CN108286254A - Neighbouring important feature strip foundation pit remaining soils separate subregion excavation construction structure - Google Patents

Abstract

The invention relates to the technical field of construction engineering, and relates to a structure and a construction method for excavating and excavating the reserved soil body of a strip-shaped foundation pit adjacent to an important structure. Small pits are set independently on the important structure side, and soil is reserved for adjacent foundation pits in the vertical direction and sloped for support, providing horizontal reaction force for the excavation of independent sub-pit, and other areas are constructed simultaneously with independent small pits. The present invention innovates the sequential excavation construction method of the conventional long-strip deep and large foundation pits adjacent to important structures, and realizes simultaneous construction in other areas except the reserved soil range under the premise of ensuring the safety of important structures adjacent to the foundation pit, thereby It reduces the difficulty of construction deployment and effectively shortens the overall construction period.

Description

The construction structure of the excavation of the reserved soil in the long-strip foundation pit adjacent to the important structure

technical field

The invention relates to the technical field of building foundation pit engineering, in particular to a construction structure and a construction method for excavating and excavating the reserved soil body in a strip-shaped foundation pit adjacent to an important structure.

Background technique

In recent years, my country's real estate industry has developed vigorously, various types of buildings have sprung up, and urban construction land has become increasingly tense. In order to make full use of space and alleviate the shortage of urban land, modern cities have adopted strategies to develop high-altitude and underground. There are more and more high-rise and super high-rise buildings, and large-scale deep foundation pit technology is also being used more and more.

With the development and changes of urban layout and overall planning, there are more and more projects for the integrated development of large-scale underground space adjacent to important structures, forming complexes with multiple functions. In order to ensure the safety of adjacent important structures, the adjacent deep foundation pit engineering usually adopts the process arrangement of subdivided pits and sequential construction. This process arrangement has many problems such as slow construction speed, long overall construction period, high construction cost, and difficult construction deployment.

For example, the subways that are being built or are about to be built in major cities. A large number of deep foundation pit projects are involved in the construction of urban subways, and they are often located in densely built areas, so the mutual influence between deep foundation pit construction and surrounding buildings inevitably arises. Regarding the construction of such adjacent deep foundation pits, a large number of scholars have realized that the previous strength design theory of foundation pit engineering can no longer meet the safety requirements of the surrounding environment of the project, and the increasingly strict requirements for deformation control of foundation pit engineering are applied to actual projects. Among them, there are still many problems to be solved in the construction of adjacent deep foundation pits.

Contents of the invention

In order to overcome various problems such as slow construction speed, long overall construction period, high construction cost, and difficulty in construction deployment when deep and large foundation pits are divided into deep and large foundation pits adjacent to important structures, and conventional construction procedures are arranged sequentially in different areas, the present invention provides an adjacent important structure. The excavation construction structure of the reserved soil in the long strip foundation pit is divided into partitions, and the invention also provides a construction method of the structure.

The technical solution of the present invention is: a construction structure for excavating and excavating the reserved soil body of a strip-shaped foundation pit adjacent to an important structure, which mainly includes a strip-shaped foundation pit and an important structure;

The important structure mentioned already exists and is in normal operation, located on the short side of the long strip foundation pit to be excavated, and needs to be protected during the excavation process of the foundation pit;

The strip-shaped foundation pit is a foundation pit whose length ratio between the long side and the short side is greater than 3, and the short side is adjacent to important structures, and can be divided into three major areas: independent small sub-pit, reserved soil area and other partitions;

The independent small sub-pit is a long strip foundation pit adjacent to the side of the important structure, which is independently divided by the enclosure structure, and is required to ensure the first excavation and construction of small-scale foundation pits;

The reserved soil area is the slope top width 1 to 2 times the excavation depth of the foundation pit left in the adjacent foundation pit of the independent small sub-pit. Sub-pit excavation provides horizontal support and reaction force;

The other partitions are areas separated by reserved soil and away from important structures and independent small sub-pit, and this structure can also be used for construction according to the surrounding environment and the length-to-width ratio of the foundation pit;

A pit-in-a-pit is set in the other partitions, and the pit-in-a-pit is a deep pit located in the center of the other partitions with an area smaller than that of other partitions, and is mainly composed of retaining piles and a bottom plate;

The perimeter of the strip-shaped foundation pit is a foundation pit enclosure structure, and the foundation pit enclosure structure includes a foundation pit enclosure continuous wall and a foundation pit enclosure protection pile, and anchors are arranged in the foundation pit enclosure continuous wall. pole one.

Further, in the above scheme, the reserved soil grading support is a support method that can ensure the stability of the reserved soil slope by adopting a more economical support form such as soil nailing wall grading support.

The present invention also provides a method for excavating and excavating the reserved soil adjacent to the strip-shaped foundation pit adjacent to the important structure, and the steps are as follows:

Step 1: Level the site, complete the construction division of the long strip foundation pit, set up independent small sub-pits adjacent to important structures, reserve a certain width of soil for adjacent sub-divisions, and separate small sub-pits from independent small sub-pits by sub-pit piles, and the remaining areas for other partitions;

Step 2: Complete the foundation pit enclosure structure construction on the ground;

Step 3: Except for the reserved soil area, all other areas shall be excavated at the same time, and priority shall be given to ensuring the construction progress of independent small sub-pits adjacent to important structures;

Step 4: After the main structure of the independent small sub-pit area is ±0.00, excavate the reserved soil area, and at the same time implant anchor rod 2 from the reserved soil area to the adjacent important structure;

Step 5: Reserve the soil area for construction to the base, and when constructing the main structure from bottom to top, according to the results of numerical simulation and monitoring data analysis, the horizontal support between the structure and the sub-pit piles can be appropriately canceled;

Step 6: After the construction of the structure below ±0.00 on both sides of the sub-pit pile is completed, the sub-pit pile is removed from top to bottom;

Step 7: If the structure replacement in step 5 is cancelled, the sub-pit piles can be dismantled from top to bottom to the base at one time;

Step 8: If the sub-pit piles are removed to the base at one time from top to bottom, the post-casting belt can be closed sequentially from bottom to top, and the structures on both sides of the sub-pit piles are connected as a whole.

Furthermore, a 500mm long angle steel is pre-embedded in the post-casting belt, and the post-casting belt is pre-embedded with the angle steel, which can ensure the safety of the main structure.

The beneficial effects of the present invention are:

(1) Compared with the sequential excavation method of multiple sub-pits, the excavation method of reserved soil separated by partitions can not only effectively control the safety risks of adjacent important structures and the adjacent foundation pit itself, but also ensure that the adjacent important structures are divided into two parts. The pit was completed first;

(2) It solves the construction deployment problems caused by the sequential excavation of multiple sub-pits, such as labor and machinery layoffs or multiple entry and exit, and effectively saves construction costs;

(3) The reserved soil is divided into partitions for construction, so that all partitions except the reserved soil area can be constructed at the same time, which can effectively shorten the overall construction period of the project.

Description of drawings

Fig. 1 is the plane view of the divisional structural schematic diagram of the excavation construction area of the excavation construction area reserved by the reserved soil body of the strip-shaped foundation pit adjacent to the important structure of the patent of the present invention;

Fig. 2 is the front view of the divisional structural diagram of the excavation construction area division of the excavation construction area reserved for the excavation and construction area of the reserved soil body in the elongated foundation pit adjacent to the important structure of the patent of the present invention;

Fig. 3 is a schematic diagram of horizontal support replacement of the structure on both sides of the divided pit pile;

Fig. 4 is a schematic diagram of one-time dismantling of the split-pit pile from top to bottom;

Fig. 5 is a bottom-up closed construction schematic diagram of the post-casting zone structure of the divided pit pile;

Among them, 1—important structure; 2—independent small sub-pit; 3—reserved soil area; 4—other partitions; 5—divided pit pile; 6—replacement of structure; Guard pile; 9—post-pouring belt; 10—main structure, 11—diaphragm wall for foundation pit enclosure, 12—anchor 1, 13—anchor 2, 14—pit-in-pit.

Detailed ways

As shown in attached drawings 1 and 2, the excavation construction structure of the reserved soil of the long-strip foundation pit adjacent to the important structure is divided into partitions, mainly including the long-strip foundation pit and important structures; the important structure 1 already exists and has been in normal operation , is located on the short side of the long strip foundation pit to be excavated, and needs to be protected during the excavation process of the foundation pit; the long strip foundation pit is a foundation pit whose length ratio between the long side and the short side of the foundation pit is greater than 3, and the short side The direction is close to the important structure 1, which can be divided into three major areas: the independent small sub-pit 2, the reserved soil area 3 and other sub-divisions 4; Independently divided, it is required to ensure the first excavation of the small foundation pit; the reserved soil area 3 is the slope top width 1 to 2 times the excavation depth of the foundation pit left in the independent small sub-pit 2 adjacent to the foundation pit, which is reserved for simple The purpose of the soil platform for soil grading support is to provide horizontal support for the excavation of independent small sub-pit. The support method to ensure the stability of the reserved soil slope; the other partition 4 is an area separated by the reserved soil, away from the important structure 1 and the independent small sub-pit 2; the other partition 4 is set with a pit within a pit 15 and a pit within a pit 15 It is a deep pit located in the center of other division 4 and its area is smaller than that of other division 4. It is mainly composed of enclosure piles and floor plates; the surrounding of the long strip foundation pit is the foundation pit enclosure structure, and the foundation pit enclosure structure includes foundation pit enclosure Diaphragm wall 11 and foundation pit enclosing pile 8 are provided with anchor rod one 12 in the described foundation pit enclosing continuous wall.

Below, the present invention will be further described by taking the northern area of an underground space project in Suzhou as an example, in conjunction with the accompanying drawings.

The total area of the foundation pit in the north area of an underground space project in Suzhou is about 24,400 square meters. After the site is leveled, the elevation is 2.70m. The depth of the foundation pit is about 17.8m. The 84m short side of the foundation pit is adjacent to a subway station, about 32m away from the outer line of the station structure.

There are two independent foundation pits in the north area, the large foundation pit on the side away from the subway adopts an 800mm thick underground diaphragm wall + three inner concrete supports, and the small foundation pit on the side adjacent to the subway adopts an 800mm thick underground diaphragm wall + four inner supports (one concrete inner support support + three steel supports), between the two pits Divided by pit piles.

In order to protect the normal operation of subway lines and stations, it is required to first complete the area adjacent to the small pit of the subway, and then construct the area adjacent to the large pit. Through repeated studies, it is decided to adopt the construction method of the present invention.

The implementation steps are as follows:

Step 1: Level the site and complete the construction division of the strip-shaped foundation pit. The adjacent important structure (subway) 1 side is an independent sub-pit 2, and the adjacent large pit is adjacent to the side of the small pit. A certain width of reserved soil area 3 is reserved, which is separated from the independent sub-pit 2 by sub-pit piles 5, and the remaining area is other sub-divisions 4 ;

The second step: complete the foundation pit enclosure structure 8 construction on the ground;

Step 3: Except for the reserved soil body area 3, all other areas 2 and 4 are excavated at the same time, giving priority to ensuring the construction progress of the independent sub-pit 2 adjacent to the important (subway) structure side;

Step 4: After the main structure 10 in the area of the independent sub-pit 2 is ±0.00, excavate the reserved soil area 3, and at the same time implant the anchor rod 2 13 from the reserved soil area 3 to the adjacent important structure 1;

Step 5: The reserved soil area 3 is constructed to the base, and when the main structure 10 is constructed from bottom to top, according to the analysis results of numerical simulation and monitoring data, the horizontal structure replacement between the main structure 10 and the sub-pit pile 5 can be appropriately canceled. Support 6, as shown in Figure 3;

Step 6: After the main structure 10 on both sides of the sub-pit pile 5 is completed below ±0.00, the sub-pit pile 5 is removed from top to bottom;

Step 7: If the structure replacement 6 in the fifth step is cancelled, the sub-pit pile 5 can be dismantled to the base from top to bottom at one time, as shown in Figure 4;

Step 8: If the sub-pit pile 5 is removed to the base from top to bottom at one time, the post-casting belt 9 can be closed sequentially from bottom to top, and the main structures 10 on both sides of the sub-pit pile are connected as a whole, as shown in Figure 5.

Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the above-mentioned specific embodiments. The above-mentioned specific embodiments are only illustrative and not restrictive. Those of ordinary skill in the art Under the enlightenment of the present invention, people can also make many forms without departing from the purpose of the present invention and the scope of protection of the claims, and these all belong to the protection scope of the present invention.

Claims (3)

1. A construction structure for excavating and excavating reserved soil in strip-shaped foundation pits adjacent to important structures, characterized in that it mainly includes strip-shaped foundation pits and important structures; The important structure mentioned already exists and is in normal operation, located on the short side of the long strip foundation pit to be excavated, and needs to be protected during the excavation process of the foundation pit; The strip-shaped foundation pit is a foundation pit whose length ratio between the long side and the short side is greater than 3, and the short side is adjacent to important structures, and can be divided into three major areas: independent small sub-pit, reserved soil area and other partitions; The independent small sub-pit is a long strip foundation pit adjacent to the side of the important structure, which is independently divided by the enclosure structure, and is required to ensure the first excavation and construction of small-scale foundation pits; The reserved soil area is a slope top width 1 to 2 times the excavation depth of the foundation pit left in the independent small sub-pit adjacent to the foundation pit, and is a simple soil platform for grading and supporting the reserved soil; The other divisions are areas separated by reserved soil and far away from important structures and independent small subdivisions; A pit-in-a-pit is set in the other partitions, and the pit-in-a-pit is a deep pit located in the center of the other partitions with an area smaller than that of other partitions, and is mainly composed of retaining piles and a bottom plate; The perimeter of the strip-shaped foundation pit is a foundation pit enclosure structure, and the foundation pit enclosure structure includes a foundation pit enclosure continuous wall and foundation pit enclosure protection piles. 2. According to claim 1, the excavation construction structure for the reserved soil body of a strip-shaped foundation pit adjacent to an important structure is characterized in that, the grading support of the reserved soil body is such as a soil nail wall More economical support forms such as grading support can ensure the stability of the reserved soil slope. 3. according to claim 1 or 2, a kind of construction method of excavating the construction structure of the reserved soil in the strip-shaped foundation pit adjacent to the important structure, is characterized in that, the implementation steps are as follows: Step 1: Level the site, complete the construction division of the long strip foundation pit, set up independent small sub-pits adjacent to important structures, reserve a certain width of soil for adjacent sub-divisions, and separate small sub-pits from independent small sub-pits by sub-pit piles, and the remaining areas for other partitions; Step 2: Complete the foundation pit enclosure structure construction on the ground; Step 3: Except for the reserved soil area, all other areas shall be excavated at the same time, and priority shall be given to ensuring the construction progress of independent small sub-pits adjacent to important structures; Step 4: After the main structure of the independent small sub-pit area is ±0.00, excavate the reserved soil area, and at the same time implant anchor rod 2 from the reserved soil area to the adjacent important structure; Step 5: Reserve the soil area for construction to the base, and when constructing the main structure from bottom to top, according to the results of numerical simulation and monitoring data analysis, the horizontal support between the structure and the sub-pit piles can be appropriately canceled; Step 6: After the construction of the structure below ±0.00 on both sides of the sub-pit pile is completed, the sub-pit pile is removed from top to bottom; Step 7: If the structure replacement in step 5 is cancelled, the sub-pit piles can be dismantled from top to bottom to the base at one time; Step 8: If the sub-pit piles are removed to the base at one time from top to bottom, the post-casting belt can be closed sequentially from bottom to top, and the structures on both sides of the sub-pit piles are connected as a whole.