CN109811771A - Make the simple and easy method not bent when anchor bar steel waist rail tensioning - Google Patents

Abstract

A kind of simple and easy method for making not bend when anchor bar steel waist rail tensioning, the following steps are included: the assembled welding, single tension, gunite concrete of girder steel: spraying full concrete behind to girder steel and form concrete after girder steel, and it is sprayed from the gap before girder steel component to the inner cavity between two I-steel and is full of concrete, form girder steel inner cavity concrete, covering and heat insulating moisturizing solidifies 24~36 hours；It finally carries out two times tensioning: each anchor pole being made to be stretched to 1.4 times of axle power standard value.The invention has the advantages that using in girder steel back fill concrete simultaneously in girder steel lumen loading concrete, reach the method for some strength tensioning again to its solidification, substantially increase the tensile strength of girder steel, solve the problems, such as that girder steel is obviously bent when anchor pole tensioning, and it is convenient and efficient easy to implement, it is low in cost, very reliably.

Description

Make the simple and easy method not bent when anchor bar steel waist rail tensioning

Technical field

The present invention relates to a kind of simple and easy methods for making not bend when anchor bar steel waist rail tensioning, are used for foundation foundation pit In supporting construction in anchor pole stretching construction, bolt grouting body is wanted after reaching some strength in the pile-anchor supporting system of pattern foundation pit supporting structure Prevent the bending of steel waist rail when tensioning fixation, belongs to building engineering construction field.

Background technique

It is well known that pile-anchor supporting system right and wrong are usually in the foundation pit support construction of the realm of building construction foundation A kind of supporting type, especially in deep foundation pit support, for example depth is more than 15m, and foundation pit side just have building, road or Underground utilities etc., soil nail wall or composite soil nailing wall just seem unable to do what one wishes in terms of strict control deformation, and pile-anchor retaining compares underground Diaphragm wall, interlocking pile save money, save trouble, saves the duration, and it is in a disguised form also largely effective to control foundation pit, especially similar to Beijing area this The pan soil stratum area of sample, cost performance are high.It is widely used all the time.

But as urban environment becomes increasingly complex, the building especially residential price around foundation pit is higher and higher, resident And each related side such as Construction Party and government requires to be increasingly stringenter to foundation pit deformation, pattern foundation pit supporting structure deformation is become by past Centimeter Level For present grade.This requires the stake that we design is more and more thicker, increasingly longer, anchor pole bearing capacity is increasing, the body of rod Also just increasingly longer, construction technology is more and more harsh, and also when the river rises the boat goes up for lock value, higher and higher.Pattern foundation pit supporting structure specification (rule Journey) also require it is higher and higher, such as Beijing's provincial standard " building foundation pit supporting technical regulation " (DB11/489-2007) rule Fixed: the maximum finder charge of anti-pulling of anchor bar test should take anchor pole axial direction tensile capacity design value Nd.And it was revised by 2016 Shi Gaiwei: the maximum finder charge of anti-pulling of anchor bar detection test should take 0.8 times of anchor rod ultimate anti-pulling capacity.Professional standard " building foundation pit supporting technical regulation " (JGJ120-2012) regulation: for level-one foundation pit, anchor pole tensioning value and axial tension standard The ratio of value Nk is not less than 1.4；Provide simultaneously: when lacking test data, axis force of anchor when locking can use 1.1 times of lock value ~1.15 times.

The requirement of Beijing 15m design of deep foundation pit: anchor pole tensioning fixation carries out in two times, is stretched to pulling force standard value for the first time 1.4 times after unclamp, second of tensioning be greater than lock value after locked.The foundation pit bosom reaches 16.05m, designs three anchors Bar, wherein the long 23.5m of first of anchor pole, matches 4 15.2 steel strand wires of diameter, free segment length 8m, aperture 150mm, horizontal space 1.6m, axial tension standard value 400kN, lock value 380kN, waist rail is two 25B I-steel, wherein mono- pile of a Duan Yinyou bores Tool, which fractures, causes spacing design bigger than normal to use 32B I-steel.Discovery reaches the 1.4 of axial tension 400kN when by root tensioning Again when i.e. 560kN, girder steel bending is quite severe, including that section of 32B steel I-beam is also only loaded into 552kN, i.e., 1.38 times Severe bends have occurred in girder steel, it has to terminate in advance, it is clear that cannot verify whether the quality of anchor pole meets design requirement, pass through The model girder steel that confirmation uses is crossed to meet the requirements.At this moment, there is one kind in an urgent demand profession subpackage unit in charge of construction easily and fast Method as early as possible puts into practice.

Summary of the invention

It is an object of the invention to provide a kind of simple and easy methods for making not bend when anchor bar steel waist rail tensioning, to solve The prior art is in anchor pole tensioning the problem of girder steel bending.

The technical scheme is that a kind of simple and easy method for making not bend when anchor bar steel waist rail tensioning, feature It is, comprising the following steps:

(1) it the assembled welding of girder steel: is constructing between slope protection pile and stake after sheath, by two I-steel batten plates arranged side by side It is welded to each other composition girder steel component with taper liner block, each taper liner block is corresponding with each slope protection pile；And by the steel strand wires of anchor pole Across two I-steel, conventionally it is put in place；

(2) single tension: in order to which prestressed anchor makes each location contacts close, keeping steel strand wires totally straight, take 10~ 20% design tensile load, to steel strand tension 1~2 time, it is ensured that girder steel component completely hangs up and positions；

(3) gunite concrete: girder steel component bottom plane is repaired it is smooth, after the pad soil of side between the stake sheath and girder steel group " clay model " is formed between on rear side of part, to " clay model " the interior gunite concrete, makes to be full of between sheath between the stake behind girder steel mixed Solidifying soil forms concrete after girder steel；And it sprays and is full of from the gap before girder steel component to the inner cavity between two I-steel Concrete, forms girder steel inner cavity concrete, and covering and heat insulating moisturizing solidifies 24~36 hours；

(4) two times tensioning: each anchor pole is made to be stretched to 1.4 times of axle power standard value.

Sheath includes: the steel mesh being located between two adjacent slope protection piles between the stake, and the both sides of steel mesh pass through implantation Reinforcing bar is connect with slope protection pile；Spray is protected between being coated with stake on steel mesh.

Before carrying out the step (2), multistage girder steel component is welded to each other and is integrated, guarantees its globality.

In the step (3), girder steel bottom surface is modified using small excavator and soil is padded in side, forms " clay model "； Anchor arrangement is sprayed using scene, starts air compressor machine, backstage mix mixture successively sprays after the girder steel in concrete and girder steel Chamber concrete will carry out steel strand wires protection and package isolation work before gunite concrete, must not make to be stained on steel strand wires mixed Solidifying soil；Smoothing out concrete with trowel after having sprayed makes its appearance looks elegant.

Concrete and girder steel inner cavity concrete use after the girder steel cement selection PSA32.5, PSB32.5 or PO42.5, the materials of sheath are identical between stone used and sand and stake, volume ratio are as follows: cement: stone: sand=1:2:2.

In order to reduce dust pollution, the step (3) especially takes " tide spray " technique, i.e., drenches stone sand with water It is wet, jeting effect is not influenced, and avoid dust from flying, is detected through CCZ-1000 dust concentration measuring instrument, dust concentration It can be controlled within 30mg/m3, regular is in 15mg/m3 or so, it can be achieved that worker does not wear anti-dust mask operation.

The model of I-steel in the girder steel component includes 25B, 28B or 32B, or uses smaller number.

The I-steel can also be used the channel steel that two notches are oppositely arranged and replace, concrete and steel after the girder steel Beam inner cavity Concrete Filled C30~C40 concrete.

The invention has the advantages that use in girder steel back fill concrete simultaneously in girder steel lumen loading concrete, to It solidifies the method for reaching some strength tensioning again, the tensile strength of girder steel is substantially increased, when efficiently solving anchor pole tensioning The problem of girder steel is obviously bent, and it is convenient and efficient easy to implement, it is low in cost, very reliably.

Detailed description of the invention

Fig. 1 is the foundation pit of the embodiment of the present invention and the pile-anchor retaining plan view on periphery；

Fig. 2 is F direction view (part) in Fig. 1；

Fig. 3 is the enlarged drawing in Fig. 2 at N；

Fig. 4 is the E-E cross-sectional view of Fig. 2；

Fig. 5 is the enlarged drawing in Fig. 4 at P；

Fig. 6 is the schematic top plan view of Fig. 5.

Description of symbols: 1- crown beam, 2- retaining wall, 3- waterwall, 4- banket wall, first of anchor pole of 5-, 6- second Anchor pole, 7- third road anchor pole, 8- slope protection pile, 9- bearing plate, 10- anchor head, 11- I-steel, 12- taper liner block (angle board), 13- steel Net, sprays shield between 14-, and 15- is implanted into reinforcing bar, concrete after 16- girder steel, 17- closing foundation ditch building basis, and 18- steel strand wires, 19- sews Plate, 20- girder steel inner cavity concrete, sheath between 21, stake, A, slope protection pile stake position (stake holes), B, foundation pit are suitable for reading, mouth under C, foundation pit, D, Raft edges of boards line, a, clay model side, b, clay model bottom surface.

Specific embodiment

Referring to Fig. 1-Fig. 6, a kind of simple and easy method for making not bend when anchor bar steel waist rail tensioning of the present invention, specific practice It is: is constructing between slope protection pile 8 and stake after sheath 21, recycles jumbolter that will design anchor bolt construction and complete；By girder steel component Assembly welding, it may be assumed that two I-steel 11 arranged side by side are welded to each other composition with multiple batten plates (i.e. connecting plate) 19 and taper liner block 12 Girder steel component (in the solderable batten plate 19 in the two sides of I-steel 11), each taper liner block 12 is corresponding with each slope protection pile 8；And By the steel strand wires 18 of anchor pole mechanism across two I-steel 11, conventionally it is put in place.

In order to which prestressed anchor makes each location contacts close, keep steel strand wires 18 totally straight, takes 10~20% design Tensile load, to its tensioning 1~2 time, it is ensured that girder steel component completely hangs up and positions.It at this time can will often two sections of girder steel components Welding is linked together, and guarantees its globality.

Smooth using small excavator amendment girder steel component bottom plane a, side b suitably pads soil and forms " clay model ", is sprayed using scene Anchor arrangement starts air compressor machine, and backstage mix mixture carries out gunite concrete, makes to spray full concrete behind girder steel, is formed Concrete 16 after girder steel；And laterally spray girder steel inner cavity, make its it is intracavitary be also filled with concrete, form girder steel inner cavity concrete 20. The protection of steel strand wires 18 and package isolation work are carried out at this time, must not make to be stained with concrete on steel strand wires 18.Trowel is used after having sprayed Floating makes its appearance looks elegant, and covering and heat insulating moisturizing waits to be solidified.

PSA32.5, PSB32.5 can be selected in the cement of concrete 16 and girder steel inner cavity concrete 20 after forming girder steel, or is Working to tight deadlines makes its condensation faster, it is possible to use materials are identical when between PO42.5, stone and sand and scene spray soil nail wall and stake Can (volume ratio are as follows: cement: stone: sand=1:2:2), without individually charging, time saving economical and efficient easy to operate of saving trouble.Its In in order to reduce dust pollution, especially take " tide spray " technique, i.e., stone sand drenched with water, do not influence jeting effect, And avoid dust from flying, through CCZ-1000 dust concentration measuring instrument detect, dust concentration can be controlled in 30mg/m3 it Interior, regular is in 15mg/m3 or so, it can be achieved that worker does not wear anti-dust mask operation.

It is general only to need 24~36 hours after its solidification reaches some strength, tensioning can be carried out to anchor pole, completely in anchor In bar curing period, the duration is not occupied individually.Even if each anchor pole is stretched to 1.4 times of axle power standard value, girder steel will not go out Now it is bent.

To efficiently smoothly complete anchor pole stretching construction, realize that each anchor pole is stretched to 1.4 times of axle power standard value, Girder steel is not in bending purpose.

Construction machinery equipment include air compressor machine, shotcrete machine, small excavator, spade, pipeline and spray gun, trowel, spray head and Electric welding equipment etc..

Another advantage is that deep foundation ditch anchor rod girder steel can also be used smaller number using models such as 25B, 28B, 32B, For example 20B, 22B etc. are not only brought convenience due to light, but also can save the high money of next record, economy is very aobvious It writes.By taking this engineering as an example, 25B I-steel 540.8m, 28B I-steel 1181.6m, 32B I-steel 72m, theoretical weight difference For 42.03,47.888,57.741kg/m, and 20B theoretical weight is 31.069kg/m.I-steel can be saved after replacement 27721.38kg can be saved 116429.8 yuan, be accounted for 33.2% by 4200 yuan/T of current market valence.It is one third.More preferably It fills C30~C40 concrete thereafter using channel steel, can more save half or more.It compares to save with reinforced concrete waist rail and tie up The complicated cumbersome process such as reinforcing bar formwork supporting plate casting concrete, and save the maintenance waited long and condensation and intensity is waited to mention More than half can be improved in high time, timeliness.

4. embodiment

4.1 project profile

Beijing Institute of Technology Zhong Guan-cun school district Hospital transformation project is located at No. 5, Zhongguancun Road(South), Haidian District, Beijing City north In the school, place east side is hostel for capital Polytechnics, and southern side is Seeking Truth building and sports ground, and west side is Radix Polygalae building and shop, north side For No. 1, No. 2 residential buildings.This engineering ± 0.00=52.700m.This engineering is made of Hospital and rainwater storage tank two parts.

This base pit engineering is gib, and design life is 1 year.

4.2 surrounding enviroment

(1) foundation pit north side is distributed more underground utilities (heating pipeline, water-supply line, sewage pipeline) and phase shut-in valve is set It applies, north side eastern section is No. 1 residential building, and north side west section is No. 2 residential buildings.Underground utilities away from ready-built structure outer rim minimum distance about 2.40m, using direct-buried mode, buried depth is less than 2.00m；No. 16 floor of residential building ground, about away from ready-built structure outer rim minimum distance 9.70m, C10 concrete continuous footing, 50.15~49.10m of substrate absolute altitude；No. 25 floor of residential buildings ground, away from ready-built structure outer rim Minimum distance about 6.10m, C15 concrete continuous footing, substrate absolute altitude 48.80m.

(2) foundation pit east side is Polytechnics Road, hostel and dormitory.Buried pipe is buried under Polytechnics Road Line, away from ready-built structure outer rim minimum distance about 13.0m, using direct-buried mode, buried depth is less than 2.00m；Hostel and dormitory 6 layers on the ground, away from ready-built structure outer rim minimum distance about 20.00m, C20 concrete continuous footing, substrate absolute altitude 50.44m.

(3) foundation pit southern side be distributed more underground utilities (power electric, light current, heating pipeline, water-supply line, rainwater pipeline) and Phase shut-in valve facility, southern side eastern section are Seeking Truth building, and southern side west section is sports ground.Underground utilities are away from ready-built structure outer rim minimum distance About 4.00m, using direct-buried mode, buried depth is less than 2.00m；1~4 floor of Seeking Truth building ground, about away from ready-built structure outer rim minimum distance 21.50m, C20 concrete isolated footing, substrate absolute altitude 50.00m；Sports ground is just in using area, and site elevation is about 52.40m。

(4) foundation pit west side is distributed more underground utilities (power electric, light current, rainwater pipeline) and phase shut-in valve facility, west side Northern section is science and engineering dining room and integrated service building, and west side south section is Radix Polygalae building.Underground utilities away from ready-built structure outer rim minimum distance about 2.80m, using direct-buried mode, buried depth is less than 2.00m；Science and engineering dining room and integrated service building 1~2 floor on the ground, away from ready-built structure outside Edge minimum distance about 8.30m, C20 concrete continuous footing, 50.40~49.50m of substrate absolute altitude；4 floor of Radix Polygalae building ground, away from quasi- Build structural outer rim minimum distance about 7.30m, C20 concrete continuous footing, substrate absolute altitude 50.60m.

4.3 engineerings and hydrogeologic condition

Stratum soil property is summarized

Reported according to geotechnical engineering investigation, top is fill stratum, under be to rush proluvial in recent deposit layer, the general Quaternary Period Layer.Formation is as follows from top to bottom:

1) ※ 1. artificial earth fill layer

1. clay silt plain fill: isabelline, based on clay silt, sandy silt, part is Extra-fine sand, contains a small amount of brick Slag, lime-ash, plant roots and stems etc..Wet, loosely, part presss from both sides 1. 1 miscellaneous fill.This layer of overall thickness is 1.20~7.20m, and layer bottom absolute altitude is 45.28~51.15m.

1. 1 miscellaneous fill, variegated, based on building, containing brick, lime-ash, rubble etc., wet, loosely organized, maximum gauge is 0.70m。

2) ※ 2.~7. the general Quaternary Period rush diluvial formation

2. clay silt, sandy silt: it is isabelline, it is wet containing mica, iron oxide etc., it is slightly close~in close, height~mesohigh contracting Property, this layer presss from both sides 2. 1 silty clay, heavy silt clay lenticular body.The distribution of this layer is discontinuous, and the general thickness of exposure is 0.60~ 5.70m, layer bottom absolute altitude are 45.14~46.76m.2. 1 silty clay, heavy silt clay, isabelline, contain mica, iron oxide etc., It is wet~very wet, soft modeling~plastic, height~mesohigh contracting, maximum gauge 0.70m.

3. Extra-fine sand: it is isabelline, it is wet containing mica etc., in it is close~closely knit, this layer is with a thickness of 5.00~7.70m, layer bottom absolute altitude For 39.03~40.26m.

4. cobble: variegated, sub- round, partial size is generally 6~9cm, and maximum particle diameter is not less than 11cm, and medium coarse sand fills about 30%, it is wet~saturation, it is slightly close~in close, 6.20~7.30m of thickness, layer bottom 32.82~33.43m of absolute altitude.

5. silty clay, heavy silt clay: isabelline, wet~very wet containing mica, iron oxide etc., plastic, middle high~middle pressure Contracting, for this layer with a thickness of 1.50~2.40m, layer bottom absolute altitude is 30.75~31.83m.

6. Extra-fine sand: isabelline, containing mica etc., wet, closely knit, this layer is with a thickness of 1.90~3.60m, layer bottom absolute altitude 27.72~29.23m.

7. cobble: variegated, sub- round, partial size is generally 6~10cm, and maximum particle diameter is not less than 12cm, and medium coarse sand fills about 30%, it is wet~saturation, in it is close~closely knit.The layer is not exposed, and maximum discloses with a thickness of 11.90m.

Hydrogeologic condition

1) two layers of underground water is disclosed in drilling depth range during this prospecting, first layer groundwater type is diving, is contained Water layer is that 4. boulder bed, fixed level buried depth are 19.10~19.40m, and absolute altitude is 33.14~33.25m.Second layer underground water Type is diving, and water-bearing layer is that 7. boulder bed, fixed level buried depth are 29.50m, absolute altitude 23.04m.

2) this place nineteen fifty-nine historical high groundwater level is once close to natural terrain, nearly 3~5 years highests groundwater level absolute altitude About 38.00m, water level year amplitude of variation about 1.00~2.00m.

3) according to underground water corrosion classsification result judgement: environmental form is this place first layer, second under the conditions of II class Layer underground water all has microcorrosion to concrete structure；This place first layer, second layer underground water under Wet/Dry Cyclic Conditions Microcorrosion is all had to the reinforcing bar in reinforced concrete structure.

4) analyze result judgement according to the lyotropic salt of soil: soil has microcorrosion to concrete structure；Soil is to reinforced concrete Reinforcing bar in soil structure has microcorrosion.

4.4 engineering emphasis and difficult point

This construction project is located in Haidian District Zhong Guan-cun South Street, is located at bustling location, pattern foundation pit supporting structure and earth excavation work Amount is big, and foundation depth reaches 15m.Line of project and periphery traffic administration is stringent, construction of structures is complicated, surrounding building is apart from foundation pit Relatively close, soil deformation control in foundation pit periphery requires strictly, wherein it is ensured that the safety and stability of deep pit monitor stabilization and periphery structures It is the outstanding feature of this engineering.

4.4.1 most important to the protection of Adjacent Buildings, structures and underground utilities

(1) after marching into the arena, the buildings or structures closed on are carried out to go deep into detailed investigation and prospecting, further verify to close on and build (structure) builds object and the relationship (including plane relation, absolute altitude relationship etc.) of foundation pit, foundation pattern, further to design perfect.Root It is investigated according to us, nearby residents building does not have shock resistance, therefore the vibration reduced as far as possible to neighboring buildings that need to adopt an effective measure It destroys.Following measures can be used to construct:

1) the slope protection pile constructing process for using rotary drilling rig mud off pore-forming, shortens the piling duration, reduces slope protection pile and applies Influence during work to surrounding enviroment.

It 2), when necessary can be in anchor bolt construction using casing follow-up construction in order to avoid collapse hole when sand pebble layer anchor bolt construction Technique, and timely slip casting reduce the factor of Nearby Structure basis and surrounding soil unstability is caused to exist as far as possible.

(2), to the buildings or structures closed on, qualified authority's monitoring unit (independent third party) is cooperated to carry out the change of structure Shape and settlement monitoring；It takes and buries inclinometer in pile body, the method for installing anchor axial force meter takes advanced digital level And Foundation pit monitoring analysis system, fast and accurately processing is carried out to monitoring data and is analyzed, and promptly draws out curve, in time Multidate information and prediction are provided for supporting construction, the safety for closing on buildings or structures, thus using information-aided construction as this engineering The advantageous guarantee of supporting construction safety.

Prestressed anchor construction precautions

There are existing building in this foundation pit north side, west side, and closer from foundation pit, calculate through designing unit, and each supporting section is answered in advance There is no collisions for power anchor pole and adjacent buildings foundation structure.Pore-forming uses jump to play construction when anchor bolt construction at this, every three dozens One, timely slip casting, slip casting could construct adjacent anchor pole after completing 24 hours.

Since foundation pit surrounding underground utilities are more, when anchor bolt construction encounters barrier, it must stop constructing immediately and search Reason formulates corresponding treatment measures, avoids generating adverse consequences.

Process choice

It is clay, Extra-fine sand, silty clay within the scope of anchor bolt construction, cobble etc., proposed adoption common bolt drilling machine does operation First of anchor pole of constructing guarantees not play mudcake in work progress using mud jacking mechanical hole building technique.Bolt grouting uses minute-pressure Slip casting combination secondary pressure grouting process.

Due to firm hard formations such as cobbles, second anchor pole down, is constructed using with drill machine with casing.In the same of earthwork construction When, it stays and sets anchor bolt construction working face (500mm below anchor position).Scene need to carry out dynamic according to the practical drilling situation of anchor bolt construction Adjustment guarantees anchor bolt construction speed and quality.When being related to different geological stratifications, anchor pole test boring should be carried out in advance, for pore-forming Situation adjusts drilling machine type selecting in time.

Dry construction process flow

Casing wet construction process flow

Drilling machine is in place-→ to be corrected hole location adjustment angle-→ opening water source-→ drilling-→ and proposes interior drilling rod punching repeatedly Wash-→ and connect inner sleeve drilling rod and outer tube-→ continue drilling to design hole depth-→ borehole cleaning-→ and cut off the water, pull out interior drilling rod-→ It inserts steel wire bundle and Grouting Pipe-→ grouting methol-→ with drawbench and pulls out outer tube and second pulp feeding-→ secondary pressure Slip casting-→ maintenance-→ installation steel waist rail and anchor head-→ prestressed stretch-draw locking

Tensioning fixation

Pressure-bearing surface is answered smooth and vertical with anchor pole axis direction.Anchor pole tensioning should when injecting cement paste intensity reaches 20MPa into Row.Tensioning key step should be carried out by design requirement.

To keep each unit rockbolt stress uniform, it should fall each unit anchor pole first to each unit anchor pole gradation tensioning when compensation and exist Under same load, after the displacement difference because caused by not waiting freedom length, then integral tension.

Locking load is determined by design requirement.If after rock bolt, prestress value variation is greater than 10%, it need to loosen or repeat Tensioning.

Before prestressed anchor tensioning, tensioning equipment should be demarcated.Prestressed anchor tensioning should be carried out by established procedure, In layout stressing sequence, it is considered as influencing each other for adjacent drilling prestressed anchor tensioning.Before the formal tensioning of prestressed anchor, The design tensile load that 20% should be taken keeps its each location contacts close, keeps steel strand wires totally straight to its pre- tensioning 1~2 time.

In the anchor pole of this engineering, tentative tensioning is carried out by different anchor pole types, each type anchor pole takes 3, tensioning It to design load, then locks, lock value is given by design drawing, then carries out the tensioning of Engineering anchor rod.Anchor pole tensioning fixation is divided to two Secondary progress is unclamped after being stretched to 1.4 times of pulling force standard value for the first time, and second of tensioning is locked after being greater than lock value.Consider To will appear when anchor pole tensioning amount of recovery (i.e. centainly locking load loss), it is necessary to carry out ultra stretching.About more than tensioning The specific value of locking must cooperate monitoring instrument to determine by field test using oil hydraulic system.

If it was found that tensioning should be compensated when having apparent loss of prestress.After anchor pole tensioning fixation, end tensioning section is not It must truncate, in case supplement tensioning uses.

4.4.2 engineering monitoring

Illustrated according to design document, before Foundation Pit Construction, Construction Party committee should ask the third party for having corresponding qualification to base Engineering construction field monitoring is cheated, unit in charge of construction should also carry out necessary construction monitoring in the construction process, and field monitoring should use The method that instrument monitoring is combined with walkaround inspection is carried out by " architecture Foundation Pit Engineering Specifications of Monitoring Technology " (GB50497-2009) The monitoring of foundation pit.

4.4.2.1 monitoring content

(1) top of the slope level, vertical displacement monitoring；(2) stake top level, vertical displacement monitoring；(3) support pile deep water prosposition Move monitoring；(4) anchor pole Internal Force Monitoring；(5) Ground Settlement monitors.

4.4.2.2 monitoring instrument

The main monitoring instrument of serial number monitoring project

Latitude ZT80MR+ (total station) in 1 displacement monitoring

2 settlement monitoring DSZ2 and FS1 (mircrometer gauge)

The same observation people of same instrument is remained in observation, the instrument centering for avoiding the exchange of personnel and instrument from generating The collimation error of error and personnel.

4.4.2.3 monitoring method

The displacement of this engineering level is measured using total station.In view of the required precision of monitoring, straight-line method is used as far as possible (and survey station point is arranged in monitoring body in a straight line, 2 angle value is being measured far from selection both direction point outside foundation pit, one is making To check whether survey station point has variation, the second is the initial value as orientation point and tested fixed point and survey station).Individual points are using small Angular distance method (monitoring body opposite set up 2 survey station points, respectively each survey station point measure each monitoring point side length, can Directly to reflect every plan-position variation, it is ensured that number by the mis-tie misclosure and side length intersection value that resolve every triangle According to accuracy).

First time survey measurements twice, the initial value after being averaged as this engineering monitoring data.Later each time can be single Journey observation, as data have exception, i.e., conscientious repetition measurement.Observation method measures every height using settlement observation datum mark as Fixed Initial Point Then this height value is subtracted last time height value by journey, obtain sedimentation variable quantity.

(1) settlement observation

It is measured using accurate level.It is mainly carried out using precise leveling method, settlement observation point is direct It is arranged in the characteristic point of object being observed (such as soil body slope surface, building), and base is being set far from foundation pit or stable position On schedule.Observation point should be arranged in the place (such as foundation pit external corner) with characteristic point.

(2) horizontal displacement observation

It is measured using total station.Use axis projections method between two stable datum marks line for benchmark line, Measure difference and accumulative displacement amount.Observation point is directly arranged in slight slope top of the slope or stake top coupling beam.

(3) anchor axial force monitors

Before anchor pole tensioning, anchor stress sensor is installed at backing plate, then anchor head is installed outside anchor stress sensor Carry out tensioning fixation.

(4) supporting construction deep biosphere

Monitoring point is set in foundation pit slope protection stake, is supervised using the measuring instrument JTM-U10A reading equipment of third party monitoring It surveys, after each issue of monitoring, editor's " monitoring daily sheet ".The displacement of each monitoring point is positive value in table, indicates monitoring point to base Cheat interior direction offset；Conversely, indicating to deviate to foundation pit lateral direction.

(5) live inspection

Since the construction quality of supporting construction, the change of execution conditions, the variation of foundation pit side preloading, construction water are inappropriate The change of discharge, pipeline leakage and weather conditions, there are also the hidden dangers in project such as unstability of ground fractures, supporting construction, closes on and builds Building object crack etc. can all find in time in inspection work, therefore inspection is particularly significant and necessary, Ying Youyou experience Engineer carry out inspection on schedule, inspection work should be included in surveillance program, carry out on schedule, and hold the record.

Monitoring, alarming value and emergency measure

Monitoring frequency

The flat rate of the monitoring of horizontal displacement are as follows: before being excavated to the 1/2 of depth: 1 time/2 days；It is excavated to substrate to complete before stablizing: 1 Times/day；It completes before being completed after stablizing to structure base slab: 1 time/3 days；Before being completed after the completion of structure base slab to backfill: 1 time/15 days.

The flat rate of the monitoring of vertical displacement are as follows: before being excavated to the 1/2 of depth: 1 time/2 days；It is excavated to substrate to complete before stablizing: 1 Times/day；It completes before being completed after stablizing to structure base slab: 1 time/3 days；Before being completed after the completion of structure base slab to backfill: 1 time/15 days；

The flat rate of the monitoring of supporting construction deep biosphere are as follows: before being excavated to the 1/2 of depth: 1 time/2 days；It is excavated to substrate It completes before stablizing: 1 times/day；It completes before being completed after stablizing to structure base slab: 1 time/3 days；It is completed after the completion of structure base slab to backfill Before: 1 time/15 days；

The flat rate of the monitoring of axis force of anchor are as follows: before being excavated to the 1/2 of depth: 1 time/1 day；It is excavated to substrate to complete before stablizing: 2 Times/day；It completes before being completed after stablizing to backfill: 1 times/day.

Monitoring data must accomplish that in time, accurately and completely note abnormalities phenomenon, reinforce monitoring；

Monitoring data such as meet or exceed alarming value and should circularize all the parties concerned in time, to guarantee of adopting an effective measure as early as possible This engineering progress is smooth.

Safety and patrol

(1) base pit engineering walkaround inspection should include following main contents:

1) supporting construction

A. supporting construction Forming Quality；

B. there is free from flaw appearance；

C. whether there is or not depression, crack and slidings for the soil body after wall；

D. whether top of the slope, bottom of slope have ponding, whether have underground water leakage phenomenon on branch mask.

2) construction operating condition

A. the soil property situation of exposure and geotechnical investigation report have indifference after excavating；

B. whether excavation of foundation pit section length, lift height and soil nailing setting are consistent with design requirement；

C. whether ground preloading is greater than limiting design value around foundation pit.

3) foundation pit surrounding environment

A. whether there is or not damaged, leakage scenarios for underground piping；

B. whether there is or not newly-increased cracks to occur for surrounding building；

C. peripheral path (ground) has free from flaw, depression.

4) monitoring facilities

A. the intact situation of datum mark, measuring point；

B. whether there is or not the barriers for influencing observation work；

C. the intact and protection situation of monitoring element.

(2) method of walkaround inspection is aided with the Work tools such as hammer, pricker, gage, magnifying glass and camera shooting, takes the photograph based on estimating Shadow etc. measures.

(3) the walkaround inspection situation of natural conditions, supporting construction, construction operating condition, surrounding enviroment, monitoring facilities etc. should be done Record easy to remember.Inspection record should arrange in time, and combine monitoring data comprehensive analysis.

(4) walkaround inspection such as notes abnormalities and dangerous situation, should notify design side and other relevant units in time.

4.5 field conduct situations and pit retaining monitoring result

First of anchor bolt construction since on July 16th, 2018, until first of anchor pole tensioning on July 23, all uses Girder steel back gunite concrete, and in girder steel inner cavity gunite concrete, waiting is most 36 hours short, and tensioning reaches anchor axial force mark 1.4 times of quasi- value, off-load later is stretched to again to be locked greater than lock value.By taking aforementioned representative section as an example:

First of anchor pole axial tension standard value is 400kN, is stretched to 560kN；

Second anchor pole axial tension standard value is 540kN, is stretched to 756kN；

Third road anchor pole axial tension standard value is 610kN, is stretched to 854kN.

Due to using the patented technology, girder steel back be jetted into concrete, setting time 36h, post-stretching, root Root reaches 1.4 times of anchor pole axial tension standard value, and girder steel is not bent, it is ensured that anchor pole quality ensures that base Hole displacement ensures that the safety such as foundation pit periphery construction of structures road piping in limitation range.

It digging through third party monitoring foundation pit to slot bottom and floor of having constructed, only one point of maximum horizontal displacement reaches 4mm, remaining Point displacement is in 2~3mm.It can be seen that the pattern foundation pit supporting structure is extremely successfully.

Claims (8)

1. a kind of simple and easy method for making not bend when anchor bar steel waist rail tensioning, which comprises the following steps:

(1) the assembled welding of girder steel: between slope protection pile of having constructed (8) and stake after sheath (21), by two I-steel arranged side by side (11) composition girder steel component, each taper liner block (12) and each slope protection pile are welded to each other with batten plate (19) and taper liner block (12) (8) corresponding；And the steel strand wires of anchor pole (18) are conventionally put in place across two I-steel (11)；

(2) single tension: in order to which prestressed anchor makes each location contacts close, keep steel strand wires totally straight, take 10~20% Design tensile load, to steel strand tension 1~2 time, it is ensured that girder steel component completely hangs up and positions；

(3) gunite concrete: girder steel component bottom plane is repaired it is smooth, after the pad soil of side between the stake sheath (21) and girder steel group " clay model " is formed between on rear side of part to be made to fill between sheath (21) between the stake behind girder steel to " clay model " the interior gunite concrete Full concrete forms concrete (16) after girder steel；And it is sprayed from the gap before girder steel component to the inner cavity between two I-steel Concrete is penetrated and be full of, is formed girder steel inner cavity concrete (20), covering and heat insulating moisturizing, is solidified 24~36 hours；

(4) two times tensioning: each anchor pole is made to be stretched to 1.4 times of axle power standard value.

2. the simple and easy method according to claim 1 for making not bend when anchor bar steel waist rail tensioning, which is characterized in that institute Sheath (21) includes: the steel mesh (13) being located between two adjacent slope protection piles (8) between the stake stated, and the both sides of steel mesh (13) pass through Implantation reinforcing bar (15) is connect with slope protection pile (8)；(14) are protected in spray between being coated with stake on steel mesh (13).

3. the simple and easy method according to claim 1 for making not bend when anchor bar steel waist rail tensioning, which is characterized in that Before carrying out the step (2), multistage girder steel component is welded to each other and is integrated, guarantees its globality.

4. the simple and easy method according to claim 1 for making not bend when anchor bar steel waist rail tensioning, it is characterised in that: institute In the step of stating (3), girder steel bottom surface is modified using small excavator and soil is padded in side, forms " clay model "；It is sprayed using scene Anchor arrangement, starts air compressor machine, and backstage mix mixture successively sprays concrete (16) and girder steel inner cavity coagulation after the girder steel Native (20) will carry out steel strand wires protection and package isolation work before gunite concrete, must not make to be stained with coagulation on steel strand wires Soil；Smoothing out concrete with trowel after having sprayed makes its appearance looks elegant.

5. the simple and easy method according to claim 1 for making not bend when anchor bar steel waist rail tensioning, it is characterised in that: institute Concrete (16) and girder steel inner cavity concrete (20) use after the girder steel stated cement selection PSA32.5, PSB32.5 or PO42.5, the materials of sheath (21) are identical between stone used and sand and stake, volume ratio are as follows: cement: stone: sand=1:2: 2。

6. the simple and easy method according to claim 1 for making not bend when anchor bar steel waist rail tensioning, it is characterised in that: its In in order to reduce dust pollution, the step (3) especially takes " tide spray " technique, i.e., drenches stone sand with water, no Jeting effect is influenced, and avoids dust from flying, is detected through CCZ-1000 dust concentration measuring instrument, dust concentration is controllable Within 30mg/m3, regular is in 15mg/m3 or so, it can be achieved that worker does not wear anti-dust mask operation.

7. the simple and easy method according to claim 1 for making not bend when anchor bar steel waist rail tensioning, it is characterised in that: institute The model of I-steel (11) in the girder steel component stated includes 25B, 28B or 32B, or uses smaller number.

8. the simple and easy method according to claim 1 for making not bend when anchor bar steel waist rail tensioning, it is characterised in that: institute The I-steel (11) stated can also be used the channel steel that two notches are oppositely arranged and replace, concrete (16) and girder steel after the girder steel Inner cavity concrete (20) fills C30~C40 concrete.