit provided by the application, the construction method comprises the following steps: S1, first soil excavation and first support trestle construction are performed on the pit and the pit edge; S2, after the first support trestle on the pit and the pit edge reaches the design strength, second support soil excavation and second support construction are performed on the pit edge; S3, after the second support on the pit edge reaches the design strength, third support and second support soil excavation and support construction are performed on the pit edge and the pit; and S4, after the third support on the pit edge and the second support soil excavation and support construction on the pit reach the design strength, bottom plate soil excavation and bottom plate construction are performed. According to the conditions of the weak position (for example, the pit edge) and the non-weak position (for example, the pit) of the foundation pit, different numbers of supports are used for support, and the mature reinforced concrete construction technology is used, so that the operation is simple, safe and reliable; compared with the conventional support system, one support in the pit area can be reduced in the construction method, the construction period and the construction cost are greatly saved, the overall construction time of the foundation pit is reasonably shortened, the time-space effect of the foundation pit engineering is reduced, the surrounding buildings are protected, and the deformation of the foundation pit is effectively reduced. BRIEF DESCRIPTION OF DRAWINGS

[0022] The above and other objects, features and advantages of the present disclosure will become more apparent from the following detailed description thereof taken in conjunction with the accompanying drawings, in which like reference characters designate the same components in the exemplary embodiments of the present disclosure.

[0023] Figure 1 is a flow chart of the construction method based on conversion of the inner support of the super-large foundation pit in an embodiment of the present application;

[0024] Figure 2 is a sectional view of the construction method based on conversion of the inner support of the super-large foundation pit in an embodiment of the present application;

[0025] Figure 3 is a schematic view of the bottom plate inverted bracket;

[0026] Figure 4 is a structural schematic view of the connection node of the conversion beam between different support numbers.

[0027] In the drawings:

[0028] 1 - top beam; 2 - concrete surrounding purlin; 3 - support conversion plate belt; 4 - cement-soil mixing pile; 5 - high-pressure rotary jet grouting pile; 6 - bored pile; 7 - plain concrete force transmission belt; 8 - structure bottom protection; 9 - concrete support; 10 - concrete support beam; 11 - column pile; 12 - conversion beam; 13 - support conversion surrounding purlin beam; 14 - basement structure; 15 - inverted concrete bracket; 16 - bottom plate reinforcement; 17 - tieback reinforcement; 18 - concrete bracket reinforcement. DETAILED DESCRIPTION

[0029] The construction method based on the conversion of the inner support of an ultra-large foundation pit according to the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present application will be more apparent according to the following description and claims. It should be noted that the accompanying drawings are very simplified and use non-precise proportions, which are only used to facilitate and clarify the purpose of assisting the description of the embodiments of the present application.

[0030] The present application will now be further described in detail in conjunction with the accompanying drawings. These drawings are all simplified schematic diagrams, which only schematically show the basic structure of the present application, and thus only show the components related to the present application.

[0031] In the description of the present application, it should be understood that the orientations or positional relationships indicated by the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. are based on the orientations or positional relationships shown in the drawings, which are only used for the convenience of describing the present application and simplifying the description, and thus cannot be understood as indicating or implying that the devices or elements indicated must have a particular orientation, be constructed and operated in a particular orientation, and thus cannot be understood as limiting the present application.

[0032] In addition, the terms "first" and "second" are only used for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the technical features indicated. Therefore, the features defined with "first" and "second" can explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0033] In the present application, unless otherwise specifically defined and limited, the terms "mounting", "connection", "connection", "fixing", etc. should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. 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.

[0034] Please refer to Figures 1 to 4 The construction method based on the conversion of the inner support of an ultra-large foundation pit includes the following steps:

[0035] Firstly, a first layer of earthwork excavation and a first layer of support trestle construction are performed in step S1.

[0036] Then, a second layer of support earthwork excavation and a second layer of support construction are performed in step S2 after the first layer of support trestle in the pit and on the pit side reaches the design strength; the second layer of earthwork is excavated in an island mode, and the second layer of support area in the pit is used as counter-pressure earthwork to reduce the deformation of the foundation pit.

[0037] Then, a third layer of support and a second layer of support earthwork excavation and support construction are performed in step S3 after the second layer of support on the pit side reaches the design strength.

[0038] Then, a bottom plate earthwork excavation and a bottom plate construction are performed in step S4 after the third layer of support on the pit side and the second layer of support earthwork excavation and support construction reach the design strength. The bottom plate earthwork excavation is excavated according to the post-pouring zone.

[0039] Steps S1 to S4 are the foundation construction stage. According to the weak position (for example, the pit side) and the non-weak position (for example, the pit inside) of the foundation pit, different numbers of supports are used for support, and mature reinforced concrete construction technology is used, which is simple to operate, safe and reliable. Compared with the conventional support system, the construction method can reduce one layer of support in the pit area, greatly save the construction period and construction cost, reasonably shorten the overall construction time of the foundation pit, reduce the "time-space effect" of the foundation pit engineering, protect the surrounding buildings and structures, and effectively reduce the deformation of the foundation pit.

[0040] Preferably, in the construction method, the first layer of earthwork is excavated in a large excavation mode; the second layer of earthwork is excavated in an island excavation mode; and the third layer of earthwork is excavated in a basin excavation mode, so as to reduce the deformation of the foundation pit caused by the excavation of the foundation pit.

[0041] Further, the construction method based on the support conversion in the super-large foundation pit further comprises a construction process in a underground structure construction stage; the construction process in the underground structure construction stage comprises the following steps:

[0042] S5: after the bottom plate and the force transmission belt are constructed and reach the design strength, the third layer of support on the pit side and the conversion support beam are removed, and the underground second layer structure and the support exchange plate belt are constructed;

[0043] S6: after the underground second layer structure and the support exchange plate belt are completed and reach the design strength, the second layer of support on the pit side, the second layer of support in the pit and the conversion support beam are removed, and the inclined throw support exchange support is erected.

[0044] S7: After the completion of the inclined throwing support frame, the first support at the pit edge, the first support inside the pit and the removal of the conversion support beam are carried out, and the first underground structure and the conversion support plate belt are rebuilt;

[0045] S8: The underground structure construction is completed.

[0046] Please refer to Figure 2 and Figure 4 , Figure 2 The cross-sectional view shows the structural level distribution of the first underground floor and the second underground floor; Figure 4 The structural diagram of the conversion beam connection node between different support channels is shown, Figure 2 The cross-sectional view includes: the pressure top beam 1, the concrete surrounding purlin 2, the conversion support plate belt 3, the cement-soil mixing pile 4, the high-pressure rotary jet pile 5, the cast-in-place pile 6, the plain concrete force transmission belt 7, the structural bottom protection 8, the concrete support 9, the concrete support beam 10, the column pile 11, the conversion beam 12, the support conversion surrounding purlin beam 13, and since Figure 2 It is to show the position and number of supports set by the construction method, Figure 4 It is to show the structure of the conversion beam connection node between different support channels, the position and connection relationship between each structure please refer to Figure 2 and Figure 4 , which will not be described in detail here.

[0047] Please refer to Figure 3 , which is a schematic diagram of the bottom plate under the inverted bracket, specifically including: the inverted concrete bracket 15, the bottom plate reinforcement 16, the tie bar 17 and the concrete bracket reinforcement 18, their positions and relationships please refer to Figure 3 , based on the design of the bottom plate under the inverted bracket, the connection is effectively enhanced, the load is dispersed, the deformation is adapted, and the construction is facilitated, thereby ensuring the stability and safety of the structure.

[0048] It should be noted that for the foregoing method embodiments, in order to simply describe, they are all expressed as a series of action combinations, but those skilled in the art should know that the application is not limited by the described action sequence, because according to the application, certain steps can be performed in other order or simultaneously. Secondly, those skilled in the art should know that the embodiments described in the specification all belong to preferred embodiments, and the actions and modules involved are not necessarily required by the application.

[0049] In the above embodiments, the description of each embodiment has its own emphasis, and the parts not described in detail in a certain embodiment can be referred to the relevant description of other embodiments.

[0050] In summary, in the construction method based on the conversion of the super-large foundation pit support provided by the application, the construction method comprises: S1: first soil excavation and first support trestle construction are performed on the pit and the pit side; S2: after the first support trestle on the pit and the pit side reaches the design strength, second support soil excavation and second support construction are performed on the pit side; S3: after the second support on the pit side reaches the design strength, third support and second support soil excavation and support construction are performed on the pit side and the pit; and S4: after the third support on the pit side and the second support soil excavation and support construction on the pit reach the design strength, bottom plate soil excavation and bottom plate construction are performed. According to the conditions of the weak position (for example, the pit side) and the non-weak position (for example, the pit) of the foundation pit, different numbers of supports are used for support, and the mature reinforced concrete construction technology is used, which is simple to operate, safe and reliable. Compared with the conventional support system, one support in the pit area can be reduced in the construction method, the construction period and the construction cost are greatly saved, the overall construction time of the foundation pit is reasonably shortened, the time-space effect of the foundation pit engineering is reduced, the surrounding buildings are protected, and the deformation of the foundation pit is effectively reduced.

[0051] The above description is only a description of the preferred embodiments of the application, and does not limit the scope of the application in any way. Any modification or change made by a person skilled in the art according to the above disclosure is within the protection scope of the claims.

Claims

1. A construction method based on conversion of a super-large foundation pit support, characterized in that, The method comprises the following steps: S1: first soil excavation and first support trestle construction are performed on the pit and the pit edge, and concrete supports or steel supports are used to convert the first supports of different elevations on the pit edge and the pit; S2: after the first support trestle on the pit edge and the pit reaches the design strength, the second support soil excavation and the second support construction on the pit edge are performed; S3: after the second support on the pit edge reaches the design strength, the third support on the pit edge and the second support soil excavation and support construction on the pit are performed; the second support on the pit edge, the third support on the pit edge and the second support on the pit are converted through a conversion support beam; S4: after the third support on the pit edge and the second support soil excavation and support construction on the pit reach the design strength, the bottom plate soil excavation and the bottom plate construction are performed; The method further comprises a construction process in a construction stage of an underground structure; the construction process in the construction stage of the underground structure comprises the following steps: S5: after the bottom plate and the force transmission belt are constructed and reach the design strength, the third support on the pit edge and the conversion support beam are removed, and the underground second-floor structure and the support exchange plate belt are constructed; S6: after the underground second-floor structure and the support exchange plate belt are constructed and reach the design strength, the second support on the pit edge, the second support on the pit and the conversion support beam are removed, and the inclined throw support exchange support is erected; S7: after the inclined throw support is erected, the first support on the pit edge, the first support on the pit and the conversion support beam are removed, and the underground first-floor structure and the support exchange plate belt are constructed; S8: the construction of the underground structure is completed.

2. The construction method based on conversion of the super-large foundation pit support according to claim 1, characterized in that, The first layer of soil is excavated in a large excavation mode.

3. The construction method based on conversion of an extra-large foundation pit support according to claim 1, characterized in that, The second layer of soil is excavated in an island excavation mode.

4. The construction method based on conversion of an extra-large foundation pit support according to claim 1, characterized in that, The third layer of soil is excavated in a basin excavation mode.

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