Pile-anchor deep foundation corner supporting structure and construction method
By setting up support piles, capping beams, and stabilizing components in the external corner area of the deep foundation pit to form an integral structure, the problems of anchor cable intersection and support pile tilting are solved, and the stability and construction convenience of the external corner area of the foundation pit are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUANGZHOU TIANZUO ARCHITECTURAL PLANNING & DESIGN CO LTD
- Filing Date
- 2023-08-21
- Publication Date
- 2026-06-02
AI Technical Summary
In deep foundation pit engineering, anchor cables in the external corner area of the foundation pit are prone to collision and crossover, causing inconvenience to construction. At the same time, the support piles in the external corner area are prone to tilting and instability, affecting the construction progress and safety.
A pile-anchor deep foundation pit corner support structure is adopted. Several support piles are set in the corner area of the foundation pit, and the support piles are connected by capping beams, stabilizing mechanisms, linear stabilizing components and triangular stabilizing components to form an integral structure, which increases the stability of the soil. When necessary, waist beams and anchor cables are set to enhance the support effect.
It effectively solved the problems of anchor cable intersection and support pile tilt, improved the soil stability and construction convenience in the external corner area of the foundation pit, and reduced construction difficulty and risk.
Smart Images
Figure CN117071581B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of deep foundation pit engineering technology, specifically relating to a pile-anchor deep foundation pit corner support structure and construction method. Background Technology
[0002] In deep foundation pit engineering, the support methods are generally divided into two main types: "with internal support" and "without internal support." With internal support, scaffolding piles and internal bracing are typically used, while without internal support, scaffolding piles and anchor cables are usually used. When using scaffolding piles and internal bracing, the internal bracing significantly impacts the excavation of the foundation pit, subsequent main structure construction, and the removal of internal bracing, leading to extended construction time and higher costs. Conversely, with scaffolding piles and anchor cables, the anchor cables are installed outwards from the foundation pit, eliminating obstruction from other support structures on the inner side. This facilitates excavation, provides ample internal space after reaching the foundation, and eliminates the need for additional construction steps such as removing internal bracing. Construction is flexible and convenient, saves time, and has relatively lower costs. Therefore, scaffolding piles and anchor cables are the preferred support method for deep foundation pit engineering.
[0003] However, difficulties have arisen in the construction of the external corner area of the deep foundation pit:
[0004] 1. If the anchor cables along the two right-angled sides in the area of the external corner of the foundation pit are installed outwards in the usual way, they will all be driven into the soil in the limited area of the external corner. Since the anchor cable spacing is fixed and the arrangement is dense, the anchor cables at the two right-angled sides will collide and cross in many areas, causing inconvenience in construction.
[0005] 2. In the external corner area, since both sides of the foundation pit are exposed, the soil is cut off by the support structure in two directions. Compared with soil exposed in only one direction, it is more unstable. Under the action of soil pressure in both directions, both sides of the foundation pit in the external corner area tend to tilt inward into the foundation pit, and the two sides cannot support each other (unlike the internal corner area of a deep foundation pit). Therefore, the tilting (deformation) of the support piles in the external corner area of a deep foundation pit is greater than in other areas, making it the most prone to failure.
[0006] In view of this, the present invention is hereby proposed. Summary of the Invention
[0007] To address the aforementioned problems in the existing technology, this invention provides a pile-anchored deep foundation pit corner support structure and construction method, which solves the problems of anchor cables colliding and crossing at the two right-angled sides of the foundation pit corner in many areas, causing inconvenience during construction and the unstable tilting of the support piles in the corner area of the foundation pit into the foundation pit.
[0008] The objective of this invention can be achieved through the following technical solution: a pile-anchored deep foundation pit corner support structure, comprising a plurality of support piles, the plurality of support piles being divided into two groups and respectively set on the two right-angled sides of the corner area of the foundation pit, each pair of adjacent support piles being connected by a fixing mechanism, and a stabilizing mechanism for preventing the support piles from tilting is provided in the corner area of the foundation pit.
[0009] As a further embodiment of the present invention, the fixing mechanism includes two crown beams, and each pair of adjacent support piles are connected by two crown beams, with the two crown beams perpendicular to any one of the support piles.
[0010] As a further embodiment of the present invention, the two sets of support piles are arranged at equal intervals on the two right-angled sides.
[0011] As a further embodiment of the present invention, the stabilizing mechanism includes a triangular stabilizing component, which is composed of a plurality of newly added piles arranged in a right-angled triangle array. The distance between any two adjacent newly added piles is twice the distance between the support piles. The distance between the newly added pile located at the right-angle vertex of the triangular stabilizing component and the two right-angled sides of the pit's external corner area is equal, both being twice the distance between the support piles.
[0012] As a further embodiment of the present invention, the stabilizing mechanism further includes a linear stabilizing component, which is composed of a number of newly added piles arranged in a linear array. The number of newly added piles are divided into two groups and respectively set on the extension lines of the two right-angled sides of the right-angled triangle array. The distance between any two adjacent newly added piles is twice the spacing between the support piles. The distance from the newly added pile at the intersection of the two groups of newly added piles and the extension lines of the right-angled sides of the right-angled triangle array to the nearest right-angled side of the pit's external corner area is twice the spacing between the support piles.
[0013] As a further embodiment of the present invention, each newly added pile in the triangular stabilizing component and the linear stabilizing component is connected by a tie beam.
[0014] A construction method for a pile-anchored deep foundation pit corner support structure includes the following steps:
[0015] Step S1: Before excavating the external corner of the foundation pit, first determine the external corner area of the foundation pit, and then set the first pile hole at equal intervals along the two right-angled sides of the external corner area of the foundation pit by measurement, and pour the support pile in the first pile hole.
[0016] Step S2: Excavate a trench in the soil between every two adjacent support piles, and pour concrete to form two cap beams. The two cap beams are fixedly connected to any one of the support piles, and the cap beams are used to form a whole with several support piles.
[0017] Step S3: Set up the second pile hole in a right triangle array within the area enclosed by 2 / 3 of the length of the two right-angled sides in the area of the external corner of the foundation pit, and pour the new pile in the second pile hole. Set up the third pile hole in a straight line array on the extension line of the two right-angled sides of the right triangle array, and pour the new pile in the third pile hole.
[0018] Step S4: Set up trenches in the soil between every two adjacent newly added piles in the right-angled triangle array and in the soil between every two adjacent newly added piles in the straight line array. This forms rows of parallel trenches parallel to the two right-angled sides and the hypotenuse in the right-angled triangle array, and parallel trenches parallel to the straight line array in the straight line array. Cast tie beams in all the parallel trenches to fix the newly added piles in the right-angled triangle array, the newly added piles in the straight line array, and the support piles into a solid whole.
[0019] As a further aspect of the present invention, the following steps are also included:
[0020] Step S5: After completing S1-S4, excavation can begin along the support piles at the external corner of the foundation pit until the excavation is complete, thus completing the construction.
[0021] Step S6: In step S1, the first pile hole is set at equal intervals along the two right-angled sides of the pit's external corner area by measurement. Here, the first pile hole set along one right-angled side is larger than the first pile hole set along the other right-angled side. Then, steps S2, S3, and S4 are performed. After step S4, a waist beam is set at the center of a group of support piles with smaller diameter. An anchor cable is installed on the waist beam, and finally step S5 is completed.
[0022] Step S7: In step S1, the diameter of the first pile hole, which is set at equal intervals along the two right-angled sides of the pit's external corner area, is larger than the diameter of the first pile hole in step S5. Then, proceed with steps S2, S3, and S4. Starting from the right-angled vertex of the pit's external corner area and ending at 2 / 3 of the distance of one set of support piles, a wainscoting is set at the center of the support piles between the starting and ending points. A wainscoting is also set below the center of the support piles outside this interval. In the same way, a wainscoting is set above and below the center of another set of support piles, and a wainscoting is also set at the center of the support piles outside this interval. Anchor cables are also set on all the wainscotings. Finally, step S5 is completed.
[0023] The beneficial effects of this invention are as follows:
[0024] This invention addresses the problem of poor soil stability and susceptibility to failure in the corner area of deep foundation pits by driving new piles into the soil in a specific pattern within the soil of the external corner region. Specifically, the new piles are arranged in a triangular pattern with the external corner within 2 / 3 of the total length of the supporting piles, and in a rectangular pattern with the supporting piles on both sides outside the 2 / 3 length. The new piles are aligned with the existing supporting piles and are spaced one at a time. This solves the problem of poor soil stability and susceptibility to failure in the corner area of deep foundation pits, achieving the strengthening effect of the new piles on the soil in the corner area, such as "nailing" and compaction. Furthermore, tie beams are installed on the new piles in the corner area of the foundation pit. This invention not only sets up transverse and longitudinal tie beams between the newly added piles and the support piles, but also solves the problems of weak support in the external corner area of the foundation pit and the mutual interference of transverse and longitudinal anchor cables in the external corner by using different anchor cable fixing positions for three cases: general foundation pit depth, relatively deep foundation pit depth, and very deep foundation pit depth. Furthermore, by making corresponding technical solutions for different foundation pit depths, it can be ensured that, in any case, the support piles in the external corner area of the deep foundation pit will not tilt into the foundation pit, and the anchor cables will not cross. This invention has a simple structure, strong practicality, and can be widely used in deep foundation pit engineering. Attached Figure Description
[0025] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.
[0026] Figure 1 This is a schematic diagram of the overall structure of the present invention;
[0027] Figure 2 This is a schematic diagram showing the positions of the inner and outer sides of the foundation pit according to the present invention;
[0028] Figure 3 This is a schematic diagram of the installation of the newly added piles according to the present invention;
[0029] Figure 4 This is a schematic diagram of the installation of the support piles according to the present invention;
[0030] Figure 5 This is a schematic diagram of an anchor cable structure of the present invention;
[0031] Figure 6 This is a schematic diagram of the installation of the two anchor cables according to the present invention;
[0032] Figure 7 This is a schematic diagram of the installation of the waist beam of the present invention;
[0033] Explanation of key component symbols:
[0034] In the diagram: 1. Support pile; 2. Crown beam; 3. Newly added pile; 4. Tie beam; 5. Anchor cable; 6. Waist beam; 7. Bottom of the foundation pit; 8. Ground outside the foundation pit; A. Inside the foundation pit; B. Outside the foundation pit. Detailed Implementation
[0035] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided.
[0036] Please see Figures 1-7 This embodiment provides a pile-anchored deep foundation pit corner support structure, including a plurality of support piles 1. The plurality of support piles 1 are divided into two groups and respectively set on the two right-angled sides of the foundation pit corner area. The two groups of support piles 1 are arranged at equal intervals on the two right-angled sides. The equal interval arrangement is to facilitate the arrangement of the stabilizing mechanism in the following text. The intersection of the two right-angled sides of the foundation pit corner area is the corner point of the foundation pit corner. Each pair of adjacent support piles 1 are connected by a fixing mechanism. The fixing mechanism makes all the support piles 1 along the two right-angled sides of the foundation pit corner area form a whole. A stabilizing mechanism is installed in the foundation pit corner area to prevent the support piles 1 from tilting.
[0037] Currently, in deep foundation pit engineering, anchor cables 5 are installed on both right-angled sides of the corner area during construction. If the anchor cables 5 are installed on the outside B of the foundation pit in the usual way, they are driven into the soil of the limited area of the corner. Since the anchor cable spacing is fixed and the arrangement is dense, the anchor cables 5 on the two right-angled sides will collide and cross in many areas, causing inconvenience during construction. In addition, since both sides of the foundation pit are exposed in the corner area, the soil is cut off by the support structure in two directions. Compared with soil exposed in only one direction, it is more unstable. Under the action of soil pressure in two directions, both sides of the foundation pit in the corner area tend to tilt towards the inside A of the foundation pit. Moreover, the two sides cannot support each other. Therefore, the tilt of the support pile 1 towards the inside A of the foundation pit in the corner area of the deep foundation pit is greater than in other areas, making it the most prone to failure area.
[0038] To address the aforementioned issues, in deep foundation pit engineering, several support piles 1 were first installed on the edges of the two right-angled sides of the pit's external corner area. Then, the support piles 1 were connected into a whole through a fixing mechanism, forming support for the external corner area of the foundation pit. Finally, a stabilizing mechanism was installed in the soil within the external corner area of the foundation pit. Under the action of the stabilizing mechanism, the stability of the external corner area of the foundation pit was further increased. This not only solved the problem of the support piles 1 tilting towards the inner side A of the foundation pit, which is the most prone to damage, but also solved the problem of the anchor cables 5 crossing each other, causing inconvenience in construction.
[0039] In order to better connect several support piles 1 into a whole and thus prevent the support piles 1 from tilting towards the inner side A of the foundation pit, in this embodiment, the fixing mechanism includes two cap beams 2. Each pair of adjacent support piles 1 is connected by two cap beams 2. One of the two cap beams 2 fixes the upper part of the two adjacent support piles 1, and the other cap beam 2 fixes the lower part of the two adjacent support piles 1. The two cap beams 2 are perpendicular to any one of the support piles 1. The cap beams 2 connect all the support piles 1 into a whole.
[0040] To better prevent the support piles 1 from tilting inwards towards the pit A near the vertices of the two right-angled sides in the corner area of a deep foundation pit, in one embodiment, the stabilization mechanism includes a triangular stabilization component. The two right-angled sides of the corner area are extended outwards from their vertices to a point two-thirds of the total length formed by the number of support piles 1. The triangular stabilization component is installed in the section between the vertices and the end point. This is because the soil within this range—from the vertices of the two right-angled sides to two-thirds of the total length formed by the number of support piles 1—has poorer self-stabilization capacity due to its proximity to the corner, the greater impact of the open sides, and the smaller soil space. Therefore, installing the triangular stabilization component in this range makes the "wedge effect" of the newly added piles more significant, achieving the best effect with the most economical arrangement. Furthermore, the triangular stabilization component consists of several newly added piles 3 arranged in a right-angled triangular array, with the spacing between each adjacent newly added pile 3 being twice the length of the support piles. The spacing of the retaining piles 1, where the distance between the newly added pile 3 located at the right angle vertex of the triangular stabilizing component and the two right-angled sides of the pit's external corner area is equal, is twice the spacing of the retaining piles 1. The effect of the equal distance between the newly added pile 3 and the two right-angled sides of the pit's external corner area after alignment is that, after alignment, the two right-angled sides of the right-angled triangle array are parallel to the two right-angled sides of the pit's external corner area, which is equivalent to the gap between the retaining piles 1 and the newly added piles 3 being consistent. This creates a feasible condition for adopting the anchor cable 5 scheme later, because the anchor cables 5 are all drilled and installed between the two piles of the retaining piles 1. If the newly added piles 3 are not aligned with the retaining piles 1, they will encounter the newly added piles 3 during the drilling process of the anchor cables 5 and will not be able to form a hole, and the anchor cables 5 will also not be able to be installed. Secondly, the method of placing them one at a time effectively avoids mutual interference between the newly added piles 3 during construction. It will not damage the soil due to the construction of the newly added piles 3 being too dense, nor will it reduce the strengthening effect of "nailing and wedging" and compaction of the soil due to the excessive spacing.
[0041] To better prevent the support piles 1 from tilting towards the inner side A of the foundation pit in the corner area far from the vertices of the two right angles, in one embodiment, the stabilization mechanism also includes a linear stabilization component. This component is installed along the two right angles of the corner area of the foundation pit, extending outwards from the vertices to a point beyond 2 / 3 of the total length formed by the number of support piles 1. The linear stabilization component consists of a linear array of several newly added piles 3. These newly added piles 3 are divided into two groups and respectively positioned on the extensions of the two right angles of the right-angled triangle array. The distance between any two adjacent newly added piles 3 is twice the spacing of the support piles 1. The distance from the newly added pile 3 at the intersection of the two groups of newly added piles 3 and the extensions of the right angles in the right-angled triangle array to the nearest right angle in the corner area of the foundation pit is twice the spacing of the support piles 1. In this area, the soil outside the pit is supported by the inner soil, and its self-stabilizing capacity is not significantly different from that of soil with only one side exposed. As a transition section, the newly added piles 3 and the support piles 1 on both sides can be arranged in a rectangular pattern within this range, which is both economical and provides a safety reserve.
[0042] To better integrate the newly added piles 3 and the support piles 1 into a solid whole, in one embodiment, each newly added pile 3 in the triangular stabilizing component and the linear stabilizing component is connected by tie beams 4. Tie beams 4 are installed on the newly added piles 3 in the corner area of the foundation pit. Not only are transverse and longitudinal tie beams 4 installed between the newly added piles 3 and the support piles 1, but more importantly, multiple tie beams 4 are installed within a range that forms 2 / 3 of the total length of the support piles 1, arranged in a triangle with the support piles 1 on both sides of the corner. The newly added piles 3 and the support piles 1 within the triangular arrangement area are fixed by the transverse, longitudinal, and 45° tie beams 4 with both sides of the corner area of the foundation pit. The main effects are: 1. By setting transverse and longitudinal tie beams 4, the newly added piles 3 are more securely connected to the support piles 1. 1. Piles 3 and support piles 1 are connected in pairs to form a unified load-bearing structure. 2. Within 2 / 3 of the total length of the support piles 1, multiple tie beams 4 are installed in a triangular arrangement with the support piles 1 on both sides of the external corner. This means that the support piles on both sides of the external corner of the pit are directly connected by tie beams 4 with high rigidity. This ensures that the support piles 1 on both sides of the external corner of the pit are not isolated retaining structures. In other words, when the transverse or longitudinal support piles 1 are subjected to earth pressure and deform towards the inner A side of the pit, the presence of the triangularly arranged tie beams 4 allows the transverse or longitudinal support piles 1 to be interconnected and balance the earth pressure, thus preventing the tops of the transverse or longitudinal support piles from deforming towards the inner A side of the pit. 3. New piles The new pile 3 is surrounded by soil. When the top of the new pile 3 is subjected to tensile force transmitted from the tie beam, the new pile 3 not only resists the tension through its own strength and stiffness, but more importantly, the soil around the new pile provides a stronger tensile resistance. Through the tie beam 4 connecting the new pile 3 and the support pile 1, the new pile 3 provides the support pile 1 with a strong ability to resist earth pressure. Fourth, within a range of 2 / 3 of the total length formed by the number of support piles 1, multiple tie beams are set up in a triangular arrangement with the support piles 1 on both sides of the external corner. The tie beam 4 is supported by multiple new piles 3 and connected to the support piles 1 on both sides, which effectively reduces the span of the tie beam. That is, the tie beam 4 arranged in a triangular arrangement with two tie beams connected in pairs is more effective than the tie beam 4 without the support of new piles 3. With greater stiffness and stronger tensile strength, it can better ensure the stress balance of the two side support piles; Fifth, it makes the newly added pile 3 and the soil in the corner area of the foundation pit form a stable nail-wedge structure together, which is equivalent to driving a stable and very stiff reinforced concrete "nail" into the relatively unstable soil. Through the strong friction between the pile body of the newly added pile 3 and the soil, as well as the compaction effect of the soil during pile driving, which can also be described as the "nail-wedge effect" of the newly added pile 3 on the soil, the self-stabilizing ability of the soil in the corner area of the foundation pit is significantly enhanced, and the soil pressure transmitted from the soil in the corner area of the foundation pit to the two side support piles 1 is reduced, thereby avoiding the support piles 1 from tilting towards the inside A of the foundation pit in the corner area of the deep foundation pit.
[0043] A construction method for a pile-anchored deep foundation pit corner support structure includes the following steps:
[0044] Step S1: Before excavating the external corner of the foundation pit, first determine the external corner area of the foundation pit, and then set the first pile hole at equal intervals along the two right-angled sides of the external corner area of the foundation pit by measurement, and pour the support pile 1 in the first pile hole;
[0045] Step S2: Excavate a trench in the soil between every two adjacent support piles 1, and pour concrete to form two cap beams 2. The two cap beams 2 are fixedly connected to any one of the support piles 1, and the cap beams 2 are used to form a whole with several support piles 1.
[0046] Step S3: Set up the second pile hole in a right triangle array within the area enclosed by 2 / 3 of the length of the two right-angled sides in the area of the external corner of the foundation pit, and pour the new pile 3 in the second pile hole. Set up the third pile hole in a straight line array on the extension line of the two right-angled sides of the right triangle array, and pour the new pile 3 in the third pile hole.
[0047] Step S4: Set up trenches in the soil between every two adjacent newly added piles 3 in the right-angled triangle array and between every two adjacent newly added piles 3 in the straight line array. This forms rows of parallel trenches parallel to the two right-angled sides and the hypotenuse in the right-angled triangle array, and parallel trenches parallel to the straight line array in the straight line array. Pour tie beams 4 into all the parallel trenches and use tie beams 4 to fix the newly added piles 3 in the right-angled triangle array, the newly added piles 3 in the straight line array, and the support piles 1 into a solid whole.
[0048] It also includes the following steps:
[0049] To better address the issue of the support piles 1 tilting inwards towards the pit's inner side (A) in foundation pits with a general depth (h < 10m), where the pit depth refers to the distance from the bottom of the pit to the outer surface (8), in one embodiment, step S5: After completing S1-S4, excavation can proceed along the support piles 1 at the pit's outer corner until excavation is complete, thus completing the construction. All newly added piles 3 have the same diameter as the support piles 1. At this point, the newly added piles 3 within a range covering 2 / 3 of the total length of the support piles 1 are used to connect with the pit's outer corner. The two sides of the area are arranged in a triangle. The number of support piles 1 is set to form a rectangular arrangement of the newly added piles 3 outside the 2 / 3 range of the total length. This technical solution strengthens the soil in the corner area of the foundation pit by "nailing and wedging" and compaction, which significantly enhances the self-stabilization capacity of the soil in the corner area of the foundation pit. Moreover, the soil pressure of the support piles 1 on both sides of the corner of the foundation pit is balanced by the newly added piles 3 and the tie beams 4, so that the deformation of the support piles 1 towards the inside A of the foundation pit is very small. That is, no further treatment measures are required to meet the requirements after adopting this technical solution.
[0050] To better prevent the support piles 1 from tilting inwards towards the pit A in the corner area when the pit depth is relatively deep (10m ≤ pit depth < 15m), in one embodiment, step S6: In step S1, first pile holes are set at equal intervals along the two right-angled sides of the pit corner area by measurement. Here, the first pile hole set on one right-angled side is larger than the first pile hole set on the other right-angled side. An anchor cable 5 is installed in the middle of the support pile 1 on the right-angled side of the pit corner area. The diameter of the support pile 1 on the second side of the pit corner area is larger than the diameter of the support pile 1 on the first side of the pit corner area. The diameter of the support pile 1 on the first side of the pit corner area is the same as the diameter of the newly added pile 3. At this time, if only the newly added pile 3 and tie beam 4 are used, the deformation of the top of the support pile 1 under the action of the newly added pile 3 and tie beam 4 is still very small. However, due to the depth of the pit... The pit is already quite deep, and the deformation in the middle of the pile body cannot be ignored. It can be understood that the top of the retaining pile 1, due to the action of the newly added pile 3 and the tie beam 4, can be considered as the top support of the pile body, and the bottom of the pit, due to the embedment of the soil, can be considered as the bottom support of the retaining pile 1. Therefore, the deformation in the middle area of the retaining pile body under earth pressure is still relatively large. It is necessary to increase the diameter of the retaining pile 1, i.e., increase the strength and stiffness of the retaining pile 1 itself, to resist the large deformation in the middle area of the pile body. Alternatively, while keeping the diameter of the retaining pile 1 unchanged, an anchor cable 5 can be installed in the middle area of the pile body to assist the pile body in resisting deformation under earth pressure. In this case, an anchor cable 5 is installed in the middle of the retaining pile 1 on one side of the pit's external corner, while the retaining pile 1 on the other side of the external corner uses a larger diameter pile body to resist pile body deformation. The main purposes are:
[0051] ①The foundation pit is relatively deep, that is, the middle area of the support pile 1 is relatively far from the top and bottom of the pile. An anchor cable 5 is set in the middle area of the pile. The anchoring effect of the anchor cable 5 can effectively reduce the deformation of the middle part of the pile, which is both economical and has the best effect.
[0052] ② Given the perpendicular geographical shape of the two sides of the external corner of the foundation pit, when anchor cables 5 are installed in the middle area of the pile body of one side support pile 1, if anchor cables 5 are installed on the other side, it will inevitably form an intersection surface in the soil. In addition to the intersection surface, there are many anchor cables 5 on both sides with very close vertical spacing in the soil. The anchor bodies of the anchor cables 5 affect each other, reducing the tensile strength of the anchor cables 5 on both sides. Therefore, it is difficult to achieve the expected effect of reducing the deformation of the middle area of the pile body. Therefore, this technical solution uses a larger diameter pile body on the other side to resist the deformation of the middle area of the pile body. This not only effectively avoids the adverse effects of anchor cables 5 being used on both sides of the external corner of the foundation pit and intersecting with each other, but also ensures that the anchor cables 5 installed have no other structural components in the vertical direction of the soil (i.e., no group anchor effect causing a reduction in anchor tension). The anchor cable 5 has a stronger anchoring force with the soil, thus providing greater tensile strength and more effectively controlling the deformation of the middle area of the pile body.
[0053] ③ According to the principle of force interaction, the anchor cable 5 is subjected to the frictional resistance of the soil, thus forming a tensile force on the anchor cable 5. In turn, the soil is also subjected to an outward tensile force from the anchor cable 5. That is, after being subjected to the tensile force of the anchor cable 5, the soil in the corner area tends to displace towards the inner side A of the foundation pit on the side where the anchor cable 5 is installed. On the side with the increased diameter of the support pile 1, since no anchor cable 5 is installed, the soil is subjected to the tensile force on that side and displaces towards that side. As a result of this effect, the actual deformation in the middle area of the pile body on the side with the increased diameter of the support pile 1 is smaller. That is, anchor cables are only used on one side of the corner of the foundation pit. When anchor cable 5 is installed, the deformation in the middle area of the support pile 1 without anchor cable 5 is reduced in practice. This plays a beneficial role in controlling the deformation in the middle area of the support pile 1 without anchor cable 5, which in turn makes it easier to select the pile diameter of the support pile 1 without anchor cable 5 (i.e., the side with larger support pile diameter). It is easier to achieve both economy and safety. Then, steps S2, S3 and S4 are performed. After step S4, a waist beam 6 is set at the center of the group of support piles 1 with smaller diameter. An anchor cable 5 is installed on the waist beam 6, and finally step S5 is completed.
[0054] To better prevent the support piles 1 from tilting inwards towards the pit A in the corner area when the pit depth is very deep (15m ≤ pit depth h), in one embodiment, step S7: In step S1, the diameter of the first pile holes, which are set at equal intervals along the two right-angled sides of the pit corner area, is greater than the diameter of the first pile hole in step S5. Then, steps S2, S3, and S4 are performed. Then, taking the right-angled vertex of the pit corner area as the starting point and the distance of 2 / 3 of the distribution of one set of support piles 1 as the ending point, a waist beam 6 is set at the center of the support piles 1 between the starting point and the ending point. A waist beam 6 is also set below the center of the support piles 1 outside this interval. Then, in the same way, a waist beam 6 is set at the center of another set of support piles 1. A waist beam 6 is installed both above and below, and a waist beam 6 is installed at the center of the support pile 1 outside this section; at the same time, anchor cables 5 are installed on all waist beams 6, and each waist beam 6 has an installation point for the anchor cable 5. One end of the anchor cable 5 is fixed to the waist beam 6, and the other end is fixed to the bottom of the external corner area of the foundation pit. An anchor cable 5 is installed in the middle of the support pile 1 on the first side of the external corner area of the foundation pit, and two anchor cables 5 are installed on the support pile 1 on the first side of the external corner area of the foundation pit. An anchor cable 5 is installed in the middle of the support pile 1 at a distance of 0.5 times the length of the anchor cable 5 away from the corner point. The diameter of the support pile 1 within the length of the anchor cable 5 is larger than the diameter of the newly added pile 3, and the diameter of the support pile 1 outside the length of the anchor cable 5 is the same as the diameter of the newly added pile 3. The piles and tie beams are used. At this point, the support pile 1 uses a larger diameter pile, twice the diameter of a typical deep support pile 1. However, due to the great depth of the foundation pit and the extremely high earth pressure, the deformation at the top of the support pile 1 is still relatively small due to the addition of the piles and tie beam 4. However, the deformation in the middle and other areas of the pile body is greater under the earth pressure. Because of the reinforcement effect of the addition of piles 3 and tie beam 4, it is not necessary to install a dense array of anchor cables 5 on both sides of the external corner of the foundation pit as is commonly done with pile anchor support. Specifically, an anchor cable 5 is installed in the middle of the transverse support pile at the external corner (where the pile body deformation is greatest). To avoid the influence of the longitudinal anchor cables 5, especially the ends of the anchor cables 5, an anchor cable 5 is installed outside the range that forms 2 / 3 of the total length of the support pile 1. The position of the longitudinal anchor cable is lowered slightly from the middle of the pile body. This ensures that the end of the longitudinal anchor cable is still a large vertical distance from the transverse anchor cable 5, so that the transverse anchor cable 5, which is half the distance away from the corner point, is not adversely affected by the close vertical space caused by the lowering of the end of the longitudinal anchor cable 5 (because the anchor cable 5 is installed at a certain angle downwards, the farther away from the head of the anchor cable 5, that is, the deeper the end of the anchor cable 5 is buried). The transverse anchor cable 5 can directly act on the area of maximum deformation in the middle of the pile body, which can effectively reduce the deformation in the middle of the pile body. Under the combined action of the newly added pile 3, tie beam 4, large-diameter support pile and transverse anchor cable 5, the deformation of the transverse support pile 1 at the corner of the deep foundation pit under the action of earth pressure is small, which meets the requirements.
[0055] In the longitudinal direction of the external corner of the foundation pit, two anchor cables 5 are installed within a distance of 0.5 times the length of the anchor cable 5 from the corner point to avoid affecting the transverse anchor cable 5. Specifically, the first anchor cable 5 is installed above the middle of the pile. To compensate for the reduced effect of the anchor cable 5 not being installed in the area of maximum deformation in the middle of the pile, a second anchor cable 5 is installed at a certain position below the middle of the pile. This second anchor cable 5 is at the bottom of the transverse anchor cable 5 and will not have an adverse effect on the transverse anchor cable 5. At the same time, by setting the second anchor cable 5 together with the first anchor cable 5 to resist tension, the deformation of the pile at the location where the two anchor cables 5 act is effectively reduced. This also indirectly and effectively reduces the deformation in the middle of the pile. A second anchor cable 5 is installed at a distance of 0.5 times the length of the anchor cable 5 from the corner point in the middle of the pile. Anchor cable 5 can avoid the influence of transverse anchor cable 5, and at the same time play a very beneficial role in limiting the deformation of the middle part of the pile. Furthermore, the incident angle of the longitudinal anchor cable 5 at the external corner can be finely adjusted, which is more conducive to avoiding mutual influence of anchor cables 5. Under the combined action of the newly added pile 3, tie beam 4, large-diameter support pile 1 and two longitudinal anchor cables 5, the deformation of the longitudinal support pile 1 at the external corner of the deep foundation pit under the action of earth pressure is small, which meets the requirements. There is only one anchor cable in the transverse direction at the external corner of the deep foundation pit, and two and one anchor cables in the longitudinal direction. Since the foundation pit is very deep, the anchor cables 5 can be flexibly laid out and adjusted within the depth range, and the space between them is sufficient, which can effectively play the anchoring and tensile role of the anchor cables 5 to the soil, thereby effectively reducing the deformation of the pile under the action of earth pressure. Finally, step S5 is completed.
[0056] Working principle and usage process of this invention:
[0057] This invention solves the problem of poor soil stability and susceptibility to damage in the corner area of a deep foundation pit by driving new piles 3 into the soil in a certain pattern within the soil of the corner area of the foundation pit. Specifically, the piles 3 are arranged in a triangular pattern with the two sides of the corner within 2 / 3 of the total length of the support piles 1, and in a rectangular pattern with the two sides of the support piles 1 outside the 2 / 3 of the total length of the support piles 1. At the same time, the new piles 3 are aligned with the support piles 1 and are placed in an alternating pattern. This solves the problem of poor soil stability and susceptibility to damage in the corner area of a deep foundation pit. The new piles 3 have the strengthening effect of "nailing and wedging" and compacting the soil in the corner area of the foundation pit, and create very favorable conditions for the subsequent construction of anchor cables 5.
[0058] Furthermore, by setting tie beams 4 on the newly added piles 3 in the external corner area of the foundation pit, not only are transverse and longitudinal tie beams set between the newly added piles 3 and the support piles 1, but more importantly, multiple tie beams 4 are set within 2 / 3 of the total length of the support piles 1, arranged in a triangle with the support piles on both sides of the external corner. This solves the problem of weak support in the external corner area of the foundation pit and the mutual interference of the transverse and longitudinal anchor cables 5 in the external corner. It realizes the mutual connection and balance of the transverse or longitudinal support piles in the external corner of the foundation pit and creates very favorable conditions for the subsequent construction of anchor cables 5 in deeper foundation pits.
[0059] Furthermore, when the depth of the foundation pit is generally moderate (depth h < 10m), the above-mentioned solution can meet the requirements without further treatment measures. It can effectively solve the problems of weak support in the external corner area of the foundation pit and the mutual influence of the horizontal and vertical anchor cables at the external corner, and achieve the mutual connection and balance of the horizontal or vertical support piles at the external corner of the foundation pit.
[0060] When the foundation pit is deep (10m≤pitsdepthh<15m), it is necessary to use new piles 3, tie beams 4, support piles 1, and to install an anchor cable 5 in the middle of the support pile on one side of the external corner and to change the support pile 1 on the other side of the external corner to a larger diameter pile body. This can effectively solve the problems of weak support in the external corner area of the deep foundation pit and the mutual influence of the horizontal and vertical anchor cables in the external corner. It also achieves the effect that the deformation of the pile top and pile body of the horizontal and vertical support piles in the external corner of the deep foundation pit is small under the action of earth pressure.
[0061] When the foundation pit is very deep (15m≤pitsdepthh), it is necessary to use new piles 3, tie beams 4, larger diameter support piles 1, and to set one anchor cable in the middle of one support pile 1 at the external corner and two and one anchor cables 5 on the other side of the external corner. This can effectively solve the problem of weak support in the external corner area of a very deep foundation pit and the mutual influence of the horizontal and vertical anchor cables 5 at the external corner. It also achieves the effect of small deformation of the pile top and pile body of the horizontal and vertical support piles 1 at the external corner of a very deep foundation pit under the action of earth pressure.
[0062] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A construction method for a pile-anchored deep foundation pit corner support structure, characterized in that, The structure includes several support piles, which are divided into two groups and respectively set on the two right-angled sides of the external corner area of the foundation pit. Each pair of adjacent support piles are connected by a fixing mechanism. A stabilizing mechanism is provided in the external corner area of the foundation pit to prevent the support piles from tilting. The stabilizing mechanism includes a triangular stabilizing component; The stabilizing mechanism also includes a linear stabilizing component; Each newly added pile in the triangular stabilizing component and the linear stabilizing component is connected by a tie beam; The construction method includes the following steps: Step S1: Before excavating the external corner of the foundation pit, first determine the external corner area of the foundation pit, and then set the first pile hole at equal intervals along the two right-angled sides of the external corner area of the foundation pit by measurement, and pour the support pile in the first pile hole. Step S2: Excavate a trench in the soil between every two adjacent support piles, and pour concrete to form two cap beams. The two cap beams are fixedly connected to any one of the support piles, and the cap beams are used to form a whole with several support piles. Step S3: Set up the second pile hole in a right triangle array within the area enclosed by 2 / 3 of the length of the two right-angled sides in the area of the external corner of the foundation pit, and pour the new pile in the second pile hole. Set up the third pile hole in a straight line array on the extension line of the two right-angled sides of the right triangle array, and pour the new pile in the third pile hole. Step S4: Set trenches in the soil between every two adjacent newly added piles in the right triangle array and between every two adjacent newly added piles in the straight line array. This forms rows of parallel trenches parallel to the two right-angled sides and the hypotenuse in the right triangle array, and parallel trenches parallel to the straight line array in the straight line array. Pour tie beams into all the parallel trenches and use the tie beams to fix the newly added piles in the right triangle array, the newly added piles in the straight line array, and the support piles into a solid whole. Step 5: Excavate along the right-angled corner of the foundation pit along the support piles. Then, starting from the right-angled vertex of the corner area, and ending at 2 / 3 of the distance of one set of support piles, install a wainscoting at the center of the support piles between the starting and ending points. Install a wainscoting below the center of the support piles outside this interval. Then, in the same way, install a wainscoting above and below the center of another set of support piles, and install a wainscoting at the center of the support piles outside this interval. At the same time, install anchor cables on all the wainscoting.