CN107326898B - I-shaped precast pile supporting structure with adjustable inserted rigidity in cement-soil wall and construction method thereof - Google Patents
I-shaped precast pile supporting structure with adjustable inserted rigidity in cement-soil wall and construction method thereof Download PDFInfo
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- CN107326898B CN107326898B CN201710758986.2A CN201710758986A CN107326898B CN 107326898 B CN107326898 B CN 107326898B CN 201710758986 A CN201710758986 A CN 201710758986A CN 107326898 B CN107326898 B CN 107326898B
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Abstract
The invention discloses a rigidity-adjustable I-shaped precast pile supporting structure inserted in a cement-soil wall, which comprises the cement-soil wall for stopping water and a rigidity-adjustable I-shaped precast pile which is arranged in the cement-soil wall and used for retaining soil; the top end of the rigidity-adjustable I-shaped precast pile is provided with a concrete crown beam; the ratio of the short edge to the long edge of the pile body of the rigidity-adjustable I-shaped precast pile is 0.55-0.6; the grade of the strength of the concrete of the pile body of the rigidity-adjustable I-shaped precast pile is C55-C80. The cement soil wall has the advantages of wide applicable strata, small discreteness, high strength, uniform upper and lower strength and good waterproof performance; the supporting structure is simple to operate, convenient, rapid and reliable to construct, and simultaneously gives full play to the characteristics that the rigidity-adjustable I-shaped precast pile has high concrete strength grade and the prestress can be adjusted on site, so that the purposes of shortening the construction period and reducing the construction cost are achieved, the using amount of concrete and steel can be reduced, and the safety requirement can be met.
Description
Technical Field
The invention relates to the field of civil engineering, in particular to a supporting structure and a construction method for inserting an I-shaped precast pile with adjustable rigidity into a cement soil wall, which are suitable for supporting and treating deep foundation pits in constructional engineering, embankment engineering, road engineering and subway engineering.
Background
The wall-forming construction of cement-soil wall is characterized by that it utilizes the machine with chain saw type cutter box to vertically insert said cutter box into ground layer, then makes horizontal transverse movement, at the same time utilizes chain to drive cutter to make up-and-down rotary movement, and can stir and mix original soil and can pour cement paste so as to form the channel-type cement-soil stirring wall with uniform thickness. The method is mainly characterized by continuous wall forming, smooth surface, consistent thickness and good uniformity of the wall body, and is applied to foundation reinforcement and seepage-proofing treatment of various underground projects.
The foundation pit engineering faces not only seepage prevention and water stop but also excavation and soil retaining, but the foundation pit supporting structure serving as a temporary structure is short in utilization period and high in cost. Therefore, shortening the construction period of the foundation pit and reducing the cost of the supporting structure become problems to be solved. In engineering, a method of implanting H-shaped steel into a triaxial cement soil mixing pile to form a composite soil and water retaining structure is usually adopted, namely, a method of firstly mixing soil by using the triaxial cement soil mixing pile and then implanting H-shaped steel before initial setting of cement soil is utilized. However, this method has the following drawbacks: (1) The consumption of H steel is large, the transportation and lease cost of the H steel is increased along with the increase of the scale of the foundation pit, the H steel is not economical, and after the construction of the basement is finished, the H steel needs to be pulled out, so that the H steel is damaged by bending, tension cracking and the like, and when the H steel cannot be pulled out, the supporting cost is greatly increased; (2) The stirring piles have certain distance between the axial centers of the piles, and when the H-shaped steel is implanted, the distance is certain, and cannot be adjusted according to the requirement, so that the supporting method does not meet the requirements of the design on bending resistance and shearing resistance of a supporting structure under many conditions, and the pile length in a deep foundation pit also does not meet the requirements of the design on the embedding depth.
The Chinese patent application with the patent application number of 201110460244.4 discloses a cast-in-place I-shaped reinforced concrete and cement soil alternate underground continuous wall and a construction method thereof, which is characterized in that the cast-in-place I-shaped reinforced concrete is a pipe sinking cast-in-place pile with an I-shaped cross section, and alternate cement soil is a cement jet grouting pile or a cement stirring pile. Although this method has no mud pollution, it has the following disadvantages: (1) The I-shaped pile is cast in place, and the maintenance time is too long, so that the construction period is influenced; (2) The cast-in-place concrete has lower grade, the pile body has lower rigidity after pile forming, and the deformation resistance is too poor; (3) The soil squeezing phenomenon exists in the process of filling the immersed tube into the hole, and soil squeezing displacement and deformation can be generated on pipelines and buildings which are sensitive to deformation at the periphery of a field, so that the influence is large.
The Chinese application patent with the application number of 201310030440.7 discloses a method for inserting a cast-in-place post-tensioned H-shaped pile into cement soil, which comprises the following steps: measuring lofting, and positioning the position of the pile body according to a known coordinate base point; ditching and digging grooves, ditching and digging grooves corresponding to the construction position of the pile machine, and cleaning redundant soil; setting a guide, namely setting a section steel guide at a specific position of the pile body; the pile driver is in place: erecting the pile machine at a specific construction position; stirring to form a pile: forming an I-shaped pile body by using cement soil; inserting a pile body: inserting the I-shaped pile body into the soil body; moving the machine: and after the construction of the I-shaped pile body is finished, moving the pile machine, and carrying out the next construction. Although the method has the characteristic of scale manufacturing, and can avoid the situations of peripheral building and environmental settlement and cracking caused by the extraction of the section steel, the method has the following defects: (1) The construction method of the specific size and the prestress of the post-tensioned H-shaped pile is not mentioned, and the construction site is difficult to realize; (2) The cement soil pile forming method is not clear, the size is not clear, and the construction site cannot be implemented; (3) The inner inserting distance of the I-shaped pile is not clear, and the construction site cannot be determined; (4) The rigidity of the I-shaped pile can not be adjusted according to the field requirement, and the aim of increasing the rigidity and reducing the displacement can not be achieved.
Therefore, a supporting structure of a foundation pit and a construction method thereof are urgently needed, wherein the supporting structure of the foundation pit can fully utilize the water stop effect of the cement-soil piles, can form the construction period of a retaining supporting structure in a short time, can effectively control the deformation of the foundation pit by adjusting the rigidity at any time according to the engineering field, and has the advantages of cost and construction period.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention provides an I-shaped precast pile supporting structure with adjustable insertion rigidity in a cement-soil wall and a construction method, which change the pile forming method of the original cement-soil pile on the basis of the thought of the pile in the traditional SMW construction method and the insertion of the I-shaped pile in the traditional cement-soil mixing pile to form the continuous cement-soil wall with the same thickness, and simultaneously improve the problems that the rigidity of the original precast pile is not adjustable and the rigidity of the supporting pile cannot be adjusted in time according to the deformation of a foundation pit. In the engineering site, before the initial setting of the channel type cement-soil mixing wall, the I-shaped precast pile applied with the initial prestress is hoisted by a crane and inserted into the cement-soil wall. The distance between the I-shaped precast piles is flexibly set according to design requirements, after pile insertion is completed, other construction procedures are consistent with those of common foundation pit supporting engineering, but the rigidity of the I-shaped precast piles can be adjusted through monitoring the condition of horizontal displacement of the deep layer of the soil body in the foundation pit construction process, the rigidity of the supporting piles is increased, and further development of deformation is reduced. The channel type I-shaped precast pile supporting structure with adjustable inserted rigidity in the cement soil wall can solve the problem that the length of a traditional water stop pile is insufficient, can also solve the problems that the supporting rigidity is insufficient and cannot be adjusted, the foundation pit is too large in deformation or the shear strength of cement soil cannot meet the requirement, and has the advantages of convenience in construction, low manufacturing cost, reliable pile forming quality, no influence of soil compaction and the like.
The purpose of the invention is realized as follows:
an I-shaped precast pile supporting structure with adjustable inserted rigidity in a cement soil wall comprises a cement soil wall 1 for water stopping and an I-shaped precast pile 2 with adjustable rigidity for soil retaining, which is arranged in the cement soil wall 1; the top end of the rigidity-adjustable I-shaped precast pile 2 is provided with a concrete crown beam 3;
the ratio of the short edge to the long edge of the pile body of the rigidity-adjustable I-shaped precast pile 2 is 0.55-0.6; the grade of the concrete strength of the pile body of the rigidity-adjustable I-shaped precast pile is C55-C80;
two ends of the pile body of the rigidity-adjustable I-shaped precast pile 2 are respectively provided with 2 polygonal steel end plates 9 and a rectangular steel end plate 10, and two sides of a pile bottom web plate and two sides of a pile top web plate are embedded with 2 web plate two-side embedded steel plates 8;
a plurality of tensionable prestressed steel strands 5 and pile body longitudinal steel bars 7 are embedded in the pile body of the rigidity-adjustable I-shaped precast pile 2; all prestressed steel strands 5 are fixed on a pile bottom end plate of the I-shaped precast pile at the bottom end of the pile body through an anchorage device, wherein 75% of the steel strands are anchored on a pile head end plate at the top end of the pile body through a steel strand anchorage device 6, 25% of the steel strands are reserved, and the reserved steel strands are tensioned according to the horizontal displacement condition of a deep soil body of a foundation pit of an engineering site in the later stage to compensate the prestress loss and further increase or adjust the rigidity of the I-shaped precast pile;
4 prestressed steel strand sleeves 4 are arranged on the pile body of the rigidity-adjustable I-shaped precast pile, and the reserved steel strands are penetrated into the prestressed steel strand sleeves 4 according to design calculation requirements before construction;
the rigidity-adjustable I-shaped precast piles 2 are inserted into the cement soil wall 1 at intervals; the net distance of the rigidity-adjustable I-shaped precast pile 2 is 20-35 cm; the short edge of the pile body of the rigidity-adjustable I-shaped precast pile is parallel to the cement soil wall, and the long edge of the pile body is 0.7-0.8 times of the thickness of the cement soil wall;
the perpendicularity of the rigidity-adjustable I-shaped precast pile inserted into the cement soil wall is consistent with the construction perpendicularity of the cement soil wall and is not more than 1/300;
wall of cement soil wall 1The deviation of the bit is not more than +20mm to-50 mm (the deviation to the pit is positive), the deviation of the wall depth is less than 50mm, the wall thickness is not less than the designed wall thickness, and the deviation is controlled to be 0 to-20 mm (the size deviation of a cutter head of the cutting box is controlled); the standard value of 28d slurry test block unconfined compressive strength of the cement soil wall is not less than 1.0MPa, the standard value of the unconfined compressive strength of 28d drilling coring is not less than 0.8MPa, and the permeability coefficient of the wall body is not more than 10 -7 cm/s; in the supporting structure for inserting the rigidity-adjustable I-shaped precast pile into the cement-soil wall, the wall end of the cement-soil wall is 1.5-2.5 m deeper than the end of the rigidity-adjustable I-shaped precast pile;
the thickness of the cement soil wall 1 is 450 mm-850 mm; when the wall thickness is not more than 550mm, the maximum construction depth is not more than 25m; when the wall thickness is not more than 700m, the maximum construction depth is not more than 40m; when the wall thickness is not more than 850mm, the maximum construction depth is not more than 55m; after the I-shaped precast pile is constructed in site to form a pile, a concrete crown beam 3 is arranged at the pile top, and the height of the concrete crown beam 3 is less than 5cm of 4 prestressed steel strand sleeves arranged at the upper end of the pile body; after the construction of arranging the concrete crown beam on the pile top is completed and the design strength is reached, the reserved steel stranded wires are tensioned hole by hole and root by root according to the change condition of the horizontal displacement of the deep layer of the soil body in the excavation process of the foundation pit on site, and the rigidity of the I-shaped precast pile is increased or adjusted.
A construction method of an I-shaped precast pile supporting structure with adjustable insertion rigidity in a cement soil wall comprises the following specific steps:
step 1: leveling a construction site, and performing cutting and stirring of a cement soil wall to form a wall;
step 2: selecting a type of an I-shaped precast pile with adjustable rigidity, manufacturing in a factory, primarily applying prestress, and fixing a part of prestress steel strands 5 through an end plate steel strand anchorage 6;
and step 3: arranging a rigidity-adjustable I-shaped precast pile inserting guide frame and a hoisting crane in place;
and 4, step 4: before the cement soil is initially set, inserting the rigidity-adjustable I-shaped precast pile into the cement soil wall 1, and meanwhile, performing perpendicularity correction by adopting a theodolite according to design requirements;
and 5: after the construction of the rigidity-adjustable I-shaped precast pile is finished, constructing a concrete crown beam 3 on the pile top according to design requirements, and reserving a pre-stressed steel strand penetrating hole on the concrete crown beam;
step 6: excavating a foundation pit, arranging an inner support according to design requirements, monitoring the deformation condition of the foundation pit by adopting a soil deep level inclinometer, monitoring the stress of a pile body by using a stress meter, and when the deformation is overlarge and reaches a design early warning value, stretching a prestressed steel strand at the top of a concrete crown beam 3 beam to increase or adjust the rigidity of the I-shaped precast pile and controlling the further development of the deformation of the foundation pit;
and 7: continuously monitoring deformation, not disconnecting the excavation foundation pit until the foundation pit is excavated to the bottom, and constructing a foundation slab of the main structure; and constructing the main structure according to design requirements.
Has the positive and beneficial effects that: the cement soil wall has wide application range, good tunneling performance on hard strata (hard soil, sand gravel, soft rock and the like) and high wall forming precision. During wall-forming tunneling and stirring, the wall quality can be monitored while drilling in the whole construction process through a parameter instrument; the dispersion is small, the strength is high, the upper and lower strength is uniform, and the water-resisting performance is good; compared with the traditional process, the cement soil mixing wall formed by channel cutting has higher strength, better smoothness, continuity, compactness and uniformity, deeper depth and better soil layer adaptability; the wall is formed continuously, seams are few, the wall is equal in thickness, the interval of the H-shaped precast piles with adjustable rigidity can be adjusted according to design requirements, and the pile position is not limited; noise and vibration are small, and the minimum distance from an adjacent building (structure) to a wall core is only 1000 mm. The supporting structure is simple to operate, convenient, rapid and reliable to construct, and simultaneously gives full play to the characteristics that the rigidity-adjustable I-shaped precast pile has high concrete strength grade and the prestress can be adjusted on site, so that the purposes of shortening the construction period and reducing the construction cost are achieved, the using amount of concrete and steel can be reduced, and the safety requirement can be met.
Drawings
FIG. 1 is a schematic cross-sectional view of a support structure according to the present invention;
figure 2 is a schematic plan view of the support structure of the present invention;
fig. 3 is a longitudinal section schematic view of a pile body of the rigidity-adjustable I-shaped precast pile in the invention;
FIG. 4 is a schematic cross-sectional view of a pile body of the stiffness-adjustable I-shaped precast pile in the invention;
FIG. 5 is a schematic top view structure diagram of the stiffness-adjustable I-shaped precast pile end plate in the invention;
FIG. 6 is a construction flow chart of a supporting structure of an I-shaped precast pile with adjustable inserted rigidity in a cement-soil wall;
in the figure, the following steps are carried out: the concrete wall comprises a cement-soil wall 1, an adjustable-rigidity I-shaped precast pile 2, a concrete crown beam 3, a prestressed steel strand sleeve 4, prestressed steel strands 5, a steel strand anchorage 6, pile body longitudinal steel bars 7, pre-embedded steel plates 8 on two sides of a web plate, polygonal steel end plates 9 and rectangular steel end plates 10.
Detailed Description
In order to make the technical means, inventive features, achievement objects and effects of the present invention easy to understand, the present invention is further explained below with reference to the accompanying drawings.
As shown in fig. 1 and fig. 6, a rigidity-adjustable i-shaped precast pile supporting structure inserted in a cement soil wall comprises a cement soil wall 1 for stopping water and a rigidity-adjustable i-shaped precast pile 2 arranged in the cement soil wall 1 for retaining soil; the top end of the rigidity-adjustable I-shaped precast pile 2 is provided with a concrete crown beam 3;
the ratio of the short edge to the long edge of the pile body of the rigidity-adjustable I-shaped precast pile 2 is 0.55-0.6; the grade of the concrete strength of the pile body of the rigidity-adjustable I-shaped precast pile is C55-C80;
as shown in fig. 3, 4 and 5, two ends of the pile body of the rigidity-adjustable i-shaped precast pile 2 are respectively provided with 2 polygonal steel end plates 9 and one rectangular steel end plate 10, and two sides of the pile bottom and the pile top web are embedded with 2 web two-side embedded steel plates 8;
as shown in fig. 2, a plurality of tensionable prestressed steel strands 5 and pile body longitudinal steel bars 7 are embedded in the pile body of the rigidity-adjustable i-shaped precast pile 2; all prestressed steel strands 5 are fixed on a pile bottom end plate of the I-shaped precast pile at the bottom end of the pile body through an anchorage device, wherein 75% of the steel strands are anchored on a pile head end plate at the top end of the pile body through a steel strand anchorage device 6, 25% of the steel strands are reserved, and the reserved steel strands are tensioned according to the horizontal displacement condition of a deep soil body of a foundation pit of an engineering site in the later period, so that the prestress loss is compensated, and the rigidity of the I-shaped precast pile is further increased or adjusted;
4 prestressed steel strand sleeves 4 are arranged on the pile body of the rigidity-adjustable I-shaped precast pile, and the reserved steel strands are penetrated into the prestressed steel strand sleeves 4 according to design calculation requirements before construction;
the rigidity-adjustable I-shaped precast piles 2 are inserted into the cement soil wall 1 at intervals; the net distance of the rigidity-adjustable I-shaped precast pile 2 is 20-35 cm; the short edge of the pile body of the rigidity-adjustable I-shaped precast pile is parallel to the cement soil wall, and the long edge of the pile body is 0.7-0.8 times of the thickness of the cement soil wall;
the perpendicularity of the rigidity-adjustable I-shaped precast pile inserted into the cement soil wall is consistent with the construction perpendicularity of the cement soil wall and is not more than 1/300;
the deviation of the wall position of the cement soil wall 1 is not more than +20mm to-50 mm (the deviation to the pit is positive), the deviation of the wall depth is less than 50mm, the wall thickness is not less than the designed wall thickness, and the deviation is controlled to be 0 to-20 mm (the size deviation of a cutter head of a cutting box is controlled); the standard value of 28d slurry test block unconfined compressive strength of the cement soil wall is not less than 1.0MPa, the standard value of the unconfined compressive strength of 28d drilling coring is not less than 0.8MPa, and the permeability coefficient of the wall body is not more than 10 -7 cm/s; in the supporting structure of the stiffness-adjustable I-shaped precast pile inserted in the cement soil wall, the wall end of the cement soil wall is 1.5-2.5 m deeper than the stiffness-adjustable I-shaped precast pile end;
the thickness of the cement soil wall 1 is 450 mm-850 mm; when the wall thickness is not more than 550mm, the maximum construction depth is not more than 25m; when the wall thickness is not more than 700m, the maximum construction depth is not more than 40m; when the wall thickness is not more than 850mm, the maximum construction depth is not more than 55m; after the I-shaped precast pile is constructed in site to form a pile, a concrete crown beam 3 is arranged at the pile top, and the height of the concrete crown beam 3 is less than 5cm of 4 prestressed steel strand sleeves arranged at the upper end of the pile body; after the construction of arranging the concrete crown beam on the pile top is completed and the design strength is reached, the reserved steel stranded wires are tensioned hole by hole and root by root according to the change condition of the horizontal displacement of the deep layer of the soil body in the excavation process of the foundation pit on site, and the rigidity of the I-shaped precast pile is increased or adjusted.
A construction method for a supporting structure of an I-shaped precast pile with adjustable inserted rigidity in a cement-soil wall comprises the following specific steps:
step 1: leveling a construction site, and performing cutting and stirring of a cement soil wall to form a wall;
step 2: the rigidity-adjustable I-shaped precast pile is subjected to shape selection, factory manufacturing and preliminary prestress application, and a part of prestress steel strands 5 are fixed through an end plate steel strand anchorage device 6;
and step 3: arranging a rigidity-adjustable I-shaped precast pile inserting guide frame and a hoisting crane in place;
and 4, step 4: before the cement soil is initially set, inserting the rigidity-adjustable I-shaped precast pile into the cement soil wall 1, and meanwhile, performing perpendicularity correction by adopting a theodolite according to design requirements;
and 5: after the construction of the rigidity-adjustable I-shaped precast pile is finished, constructing a concrete crown beam 3 on the pile top according to design requirements, and reserving a pre-stressed steel strand penetrating hole on the concrete crown beam;
step 6: excavating a foundation pit, arranging an inner support according to design requirements, monitoring the deformation condition of the foundation pit by adopting a soil deep level inclinometer, monitoring the stress of a pile body by using a stress meter, and when the deformation is overlarge and reaches a design early warning value, stretching a prestressed steel strand at the top of a concrete crown beam 3 beam to increase or adjust the rigidity of the I-shaped precast pile and controlling the further development of the deformation of the foundation pit;
and 7: continuously monitoring deformation, not disconnecting the excavation foundation pit until the foundation pit is excavated to the bottom, and constructing a foundation slab of the main structure; and constructing the main structure according to design requirements.
As shown in the attached drawings 1 to 6, the supporting structure for inserting the stiffness-adjustable I-shaped precast pile into the cement-soil wall comprises five processes of inserting and anchoring the stiffness-adjustable I-shaped precast pile steel strand, stirring the cement-soil wall into a wall, inserting the stiffness-adjustable I-shaped precast pile into the cement-soil wall, constructing a concrete crown beam, and tensioning a prestressed steel strand according to horizontal displacement of a soil body in the later stage.
The rigidity-adjustable I-shaped precast pile is provided with a plurality of prestressed steel strands 5 and pile body longitudinal steel bars 7, the prestressed steel strands are 15.2 non-bonding types, the number of the prestressed steel strands is determined according to design calculation, the pile end of the rigidity-adjustable I-shaped precast pile is provided with 2 polygonal steel end plates 9 and 1 rectangular steel end plate 10, before the I-shaped precast pile is inserted into a cement soil wall, all the prestressed steel strands 5 are fixed on a pile bottom end plate through a steel strand anchorage device 6, and a pile top anchorage device only fixes 75% of the prestressed steel strands. The adjustable i-shaped precast pile web both sides of rigidity set up 2 belly both sides pre-buried steel sheets 8 respectively, and polygon end steel plate 9 and rectangle end steel plate 10 are used for adjustable i-shaped precast pile of rigidity to connect the stake welding with web both sides pre-buried steel sheet 8 and use, and the pre-buried steel sheet in web both sides plays two sections stake welding back pile web side reinforcing effect. The rigidity-adjustable I-shaped precast pile is processed in a factory, the section size, the length and the concrete strength grade of a pile body are determined according to design calculation requirements, and the rigidity-adjustable I-shaped pile is transported to a construction site after being manufactured.
During construction, firstly, grooving and cutting a soil body and stirring to form a cement-soil wall (1), then welding and connecting a plurality of sections of I-shaped precast piles with adjustable rigidity into a whole through polygonal steel end plates 9 and rectangular steel end plates 10 according to the designed length and size, meanwhile, reinforcing and connecting through embedded steel plates 8 on two sides of a pile web plate, finally, hoisting and inserting the I-shaped precast piles with adjustable rigidity into the cement-soil wall by utilizing a crawler crane, and determining the implantation depth according to engineering requirements.
And moving the construction equipment to a second position where the stiffness-adjustable I-shaped precast pile needs to be inserted into the cement-soil wall, and implementing the same operation.
After the rigidity-adjustable I-shaped precast pile is inserted into a cement soil wall, a pre-reserved prestress steel strand sleeve 4 of 25% prestress steel strands is arranged before a concrete crown beam is constructed; the prestressed steel strand sleeve 4 is a scaffold steel pipe with the diameter of 48mm and the wall thickness of 3 mm. The prestressed steel strand sleeve 4 is connected with the polygonal steel end plate 9 of the stiffness-adjustable I-shaped pile through welding, the height of the prestressed steel strand sleeve 4 is larger than that of the concrete crown beam by 5cm, and no concrete is filled in the steel sleeve when the concrete of the crown beam is poured and vibrated.
And excavating the deep foundation pit after the maintenance strength of the concrete crown beam reaches the design requirement after the construction is finished. During the excavation of the foundation pit and the construction of the basement, the horizontal displacement of the deep soil body on the outer side of the foundation pit is monitored in the whole process, and the reserved 25% of unstretched prestressed steel strands are tensioned according to the displacement of the soil body to perform rigidity adjustment, so that the aim of increasing or adjusting the rigidity of the pile body of the I-shaped precast pile and further resisting the deformation of the soil body is fulfilled.
And after the steel strand is tensioned, the steel strand is fixed on the top of the concrete crown beam 3 through an anchorage device.
The cement soil wall has wide application range, good tunneling performance on hard strata (hard soil, sand gravel, soft rock and the like) and high wall forming precision. During wall-forming tunneling and stirring, the wall quality can be monitored while drilling in the whole construction process through the parameter instrument; the dispersion is small, the strength is high, the upper and lower strength is uniform, and the water-resisting performance is good; compared with the traditional process, the cement soil mixing wall formed by channel cutting has higher strength, better smoothness, continuity, compactness and uniformity, deeper depth and better soil layer adaptability; the wall is formed continuously, seams are few, the wall is equal in thickness, the interval of the H-shaped precast piles with adjustable rigidity can be adjusted according to design requirements, and the pile position is not limited; noise and vibration are small, and the minimum distance from an adjacent building (structure) to a wall core is only 1000 mm. The supporting structure is simple to operate, convenient, rapid and reliable to construct, and simultaneously gives full play to the characteristics that the rigidity-adjustable I-shaped precast pile has high concrete strength grade and the prestress can be adjusted on site, so that the purposes of shortening the construction period and reducing the construction cost are achieved, the using amount of concrete and steel can be reduced, and the safety requirement can be met.
The foregoing describes the general principles, essential features, and advantages of the present invention, and is provided only as exemplary embodiments of the invention, rather than as limitations thereon, and any modifications, equivalents, and improvements made within the spirit and scope of the present invention are intended to be included within the scope of the present invention as claimed.
Claims (7)
1. The utility model provides an adjustable i-shaped precast pile supporting construction of earth cement wall interpolation rigidity which characterized in that: comprises a cement soil wall (1) for stopping water and H-shaped precast piles (2) with adjustable rigidity and arranged in the cement soil wall (1) at intervals and used for retaining soil; the top end of the rigidity-adjustable I-shaped precast pile (2) is provided with a concrete crown beam (3);
a plurality of tensionable prestressed steel strands (5) and pile body longitudinal steel bars (7) are embedded in the pile body of the rigidity-adjustable I-shaped precast pile (2); all the prestressed steel strands (5) are fixed on the pile bottom end plate of the I-shaped precast pile through anchorage devices at the bottom end of the pile body,
wherein 75% of the steel strands are anchored on the pile head end plate at the top end of the pile body through a steel strand anchorage device (6), 25% of the reserved steel strands are tensioned according to the horizontal displacement condition of a deep soil body of a foundation pit of an engineering site at the later stage, the prestress loss is compensated, and the rigidity of the I-shaped precast pile is further increased; 4 prestressed steel strands are arranged on the pile body of the rigidity-adjustable I-shaped precast pile to penetrate into the prestressed steel strand sleeve (4), and the reserved steel strands penetrate into the prestressed steel strand sleeve (4) according to design calculation requirements before construction;
the thickness of the cement soil wall (1) is 450 mm-850 mm; when the wall thickness is not more than 550mm, the maximum construction depth is not more than 25m; when the wall thickness is not more than 700m, the maximum construction depth is not more than 40m; when the wall thickness is not more than 850mm, the maximum construction depth is not more than 55m; after the I-shaped precast pile is constructed and formed in site, a concrete crown beam (3) is arranged at the pile top, and the height of the concrete crown beam (3) is 5cm less than that of 4 prestressed steel strand sleeves arranged at the upper end of a pile body; after the construction of arranging the concrete crown beam on the pile top is completed and the design strength is reached, the reserved steel strands are tensioned hole by hole and root by root according to the horizontal displacement change condition of the deep layer of the soil body in the excavation process of the foundation pit on site, and the rigidity of the I-shaped precast pile is increased.
2. The i-shaped precast pile supporting structure with adjustable insertion rigidity in cement-soil wall according to claim 1, characterized in that: the ratio of the short edge to the long edge of the pile body of the rigidity-adjustable I-shaped precast pile (2) is 0.55-0.6; the grade of the strength of the concrete of the pile body of the rigidity-adjustable I-shaped precast pile is C55-C80.
3. The i-shaped precast pile supporting structure with adjustable insertion rigidity in cement-soil wall according to claim 1, characterized in that: two ends of the pile body of the rigidity-adjustable I-shaped precast pile (2) are respectively provided with 2 polygonal steel end plates (9) and a rectangular steel end plate (10), and two sides of the pile bottom and two sides of the pile top web are embedded with 2 web two-side embedded steel plates (8).
4. The i-shaped precast pile supporting structure with adjustable insertion rigidity in cement-soil wall according to claim 1, characterized in that: the rigidity-adjustable I-shaped precast piles (2) are inserted into the cement soil wall (1) at intervals; the net distance of the rigidity-adjustable I-shaped precast piles (2) is 20-35 cm; the short edge of the pile body of the rigidity-adjustable I-shaped precast pile is parallel to the cement soil wall, and the long edge of the pile body is 0.7-0.8 times of the thickness of the cement soil wall.
5. The i-shaped precast pile supporting structure with adjustable insertion rigidity in cement-soil wall according to claim 1, characterized in that: the perpendicularity of the rigidity-adjustable I-shaped precast pile inserted into the cement soil wall is consistent with the construction perpendicularity of the cement soil wall.
6. The i-shaped precast pile supporting structure with adjustable insertion rigidity in cement-soil wall according to claim 1, characterized in that: the wall position deviation of the cement soil wall (1) is not more than +20mm to-50 mm, the deviation to the pit is positive, the wall depth deviation is less than 50mm, the wall forming thickness is not less than the designed wall thickness, the deviation is controlled to be 0 to-20 mm, and the size deviation of a cutter head of a cutting box is controlled; the standard value of 28d slurry test block unconfined compressive strength of the cement soil wall is not less than 1.0MPa, the standard value of the unconfined compressive strength of 28d drilling coring is not less than 0.8MPa, and the permeability coefficient of the wall body is not more than 10 -7 cm/s; in the supporting structure for inserting the rigidity-adjustable I-shaped precast pile into the cement soil wall, the wall end of the cement soil wall is 1.5 m-2.5 m deeper than the rigidity-adjustable I-shaped precast pile end.
7. A construction method of an I-shaped precast pile supporting structure with adjustable insertion rigidity in a cement soil wall is characterized by comprising the following specific steps:
step 1: leveling a construction site, and performing cutting and stirring of a cement soil wall to form a wall;
step 2: selecting a rigidity-adjustable I-shaped precast pile, manufacturing in a factory, and primarily applying prestress, wherein a plurality of tensionable prestress steel strands (5) and pile body longitudinal steel bars (7) are embedded in a pile body of the rigidity-adjustable I-shaped precast pile (2); all the prestressed steel strands (5) are fixed on a pile bottom end plate of the I-shaped precast pile at the bottom end of the pile body through steel strand anchorage devices, wherein 75 percent of the steel strands are anchored on a pile head end plate at the top end of the pile body through steel strand anchorage devices (6), and 25 percent of the steel strands are reserved; 4 prestressed steel strands are arranged on the pile body of the rigidity-adjustable I-shaped precast pile to penetrate into the prestressed steel strand sleeve (4), and the reserved steel strands penetrate into the prestressed steel strand sleeve (4) according to design calculation requirements before construction;
and 3, step 3: arranging a rigidity-adjustable I-shaped precast pile inserting guide frame and a hoisting crane in place;
and 4, step 4: inserting the rigidity-adjustable I-shaped precast piles into the cement soil wall (1) at intervals before the cement soil is not initially set, and meanwhile, performing perpendicularity correction by adopting a theodolite according to design requirements;
and 5: after the construction of the rigidity-adjustable I-shaped precast pile is finished, constructing a concrete crown beam (3) on the pile top according to design requirements, and reserving a pre-stressed steel strand penetrating hole on the concrete crown beam;
step 6: excavating a foundation pit, arranging an inner support according to design requirements, monitoring the deformation condition of the foundation pit by adopting a soil deep level inclinometer, monitoring the stress of a pile body by using a stress meter, and when the deformation is overlarge and reaches a design early warning value, tensioning reserved 25% of unstretched prestressed steel strands at the beam top of the concrete crown beam (3), increasing the rigidity of the I-shaped precast pile and controlling the further development of the deformation of the foundation pit;
and 7: continuously monitoring deformation, not disconnecting the excavation foundation pit until the foundation pit is excavated to the bottom, and constructing a foundation slab of the main structure; and constructing the main structure according to design requirements.
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| CN109555145B (en) * | 2018-12-04 | 2019-10-08 | 南京工业大学 | Hot melt effect pile tip rigidity adjusting device |
| CN112482392A (en) * | 2020-11-19 | 2021-03-12 | 建研地基基础工程有限责任公司 | Integrated foundation pit supporting structure and construction method thereof |
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