CN110836121A - A kind of anti-floating reinforcement structure and construction method of operating subway tunnel - Google Patents

Abstract

The invention relates to an anti-floating reinforcement structure and a construction method for an already operated subway tunnel. The steel ferrule and the stiffening plate, the stiffening plate and the steel ferrule are welded, and the steel ferrule is fixed with the tunnel lining through wall-mounted expansion bolts; the external reinforcement structure includes grouting reinforcement of the soil body, and the grouting reinforcement soil body is symmetrically arranged in the tunnel lining The two sides are located at the upper part; the anti-floating structure includes an anchor rod, the anchor rod is arranged at the bottom of the tunnel lining, the top of the anchor rod is anchored into the track bed, and a grouting body is provided around the anchor rod at the lower part of the tunnel lining. The invention can reduce the influence of surrounding soil disturbance on the subway tunnel, increase the anti-floating performance and tunnel rigidity of the subway tunnel, and reduce the floating amount and the section deformation of the tunnel when the groundwater level rises or the soil overlying the tunnel is excavated.

Description

A kind of anti-floating reinforcement structure and construction method of operating subway tunnel

technical field

The invention relates to the technical field of anti-floating subway tunnels, in particular to an anti-floating reinforcement structure and a construction method of an already operated subway tunnel.

Background technique

With the increasing traffic flow, the traffic pressure on the surface road is gradually intensifying. As a result, the development and construction of underground space is also setting off a climax all over the country. The urban underpass tunnels spatially separate the cross-traffic flow, improve the traffic comfort, and greatly improve the traffic comfort. relieve the pressure of urban traffic. During the subway operation stage, due to changes in groundwater level or surrounding construction activities, shield tunnels will float upward, and the floating of segments will adversely affect train running speed, running safety, and passenger comfort.

As an important urban traffic lifeline, subway tunnels have extremely strict deformation requirements. According to the existing relevant regulations, the absolute maximum displacement of the tunnel should not exceed 20mm, the rebound deformation of the tunnel should not exceed 15mm, the radius of curvature of the tunnel deformation must be greater than 15000m, and the relative deformation must be less than 1/2500.

At present, the most common anti-floating method for tunnel structures is to use the weight of the soil buried deep below the ground and above the top of the subway tunnel in the design stage, so that the weight of these soils is sufficient to resist the buoyancy that the subway tunnel may experience underground. However, in coastal cities, the groundwater level is high all year round and the geological conditions are poor, and the groundwater level will change greatly with the seasonal changes. When the self-weight effect of the overlying soil above the underground tunnel structure cannot resist the buoyancy of groundwater, the structure will float up. In severe cases, the connection of shield segments will be cracked, which will endanger the safety of the structure. In addition, construction activities on the adjacent sides of existing subway tunnels are increasing day by day. When soil unloading works such as foundation pit excavation are required above the subway tunnel, the soil body in the pit will rebound due to the excavation of the foundation pit, which will affect the adjacent ground. The construction (construction) causes additional displacement, causing the floating deformation of the adjacent subway tunnel, resulting in a smaller vertical diameter of the tunnel, a larger horizontal diameter, and a change in the shape of the cross section of the tunnel. Exceeding the limit will lead to the damage of the tunnel segment, and even cause problems such as tunnel water inflow and collapse, endangering life and property safety.

With the rapid increase of urban rail transit operation mileage and the increase of operation time, and the adjacent area of shield tunnel has always been a hot spot for construction, it is expected that more and more floating diseases will occur in the tunnel during the operation stage of the subway. It is necessary to study the shield tunnel during the operation stage. The control measures for the floating disease of the tunnel segment, and the reasonable selection of tunnel anti-floating reinforcement measures and means to ensure the normal use of the subway tunnel.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the problems of anti-floating reinforcement of operating subway tunnels, insufficient bearing capacity of construction structures, weak construction integrity and other defects in the prior art due to the lack of effective measures. The invention discloses an anti-floating reinforcement structure and a construction method for a subway tunnel, which are combined, have simple steps, reasonable design, simple construction, good construction structure integrity, and are suitable for construction in the subway outage window period.

In order to achieve the purpose, the technical scheme provided by the invention is:

The invention relates to an anti-floating reinforcement structure for an already operated subway tunnel, which includes a tunnel lining, a track bed is arranged inside the tunnel lining, and caps are arranged on both sides of the track bed. An outer reinforcement structure and an anti-floating structure are arranged outside the tunnel lining; the inner reinforcement structure includes a steel ferrule and a stiffening plate arranged at intervals. The wall-mounted expansion bolts are fixed with the tunnel lining, the two sides of the steel ferrule are sealed with epoxy cement, and the gap between the steel ferrule and the tunnel lining is filled with epoxy resin; The soil reinforced by the slurry is symmetrically arranged at the upper part of the two sides of the tunnel lining; the anti-floating structure includes several bolts, the bolts are arranged at the bottom of the tunnel lining, the top of the bolts are anchored into the track bed, and the lower part of the tunnel lining is around the bolts With grout body.

Preferably, the steel ferrule includes a left arc-shaped steel plate and a right arc-shaped steel plate, and the stiffening plate includes a left stiffening plate and a right stiffening plate; the arc of the left arc-shaped steel plate and the right arc-shaped steel plate is the same as the inner arc of the tunnel lining Similarly, the inner surface of the tunnel lining is provided with screw holes, and the corresponding positions of the left and right curved steel plates are provided with screw holes. The left and right arc-shaped steel plates are connected to the tunnel lining through wall-mounted expansion bolts that pass through the screw holes; The tops of the plate and the right stiffening plate are provided with connecting top plates, and the connecting top plates on both sides are connected to each other by the pull bolts; the bottoms of the left arc steel plate and the right arc steel plate are welded with bottom connecting plates, and the bottom connecting plates are connected by anchor bolts The mating nuts are fixed on the upper surfaces of the caps on both sides.

Preferably, several grouting flower tubes are arranged in the grouting reinforcement soil body, the grouting flower tubes in the grouting reinforcement soil body on both sides are symmetrical on the left and right, and the left and right sides of the tunnel lining correspond to the grouting flower tubes. A grouting hole is provided at the location, and the grouting flower pipe runs through the grouting hole and is inserted into the reinforced soil on both sides of the tunnel lining, and the grouting hole is filled with sealing material to block the grouting hole.

Preferably, the anchor rod includes a main anchor rod, several anti-floating reinforcing ribs, a water-stop steel plate and a steel locator; At the intersection of the steel plates, the water-stop steel plates are buried in the ballast and welded with the steel bars of the ballast, and the steel bar locators are welded to the main anchor bars of the lower part of the tunnel lining; In the bent part, the bottom end of the anti-floating reinforcement is provided with a lap joint parallel to the direction of the main reinforcement of the anchor rod. It is 55 times the diameter of the anti-floating reinforcement.

The bearing platform is connected with the tunnel lining through several expansion bolts.

The present invention also relates to a construction method for the above-mentioned anti-floating reinforcement structure of an already operated subway tunnel, characterized in that it comprises the following steps:

1) Cut and chisel the ballast bed and water ditch on both sides of the subway track until the shield segment is exposed;

2) Construction of the cap at the position where the ballast bed is cut and chiseled on both sides of the subway track;

3) Drill grouting holes at the upper part of the two sides of the tunnel lining. After each drilled hole forms a grouting hole, immediately drive a grouting flower tube along the grouting hole, and inject cement slurry. After hardening, the grouting reinforcement soil is formed. Then pour waterproof concrete at the position of the grouting hole to form a sealing material;

4) Determine the cause of the tunnel floating, and calculate the anti-buoyancy F _{anti-floating} required for the single-ring tunnel segment;

5) Calculate the axial tension design value of a single anchor rod, the anchor rod reinforcement, the anchor rod length, and the anchorage length of the anchor body and the anchor rod according to the buoyancy F _floating value of the single ring tunnel segment;

6) Drill the track bed at the subway tunnel and set the anchor rod according to the parameters calculated in step 5;

7) Install the ferrule and stiffener.

Preferably, the step 4) is the floating of the tunnel caused by the rise of groundwater, and the calculation steps of the _anti -buoyancy F required by the single-ring tunnel segment are as follows:

4.1) Calculate the effective weight G _soil of the overlying soil column of the single-ring tunnel segment,

4.2) Calculate the _self -weight G of the single-ring tunnel segment,

_Gself =δπ(R ² −r ² )γ _c ;

4.3) Calculate the groundwater buoyancy F _float on the single-ring tunnel segment,

F _float = δπR ² γ _w ;

4.4) Calculate the required anti-buoyancy F _{anti-buoyancy} ,

Among them, γ _a is the saturated bulk density of soil, γ _w is the bulk density of water, R is the outer diameter of the shield tunnel, h is the thickness of the overlying soil layer on the pipeline, δ is the width of the single ring segment, and r is the inner diameter of the shield tunnel; _{γ f} is the safety anti _{- floating} coefficient of the shield tunnel in the use stage, which is taken as 1.2; Anti-float sub-item coefficient, take 1.0.

Preferably. The step 4) is that the unloading above the tunnel causes the tunnel to float, and the calculation steps of the _anti -buoyancy F required by the single-ring tunnel segment are as follows:

4.1) According to the unloading load pd _ξ d _η on the coordinates (ξ, η) of any point at the bottom of the foundation pit, calculate the additional stress σ _z at the tunnel axis (x, y, z ₀ ),

In the formula,

υ is Poisson’s ratio; z ₀ is the distance between the tunnel centerline and the surface; h is the excavation depth of the foundation pit;

4.2) For each ring of shield segments, assuming that the additional stress at each point at the axis is the same, the additional load F received by each ring segment due to the excavation of the foundation pit is:

F _additional = δRσ _z ;

4.3) According to the force balance relationship, take F _{anti-floating} = F _additional .

Preferably, the concrete steps of described step 5) are:

5.1) According to the F _{anti-floating} calculated in step 4, calculate the standard value N _ak of the axial tension of the bolt,

N _ak =F _anti-float ;

5.2) Calculate the design value N _t of the axial tensile force of a single bolt according to the standard value of the axial tensile force N _ak ,

N _t =γ _Q N _ak ,

In the formula, γ _Q is the load sub-item coefficient, which is taken as 1.3;

5.3) Calculate the cross-sectional area A _s of the reinforcement bar of the anchor rod,

In the formula, K _t is the safety factor of the tensile strength of the bolt body; f _yk is the standard value of the tensile strength of the steel bar;

And according to the calculated cross-sectional area A _s of the anchor bar, determine the actual number of anchor bars;

5.4) Calculate the length L _a1 between the stratum and the anchor and the L _a2 between the anchor and the steel bar,

Select the larger value between L _a1 and L _a2 as the anchoring length L _a between the anchor and the bolt (8);

为钢筋截面的粘结强度的降低系数，取值范围在0.6～0.85之间；ψ为锚杆锚固长度对粘结强度的影响系数，取1.0。In the formula, f _mg is the standard value of the bond strength between the stratum and the anchor grouting body; f _ms is the standard value of the bond strength between the steel bar and the anchor grouting body; K is the pullout safety factor of the anchor rod, which is taken as 2.0; D is the diameter of the drilled hole in the anchoring section of the bolt, which is 150mm; d is the diameter of the steel bar of the bolt, which is determined according to the actual reinforcement; n is the number of reinforcement bars of the anchor, which is determined according to the actual reinforcement of each ring segment;

is the reduction coefficient of the bond strength of the steel bar section, and the value ranges from 0.6 to 0.85; ψ is the influence coefficient of the anchorage length of the bolt on the bond strength, which is taken as 1.0.

Preferably, the installation steps of the anchor rod in step 6) are:

6.1) Chisel the concrete according to the track of the concrete chisel of the track bed, and then use the down-the-hole hammer to form a hole;

6.2) Put the pre-fabricated bolt into the drilled hole, and use the method of secondary grouting for grouting;

6.3) After the initial setting of the slurry, refill the high-strength concrete to fill up the concrete chiseled part of the track bed.

Preferably, the installation steps of the rigid ferrule and the stiffening plate in the step 7) are:

7.1) Set corresponding screw holes on the tunnel lining according to the position of the screw holes of the steel ferrule;

7.2) Weld the left stiffening plate on the left arc-shaped steel plate, weld the right stiffening plate on the right arc-shaped steel plate, hoist the left arc-shaped steel plate and the right arc-shaped steel plate to the designated position, and use the wall-mounted expansion bolts to fix the left arc-shaped steel plate. And the right stiffener is anchored on the tunnel lining;

7.3) Connect the connecting top plates of the curved steel plates on both sides to each other with the tension bolts;

7.4) Use anchor bolts to fix the left arc-shaped steel plate and the left stiffening plate, and the right arc-shaped steel plate and the right stiffening plate on the bearing platforms on both sides.

Adopt the scheme involved in the present invention, compared with the prior art, there are the following beneficial effects:

(1) In the present invention, an inner reinforcement structure composed of a steel ferrule and a stiffening plate is provided inside the tunnel lining, and the left and right sides of the outside of the tunnel lining are respectively provided with grouting reinforcement soil, which can quickly suppress the upward trend of the tunnel and play a role in The effect of "quick effect", combined with the inner reinforcement structure, forms a reinforcement system on the inside and outside of the tunnel lining, which improves the stability of the tunnel structure, reduces the cross-section deformation of the tunnel, and reduces the damage to the tunnel caused by surrounding construction activities.

(2) In the present invention, an anti-floating structure is set at the bottom of the tunnel lining, and the anti-floating structure cooperates with the overlying soil of the tunnel to offset the buoyancy of groundwater on the tunnel. When the water level changes or the overlying soil is excavated, the anti-floating structure prevents the tunnel. The function of floating can avoid the structural damage caused by the floating of the tunnel, and can control the displacement value of the tunnel for a long time during the load period.

(3) The construction method in which the anti-floating structure is arranged at the bottom of the tunnel lining involved in the present invention is simple in steps, mostly based on the assembled structure, which improves the construction efficiency, and is suitable for the engineering characteristics of the operating tunnel in the short construction window period, which is the most suitable for the operating tunnel. The floating deformation of the tunnel provides a new idea of active anti-floating.

(4) The present invention simultaneously solves two kinds of tunnel structural disasters, namely, the floating deformation of the tunnel and the deformation of the tunnel section, which greatly reduces the construction cost, improves the deformation resistance of the tunnel, prolongs the service life of the tunnel, and has high practical value and use effect. it is good.

(5) The technology disclosed in the present invention can be used to correct the floating deformation of the operating subway tunnels with different diameters and different regions, and is especially suitable for tunnel protection and reinforcement in dangerous strata prone to lining diseases such as water-rich and weak areas. Wide.

Description of drawings

Fig. 1 is the structural schematic diagram of the subway tunnel anti-floating reinforcement structure involved in the present invention;

Fig. 2 is the A-A sectional view of the subway tunnel anti-floating reinforcement structure shown in accompanying drawing 1;

Fig. 3 is the A-A sectional view of the grouting hole, the bolt hole and the screw hole forming structure;

Fig. 4 is the A-A sectional view of the structure after setting the anchor rod;

Figure 5 is a large sample diagram of the anchor node;

Figure 6 is a 1-1 sectional view of a large sample of an anchor node;

Figure 7 is a large sample drawing of the anchor rod;

Figure 8 is the reinforcement diagram of the anchor rod;

Figure 9 is a schematic diagram of the calculation of the floating of the tunnel caused by the rise of the water level;

Figure 10 is a schematic diagram of the tunnel floating calculation caused by unloading above the tunnel;

Fig. 11 is the displacement monitoring diagram of the tunnel segment.

Labeling instructions: 1-tunnel lining, 2-track bed, 3-cap, 4-steel ring, 5-stiffening plate, 6-wall expansion bolt, 7-grouting reinforcement, 8-anchor rod, 9-grouting Body, 10-grouting flower tube, 11-left curved steel plate, 12-right curved steel plate, 13-left stiffening plate, 14-right stiffening plate, 15-connecting top plate, 16-sealing material, 17-anchor bolt , 18- Bottom connecting plate, 19- Pair of tie bolts, 20- Ballistic bar, 21- Grouting hole, 22- Anchor rod hole, 23- Expansion bolt, 24- Screw hole, 25- Anchor rod main reinforcement, 26- Anti-floating Reinforcing ribs, 27-water-stop steel plate, 28-steel bar locator, 29-track bed concrete chisel trace.

Detailed ways

In order to further understand the content of the present invention, the present invention is described in detail with reference to the embodiments. The following embodiments are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

Example 1

With reference to Figures 1 to 4, the present invention relates to an anti-floating reinforcement structure for an already operating subway tunnel, which is used to solve the problem of tunnel floating caused by rising water level or unloading above the tunnel. The structure includes a tunnel lining 1, The inside of the tunnel lining 1 is provided with a ballast bed 2 and an inner reinforcement structure, the outside of the tunnel lining 1 is provided with an outer reinforcement structure and an anti-floating structure, and a cap 3 is provided on both sides of the ballast bed 2, and the cap 3 is connected with the tunnel lining 1 through a number of expansion bolts 23 .

As shown in Figures 1 to 4, the inner reinforcement structure includes a steel ferrule 4 and a stiffening plate 5 arranged at intervals, the stiffening plate 5 is welded with the steel ferrule 4, and the steel ferrule 4 includes a left arc-shaped steel plate 11 and a right The arc steel plate 12 and the stiffening plate 5 include a left stiffening plate 13 and a right stiffening plate 14; the arc of the left arc steel plate 11 and the right arc steel plate 12 is the same as the inner arc of the tunnel lining 1, and the inner surface of the tunnel lining 1 is provided with screw holes 24. There are screw holes on corresponding positions of the left arc-shaped steel plate 11 and the right arc-shaped steel plate 12. The left arc-shaped steel plate 11 and the right arc-shaped steel plate 12 are arranged close to the inner surface of the tunnel lining 1. The left arc-shaped steel plate 11 and the right arc-shaped steel plate The steel plates 12 are all connected to the tunnel lining 1 through the wall-mounted expansion bolts 6 passing through the screw holes 24, so that the steel ferrule 4 is closely attached to the inner surface of the tunnel lining 1. Both sides of the steel ferrule 4 are sealed with epoxy cement, and the steel ferrule The gap between 4 and the tunnel lining 1 is filled with epoxy resin; the left stiffening plate 13 is welded and connected along the central axis of the left arc-shaped steel plate 11, the right stiffening plate 14 is welded and connected along the central axis of the right arc-shaped steel plate 12, and the left stiffening plate 13 and the top of the right stiffening plate 14 are provided with a connecting top plate 15, and the connecting top plates 15 on both sides are connected to each other through a pair of tension bolts 19; the bottom of the left arc-shaped steel plate 11 and the right arc-shaped steel plate 12 are welded with a bottom connecting plate 18, The bottom connecting plate 18 is fixed on the upper surfaces of the bearing platforms 3 on both sides by means of anchor bolts 17 and nuts.

The external reinforcement structure described in conjunction with Figures 1, 2 and 4 includes a grouting reinforcement soil body 7, and the grouting reinforcement soil body 7 is symmetrically arranged at the upper part of both sides of the tunnel lining 1. The grouting reinforcement 7 is formed by several grouting. The flower tube 10 injects cement slurry into the soil on both sides, and formed after the cement slurry hardens, the grouting flower tube 10 will not be pulled out; The left and right sides of 1 are provided with grouting holes 21 at the positions corresponding to the grouting flower tube 10. The grouting flower tube 10 penetrates the grouting hole 21 and is inserted into the soil on both sides of the tunnel lining 1, and is injected into the soil through the grouting flower tube 10. Cement slurry, the cement slurry is hardened to form a reinforced soil body 7, and after the cement slurry is injected, concrete is poured in the grouting hole 21 to form a filling and sealing material 16, which is used to block the grouting hole 21 and prevent the cement slurry from entering the grouting hole. 21 backflows.

As shown in Figures 1 to 4, the anti-floating structure includes several anchor rods 8. As shown in Figures 5 to 7, the anchor rod 8 includes anchor rod main bars 25, several anti-floating reinforcement ribs 26, and water-stop steel plates 27. and the steel bar locator 28; the main anchor bar 25 runs through the water-stop steel plate 27, and the bottom end of the anti-floating reinforcing bar 26 is welded at the intersection of the anchor bar main bar 25 and the water-stop steel plate 27, and the water-stop steel plate 27 is buried in the ballast 2, and Welded with the ballast reinforcement 20, the reinforcement locator 28 is welded to the main anchor reinforcement 25 of the lower part of the tunnel lining 1; as shown in Figures 5, 7 and 8, the top of the main anchor reinforcement 25 and the anti-floating reinforcement 26 Both are provided with a bent part, the bottom end of the anti-floating reinforcing rib 26 is provided with an overlapping part parallel to the main anchor 25, and the length of the bent part is at least 15 times the diameter of the anchor main rib 25 or the anti-floating reinforcing rib 26 , the length of the overlapping part is at least 55 times the diameter of the anti-floating reinforcement 26, the anchor rod 8 is inserted into the soil provided at the bottom of the tunnel lining 1, the reinforcement locator 28 is located in the anchor rod hole 22, and the outer diameter of the reinforcement locator 28 Slightly smaller than the diameter of the bolt hole 22, the cement slurry can pass through the gap between the steel bar locator 28 and the bolt hole 22, the top of the bolt 8 is anchored into the track bed 2, and cement is injected around the bolt 8 in the part below the tunnel lining 1 The grout forms the grout body 9 .

Example 2

When the operating subway tunnel floats up due to the rising water level, the following steps are used for construction:

1) Select manipulators and flatbed trucks for construction according to the construction environment such as the limit of the operating line, the minimum radius of the line, and the maximum slope; Then, the track bed 2 and the water ditch on both sides of the subway track are cut and chiseled until the shield segment is exposed. After cutting, the side of the track bed 2 is chiseled. The high-pressure water gun cleans the surface of the tunnel lining 1, and treats loose animals such as disintegration and calcification on the surface of the segment.

2) Construction of platform 3 at the position where the ballast bed is cut and chiseled on both sides of the subway track: According to the cutting size of the ballast bed 2, the platform 3 is staked out and processed on site, transported to the site by a special flatbed truck, and the platform 3 is hoisted in place and then implanted The concrete anchors 100mmM16 stainless steel expansion bolts 23 on the segment, and then fixes the cap 3, and re-grows cement at the joint, so that the cap 3 and the track bed 2 form a whole.

3) Drill grouting holes 21 at the upper part of both sides of the tunnel lining 1, and set up two rows on each side with 3 holes in each row. After each drilled hole forms a grouting hole 21, immediately drive grouting flowers along the grouting hole 21. Pipe 10, the grouting flower pipe 10 has a driving depth of 2m, and injects grout with a grouting pressure of 0.3-0.5Mpa. After the grout is hardened, the grouting reinforcement soil 7 is formed, and then water-proof concrete is poured into the grouting hole 21. The sealing material 16 is formed, and the function of the sealing material 16 is to prevent the groundwater from entering the tunnel lining 1 and the cement slurry from seeping out.

4) Determine the cause of the tunnel floating, and calculate the anti-buoyancy F _{anti-floating} required for the single-ring tunnel segment. In the present embodiment, it is the tunnel floating caused by the rise of the water level. Combined with Figure 9, the calculation method is:

4.1) Calculate the effective weight G _soil of the overlying soil column of the single-ring tunnel segment,

4.2) Calculate the _self -weight G of the single-ring tunnel segment,

_Gself =δπ(R ² −r ² )γ _c ;

4.3) Calculate the groundwater buoyancy F _float on the single-ring tunnel segment,

F _float = δπR ² γ _w ;

4.4) Calculate the required anti-buoyancy F _{anti-buoyancy} ,

Among them, γ _a is the saturated bulk density of soil, γ _w is the bulk density of water, R is the outer diameter of the shield tunnel, h is the thickness of the overlying soil layer on the pipeline, δ is the width of the single ring segment, and r is the inner diameter of the shield tunnel; _{γ f} is the safety anti _{- floating} coefficient of the shield tunnel in the use stage, which is taken as 1.2; Anti-float sub-item coefficient, take 1.0.

5) Calculate the axial tension design value of a single anchor rod 8, the reinforcement of the anchor rod 8, the length of the anchor rod 8, the anchoring length of the anchor body and the anchor rod 8 according to the _floating value of the buoyancy F of the single-ring tunnel segment, and the specific steps for:

5.1) According to the F _{anti-floating} calculated in step 4, calculate the standard value N _ak of the axial tension of the bolt,

N _ak =F _anti-float ;

5.2) Calculate the design value N _t of the axial tensile force of a single bolt according to the standard value of the axial tensile force N _ak ,

N _t =γ _Q N _ak ,

In the formula, γ _Q is the load sub-item coefficient, which is taken as 1.3;

5.3) Calculate the cross-sectional area A _s of the reinforcement bar of the anchor rod,

In the formula, K _t is the safety factor of the tensile strength of the bolt body; f _yk is the standard value of the tensile strength of the steel bar;

And according to the calculated cross-sectional area A _s of the anchor bar, determine the actual number of anchor bars;

5.4) Calculate the length L _a1 between the stratum and the anchor and the L _a2 between the anchor and the steel bar,

Select the larger value between L _a1 and L _a2 as the anchoring length L _a between the anchor and the bolt (8);

为钢筋截面的粘结强度的降低系数，取值范围在0.6～0.85之间；ψ为锚杆锚固长度对粘结强度的影响系数，取1.0。In the formula, f _mg is the standard value of the bond strength between the stratum and the anchor grouting body; f _ms is the standard value of the bond strength between the steel bar and the anchor grouting body; K is the pullout safety factor of the anchor rod, which is taken as 2.0; D is the diameter of the drilled hole in the anchoring section of the bolt, which is 150mm; d is the diameter of the steel bar of the bolt, which is determined according to the actual reinforcement; n is the number of reinforcement bars of the anchor, which is determined according to the actual reinforcement of each ring segment;

is the reduction coefficient of the bond strength of the steel bar section, and the value ranges from 0.6 to 0.85; ψ is the influence coefficient of the anchorage length of the bolt on the bond strength, which is taken as 1.0.

6) Drilling the track bed at the subway tunnel and setting the anchor rod 8 according to the parameters calculated in step 5), the specific method is:

6.1) According to the principle of planar arrangement, the line positioning is arranged at the four corner points of the square with a side length of 60cm, and the position of the anchor rod is marked, and the concrete is chiseled according to the track 29 of the concrete chisel of the track bed to form a circular truncated groove. When chiseling, the damage to the steel bars of the track bed should be minimized, and then the down-the-hole hammer should be used to form holes. The diameter deviation should not be greater than 2cm, and the depth deviation should not be greater than 1% of the design depth. When drilling, the steel bars of track bed 2 and tunnel lining 1 should be avoided. The structure after the hole formation is shown in accompanying drawing 3;

6.2) Put the prefabricated bolt 8 into the drill hole, and use the method of secondary grouting, and the grouting pressure is greater than 1.0Mpa to carry out the grouting operation;

6.3) After the initial setting of the slurry to form the grouting body 9, the high-strength concrete is refilled above the welded water-stop steel plate 27 to fill the chiseled part of the track bed concrete to form the structure of FIG. 4 .

7) Install the rigid ferrule 4 and the stiffening plate 5. The installation method of the rigid ferrule 4 and the stiffening plate 5 is:

7.1) Set corresponding screw holes 24 on the tunnel lining 1 according to the position of the screw holes of the steel ferrule, and set 2 rows of screw holes on the segment of the tunnel lining 1 on the left side and evenly arranged in the circumferential direction, 6 in each row, and 1 in the right tunnel lining 1 The same is true for the segment;

7.2) The left and right arc-shaped steel plates are made of steel rods with a section size of 20mm × 150mm, and the arc is the same as that of the inner wall of the tunnel lining 1. The left and right stiffening plates are selected from steel strips with a section size of 20mm × 80mm, and the arc is the same as that of the arc-shaped steel plate. The left stiffening plate 13 is welded on the left arc-shaped steel plate 11, and the right stiffening plate 14 is welded on the right arc-shaped steel plate 12. The steel plates are welded together as a whole to ensure a good stress system, and the welds are all grooved. Welding, gas shielded welding is used at the same time, and the weld level is required to be level 3 (the surface of the steel is subjected to anti-corrosion treatment before entering the site, and the weld needs to be redone anti-corrosion treatment). The left arc steel plate 11 and the right arc steel plate 12 are hoisted by a robot to the designated position, and anchor the left arc-shaped steel plate 11 and the right stiffening plate 14 on the tunnel lining 1 with wall-mounted expansion bolts 6;

7.3) Connect the connecting top plates 15 of the arc-shaped steel plates on both sides to each other with the tension bolts 19;

7.4) Use anchor bolts 17 to fix the left arc-shaped steel plate 11 and the left stiffening plate 13, the right arc-shaped steel plate 12 and the right stiffening plate 14 on the bearing platforms 3 on both sides respectively to form an inner reinforcement structure, as shown in Figure 2. After the left and right arc-shaped steel plates 11 and 12 form a complete rigid ferrule 4, epoxy cement is used to seal the joints between the two sides of the rigid ferrule 4 and the segment of the tunnel lining 1, and both sides of the rigid ferrule 4 are sealed Reserve grouting holes and air outlet holes, with no less than 4 segments on each side, and then use a small electric grouting pump to inject epoxy resin from bottom to top until the resin overflows from the top reserved hole to mark the end of construction, and repeat the process. Pressure injection is carried out, and finally pipelines, drainage ditches and other facilities are restored.

With reference to Figure 11, during the construction process, comprehensive real-time monitoring of the deformation of the tunnel, such as settlement, horizontal displacement, ellipticity, and convergence, is carried out. The value represents the settlement, and by arranging the present invention on the segment, the upward tendency of the tunnel segment is effectively suppressed, and a significant drop occurs and remains stable within the allowable range of displacement.

Example 3

When the operating subway tunnels float up due to unloading above the tunnels, the following steps are used for construction:

1) Select manipulators and flatbed trucks for construction according to the construction environment such as the limit of the operating line, the minimum radius of the line, and the maximum slope; Then, the track bed 2 and the water ditch on both sides of the subway track are cut and chiseled until the shield segment is exposed. After cutting, the side of the track bed 2 is chiseled. The high-pressure water gun cleans the surface of the tunnel lining 1, and treats loose animals such as disintegration and calcification on the surface of the segment.

2) Construction of platform 3 at the position where the ballast bed is cut and chiseled on both sides of the subway track: According to the cutting size of the ballast bed 2, the platform 3 is staked out and processed on site, transported to the site by a special flatbed truck, and the platform 3 is hoisted in place and then implanted The concrete anchors 100mmM16 stainless steel expansion bolts 23 on the segment, and then fixes the cap 3, and re-grows cement at the joint, so that the cap 3 and the track bed 2 form a whole.

3) Drill grouting holes 21 at the upper part of both sides of the tunnel lining 1, and set up two rows on each side with 3 holes in each row. After each drilled hole forms a grouting hole 21, immediately drive grouting flowers along the grouting hole 21. Pipe 10, the grouting flower pipe 10 has a driving depth of 2m, and injects grout with a grouting pressure of 0.3-0.5Mpa. After the grout is hardened, the grouting reinforcement soil 7 is formed, and then water-proof concrete is poured into the grouting hole 21. The sealing material 16 is formed, and the function of the sealing material 16 is to prevent the groundwater from entering the tunnel lining 1 and the cement slurry from seeping out.

4) Determine the cause of the tunnel floating, and calculate the anti-buoyancy F _{anti-floating} required for the single-ring tunnel segment. In this embodiment, the tunnel is floating due to unloading above the tunnel. Combined with Figure 10, the calculation method is:

4.1) According to the unloading load pd _ξ d _η on the coordinates (ξ, η) of any point at the bottom of the foundation pit, calculate the additional stress σ _z at the tunnel axis (x, y, z ₀ ),

In the formula,

υ is Poisson’s ratio; z ₀ is the distance between the tunnel centerline and the surface; h is the excavation depth of the foundation pit;

4.2) For each ring of shield segments, assuming that the additional stress at each point at the axis is the same, the _additional load F received by each ring segment due to the excavation of the foundation pit is:

F _additional = δRσ _z ;

4.3) According to the force balance relationship and the tunnel design specification,

F _anti-float ≥ F _additional

Then take F _anti-float = F _additional .

5) Calculate the axial tension design value of a single anchor rod 8, the reinforcement of the anchor rod 8, the length of the anchor rod 8, the anchoring length of the anchor body and the anchor rod 8 according to the _floating value of the buoyancy F of the single-ring tunnel segment, and the specific steps for:

5.1) According to the F _{anti-floating} calculated in step 4, calculate the standard value N _ak of the axial tension of the bolt,

N _ak =F _anti-float ;

5.2) Calculate the design value N _t of the axial tensile force of a single bolt according to the standard value of the axial tensile force N _ak ,

N _t =γ _Q N _ak ,

In the formula, γ _Q is the load sub-item coefficient, which is taken as 1.3;

5.3) Calculate the cross-sectional area A _s of the reinforcement bar of the anchor rod,

In the formula, K _t is the safety factor of the tensile strength of the bolt body; f _yk is the standard value of the tensile strength of the steel bar;

And according to the calculated cross-sectional area A _s of the anchor bar, determine the actual number of anchor bars;

5.4) Calculate the length L _a1 between the stratum and the anchor and the L _a2 between the anchor and the steel bar,

Select the larger value between L _a1 and L _a2 as the anchoring length L _a between the anchor and the anchor rod 8;

为钢筋截面的粘结强度的降低系数，取值范围在0.6～0.85之间；ψ为锚杆锚固长度对粘结强度的影响系数，取1.0。In the formula, f _mg is the standard value of the bond strength between the stratum and the anchor grouting body; f _ms is the standard value of the bond strength between the steel bar and the anchor grouting body; K is the pullout safety factor of the anchor rod, which is taken as 2.0; D is the diameter of the drilled hole in the anchoring section of the bolt, which is 150mm; d is the diameter of the steel bar of the bolt, which is determined according to the actual reinforcement; n is the number of reinforcement bars of the anchor, which is determined according to the actual reinforcement of each ring segment;

is the reduction coefficient of the bond strength of the steel bar section, and the value ranges from 0.6 to 0.85; ψ is the influence coefficient of the anchorage length of the bolt on the bond strength, which is taken as 1.0.

6) Drilling the track bed at the subway tunnel and setting the anchor rod 8 according to the parameters calculated in step 5), the specific method is:

6.1) According to the principle of planar arrangement, the line positioning is arranged at the four corner points of the square with a side length of 60cm, and the position of the anchor rod is marked, and the concrete is chiseled according to the track 29 of the concrete chisel of the track bed to form a circular truncated groove. When chiseling, the damage to the steel bars of the track bed should be minimized, and then the down-the-hole hammer should be used to form holes. The diameter deviation should not be greater than 2cm, and the depth deviation should not be greater than 1% of the design depth. When drilling, the steel bars of track bed 2 and tunnel lining 1 should be avoided. The structure after the hole formation is shown in accompanying drawing 3;

6.2) Put the prefabricated bolt 8 into the drill hole, and use the method of secondary grouting, and the grouting pressure is greater than 1.0Mpa to carry out the grouting operation;

6.3) After the initial setting of the slurry to form the grouting body 9, the high-strength concrete is refilled above the welded water-stop steel plate 27 to fill the chiseled part of the track bed concrete to form the structure of FIG. 4 .

7) Install the rigid ferrule 4 and the stiffening plate 5. The installation method of the rigid ferrule 4 and the stiffening plate 5 is:

7.1) Set corresponding screw holes 24 on the tunnel lining 1 according to the position of the screw holes of the steel ferrule, and set 2 rows of screw holes on the segment of the tunnel lining 1 on the left side and evenly arranged in the circumferential direction, 6 in each row, and 1 in the right tunnel lining 1 The same is true for the segment;

7.2) The left and right arc-shaped steel plates are made of steel rods with a section size of 20mm × 150mm, and the arc is the same as that of the inner wall of the tunnel lining 1. The left and right stiffening plates are selected from steel strips with a section size of 20mm × 80mm, and the arc is the same as that of the arc-shaped steel plate. The left stiffening plate 13 is welded on the left arc-shaped steel plate 11, and the right stiffening plate 14 is welded on the right arc-shaped steel plate 12. The steel plates are welded together as a whole to ensure a good stress system, and the welds are all grooved. Welding, gas shielded welding is used at the same time, and the weld level is required to be level 3 (the surface of the steel is subjected to anti-corrosion treatment before entering the site, and the weld needs to be redone anti-corrosion treatment). The left arc steel plate 11 and the right arc steel plate 12 are hoisted by a robot to the designated position, and anchor the left arc-shaped steel plate 11 and the right stiffening plate 14 on the tunnel lining 1 with wall-mounted expansion bolts 6;

7.3) Connect the connecting top plates 15 of the arc-shaped steel plates on both sides to each other with the tension bolts 19;

7.4) Use anchor bolts 17 to fix the left arc-shaped steel plate 11 and the left stiffening plate 13, the right arc-shaped steel plate 12 and the right stiffening plate 14 on the bearing platforms 3 on both sides respectively to form an inner reinforcement structure, as shown in Figure 2. After the left and right arc-shaped steel plates 11 and 12 form a complete rigid ferrule 4, epoxy cement is used to seal the joints between the two sides of the rigid ferrule 4 and the segment of the tunnel lining 1, and both sides of the rigid ferrule 4 are sealed Reserve grouting holes and air outlet holes, with no less than 4 segments on each side, and then use a small electric grouting pump to inject epoxy resin from bottom to top until the resin overflows from the top reserved hole to mark the end of construction, and repeat the process. Pressure injection is carried out, and finally pipelines, drainage ditches and other facilities are restored.

With reference to Figure 11, during the construction process, comprehensive real-time monitoring of the deformation of the tunnel, such as settlement, horizontal displacement, ellipticity, and convergence, is carried out. The value represents the settlement, and by arranging the present invention on the segment, the upward tendency of the tunnel segment is effectively suppressed, and a significant drop occurs and remains stable within the allowable range of displacement.

The present invention has been described in detail above with reference to the embodiments, but the above contents are only preferred embodiments of the present invention and cannot be considered to limit the implementation scope of the present invention. All equivalent changes and improvements made according to the scope of the application of the present invention should still fall within the scope of the patent of the present invention.

Claims (10)

1. The utility model provides an anti reinforced structure that floats of operation subway tunnel, includes tunnel lining (1), and tunnel lining is inside to be equipped with ballast bed (2), and ballast bed (2) both sides are equipped with cushion cap (3), its characterized in that: an inner reinforcing structure is arranged inside the tunnel lining (1), and an outer reinforcing structure and an anti-floating structure are arranged outside the tunnel lining; the inner reinforcing structure comprises steel sleeves (4) and reinforcing plates (5) which are arranged at intervals, the reinforcing plates (5) are welded with the steel sleeves (4), the steel sleeves (4) are tightly attached to the inner surface of the tunnel lining (1) and are fixed with the tunnel lining (1) through wall-mounted expansion bolts (6), two sides of the steel sleeves (4) are plugged by epoxy cement, and a gap between the steel sleeves (4) and the tunnel lining (1) is filled by epoxy resin; the outer reinforcing structure comprises grouting reinforcing soil bodies (7), and the grouting reinforcing soil bodies (7) are symmetrically arranged at the upper parts of the two sides of the tunnel lining (1); anti floating structure include a plurality of stock (8), establish in tunnel lining (1) bottom stock (8), inside stock (8) top anchor income railway roadbed (2), be equipped with grout body (9) around stock (8) of the following part of tunnel lining (1).

2. The operated subway tunnel anti-floating reinforcement structure according to claim 1, characterized in that: the steel sleeve (4) comprises a left arc-shaped steel plate (11) and a right arc-shaped steel plate (12), and the stiffening plate (5) comprises a left stiffening plate (13) and a right stiffening plate (14); the radian of the left arc-shaped steel plate (11) and the right arc-shaped steel plate (12) is the same as that of the inner side of the tunnel lining (1), the inner surface of the tunnel lining (1) is provided with a screw hole (24), the corresponding positions of the left arc-shaped steel plate (11) and the right arc-shaped steel plate (12) are provided with screw holes, the left arc-shaped steel plate (11) and the right arc-shaped steel plate (12) are arranged close to the inner surface of the tunnel lining (1), and the left arc-shaped steel plate (11) and the right arc-shaped steel plate (12) are connected with the tunnel lining (1) through wall-hanging expansion bolts (6) penetrating through the; the left stiffening plate (13) is welded and connected along the central axis of the left arc-shaped steel plate (11), the right stiffening plate (14) is welded and connected along the central axis of the right arc-shaped steel plate (12), the top ends of the left stiffening plate (13) and the right stiffening plate (14) are respectively provided with a connecting top plate (15), and the connecting top plates (15) at the two sides are mutually connected through split bolts (19); bottom connecting plates (18) are welded at the bottoms of the left arc-shaped steel plate (11) and the right arc-shaped steel plate (12), and the bottom connecting plates (18) are fixed on the upper surfaces of the bearing platforms (3) on the two sides through foundation bolts (17) matched with nuts.

3. The operated subway tunnel anti-floating reinforcement structure according to claim 1, characterized in that: the tunnel lining is characterized in that a plurality of grouting floral tubes (10) are arranged in the grouting reinforced soil body (7), the grouting floral tubes (10) in the grouting reinforced soil body (7) on two sides are bilaterally symmetrical, grouting holes (21) are formed in the positions, corresponding to the grouting floral tubes (10), on the left side and the right side of the tunnel lining (1), the grouting floral tubes (10) penetrate through the grouting holes (21) and are inserted into the reinforced soil body (7) on two sides of the tunnel lining (1), and the grouting holes (21) are filled with sealing materials (16) for plugging the grouting holes (21).

4. The operated subway tunnel anti-floating reinforcement structure according to claim 1, characterized in that: the anchor rod (8) comprises anchor rod main ribs (25), a plurality of anti-floating reinforcing ribs (26), a water stop steel plate (27) and a steel bar positioner (28); the anchor rod main rib (25) penetrates through the water stop steel plate (27), the bottom end of the anti-floating reinforcing rib (26) is welded at the junction of the anchor rod main rib (25) and the water stop steel plate (27), the water stop steel plate (27) is buried in the ballast bed (2) and is welded with ballast bed reinforcing steel bars (20), and the reinforcing steel bar positioner (28) is welded on the anchor rod main rib (25) of the part below the tunnel lining (1); the anchor rod main rib (25) and the anti-floating reinforcing rib (26) are respectively provided with a bending part at the top end, the bottom end of the anti-floating reinforcing rib (26) is provided with an overlap joint part parallel to the anchor rod main rib (25), the length of the bending part is at least 15 times of the diameter of the anchor rod main rib (25) or the anti-floating reinforcing rib (26), and the length of the overlap joint part is at least 55 times of the diameter of the anti-floating reinforcing rib (26).

5. A construction method of the operated subway tunnel anti-floating reinforcement structure of claim 1, characterized in that: which comprises the following steps:

1) cutting and chiseling the ballast beds and the ditches on the two sides of the subway track until shield segments are exposed;

2) constructing bearing platforms (3) at the cutting and chiseling positions of the track beds on the two sides of the subway track;

3) drilling grouting holes (21) at the upper positions of the two sides of the tunnel lining (1), driving a grouting perforated pipe (10) along the grouting holes (21) immediately after each drilling hole forms one grouting hole (21), injecting cement paste, forming a grouting reinforced soil body (7) after hardening, and then injecting waterproof concrete at the grouting hole positions to form a sealing material (16);

4) judging the reason causing the tunnel to float upwards, and calculating the anti-floating force F required by the single-ring tunnel segment_{Anti-floating}；

5) According to the buoyancy F borne by the single-ring tunnel segment_{Floating body}Calculating the axial tension design value of a single anchor rod (8), the reinforcement of the anchor rod (8), the length of the anchor rod (8) and the anchoring length of an anchoring body and the anchor rod (8);

6) drilling a track bed at the subway tunnel and setting an anchor rod (8) according to the parameters calculated in the step 5);

7) and (5) installing the steel ferrule (4) and the stiffening plate.

6. The construction method of the operated subway tunnel anti-floating reinforcement structure according to claim 5, characterized in that: the step 4) is the floating of the tunnel caused by the rising of underground water and the anti-floating force F required by the single-ring tunnel segment_{Anti-floating}The calculation steps are as follows:

4.1) calculating the effective weight G of the overlying soil column of the single-ring tunnel segment_{Soil for soil}，

4.2) calculating the dead weight G of the single-ring tunnel segment_From，

G_From＝δπ(R²-r²)γ_c；

4.3) calculation of Single Ring TunnelGroundwater buoyancy F suffered by pipe piece_{Floating body}，

F_{Floating body}＝δπR²γ_w；

4.4) calculating the required anti-buoyancy F_{Anti-floating}，

Wherein, γ_aIs the saturated volume weight of the soil body, gamma_wThe volume weight of water is shown, R is the outer diameter of the shield tunnel, h is the thickness of a soil layer on the pipeline, delta is the width of a single-ring segment, and R is the inner diameter of the shield tunnel; gamma ray_fTaking 1.2 as the safe anti-floating coefficient of the shield tunnel in the using stage; gamma ray_{Soil for soil}Taking the weight coefficient of the overburden layer on the tunnel as 1.0; gamma ray_FromTaking 1.0 as the self-weight item coefficient of the tunnel structure; gamma ray_{Anti-floating}Taking the coefficient of the anti-floating component of the anchor rod as 1.0.

7. The construction method of the operated subway tunnel anti-floating reinforcement structure according to claim 5, characterized in that: the step 4) causes the tunnel to float up for the unloading above the tunnel, and the anti-floating force F required by the single-ring tunnel segment_{Anti-floating}The calculation steps are as follows:

4.1) unloading load pd according to the coordinate (ξ) of any point at the bottom of the foundation pit_ξd_ηCalculating (x, y, z) at the tunnel axis₀) Additional stress σ of_z，

In the formula (I), the compound is shown in the specification,

upsilon is Poisson's ratio; z is a radical of₀The distance between the central line of the tunnel and the earth surface is taken as the distance; h is the excavation depth of the foundation pit;

4.2) for each ring of shield segments, assuming that the additional stress of each point at the axis is the same, the additional load F borne by each ring of shield segments due to foundation pit excavation_{Attachment(s)}Is composed of

F_{Attachment(s)}＝δRσ_z；

4.3) according to the balance relation of the forces and the design specification of the tunnel, taking F_{Anti-floating}＝F_{Attachment(s)}。

8. The construction method of the operated subway tunnel anti-floating reinforcement structure according to claim 5, characterized in that: the specific steps of the step 5) are as follows:

5.1) F calculated according to step 4_{Anti-floating}Calculating the axial tension standard value N of the anchor rod_ak，

N_ak＝F_{Anti-floating}；

5.2) according to the axial tension standard value N_akCalculating the design value N of the axial tension of a single anchor rod_t，

N_t＝γ_QN_ak，

In the formula, gamma_QTaking the load element coefficient as 1.3;

5.3) calculating the section area A of the reinforcing steel bar of the anchor rod_s，

In the formula, K_tThe safety factor of the tensile strength of the anchor rod body is increased; f. of_ykThe standard value of the tensile strength of the steel bar is;

and according to the calculated sectional area A of the anchor rod reinforcing steel bar_sDetermining the number of actual matching anchor rod reinforcing steel bars;

5.4) calculating the length L between the formation and the anchor_a1And L between anchor body and anchor rod steel bar_a2，

Selecting L_a1And L_a2The larger value is used as the anchoring length L between the anchoring body and the anchor rod (8)_a；

In the formula (f)_mgThe standard value of the bonding strength between the stratum and the anchoring grouting body is obtained; f. of_msThe standard value of the bonding strength between the steel bar and the anchoring grouting body is obtained; k is the anti-pulling safety coefficient of the anchor rod, and 2.0 is taken; d is the drilling diameter of the anchor rod anchoring section, and is taken as 150 mm; d is the diameter of the anchor rod steel bar and is determined according to actual reinforcement; n is the number of anchor rod reinforcing steel bars and is determined according to the actual reinforcing steel bars of each ring pipe sheet;the coefficient is the reduction coefficient of the bonding strength of the section of the steel bar, and the value range is between 0.6 and 0.85; psi is the influence coefficient of anchor rod anchoring length to bonding strength, takes 1.0.

9. The construction method of the operated subway tunnel anti-floating reinforcement structure according to claim 5, characterized in that: the installation steps of the anchor rod (8) in the step 6) are as follows:

6.1) chiseling concrete according to the track bed concrete chiseling trace (29), and then forming holes by using a down-the-hole hammer;

6.2) placing the anchor rod (8) which is manufactured in advance into the drilled hole, and grouting in a secondary grouting mode;

6.3) after the slurry is initially set, recharging the high-strength concrete and filling the chiseling part of the ballast bed concrete.

10. The construction method of the operated subway tunnel anti-floating reinforcement structure according to claim 5, characterized in that: the step 7) of mounting the steel ferrule (4) and the stiffening plate (5) comprises the following steps:

7.1) arranging corresponding screw holes (24) on the tunnel lining (1) according to the positions of the screw holes of the steel sleeve ring;

7.2) welding the left stiffening plate (13) on the left arc-shaped steel plate (11), welding the right stiffening plate (14) on the right arc-shaped steel plate (12), hoisting the left arc-shaped steel plate (11) and the right arc-shaped steel plate (12) to specified positions, and anchoring the left arc-shaped steel plate (11) and the right stiffening plate (14) on the tunnel lining (1) by using wall-hanging expansion bolts (6);

7.3) connecting the connecting top plates (15) of the arc-shaped steel plates at the two sides with each other by using split bolts (19);

7.4) fixing the left arc-shaped steel plate (11) and the left stiffening plate (13) and the right arc-shaped steel plate (12) and the right stiffening plate (14) on the bearing platforms (3) at two sides by adopting foundation bolts (17) respectively.

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