Shield construction be a kind of use shield machine at underground driving, when preventing the avalanche of soft ground excavation face or keeping the excavation face stable, in machine, carry out a kind of of the excavation in tunnel and lining cutting operation safely in the bored tunnel job practices.
Shield launching and arrival technology be meant before shield driving to the portal termination take to handle that (reinforcing soft stratum and phreatic high geological conditions), portal cut, shield launching and receive design processing, the location and installation of pedestal; The installing of support system, portal ring, shield machine assembly and disassembly measure, thus the construction technology that shield-tunneling construction can tunnel and arrive according to the Tunnel Design axis guaranteed.
The shield machine closed origin of domestic present use and arrival job practices are many, use three kinds of maximum methods to be for carrying out shield launching in the soft stratum: agitation pile (rotary churning pile) reinforcing method, steel sheet pile displacement method, freezing process portal reinforcing method.
(1) agitation pile (rotary churning pile) reinforcing method
Agitation pile (rotary churning pile) reinforcing method is meant the method that adopts cement mixing pile or rotary churning pile that the portal ground is reinforced, and reinforcing scope mainly is the shield machine closed origin and arrives tip position, exceeds the length and the width range of shield machine.This reinforcement means is to use maximum methods in the portal reinforcement means of existing shield launching, than other traditional reinforcing method, and characteristics such as construction technology is simple, and relatively economical is profitable.
Yet this reinforcement means still exists the reinforcing amount big, duration high churning pressure long, relatively poor to the compliance of part special geologic condition, rotary churning pile may make the starting well structure produce distortion or to shortcomings such as surrounding building and pipeline exert an influence, and construction needs bigger construction plant.In addition, if the shield tunnel buried depth is dark or in water-rich sand layer the time, the consolidation effect of this kind worker method is difficult to guarantee, thereby can't guarantee to evade fully the risk of shield launching and arrival.
This worker's method is applicable to most shield launching and arrives the worker's method of reinforcing.
(2) freezing process
Freezing process is that the inhomogeneous ground under the nature is freezed to become the material with even mechanical property by machinery, with the improvement ground.In pre-construction frozen region, bury cryovial underground with the spacing of 60cm～100cm, by freezing plant the salt solution (calcium chloride water) of cooling is circulated in cryovial, make ground freeze to solidify.
The freezing process portal is reinforced major advantage: the frozen soil wall that the process frozen ground forms is by temperature control, can guarantee to be in for a long time stable state, and frozen soil wall good uniformity, the intensity height, can effectively solve the weakness that the inhomogeneous and local weak band of the soil body that methods such as adopting agitation pile, slip casting, churning reinforce can not shutoff pressure muddy water, the geological conditions that is adapted at having drifting sand layer uses down.
It mainly has problems:
Its freezing period, generally need 40d～60d when 1. adopting freezing to carry out stratum consolidation, and construction period is longer, and the mechanical a large amount of electric energy of needs use that freezes, and increased construction cost greatly thereby make.
2. the soil layer frost heave that causes of construction freezing method is bigger to the influence of surrounding environment.Most soil layers all will produce frost heave when freezing, how much relevant the size of frost heaving amount is with soil layer mechanical characteristic, constraints, constraint speed, soil moisture in layer and water translocation, the volume expansion amount that water becomes ice is about 9%, and the soil expansion amount generally is about 3%～4%, the scope of influence also can feed through to non-permafrost region 1m～1.5m, so the protuberance that may the cause ground destruction of pipeline on every side.Secondly, start finish after because the thawing of frozen region ice cube and the freezing pipe space after extracting can cause the thaw collapse of soil layer, cause the sedimentation on the face of land.
This worker's method is applicable to most shield launching and arrives the worker's method of reinforcing.
(3) steel sheet pile displacement method
The steel sheet pile displacement method is meant to be provided with and seals up a door that at portal circle arranged outside steel sheet pile, steel sheet pile is closely arranged and be closely connected with the borehole wall in portal circle scope.Before the shield launching at the good water-stopping system of portal circle installed inside, treat that preparation is finished after, with dismountings of sealing up a door in the circle of hole, the shield structure heads in the hole encloses.The shield machine otch stopped shield machine running at about 200 o'clock apart from steel sheet pile, adjusted antipriming and utilized inert slurry that the hole is enclosed and pull out steel sheet pile after internal pore is filled up.
The steel sheet pile displacement method is carried out in the shield launching process, and steel sheet pile plays the effect of retaining soil, sealing, because shield machine has entered in the circle of hole before pulling out steel sheet pile, and utilizes mud to carry out retaining wall, has avoided the direct exposure of main body, has prevented caving in of the soil body.But adopt the steel plate displacement method that certain limitation is also arranged, for example the duration that takies when carrying out the extracting of steel sheet pile is long, site requirements is high and big to the disturbance of the soil body, use under the nearer situation of building around, " kowtowing " phenomenon or the like problem easily take place behind the shield machine closed origin.
This worker's method is applicable to most shield launching worker method, and the shield structure arrives this kind worker method that do not adopt as yet that receives.
The specific embodiment
The job practices of a kind of shield machine closed origin and arrival, its method step is as follows:
(1): be close to the diaphragm wall space enclosing structure and do the plain concrete diaphragm wall;
(2): on portal, beat oblique peripheral peep hole, observe soil stabilization and seepage situation;
(3): segmentation cuts concrete and the reinforcing bar on the portal, replaces former diaphragm wall with plain concrete simultaneously;
(4): the shield machine receiving system is installed, and is applied pre-applied force;
(5): in the steel bushing of receiving system, carry out filler to requiring height;
(6): steel bushing is carried out voltage-withstand test;
(7): the shield machine tunneling construction enters or breaks away from portal up to the shield machine shield tail;
(8): the steel bushing to receiving system carries out release, disassembles;
For ease of the present invention is further understood, now describe the present invention in conjunction with specific embodiments.
This worker method is applied to two, No. eight line extended line engineerings of Guangzhou track traffic shield structure, 3 bid sections [ventilating shaft, station, Nanpu～shield structure interval, Luo Xi station in the middle of station, Nanpu～south meeting] Luo Xi station shield structure and hangs out well, is applied to station, this bid section Nanpu～two shield machines in shield structure interval, Luo Xi station and arrives and receive.
(1), is close to the diaphragm wall space enclosing structure and does the plain concrete diaphragm wall: stand near one thick plain concrete diaphragm wall of 1200mm of portal space enclosing structure diaphragm wall outside construction at Luo Xi; Width is each 4m about the tunnel center line, add the solid degree of depth from following 2m at the bottom of the tunnel to ground.2 Φ, the 800 two-tube rotary churning pile interlock 200mm that respectively construct at plain concrete diaphragm wall two ends then are with former station space enclosing structure and newly be each interlock 200mm of plain concrete diaphragm wall.
(2), on portal, beat oblique peripheral peep hole, observe soil stabilization and seepage situation: in order to understand portal the inside soil stabilization and seepage situation, gush when preventing to cut portal, after shield machine is rebuffed, need beat peripheral peep hole before portal cuts on portal, the stability and the water permeability of the place ahead soil body determined in the hole according to the observation, and peep hole is arranged by the last mode of how lacking down, the degree of depth is to enter plain concrete diaphragm wall 60mm～100mm, and angle is with 10 ° of the bests.Peep hole passes the space enclosing structure diaphragm wall, earlier bored space enclosing structure with matter flatly, 50 millimeters in aperture, in the oblique layout of the boring at portal edge, outside the portal scope, take out the integrality that core is observed space enclosing structure, and former space enclosing structure and the situation that is connected that increases continuous body of wall newly, next boring if there is no, is then continued in gap between the body of wall and whether have unstability or permeable situation; If exist, drilling through several peep holes near this hole about 20 centimetres again, confirm whether to exist really unstability or permeable situation, do not exist, then continue next boring, as finding that still the place ahead adds solid and loses steady or a large amount of permeable then stopping to cut, and inject polyurethane, penetrating passage is carried out shutoff by peep hole.After the pending safety, cut the portal concrete again.The character of hole soil sampling determines that detailed portal cuts step according to the observation.Space enclosing structure the place ahead is a concrete continuous wall, and therefore enough stability and anti-water permeable ability are arranged.
(3), segmentation cuts the concrete and the reinforcing bar of portal, replaces former diaphragm wall with plain concrete simultaneously; Cutting three of time-divisions divides from the bottom up and carries out for three times, cuts highly to be 2m at every turn.At first cut the topping of portal space enclosing structure; the first placing of reinforcement net that exposes space enclosing structure; hang out after manually diaphragm wall first placing of reinforcement being cut by undercut; the reinforcing bar cut coverage is greater than more than the cutterhead scope 5cm; cut concrete between diaphragm wall first row and second placing of reinforcement with the big gun machine then; cutting thickness is 90cm; remaining 30cm manually cuts; until exposing second layer steel mesh reinforcement; cut a hole the part that broken second layer reinforcing bar contacts with the nexine concrete; cutting off the second layer steel mesh reinforcement that spills part manually pulls out then; and the plain concrete of timely backfill C15; need in the plain concrete to add an amount of early strength admixture, Using such method is cut a hole complete portal from the bottom up always and is excised second layer reinforcing bar.Reinforcing bar wants scrutiny to have after having cut off does not have remaining steel bar end, stuck cutterhead when preventing that the shield structure from appearing.After portal cuts and finishes, carry out land clearing immediately, to guarantee the shield structure safety of appearing.
(4), the shield machine receiving system is installed, and apply pre-applied force:
1), main part connects
1., before beginning that steel bushing is installed, at first determine well head shield body center line at base plate of foundation pit, the installation site of steel bushing just makes the steel bushing that gets off of hanging oneself from ground make every effort to the disposable position that is put into, move left and right again.
2. hang down the lower semisection of first segment steel bushing, make the center of steel bushing and determine good well head shield body central lines in advance, flange place at steel bushing the right and left of lower semisection puts the thick rubber gasket of 6mm well, with second the joint the Lower Half connection procedure in want the consistent of attention level position and lengthwise position, guarantee that the bolt hole contraposition is accurate, and connect fastening with the high-strength bolt of M27.
3. after Lower Half being connected, again the 1st joint first half is hung and go into the well and connect, and then transition connecting plate and the 1st is saved steel bushing dock.Saving upward with the 2nd, 3 successively, half block hangs down and connects.Each connecting bolt is fastening.
2), the connection of rear end cap
Rear end cap is made up of ellipsoid lid and back shroud two parts, should connect these two parts to hang on the ground when rear end cap is installed again and go into the well, and is fastened on the steel bushing rear flange with M27 bolt (8.8 grades) after adding the thick rubber tile of 6mm between back shroud and ellipsoid cover.
Rear end cap is connected oval deck on the ground to hang down after fastening with the 3rd joint adpting flange again and is connected with back shroud.
3), steel bushing jacking and translation
1. default 4 the jacking brackets of every joint steel bushing Lower Half, can adopt 12 20t mechanic jacks, three sections steel bushings of jack-up simultaneously, having enough spaces to allow the people to dig into bottom up to the steel bushing flange tights a bolt, pad six location points in this space with chock or shaped steel, behind the connecting bolt to be tightened, remove chock or shaped steel again, slowly also unclamp jack synchronously, put down steel bushing.
2. the steel bushing that will connect is to the portal position translation.Utilize 2 60t hydraulic jack to withstand on the platform plate of base plate of foundation pit on one side, another side withstands on the plan-position of rear-end plate, with the steel bushing that connected along the tunnel center line to the translation of portal direction, join until transition connecting plate and portal ring flat-plate.And keep tunnel center line and steel bushing center line not to depart from.Through the measurement group to the center line repetition measurement, confirm errorless after, portal ring flat-plate and transition connecting plate are welded.
2. the transition connecting plate of steel bushing and portal ring flat-plate is connected.
The transition connecting plate of steel bushing is with after the portal ring flat-plate contacts, check whether two planes all can connect, because the situation that being out of shape may appear in pre-buried process in the portal ring flat-plate or deviations from planarity is bigger, so the situation that some place of transition connecting plate can't be closely connected with the portal ring flat-plate might occur, at this moment just need to fill in these gaps steel plates and with the rebound firm welding, the space must be blocked as much as possible.After definite portal ring flat-plate and rebound are all closely connected with the rebound full weld on the portal ring flat-plate.
4), reaction frame and support are installed
1. reaction frame is installed:
Reaction frame is close to the steel bushing bonnet, the hat ball portion does not contact with reaction frame, and its during with the shield machine closed origin the maximum difference of reaction frame be: it is not directly to contact transmission power with the surface plate of rear end cap, but by inside and outside 2 clamping screw (totally 128) the transmission power (can guarantee that like this reaction frame can both hold out against with rear end cap by the length of adjusting each screw rod better everywhere, eliminate and pasted the influence that does not tightly cause discontinuity between the plane) of arranging M30.
When reaction frame is installed, at first should in foundation ditch, locate, then according to the absolute altitude at received well base plate absolute altitude and portal center, suitably adjust the absolute altitude position, center of reaction frame, on ground the footing finishing of reaction frame is finished, and be mounted to integral body, hang down reaction frame installation in place then.
The support of reaction frame: the next uniform 4 10 cun steel pipes and hole body of wall hold out against on the reaction frame, and the uniform three 10 cun steel pipes of a side and the structure side wall that wherein can be supported on side wall hold out against, and opposite side is done bearing diagonal with two diameter 500mm steel pipes.
After the reaction frame diagonal brace installs, need carry out the adjustment of hold-down bolt.After installing reaction frame, tighten each hold-down bolt respectively, adopt the diagonal angle to tighten when tightening respectively, guarantee the evenly stressed of bonnet.The thrust of every bolt is 54000N (pre-counterforce that amounts to reaction frame is about 700T power), tightens the back and pins with locking nut, can guarantee that like this steel bushing portal ring flat-plate place connecting bolt when hydraulic pressure is arranged does not stress.
2. the installation of cross binding
After steel bushing installed, inspection was promptly installed cross binding after confirming.Cross binding adopts 125H shaped steel to be supported on the foundation ditch sidewall structure, and an end that is supported on side wall will add the steel plate capping, guarantees the contact area of support and side wall.The every limit of steel bushing is provided with 6 road cross binding altogether, and 1600mm arranges at interval, and the vertical requirement for height is supported on apart from 500mm place, steel bushing carriage bottom.Reaction frame also will be installed cross binding in addition, totally four supports up and down, and upper support avoids reaction frame lateral displacement to occur on negative three layer construction.
(5), in the steel bushing of receiving system, carry out filler to requiring height;
After inspection finished, filler in steel bushing, described filler were the tabia of a sand material and a part, suitably add water in the process of filling, and guarantee the closely knit of sand.Carry out filler respectively from three stuffing holes, until filling up.Add water to then and be full of steel bushing fully.
For the sand material is delivered in the steel bushing, need draw a conveyance conduit from ground to steel bushing, adopt one 10 cun pipeline to connect, ground is provided with a funnel, and the sand material directly is delivered in the steel bushing from funnel.If the sand material is carried when smooth and easy inadequately, can adopt the bath mode in the filler process, sand is swept away, water enters in the steel bushing with after sand mixes, and can also play the effect that sand is closely knit.
For the filler in the steel bushing is closely knit evenly, to fill respectively at three stuffing holes in the filler process, guarantee distributed uniform, filling process carries out stage by stage, send someone to observe at stuffing hole, need carry out smooth closely knitly when being filled to certain altitude, continue filler again until being full of whole steel bushing fully after smooth.
(6), steel bushing is carried out voltage-withstand test:
1. leak detection
In steel bushing, add water from water inlet, to topped up with water, check pressure, if pressure can reach 3bar.Then stop to add water, and keep pressure stability.As reaching 3bar by hydraulic pressure, then water pipe is untied, utilize the air compressor machine aerating, in steel bushing, add air pressure, till pressure reaches 3bar, each coupling part is checked, comprised that portal junction plate, steel bushing hoop and the vertical junction of link position, rear-end plate have or not to leak, check that each position while welding that reaction frame supports has or not the sealing-off situation.
2. steel bushing displacement detecting
Various measurement apparatus will be installed in the shield machine assembling process, mainly are that the central part of tested steel socket end cover plate has or not distortion, and the displacement of steel bushing etc.
Trying the water, before the applied voltage test, foil gauge being installed in the subregion, position that steel bushing is connected with the portal ring flat-plate, on the steel bushing surface dial gage is installed, range can be controlled deflection or displacement precision at 0.01mm at 0～10mm.In the applied voltage test process,, must carry out release immediately, analyze reason and take solution in case find that strain exceeds standard or displacement is excessive.According to designing and calculating, the strictest position of displacement control is the link position of portal ring flat-plate and steel bushing, and this position allows deflection less.Mode is one on the other taked in the installation site shown in Figure 23 and 24, two positions are monitored, and allows deflection between 0.5～1mm, in case exceed this scope, stop pressurization immediately, checks that each link position has or not distortion or collapses the weldering situation.The another location is the centre dot position of bonnet spheroid, and the maximum that herein is stressed must its deflection of monitoring.As shown in figure 25, be the displacement of monitoring ellipsoid lid central point, allow deflection bigger herein, maximum permission deflection is 5mm, as long as deflection is no more than 5mm, just can satisfy requirement of strength.
(7), the shield machine tunneling construction, enter or break away from portal up to the shield machine shield tail;
1. arrive to entering steel bushing section boring parameter setting table
|The cutterhead position
||The cutterhead revolution
||Cutter disc torque
||Air pressure is set
||The situation of slagging tap
||Driving ring number
|1.2 rice diaphragm wall
||Plain concrete C20
||The concrete slag
|2.0 rice portal
||The M75 cement mortar
||The mortar piece
|9.6 rice steel bushing
Annotate: when shield machine was shifted 610 and 616 rings onto, shield machine speed was pressed 3mm/min.
2. circulation control
Flow-control is at 500～600m
3Between/the h, so that take dregs smoothly out of.Reduce the contrary operation of dashing as far as possible, alleviate the sleeve inner pressure oscillation, in time understand the situation of slagging tap with the mud conditioning operating personnel.
1, the broken cement mortar that holes of cutterhead, when promptly tunneling 608 rings, 609 rings, the pressure of circulation, ground water pressure communicate with steel bushing hydraulic pressure, and pressure has fluctuation, observes native storehouse pressure and changes, and place, notice Luo Xi station checks portal sealing situation.
2, because of diaphragm wall, cement mortar, backfill sand all are the artificial constructions of filling out of mending, do not get rid of foreign matter is arranged in the middle of (as woven bag etc.) fall into, when these foreign matters of cutting, fall into the circulation mud pipe, cause plugging.
3. slip casting control
1, injected hole: 608 rings～614 endless tube sheets, totally 7 endless tube sheets require every ring to punch 4 or 5 injected holes in advance.K piece section of jurisdiction agree to select Lower Half positions such as 4 points, to the greatest extent at 8.The section of jurisdiction first half more is used for section of jurisdiction benefit slurry in the hole like this.
2, grouting amount: every ring is by 180% control of theoretical grouting amount, about 7～8m
3, the about 7bar of grouting pressure.Single tube uses, and grouting pump is transferred to 6 grades, water glass flow 4m
3/ min.What leak as the shield tail is the biliquid slurry, can suitably stop, and changes the position, hole.
4. annotate polyamine fat shutoff control
1, position: tunnel 610 rings, jack stroke 1200mm place shuts down, and VMT shows 7+460.32.At this moment, middle body greasing is apart from plain concrete wall limit 100mm, and body selects poly-peace fat hole (at least 3) diverse location to inject poly-peace fat in shield machine.
2, injection rate: the amount control that every hole is 2 barrels.Form defence line, the domain 1 road, in the outside of diaphragm wall.
5. attitude of shield machine control
1, monitoring tool: tunnel manual measurement: 608～614 interannulars, attitude of shield machine carry out one survey of 2 rings, in time monitored data, feedback Central Control Room.
VMT measures: guarantee normal use, have unusually then and shut down, back to be repaired driving.
2, operation control: choose the propelling jack, note oil pressure control, the attitude that comes back slightly by the shield machine control of advancing.Jack is selected to make progress a little, to control left, and minimum oil pressure is not less than 30bar, and pressure differential is the highest can not to surpass 100bar, avoids excessive the squeezing of pressure differential to break the section of jurisdiction.To (point-20 after the level of point-20. before the level, Tunnel Design center; Point before vertical+10. vertical back point 0).
(8), the steel bushing to receiving system carries out release, disassembles
1., the first half steel bushing is disassembled
After shield machine arrives in the steel bushing smoothly, tear steel bushing open and will replenish slip casting to the section of jurisdiction in the structure earlier before, after affirmation slip casting is closely knit, can disassemble.
1, steel bushing release
Shield machine at first carries out the section of jurisdiction slip casting of portal position after entering in the steel bushing fully, mends and carries out bringing down stocks of circulation system after slurry is finished, and cutterhead and Tu Cang is repeatedly cleaned, to reduce the cleaning work when tearing shield machine open.Bring down stocks after the end, circulation system soil storehouse pressure is slowly reduced, note in the step-down process observing liquid level change in the gas storehouse, whether leak to judge the portal place.As Non Apparent Abnormality, treat that native storehouse pressure is reduced to normal pressure after, open the discharge pipe in the steel bushing outside, with water emptying in the steel bushing, close upper ball valve then, wait for about two hours after, once more to carrying out draining in the steel bushing, and the mensuration displacement, as no abnormal, illustrate that then the portal place leaks not quite, can disassemble, excessive as the water yield, must continue to mend slurry to the portal section of jurisdiction, until no longer leaking.
2, pulling down steel supports
After the release, at first to carry out the unloading of reaction frame pre-counterforce in the steel bushing, the counter-force screw rod is unclamped, throw off, tear the reaction frame steel behind the reaction frame pre-counterforce complete discharge again open and support until screw rod push rod and rear-end plate.Hanging steel with Chain block earlier supports, utilize burning torch to sever former support welding position then, after severing fully, utilize jack to withstand steel and support, remove former pre-applied force after, wedge type block is taken away, slowly discharge the top power of jack, after the top power for the treatment of jack discharged fully, steel supported to be under the complete disengaged position steel supported and slowly pulls down, and 11 steel support successively and remove altogether.
3, tear reaction frame and diagonal brace open
Utilize burning torch that the support of reaction frame is severed, when cutting diagonal brace, will hang diagonal brace and keep balance, cut the junction with reaction frame earlier, cut the junction with built-in fitting again, can hang out after weld seam cuts off and finishes with Chain block.Reaction frame will hang with loop wheel machine in cutting off the process of support, and with going up certain lifting force, keeps reaction frame steady, prevents that reaction frame falls down under the situation that does not have support.
4, pull down rear end cap
After reaction frame hung out, rear-end plate can hang out.Rear end cap adopts the whole method that hangs out, and can integral body hang out after pulling down connecting bolt, hang out must guarantee in the process rear end cap steadily, can not collide.The hat spherical cap prevents to bump against in the process of hanging out and causes distortion on the structure.
5, pull down the steel bushing first half
The steel bushing first half adopts flange to be connected, every upper semi-circle has 66 M27 high-strength bolts with every limit, lower half circle junction and links to each other, every with every between semi-circular portions have 60 high-strength bolts and link to each other, after every connecting bolt untied, the 150T loop wheel machine hangs hanger, confirms that whole bolts are disassembled the first half to be begun to hang out one by one after finishing.The steel bushing main part is numbered 1,2,3 along the tunnel piercing direction, and every joint steel bushing is divided into up and down two semi-rings, thus six semi-rings are followed successively by on 1, on 1 time, 2, on 2 times, 3,3 times.
After the steel bushing first half broken, need immediately tissue to transport, reduce the place holding time.After the steel bushing first half had been torn open, the first half of shield machine promptly exposed, and possessed the condition of disassembling shield machine after cleaning out.
2. the steel bushing Lower Half is disassembled
After shield machine is disassembled fully and finished and hangs out, possesses the condition that steel bushing the latter half is disassembled.
1, cutting off the carriage bottom transverse supports
After shield machine hung out and finishes, the cross binding of carriage both sides can be cut off fully, and preparation steel bushing the latter half is disassembled and hung out.
2, sever and being connected of portal ring flat-plate
Because the adpting flange and the portal ring flat-plate of steel bushing are to weld together by transition connecting plate, thus treat shield machine disassemble finish after, directly utilize burning torch that the position of transition connecting plate is severed.The portal ring flat-plate is with after steel bushing separates, and the method that can adopt integral body to hang out hangs out steel bushing Lower Half integral body.
3, integral body hangs out steel bushing the latter half
Four hangers of welding on the steel bushing inwall, each hanger load-bearing are more than 20T, and the about 65T of steel bushing Lower Half gross weight after employing integral body hangs out, can possess the condition of disassembling on ground, helps shortening the holding time of received well.
The present invention is a kind of safe, economic, efficient, succinct shield machine closed origin and arrival pattern, change the uncontrollable factor in shield launching and the arrival process into controllable factor, greatly reduce the risk in the work progress, for controlling ground settlement preferably provides the shield machine closed origin of effective guarantee and the job practices of arrival.