CN111676969A - Foundation pit bag type enlarged footing anchor cable supporting structure and construction method - Google Patents
Foundation pit bag type enlarged footing anchor cable supporting structure and construction method Download PDFInfo
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- CN111676969A CN111676969A CN202010475955.8A CN202010475955A CN111676969A CN 111676969 A CN111676969 A CN 111676969A CN 202010475955 A CN202010475955 A CN 202010475955A CN 111676969 A CN111676969 A CN 111676969A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D5/00—Bulkheads, piles, or other structural elements specially adapted to foundation engineering
- E02D5/74—Means for anchoring structural elements or bulkheads
- E02D5/76—Anchorings for bulkheads or sections thereof in as much as specially adapted therefor
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D17/00—Excavations; Bordering of excavations; Making embankments
- E02D17/02—Foundation pits
- E02D17/04—Bordering surfacing or stiffening the sides of foundation pits
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2250/00—Production methods
- E02D2250/003—Injection of material
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2300/00—Materials
- E02D2300/0004—Synthetics
- E02D2300/0018—Cement used as binder
- E02D2300/0023—Slurry
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
- E02D2600/00—Miscellaneous
- E02D2600/30—Miscellaneous comprising anchoring details
Abstract
The invention discloses a foundation pit bag type enlarged footing anchor cable support construction method, which relates to the field of anchor cables and aims to achieve the purpose, the technical scheme of the invention comprises anchor holes, a support structure, anchor bars, reinforced cement-soil piles and an anchor device; the anchor hole is arranged in the side slope, and the surface layer of the side slope where the orifice of the anchor hole is located is provided with a retaining structure; the front end of each anchor bar extends into the anchor hole from the hole opening of the anchor hole, and an anchor plate is fixed at the front end of each anchor bar; the reinforced cement-soil pile is spirally sprayed at high pressure inside the anchor hole, the reinforced cement-soil pile is provided with an expanding head section and an expanding diameter section, the expanding head section is arranged corresponding to the anchor plate, and the expanding diameter section is arranged in the middle of the anchor hole; the anchorage device is fixed on the anchor bar, and one side of the anchorage device, which faces the anchor hole, is propped against the enclosure structure. The large-diameter cement soil pile body formed by high-pressure rotary spraying can improve the mechanical property of loose soft soil, so that the soft soil is changed into a cement soil body with higher strength, and the shear resistance of a soil body sliding surface is effectively improved.
Description
Technical Field
The invention relates to a foundation pit bag type enlarged head anchor cable supporting structure and a construction method, and mainly relates to the field of anchor cables.
Background
With the continuous and rapid promotion of the infrastructure construction in China, the engineering construction technology is different day by day. In order to provide larger space or reduce the engineering quantity of a supporting system and improve the slope stability in slope support, a deep foundation pit or slope support conventionally adopts an anchor rod and anchor cable support system. The bag type high-pressure suspension-spraying enlarged head prestressed anchor cable support of the foundation pit is an improved process of anchor cable support, over-high-pressure grouting occurs in the current construction technology, a method for constructing an enlarged section by using an enlarged head drilling tool is adopted, from the practical point of view, the reaming range of the drilling tool is relatively limited, a technology for forming the enlarged section by high-pressure water cutting reaming exists, and a large-range hole collapse easily occurs in weak geology.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a foundation pit bag type expanded head anchor cable supporting structure and a construction method, wherein a large-diameter cemented soil pile body formed by high-pressure rotary spraying can be used for firstly improving the mechanical property of loose soft soil, so that the soft soil is changed into a cemented soil body with higher strength, and the shearing resistance of a soil body sliding surface is effectively improved; secondly, the large-diameter and variable-diameter cement soil pile body has larger contact area with the soil layer, so that larger frictional resistance is generated between the pile body and the soil layer, and the anchoring force of the supporting structure can be ensured to meet the design requirement.
In order to achieve the purpose, the technical scheme of the invention is as follows: the anchor hole, the enclosure structure, the anchor bar, the reinforced cement-soil pile and the anchorage device are included; the anchor hole is arranged in the side slope, and a retaining structure is arranged on the surface layer of the side slope where the orifice of the anchor hole is located; the front end of each anchor bar extends to the inside of the anchor hole from the hole opening of the anchor hole, and an anchor plate is fixed at the front end of each anchor bar; a reinforced cement-soil pile is jet-sprayed at high pressure in the anchor hole, the reinforced cement-soil pile is provided with an expanding head section and an expanding diameter section, the expanding head section is arranged corresponding to the anchor plate, and the expanding diameter section is arranged in the middle of the anchor hole; the anchor device is fixed on the anchor bar, and the anchor device is abutted to the envelope structure towards one side of the anchor hole.
Preferably, the method comprises the following steps: 1) proportioning cement slurry; 2) forming holes and reaming the rotary jet grouting pile;
3) manufacturing anchor bars; 4) laying an anchor cable; 5) grouting construction; 6) hanging a net on the slope surface, and performing spray anchor construction; 7) manufacturing and installing a prestressed base; 8) tensioning anchor bars; 9) locking the anchor bars; 10) and (5) monitoring the foundation pit.
Preferably, the cement slurry ratio comprises: the cement mixing amount is generally 20-30%, the water cement ratio is generally 0.7-1.0, and the cement slurry is 42.5 grade ordinary portland cement paste.
Preferably, the hole forming and reaming construction of the jet grouting pile is as follows: adopting a jumbolter, wherein a high-pressure rotary drill bit and a flank nozzle of the jumbolter are gradually and automatically pushed under the driving of power in the drilling process until the designed depth and diameter are reached; and (3) reaming process: the high-pressure rotary drill bit rotates uniformly, sinks in a uniformly lifting mode, and performs high-pressure injection expansion from top to bottom or from bottom to top.
Preferably, the reaming process uses water or cement slurry; when the cement slurry reaming process is adopted: reaming twice up and down; when a clear water reaming process is adopted: and reaming again by adopting cement slurry after reaming by clear water.
Preferably, the anchor line of the jet grouting pile is placed: and (4) arranging steel strands in the anchor pile, sleeving a drill bit into the anchor pile, entering the bottom of the jet grouting pile, and leaving 1.0m of single steel strand outside.
Preferably, the grouting construction of the jet grouting pile comprises the following steps: the distance from the grout outlet of the grouting pipe to the bottom of the hole is not more than 300mm, grout should be continuously poured from bottom to top, and smooth water and air drainage from the hole should be ensured.
Preferably, the anchor bar is tensioned: the slope anchor cable is tensioned and locked by a high-pressure oil pump and a piercing jack.
Preferably, the anchor head is pretensioned once by using a 20% locking load before formal tensioning, then tensioned in stages by using 50% and 100% locking loads, then overstretched to 100% locking loads, kept for 5 minutes under the overstretched loads, and then locked according to the locking loads after no displacement phenomenon of the anchor head is observed.
Preferably, in: the bearing surface of the anchor bar tensioning anchor inclined supporting pedestal is smooth and vertical to the axis direction of the anchor bar, the anchor device is installed to be closely attached and centered with the anchor backing plate and the jack, the axis of the jack is in a straight line with the anchor hole and the axis of the anchor bar, and the anchor head is prevented from being bent or deflected, so that the uniform and coaxial bearing is ensured.
The technical principle and the beneficial effects of the invention are as follows:
the large-diameter cement soil pile body formed by high-pressure rotary spraying can improve the mechanical property of loose soft soil, so that the soft soil is changed into a cement soil body with higher strength, and the shear resistance of a soil body sliding surface is effectively improved; secondly, the large-diameter and variable-diameter cement soil pile body has larger contact area with the soil layer, so that larger frictional resistance is generated between the pile body and the soil layer, and the anchoring force of the supporting structure can be ensured to meet the design requirement.
The expanded head is very beneficial to improving the stress in an anchoring system, and the shear surface of a soil layer is dispersed, so that the bearing capacity is improved by 2-3 times. The high-pressure rotary spraying cement reinforced pile obviously helps to improve the shear resistance of the sliding surface.
The expansion section can improve the jet grouting pressure during construction, and is formed by pre-stirring, cutting by a water jet cutter to destroy the hole expansion of a soil layer at the end part and then jet grouting.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the description of the embodiments will be briefly introduced below, it is obvious that the drawings in the following description are only one of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.
Fig. 1 is a schematic structural diagram of an embodiment of the present invention.
The anchor comprises anchor bars 1, reinforced cement soil piles 2, an enlarged head section 3, an anchor plate 4, an anchor device 5, a building envelope 6, an enlarged diameter section 7 and an imaginary sliding plane 8.
Detailed Description
The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are merely preferred embodiments of the present invention, rather than all 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.
Examples
As shown in fig. 1, the embodiment of the invention comprises anchor holes, a building envelope 6, anchor bars 1, reinforced cement-soil piles 2 and anchors 5; the anchor hole is arranged in the side slope, and the surface layer of the side slope, where the orifice of the anchor hole is located, is provided with an enclosure structure 6; the front end of the anchor bar 1 extends to the inside of the anchor hole from the orifice of the anchor hole, and an anchor plate 4 is fixed at the front end of the anchor bar 1; a reinforced cement-soil pile 2 is jet-sprayed at high pressure in the anchor hole, the reinforced cement-soil pile 2 is provided with an expanding head section 3 and an expanding diameter section 7, the expanding head section 3 is arranged corresponding to the anchor plate 4, and the expanding diameter section 7 is arranged in the middle of the anchor hole; the anchorage device 5 is fixed on the anchor bar 1, and the anchorage device 5 is abutted to the envelope structure 6 towards one side of the anchor hole.
1 preparation for construction
(1) Before the high-pressure jet grouting stiffening cement soil pile anchor construction, the design content, the design requirement, the stratum condition and the environmental condition should be studied in detail;
(2) and further checking the underground buried objects and the barriers considered in the design stage, further determining the positions, shapes, sizes and numbers of the underground buried objects and the barriers, and simultaneously providing measures such as elimination and protection treatment.
(3) And (4) mastering the surrounding conditions of the engineering, the building state and the influence of the building state, predicting possible problems and providing corresponding countermeasures.
(4) Carefully checking the model, variety and specification of raw materials and various instruments and equipment, and checking whether the main performance of the raw materials and the instruments and equipment meets the design requirements.
(5) For special or particularly important geological conditions, drilling, pile forming, tensioning and locking tests are preferably carried out before formal construction, so that construction process parameters with high pertinence are obtained, and the adaptability of a construction process and construction equipment is checked.
2-bag type rotary-spraying expanded anchor cable design
2.1 Anchor design computation content
The anchor cable with the enlarged head comprises two parts: anchor cable and high-pressure rotary-spraying cement-soil pile. The front end of the anchor cable drill rod is provided with a detachable drill bit, and the drill bit can bring the drill bit of the anchor cable into the designed soil depth while the drill bit is in Jq-TL in the soil. After the drilling is completed, the flexible drill bit at the front end is detached, liquid slurry is sprayed and injected into the surrounding hole wall in a high-pressure rotary mode through the hollow channel of the drill rod, the surrounding soil body is cut by a high-pressure jet flow generated by a high-pressure liquid slurry pump, slurry in the soil body is replaced by the cement slurry, the cement slurry is compressed by a modulation device, and the gourd-shaped anchor body expanded head anchor cable is formed from bottom to top, so that the pulling resistance is greatly improved under the condition of the same length: firstly, the cross section area of the enlarged head anchor cable is increased, so that the friction force between the enlarged head anchor cable and the surrounding soil body is increased; and secondly, the front-section end of the anchor cable with the enlarged head and the soil body are mutually extruded to form an end bearing force. The drawing shows that the pulling resistance T can be composed of three parts: t1, T2, T3.
T-T1 + T2+ T3; in the formula: t1 friction between the ordinary anchoring section and the soil: t2 expanding the friction between the anchor section and the earth; one end of the T3 bears force.
T1 ═ dLdtf; in the formula: d a borehole diameter; ld is the length of a common anchor segment; tf is the frictional resistance between the walls of the holes.
T2 ═ DLDtfD; in the formula: d, expanding the diameter of the head; LD-enlarged head length; tfD A side friction of the enlarged head in view of high pressure injection control.
T3: tr/4 (D2-D2) PD formula: the PD soil body acts on the positive pressure of the expanding head.
2.2 Anchor rope support System design
(1) The diameter and the interval of the jet-grouting mixing pile are adopted for supporting and reinforcing the slope, the diameter of the enlarged head of the jet-grouting mixing pile, the specification and the number of the steel strands, the inclination angle, the strength and the thickness of the sprayed concrete are adopted.
(2) And taking the outer side line of the foundation slab as a foundation, and outwards expanding 1.0m to serve as the lower side line of the foundation pit excavation support. And dividing the supporting structure into a plurality of side surfaces for calculation respectively according to the surrounding site and the foundation excavation elevation. And performing comparative analysis and calculation by using two kinds of software, and determining a final design scheme by combining construction tests in similar stratums.
(3) The cement-soil pile body with large diameter and the reinforced cement-soil pile body are formed by utilizing jet grouting, stirring, cutting, permeating, extruding and replacing, so that the bending strength and the shearing strength of the cement-soil are greatly improved, and the effect of reinforcing the support is achieved. The bending resistance and the shearing resistance of the cement soil are improved to a certain extent by utilizing the anchor plate and pretension.
(4) By combining the anchor plate, the anchor bars and the cement soil, higher anchoring force is generated on a weaker soil layer, and deformation of the soil body slope can be effectively restrained.
2.3 Cement grout proportioning
(1) The grouting material is generally 42.5-grade ordinary portland cement paste, and additives can be added if special requirements exist.
(2) The cement mixing amount is generally 20-30%, the water cement ratio is generally selected from 0.7-1.0, if the stratum condition is special, a slurry proportioning test needs to be carried out on site, and the pile forming quality of the high-pressure jet grouting stiffening cement soil pile is ensured.
(3) The cement paste is mixed uniformly and used along with the mixing, and the anchor cable installation work is finished before initial setting of the cement paste which is mixed at one time.
3, rotary spraying pile hole forming and reaming construction: the hole site is determined by a level gauge and a steel ruler according to the elevation and the horizontal distance of the design requirement, the marking is made, a special anchor rod drilling machine is adopted, the hole site is aligned, the angle is adjusted, the high-pressure rotary drill bit and the flank nozzle are gradually and automatically pushed under the power pushing, until the design depth and the diameter are reached, the high-pressure rotary drill bit uniformly rotates, the uniform lifting type sinks, the high-pressure injection expansion is carried out from top to bottom or from bottom to top, and the drilling, the reaming depth and the diameter of the anchor rod meet the design requirement.
The cement for high-pressure injection grouting is preferably ordinary Portland cement with the strength not lower than 42.5. The length of the high-pressure pipe for connecting the high-pressure grouting pump and the drilling machine and conveying high-pressure jet liquid is not more than 50 m. When the nozzle reaches the position of the designed enlarged head, high-pressure jet reaming can be carried out according to the process parameters specified by the design. The drill bit should be rotated, lifted or lowered uniformly, and the high pressure jet reaming is performed from top to bottom or from bottom to top. The high pressure jet reaming can be performed by water or cement slurry. When the cement slurry reaming process is adopted, reaming is carried out at least twice up and down and back and forth; when the clear water reaming process is adopted, the cement slurry is finally adopted for reaming once.
4, anchor bar manufacturing: and (4) manufacturing the anchor bar body, and performing appearance inspection and inspection of each part of the anchor bar body. The anchor bar of the anchor cable adopts a phi s15.2 steel strand (strength grade 1860Mpa) with high strength and low looseness, and the anchor bar is subjected to oil and rust removal treatment, has no oil stain and rust spots, is straight and intact, and has no dead bend, hard bending or severe collision and cutting damage. The arrangement and distribution of the anchor bar strands and the binding frame meet the design requirements, the bar strands are straight, do not twist or cross, do not stick to each other, are arranged uniformly, and the binding frame is firm. The anchor bar free section antirust paint, the anticorrosive oil and various winding sealing measures meet the design requirements, and the antirust paint is uniformly brushed without black bottom; the anti-corrosion oil completely covers and fills the space between the anchor bar material and the outer ring layer; the winding sealing is firm and tight. The anchor bar free section plastic sleeve, the grouting sleeve, the isolation (centering) bracket, the tightening hoop and the guide sharp shell binding frame meet the design requirements, the plastic sleeve is stably bound and tightly plugged, the strength is sufficient, the appearance is intact, and no damage repairing trace exists; the grouting pipe is correctly arranged, and is uniformly bundled and appropriately tightened; the isolation (centering) bracket, the tightening ring and the guide tip shell are uniformly distributed, accurately positioned and firmly and stably bound. And the anchor bars are numbered and listed according to the length and specification of the anchor bar body, and need to be approved by a field supervision engineer before use.
5, placing an anchor cable of the jet grouting pile: after the high-pressure jet grouting enlarged head anchor rod is subjected to reaming, the anchor rod body is brought into the anchor hole to the designed depth. The anchor pile is internally provided with steel strands, the nominal diameter of each steel strand is phi 12.7mm, the end of each steel strand adopts a phi 150 multiplied by 20 steel plate anchor disc, the steel strands are sleeved into a drill bit and enter the bottom of the jet grouting pile, and 1.0m of each steel strand is reserved outside the steel strand for tensioning.
Before the anchor bar body is installed in the anchor hole, the manufacturing quality of the anchor bar body is checked to ensure that the assembly of the anchor bar body meets the design requirements, and the anchor bar body is approved by a field supervision engineer. The sundries in and around the anchor hole are required to be cleaned. The length of the anchor bar body is consistent with the designed anchor hole depth, the anchor bar body has no obvious bending and twisting phenomena, the anchor bar protective medium has no damage, and the damaged anchor bar body needs to be repaired. When the anchor rib body is placed in the inlet hole, the anchor rib body is prevented from being extruded, bent or twisted, the inclination angle and the direction of the inlet hole of the anchor rib body are consistent with those of the anchor hole, smooth pushing is required, shaking, twisting and moving are strictly prohibited, and beam scattering and blocking in the midway are prevented. The length of the anchor rib body inlet hole is required to meet the design requirement, and after the anchor rib body is installed, the anchor rib body cannot be knocked randomly and cannot suspend a heavy object.
6, grouting construction of the jet grouting pile: and the high-pressure grouting pipe is arranged to the bottom of the hole along with the anchor cable, and after the sleeve is removed, the rotary jet reaming is started, and the grouting pressure is 25-30 Mpa. The downward inclined anchor rod is used for grouting, the distance from a grout outlet of a grouting pipe to the bottom of a hole is not more than 300mm, grout is continuously poured from bottom to top, and smooth water and air drainage from the hole is ensured. The slurry production capacity of the grouting equipment can meet the planned requirement, the rated pressure can meet the grouting requirement, and the adopted grouting pipe can complete continuous grouting of a single anchor rod within 1 h. The grouting slurry should be stirred uniformly, used as it is, and used up before initial setting. When the grout overflows from the orifice or the grout discharged by the exhaust pipe is consistent with the injected grout in color and concentration, the grouting can be stopped. The compression strength of the slurry of the anchoring section is not less than 20Mpa, the number of test blocks for slurry strength test is less than 30, and if the number of anchor rods constructed in a single day is less than 30, the total number of 30 anchor rods is not less than one group; if the number of the anchor rods constructed in a single day exceeds 30, the number of the anchor rods constructed in the single day is not less than one. The number of test blocks should not be less than 6.
7, hanging a net on a slope surface, and performing spray anchor construction: binding reinforcing steel bar net sheets according to meshes of 200 multiplied by 200, carrying out phi 8@200 multiplied by 200 bidirectional binding, and arranging two channels of 2 phi 16 reinforcing steel bars in the horizontal direction of an anchor head to be welded with a steel plate in a full-length mode. Spraying C20 fine stone concrete with the thickness of 120mm, and the mixing ratio is as follows: cement: medium sand: the crushed stone is 1:2: 2.5.
8, manufacturing and installing a prestressed base: the prestressed base is made of reinforced concrete or section steel. When the prestressed base is manufactured and installed, a horizontal groove is cut on the enclosure structure pile body in a certain range above and below the horizontal position of the high-pressure jet grouting reinforced cement soil pile anchor, the depth and the width of the cut groove meet the size requirements of the prestressed base, and the prestressed base can be placed in the groove.
The prestressed base is a direct stressed component when the anchor bar body is tensioned, so the stressed surface of the prestressed base is smooth and reliable and is vertical to the axial direction of the anchor bar body.
9, tensioning anchor bars: and tensioning and locking the anchor bars should be carried out after the construction of the high-pressure jet grouting stiffening cement soil pile is finished and the maintenance is carried out to the designed strength. The slope anchor cable is tensioned and locked by a high-pressure oil pump and a piercing jack. And (3) pre-tensioning once by using 20% of locking load before formal tensioning, then tensioning in stages by using 50% and 100% of locking load, then supertensioning to 100% of locking load, keeping for 5 minutes under the supertensioning load, observing that the anchor head has no displacement phenomenon, and then locking according to the locking load. The bearing surface of the anchor bar tensioning anchor inclined supporting pedestal is smooth and is vertical to the axis direction of the anchor bar. The anchor device is installed to be closely attached and centered with the anchor backing plate and the jack, the axis of the jack is in the same line with the axis of the anchor hole and the axis of the anchor rib body, the anchor head is not required to be bent or deflected, the uniform and coaxial bearing is ensured, and the requirement of adjustment by a steel gasket is met if necessary. When the strength of the anchoring body and the concrete of the pedestal reach more than 80% of the designed strength, tensioning can be carried out. (if the test is performed after the test is finished under the condition that the designed strength is achieved for testing the anchor holes), the anchor bars are tensioned according to a certain program, and the mutual influence of the adjacent anchor holes is considered in the anchor bar tensioning sequence.
Before formal tensioning of the anchor bar, pre-tensioning is carried out on the anchor bar for 1-2 times by taking 0.1-0.2 times of design tension value, so that all parts of the anchoring body are in contact and close contact, and the anchor bar body is flat and straight along the cloth. The tension control stress of the permanent anchor bar should not exceed 0.6 times of the limit stress value, and the tension control stress of the temporary anchor bar should not exceed 0.65 times of the limit stress value.
The stretching of the anchor bars in the slope anchoring engineering is preferably ultra-stretching, and the ultra-stretching force value is 1.1 to 1.2 times of the designed tension value. The tension value of the anchor bar is applied by two times of tensioning operation, the first tensioning operation value is half of the designed tension value, and the second tensioning operation is carried out until the tension value is over. And each tensioning is preferably divided into 5-6 levels, except for 30 minutes for the first tensioning, the remaining load-holding stabilization time of each level is 5 minutes, and the elongation of the anchor tendon body corresponding to each level of load is recorded and recorded. And (3) uniformly stressing the anchor bar body during tensioning, finding out the reason to be analyzed under abnormal conditions, and timely processing and solving the problem. If the cable is a pressure dispersion type prestressed anchor cable or a load dispersion type prestressed anchor cable, the unit anchor cables are respectively tensioned according to design tensioning requirements, and after the elastic extension difference of the unit anchor cables caused by different free section lengths under the same load condition is compensated, the unit anchor cables are simultaneously tensioned.
The stretching principle of the anchor bars on the same structural unit is required to be synchronously carried out, so that the uniform stress of the structure is ensured, and the local change and the mutual influence are avoided. If the construction equipment and the structural conditions are limited, the two tensioning operations are combined, and the circular tensioning is carried out according to the stress characteristics and rules of the structural units and a reasonable mode. If the circular tensioning is adopted, during the first tensioning operation, the operation principle of firstly stretching left and right and then middle, firstly stretching up and down and then middle, and firstly diagonal and then middle is adopted, the tensioning scheme is reasonably drawn up by combining the stress characteristics of the specific structural unit and the arrangement condition of the anchor holes, and the construction can be operated after the design and supervision department is informed to check and approve. And (4) performing second tensioning operation, namely circularly tensioning operation according to the sequence of the first tensioning operation until tensioning meets the set maximum tensioning load value.
10, locking anchor bars: and after the anchor bars are tensioned to a set maximum tensioning load value, the load should be kept stable for 10-15 minutes, and then unloading is carried out to carry out locking operation. The anchorage device and the clamping piece used for locking meet the technical standard and quality requirement. If obvious prestress loss is found, the tensioning should be compensated in time. After the anchor bars are locked, the residual anchor bars need to be mechanically cut, arc burning is strictly forbidden, and the exposed anchor bars with the length of 5-10 cm are reserved to prevent dragging and slipping. And finally, cement paste is used for filling gaps of the anchor backing plate and each part of the anchor head, and the anchor is sealed according to the design requirement, and the anchor is preferably sealed by concrete with the pressure of not less than 20MPa, so that the corrosion is prevented, and the appearance is attractive.
11, monitoring a foundation pit: a detailed foundation pit monitoring scheme is compiled by professional units with qualification according to support design files and requirements of 'construction foundation pit engineering monitoring technical specifications', an observation point is arranged at the side 30m of a foundation pit for vertical and horizontal displacement of the top of the enclosure structure, a water diameter observation well is less than or equal to 30 m/port, and peripheral surface subsidence observation points are arranged less than or equal to 30 m/point.
The monitoring frequency is at least 1 time/1 day during foundation pit excavation and basement structure construction, and real-time tracking monitoring is required when abnormal conditions occur. Monitoring units feed monitoring data back to owners, supervisors, general packages and supporting units for the first time, and the units are dynamically controlled according to the monitoring data.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (10)
1. The foundation pit bag type enlarged footing anchor cable supporting structure is characterized by comprising anchor holes, a support structure, anchor bars, reinforced cement-soil piles and an anchorage device;
the anchor hole is arranged in the side slope, and a retaining structure is arranged on the surface layer of the side slope where the orifice of the anchor hole is located;
the front end of each anchor bar extends to the inside of the anchor hole from the hole opening of the anchor hole, and an anchor plate is fixed at the front end of each anchor bar;
a reinforced cement-soil pile is jet-sprayed at high pressure in the anchor hole, the reinforced cement-soil pile is provided with an expanding head section and an expanding diameter section, the expanding head section is arranged corresponding to the anchor plate, and the expanding diameter section is arranged in the middle of the anchor hole;
the anchor device is fixed on the anchor bar, and the anchor device is abutted to the envelope structure towards one side of the anchor hole.
2. The foundation pit bag type enlarged head anchor cable support construction method according to claim 1, characterized in that: the method comprises the following steps:
1) proportioning cement slurry;
2) forming holes and reaming the rotary jet grouting pile;
3) manufacturing anchor bars;
4) laying an anchor cable;
5) grouting construction;
6) hanging a net on the slope surface, and performing spray anchor construction;
7) manufacturing and installing a prestressed base;
8) tensioning anchor bars;
9) locking the anchor bars;
10) and (5) monitoring the foundation pit.
3. The foundation pit bag type enlarged head anchor cable support construction method according to claim 2, characterized in that: the cement paste comprises the following components in percentage by weight: the cement mixing amount is generally 20-30%, the water cement ratio is generally 0.7-1.0, and the cement slurry is 42.5 grade ordinary portland cement paste.
4. The foundation pit bag type enlarged head anchor cable support construction method according to claim 2, characterized in that: and (3) forming holes and reaming construction of the jet grouting piles: adopting a jumbolter, wherein a high-pressure rotary drill bit and a flank nozzle of the jumbolter are gradually and automatically pushed under the driving of power in the drilling process until the designed depth and diameter are reached; and (3) reaming process: the high-pressure rotary drill bit rotates uniformly, sinks in a uniformly lifting mode, and performs high-pressure injection expansion from top to bottom or from bottom to top.
5. The foundation pit bag type enlarged head anchor cable support construction method according to claim 4, characterized in that: water or cement slurry is adopted in the hole expanding process; when the cement slurry reaming process is adopted: reaming twice up and down; when a clear water reaming process is adopted: and reaming again by adopting cement slurry after reaming by clear water.
6. The foundation pit bag type enlarged head anchor cable support construction method according to claim 2, characterized in that: placing the anchor cable of the jet grouting pile: and (4) arranging steel strands in the anchor pile, sleeving a drill bit into the anchor pile, entering the bottom of the jet grouting pile, and leaving 1.0m of single steel strand outside.
7. The foundation pit bag type enlarged head anchor cable support construction method according to claim 2, characterized in that: grouting construction of the jet grouting pile: the distance from the grout outlet of the grouting pipe to the bottom of the hole is not more than 300mm, grout should be continuously poured from bottom to top, and smooth water and air drainage from the hole should be ensured.
8. The foundation pit bag type enlarged head anchor cable support construction method according to claim 2, characterized in that: stretching the anchor bars: the slope anchor cable is tensioned and locked by a high-pressure oil pump and a piercing jack.
9. The foundation pit bag type enlarged head anchor cable support construction method according to claim 8, characterized in that: and (3) pre-tensioning once by using 20% of locking load before formal tensioning, then tensioning in stages by using 50% and 100% of locking load, then supertensioning to 100% of locking load, keeping for 5 minutes under the supertensioning load, observing that the anchor head has no displacement phenomenon, and then locking according to the locking load.
10. The foundation pit bag type enlarged head anchor cable support construction method according to claim 8, characterized in that: the bearing surface of the anchor bar tensioning anchor inclined supporting pedestal is smooth and vertical to the axis direction of the anchor bar, the anchor device is installed to be closely attached and centered with the anchor backing plate and the jack, the axis of the jack is in a straight line with the anchor hole and the axis of the anchor bar, and the anchor head is prevented from being bent or deflected, so that the uniform and coaxial bearing is ensured.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113668525A (en) * | 2021-09-03 | 2021-11-19 | 中冶成都勘察研究总院有限公司 | Construction method of anti-floating anchor rod with water-drop-shaped enlarged head based on PSB finish-rolled deformed steel bar |
| CN115125969A (en) * | 2022-08-11 | 2022-09-30 | 广州市恒盛建设工程有限公司 | Construction method for pre-stressed anchor cable in soft soil stratum |
| CN115198743A (en) * | 2021-10-19 | 2022-10-18 | 北方工业大学 | Design of optimal proportioning scheme of pea stone mortar anchor disc |
| CN115492097A (en) * | 2022-09-29 | 2022-12-20 | 中国建筑第五工程局有限公司 | Unbonded prestressed anchor cable and construction method thereof |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101575854A (en) * | 2009-06-10 | 2009-11-11 | 陕西中机岩土工程有限责任公司 | High-pressure jet grouting enlarged footing anchor rod and construction method thereof |
| CN105089081A (en) * | 2015-07-20 | 2015-11-25 | 龙元建设集团股份有限公司 | Anti-floating anchor rod construction method |
| CN107190755A (en) * | 2017-07-19 | 2017-09-22 | 上海宝冶集团有限公司 | Disposable high-pressure rotary-spray reinforced cement-soil pile anchor support construction |
| KR102076246B1 (en) * | 2019-07-15 | 2020-02-11 | (주)우진이앤씨 | Anchor hole boring method to emit the crushed slime and the injected water by forming the negative pressure on the slope of the cone-shaped bit |
-
2020
- 2020-05-29 CN CN202010475955.8A patent/CN111676969A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101575854A (en) * | 2009-06-10 | 2009-11-11 | 陕西中机岩土工程有限责任公司 | High-pressure jet grouting enlarged footing anchor rod and construction method thereof |
| CN105089081A (en) * | 2015-07-20 | 2015-11-25 | 龙元建设集团股份有限公司 | Anti-floating anchor rod construction method |
| CN107190755A (en) * | 2017-07-19 | 2017-09-22 | 上海宝冶集团有限公司 | Disposable high-pressure rotary-spray reinforced cement-soil pile anchor support construction |
| KR102076246B1 (en) * | 2019-07-15 | 2020-02-11 | (주)우진이앤씨 | Anchor hole boring method to emit the crushed slime and the injected water by forming the negative pressure on the slope of the cone-shaped bit |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113668525A (en) * | 2021-09-03 | 2021-11-19 | 中冶成都勘察研究总院有限公司 | Construction method of anti-floating anchor rod with water-drop-shaped enlarged head based on PSB finish-rolled deformed steel bar |
| CN115198743A (en) * | 2021-10-19 | 2022-10-18 | 北方工业大学 | Design of optimal proportioning scheme of pea stone mortar anchor disc |
| CN115125969A (en) * | 2022-08-11 | 2022-09-30 | 广州市恒盛建设工程有限公司 | Construction method for pre-stressed anchor cable in soft soil stratum |
| CN115492097A (en) * | 2022-09-29 | 2022-12-20 | 中国建筑第五工程局有限公司 | Unbonded prestressed anchor cable and construction method thereof |
| CN115492097B (en) * | 2022-09-29 | 2024-05-03 | 中国建筑第五工程局有限公司 | Non-bonding prestressed anchor cable and construction method thereof |
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