阅读说明：本技术 在既有保留建筑下方原位开挖基坑及新增地下结构的方法 (Method for in-situ excavation of foundation pit and new addition of underground structure under existing reserved building ) 是由 贾坚 翟杰群 谢小林 蓝戊己 章柏林 吴洁妹 董恒晟 朱敏峰 杨科 张志彬 方银 于 2019-11-01 设计创作，主要内容包括：本发明涉及一种在既有保留建筑下方原位开挖基坑及新增地下结构的方法。根据新建基坑施工所需地面作业场地与既有保留建筑的位置关系分别确定顶升托换建筑体和原位托换建筑体,在顶升托换建筑体下方施工顶升托换结构、在原位托换建筑体下方施工原位托换结构；顶升托换建筑体抬升至预设高度后,顶升托换结构下表面设置的支承结构与顶升托换结构共同形成架空结构,架空结构下方提供较大的施工空间,方便在建筑物旁边施工深基坑围护结构以及施工深基坑,在形成的基坑主体中设置地下结构。本发明适用于既有保留建筑下方实施基坑施工和地下空间开发,不会对既有保留建筑造成损伤,不要求建筑原址附近周边有较大的场地进行施工,施工难度和成本显著下降。(The invention relates to a method for excavating a foundation pit and adding an underground structure in situ below an existing reserved building. Respectively determining a jacking underpinning building body and an in-situ underpinning building body according to the position relation between a ground operation field required by the construction of a newly-built foundation pit and an existing reserved building, constructing a jacking underpinning structure below the jacking underpinning building body, and constructing an in-situ underpinning structure below the in-situ underpinning building body; after the jacking underpinning building body is lifted to the preset height, a supporting structure arranged on the lower surface of the jacking underpinning structure and the jacking underpinning structure form an overhead structure together, a larger construction space is provided below the overhead structure, the deep foundation pit support structure and the deep foundation pit can be conveniently constructed beside the building, and an underground structure is arranged in a formed foundation pit main body. The invention is suitable for implementing foundation pit construction and underground space development under the existing reserved building, can not damage the existing reserved building, does not require a larger field around the original site of the building for construction, and obviously reduces the construction difficulty and cost.)

1. A method of excavating a foundation pit in situ below an existing retaining structure, comprising:

respectively determining a jacking underpinning building body and an in-situ underpinning building body according to the position relation between a ground operation field required by the construction of a newly-built foundation pit and an existing reserved building;

constructing a underpinning pile foundation in a soil layer, wherein the underpinning pile foundation is distributed around the jacking underpinning building body and the in-situ underpinning building body;

respectively constructing a jacking underpinning structure below the jacking underpinning building body and constructing an in-situ underpinning structure below the in-situ underpinning building body;

jacking the jacking underpinning structure and the jacking underpinning building body to a preset height, and arranging a supporting structure on the lower surface of the jacking underpinning structure, so that the supporting structure and the jacking underpinning structure together form an overhead structure for supporting the jacking underpinning building body; constructing a foundation pit enclosure structure in the space below the overhead structure;

constructing the foundation pit main body of the newly-built foundation pit in the space below the overhead structure, wherein the in-situ underpinning structure provides a first horizontal support for the foundation pit main body, and the underpinning pile foundation provides a vertical support for a horizontal support system of the foundation pit main body, so that the in-situ underpinning structure and the underpinning pile foundation jointly provide a three-dimensional support for the foundation pit main body.

2. The method of in situ excavation of a foundation pit beneath an existing structure of claim 1, wherein the separately identifying the jacking and in situ underpinning structures based on the positional relationship between the ground work site required for construction of the newly created foundation pit and the existing structure of the existing structure comprises: and determining the building arranged in the ground operation field required by the construction of the newly-built foundation pit as the jacking underpinning building body, and determining the buildings positioned outside the ground operation field required by the construction of the newly-built foundation pit as the in-situ underpinning building body.

3. The method of in situ excavation of a foundation pit under an existing retaining structure of claim 2, wherein the ground work area required for the construction of the newly created foundation pit includes ground work spaces such as foundation pit support structure construction, construction of engineering piles and foundation reinforcement, construction equipment driving routes and work areas, construction yards, foundation pit excavation outlets, and the like.

4. The method of in situ excavation of a foundation pit beneath an existing retaining structure of claim 1, wherein the underpinning pile foundation is constructed into the earth strata and is at least one of a cast-in-place pile, a steel pipe pile and a static pressure anchor pile when the underpinning pile foundation is outside the newly created foundation pit.

5. The method of in-situ excavation of a foundation pit under an existing retaining building according to claim 1, wherein the underpinning pile foundation is constructed into the soil layer, when the underpinning pile foundation is located within the newly constructed foundation pit and the construction space is narrow, a static pressure anchor pile is constructed into the soil layer of the newly constructed foundation pit in advance, and after the overhead structure is formed, a cast-in-place pile or a steel pipe pile is constructed in the space under the overhead structure to replace the static pressure anchor pile.

6. The method of in situ excavation of a foundation pit beneath an existing retaining structure of claim 1, wherein the underpinning pile foundation is constructed into the soil layer and is a cast-in-place pile or a steel pipe pile when the underpinning pile foundation is located within the newly constructed foundation pit and the construction space is sufficient.

7. The method of in situ excavation of a foundation pit under an existing retaining structure of claim 1, wherein the jacking underpinning structure is a beam slab structure or a slab structure.

8. The method of excavating a foundation pit in situ below an existing retaining structure of claim 1, wherein the in situ underpinning structure is a beam slab structure or a slab structure.

9. The method of excavating a foundation pit in situ below an existing retaining structure of claim 1, wherein the support structure is a support column.

10. The method of excavating a foundation pit in situ below an existing retaining structure of claim 9, wherein the support columns are reinforced concrete columns, steel core concrete columns, steel columns, or steel reinforced columns.

11. A method of adding a subterranean formation to an existing structure below the existing structure, comprising the method of excavating a foundation pit in situ below the existing structure as claimed in any one of claims 1 to 10 and providing the subterranean formation in the formed body of the foundation pit, the providing of the subterranean formation in the formed body of the foundation pit comprising:

building an underground structure in the foundation pit main body;

and operating the jacking underpinning structure and the jacking underpinning building body to fall back to the required position.

12. A method of retrofitting an underground structure below an existing retaining building according to claim 11 wherein the underground structure is formed using either a cover and dig forward or reverse approach.

Technical Field

The invention relates to the field of building construction, in particular to a method for excavating a foundation pit and adding an underground structure in situ below an existing reserved building.

Background

Existing reserved buildings (including history reserved buildings, cultural buildings, buildings in the protected landscape areas and other types of buildings which cannot be dismantled) are important carriers of city history, art and culture, so that the urban buildings are more and more valued by urban managers; meanwhile, with the development of cities, underground spaces are also more fully developed. In the development and construction of the underground space of modern cities, the organic combination of the existing reserved building and the newly added underground structure is emphasized, so that the use function of the existing reserved building which is long in the past can be improved by means of the development of the underground space, and the existing reserved building is suitable for the development requirement of the times. The excavation of the foundation pit in situ under the existing reserved building so as to build an underground space under the existing reserved building is a difficult problem of city updating and reconstruction, but is also a future trend.

In the past, the following methods are mainly adopted for excavating foundation pits below the existing buildings:

1. the disassembling method comprises the following steps: and if the existing building is not the reserved building, directly dismantling the original building and then newly building an underground structure. The method is the same as the construction of a foundation pit on the open ground, the process is mature, and the manufacturing cost is lower. But this method cannot be applied if the existing building belongs to a history reserved building, a cultural relic building, a building of a feature protected area, and other types of existing reserved buildings that cannot be dismantled.

2. A translation method: and if the site conditions allow, translating the existing building to other places, then newly building an underground structure on the open space of the original site of the building, and translating the existing building back to the original site after the newly built underground structure is completed. The method can integrally reserve the original building, but the premise is that enough fields near the original site of the reserved building are needed to perform translation operation. If the translation of the existing reserved buildings with four sides tightly attached to a red land line has insufficient empty space or the translation turnover cost of the existing reserved buildings is too high, the method is not applicable.

3. Traditional in-situ underpinning: the method adopts a static pressure anchor rod pile to underpin an original building foundation, and then a foundation pit is dug below the static pressure anchor rod pile. The method has the following limitations: because the indoor clearance of the original building is low, the indoor space can only be used for operating small equipment such as a static pressure anchor rod pile, a small excavator and the like, and large equipment needs to be operated outdoors; especially in saturated soft soil areas, when a foundation pit is deep, necessary large-scale equipment for deep foundation pit construction such as underground continuous wall grooving equipment, large-scale steel reinforcement cage hoisting equipment, a long-arm excavator and the like is often needed, the process equipment cannot be constructed in the internal space of an existing building, so that sufficient open space is required to be reserved beside the building for operation, and meanwhile, a deep foundation pit support structure such as an underground continuous wall and the like must be arranged on the outer side of the existing building, so that the large-scale excavator, an earth moving vehicle and the like must be arranged outside the existing building room, otherwise, the foundation pit cannot be implemented below the building, and the method is difficult to solve the problem of construction work site when facing the existing reserved building; if the construction is carried out only in a narrow indoor space, small-scale shallow-depth foundation pit construction can be carried out only by small equipment, and large-scale deep foundation pit construction cannot be carried out.

Disclosure of Invention

Therefore, it is necessary to provide a method for excavating a foundation pit in situ below an existing reserved building and adding an underground structure to the existing reserved building in order to solve the problem that when the foundation pit is excavated below the existing building, there is not enough space around the existing reserved building to perform deep foundation pit construction operation.

A method of excavating a foundation pit in situ below an existing retaining structure, comprising:

respectively determining a jacking underpinning building body and an in-situ underpinning building body according to the position relation between a ground operation field required by the construction of a newly-built foundation pit and an existing reserved building;

constructing a underpinning pile foundation in a soil layer, wherein the underpinning pile foundation is distributed around the jacking underpinning building body and the in-situ underpinning building body;

respectively constructing a jacking underpinning structure below the jacking underpinning building body and constructing an in-situ underpinning structure below the in-situ underpinning building body;

jacking the jacking underpinning structure and the jacking underpinning building body to a preset height, and arranging a supporting structure on the lower surface of the jacking underpinning structure, so that the supporting structure and the jacking underpinning structure together form an overhead structure for supporting the jacking underpinning building body; constructing a foundation pit enclosure structure in the space below the overhead structure;

constructing a foundation pit main body of the newly-built foundation pit in the space below the overhead structure, wherein the in-situ underpinning structure provides a first horizontal support for the foundation pit main body, and the underpinning pile foundation provides a vertical support for a horizontal support system of the foundation pit main body, so that the in-situ underpinning structure and the underpinning pile foundation jointly provide a three-dimensional support for the foundation pit main body.

The method for excavating the foundation pit in situ below the existing reserved building at least has the following beneficial technical effects:

(1) after the jacking underpinning structure and the jacking underpinning building body are lifted to the preset height, the supporting structure arranged on the lower surface of the jacking underpinning structure and the jacking underpinning structure form an overhead structure together, a large construction operation space can be provided below the overhead structure, large-scale equipment can be arranged below the overhead structure, and the deep foundation pit support structure can be conveniently constructed beside a building and large-scale deep foundation pit construction can be realized below the existing reserved building. Still can set up the yard, the driving route and the operation area of main equipment, foundation ditch excavation unearthed mouthful etc. during the construction of foundation ditch main part in the below of overhead structure, the below space of overhead structure is great for the construction method is more with nimble convenient.

(2) The method is suitable for implementing foundation pit construction and underground space development under the existing reserved building, cannot damage the existing reserved building, does not require a larger field around the original site of the building for construction compared with a translation method and a traditional in-situ underpinning method, and obviously reduces the construction difficulty and cost;

(3) the in-situ underpinning structure can provide a first horizontal support for the foundation pit main body during construction of the foundation pit main body, so that the horizontal support degree of the foundation pit main body is ensured, and the underpinning pile foundation serves as a vertical support upright post of the foundation pit main body to provide a vertical support for a horizontal support system of the foundation pit, so that the in-situ underpinning structure and the underpinning pile foundation together provide a three-dimensional support for the foundation pit main body; the in-situ underpinning structure can also be used as a foundation pit main body and a top plate of a later-stage newly-built underground structure, so that the foundation pit main body is prevented from collapsing due to the fact that excessive pressure is generated on the foundation pit main body by an existing reserved building, and construction and use safety is guaranteed.

(4) The jacking underpins the structure and both can stably bear the jacking underpins the building body in the jacking process, guarantee the safety of construction, the construction finishes to operate its fall back can regard as the roof of the newly-built underground structure of foundation ditch main part and later stage after the position requires, avoids existing reservation building to produce too big pressure to the foundation ditch main part and leads to the foundation ditch main part to collapse, has guaranteed construction and safe in utilization.

In one embodiment, the determining the jacking underpinning building body and the in-situ underpinning building body according to the position relationship between the ground operation field required by the construction of the newly-built foundation pit and the existing reserved building respectively comprises: and determining the building arranged in the ground operation field required by the construction of the newly-built foundation pit as the jacking underpinning building body, and determining the buildings positioned outside the ground operation field required by the construction of the newly-built foundation pit as the in-situ underpinning building body.

In one embodiment, the ground operation sites required by the construction of the newly-built foundation pit comprise ground operation spaces such as construction of a foundation pit enclosure structure, construction of engineering piles and foundation reinforcement, a construction equipment driving route and an operation area, a construction yard, a foundation pit excavation soil outlet and the like.

In one embodiment, the underpinning pile foundation is constructed into the soil layer, and when the underpinning pile foundation is positioned outside the newly-built foundation pit, the underpinning pile foundation is at least one of a cast-in-place pile, a steel pipe pile and a static pressure anchor pile.

In one embodiment, the underpinning pile foundation is constructed into the soil layer, when the underpinning pile foundation is positioned in the newly-built foundation pit and the construction space is narrow, a static pressure anchor pile is constructed into the soil layer of the newly-built foundation pit in advance, and after the overhead structure is formed, a cast-in-place pile or a steel pipe pile is constructed in the space below the overhead structure to replace the static pressure anchor pile.

In one embodiment, the underpinning pile foundation is constructed into the soil layer, and when the underpinning pile foundation is positioned in the newly-built foundation pit and the construction space is sufficient, the underpinning pile foundation is a cast-in-place pile or a steel pipe pile.

In one embodiment, the jacking underpinning structure is a beam slab structure or a thick slab structure.

In one embodiment, the in-situ underpinning structure is a beam slab structure or a thick slab structure.

In one embodiment, the support structure is a support column.

In one embodiment, the support column is a steel reinforced concrete column, a steel core concrete column, a steel column or a steel reinforced column.

A method of adding an underground structure below an existing reserved building, comprising a method of excavating a foundation pit in situ below the existing reserved building and providing the underground structure in a formed foundation pit body, wherein providing the underground structure in the formed foundation pit body comprises:

building an underground structure in the foundation pit main body;

and operating the jacking underpinning structure and the jacking underpinning building body to fall back to the required position.

(1) The method is suitable for implementing foundation pit excavation and underground space development under the existing reserved building. Compared with a translation method and a traditional in-situ underpinning method, the method does not require a larger site near the original site of the building for construction, and construction difficulty and cost are obviously reduced.

(2) The in-situ underpinning structure can provide a first horizontal support for the foundation pit main body during construction of the foundation pit main body, so that the horizontal support degree of the foundation pit main body is ensured, and the underpinning pile foundation serves as a vertical support upright post of the foundation pit main body to provide a vertical support for a horizontal support system of the foundation pit, so that the in-situ underpinning structure and the underpinning pile foundation together provide a three-dimensional support for the foundation pit main body; the in-situ underpinning structure can also be used as a top plate of the newly-added underground structure, so that the underground structure is prevented from collapsing due to the fact that excessive pressure is generated on the newly-added underground structure by the existing retaining building, and construction and use safety is guaranteed.

(3) The jacking underpinning structure can stably support the jacking underpinning building body in the jacking process, the construction safety is guaranteed, the jacking underpinning structure can be used as a top plate of an underground structure after the construction is finished and the jacking underpinning structure falls back to a required position, the phenomenon that the newly added underground structure collapses due to the fact that excessive pressure is generated on the newly added underground structure by the reserved building is avoided, and the construction and use safety is guaranteed.

In one embodiment, the underground structure is formed by a cover and dig forward or reverse method.

Drawings

FIG. 1 is a schematic plan view of a jacking underpinning building body and an in-situ underpinning building body determined in a method for in-situ excavation of a foundation pit under an existing reserved building according to an embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;

FIG. 3 is a schematic plan view of a method of excavating a pit in situ beneath an existing retaining structure, in accordance with an embodiment of the present invention, for constructing a underpinning pile foundation into the earth formation;

FIG. 4 is a cross-sectional view taken along line B-B of FIG. 3;

FIG. 5 is a schematic plan view of a construction jacking underpinning structure and an in-situ underpinning structure in a method for in-situ excavation of a foundation pit under an existing reserved building according to an embodiment of the present invention;

FIG. 6 is a cross-sectional view taken at C-C of FIG. 5;

FIG. 7 is a schematic illustration of the jacking underpinning structure and jacking underpinning structure of FIG. 6 being jacked up;

fig. 8 is a schematic plan view of the formation of an overhead structure below a jacking replacement building body and the construction of a foundation pit enclosure in the space below the overhead structure in a method of excavating a foundation pit in situ below an existing reserved building according to an embodiment of the present invention;

FIG. 9 is a cross-sectional view taken at D-D of FIG. 8;

fig. 10 is a schematic view illustrating a construction of a foundation pit main body in a space below an overhead structure in a method of excavating a foundation pit in situ under an existing reserved building according to an embodiment of the present invention;

fig. 11 is a schematic diagram of a method for adding an underground structure below an existing reserved building according to an embodiment of the present invention.

In the figure: 100. newly building a foundation pit, excavating sidelines and 110, a foundation pit main body and 111, horizontally supporting and 120, a foundation pit enclosure structure,

200. the method comprises the steps of reserving a building, 210 jacking and underpinning the building, 220 in-situ underpinning the building,

300. an overhead structure, 310, a jacking and underpinning structure, 320, a supporting structure,

400. the in-situ underpinning structure is provided with a plurality of support plates,

500. the pile foundation is underpinned and replaced,

600. an underground structure.

Detailed Description

The invention will be further explained with reference to the drawings.

To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Those of ordinary skill in the art will recognize that variations and modifications of the various embodiments described herein can be made without departing from the scope of the invention, which is defined by the appended claims. Moreover, descriptions of well-known functions and constructions may be omitted for clarity and conciseness.

It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present; when an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

As shown, in one embodiment of the present invention, there is provided a method for excavating a pit in situ below an existing retaining structure, comprising:

referring to fig. 1 and 2, according to the position relationship between the newly-built foundation pit 100 and the existing reserved building 200, and in combination with the construction organization, the jacking underpinning building 210 and the in-situ underpinning building 220 are respectively determined, i.e. the range of jacking underpinning and in-situ underpinning of the existing reserved building 200 is divided;

referring to fig. 3 and 4, the underpinning pile foundation 500 is constructed into the soil layer, and the underpinning pile foundation 500 is laid around the jacking underpinning building body 210 and the in-situ underpinning building body 220;

referring to fig. 5 and 6, a jacking underpinning structure 310 is constructed below the jacking underpinning building body 210 and an in-situ underpinning structure 400 is constructed below the in-situ underpinning building body 220, respectively;

referring to fig. 7, the jacking underpinning structure 310 and the jacking underpinning building body 210 are jacked up to a preset height by using a jacking device such as a jack; referring to fig. 8 and 9, a support structure 320 is provided on the lower surface of the jacking underpinning structure 310, so that the support structure 320 and the jacking underpinning structure 310 cooperate to form an overhead structure 300 for supporting the jacking underpinning building body 210, and the construction of the foundation pit enclosure 120 is performed in the space below the overhead structure 300;

referring to fig. 10, a foundation pit main body 110 is constructed in a space below an overhead structure 300, and a plurality of horizontal supports 111 may be sequentially arranged as the excavation depth of the foundation pit increases during construction; the in-situ underpinning structure 400 can be used as a first horizontal support of the foundation pit main body 110, and the underpinning pile foundation 500 is used as a vertical support column of the foundation pit main body 110 to provide a vertical support for a horizontal support system of the foundation pit, so that the in-situ underpinning structure 400 and the underpinning pile foundation 500 together provide a three-dimensional support for the foundation pit main body 110.

The foundation pit enclosure 120 may be specifically an engineering pile, and in some embodiments, the foundation pit enclosure 120 may be disposed along the excavation boundary line 101. The construction of the foundation pit main body 110 may specifically include foundation pit support and earth excavation, and in fig. 10, when the construction of the foundation pit main body 110 is performed in the space below the overhead structure 300, a yard, a driving route of large equipment, a foundation pit excavation soil outlet, and the like during the construction of the foundation pit main body 110 may be provided below the overhead structure 300.

After the jacking underpinning structure 310 and the jacking underpinning building body 210 are lifted to the preset height, the supporting structure 320 arranged on the lower surface of the jacking underpinning structure 310 and the jacking underpinning structure 310 form the overhead structure 300 together, a larger construction operation space can be provided below the overhead structure 300, large-scale equipment can be arranged below the overhead structure 300, the foundation pit support structure 120 can be conveniently constructed beside a building, and a deep foundation pit can be conveniently constructed on a large scale below the existing retaining building. And a storage yard, a traveling route of large equipment, a foundation pit excavation soil outlet and the like during construction of the foundation pit main body 110 can be arranged below the overhead structure 300, and the space below the overhead structure 300 is large, so that the construction mode is more flexible and convenient.

The method is particularly suitable for implementing large-scale foundation pit construction and underground space development below the existing reserved building in a sheet form, but also can be applied to underground space development of the existing reserved building in a non-sheet form. Compared with a translation method and a traditional in-situ underpinning method, the method of the invention does not require sufficient fields around the original site of the building for construction, and the construction difficulty and cost are obviously reduced;

the in-situ underpinning structure 400 can provide a first horizontal support for the foundation pit main body 110 during the construction of the foundation pit main body 110, so that the horizontal support degree of the foundation pit main body 110 is ensured, the underpinning pile foundation 500 serves as a vertical support column of the foundation pit main body 110 to provide vertical support for a horizontal support system of the foundation pit, and thus the in-situ underpinning structure 400 and the underpinning pile foundation 500 together provide a three-dimensional support for the foundation pit main body 110; the in-situ underpinning structure 400 can also be used as a top plate of the foundation pit main body 110 and an underground structure 600 newly built at a later stage, so that the foundation pit main body 110 is prevented from collapsing due to the fact that excessive pressure is generated on the foundation pit main body 110 by existing reserved buildings, and construction and use safety is guaranteed.

The jacking underpinning structure 310 can stably support the jacking underpinning building body in the jacking process, the construction safety is guaranteed, the jacking underpinning structure can be used as a top plate of the foundation pit main body 110 and a later-stage newly-built underground structure 600 after the construction is finished and the jacking underpinning structure falls to a required position, the problem that the foundation pit main body 110 collapses due to the fact that excessive pressure is generated on the foundation pit main body 110 by existing reserved buildings is avoided, and the construction and use safety is guaranteed.

Referring to fig. 1, 2, 8 and 9, in some embodiments, the jacking underpinning building 210 and the original underpinning building 220 are determined according to the position relationship between the ground operation field required by the newly-built foundation pit construction and the existing reserved building 200, in this embodiment, the ground operation field required by the newly-built foundation pit construction is located in the ground area right above the foundation pit enclosure structure 120, so that the building placed on the foundation pit enclosure structure 120 is determined as the jacking underpinning building 210, the building not placed on the foundation pit enclosure structure 120 is determined as the original underpinning building 220, and since the foundation pit enclosure structure 120 is disposed along the excavation sideline 101 of the newly-built foundation pit 100, the building placed on the excavation 101 is set as the jacking underpinning building 210 before construction. The building contacted with the excavation edge line 101 of the newly-built foundation pit 100 is jacked up, so that the overhead structure 300 formed after jacking is positioned at the edge of the newly-built foundation pit 100, a construction operation space of the foundation pit support structure 120 is formed, the space can also be used as a foundation pit excavation soil outlet operation area in the future, and convenience is provided for deep foundation pit construction operation.

It is understood that in other embodiments, other methods may be used to determine the jacking underpinning building body 210 and the in-situ underpinning building body 220, for example, a construction site often needs to set up a necessary working area such as a driving and operating area of construction equipment, a construction yard, etc., and an existing reserved building in the working area may be set as the jacking underpinning building body 210, and after jacking the jacking underpinning building body, the working area necessary for construction may be provided.

In some embodiments, the underpinning pile foundation 500 is constructed into the soil layer, and when the underpinning pile foundation 500 is located outside the newly-built foundation pit 100, the underpinning pile foundation 500 can be in any one of a cast-in-place pile, a steel pipe pile or a static pressure anchor pile according to choice since the underpinning pile foundation 500 outside the foundation pit does not affect the subsequent construction of the foundation pit main body 110 and the foundation pit support structure 120.

In some embodiments, the underpinning pile foundation 500 is constructed in a soil layer, when the underpinning pile foundation 500 is located in the newly-built foundation pit 100, the underpinning pile foundation 500 is required to be used as a vertical supporting upright of the foundation pit main body 110 during construction of the later-stage foundation pit support structure 120 and the foundation pit main body 110, so that the underpinning pile foundation 500 is required to have high bearing capacity, the underpinning pile foundation 500 can be a cast-in-place pile or a steel pipe pile, and the cast-in-place pile or the steel pipe pile has high bearing capacity and can meet the subsequent construction safety requirement. However, the cast-in-place pile or the steel pipe pile needs a larger construction space, so when the construction space is narrow and small and the cast-in-place pile or the steel pipe pile cannot be developed, the static pressure anchor pile can be adopted as the underpinning pile foundation 500, but the bearing capacity of the static pressure anchor pile is smaller, the number of pile foundations required under the same load condition is larger, if the static pressure anchor pile is arranged too densely, the subsequent foundation pit excavation operation and the construction action of large equipment can be directly influenced, the static pressure anchor pile can be constructed in the soil layer in advance in order to solve the problem, after the overhead structure 300 is formed, the static pressure anchor pile is replaced by the cast-in-place pile in the space construction below.

In this embodiment, after the method is adopted, the static pressure anchor rod pile can be used as the underpinning pile foundation 500 to provide vertical support before the construction jacking underpinning structure 310 and the in-situ underpinning structure 400 are formed, and the static pressure anchor rod pile can be replaced by the filling pile with a large distance before the foundation pit main body 110 is constructed so as to meet the requirements of subsequent foundation pit excavation operation and construction action of large-scale equipment, so that the vertical support requirement is ensured, and the construction operation of the foundation pit main body 110 is not influenced.

In some embodiments, the jacking underpinning structure 310 is a beam slab structure or a thick slab structure, and the beam slab structure or the thick slab structure has sufficient rigidity to stably support and support the jacking underpinning building body 210 after jacking the jacking underpinning building body 210, so as to ensure the safety of the jacking underpinning building body 210 during construction.

In some embodiments, the in-situ underpinning structure 400 is a beam slab structure or a slab structure. The in-situ underpinning structure 400 is a first horizontal support of the foundation pit main body 110 and also needs to be used as a top plate of the newly-added underground structure 600, so that enough strength and support property need to be ensured, and the selected beam plate structure or thick plate structure has better rigidity and can meet the use requirement.

Referring to fig. 9, in some embodiments, the support structure 320 is a support post. Preferably, the support column is a reinforced concrete column, a steel tube concrete column, a steel column or a steel reinforced column. The reinforced concrete column, the steel pipe concrete column, the steel column or the steel stiffness column have enough strength and support performance, and can stably support and support the jacking underpinning building body 210, so that the safety of the jacking underpinning building body 210 during construction is guaranteed.

In the present invention, after the jacking underpinning building body 210 is jacked up, the jacking underpinning structure 310 needs to maintain a sufficient clearance height to the ground, and the adjacent support columns need to ensure a sufficient distance to meet the requirement of the subsequent large-scale equipment construction operation.

In another embodiment of the present invention, a method for adding an underground structure 600 below an existing reserved building 200 is provided, which includes the above method for excavating a foundation pit in situ below the existing reserved building 200 and further providing the underground structure 600 in the formed foundation pit body 110. Referring to fig. 11, the setting of the underground structure 600 in the formed foundation pit body 110 specifically includes: constructing an underground structure 600 in the formed foundation pit body 110; the jacking device such as a jack or a hydraulic oil cylinder is arranged below the jacking underpinning structure 310, the jacking device is operated to descend after the supporting structure 320 is removed, the jacking device synchronously drives the jacking underpinning structure 310 and the jacking underpinning building body 210 to fall back to a required position when descending, at the moment, both the jacking underpinning structure 310 and the in-situ underpinning structure 400 can be used as a top plate of the newly-added underground structure 600, the phenomenon that the newly-added underground structure 600 collapses due to the fact that excessive pressure is generated on the newly-added underground structure 600 by the existing reserved building 200 is avoided, and therefore use safety is guaranteed. The jacking device synchronously drives the jacking underpinning structure 310 and the jacking underpinning building body 210 to fall back to the required position when descending, and the jacking underpinning structure and the jacking underpinning building body can fall back to the initial height, or can not fall back to the initial height, but are combined with the overall layout of the project to adjust the height mark of the fall back.

The method is suitable for implementing foundation pit excavation and underground space development under the existing reserved building. Compared with a translation method and a traditional in-situ underpinning method, the method does not cause damage to the existing reserved building, does not require a larger field around the original site of the building for construction, and obviously reduces the construction difficulty and cost.

The in-situ underpinning structure 400 can provide a first horizontal support for the foundation pit main body 110 during the construction of the foundation pit main body 110, so that the horizontal support degree of the foundation pit main body 110 is ensured, the underpinning pile foundation 500 serves as a vertical support column of the foundation pit main body 110 to provide vertical support for a horizontal support system of the foundation pit, and thus the in-situ underpinning structure 400 and the underpinning pile foundation 500 together provide a three-dimensional support for the foundation pit main body 110; the in-situ underpinning structure 400 can also be used as a top plate of the newly-added underground structure 600, so that the underground structure 600 is prevented from collapsing due to the fact that excessive pressure is generated on the newly-added underground structure 600 by the existing reserved building, and construction and use safety is guaranteed.

The jacking underpinning structure 310 can stably support the jacking underpinning building body in the jacking process, the construction safety is guaranteed, the jacking underpinning structure can be used as a top plate of the underground structure 600 after the construction is finished and the jacking underpinning structure falls back to a required position, the phenomenon that the newly added underground structure collapses due to the fact that the existing reserved building generates overlarge pressure on the newly added underground structure 600 is avoided, and the construction and use safety is guaranteed.

In some embodiments, the underground structure 600 is formed using a cover and dig co-operation or a reverse operation. The cover-excavation-smoothing method is to construct the underground structure 600 from the lowest surface of the foundation pit to the foundation surface after the foundation pit body 110 is excavated to the foundation. The reverse method is to excavate the foundation pit body 110 and construct the underground structure 600 at the same time, i.e., one layer is excavated until the construction of the lowest layer of the underground structure 600 is completed.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.