CN210105867U

CN210105867U - Shield tunnel end frozen soil wall and ground are wall jointly reinforced structure

Info

Publication number: CN210105867U
Application number: CN201920973884.7U
Authority: CN
Inventors: 胡俊; 巢达; 刘勇
Original assignee: Hainan University
Current assignee: Hainan University
Priority date: 2019-06-26
Filing date: 2019-06-26
Publication date: 2020-02-21
Anticipated expiration: 2029-06-26

Abstract

The utility model discloses a shield tunnel end frozen soil wall and ground are wall jointly reinforced structure, unite reinforced structure including frozen soil wall and ground are wall even, and wherein frozen soil wall sets up in the position department near envelope, and ground is wall even and is established at the rear portion of frozen soil wall. The construction method comprises the following steps: firstly, constructing the diaphragm wall, wherein the construction process comprises the following steps: measuring and paying off → making a guide wall → mixing slurry → grooving and bottom clearing replacement of a diaphragm wall → processing and hanging of a glass fiber reinforcement cage or a bamboo reinforcement cage → concrete pouring → joint construction → top drawing of a joint pipe → complete construction; step two, construction of the frozen soil wall: the construction of the frozen soil wall is that before shield tunneling, a water-containing stratum in the working well end area is frozen into a closed waterproof curtain to form the frozen soil wall by an artificial refrigeration method, and the beneficial effects are that: can properly reinforce the stratum at the end of the water-rich sand layer in the coastal areas, the coastal areas and the like.

Description

Shield tunnel end frozen soil wall and ground are wall jointly reinforced structure

Technical Field

The utility model relates to a joint reinforced structure, in particular to shield tunnel end frozen soil wall and ground are reinforced structure jointly even wall.

Background

At present, the reinforcement of the end of the shield tunnel is a key link in the shield method construction, and has great engineering construction risks. When the shield enters and exits the tunnel, the underground diaphragm wall of the tunnel portal area is broken first, and all the steel bars are cut. The time required for breaking the tunnel portal is very tight, and the construction difficulty is high. After the tunnel portal is broken, the requirements on the strength and the sealing performance of the reinforcing body are high, and when the reinforcing effect is not good, the phenomena of mud gushing and sand gushing and surface subsidence of a shield and a tunnel portal gap are easy to occur during the tunnel portal breaking, so that the safety of nearby underground pipelines and buildings is endangered. In order to prevent the phenomenon, a reasonable shield tunnel end stratum reinforcing treatment scheme must be selected to meet the requirements of strength and impermeability.

The common reinforcing methods of the shield tunnel end include a deep stirring method, a high-pressure jet grouting method, an SMW (soil mixing wall) construction method, an artificial freezing method, a grouting method, a plain concrete cast-in-place pile method, a dewatering method and the like. The soil body can be reinforced by adopting a reinforcing means combining one or more construction methods. The reinforcing mode is selected according to conditions such as engineering geological conditions, underground water level, structure burial depth, shield machine type and diameter, operation environment and the like, and factors such as safety, construction convenience, economy, construction period and the like are considered.

In coastal areas, along rivers, along lakes and the like, particularly when the stratum at the end of the shield tunnel is a water-rich sand layer, the engineering requirements are difficult to meet by adopting the conventional chemical reinforcement means, and the phenomena of water leakage and sand leakage are often found after the hole exploration is carried out chemically. The reasons for this are: the pressure-bearing water level of the end head reinforcing area is high, cement slurry is easy to lose after penetrating into a sand layer in the construction process, the larger the depth is, the stronger the permeability is, the more serious the cement slurry loss is, and the sand layer cannot be effectively consolidated; and secondly, most of the construction period is in the precipitation period, the water level of the working well is greatly reduced, and the relief well of the working well is basically as deep as the underground diaphragm wall, so that the influence on the groundwater outside the pit is large. After precipitation, a large water head difference is formed between the working well and the outside of the pit, and cement paste flows along with underground water seriously due to strong water permeability of a sand layer, so that cement soil in the sand layer at the lower part of the stirring pile, which is partially close to the underground diaphragm wall, is loosened and is not effectively solidified. At the moment, in order to improve the strength of soil body at the end of the shield tunnel, fully stop water and ensure the safety of the shield in and out of the tunnel, the technical problem to be solved is how to select a stratum reinforcing mode at the end of the water-sand-rich layer.

Disclosure of Invention

The utility model aims at improving shield tunnel end soil body intensity and abundant stagnant water, guarantee shield structure business turn over hole safety, how to select the stratum reinforcing mode and a shield tunnel end frozen earth wall and ground even wall joint reinforced structure who provides being rich in water sand layer end.

The utility model provides a shield tunnel end frozen soil wall links reinforced structure with ground even wall and links the wall including frozen soil wall and ground, and wherein frozen soil wall sets up in the position department near retaining structure, and ground is linked the wall and is established at the rear portion of frozen soil wall.

The frozen soil wall is a vertical frozen soil wall, the diameter of freezing pipes in the frozen soil wall is 127mm, the freezing pipes are arranged in two rows, the flowers are arranged, the pipe spacing is 800mm, and the row spacing is 800 mm; the freezing pipe close to the enclosure structure is 400mm away from the side of the groove wall, the length of the plane where the freezing pipe is arranged is 3m of the two sides of the shield tunnel, the freezing pipe is partially frozen in the length from 3m of the vault of the shield tunnel to 3m of the vault, or is frozen in the full length in the length from the ground to 3m of the vault, the freezing pipe is made of a seamless low-carbon steel pipe or a PVC plastic pipe or a PPR plastic pipe or an ABS plastic pipe or a PE plastic pipe, and the section of the freezing pipe is circular, I-shaped, X-shaped, T-shaped or Y-shaped.

The stressed framework in the underground diaphragm wall is a glass fiber reinforcement cage or a bamboo reinforcement cage, the wall body of the underground diaphragm wall is formed by pouring cement concrete, the label is not lower than C30, the protective layer of the glass fiber reinforcement cage or the bamboo reinforcement cage is not less than 70mm, the thickness of the wall body of the underground diaphragm wall is 800mm, the plane length of the underground diaphragm wall is 3m on two sides of the shield tunnel, the underground diaphragm wall is locally poured in the depth direction length from 3m of the vault of the shield tunnel to 3m of the arch bottom, or the full-length pouring is carried out in the depth direction length from the ground to 3m of the arch bottom.

The utility model provides a shield tunnel end frozen soil wall and ground are wall joint reinforced structure's construction method, its method is as follows:

firstly, constructing the diaphragm wall, wherein the construction process comprises the following steps:

measuring and paying off → making a guide wall → mixing slurry → grooving and bottom clearing replacement of a diaphragm wall → processing and hanging of a glass fiber reinforcement cage or a bamboo reinforcement cage → concrete pouring → joint construction → top drawing of a joint pipe → complete construction;

step two, construction of the frozen soil wall: the construction of the frozen soil wall is that before the shield tunneling, a water-containing stratum in the working well end area is frozen into a closed waterproof curtain to form the frozen soil wall by using an artificial refrigeration method, the curtain is used for resisting ground pressure, water pressure and isolating underground water, the safety of the shield tunneling machine in and out of a hole is ensured, firstly, the drilling construction of a freezing hole is carried out, meanwhile, the installation construction of a freezing station is carried out, after the freezing hole construction is finished, the freezing hole series pipeline and the heat preservation work are carried out, then, the freezing is actively frozen, after the freezing is determined to meet the removal condition of the portal through observation and calculation of a temperature measuring hole, the wall of the hole opening is broken, the shield tunneling machine is forcedly unfrozen before entering and exiting the hole, meanwhile, the vertical freezing pipe is pulled out to the upper part of the shield tunneling machine to be kept frozen, after the shield tunneling.

The concrete construction steps of the diaphragm wall in the first step are as follows:

step one, measurement and paying-off:

measuring the axis control piles of the diaphragm wall according to the axis control piles provided by a construction party, wherein the control piles adopt protection piles, the elevation is introduced into a site, a closed loop measurement method is adopted, level points in the site are set, the elevation of the diaphragm wall is controlled according to the level points, and an instrument which is subjected to inspection and correction is used for measurement;

the axis is determined by using a J2 theodolite and a DS3 leveling instrument for measuring a leveling point;

pile positions and mark requirements set in engineering measurement are totally packaged, managed and retested, and pile protection work is done;

the theodolite, the level and the control quality detection equipment used for measuring and positioning are qualified through identification, and the measuring instrument in the service cycle carries out measurement detection control according to a secondary measurement standard;

step two, manufacturing a guide wall:

before the deep groove is excavated, excavating a guide channel along the longitudinal axis of the design of the diaphragm wall, pouring reinforced concrete guide walls on two sides, and manufacturing the guide walls to extend outwards by 200mm at corners so as to straighten the corners during excavating the groove and clean the guide walls;

the method comprises the following steps of performing lofting work and checking on the axis of a guide wall, combining mechanical work and manual work for excavating soil, strictly disturbing original soil, paving a cushion layer, paying attention to a 3cm chamfer angle, erecting a template on an inner mold, replacing the outer mold with soil, uniformly casting and tamping two sides during concrete casting and tamping, vibrating and compacting by a vibrator, removing the mold after the concrete reaches 70% strength, timely supporting between walls by 100 multiplied by 100mm square timber after removing the mold, wherein the supporting interval is 2m, the upper and lower sides are two sides, heavy machinery cannot work and walk near the guide wall during maintenance, the guide wall is prevented from being extruded into a groove, and the strength grade of the concrete of the guide wall is C20;

the center lines of the guide wall and the underground connecting wall are required to be consistent, and the vertical surface is required to be vertical;

step three, slurry preparation:

1) and preparing slurry: in the process of forming grooves on the diaphragm wall, slurry is uninterruptedly supplied to the grooves in order to keep the stability of the soil wall of the excavated groove, and the slurry mixing ratio is as follows: 8-12% of bentonite; CMC/0.8-1.2%; na (Na)₂CO₃1.5 to 4 percent; the slurry is pumped into a slurry storage tank for storage after being uniformly stirred in a stirring tank, new slurry can be used only after being stabilized for 24 hours, the specific mixing proportion is adjusted according to the actual construction condition, the performance of the newly-mixed slurry is tested every 24 hours, the performance is controlled to be adjusted at any time, and the slurry is recycled to be detected in each tank;

2) and slurry storage: storing the slurry by adopting a sheet iron box;

3) and slurry circulation: the slurry circulation adopts a four-inch pump to convey and recover, a slurry circulation pipeline is formed by a slurry pump and a hose, the performance of the recovered slurry is detected, and the recovered slurry is returned to a slurry storage tank by a pump with excellent indexes until the next tank section is reused;

4) separating and purifying the slurry: in the process of diaphragm wall construction, mud can be polluted and deteriorated, and after the mud is used for one cycle, the mud needs to be separated and purified so as to improve the reutilization rate of the mud;

5) adjusting the slurry: after the recovered pulp is precipitated in the pulp returning pool, the part with still good indexes is directly pumped back to the pulp storage pool, and the part with changed indexes is adjusted in the stirring pool and then pumped back to the pulp storage pool;

6) and treating waste slurry: the waste slurry refers to degraded slurry which is in contact with concrete and is polluted by cement to deteriorate in the concrete pouring process and over-standard slurry which is repeatedly used for many times, exceeds the standard in viscosity and specific gravity but is difficult to separate and purify so as to reduce indexes of the degraded slurry, the waste slurry is pumped into a waste slurry pool by a pump for temporary storage, and then the waste slurry is transported outside a vehicle for abandonment;

7) and detecting the slurry: the method comprises the steps of mixing new slurry, carrying out slurry performance detection, using the slurry after the new slurry is qualified, carrying out spot check on slurry performance indexes in the tank forming process, if the slurry performance indexes do not meet requirements, adjusting the slurry performance indexes to ensure the tank forming quality, carrying out slurry performance detection after bottom cleaning is finished, carrying out slurry replacement treatment if the slurry performance indexes are unqualified, carrying out slurry recovery detection, and carrying out waste slurry treatment if the performance indexes are seriously deteriorated, and carrying out transport outside a vehicle by using waste slurry;

step four, grooving and bottom cleaning replacement of the underground diaphragm wall:

1) forming grooves on the diaphragm wall:

before grooving, checking and accepting the guide wall, and recording; marking a groove section on the guide wall, sealing the formed groove section and cleaning the groove section, and sealing the plug to prevent slurry from losing; the grooving sequence of the groove sections is according to the grooving mode of the connecting breadth, two joint pipes are arranged in a first slotted hole, the joint pipes are arranged from a second slotted hole in sequence number, one joint pipe is arranged in the second slotted hole and each slotted hole behind the second slotted hole, when adjacent groove sections are excavated, the concrete strength is required, and if the concrete strength is not required, the number of first open breadths is increased;

positioning a trenching machine: positioning at the minimum angle on the premise of ensuring stability; after a trenching machine is positioned, slurry is put in, trenching is started, the liquid level of the slurry is always kept, the liquid level is not more than 300mm from the top of a guide wall, the slurry is uniformly excavated at a low speed, the verticality and the skewness are controlled within an allowable deviation range, the slurry cannot be washed and grabbed in the trenching process, the head grabbing state and the trench wall state are monitored at any time by adopting a theodolite or a string hammer, the verticality of a trench section is ensured to be within 1/300, and the depth of the slurry is measured by a measuring rope at any time in the trenching process so as to avoid overbreak;

during construction, when the grab bucket enters and exits the wall guide port during groove digging operation, the grab bucket needs to be lifted slowly to prevent mud from lifting waves to influence the stability of a soil layer below the leading wall of the diaphragm wall, when the grab bucket ascends, qualified wall protection mud is continuously supplemented into the groove, the ascending speed of the grab bucket is adaptive to the mud supplementing speed, the liquid level of the mud is kept within 30cm below the top surface of the wall guide, and the phenomenon of hole collapse caused by the fact that the mud in the groove descends too fast is avoided;

in the grooving process, the crane must be positioned on the flat and compact ground, the stability is good, the crane boom cannot collide with other objects when being rotated, a steel wire rope for suspending a machine tool must be in a vertical state on the center line of the guide wall and cannot be loosened, and the grooving machine leaves the operation groove section when the grooving of the unit groove section is finished or the operation is suspended;

2) and bottom clearing replacement:

bottom cleaning is to clean sediment at the bottom of a groove after the groove digging is finished, so that the thickness of the sediment is not more than the standard requirement, and to clean mud skin and sediment on a concrete joint surface of a wall section in a first period so as to meet the standard requirement, the specific method is to form the groove to a preset depth, reserve 200mm, start wall brushing, eliminate the deposited mud between the formed wall ends, perform ultrasonic testing after the wall brushing is finished, perform hole cleaning and bottom cleaning by using a grab bucket of a grooving machine after the testing is finished, and ensure that the specific gravity of the mud at the bottom of the hole and the sediment meet the design requirements when the depth is reached, the thickness of the sediment at the bottom of the wall is less than 100mm, and the specific gravity of;

step five, processing and hanging the glass fiber reinforcement cage or the bamboo reinforcement cage:

firstly, processing and hoisting a glass fiber reinforcement cage:

the glass fiber reinforcement cage in the underground diaphragm wall is divided into an upper section and a lower section which are respectively lifted into a groove and then spliced into a whole frame at the notch for lifting operation;

1) reinforcing and binding glass fiber ribs:

glass fiber reinforcements are used in the propulsion range of the underground diaphragm wall shield, so that a glass fiber reinforcement cage belongs to a flexible structure at the shield ring, the glass fiber reinforcement cage is required to be reinforced before hoisting, a longitudinal through long steel bar truss is arranged as a reinforcing measure, and the upper layer glass fiber reinforcement and the lower layer glass fiber reinforcement are fixed by steel pipes;

① measuring and enlarging sample, accurately releasing the shield cutting range on the glass fiber reinforcement cage processing platform, setting an obvious mark, and placing a lower reinforced steel pipe;

② laying lower glass fiber reinforcement according to design drawing, and binding the glass fiber reinforcement with 2.0mm galvanized iron wire;

③ installing longitudinal steel bar trusses;

④ laying and binding the upper glass fiber ribs according to the design drawing;

⑤ installing a steel wire rope clip between the glass fiber reinforced bar and the truss steel bar, and checking with a torque wrench, wherein the torque is not less than 50 NM;

⑥, installing and inspecting the reinforced steel truss;

2) the hoisting point of the glass fiber reinforcement cage is set as follows:

in order to ensure the balance of lifting, eight lifting points are arranged on the lifting surface of the glass fiber reinforcement cage according to the stress characteristics, and the positions of the lifting points are selected on the truss main ribs; two groups of hanging ribs are symmetrically and evenly arranged at the top end of the glass fiber reinforcement cage, the hanging ribs are welded with the steel truss, the welding length reaches 10d, and d is the diameter of the steel bar;

the selection of the lifting point position needs to consider the weight difference between the glass fiber reinforcement and the reinforcing steel bar, and after accurate calculation and trial lifting confirmation, formal lifting can be carried out;

3) hoisting the glass fiber reinforcement cage:

the method comprises the following steps that an eight-point hoisting method is adopted for hoisting the upper section of the glass fiber reinforcement cage, two crawler cranes are selected for hoisting, wherein 100t of the crawler cranes are used as a main crane, 50t of the crawler cranes are used as auxiliary cranes, the glass fiber reinforcement cage is horizontally hoisted by the double cranes, then the main crane and the auxiliary cranes are lifted and placed, the glass fiber reinforcement cage is vertically hoisted to be straight, and the main crane transports the glass fiber reinforcement cage to the dug notch and directly places the glass fiber reinforcement cage in place; the lower glass fiber reinforcement cage adopts a six-point hoisting method, and two crawler cranes hoist;

4) and installing the glass fiber reinforcement cage in place:

firstly, hoisting a lower section of glass fiber reinforcement cage into a groove, then penetrating a hoisting beam into a temporary suspension ring of the glass fiber reinforcement cage, placing the suspension beam on the top surface of a guide wall, butting the glass fiber reinforcement cage with a notch, and then reinforcing a steel truss and lowering a steel pipe into the groove while removing the glass fiber reinforcement in the whole width range;

after the whole glass fiber reinforcement cage is in place, the deviation between the plane position and the elevation of the positioning of the glass fiber reinforcement cage in the groove is carefully checked, and the hoisting position of the glass fiber reinforcement cage is made to meet the design requirement by adjusting the position and the elevation;

secondly, processing and hanging the bamboo reinforcement cage:

1) and constructing a bamboo reinforcement cage platform:

erecting two bamboo reinforcement cage platforms on site, wherein the platforms are welded by [10 channel steel, the bottom layers of the platforms are paved by plain concrete and are 100mm higher than a hard terrace in the field, the platforms are leveled by a leveling instrument, and the bamboo reinforcement cage platforms are lofted by a theodolite so as to ensure that four corners of the bamboo reinforcement cage platforms are right angles;

2) and forming bamboo ribs and bamboo splints:

arranging a bamboo reinforcement processing shed specially used for forming bamboo reinforcements and bamboo battens on a construction site, wherein the bamboo reinforcements and the bamboo battens to be formed are processed and formed by a specially-assigned person and are stacked in a classified manner so as to facilitate the processing work of the bamboo reinforcement cage;

3) and manufacturing a grouting pipe:

the grouting pipes are phi 33.5 multiplied by 3.25 steel pipes, tapping threads are connected by a threading machine, two grouting pipes of each groove section are fixed on the bamboo reinforcement cage, and the tail parts of the grouting pipes are wrapped by rubber;

4) and manufacturing the bamboo reinforcement cage:

paving the soil-facing bamboo rib net sheets, firmly binding the soil-facing bamboo rib net sheets, and binding the moso bamboos of the soil-facing bamboo rib net sheets; manufacturing a truss, and arranging the truss on the soil facing surface reinforcing mesh and binding; binding moso bamboo and bamboo rib net sheets on the surface facing the pits; binding a sealing rib and a positioning block; binding a hanging bar;

5) and controlling the positions of the bamboo reinforcement cage and the embedded reinforcements:

the bamboo reinforcement cage top elevation control adopts a level gauge, after grooving is finished, elevations of four points are respectively measured on a guide wall according to the positions of hanging reinforcements, then the lengths of the hanging reinforcements are determined to ensure the bamboo reinforcement cage top elevation, the embedded reinforcements are positioned by a steel tape measure by taking the cage top elevation as a datum point, and then the embedded reinforcements are placed;

the horizontal position control needs to draw specific positions on the positioning bamboo ribs according to the design positions and the intervals, and then the embedded ribs are placed;

the embedded ribs are accurate in placement position and firm in binding, and the anchoring length of the embedded ribs is required to meet the requirements of design and construction specifications;

6) the bamboo reinforcement cage is required to be as follows:

because the diameters of the moso bamboos are not uniform up and down, the middle parts of the whole bamboos are bound to the position with the largest stress on the wall body in the binding process of the bamboo reinforcement cage, so that the stability of the wall body is ensured;

in construction, the bamboo is in a hollow structure and the diameter of the bamboo is large, so that the buoyancy of the bamboo is far larger than that of the reinforcing steel bar, the bamboo is difficult to be directly inserted in the mud inserting process, and the buoyancy is reduced by adding a heavy object to the lower part of the bamboo reinforcement cage or drilling the bamboo body, so that the bamboo reinforcement cage is smoothly installed in place;

step six, concrete pouring:

the design label of the diaphragm wall concrete is C30 underwater concrete, the impermeability is S8, the slump of the concrete is 200 +/-20 mm, the diffusivity is 340 plus-380 mm, the concrete is transported to the site by a mixer truck, the used conduit for pouring the concrete is phi 250, the waterproof bolt adopts a plastic ball, each groove section adopts two conduits for pouring, the height difference of the poured concrete from the bottom of the groove section for the first time is not less than 30cm, and the concrete truck directly pours the firm groove conduit during pouring;

after the concrete is poured to the designed height, the super pouring concrete surface is 0.3-0.5m higher than the designed height, when the concrete is poured, the notch is provided with a cover plate, the concrete surface is ensured to uniformly rise in the pouring process, the height difference of the highest part to the lowest part is not more than 30cm, the concrete pouring is finished at one step without interruption, and the rising speed of the concrete surface is ensured to be not less than 2 m/h;

the buried depth of the guide pipe is kept at 2-6m, the height of the concrete surface is measured at any time when concrete is poured, the number of the concrete surface and the guide pipe is checked, and the emptying is strictly forbidden;

50m per perfusion³After the concrete is made into a group of compression-resistant test blocks, the thickness of said test blocks is more than 50m³Adding a group of anti-seepage test blocks, and making one group of anti-seepage test blocks according to each wall;

step seven, joint construction:

the joint adopts a flexible circular locking pipe joint, the joint pipe is placed at one end of the non-grooved section and is close to the soil wall, the concrete is prevented from being bonded with the soil body of the non-grooved section, the concrete side formwork function is realized, after the concrete is poured, the joint pipe is gradually pulled out, and a circular concrete joint surface is formed at the end of the pouring section;

the joint pipe is placed to the bottom, the verticality deviation of the whole length of each assembled joint meets the requirement, various jacks on the joint box are blocked by wood wedges, clay balls are backfilled on the back side of the joint pipe, and concrete is prevented from moving around the pipe and the joint box;

step eight, jacking and drawing the joint pipe:

the joint pipe is jacked and pulled by a hydraulic jack, and the jacking and pulling device consists of a base, an upper tray, a lower tray, a force bearing cross beam, two 100t plunger type jacks with the stroke of 1.2-1.5m and a matched high-pressure oil pump;

the lifting and pulling time control of the joint pipe is to control the lifting and pulling time of the joint pipe according to the condensation condition of a first concrete pouring test block and the initial setting time of concrete, the first lifting and pulling is controlled within 200-300 mm, the lifting and pulling speed is controlled by referring to the reading of a lifting frame oil pressure gauge or one lifting and pulling time from 15 minutes to 30 minutes, the lifting and pulling height is controlled by the reading of the pressure gauge, and the joint box is pulled out after 6-8 hours after the concrete pouring is finished;

and (3) brushing the wall after the grooving is finished, and brushing the wall of the grooved breadth end of the finished wall by using a steel wire brush on the side surface of the wall brushing device for multiple times by using a 150-ton crane according to the self-made wall brushing device in a joint form so as to brush and remove mud skin, soil and mortar adhered to the joint and prevent the joint from being leaked due to mud clamping.

The concrete construction steps of the second step of the frozen soil wall construction are as follows:

step one, freezing design:

firstly, designing the thickness of a frozen wall:

1) designing the thickness of the freezing curtain by combining engineering characteristics, soil layer conditions and construction site conditions, wherein the thickness of a vertical frozen soil wall close to the working well enclosure structure is 2.0 m;

2) freezing the curtain physical parameters: taking the average temperature of the frozen soil to be-10 ℃, and carrying out indoor test determination on the frozen soil strength index;

3) and the size of the reinforcing body:

transverse width: 3m on two sides of the shield tunnel;

depth: local freezing is carried out in the depth direction length from the vault 3m to the arch bottom 3m of the shield tunnel, or full-length freezing is carried out in the depth direction length from the ground to the arch bottom 3 m;

secondly, arrangement of freezing holes: two rows of freezing holes are arranged, the flower arrangement is carried out, the hole spacing is 800mm, the row spacing is 800mm, and the distance between the vertical freezing holes close to the working well enclosure structure and the groove wall edge is 300mm and 400 mm;

thirdly, arranging temperature measuring holes: the position of the temperature measuring hole is adjusted according to the deviation condition of the drilling hole, and the purpose is mainly to measure the temperature development conditions of different parts in the range of the freezing curtain so as to take corresponding control measures and ensure the construction safety;

step two, designing a refrigerating system:

firstly, parameter selection:

1) the vertical freezing pipe is a seamless low-carbon steel pipe with the diameter of 127mm multiplied by 4.5 mm;

2) when the brine cooling medium is adopted, the temperature of the brine in the outgoing passage in the freezing period is-28 to-30 ℃, and the temperature of the brine in the return passage is-25 to-28 ℃;

3) saline water specific gravity 1.26;

4) the flow of the brine in the freezing pipe is 5m³/h；

5) Freezing pipe heat-dissipating ability: 260Kcal/m².h；

6) And the cold loss coefficient: 1.2;

secondly, calculating the cooling capacity requirement:

and (3) calculating freezing cold quantity demand: q is 1.2 pi.d.H.K

Wherein H is the total length of the freeze;

d-freezing tube diameter;

k-the heat dissipation coefficient of the freezing pipe.

Setting a freezing station, selecting types and quantity of units:

two W-YSLGF600 II type screw refrigerators are selected as freezing stations, and the refrigerating capacity of each unit is 28 multiplied by 10⁴Kcal/h, motor power 220 kw;

fourthly, a brine system:

1) the brine main pipe and the collecting and distributing liquid ring are selected: machining and manufacturing a phi 159 multiplied by 5mm welded pipe;

2) the used salt is calcium chloride crystal with the content of 80 percent;

3) and selecting a brine pump: three IS 150-125-type 315 centrifugal water pumps with the flow rate of 200m are selected³H, motor 30 kw;

fifthly, a clear water system:

1) and the clear water pipe is selected: machining and manufacturing a phi 133 multiplied by 4.5mm welded pipe;

2) selecting 8m³Three clear water tanks;

3) fresh water replenishment amount: 30m³/h；

4) Selecting three IS 150-125-type 315 centrifugal water pumps with flow rate of 200m³H, motor 30 kw;

5) selecting four KST-80 type cooling towers;

sixthly, predicting frozen wall formation: taking the development speed of a freezing curtain to be 25 mm/day, taking the maximum hole spacing of freezing pipes to be 800mm, and then, taking the circle-crossing time to be t₁800/2/25 is 16 days, the freezing wall cross-linking time is 20 days, and the whole active freezing time is more than 30 days.

Step three, drilling construction:

firstly, selecting the type of drilling equipment:

selecting two XP-30B engineering drilling machines, matching with one Tulas air compressor GR 200-20, and adopting an impact drilling process; adopting a lower casing pipe to measure inclination in the drilled hole, using light to measure inclination, and adopting a JDT-5 type gyro inclinometer to measure inclination if necessary so as to ensure the vertical accuracy of the drilled hole;

II, drilling technical requirements are as follows:

during drilling, the drill collars are increased or decreased in time according to the requirements of the depth and the stratum condition, uniform and uniform drilling is required, the speed is strictly forbidden, and the pressure is suddenly large or small;

reasonably mastering the rotating speed, the pressure and the flushing amount, when a drill bit is added or replaced, the drilling tool is lowered to a position 0.3-0.5m away from the bottom of a hole to sweep the hole, the drilling tool is not stopped at a depth for long-term flushing, when power is cut off, the drilling tool is lifted to a safe depth, the power is cut off for more than two hours, all the drilling tools are lifted out, all the drilling tools are frequently checked in detail, bent drilling rods and the drilling rods which are excessively worn are forbidden to be used, the whole length of the drilling tool is rechecked when the hole is finished, rock powder is completely discharged by punching, and;

matching the freezing pipes on the ground, measuring the full length, recording, removing foreign matters in the pipes during pipe discharging, keeping clean, filling gaps around the freezing pipes with soil in time after pressure testing and sealing, and preventing slurry from mixing holes;

deflection: the average deviation rate of the freezing holes is not more than 5 per thousand, the distance between the final holes of the freezing holes is not more than the design value, otherwise, the holes are repaired, the freezing depth meets the design requirement, and the length of the lower pipe is not less than the depth of the designed freezing holes;

inclination measurement: in the freezing hole construction process, a lamplight theodolite is used for carrying out final hole and hole forming inclination measurement and drawing a freezing hole deflection plan in time;

foundation of a drill site: in order to ensure the drilling quality, a simple slurry groove is paved on site;

step four, freezing construction:

firstly, freezing construction main equipment: two W-YSLGF600 II type screw units, three IS150-125-315 type brine pumps, three IS150-125-315 type clear water pumps and four KST-80 type cooling towers, wherein the total electric load IS 666kw during freezing, and under the condition of considering large line voltage loss, three YC3 multiplied by 120+2 multiplied by 25 low-voltage rubber sleeve cables are selected for the whole freezing station and are respectively used for two freezing units and matched equipment;

secondly, the freezing station is installed: the freezing station is arranged at one side, the two units are installed in parallel for standby, and the freezing station occupies 200 square meters;

thirdly, installing a refrigerating unit:

1) positioning and fixing: according to a layout drawing of a freezing station, after a freezing unit is in place, the freezing unit is fixed with a foundation by bolts, the unit is leveled by a leveling ruler during fixing, and the unit is leveled by continuously adjusting a sizing block; adjusting cover plates at two ends of the condenser according to on-site pipeline arrangement, arranging a unit starting cabinet beside the unit, and simultaneously reserving an operation space between the unit starting cabinet and the unit;

2) and pipeline connection: the salt water pipeline and the clear water pipeline are connected with the unit by flanges, and valves are arranged and installed;

3) and sealing and detecting the unit: the refrigerating unit firstly carries out leak detection on a refrigerating system to ensure that the refrigerating unit has no leakage, and then fluorine is filled and oil is added after the system is ensured to have no leakage;

4) and oiling the unit: checking the amount of refrigerating machine oil in the unit, and if the amount of refrigerating machine oil in the unit does not meet the requirement, adding oil into the unit, wherein the refrigerating machine unit is selected from 46^#A refrigerator oil;

fourthly, installing a clear brine pump and a brine pump: checking a water pump and a motor to ensure that no damage is caused in the transportation, loading and unloading processes, checking tools and hoisting machinery, checking the foundation of the machine, horizontally leveling the foundation plane for mounting the pump, checking the levelness of the whole unit after the unit is placed, arranging respective supports for a suction pipeline and a discharge pipeline of the pump, not allowing the weight of the pipelines to be directly borne by the pump, ensuring that the rotation directions of a pump shaft and the motor are consistent, arranging a filter screen at the suction inlet of a clean water pump, arranging a filter screen in the middle of a brine tank, checking whether the pump, the pipelines and a joint have looseness, adding bearing lubricating oil into a bearing body, and observing that the oil level is required to be at the center line of an oil pointer and the lubricating oil is required to be replaced or supplemented in time;

fifthly, mounting of a cooling tower: during the installation process of the cooling tower, fire prevention needs to be paid attention to, electric welding or gas cutting is strictly forbidden to be used at the tower body and the vicinity of the tower body, and people in the field are not allowed to smoke, and safety measures are taken if open fire is used; the cooling tower foundation is kept horizontal, the support columns are required to be vertical to base planes, the height difference of each base plane is not more than +/-1 mm, and the allowable difference of the center distance is +/-2 mm; when the tower body is assembled, the bolts are symmetrically fastened, forced twisting installation is not allowed, and water leakage is avoided after assembly; the tower foot of the cooling tower is firmly fixed with the foundation; in the transportation and storage processes of the components of the cooling tower, no weight is allowed to be pressed on the components, the components are not exposed to the sun, and open fire is noticed; the water inlet pipe, the water outlet pipe and the water replenishing pipe of the cooling tower are separately provided with pipeline supports, so that the weight of a pipeline is prevented from being transferred to the tower body; the fan blades are kept properly and prevented from deforming, the motor and the transmission part need to be oiled and stored indoors, and impurities are carefully cleaned before being assembled in order to avoid entering a nozzle and an orifice; after the cooling tower is installed, cleaning dirt on the surfaces of the pipeline and the filler and on the water collecting tray and remainders in the tower, and flushing the system;

sixthly, debugging a refrigerating unit:

1) refrigerant charging: after field installation, if no accidental damage is found by appearance inspection, if the refrigerant is found to be leaked or insufficient, firstly finding out a leakage point and eliminating the leakage phenomenon, and then adding the refrigerant; during filling, the liquid is directly filled from the special liquid filling valve;

2) debugging: before formal start-up, the main electric control system is subjected to simulation action detection, namely, the main machine of the unit is not electrified, the control system is electrified, then the electric control system of the unit is detected through the internal setting of the unit, whether the components run normally or not is detected, if the electric control system has problems, the problem is solved in time, and finally, the main machine power supply is connected for debugging;

during commissioning, the following are noted:

checking whether valves at all places in the refrigeration system are in a normal opening state, particularly a gas exhaust stop valve, and not closing;

opening a cooling water valve of the condenser and a cooling water valve of the evaporator, wherein the flow rates of the cooling water and the cooling water are in accordance with the technical requirements of the unit; before starting, observing whether the power supply voltage of the unit is normal;

3) and operation: starting the unit according to the operating regulation requirement of the refrigerator, checking whether each parameter of the unit is normal or not according to the specification requirement of the unit after the unit is started, recording each data of the unit, paying attention to whether a load increasing mechanism and a load reducing mechanism of a compressor work normally or not in the running process of the unit, correctly using a safety protection device installed in a refrigeration system, and timely replacing the safety protection device if the safety protection device is damaged;

4) and (3) abnormal monitoring:

if the screw type water chilling unit is abnormal, stopping the machine for inspection immediately;

the screw type refrigeration compressor normally operates as follows:

the gauge pressure of the discharge pressure of the compressor is 0.8-1.5 MPa;

the exhaust temperature of the compressor is 45-90 ℃;

the oil temperature of the compressor is 40-55 ℃;

the oil pressure of the compressor is 0.2-0.3 MPa;

the sound is uniform and stable in the running process of the compressor, and no abnormal sound exists;

the condensing temperature of the unit is 3-5 ℃ higher than the cooling water temperature; the condensation temperature is controlled to be 40 ℃, and the water inlet temperature of the condenser is below 32 ℃;

the evaporation temperature of the unit is 3-4 ℃ lower than the outlet water temperature of the refrigerant water, and the outlet water temperature of the refrigerant water is 5-7 ℃;

seventhly, debugging of a clear brine pump and a brine pump:

checking whether the pump, the pipeline and the joint are loosened, rotating the pump by hand, and trying to see whether the pump shaft rotates flexibly;

adding bearing lubricating oil into the bearing body, observing that the oil level is required to be at the center line of the oil pointer, and timely replacing or supplementing the lubricating oil;

the motor is inching to try to see whether the motor steering is correct;

starting a motor, opening an outlet pressure gauge after the pump normally operates, gradually opening a gate valve after the pressure gauge displays a pressure value, and simultaneously checking the load condition of the motor;

observing whether the pump body and the pipeline vibrate excessively, and stopping to check the reason and process when the pump body and the pipeline vibrate excessively;

controlling the flow and the lift of the pump within the range indicated on the label to ensure that the pump operates at the highest efficiency point;

in the running process of the pump, the temperature of a bearing cannot exceed 35 ℃ of the ambient temperature, and the highest temperature cannot exceed 80 ℃; the pump is found to have abnormal sound and is immediately stopped for checking the reason;

eighthly, other:

the refrigerator oil is N46 refrigerator oil;

the refrigerant is Freon R-22;

the refrigerant agent is calcium chloride solution;

step five, breaking the conditions of the groove wall:

the breaking groove wall must have the following conditions:

the thickness of the frozen soil wall is more than or equal to 1.6m, the average temperature of the frozen soil is less than or equal to minus 10 ℃, the temperature of brine is between minus 28 ℃ and minus 30 ℃, the temperature difference of a brine return circuit is less than or equal to 2 ℃, and the temperature of a hole probing is less than or equal to minus 2 ℃;

judging the freezing effect of the frozen soil wall through exploratory hole observation, after freezing for 30 days, drilling a plurality of exploratory holes on a tunnel portal in a distributed manner before breaking the wall of the trench wall to judge the cementation condition of the frozen soil and the wall of the trench wall, wherein the exploratory hole depth needs to enter the continuous wall for 10-15cm, then measuring by using a thermodetector, and requiring the actual measurement temperature of each exploratory hole to be lower than-2 ℃, and when the completely reliable cementation of the frozen soil wall and the wall of the trench wall can be completely broken through the actual measurement temperature of the exploratory hole and the actual measurement temperature of the horizontal thermomet;

step six, a freezing pipe pulling process:

firstly, forced thawing: adopting a scheme of manual local thawing, and utilizing hot brine to circulate in a freezer to melt frozen soil around a freezing pipe;

secondly, heating saline water: using one 3m³The brine tank stores brine, six groups of 20kw electric heating wires are used for heating the brine, and the temperature is controlled at 75 +/-10 ℃;

thirdly, brine circulation: the brine pump IS used for circulating brine, the model of the water pump IS IS150-125-³/h；

Fourthly, unfreezing measurement: measuring the temperature change of the curtain at regular time every day by using a temperature measuring hole in the freezing curtain until the freezing curtain is raised to a positive temperature, and stopping the unfreezing operation;

fifthly, pulling out the freezing pipe: after the freezing pipe is unfrozen, discharging saline water in the pipe by using compressed air, trying to pull out by using a crane, and pulling up the pipe by 0.5m to ensure no abnormity, quickly pulling out the freezing pipe, wherein the pipe pulling-out is carried out by paying attention to the fact that the freezing pipe and a hook are in a line, the freezing pipe cannot be tightened, the freezing pipe is required to be rotated frequently when pulling out the pipe, and cannot be pulled out firmly, and if the freezing pipe cannot be pulled out, the hot saline water is required to be circulated continuously for unfreezing until the freezing pipe can be pulled out;

step seven, controlling frost heaving and thawing settlement:

the frost heaving is soil body expansion caused by water freezing when the soil body is frozen, and the frost heaving and the thawing settlement are controlled by adopting the following measures in the construction process:

firstly, after the freezing pipe is pulled out, filling and compacting the freezing hole in time by using yellow sand;

secondly, in the thawing stage of the frozen soil body, grouting and compacting the frozen soil body to a freezing reinforcement area by using grouting holes of tunnel pipe pieces, and grouting in a small-pressure and multi-grouting mode, wherein the grouting pressure is 0.2-0.5MPa, and the grout is single-liquid cement grout;

thirdly, a refrigerating unit with larger standard refrigerating capacity is selected, and the temperature of the brine is reduced to a design value in a short time, so that the development of frozen soil is accelerated, the strength of the frozen soil is improved, and the frost heaving and thawing settlement are reduced;

and fourthly, mastering and adjusting the temperature and the flow rate of the brine, adopting intermittent freezing and controlling the development amount of frozen soil so as to reduce frost heaving and thaw collapse.

The utility model has the advantages that:

the utility model provides a shield tunnel end frozen soil wall and ground are wall jointly reinforced structure and construction method has that the construction practicality is strong, construction quality control is convenient, the especially outstanding advantages such as effectual and safe and reliable of stagnant water of reinforcement effect have great popularization and application and worth. The utility model provides a technical scheme can carry out appropriate reinforcement for the stratum of areas such as coastal, coastal river, coastal lake rich in water sand bed end, can effectively solve the conventional not good problem of mode reinforcement effect of consolidating in above-mentioned area, guarantees that the shield constructs the machine and advances out of the hole smoothly.

Drawings

Fig. 1 is the combined reinforcement structure of the present invention is a schematic side view.

Fig. 2 is a schematic view of the top view structure of the joint reinforcement structure of the present invention.

Fig. 3 is the schematic view of the process flow of the construction of the frozen earth wall of the utility model.

Fig. 4 is the process flow schematic diagram of the drilling construction of the utility model.

Fig. 5 is a schematic view of the freezing construction process of the present invention.

The labels in the above figures are as follows:

1. frozen earth wall 2, ground wall 3, envelope 4, freezing pipe 5, shield tunnel

6. A shield machine.

Detailed Description

Please refer to fig. 1 to 5:

the utility model provides a shield tunnel end frozen soil wall links reinforced structure with ground even wall and links wall 2 including frozen soil wall 1 and ground, wherein frozen soil wall 2 sets up in the position department near envelope 3, and ground links wall 2 and establishes at the rear portion of frozen soil wall 1.

The frozen soil wall 1 is a vertical frozen soil wall, the diameter of freezing pipes 4 in the frozen soil wall 1 is 127mm, the freezing pipes 4 are arranged in two rows, the arrangement of the flower arrangement is carried out, the pipe spacing is 800mm, and the row spacing is 800 mm; the distance between the freezing pipe 4 close to the enclosure structure 3 and the wall side of the groove is 300-400mm, the length of the plane where the freezing pipe 4 is arranged is 3m on two sides of the shield tunnel 5, the freezing pipe 4 is partially frozen in the length from the vault 3m to the arch bottom 3m of the shield tunnel 5 in the depth direction, or is frozen in the full length in the length from the ground to the arch bottom 3m in the depth direction, the freezing pipe 4 is made of a seamless low-carbon steel pipe or a PVC plastic pipe or a PPR plastic pipe or an ABS plastic pipe or a PE plastic pipe, and the section of the freezing pipe 4 is circular, I-shaped, X-shaped, T-shaped or Y-.

The stress framework in the underground diaphragm wall 2 is a glass fiber reinforcement cage or a bamboo reinforcement cage, the wall body of the underground diaphragm wall 2 is formed by pouring cement concrete, the label is not lower than C30, the protective layer of the glass fiber reinforcement cage or the bamboo reinforcement cage is not less than 70mm, the thickness of the wall body of the underground diaphragm wall 2 is 800mm, the plane length of the underground diaphragm wall 2 is 3m on two sides of the shield tunnel 5, the underground diaphragm wall 2 is locally poured in the depth direction length from 3m of the vault of the shield tunnel 5 to 3m of the arch bottom, or the full-length pouring is carried out in the depth direction length from the ground to 3m of the arch bottom.

firstly, constructing the diaphragm wall 2, wherein the construction process comprises the following steps:

measuring and paying off → making a guide wall → mixing slurry → forming a groove and clearing the bottom of the diaphragm wall 2 → processing and hanging a glass fiber reinforcement cage or a bamboo reinforcement cage → pouring concrete → constructing a joint → drawing the top of a joint pipe → completing the whole construction;

and step two, construction of the frozen soil wall 1: the construction of the frozen soil wall 1 is that before the shield tunneling, a water-containing stratum in the working well end area is frozen into a closed waterproof curtain to form the frozen soil wall 1 by using an artificial refrigeration method, the curtain is used for resisting ground pressure, water pressure and isolating underground water, the safety of the shield machine 6 entering and exiting a hole is ensured, firstly, the drilling construction of a freezing hole is carried out, meanwhile, the installation construction of a freezing station is carried out, after the freezing hole construction is finished, the freezing hole series pipeline and the heat preservation work are carried out, then, the freezing is actively frozen, after the freezing is determined to meet the hole door chiseling condition through temperature measuring hole observation and calculation, the groove wall of a hole opening is broken, the shield machine 6 is forcedly unfrozen before entering and exiting the hole, meanwhile, the vertical freezing pipe 4 is pulled out to the upper part of the shield machine 6 to be kept frozen, after the shield machine 6 enters and exits the hole, the.

The concrete construction steps of the diaphragm wall 2 in the first step are as follows:

step one, measurement and paying-off:

measuring a control pile of a shaft line of the diaphragm wall 2 according to a shaft line control pile provided by a construction party, wherein the control pile adopts a protection pile, the elevation is led into a field, a closed loop measuring method is adopted, a level point in the field is set, the elevation of the diaphragm wall 2 is controlled according to the level point, and an instrument which is corrected through inspection is used for measurement;

step two, manufacturing a guide wall:

before the deep groove is excavated, excavating a guide channel along the longitudinal axis designed by the diaphragm wall 2, pouring reinforced concrete guide walls on two sides, and making the guide walls extend outwards by 200mm at corners so as to straighten and clean the corners when excavating the grooves;

the center lines of the guide wall and the underground diaphragm wall 2 are required to be consistent, and the vertical surface is required to be vertical;

step three, slurry preparation:

1) and preparing slurry: in the process of forming the groove on the diaphragm wall 2, in order to keep the stability of the soil wall of the excavated groove, slurry is uninterruptedly supplied to the groove, and the slurry mixing ratio is as follows: 8-12% of bentonite; CMC/0.8-1.2%; na (Na)₂CO₃1.5 to 4 percent; the slurry is pumped into a slurry storage tank for storage after being uniformly stirred in a stirring tank, new slurry can be used only after being stabilized for 24 hours, the specific mixing proportion is adjusted according to the actual construction condition, the performance of the newly-mixed slurry is tested every 24 hours, the performance is controlled to be adjusted at any time, and the slurry is recycled to be detected in each tank;

2) and slurry storage: storing the slurry by adopting a sheet iron box;

4) separating and purifying the slurry: in the construction process of the diaphragm wall 2, the slurry can be polluted and deteriorated, and after the slurry is used for one cycle, the slurry needs to be separated and purified so as to improve the reutilization rate of the slurry;

step four, grooving and bottom cleaning replacement of the underground diaphragm wall 2:

1) and forming grooves on the diaphragm wall 2:

during construction, the grab bucket is lifted slowly when entering and exiting a guide wall port during trench digging operation, so that mud is prevented from lifting waves, the stability of a soil layer below the guide wall of the front diaphragm wall 2 is influenced, qualified wall protection mud is continuously supplemented into the trench when the grab bucket rises, the rising speed of the grab bucket is adapted to the mud supplementing speed, the liquid level of the mud is kept within 30cm below the top surface of the guide wall, and the phenomenon of hole collapse caused by the fact that the mud in the trench falls too fast is avoided;

2) and bottom clearing replacement:

firstly, processing and hoisting a glass fiber reinforcement cage:

the glass fiber reinforcement cage in the underground diaphragm wall 2 is divided into an upper section and a lower section which are respectively lifted into a groove and then spliced into a whole frame at the notch for lifting operation;

1) reinforcing and binding glass fiber ribs:

the ground connecting wall 2 uses the glass fiber reinforcement in the shield propelling range, so that the glass fiber reinforcement cage belongs to a flexible structure at the shield ring, the glass fiber reinforcement cage is reinforced before hoisting, the reinforcement measure is to arrange a longitudinal through long steel bar truss, and the upper layer glass fiber reinforcement and the lower layer glass fiber reinforcement are fixed by adopting a steel pipe;

③ installing longitudinal steel bar trusses;

⑥, installing and inspecting the reinforced steel truss;

2) the hoisting point of the glass fiber reinforcement cage is set as follows:

3) hoisting the glass fiber reinforcement cage:

4) and installing the glass fiber reinforcement cage in place:

secondly, processing and hanging the bamboo reinforcement cage:

1) and constructing a bamboo reinforcement cage platform:

2) and forming bamboo ribs and bamboo splints:

3) and manufacturing a grouting pipe:

4) and manufacturing the bamboo reinforcement cage:

6) the bamboo reinforcement cage is required to be as follows:

step six, concrete pouring:

the design label of the concrete of the diaphragm wall 2 is C30 underwater concrete, the impermeability is S8, the slump of the concrete is 200 +/-20 mm, the diffusivity is 340 plus-380 mm, the concrete is transported to the site by a mixer truck, the used conduit for pouring the concrete is phi 250, the waterproof bolt adopts a plastic ball, each groove section adopts two conduits for pouring, the height difference of the first pouring conduit for pouring the concrete from the bottom of the groove section is not less than 30cm, and the concrete truck directly pours the guide conduit for the notch when pouring;

step seven, joint construction:

step eight, jacking and drawing the joint pipe:

The concrete construction steps of the second step of the construction of the frozen soil wall 1 are as follows:

step one, freezing design:

firstly, designing the thickness of a frozen wall:

3) and the size of the reinforcing body:

transverse width: 3m at two sides of the shield tunnel 5;

depth: local freezing is carried out in the depth direction length from the vault 3m to the arch bottom 3m of the shield tunnel 5, or full-length freezing is carried out in the depth direction length from the ground to the arch bottom 3 m;

secondly, arrangement of freezing holes: two rows of freezing holes are arranged, the flower arrangement is carried out, the hole spacing is 800mm, the row spacing is 800mm, and the distance between the vertical freezing holes close to the working well enclosure structure 3 and the groove wall edge is 300mm and 400 mm;

step two, designing a refrigerating system:

firstly, parameter selection:

1) the vertical freezing pipe 4 is a seamless low-carbon steel pipe with the diameter of 127mm multiplied by 4.5 mm;

3) saline water specific gravity 1.26;

4) the flow of the saline water in the freezing pipe 4 is 5m³/h；

5) The heat dissipation capability of the freezing pipe 4：260Kcal/m².h；

6) And the cold loss coefficient: 1.2;

secondly, calculating the cooling capacity requirement:

and (3) calculating freezing cold quantity demand: q is 1.2 pi.d.H.K

Wherein H is the total length of the freeze;

d-the diameter of the freezing pipe 4;

k-the heat dissipation coefficient of the freezing pipe 4.

Setting a freezing station, selecting types and quantity of units:

fourthly, a brine system:

2) the used salt is calcium chloride crystal with the content of 80 percent;

fifthly, a clear water system:

2) selecting 8m³Three clear water tanks;

3) fresh water replenishment amount: 30m³/h；

5) selecting four KST-80 type cooling towers;

sixthly, predicting frozen wall formation: taking the development speed of the freezing curtain to be 25 mm/day, taking the maximum hole distance of the freezing pipe 4 to be 800mm, and then the circle-crossing time is t₁800/2/25 is 16 days, the freezing wall cross-linking time is 20 days, and the whole active freezing time is more than 30 days.

Step three, drilling construction:

firstly, selecting the type of drilling equipment:

II, drilling technical requirements are as follows:

the freezing pipes 4 are matched on the ground, the full length is measured, the record is made, foreign matters in the pipes are removed when the pipes are put down, the pipes are kept clean, and after pressure test and sealing, gaps around the freezing pipes 4 are filled with soil in time to prevent mud from flowing through holes;

step four, freezing construction:

thirdly, installing a refrigerating unit:

sixthly, debugging a refrigerating unit:

during commissioning, the following are noted:

4) and (3) abnormal monitoring:

the screw type refrigeration compressor normally operates as follows:

the gauge pressure of the discharge pressure of the compressor is 0.8-1.5 MPa;

the exhaust temperature of the compressor is 45-90 ℃;

the oil temperature of the compressor is 40-55 ℃;

the oil pressure of the compressor is 0.2-0.3 MPa;

seventhly, debugging of a clear brine pump and a brine pump:

the motor is inching to try to see whether the motor steering is correct;

eighthly, other:

the refrigerator oil is N46 refrigerator oil;

the refrigerant is Freon R-22;

the refrigerant agent is calcium chloride solution;

step five, breaking the conditions of the groove wall:

the breaking groove wall must have the following conditions:

the thickness of the frozen soil wall 1 is more than or equal to 1.6m, the average temperature of the frozen soil is less than or equal to minus 10 ℃, the temperature of brine is between minus 28 ℃ and minus 30 ℃, the temperature difference of a brine return circuit is less than or equal to 2 ℃, and the temperature of a hole probing is less than or equal to minus 2 ℃;

judging the freezing effect of the frozen soil wall 1 through exploratory hole observation, after freezing for 30 days, drilling a plurality of exploratory holes distributed on a tunnel portal before breaking the wall of the trench wall to judge the cementation condition of the frozen soil and the wall of the trench wall, wherein the exploratory hole depth needs to enter the continuous wall for 10-15cm, then measuring by using a thermodetector, and requiring the actual measurement temperature of each exploratory hole to be lower than-2 ℃, and when the completely reliable cementation of the frozen soil wall 1 and the trench wall can be completely broken through the actual measurement temperature of the exploratory hole and the actual measurement temperature of the horizontal thermometric hole;

step six, the process for pulling out the freezing pipe 4 comprises the following steps:

firstly, forced thawing: adopting a scheme of manual local thawing, and utilizing hot brine to circulate in a freezer to melt frozen soil around the freezing pipe 4;

fifthly, pulling up the freezing pipe 4: after the freezing pipe 4 is unfrozen, discharging saline water in the pipe by using compressed air, trying to pull out by using a crane, quickly pulling out the freezing pipe 4 after the pipe is pulled out for 0.5m to ensure no abnormity, paying attention to the fact that the freezing pipe 4 and a hook form a line when the pipe is pulled out, the freezing pipe 4 cannot be too strong, rotating the freezing pipe 4 frequently when the pipe is pulled out, and the freezing pipe 4 cannot be pulled out firmly, if the pipe is not pulled out, continuously circulating hot saline water to unfreeze until the freezing pipe 4 can be pulled out;

step seven, controlling frost heaving and thawing settlement:

firstly, after the freezing pipe 4 is pulled out, filling and compacting the freezing hole with yellow sand in time;

Claims

1. The utility model provides a shield tunnel end frozen soil wall and ground are wall jointly reinforced structure which characterized in that: the underground continuous wall is arranged at the rear part of the frozen soil wall.

2. The shield tunnel end permafrost wall and diaphragm wall combined reinforcement structure of claim 1, characterized in that: the frozen soil wall is a vertical frozen soil wall, the diameter of freezing pipes in the frozen soil wall is 127mm, the freezing pipes are arranged in two rows, the flowers are arranged, the pipe spacing is 800mm, and the row spacing is 800 mm; the freezing pipe close to the enclosure structure is 400mm away from the side of the groove wall, the length of the plane where the freezing pipe is arranged is 3m of the two sides of the shield tunnel, the freezing pipe is partially frozen in the length from 3m of the vault of the shield tunnel to 3m of the vault, or is frozen in the full length in the length from the ground to 3m of the vault, the freezing pipe is made of a seamless low-carbon steel pipe or a PVC plastic pipe or a PPR plastic pipe or an ABS plastic pipe or a PE plastic pipe, and the section of the freezing pipe is circular, I-shaped, X-shaped, T-shaped or Y-shaped.

3. The shield tunnel end permafrost wall and diaphragm wall combined reinforcement structure of claim 1, characterized in that: the stress framework in the underground diaphragm wall is a glass fiber reinforcement cage or a bamboo reinforcement cage, the wall body of the underground diaphragm wall is formed by pouring cement concrete, the label is not lower than C30, the protective layer of the glass fiber reinforcement cage or the bamboo reinforcement cage is not less than 70mm, the thickness of the wall body of the underground diaphragm wall is 800mm, the plane length of the underground diaphragm wall is 3m of the two sides of the shield tunnel, the underground diaphragm wall is locally poured in the depth direction length from 3m of the vault of the shield tunnel to 3m of the arch bottom, or the full-length pouring is carried out in the depth direction length from the ground to 3m of the arch bottom.