阅读说明：本技术 一种超大桩间距深基坑支护体系的施工方法 (Construction method of ultra-large pile spacing deep foundation pit supporting system ) 是由 吕佼佼 高徐军 张友科 刘园 苏国省 柳兴旺 白鹤 甘鹏山 秦青阳 韩文斌 贾彦 于 2020-01-14 设计创作，主要内容包括：本发明提供了一种超大桩间距深基坑支护体系的施工方法,沿基坑的长度方向等间距施工两排支护桩,当支护桩的施工处有既有构筑物时,跨越既有构筑物后施工支护桩,支护桩施工完后,在支护桩顶部施工冠梁,然后在既有构筑物两侧的支护桩之间施工板墙,板墙采用逆法施工,板墙施工完成后,施工支撑系统。支护桩等间距施工的间距不大于支护桩桩径的2倍,既有构筑物两侧的支护桩间距大于支护桩桩径的2倍。与现有技术相比,通过将排桩支护和逆作法施工结合起来,充分利用二者的优点,结构简单、安全可靠、施工方便、造价低。同时避免使用锚索,对基坑保护的同时也实现了对既有建筑及管线的保护,在城市市政等领域的基坑支护中有较好的应用前景。(The invention provides a construction method of a deep foundation pit supporting system with an ultra-large pile spacing, which comprises the steps of constructing two rows of supporting piles at equal intervals along the length direction of a foundation pit, constructing the supporting piles after spanning the existing structures when the construction positions of the supporting piles have the existing structures, constructing crown beams at the tops of the supporting piles after the supporting piles are constructed, constructing plate walls between the supporting piles at two sides of the existing structures, constructing the plate walls by a reverse method, and constructing a supporting system after the plate wall construction is finished. The spacing of the supporting piles in the equidistant construction is not more than 2 times of the pile diameter of the supporting piles, and the spacing of the supporting piles on two sides of the existing structure is more than 2 times of the pile diameter of the supporting piles. Compared with the prior art, the row pile support and the reverse construction method are combined, the advantages of the row pile support and the reverse construction method are fully utilized, and the device is simple in structure, safe, reliable, convenient to construct and low in manufacturing cost. Meanwhile, anchor cables are avoided, the existing buildings and pipelines are protected while the foundation pit is protected, and the method has a good application prospect in foundation pit support in the fields of urban municipal administration and the like.)

1. A construction method of a super-large pile spacing deep foundation pit supporting system is characterized by comprising the following steps: the method comprises the steps of constructing two rows of supporting piles (1) at equal intervals along the length direction of a foundation pit, constructing the supporting piles (1) after crossing the existing structures (2) when the existing structures (2) exist at the construction positions of the supporting piles (1), constructing crown beams (5) at the tops of the supporting piles (1) after the supporting piles (1) are constructed, and constructing plate walls (4) between the supporting piles (1) on two sides of the existing structures (2), wherein the plate walls (4) are constructed in a reverse method, and constructing a supporting system after the plate walls (4) are constructed.

2. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 1, characterized by comprising the following steps: the spacing of the supporting piles (1) in the equidistant construction is not more than 2 times of the pile diameter of the supporting piles (1), and the spacing of the supporting piles (1) on two sides of the existing structure (2) is more than 2 times of the pile diameter of the supporting piles (1).

3. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 1, characterized by comprising the following steps:

step 1), constructing a support pile (1), and when encountering an existing structure (2), spanning the existing structure (2) to construct the support pile (1);

step 2), constructing a crown beam (5) after the construction of the support pile (1) is finished;

step 3), carrying out earth excavation on the arrangement position of the plate wall (4) in a layering manner, exposing the support piles (1), putting a first layer of plate wall (10) steel bar model, and respectively connecting the support piles (1) and the crown beams (5) with the first layer of plate wall (10) steel bars;

step 4), casting a first layer of plate wall (10) in situ, wherein the casting is performed between the two fender piles (1) from top to bottom, a wood formwork (12) is adopted for formwork support, and after the first layer of plate wall (10) reaches the design strength, the step 3) is repeated to perform the construction of the rest layer of plate wall;

and 5) after the construction of all the laminated walls is finished, constructing a supporting system to form a supporting system.

4. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 1, characterized by comprising the following steps: the supporting pile (1) is a cast-in-place pile (8), a tubular pile or a steel pipe pile.

5. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 1, characterized by comprising the following steps: the supporting system comprises a pressure plate (3) and a supporting beam (11), the crown beam (5) and the supporting beam (11) are connected through the pressure plate (3), the pressure plate (3) is vertically connected with the supporting pile (1) and the supporting beam (11), and the thickness of the supporting beam (11) is larger than that of the pressure plate (3) and the crown beam (5).

6. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 3, characterized by comprising the following steps: in the step 3), the height of the earth excavation is not more than 2 m.

7. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 3, characterized by comprising the following steps: in the step 3), the surface is cleaned after the supporting pile (1) is exposed, the protective layer of the supporting pile (1) in the height range of the first layer of plate wall (10) is stripped, so that the vertical steel bars of the supporting pile (1) are exposed, the transverse steel bars (7) of the plate wall are connected with the vertical steel bars of the supporting pile (1) at intervals of 150-250mm along the pile height direction, meanwhile, the upper ends of the longitudinal steel bars (6) of the plate wall are connected with the planting steel bars of the crown beam (5) at intervals of 150-250mm along the length direction of the crown beam (5), and the lower ends of the longitudinal steel bars (6) of the plate wall are inserted into the un-excavated soil body to serve as connecting steel bars.

8. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 1, wherein the pile diameter of the supporting pile (1) is 800-1200mm, the size of the crown beam (5) is 800 × 800-1200 × 800mm, and the thickness of the plate wall 4 is 400-600 mm.

9. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 5, characterized by comprising the following steps: when the supporting system is constructed, the pressure head plate (3) is connected with the crown beam (5), the supporting beam (11) is arranged at the other end of the pressure head plate (3), and the pressure head plate (3) and the supporting beam (11) are both embedded into the ground at the top of the foundation pit.

10. The construction method of the ultra-large pile spacing deep foundation pit supporting system according to claim 7, characterized by comprising the following steps: the longitudinal steel bar (6) of the plate wall is[email protected] 150. the transverse steel bars (7) of the plate wall are[email protected]。

Technical Field

The invention belongs to the technical field of municipal infrastructure, and particularly relates to a construction method of a super-large pile spacing deep foundation pit supporting system.

Background

With the rapid development of economy in China, ground buildings are larger and larger in scale, underground spaces are developed deeply, the requirements on foundation pit engineering are also continuously improved, and the problems of safety and stability of deep foundation pit supporting are complicated. The deep foundation pit engineering belongs to temporary engineering, and its technical complexity is far higher than that of permanent foundation construction

In the excavation process of the deep foundation pit, in order to ensure the safety and reliability of the deep foundation pit and prevent casualties and property loss caused by collapse of the deep foundation pit, excavated peripheral soil bodies are often required to be supported so as to ensure the safety of the deep foundation pit, peripheral buildings (structures), underground pipe networks, roads and the like. The conventional construction method is that the periphery of the deep foundation pit is firstly supported by reinforced concrete row piles, cement-soil row piles, steel sheet piles, soil nail retaining walls and the like, or one or more of the reinforced concrete row piles, the cement-soil row piles, the steel sheet piles, the soil nail retaining walls and the like are combined to form a combined body to form a retaining support.

At present, the open cut method is a main construction method for domestic urban underground engineering construction, the row pile support is one of common foundation pit support forms, and compared with an underground continuous wall support, the row pile support has the advantages of simple construction process, low cost, flexible arrangement and the like. However, the distance between the piles needs to be determined according to the stress of the piles and the stable condition of soil between the piles, which is generally not more than 2 times of the diameter of the cast-in-place pile, and the distance between the cast-in-place piles needs to be increased if the construction with larger underground width, such as pipelines, is met in the engineering.

In addition, if the soil quality of the working area is complex, the difficulty of increasing the distance between the filling piles 8 is further increased if the soil layer is included. In the face of such complex engineering geological conditions, the existing row pile foundation pit supporting mode is difficult to develop. In particular, in a soft soil area, in order to solve the above problem, a support system of a pile support or a pile anchor is generally used. The pile support system has high cost and long construction period, the pile anchor system is easy to disturb the foundation soil in the construction process, and when the soft soil layer is thick, in order to meet the designed uplift bearing capacity, the anchor section needs to penetrate through the soft soil layer, so that great environmental risk is caused in the aspect of foundation pit support and great waste is caused.

Disclosure of Invention

The invention aims to provide a construction method of a deep foundation pit supporting system with an ultra-large pile spacing, which overcomes the technical problems in the prior art.

Therefore, the technical scheme provided by the invention is as follows:

a construction method of a super-large pile spacing deep foundation pit supporting system includes constructing two rows of supporting piles at equal intervals along the length direction of a foundation pit, constructing the supporting piles after spanning existing structures when the existing structures exist at the construction positions of the supporting piles, constructing crown beams at the tops of the supporting piles after the supporting piles are constructed, and constructing a plate wall between the supporting piles on two sides of the existing structures, wherein the plate wall is constructed in a reverse method, and constructing a supporting system after the plate wall is constructed.

The spacing of the supporting piles in the equidistant construction is not more than 2 times of the pile diameter of the supporting piles, and the spacing of the supporting piles on two sides of the existing structure is more than 2 times of the pile diameter of the supporting piles.

A construction method of a deep foundation pit supporting system with an ultra-large pile spacing specifically comprises the following steps:

step 1), supporting pile construction, namely, when an existing structure is met, spanning the existing structure to carry out supporting pile construction;

step 2), constructing a crown beam after the construction of the support pile is finished;

step 3) carrying out earth excavation layer by layer at the arrangement position of the plate wall, exposing the support piles, inserting a first layer of plate wall steel bar model, and respectively connecting the support piles and the crown beams with the first layer of plate wall steel bars;

step 4), casting a first layer of plate wall in situ, wherein the casting is performed from top to bottom between the two retaining piles, a wood formwork 12 is adopted for formwork support, and after the first layer of plate wall reaches the design strength, the step 3) is repeated to perform the construction of the rest layer of plate wall;

and 5) after the construction of all the laminated walls is finished, constructing a supporting system to form a supporting system.

The supporting pile is a cast-in-place pile, a tubular pile or a steel pipe pile.

The supporting system comprises a top pressing plate and a supporting beam, the top beam and the supporting beam are connected through the top pressing plate, the top pressing plate is vertically connected with the supporting piles and the supporting beam, and the thickness of the supporting beam is larger than that of the top pressing plate and that of the top beam.

In the step 3), the height of the earth excavation is not more than 2 m.

In the step 3), after the supporting pile is exposed, the surface is cleaned, the protecting layer of the supporting pile in the height range of the first layer of the plate wall is stripped, so that the vertical steel bars of the supporting pile are exposed, the transverse steel bars of the plate wall are connected with the vertical steel bars of the supporting pile at intervals of 150-250mm along the pile height direction, meanwhile, the upper ends of the longitudinal steel bars of the plate wall are connected with the embedded steel bars of the crown beam at intervals of 150-250mm along the length direction of the crown beam, and the lower ends of the longitudinal steel bars of the plate wall are inserted into the un-excavated soil body to serve as connecting steel bars.

The pile diameter of the support pile is 800-1200mm, the size of the crown beam is 800 × 800-1200 × 800mm, and the thickness of the plate wall is 400-600 mm.

When the supporting system is constructed, the pressure head plate is connected with the crown beam, the supporting beam is arranged at the other end of the pressure head plate, and the pressure head plate and the supporting beam are both embedded into the ground at the top of the foundation pit.

The longitudinal steel bar of the plate wall is[email protected], and the transverse steel bars of the plate wall are[email protected]。

The invention has the beneficial effects that:

compared with the prior art, the construction method of the ultra-large pile spacing deep foundation pit supporting system provided by the invention has the advantages that row pile supporting and reverse construction are combined, the advantages of the row pile supporting and the reverse construction are fully utilized, the structure is simple, the safety and the reliability are realized, the construction is convenient, and the manufacturing cost is low. Meanwhile, anchor cables are avoided, the existing buildings and pipelines are protected while the foundation pit is protected, and the method has a good application prospect in foundation pit support in the fields of urban municipal administration and the like.

The invention adopts the combination of the support piles and the plate wall, and transmits the lateral force to the support piles through the plate wall structure so as to realize the increase of the spacing between the support piles, is suitable for foundation pit engineering under the complex condition of the existing structure of the cross-region, realizes the pile arrangement supporting method with large pile spacing under the unfavorable engineering geological conditions such as the existence of a sand layer and the like, and obtains good social and economic benefits.

The invention overcomes the defects that the conventional method needs to move and change pipelines, so that more earthwork excavation is caused, the movement and change of the pipelines can influence the operation of the existing pipelines, and the side wall of the foundation pit is supported through the construction panel wall, so that the safety risk caused by soil collapse is avoided.

The invention constructs a complete supporting structure by constructing the supporting piles, the crown beams, the plate walls and the supporting system in sequence, thereby protecting the safety of the construction of the underground main body structure and the surrounding environment of the foundation pit. The supporting system is connected with the top beam through the top pressing plate and embedded into the ground at the top of the foundation pit, the horizontal rigidity of the foundation pit supporting system is increased, the supporting beam is arranged at the other end of the top pressing plate and is thicker than the top pressing plate and the top beam and embedded into the ground at the top of the foundation pit, a fulcrum of the whole pile top supporting structure is formed and used as an anchor of the top pressing plate and the top beam to form the supporting system, the overall rigidity and the horizontal rigidity of the foundation pit supporting system are increased, and the horizontal displacement of the pile top of the supporting structure is controlled.

In order to make the aforementioned and other objects of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

FIG. 1 is a schematic view of a connection between a panel wall and a fender pile;

FIG. 2 is a block construction schematic diagram of the panel wall of the present invention;

FIG. 3 is a schematic longitudinal section of a panel wall construction;

fig. 4 is a schematic structural view of the support system.

In the figure:

description of reference numerals:

1. supporting piles; 2. existing structures; 3. pressing a top plate; 4. a panel wall; 5. a crown beam; 6. longitudinal steel bars of the plate wall; 7. transverse steel bars of the plate wall; 8. filling piles; 9. excavating the surface in layers; 10. a first deck wall; 11. a support beam; 12. and (5) wood molding.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

The exemplary embodiments of the present invention will now be described with reference to the accompanying drawings, however, the present invention may be embodied in many different forms and is not limited to the embodiments described herein, which are provided for complete and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting of the invention. In the drawings, the same units/elements are denoted by the same reference numerals.

Unless otherwise defined, terms (including 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. Further, it will be understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense.