阅读说明：本技术 房屋基坑施工斜撑支护方法 (Inclined strut supporting method for house foundation pit construction ) 是由 黄俊澎 卢玉南 郝天之 王龙林 滕中正 于孟生 王�华 莫鹏 廖来兴 于 2021-07-19 设计创作，主要内容包括：本发明适用于建筑施工领域,具体公开了一种房屋基坑施工斜撑支护方法,将传统方法进行优化改进,部分或全部混凝土水平横撑改为三角锥斜撑形式,其原理是在斜撑装置的顶端施加竖向力,从而分解出水平推力作用在隔水帷幕和旋喷桩所组成的防护墙上,斜撑装置施加向下竖向力的方法较为简单,且斜杆分解出来的内力可调；随着基坑的开挖可以增加牵引力从而防止基坑塌陷。与传统的水平横撑相比,在相同支撑效果的要求下,本发明申请的斜撑装置能显著地取代传统的内支撑；具有基坑施工质量好、时间成本低及经济效益好的优点,装置结构简单、施加推力的过程效率高、重量轻。(The invention is suitable for the field of building construction, and particularly discloses a building foundation pit construction diagonal bracing supporting method, which is characterized in that the traditional method is optimized and improved, part or all of a concrete horizontal cross brace is changed into a triangular cone diagonal bracing form, and the principle is that a vertical force is applied to the top end of a diagonal bracing device, so that a horizontal thrust force is decomposed to act on a protective wall consisting of a waterproof curtain and a jet grouting pile, the method for applying a downward vertical force by the diagonal bracing device is simpler, and the internal force decomposed by diagonal rods is adjustable; traction may be increased as the excavation of the excavation occurs to prevent collapse of the excavation. Compared with the traditional horizontal cross brace, the diagonal brace device can remarkably replace the traditional inner support under the requirement of the same support effect; the device has the advantages of good foundation pit construction quality, low time cost and good economic benefit, and has simple structure, high efficiency of the process of applying the thrust and light weight.)

1. The method for supporting the inclined strut for house foundation pit construction is characterized by comprising the following steps of:

s1, arranging a fence, excavating a foundation pit (10) to a preset depth, then arranging support piles along the circumference of the inner wall of the foundation pit (10), and connecting the support piles to form a new protective wall for protecting the inner wall of the foundation pit (10); a plurality of upright posts (23) are arranged on the inner side surrounded by the jet grouting pile (22), and the upright posts (23) are used as stress fulcrums;

s2, preparing a plurality of inclined strut devices (40) and a plurality of traction devices, wherein each inclined strut device (40) comprises a stress piece (42) and four inclined rods (41) hinged to the stress piece (42), and the four inclined rods (41) are in an X-shaped layout;

s3, installing an inclined strut device (40) between the corresponding jet grouting pile (22) and the upright post pile (23), hinging two inclined rods (41) on the same side of the inclined strut device (40) to a protective wall formed by the jet grouting pile (22), hinging two inclined rods (41) on the other side of the inclined strut device (40) to one upright post pile (23) or respectively hinging to the two upright post piles (23), wherein the stress piece (42) is located at a position higher than the inclined rods (41), and arranging a traction device below the stress piece (42) for applying vertical downward traction to the stress piece (42), wherein the traction is transmitted to two sides through the four inclined rods (41) and transmitted to the jet grouting pile (22) and the upright post pile (23) to complete supporting of the inner wall of the foundation pit (10);

and S4, continuously excavating the foundation pit (10), and increasing or reducing the traction force of the traction device according to the deformation and displacement of the soil body around the foundation pit (10) after the worker inspects the foundation pit.

2. The building foundation pit construction diagonal bracing supporting method according to claim 1, characterized in that: a circle of first crown beams (31) are arranged on each jet grouting pile (22), second crown beams (32) are arranged on adjacent upright piles (23), an inclined strut device (40) is arranged between the first crown beams (31) and the second crown beams (32), two inclined rods (41) on the same side of the inclined strut device (40) are hinged to the first crown beams (31), and two inclined rods (41) on the other side of the inclined strut device (40) are hinged to the second crown beams (32).

3. The building foundation pit construction bracing method according to claim 2, characterized in that: and an inclined strut device (40) is arranged between every two adjacent upright piles (23).

4. The building foundation pit construction diagonal bracing supporting method according to claim 3, characterized in that: when the span of the opposite sides of the foundation pit (10) is larger than 50m, a plurality of upright piles (23) are arranged at intervals along the crossing direction of the foundation pit (10), meanwhile, a plurality of inclined strut devices (40) are arranged between two adjacent upright piles (23), and the thrust directions provided by the inclined strut devices (40) are collinear.

5. The building foundation pit construction diagonal bracing supporting method according to claim 1, characterized in that: when the jet grouting pile (22) and the upright post pile (23) are poured, brackets for connecting inclined rods (41) are embedded at positions where inclined strut devices (40) are to be arranged.

6. The building foundation pit construction bracing method according to claim 2, characterized in that: and when the first crown beam (31) and the second crown beam (32) are poured, brackets for connecting inclined rods (41) are embedded at positions where the inclined strut devices (40) are to be arranged.

7. The building foundation pit construction bracing method according to any one of claims 1 to 6, characterized in that: the outer side of the stress piece (42) is hinged with an inclined rod (41), the inner side of the stress piece (42) is connected with the traction device through a traction rope, and when the inclined rod (41) is in a force application state, an included angle between the inclined rod (41) and the horizontal plane is 5-35 degrees.

8. The building foundation pit construction bracing method according to claim 7, characterized in that: the traction device is a tray or a winch or an electric telescopic rod which can be added with a balancing weight.

9. A subway foundation pit supporting method as claimed in claim 1, wherein: setting the traction force of a single inclined strut device to be F, and setting the included angle between each inclined rod and the horizontal plane to be alpha, then setting the horizontal thrust F generated by the four inclined rods of the single inclined strut device_{Level of}The formula is as follows:

Technical Field

The invention belongs to the field of building construction, and particularly relates to a method for supporting a building foundation pit construction diagonal brace.

Background

With the development of economy in China, house construction and construction technology in China is also continuously improved, so that the building level in China is greatly improved. Along with the improvement of living standard of people, the requirement on living quality is higher and higher, a foundation pit supporting construction technology is developed in the building construction, the quality of building construction is effectively improved, and the construction technology of a deep foundation pit is also continuously improved. For the construction process of building construction engineering, the construction process of a foundation pit is complex, and the development of a supporting construction technology of the foundation pit is very important for the building construction engineering in order to ensure the engineering quality and the construction safety. The foundation pit supporting construction technology can guarantee the safety of excavation and construction of a foundation pit and improve the overall quality of building construction.

In the traditional house construction, a foundation pit is excavated to a set depth for multiple times, an inner support (both a concrete structure and a wood structure) is constructed when the foundation pit is excavated to a proper height every time, and the inner support is arranged (dismantled) each time, so that more time and labor are consumed, the construction period is seriously slowed down, and the cost is increased; excavation continues after the inner support of the upper layer is arranged, the inner support of the upper layer can hinder excavation operation of the lower layer, and operation machines avoid complicated inner support troubles. The characteristics and the construction method of the foundation pit support construction in the house construction are analyzed, the effect of the foundation pit support in the house construction is thoroughly understood, and therefore the construction method for supporting by using the deformable structure is provided.

The above background disclosure is only for the purpose of assisting understanding of the inventive concept and technical solutions of the present invention, and does not necessarily belong to the prior art of the present patent application, and should not be used for evaluating the novelty and inventive step of the present application in the case that there is no clear evidence that the above content is disclosed at the filing date of the present patent application.

Disclosure of Invention

The invention aims to provide a bracing and supporting method for building foundation pit construction, which can adjust the supporting force along with the excavation of a foundation pit and can achieve better supporting effect through a single-layer structure compared with the traditional double-layer or three-layer structure.

In order to achieve the aim, the invention provides a building foundation pit construction diagonal bracing support method, which comprises the following steps:

s1, arranging a fence, excavating a foundation pit to a preset depth, then arranging support piles (including waterproof curtains made of waterproof materials and jet grouting piles made of high-strength concrete) along the circumferential periphery of the inner wall of the foundation pit, and connecting the waterproof curtains and the jet grouting piles to form a new protective wall for protecting the inner wall of the foundation pit; and arranging a plurality of upright piles on the inner side surrounded by the jet grouting piles, wherein the upright piles are used as stress fulcrums. Generally, the diameter of the column pile, the size of the reinforcement cage and the depth of the reinforcement cage driven into the ground are all larger. The foundation pit in fig. 1 is approximately rectangular, and in other ways, the foundation pit may be configured to be circular. In other schemes, under the condition of meeting construction requirements such as rigidity and strength, the lattice type upright post can be used for replacing a concrete upright post pile, so that the construction period is further shortened.

S2, preparing a plurality of inclined strut devices and a plurality of traction devices, wherein each inclined strut device comprises a stress piece and four inclined rods hinged to the stress piece, and the four inclined rods are in an X-shaped layout. As shown in fig. 6, the diagonal rod at the upper left corner is collinear with the diagonal rod at the lower right corner, and the diagonal rods at the lower left corner are collinear with the diagonal rods at the upper right corner, so that the forces generated by the paired diagonal rods can be mutually offset, and the stability is improved. As shown in fig. 2, the corners (four positions similar to right angles) of the foundation pit may be arranged in a triangular configuration.

S3, an inclined strut device is installed between the corresponding jet grouting pile and the corresponding upright post pile, two inclined rods on the same side of the inclined strut device are hinged to a protective wall formed by the jet grouting pile, two inclined rods on the other side of the inclined strut device are hinged to one upright post pile or hinged to the two upright post piles respectively, the stress piece is located at a position higher than the inclined rods, one traction device is arranged below the stress piece and used for applying vertical downward traction force to the stress piece, and the traction force is transmitted to two sides through the four inclined rods and transmitted to the jet grouting pile and the upright post pile to complete supporting of the inner wall of the foundation pit.

And S4, continuously excavating the foundation pit, and increasing or reducing the traction force of the traction device according to the deformation and displacement of the soil body around the foundation pit after the worker patrols and examines.

And S5, dismantling the inclined strut device and the traction device after construction is finished.

People need to be dispatched every day to patrol the surrounding environment of the foundation pit, the cracks appearing at the periphery are recorded, cement mortar is adopted to plug in time, grouting and joint filling are carried out if necessary, meanwhile, the places possibly generating water accumulation at the periphery of the foundation pit are treated, and good water dispersing conditions at the periphery of the foundation pit are ensured. The constructor needs to consider the situation of water accumulation in the pit in rainy days which may occur according to the excavation situation of the foundation pit, and requires to prepare a sufficient water pump to ensure that no water accumulation or no pit bubbling is caused at the bottom of the pit in rainy days. Strictly controlling the conditions of pile loading and motor train around the foundation pit, and not allowing the overload of the edge of the foundation pit to exceed the design allowable value; if the stacking load is required to be increased, a design unit is required to be informed to carry out reinforcement treatment on the foundation pit.

As an improvement of the above scheme, a circle of first crown beam is arranged on each jet grouting pile, a second crown beam is arranged on the adjacent upright post pile, an inclined strut device is arranged between the first crown beam and the second crown beam, two inclined rods on the same side of the inclined strut device are hinged to the first crown beam, and two inclined rods on the other side of the inclined strut device are hinged to the second crown beam. The first crown beam and the second crown beam are both cement beams. In the traditional scheme, the crown beam is used for connecting the jet grouting pile and the upright post pile, the jet grouting pile and the upright post pile; in the scheme, the inclined strut device is used for replacing part of the crown beam, so that the internal force of the support is adjustable to cope with the change of the foundation pit. In order to be stressed evenly, as shown in fig. 4, a wale can be arranged on the side surface of the jet grouting pile for connecting the inclined strut device.

As an improvement of the scheme, a diagonal bracing device is arranged between every two adjacent upright piles.

As a modification of the above, when the span of the opposite sides of the foundation pit is greater than 50m, a plurality of upright piles are arranged at intervals in the direction crossing the foundation pit, and a plurality of bracing devices are provided between adjacent two upright piles, and the directions of the thrusts provided by the bracing devices are collinear. As shown in figure 2, six vertical lines are arranged in the middle of the foundation pit, and after the scheme is adopted, the inclined strut devices are connected into a whole to support the two corresponding sides of the foundation pit, so that the force borne by the upright post pile is converted into internal force.

As the improvement of above-mentioned scheme, when pouring jet grouting pile and stand pile, the position that will set up the bracing device is pre-buried and is used for connecting the bracket of down tube, makes things convenient for the later stage to connect.

As the improvement of the scheme, when the first crown beam and the second crown beam are poured, the bracket used for connecting the diagonal rods is embedded at the position where the diagonal bracing device is to be arranged, so that later-stage connection is facilitated. The cross section of the first crown beam and the second crown beam can be set to be rectangular, and compared with a circular jet grouting pile and a vertical column pile, the corbel can be embedded better.

As an improvement of the scheme, the outer side of the stress piece is hinged with an inclined rod, the inner side of the stress piece is connected with the traction device through a traction rope, and when the inclined rod is in a force application state, the inclined rod and a horizontal plane form an included angle of 5-35 degrees. The length of a single inclined rod is 3-5 m.

As an improvement of the scheme, the traction device is a tray or a winch or an electric telescopic rod which can be added with a balancing weight. Taking the tray as an example, the vertical traction force can be increased by adding the balancing weight on the tray; taking a winch as an example, after the winch rotates for a certain angle, the rotation motion is converted into the linear motion of a traction rope through a speed reducer, so that a stress part is slightly pulled to generate different traction forces; taking an electric telescopic rod as an example, the motor drives the screw rod to rotate, and correspondingly the transmission nut descends, so that the traction rope slightly pulls the stress piece to generate different traction forces.

The invention has the following beneficial effects:

the method is characterized in that the traditional method is optimized and researched, and is changed into a triangular-cone inclined strut mode, and the principle is that vertical force is applied to the top end of an inclined strut device, so that horizontal thrust is decomposed to act on a protective wall formed by a waterproof curtain and a jet grouting pile, and the foundation pit collapse is avoided; as another pivot of the diagonal bracing device, the upright post pile needs to maintain enough strength after the pouring is finished.

The method for applying the downward vertical force by the inclined strut device is simple, and the internal force decomposed by the inclined rod is adjustable. Compared with the traditional horizontal cross brace, the diagonal brace device can remarkably replace the traditional double-layer inner support under the requirement of the same support effect; the device has the advantages of good foundation pit construction quality, low time cost and good economic benefit, and has simple structure, high efficiency of the process of applying the thrust and light weight.

Drawings

FIG. 1 is a plan view of a foundation pit with a waterproof curtain and a jet grouting pile according to an embodiment;

FIG. 2 is a plan view of a foundation pit with an embodiment of a post pile and a diagonal bracing arrangement;

FIG. 3 is a side view of an embodiment of a lower jet grouting pile, a stud pile and a diagonal brace device connection;

FIG. 4 is a top view of an example lower swozzle pile, stud pile and diagonal brace device connection;

FIG. 5 is a top view of a first crown beam, a second crown beam, and a brace apparatus coupled according to one embodiment;

FIG. 6 is a block diagram of an embodiment lower diagonal bracing apparatus.

Description of the main reference numerals: 10. a foundation pit; 21. a waterproof curtain; 22. carrying out jet grouting pile; 23. a vertical column pile; 31. a first crown beam; 32. a second crown beam; 40. a bracing device; 41. a diagonal bar; 42. a force-receiving member; 50. a wale.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present invention.

In the description of the present invention, the meaning of a plurality of means is one or more, the meaning of a plurality of means is two or more, and larger, smaller, larger, etc. are understood as excluding the number, and larger, smaller, inner, etc. are understood as including the number. The terms "first", "second" and "third", if any, are used for descriptive purposes only and for distinguishing between technical features and are not to be construed as indicating or implying relative importance or implying a number of indicated technical features or a precedence of indicated technical features.

In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "disposed" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art. The following describes an embodiment of the present invention based on its overall structure.

The traditional foundation pit supporting construction method is introduced, and a foundation pit reconstructed from an old house at a certain position is taken as an example. The depth of the foundation pit 10 is about 9.17-12.20 m. According to the excavation depth, the stratum and the surrounding environmental conditions of the foundation pit 10, the design safety level of the foundation pit 10 support is designed according to the first grade, and the design service life is 1 year. According to the site engineering geology, hydrological conditions and peripheral engineering environment, according to the principles of safety, reliability, advanced technology, economy, reasonability and convenience in construction, and by combining project site conditions, the foundation pit 10 support adopts a support form of a support pile plus two reinforced concrete inner supports, and a three-pipe method high-pressure jet grouting pile 22 water interception curtain form is selected for water interception. The central elevation of the first-channel inner support is 74.76m, and the central elevation of the second-channel inner support is 71.30 m. Note: the "0" point reference of the center elevation is the bottom of the jet grouting pile 22, and does not indicate the depth of the foundation pit 10, and in this embodiment, it can be understood that two inner supports are arranged on the middle layer and the middle upper layer of the foundation pit 10.

The traditional construction method comprises the following steps:

s1, after the arrangement of the enclosure, the pipeline migration or the protection is finished, the construction of a foundation pit 10 can be carried out, the whole field is excavated to 75.16m, the support pile, the jet grouting pile 22 and the upright post pile 23 are firstly constructed according to design requirements, then the construction of a crown beam and a slope top drainage ditch is carried out, and then the earthwork is excavated to 74.26m to carry out the construction of a first inner support beam.

S2, after the construction of the first inner support is finished and the concrete strength reaches 80%, earth is excavated to 70.80m, and then the second inner support and the waist beam are constructed.

And S3, after the construction of the second inner support is finished and the concrete strength reaches 80%, earth is excavated to 66.20m and 65.20m, and a foundation part is constructed.

And S4, after the construction of the negative three-layer top plate of the basement is finished, removing the second inner support after the strength of the concrete of the floor slab reaches 80%.

And S5, after the construction of the basement negative second-layer top plate is completed and the strength of the floor slab concrete reaches 80%, removing the first inner support and cutting off the stand columns between the floor slabs.

Returning to the application of the invention, the construction method improved on the basis is as follows:

s1, after the arrangement of the enclosure, the pipeline migration or the protection is finished, the construction of a foundation pit 10 can be carried out, the whole field is excavated to 75.16m, the support piles, the jet grouting piles 22 and the upright piles 23 are firstly constructed according to design requirements, then the construction of a crown beam and a slope top drainage ditch is carried out, and then earth is excavated to 74.26m to carry out the construction of a supporting beam. The internal support construction comprises the steps of arranging upright piles 23, arranging inclined strut devices 40 at corresponding positions according to design requirements, and applying proper traction force through traction devices (one inclined strut device 40 is arranged between the corresponding upright pile and the upright pile 23, two inclined rods 41 at the same side of the inclined strut device 40 are hinged to a protective wall formed by the upright pile (both a waterproof curtain and a jet grouting pile 22), two inclined rods 41 at the other side of the inclined strut device 40 are hinged to one upright pile 23 or are respectively hinged to two upright piles 23, a stress element 42 is positioned at a position higher than the inclined rods 41, one traction device is arranged below the stress element 42 and is used for applying vertical downward traction force to the stress element 42, and the traction force is transmitted to the two sides through the four inclined rods 41 and is transmitted to the upright pile and the upright pile 23 to complete the support of the inner wall of the foundation pit 10).

S2, after the inner support completes construction and applies proper traction force, earth is excavated to 70.80m, then the traction force applied by the traction device is increased, and the initial position of the inclined support device 40 is unchanged but the internal force is increased.

And S3, constructing a top plate of the negative three-layer of the basement, constructing a top plate of the negative two-layer of the basement after the strength of the floor concrete reaches 80%, dismantling the first inner support after the strength of the floor concrete reaches 80%, and cutting off the stand columns between the floors.

The principle of the bracing device 40 used in the present application is shown in fig. 3, and a vertical force F is applied to the force-receiving member 42, and a horizontal and lateral force generated by the diagonal rod 41 is calculated, and then a mechanical analysis is performed. As can be seen from the geometrical configuration, the vertical force applied to each diagonal rod 41 is 0.25F, and the horizontal force generated by each diagonal rod 41 is set to be F_{Level of}Then:

alpha-angle of projection of the diagonal 41 from the horizontal.

In practical design, the inclined rod 41 is one of the pressure rods, and needs to consider the conditions of temperature, flexibility, deformation and the like, for example, after the inclined rod 41 is stressed, a very small amount of stress points move downwards, and the rod body bends or compresses to be shortened. Therefore, the part needs to be checked before construction.

The angle of the diagonal 41 projected from the horizontal is calculated at 15. When the foundation pit 10 is excavated to 74.26m, the internal force applied to a certain concrete beam in the traditional scheme is about 6kN, and the traction force required to be applied by adopting the scheme is about 300 kN; when the foundation ditch 10 excavates 70.80m, the internal force that certain concrete beam in the traditional scheme received is about 11kN, and this scheme of adoption only need increase traction force to about 500kN can, convenient operation. The pressure between the inner side of the foundation pit 10 and the protective wall is basically in direct proportion to the excavation depth, and the traction force can be dynamically and slowly increased to 500kN in the excavation process.

As the single upright post beam can not bear the corresponding reaction force, in case of accident, the adjacent upright post beams are also connected to form a whole to share the reaction force together.

The traditional method is optimized and researched, and is changed into a triangular-cone inclined strut form, and the principle is that a vertical force is applied to the top end of an inclined strut device 40, so that the horizontal thrust is decomposed to act on a protection wall formed by a waterproof curtain 21 and a jet grouting pile 22, and the foundation pit 10 is prevented from collapsing; as another pivot of the bracing device 40, the stud 23 needs to maintain sufficient strength after the casting is completed.

The method of applying a downward vertical force by the diagonal bracing device 40 is simple, and the internal force of the diagonal rod 41 is adjustable. Compared with the traditional horizontal cross brace, the diagonal brace device 40 can obviously replace the traditional inner brace under the requirement of the same support effect; the foundation pit 10 construction device has the advantages of good construction quality, low time cost and good economic benefit, and is simple in structure, high in thrust applying process efficiency and light in weight.

The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims and their equivalents.