Construction method of pre-stressed concrete support enclosure and pre-stressed concrete support enclosure

Abstract

The invention relates to a construction method of a pre-stressed concrete support enclosure and the pre-stressed concrete support enclosure, and belongs to the technical field of building construction. A post-pouring section is arranged on a support beam, and the support beam is pushed by force application equipment, so that the support beam deforms in advance to offset deformation generated by stress of the support beam in the subsequent foundation pit excavation process; therefore, deformation is within an allowable range, alarm and early warning are not generated, the requirement for safe construction of the foundation pit is met, the rigidity of the enclosure structure and the horizontal support can be relatively reduced, steel bars and concrete materials are saved, and the construction cost is saved.

Description

TECHNICAL FIELD

[0001] The present application relates to a pre-stressed concrete support construction method and a pre-stressed concrete support, and belongs to the technical field of building construction. BACKGROUND

[0002] The deep foundation pit support structure includes a vertical support and a horizontal support system. When the foundation pit is excavated, the soil layer inside the retaining structure is excavated, the retaining structure is subjected to the horizontal lateral pressure of the soil body, and the deformation of the foundation pit support structure is increased, and the axial force of the horizontal support system is also increased. In a deep foundation pit with a complex surrounding environment, as the excavation depth gradually increases, the deformation of the support structure and the warning of the support axial force frequently occur.

[0003] The traditional foundation pit horizontal support system generally uses concrete support, which relies on the rigidity of the support beam itself to resist the earth pressure. However, as the excavation depth of the foundation pit increases, the pressure on the inner wall of the foundation pit increases, which leads to excessive deformation of the support structure and the support, and ground cracks and other phenomena occur. The foundation pit monitoring often produces an alarm, which exceeds the specification limit, and there is a risk of failure of the foundation pit support. In order to control the deformation, the cross section of the support beam is often increased, such as an increase of 20% to 30%, to increase the strength of the support body. However, this significantly increases the amount of concrete and steel, which is not economical in terms of engineering cost. Moreover, the stress state of the support beam after forming cannot be adjusted, which makes it difficult to adapt to dynamic construction loads. SUMMARY

[0004] The present application aims to provide a pre-stressed concrete support construction method and a pre-stressed concrete support to solve the above problems.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical solution: a pre-stressed concrete support construction method, the pre-stressed concrete support construction method comprising:

[0006] S1, support beam construction: arranging support beam reinforcement and pouring formwork;

[0007] S2, post-pouring section construction: reserving a post-pouring section on the support beam near the inner wall of the foundation pit, and arranging a support piece near the post-pouring section of the support beam, the width of the post-pouring section being determined according to the pre-stressed design value;

[0008] S3, pre-stressed force application: pouring the support beam and the support piece, and after the concrete strength of the support beam reaches the specified design strength, using a force application device to symmetrically push the support piece towards the post-pouring section, so that the support beam is elastically stretched and deformed towards the post-pouring section until the deformation reaches the set deformation value;

[0009] S4, post-pouring section construction: pouring a pouring material with a strength grade at least one level higher than that of the support beam concrete in the space of the post-pouring section, and vibrating and compacting the pouring material after pouring and curing it to form.

[0010] Further, the support is a bracket, and in step S1, the support beam construction further comprises: arranging pouring bracket reinforcement at the end of the support beam on both sides of the post-cast section, and the bracket reinforcement is reliably connected with the support beam reinforcement, and the same section joint connection rate is not greater than 50%.

[0011] Further, in step S1, the post-cast section and the support beam are arranged with an H-shaped steel and an end plate located at the end of the H-shaped steel, and the H-shaped steel is arranged in the post-cast section and the end of the support beam.

[0012] Further, in step S2, the post-cast section is located in the middle range of one-third of the beam span.

[0013] Further, in step S3, the specified design strength is not less than 80% of the strength of the fully hardened support beam.

[0014] Further, in step S3, the amount of tensile deformation of the support beam is monitored in real time during the pre-tensioning process, and the deformation stability standard is that the deformation increment tends to be zero.

[0015] Further, in step S4, the pouring material of the post-cast section is high-strength grouting material or micro-expansion concrete.

[0016] The application also provides a pre-tensioned concrete support enclosure formed by the above construction method, which comprises vertical supports arranged at the inner wall of the foundation pit and horizontal supports connected between the vertical supports, the horizontal supports comprise a plurality of support beams arranged in a longitudinal and transverse manner, the support beams are arranged with post-cast sections near the inner wall of the foundation pit, the strength of the post-cast sections is at least higher than that of the support beams, and the support beams are provided with support members.

[0017] Further, the support member is a bracket arranged at the end of the support beam near the post-cast section.

[0018] Further, the post-cast section is arranged with an H-shaped steel, and the two ends of the H-shaped steel extend into the support beam and are arranged with end plates.

[0019] The application has the beneficial effects that: by arranging the post-cast section on the support beam and using the force applying device to push the support beam, the support beam is deformed in advance, so as to offset the deformation of the support beam caused by the stress in the subsequent foundation pit excavation process, so that the deformation is within the allowable range, no alarm warning is generated, the requirements of the foundation pit safety construction are met, the rigidity of the enclosure structure and the horizontal support can be relatively reduced, the steel and concrete materials are saved, and the construction cost is saved.

[0020] The application also provides a pre-tensioned concrete support enclosure, which improves the safety of the support beam and saves the construction cost.

[0021] The above description is only a summary of the technical scheme of the present application. In order to make the technical means of the present application more clearly understood and implemented according to the content of the description, the preferred embodiments of the present application are described in detail as follows with reference to the accompanying drawings. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A flow chart of the pre-stressed concrete support enclosure construction method according to an embodiment of the present application;

[0023] Figure 2 A structural schematic diagram of the pre-stressed concrete support enclosure according to an embodiment of the present application;

[0024] Figure 3 A structural schematic diagram of the support beam according to an embodiment of the present application;

[0025] Figure 4 A structural schematic diagram of the support beam according to an embodiment of the present application. DETAILED DESCRIPTION

[0026] The specific embodiments of the present application are described in detail below with reference to the accompanying drawings and embodiments. The following embodiments are used to illustrate the present application, but are not used to limit the scope of the present application.

[0027] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only used to facilitate the description of the present application and simplify the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connection" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0029] Please refer to Figures 1 to 3 The pre-stressed concrete support enclosure construction method according to an embodiment of the present application includes:

[0030] S1, support beam 10 construction: arrangement of support beam 10 reinforcement and pouring formwork;

[0031] S2, post-pouring section 11 construction: reserving post-pouring section 11 on support beam 10 near the inner wall of the foundation pit, and arranging support members near post-pouring section 11 of support beam 10, the width of post-pouring section 11 is determined according to the pre-tension design value;

[0032] S3, pre-tensioning: pouring support beam and support member, after the concrete strength of support beam 10 reaches the specified design strength, using force applying equipment to symmetrically push the support member towards post-pouring section 11, so that support beam 10 produces axial elastic tensile deformation towards post-pouring section 11, until the deformation reaches the set deformation value;

[0033] S4, post-pouring section 11 construction: pouring pouring material with strength grade at least one higher than that of support beam 10 concrete in post-pouring section 11 space, and vibrating and compacting after pouring and curing to form.

[0034] In an embodiment, the support member is a corbel 12, and in step S1, the support beam 10 construction further includes: arranging pouring corbel 12 reinforcement at the end of support beam 10 on both sides of post-pouring section 11, and the corbel 12 reinforcement is reliably connected with the support beam 10 reinforcement, and the same section joint connection rate is not greater than 50%. Indeed, in other embodiments, the support member can also be other fixed structures that can be detachably installed on the support beam 10. The size of corbel 12 is determined according to the size of pre-applied force, which is calculated according to relevant construction standards to ensure that the construction meets the specifications.

[0035] Please refer to Figure 4 In an embodiment, in step S1, H-shaped steel 13 and end plate 14 located at the end of H-shaped steel 13 are arranged between post-pouring section 11 and support beam 10, and H-shaped steel 13 is arranged in post-pouring section 11 and the end of support beam 10. H-shaped steel 13 and end plate 14 are placed in the reinforcement cage formed by the reinforcement of support beam 10 during the arrangement of support beam 10 reinforcement.

[0036] In an embodiment, in step S2, the post-cast section 11 is located in the middle third of the beam span. It should be noted that the beam span is the basic unit of the truss structure, which refers to the section between two adjacent supports in the beam structure, and the support beam 10 is usually composed of multiple beam spans, and the middle third of the beam span refers to the equal division of the length of the beam span into three sections, and the post-cast section 11 is arranged in the middle third section. For a rectangular foundation pit, the post-cast section 11 is mainly arranged at the two ends of the support beam 10 near the inner wall of the foundation pit, and for a square foundation pit, the post-cast section 11 can be arranged on the two ends of all support beams 10. In addition, for a pre-stressed concrete support enclosure composed of multiple horizontal support beams 10, since the uppermost support beam 10 is subjected to small stress and has low risk of cracking, the uppermost support beam 10 can not be provided with a post-cast section 11, and the post-cast section 11 is arranged from the next layer.

[0037] In an embodiment, in step S2, the pre-stress value P is determined according to the following construction specification: P≤k·N k , wherein k is a safety factor (0.5-0.8), and N k is the standard value of the axial tension of the anchor rod or the standard value of the axial pressure of the support.

[0038] In an embodiment, in order to ensure that the deformation caused by the pre-stress is recoverable elastic deformation, in step S3, the specified design strength is not less than 80% of the strength of the fully hardened support beam 10.

[0039] In an embodiment, in step S3, the amount of tensile deformation of the support beam 10 is monitored in real time during the pre-stress application process, and the deformation stability standard is that the deformation increment tends to zero. High-precision displacement sensors are symmetrically installed on the two side corbels 12 to monitor the relative displacement change of the steel plate in the jacking process in real time, and strain gauge arrays are arranged on the surface of the support beam 10 along the axial direction to synchronously collect the surface strain value of the concrete. The actual compression deformation of the support beam 10 is synthesized based on the displacement sensor data and the strain gauge data.

[0040] In an embodiment, in step S4, the casting material of the post-cast section 11 is high-strength grouting material or micro-expansion concrete. The high-strength grouting material is a special building material for bearing extremely low pressure and heavy load, which can bear the same or even higher compressive stress as the existing support beam 10, and the micro-expansion concrete compensates for the shrinkage deformation by generating directional volume expansion to fill the compression gap.

[0041] Please refer to Figure 2 and Figure 3The application further provides a pre-tensioned concrete support enclosure formed by the construction method, which comprises vertical supports arranged at the inner wall of the foundation pit and horizontal supports connected between the vertical supports, the horizontal supports comprising a plurality of support beams 10 arranged in a crisscross manner, the support beams 10 being provided with post-poured sections 11 near the inner wall of the foundation pit, the post-poured sections 11 having a strength at least one level higher than that of the support beams 10, and the support beams 10 being provided with support members.

[0042] In an embodiment, the support member is a corbel 12 arranged at the end of the support beam 10 near the post-poured section 11. The cross section of the corbel 12 is in the shape of a right-angled trapezoid, and the straight angle side is arranged near the post-poured section 11, facilitating the stretching of the support beam 10 by the force applying device to compress the space of the post-poured section 11.

[0043] In an embodiment, the post-poured section 11 is arranged with an H-shaped steel 13, the two ends of the H-shaped steel 13 extending into the support beam 10 and being provided with end head plates 14. The H-shaped steel 13 is arranged in the reinforcement cage of the support beam 10, and is arranged in the post-poured section 11 and the support beam 10 at the two ends of the post-poured section 11 in a three-equal distribution manner. The H-shaped steel 13 increases the connecting strength between the post-poured section 11 and the support beam 10. Of course, the H-shaped steel 13 can also be in other structures, which can be set as required.

[0044] The application has the beneficial effects that: by arranging the post-poured section 11 on the support beam 10 and pushing the support beam 10 by the force applying device, the support beam 10 is deformed in advance to offset the deformation of the support beam 10 caused by the stress in the subsequent foundation pit excavation process, so that the deformation is within the allowable range and no alarm warning is generated, the requirements of the foundation pit safety construction are met, and the rigidity of the support enclosure and the horizontal support can be relatively reduced, the reinforcement and concrete materials are saved, and the engineering cost is saved.

[0045] The application further provides a pre-tensioned concrete support enclosure, which improves the safety of the support beam 10 and saves the construction cost.

[0046] The technical features of the above embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist, they should be considered as the scope of the description.

[0047] The above embodiments only express several implementation manners of the application, and the description is more specific and detailed, but it should not be understood as a limitation on the patent scope of the application. It should be pointed out that, for ordinary skilled persons in the art, some modifications and improvements can be made without departing from the concept of the application, and these all belong to the protection scope of the application. Therefore, the protection scope of the patent of the application should be subject to the appended claims.

Claims

1. A construction method for prestressed concrete support retaining walls, characterized in that, The construction method for the prestressed concrete support retaining structure includes: S1. Construction of support beams: Arrange the reinforcement bars for the support beams and pour the formwork; S2. Construction of the post-cast section: The post-cast section is reserved on the support beam near the inner wall of the foundation pit, and the support components are arranged on the support beam near the post-cast section. The width of the post-cast section is determined according to the prestress design value. S3. Pre-stressing: Cast the support beam and support components. After the concrete strength of the support beam reaches the specified design strength, use force-applying equipment to symmetrically push the support components towards the post-cast section, so that the support beam will produce axial elastic tensile deformation towards the post-cast section until the deformation reaches the set deformation value. S4. Post-cast section construction: Pour a casting material with a strength grade at least one grade higher than that of the supporting beam concrete into the post-cast section space. After pouring, vibrate to compact and cure to shape.

2. The construction method for prestressed concrete support retaining wall as described in claim 1, characterized in that, The support member is a corbel. In step S1, the construction of the support beam further includes: arranging corbel reinforcement bars at the ends of the support beam on both sides of the post-cast section, and ensuring that the corbel reinforcement bars are reliably connected to the support beam reinforcement bars, with the connection rate of joints at the same cross section not exceeding 50%.

3. The construction method for prestressed concrete support retaining wall as described in claim 2, characterized in that, In step S1, an H-beam and a head plate located at the end of the H-beam are arranged between the post-cast section and the support beam. The H-beam passes through the end of the post-cast section and the support beam.

4. The construction method for prestressed concrete support retaining wall as described in claim 1, characterized in that, In step S2, the post-cast section is located within the middle range of one-third of the beam span.

5. The construction method for prestressed concrete support retaining wall as described in claim 1, characterized in that, In step S3, the specified design strength is not less than 80% of the strength of the support beam after it has been fully hardened.

6. The construction method for prestressed concrete support retaining wall as described in claim 1, characterized in that, In step S3, the tensile deformation of the support beam is monitored in real time during the application of prestress, and the deformation stability criterion is that the deformation increment approaches zero.

7. The construction method for prestressed concrete support retaining wall as described in claim 1, characterized in that, In step S4, the pouring material for the post-pouring section is high-strength grout or micro-expansion concrete.

8. A prestressed concrete support retaining structure constructed using the construction method described in any one of claims 1 to 7, characterized in that, The prestressed concrete support enclosure includes vertical supports arranged on the inner wall of the foundation pit and horizontal supports connecting the vertical supports. The horizontal supports include several support beams arranged in a crisscross pattern. The support beams have post-cast sections arranged near the inner wall of the foundation pit, and the strength of the post-cast sections is at least one level higher than that of the support beams. Support members are provided on the support beams.

9. The prestressed concrete support retaining wall as described in claim 8, characterized in that, The support member is a corbel arranged at the end of the support beam near the post-cast section.

10. The prestressed concrete support retaining wall as described in claim 8, characterized in that, H-beams are arranged in the post-cast section, with both ends of the H-beams extending into the support beam and end plates arranged at the ends.

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