Inclined strut deformation control structure for implementing foundation pit engineering through reverse construction method

Abstract

The utility model belongs to the field of underground space development, and relates to an inclined strut deformation control structure for implementing foundation pit engineering through a reverse construction method. According to the technical scheme, a middle supporting pile column and a top-down structure beam plate are arranged in a foundation pit support structure; the top-down structure beam plate is fixed on the foundation pit support structure and the middle support pile column; a lower inclined strut, an enclosing purlin and a stress transfer beam are arranged below the side span of the reverse structure beam plate; and the temporary bearing side columns support the stress transfer beams. The enclosing purlins are arranged on the side faces of the foundation pit enclosure structure, and the supporting plate structures and the servo jacks are arranged between the enclosing purlins and the stress transfer beams. The servo jack is placed on the supporting plate structure, one end of the lower inclined strut is connected with the stress conversion beam, and the other end of the lower inclined strut is connected with the middle supporting pile of the side span. The lower inclined strut can be quickly applied, overexcavation is not needed in the construction process, the support-free exposure time of the enclosure structure is shortened, and deformation of the enclosure structure is further reduced. On the basis, a servo jack is additionally arranged in combination with the lower inclined strut, jacking force is applied to the enclosure structure, and deformation of the foundation pit can be further reduced.

Description

Technical Field

[0001] The utility model belongs to the field of underground space development, and particularly relates to a deformation control structure in the case of complex surrounding environment of a foundation pit in the central urban area and high requirements for deformation control of the foundation pit retaining structure. Background Technique

[0002] With the rapid development of urban underground space, new problems and challenges have constantly emerged in the design and construction of foundation pit projects. The urban underground space has changed from the traditional single functions such as commerce and parking to an underground complex with multiple functions, and the scale of foundation pit projects has continuously increased. In addition, foundation pit projects in the central urban area are often adjacent to protection objects such as subways, protected buildings, and underground pipe networks. The surrounding environmental conditions of the foundation pit are becoming increasingly complex and sensitive, and the requirements for deformation control during the implementation of the foundation pit are also getting higher and higher.

[0003] The top-down method is a commonly used support method in the field of foundation pit engineering. In this method, intermediate support piles are cast or driven at relevant positions inside the building to serve as the support structure for bearing the self-weight of the upper structure and construction loads before the bottom slab is sealed during the construction period. The structural beam slabs of each basement layer are excavated downward for construction as the horizontal support of the retaining structure. The top-down method has the following prominent advantages compared with the conventional bottom-up method for foundation pits: (1) Since the structural beam slab of the first floor on the ground is completed first, the upper structure construction can be carried out synchronously during the downward top-down excavation process, thus significantly shortening the construction period; (2) It avoids the waste phenomenon of using temporary supports, and the engineering economic benefits are remarkable, which is conducive to realizing the green and sustainable development of foundation pit projects; (3) The horizontal top-down structural beam slab support has large stiffness and high safety.

[0004] Although the top-down method has the above advantages, in the case of very high requirements for surrounding environment protection, there are still certain deficiencies in the top-down method for controlling the deformation of the foundation pit: (1) The construction speed of the underground top-down structural beam slabs is usually slow. In soft soil areas represented by Shanghai, soft clay has rheological properties. Before the construction of the top-down beam slabs is completed and an effective horizontal support is formed, the deformation of the foundation pit will continuously accumulate and increase with time; (2) In order to ensure the construction quality and dimensional accuracy of the top-down structural beam slabs during the top-down method construction, it is usually necessary to adopt the method of erecting a falsework for construction. Therefore, a certain depth needs to be overexcavated at each stage of the foundation pit excavation process, which is also not conducive to the deformation control of the foundation pit.

[0005] At present, the research on foundation pit projects implemented by the top-down method, especially the technical means for controlling the deformation of the foundation pit retaining structure and reducing the influence of the foundation pit on the surrounding environment, is still not mature. Content of the Utility Model

[0006] The utility model provides a diagonal brace deformation control structure for implementing foundation pit engineering by the top-down method, which is especially applicable to the development of large-depth multi-layer underground space under complex and sensitive environmental conditions in the central urban area. This structure is applied in the top-down deep foundation pit engineering to effectively reduce the impact of the construction process on the surrounding buildings and underground pipe networks of the foundation pit.

[0007] The technical solution of the utility model is as follows:

[0008] A diagonal brace deformation control structure for implementing foundation pit engineering by the top-down method. Inside the foundation pit retaining structure are intermediate support piles and columns and top-down structural beam slabs; the top-down structural beam slabs are fixed on the foundation pit retaining structure and intermediate support piles; under the side spans of the top-down structural beam slabs, lower diagonal braces, collar beams and force transfer beams are arranged; temporary support side columns support the force transfer beams. The collar beam is arranged on the side of the foundation pit retaining structure, and a support plate structure and a servo jack are arranged between the collar beam and the force transfer beam; the servo jack is placed on the support plate structure, one end of the lower diagonal brace is connected to the force transfer beam, and the other end is connected to the intermediate support pile of the side span.

[0009] Based on the above technical features: one end of the support plate structure is connected to the collar beam, and the other end is disconnected from the force transfer beam.

[0010] Based on the above technical features: the connection point of the lower diagonal brace and the intermediate support pile is located at the beam-column joint of the top-down structural beam slab. Connecting at the beam-column joint, the horizontal force can be transmitted to the main structural beam of the top-down structural beam slab to ensure the safety of the column.

[0011] Based on the above technical features: the collar beam and the foundation pit retaining structure are connected by suspension bars.

[0012] The concept and beneficial effects of the above technical solution are as follows: The top-down structural beam slabs usually need to be constructed by erecting formwork scaffolds. Therefore, a certain depth needs to be overexcavated at each stage of the foundation pit excavation process, which is not conducive to the control of foundation pit deformation. In addition, if the basement floor height is large and the single-layer earthwork excavation depth is large, it is also easy to cause large deformation of the retaining structure. Adding lower diagonal braces to each layer of the top-down structural beam slabs is equivalent to increasing the number of temporary supports acting on the retaining structure, and at the same time giving full play to the characteristics of the large stiffness and high bearing capacity of the top-down structural beam slabs. Compared with the whole-layer top-down structural beam slabs, the lower diagonal braces only arranged around the foundation pit can be quickly applied, and there is no need for overexcavation during the construction process, shortening the unsupported exposure time of the retaining structure, and thus reducing the deformation of the retaining structure. On this basis, combining the addition of servo jacks with the lower diagonal braces to apply a jacking force on the retaining structure can further reduce the deformation of the foundation pit. The reaction force formed by the jack is transmitted to the top-down structural beam slabs through the lower diagonal braces, and the vertical discrete force generated during the force transmission process can be borne by the temporary support side columns. Description of the Drawings

[0013] Figure 1It is a schematic cross-sectional view of the inclined strut and the servo system arranged in combination with the inverted construction structural beam-slab in this technical solution.

[0014] The reference numerals in the figure are indicated as follows: foundation pit retaining structure 1; temporary support side column 2; intermediate support pile column 3; inverted construction structural beam-slab 4; inclined strut 5; purlin 6; force conversion beam 7; support plate structure 8; servo jack 9; suspension bar 10. Specific embodiments

[0015] The following further details the specific embodiments of the present utility model in conjunction with the accompanying drawings. These embodiments are only used to illustrate the present utility model and are not intended to limit the present utility model.

[0016] In the description of the present utility model, it should be noted that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0017] In addition, in the description of the present utility model, unless otherwise specified, the meaning of "a plurality" is two or more.

[0018] As Figure 1 shown, the foundation pit is excavated to a certain depth below the inverted construction structural beam-slab 4, and the complete inverted construction structural beam-slab 4 is constructed. The inverted construction structural beam-slab 4 is fixedly connected to the intermediate support pile column 3 and the foundation pit retaining structure 1.

[0019] An inclined strut 5, a purlin 6 and a force conversion beam 7 are arranged below the side span of the inverted construction structural beam-slab 4; the temporary support side column 2 supports the force conversion beam 7; the purlin 6 is connected to the foundation pit retaining structure 1 through a suspension bar 10. A support plate structure 8 and a servo jack 9 are arranged between the purlin 6 and the force conversion beam 7; the servo jack 9 is placed on the support plate structure 8.

[0020] One end of the inclined strut 5 is connected to the force conversion beam 7, and the other end is connected to the intermediate support pile column 3. The connection point of the inclined strut 5 and the intermediate support pile column 3 is preferably at the beam-column joint of the inverted construction structural beam-slab 4. Connecting at the beam-column joint, the horizontal force can be transmitted to the main structural beam of the inverted construction structural beam-slab to ensure the safety of the column.

[0021] In the above technical solution, one end of the supporting plate structure 8 is connected to the waling beam 6, and the other end should be disconnected from the force transfer beam 7, which can prevent the supporting plate structure 8 from being damaged when the servo jack 9 applies the jacking force. Additionally, if both ends of the supporting plate structure 8 are respectively connected to the waling beam 6 and the force transfer beam 7 at the same time, it will restrict the jacking of the servo jack 9.

[0022] In foundation pit engineering, due to the unloading of the soil excavation in the foundation pit, the retaining structure deforms towards the inside of the foundation pit, which in turn causes settlement deformation of the buildings and underground pipelines outside the pit. In this technical solution, in addition to the inverse construction structural slab 4 providing the thrust for the foundation pit retaining structure 1, the servo jack 6 applies the jacking force to further provide the thrust for the foundation pit retaining structure 1, thereby reducing the deformation of the foundation pit retaining structure 1. Additionally, the inclined strut 5 further provides the stiffness of the inverse construction structural slab 4. Combined with the servo jack 6, the force transmission path is made more efficient. Under this technical solution, the structure of the inverse construction structural slab 4 can be not damaged. At the same time, the inclined strut can be quickly applied, and there is no need for overexcavation during the construction process, shortening the unsupported exposure time of the retaining structure, and thus reducing the deformation of the retaining structure. On this basis, by adding servo jacks in combination with the inclined struts and applying the jacking force on the retaining structure, the foundation pit deformation can be further reduced.

[0023] The above are only the preferred embodiments of the present utility model. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present utility model, several improvements and substitutions can still be made, and these improvements and substitutions should also be regarded as the protection scope of the present utility model.

Claims

1. An inclined strut deformation control structure for implementing foundation pit engineering by the top-down method. Inside the foundation pit retaining structure (1) are intermediate support pile columns (3) and top-down structural beam slabs (4); the top-down structural beam slabs (4) are fixed on the foundation pit retaining structure (1) and the intermediate support pile columns (3); it is characterized in that: An inclined strut (5), a waling (6) and a force transfer beam (7) are arranged below the side span of the beam-slab (4) of the top-down structure; a temporary supporting side column (2) supports the force transfer beam (7); the waling (6) is arranged on the side surface of the foundation pit retaining structure (1), and a supporting plate structure (8) and a servo jack (9) are arranged between the waling (6) and the force transfer beam (7); the servo jack (9) is placed on the supporting plate structure (8), one end of the inclined strut (5) is connected to the force transfer beam (7), and the other end is connected to the intermediate supporting pile column (3) of the side span.

2. The inclined strut deformation control structure for the excavation engineering implemented by the top-down method according to claim 1, characterized in that: One end of the supporting plate structure (8) is connected to the waling (6), and the other end is disconnected from the force transfer beam (7).

3. The inclined strut deformation control structure for implementing foundation pit engineering by the top-down method according to claim 1, characterized in that: The connection point of the inclined strut (5) and the intermediate supporting pile column (3) is located at the beam-column joint of the beam-slab (4) of the top-down structure.

4. The inclined strut deformation control structure for implementing foundation pit engineering by the top-down method according to claim 1, characterized in that: The waling (6) and the foundation pit retaining structure (1) are connected by hanger bars (10).

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