Prestressed string-ring support system and its deformation control method

Abstract

The present invention discloses a prestressed tensioned circular ring support system and a deformation control method thereof, the system comprises a circular ring support constructed in a foundation pit, and tensioned strings arranged along the diameter direction of the circular ring support, the tensioned strings are multiple, the angles between two adjacent tensioned strings are the same, and at least one intersection point between the tensioned strings or their extension lines and the circular ring support is provided with a prestressing device. The deformation control method, when the foundation pit deforms in a certain direction or a relative direction causing the circular ring support to deform in the same direction, adjusts the prestress applied to the circular ring support by the prestressing device corresponding to the tensioned strings perpendicular to the deformation direction, so that the deformation of the circular ring support is controlled. The present invention can control the deformation of the prestressed tensioned circular ring support system caused by the deformation of the foundation pit, so as to protect the facilities around the foundation pit.

Description

Technical Field

[0001] The invention relates to the technical field of building engineering, and in particular to a prestressed string-type circular ring support system and a deformation control method thereof. Background Art

[0002] With the advancement of urbanization, the demand for expanding the underground space of existing buildings is increasing. The excavation depth of such projects is usually more than ten meters or even thirty meters, and the project is close to residential, commercial, municipal roads, subways, municipal pressure pipelines and other facilities. In order to ensure that the deformation of surrounding facilities can be controlled during the foundation pit construction, the deformation of the foundation pit support system must be strictly limited. In this field, the support system in the foundation pit often adopts the following technical means:

[0003] 1. Increase the rigidity of the retaining wall, such as increasing the cross-sectional area of ​​the retaining piles, or using underground continuous walls with greater rigidity;

[0004] 2. Use internal support materials with greater rigidity, such as high-strength concrete materials to replace steel pipes and H-shaped steel supports;

[0005] 3. Increase the cross-sectional area of ​​the internal support system;

[0006] 4. Reduce the vertical support distribution spacing, such as using a multi-channel vertical internal support system to control the calculated length of the retaining wall.

[0007] The defects of the above-mentioned technical means are as follows:

[0008] (1) The cost of the enclosure system has increased dramatically. Increasing the rigidity of the enclosure wall, reducing the vertical support distribution spacing, and increasing the internal support cross-section will increase the amount of enclosure engineering and increase the cost of the foundation pit.

[0009] (2) Extension of construction period: Excessive construction volume increases construction period and places higher demands on the flexible allocation of resources such as construction materials, manpower, and machinery and equipment;

[0010] (3) The stiffness of the internal support is seriously attenuated as the length of the in-plane support increases;

[0011] (4) The construction process of the enclosure system will generate a large amount of dust and sewage. At the same time, a large amount of construction waste is difficult to recycle, causing environmental pollution. Summary of the invention

[0012] The technical problem to be solved by the present invention is to provide a prestressed string-type circular ring support system and a deformation control method thereof, so as to control the deformation of the prestressed string-type circular ring support system when the foundation pit is deformed, and protect the facilities around the foundation pit.

[0013] In order to solve the above technical problems, the technical solution of the present invention is: a prestressed tensioned circular ring support system, including a circular ring support constructed in a foundation pit, and tensioned strings arranged along the diameter direction of the circular ring support, the tensioned strings are multiple, the angles between two adjacent tensioned strings are the same, and a prestressing device is provided at at least one intersection point of the tensioned strings or their extended lines with the circular ring support.

[0014] Furthermore, in the prestressed string-tensioned circular ring support system provided by the present invention, the prestress applying device is a jack.

[0015] Furthermore, in the prestressed tensioned circular ring support system provided by the present invention, the prestress applying device is an electric motor, and the electric motor is connected to the tensioned string via a lead screw.

[0016] Furthermore, in the prestressed tensioned circular ring support system provided by the present invention, the prestress applying device is arranged on the inner side, outer side of the circular ring support or penetrates the inner and outer sides of the circular ring support.

[0017] Furthermore, in the prestressed tensioned circular ring support system provided by the present invention, the tensioned strings are steel strands, steel pipes, steel bars or a combination thereof.

[0018] Furthermore, in the prestressed tensioned circular ring support system provided by the present invention, the angle between two adjacent tensioned strings is an acute angle.

[0019] Furthermore, in the prestressed tensioned string circular ring support system provided by the present invention, the tensioned string is provided with multiple layers in the radial direction of the circular ring support.

[0020] Furthermore, in the prestressed tensioned circular ring support system provided by the present invention, the circular ring support is cast by concrete on-site; or the circular ring support is assembled by precast concrete; or the circular ring support is assembled by steel components.

[0021] Furthermore, in the prestressed tensioned string circular ring support system provided by the present invention, the tensioned string may or may not penetrate the circular ring support.

[0022] In order to solve the above technical problems, the technical solution of the present invention is: a deformation control method for the prestressed tensioned circular ring support system as mentioned above, when the foundation pit is deformed in a certain direction or a relative direction causing the circular ring support to deform in the same direction, the prestress applied to the circular ring support is adjusted by the prestress applying device corresponding to the tensioned string perpendicular to the deformation direction, so that the deformation of the circular ring support is controlled.

[0023] Compared with the prior art, the prestressed tensioned circular ring support system and its deformation control method of the present invention are composed of a circular ring support and a plurality of tensioned strings distributed in the diameter direction of the circular ring support, and at least one intersection point of the tensioned strings and the circular ring support is provided with a prestressing device, which has the effect of simple structure and low cost. The deformation control method adjusts the tensioning force of the tensioned strings through the prestressing device to adjust the prestress applied to the circular ring support, so as to improve the rigidity of the circular ring support and keep the prestressed circular ring support system stable. When the circular ring support is deformed, the prestressing device corresponding to the tensioned strings perpendicular to the deformation direction is used to adjust the prestress applied to the circular ring support, so that the deformation of the circular ring support is controlled, thereby controlling the deformation of the foundation pit and protecting the facilities around the foundation pit. The prestressed tensioned circular ring support system and deformation control method thereof of the present invention do not need to increase the rigidity of the retaining wall, do not need to increase the cross-sectional size of the internal support system, do not need to reduce the vertical support distribution spacing, do not need to use support materials with greater rigidity, and will not cause environmental pollution due to the increase of the above-mentioned construction. It has the effects of simple structure, convenient deformation control, energy saving and environmental protection, low cost, and short construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figures 1 to 5 It is a top view structural diagram of the prestressed string circular ring support system;

[0025] Figure 6 It is a side view structural diagram of a prestressed string circular ring support system;

[0026] Figure 7 It is a schematic diagram of the deformation control principle of the prestressed tensioned circular ring support system.

[0027] As shown in the figure: 100, prestressed tensioned circular ring support system, 110, circular support, 120, tensioned string, 130, prestressing device, 200, ground, 300, foundation pit. DETAILED DESCRIPTION

[0028] The present invention is described in detail below in conjunction with the accompanying drawings:

[0029] Please refer to Figure 1 and Figure 6 An embodiment of the present invention provides a prestressed tensioned circular ring support system 100, comprising a circular ring support 110 constructed in a foundation pit 300, and tensioned strings 120 arranged along the diameter direction of the circular ring support 110, wherein there are multiple tensioned strings 120, and the angles between two adjacent tensioned strings 120 are the same, and a prestressing device 130 is arranged at at least one intersection point of the tensioned strings 120 or their extended lines and the circular ring support 110.

[0030] The construction method of the prestressed tensioned circular ring support system 100 of the embodiment of the present invention is as follows:

[0031] Step 101 , constructing a circular support 110 in a foundation pit 300 .

[0032] Step 102 , after the circular support 110 reaches the construction strength, a tensioning string 120 is arranged along the diameter direction of the circular support 110 and with both ends intersecting on the circular support 110 .

[0033] Step 103 , a prestressing device 130 is provided at at least one intersection point between the tension string 120 and the annular support 110 .

[0034] Step 104 , adjusting the tension of the tension string 120 through the prestress applying device 130 to adjust the prestress applied to the circular support 110 , so as to form a prestressed circular support system 100 in the foundation pit 300 .

[0035] Of course, the prestressed string-tensioned circular ring support system 100 of the embodiment of the present invention and the foundation pit enclosure provided in the foundation pit 300 are provided with support structures and methods known in the art. For example, the circular support 110 and the underground continuous wall of the foundation pit enclosure are supported by support rods. That is, the prestressed string-tensioned circular ring support system of the embodiment of the present invention cooperates to bear the external load. In addition, the prestressed string-tensioned circular ring support system 100 of the embodiment of the present invention is not limited to rectangular foundation pits, but is more suitable for circular foundation pits.

[0036] Please refer to Figure 1 and Figure 7 In the deformation control method of the prestressed tension string 120 circular support system 100 of the embodiment of the present invention, when the foundation pit 300 deforms in a certain direction or a relative direction, causing the circular support 110 to deform in the same direction, the prestress applied to the circular support 110 is adjusted by the prestress applying device 130 corresponding to the tension string 120 perpendicular to the deformation direction, so that the deformation of the circular support 110 is controlled. For example, the diameter size of the circular support 110 is plastic, and the deformation of the circular support is controlled by adjusting the tension force of the tension string 120 by the prestress applying device 130 to reduce or increase the diameter size of the circular support 110.

[0037] The prestressed tension string 120 circular support system 100 and its deformation control method of the embodiment of the present invention are composed of a circular support 110 and a plurality of tension strings 120 distributed in the diameter direction of the circular support 110. At least one intersection point of the tension string 120 and the circular support 110 is provided with a prestress applying device 130, which has the effect of simple structure and low cost. The deformation control method adjusts the tensioning force of the tension string 120 through the prestress applying device 130 to adjust the prestress applied to the circular support 110, so as to improve the rigidity of the circular support 110 and keep the prestressed circular support system 100 stable. When the circular support 110 is deformed, the prestress applied to the circular support 110 is adjusted by the prestress applying device 130 corresponding to the tension string 120 perpendicular to the deformation direction, so that the deformation of the circular support 110 is controlled, thereby controlling the deformation of the foundation pit 300 and protecting the surrounding facilities of the foundation pit 300. The prestressed tensioned 120 circular ring support system 100 and deformation control method thereof of the embodiment of the present invention do not need to increase the stiffness of the retaining wall, do not need to increase the cross-sectional size of the internal support system, do not need to reduce the vertical support distribution spacing, do not need to use support materials with greater stiffness, will not cause environmental pollution due to the increase of the above-mentioned construction, and have the effects of simple structure, convenient deformation control, energy saving and environmental protection, low cost, and short construction period.

[0038] Please refer to Figure 7 , taking the circular support 110 with a diameter of 100m as an example, the cross-sectional size of the circular ring is 1200mm×800mm, the concrete strength grade is C35, a tension string is set every 30° in the circular support, the tension force F of the tension string is designed to be 500kN, and the dimensional deformation is δm. Calculated by the finite element software (Abaqus), the radial stiffness coefficient of the circular support 110 is k=F / δ=1673.7kN / m. The conventional concrete bracing support system in this field has a stiffness of 1493.3kN / m. It can be seen that the prestressed tension string 120 circular support system 100 of the embodiment of the present invention is improved by about 12% in overall stiffness. Therefore, it has the effect of strong rigidity, good integrity, and can bear eccentric loads. The angles between the two adjacent tension strings are the same in order to improve the deformation control accuracy of the circular support. The tensioning force of the plurality of tension strings 120 is adjusted by the corresponding prestressing device 130 so that the annular support 110 is evenly stressed, thereby achieving the purpose of balancing and accurately controlling the deformation of the annular support 110 .

[0039] The prestressed tensioned 120 circular ring support system 100 of the embodiment of the present invention has a small support cross-sectional size under the same stiffness conditions, generates less waste construction waste after dismantling, and has the effect of energy saving and environmental protection.

[0040] Please refer to Figure 1In the prestressed tension string 120 ring support system 100 provided by the embodiment of the present invention, the prestressing device 130 can be a jack. One end of the jack is connected to the ring support 110, and the other end is connected to the tension string 120. The two ends of the jack refer to the ejection end and the base. The jack is, for example, a hydraulic jack. When the prestressing device 130 is a jack, it has the advantages of easy installation, easy control, and stable adjustment.

[0041] Please refer to Figure 1 In the prestressed tension string 120 ring support system 100 provided by the embodiment of the present invention, the prestressing device 130 is a motor, and the motor is connected to the tension string 120 through a screw. For example, one end of the tension string 120 is set as a screw structure, including a screw and a nut. For stable control, the motor can be a stepper motor.

[0042] Please refer to Figures 2 to 4 In the prestressed string 120 circular support system 100 provided by the embodiment of the present invention, the prestressing device 130 is arranged on the inner side, outer side or through the inner and outer sides of the circular support 110. Figure 2 The prestressing device 130 is arranged on the inner side of the annular support 110. Figure 3 The prestressing device 130 is arranged outside the annular support 110. Figure 4 The prestressing device 130 in the embodiment penetrates the inner and outer sides of the annular support 110. In other words, the position relationship of the prestressing device 130 can be set as long as the tensioning force of the tensioning string 120 can be adjusted and applied to the annular support 110.

[0043] Please refer to Figures 1 to 4 In the prestressed tension string 120 circular support system 100 of the embodiment of the present invention, the tension string 120 can penetrate the circular support 110 and extend outside the circular support 110. Please refer to Figure 5 , the tension string 120 can be arranged on the inner side of the circular support 110 or pass through the circular support 110 and not extend to the outer side of the circular support 110. That is, the tension string 120 can pass through the circular support 110 or not, as long as the tensioning force of the tension string 120 can be adjusted and applied to the circular support 110. Among them, the tension string 120 can be a steel strand, a steel pipe, a steel bar or a combination thereof. The tension string 120 of the embodiment of the present invention is preferably a steel strand, which is a soft and bendable material and has the advantages of easy handling, easy adjustment and easy installation.

[0044] Please refer to Figures 1 to 5In the prestressed tension string 120 circular ring support system 100 provided in the embodiment of the present invention, the angle between two adjacent tension strings 120 is an acute angle. For example, there are four tension strings, and two adjacent tension strings form an acute angle of 30 degrees. However, the number of tension strings in the embodiment of the present invention is not limited to 4, and can be adjusted according to environmental requirements.

[0045] Please refer to Figure 6 In the prestressed tension string 120 circular ring support system 100 provided by the embodiment of the present invention, the tension string 120 is provided with multiple layers in the radial direction of the circular ring support 110. The structure of each layer of tension string 120 can be the same or different. The deformation of the circular ring support 110 located in the foundation pit 300 of different depths at different axial positions is controlled by the multiple layers of tension string 120 to improve the control accuracy.

[0046] Please refer to Figure 1 , the prestressed tension string 120 ring support system 100 provided by the embodiment of the present invention, the ring support 110 can be cast in situ with concrete. Please refer to Figures 2 to 5 The circular support 110 can be assembled from precast concrete or steel components. The use of precast concrete or steel components has the effect of shortening the construction period and improving the construction progress.

[0047] The present invention is not limited to the above specific embodiments, and all changes and modifications made within the claims of the present invention are within the protection scope of the present invention.

Claims

1. A prestressed string ring support system, characterized in that: It includes a circular ring support constructed in a foundation pit, and a tension chord arranged along the diameter direction of the circular ring support, wherein the tension chord is arranged in multiple layers in the axial direction of the circular ring support, each layer of the tension chord is a plurality of chords intersecting at one point, and the angles between two adjacent chords are the same as acute angles, and a prestressing device is arranged at at least one intersection point between the chord or its extension line and the circular ring support; the tensioning force of the tension chord is adjusted by the prestressing device to adjust the prestress applied to the circular ring support, so as to form a prestressed circular ring support system in the foundation pit.

2. The prestressed string-ring support system according to claim 1, characterized in that: The prestressing device is a jack.

3. The prestressed string-ring support system according to claim 1, characterized in that: The prestressing device is an electric motor, and the electric motor is connected to the tensioning string through a lead screw.

4. The prestressed string-ring support system according to claim 1, characterized in that: The prestressing device is arranged on the inner side or the outer side of the circular ring support or penetrates the inner and outer sides of the circular ring support.

5. The prestressed string-ring support system according to claim 1, characterized in that: The tension string is a steel strand, a steel pipe, a steel bar or a combination thereof.

6. The prestressed string-ring support system according to claim 1, characterized in that: The circular ring support is formed by pouring concrete on site; or the circular ring support is assembled from prefabricated concrete; or the circular ring support is assembled from steel components.

7. The prestressed string-ring support system according to claim 1, characterized in that: The tension string passes through or does not pass through the circular ring support.

8. A deformation control method for a prestressed string-ring support system according to any one of claims 1 to 7, characterized in that: A support structure is arranged between the prestressed tensioned circular ring support system and the foundation pit enclosure arranged in the foundation pit. When the foundation pit is deformed in a certain direction or a relative direction causing the circular ring support to deform in the same direction, the prestress applied to the circular ring support is adjusted by a prestress applying device corresponding to the tensioned string perpendicular to the deformation direction. The deformation of the circular ring supports at different axial positions in foundation pits at different depths is controlled by multiple layers of tensioned strings, so that the deformation of the circular ring supports is controlled, thereby controlling the deformation of the foundation pit and protecting the facilities around the foundation pit.

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