CN110552716A - Assembling method of circular shield tunnel lining structure - Google Patents

Abstract

The invention discloses an assembling method of a lining structure of a circular shield tunnel, which comprises the steps of calculating the position theta of the minimum normal stress according to the outer diameter D of a lining ring and the sectional stress distribution of the lining ring, and taking the position theta of the minimum normal stress as the position for installing a capping block; calculating an initial splicing segment position omega according to the position theta of the minimum positive stress, the blocking angle beta of the capping block and the blocking angle gamma of the adjacent block; placing the initial assembled duct piece at a position omega, and then assembling the duct piece along the lining ring in a one-way mode; after lining segments are assembled into a complete lining ring, assembling the next lining ring at the rear side of the lining ring, wherein the assembling direction of the lining ring is opposite to that of the previous lining ring, and realizing staggered joint assembling; and repeating until the assembly of all lining rings is completed. The method can solve the problems of insufficient construction efficiency and bearing capacity of the shield segment in the prior art, and has the advantages of wide application range, high calculation efficiency and strong design reliability.

Description

A method for assembling the lining structure of a circular shield tunnel

technical field

The invention relates to the technical field of shield tunnel lining, in particular to a method for assembling a circular shield tunnel lining structure.

Background technique

With the rapid development of my country's economy and the continuous improvement of the level of science and technology, more and more cities choose to adopt rail transit solutions to meet the travel needs of citizens and relieve urban traffic pressure. The shield method tunnel has become the first choice for building subway tunnels in major cities due to its fast construction speed, high engineering quality and low impact on the surrounding environment.

At present, most of the subway shield tunnels constructed in China adopt the form of circular section, and the lining ring is composed of a capping block, two adjacent blocks and several standard blocks. The block angle of the capping block is generally smaller than that of adjacent blocks and standard blocks.

Existing studies have found that during the isobaric loading process of the shield tunnel, the joints at both ends of the capping block open the largest, and the damage of the tunnel structure first occurs at the capping block, which shows that the capping block is the shield tunnel structure. Weak link of strength.

Since the forces around the underground tunnel structure are not equal, there are positions with the largest and smallest forces. When the shield tunnel is built in a weak stratum with a large buried depth that is not self-stable and cannot form a natural arch, if the capping block is placed at the position where the force is the largest, it is easy to cause the joints at both ends of the capping block to open too much, which will lead to shield tunneling. The water leakage problem of the shield tunnel; because the capping block is the weak link of the lining ring of the shield tunnel, it is more likely to cause damage to the tunnel when it is placed at the position with the greatest force.

Therefore, it is very necessary to choose a suitable assembly scheme to improve the safety performance of tunnel waterproofing and shield tunnel construction and operation in the whole life cycle.

Contents of the invention

Aiming at the above-mentioned deficiencies in the prior art, the present invention provides a circular shield tunnel lining structure that can solve the problem that the assembly scheme of the shield lining ring in the prior art is likely to cause excessive force on the capping block structure and affect the service life assembly method.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A method for assembling a circular shield tunnel lining structure is provided, which includes the following steps:

S1, calculate the position θ of the minimum normal stress according to the cross-sectional stress distribution of the outer diameter D of the lining ring and the lining ring, and use the position θ of the minimum normal stress as the position where the capping block is installed;

S2. Calculate the initial assembled segment position ω according to the position θ of the minimum normal stress, the block angle β of the capping block, and the block angle γ of the adjacent block;

S3. Place the initial assembled segment at position ω, and then assemble the segment along the lining ring in one direction;

S4. After the lining segment is assembled into a complete lining ring, the next lining ring is assembled on the rear side of the lining ring, and the assembling direction of the lining ring is opposite to that of the previous lining ring, so as to realize the staggered seam assembly;

S5. Step S4 is repeated until the assembly of all lining rings is completed.

Further, the calculation formula of the minimum normal stress is:

θ＝122.8031+1.8663D+0.0968p ₁ +0.0332q ₁ -0.1151q ₂ -0.168p _k

Among them, p ₁ is the vertical load, q ₁ is the top lateral pressure, q ₂ is the bottom lateral pressure, p _k is the formation resistance, p ₁ , q ₁ , q ₂ and p _k are the cross-sectional stress distribution of the lining ring.

Further, the vertical load includes the upper vertical load and the lower vertical load, and the calculation method _of the vertical load p1 is:

p ₁ =p _e1 +p _w1

Among them, p _e1 is the upper soil pressure, p _w1 is the upper water pressure.

Further, the calculation method of the top lateral pressure _q1 is:

q ₁ =λp _e1 +p _w1

Among them, λ is the soil lateral pressure coefficient.

Further, the calculation method of the bottom lateral pressure q2 is:

Among them, ρ is the density of the soil, t is the thickness of the segment, and p _w2 is the pressure of the lower water body.

Further, the calculation method of formation resistance p _k is:

Among them, k is the formation resistance coefficient, R is the segment center radius, g is the acceleration due to gravity, η is the bending stiffness, E is the modulus of elasticity, and I is the moment of inertia of the segment.

Further, the calculation method of the initial assembled segment position ω is:

Further, the lining ring includes a capping block, two adjacent blocks and several standard blocks.

Further, the positions of the two capping blocks of adjacent two lining rings are mirror symmetrical about the vertical line passing through the center of the lining ring.

The main beneficial effects of the assembly method of the above-mentioned circular shield tunnel lining structure provided by the present invention are:

In this method, by placing the capping block at the position of the minimum normal stress of the lining ring, the unfavorable mechanical conditions that cause damage to the capping block can be reduced to the greatest extent, and the safety performance during the construction and operation period of the shield tunnel can be improved; The location of the block, the position of the block angle of the capping block and the adjacent block, and the selection of the position of the initial assembly block can ensure the stability and efficiency of the assembly of the lining ring.

The longitudinal rigidity of the tunnel structure is improved by assembling the lining segments in one direction and staggering the lining rings. And the assembly method is simple, without adding extra workload, which helps to improve efficiency under the premise of ensuring safety.

Description of drawings

Fig. 1 is a schematic diagram of the assembly method of the circular shield tunnel lining structure of the present invention.

Figure 2 is a schematic diagram of the cross-sectional stress distribution of the tunnel lining ring.

Figure 3 is a schematic diagram of clockwise assembly of the lining ring.

Figure 4 is a schematic diagram of counterclockwise assembly of the lining ring.

Figure 5 is a schematic diagram of the stratum structure.

Among them, 1. Capping block, 2. Adjacent block, 3. Standard block, 4. Lining ring, 5. Initially assembled segments.

Detailed ways

The present invention will be further described below in conjunction with accompanying drawing:

As shown in Figure 1, it is a schematic diagram of the assembly method of the circular shield tunnel lining structure.

The assembling method of circular shield tunnel lining structure of the present invention comprises the following steps:

S1. Calculate the position θ of the minimum normal stress according to the outer diameter D of the lining ring 4 and the cross-sectional stress distribution of the lining ring 4, and use the position θ of the minimum normal stress as the position where the capping block 1 is installed.

The location of the minimum normal stress θ is within the safest range of hoop stress under the design load.

Specifically, the cross-sectional stress distribution includes vertical load p ₁ , top lateral pressure q ₁ , bottom lateral pressure q ₂ and formation resistance p _k , as shown in Fig. 2, the calculation method of cross-sectional stress distribution is as follows:

S1-1. The calculation method of the minimum normal stress position θ is:

θ＝122.8031+1.8663D+0.0968p ₁ +0.0332q ₁ -0.1151q ₂ -0.168p _k

Wherein, the vertical load includes the upper vertical load p ₁ and the lower vertical load p ₂ .

Generally, the upper vertical load p ₁ and the lower vertical load p ₂ are equal in magnitude. Therefore, take the upper vertical load _p1 for analysis. _The calculation method of p1 is:

p ₁ =p _e1 +p _w1

Among them, p _e1 is the upper soil pressure, p _w1 is the upper water pressure, both p _e1 and p _w1 are calculated according to the soil and water environment where the tunnel is located.

In the actual calculation, p _e1 is calculated according to the specific layering of the soil:

p _e1 ＝P _vc ＝∑h _i ρ _i

h _i is the thickness of each layer of soil, ρ _i is the density of each layer of soil.

p _w1 is calculated according to the water table depth H _w :

Among them, t is the thickness of the segment, and _ρw is the density of water.

S1-2. The calculation method of top lateral pressure _q1 is:

q ₁ =λp _e1 +p _w1

Among them, λ is the soil lateral pressure coefficient.

S1-3. The calculation method of bottom lateral pressure _q2 is:

Among them, ρ is the density of the soil body, and p _w2 is the pressure of the lower water body, and its calculation method is:

S1-4. The calculation method of formation resistance p _k is:

Among them, k is the formation resistance coefficient, R is the segment center radius, g is the gravitational acceleration, η is the bending stiffness, which is selected by referring to the "Tunnel Standard Specification", E is the elastic modulus, and I is the segment moment of inertia.

S2. Calculate the position ω of the initial assembled segment 5 according to the position θ of the minimum normal stress, the block angle β of the capping block 1, and the block angle γ of the adjacent block 2.

The initial assembled segments 5 are generally standard blocks 3 . The calculation method of the position ω of the initial assembled segment 5 is:

S3. Put the initial assembled segment 5 at the position ω, and then assemble the segment along the lining ring in one direction.

Use the internal segment assembly equipment of the shield machine to accurately place the initial assembled segment 5 in place, then assemble the lining ring in one direction clockwise or counterclockwise, and finally assemble the capping block 1 segment.

S4. After the lining segment is assembled into a complete lining ring, the next lining ring is assembled on the rear side of the lining ring, and the assembling direction of the lining ring is opposite to that of the previous lining ring, so as to realize staggered seam assembly.

Wherein, the lining ring 4 includes a capping block 1 , two adjacent blocks 2 and several standard blocks 3 . And two capping block 1 positions of adjacent two lining rings 4 are mirror-symmetrical about the vertical line that passes lining ring 4 center, to guarantee the accuracy of lining segment assembling.

S5. Step S4 is repeated until the assembly of all lining rings is completed.

The longitudinal rigidity of the tunnel structure is improved by repeated staggered assembly. And the assembly method is simple, without adding extra workload, which helps to improve efficiency while ensuring safety.

The following specific calculation example illustrates the calculation method of the minimum normal stress position θ in this patent:

The stratum structure is shown in Fig. 5, where the buried depth H of the tunnel is 13.6m, the segment outer diameter D is 6.2m, the segment width B is 1.2m, the segment thickness t is 0.35m, and the segment weight γ _c is 26kN/m ³ ; the central angle β corresponding to the capping block is 21.5°, the central angle γ corresponding to the adjacent block is 68°, and the central angle corresponding to the standard block is 67.5°; the elastic modulus E is 3.45e ⁴ MPa, and the water level is H _w is 8.12m, water gravity γ _w is 10kN/m ³ , segment center radius R is 2.925m, and gravitational acceleration g is 10m/s ² . The physical and mechanical parameters of the formation are shown in Table 1.

Table 1 Formation physical and mechanical parameters

S1, first calculate the cross-sectional stress distribution of the lining ring 4:

The segment moment of inertia I is:

Since H=13.65m>1D～2D, Terzaghi formula can be used, and the road vehicle load p ₀ is taken as: p ₀ =10kPa.

S1-1. First, the upper vertical load p ₁ . Since the soil layer is multi-layered, the method of layering is adopted and calculated layer by layer from the first layer to the sixth layer. The calculation formula is:

Taking the first layer as an example, in the formula, P _vci is the loosening earth pressure, B ₁ is the width of the loosening zone, K ₀ is the ratio of horizontal earth pressure to vertical earth pressure, which is generally taken as 1; is the internal friction angle of the soil, c ₁ is the adhesion force of soil, c=0; γ ₁ is the unit volume mass of soil, γ=19kN/m ³ ; H ₁ is the thickness of overlying soil, H=2.46m; p ₀ is the upper load, that is, the road vehicle load , p ₀ =10kPa; R ₀ is the outer radius of the segment, R ₀ =3m.

Substituting the data into the above formula can get:

Calculate the loosening zone width B _i and loosening earth pressure P _vci of each layer in turn, and the results are shown in Table 2:

Table 2 Width of loose belt and loose soil pressure of each layer

Therefore, the natural equilibrium arch height h ₀ is: Since h ₀ =4.95m<2D=12.4m, h ₀ is taken as 12.4m; the total pressure P _vc of the original soil layer is: P _vc =∑h _i γ _i =182.51kPa. Where: ∑h _i =h ₀ =12.4m.

Since the upper vertical pressure p ₁ is: p ₁ =p _e1 +p _w1 , where the upper earth pressure: p _e1 =p _vc =182.51kPa, the upper water pressure: Therefore, the upper vertical pressure p1 is: p ₁ =p _e1 +p _w1 =265.46kPa.

S1-2. Top lateral pressure q ₁ is: q ₁ =λp _e1 +p _w1 =0.2×182.51+82.95=119.45kPa.

S1-3. Bottom lateral pressure q ₂ :

S1-4. Formation resistance p _k :

Substituting the above cross-sectional stress distribution into the calculation formula of the minimum normal stress position θ, we get:

θ=122.8031+1.8663D+0.0968p ₁ +0.0332q ₁ −0.1151q ₂ −0.168p _k =112.26°.

S2. Calculate the position ω of the initial assembled segment 5 according to the position θ of the minimum normal stress, the block angle β of the capping block 1, and the block angle γ of the adjacent block 2:

S3. Put the initially assembled segment 5 in position, and then assemble the segments unidirectionally along the lining ring.

S4, after the lining segments are assembled into a complete lining ring 4, the next lining ring 4 is assembled on the rear side of the lining ring 4, and the assembling direction of the lining ring 4 is opposite to that of the previous lining ring 4, so as to realize the staggered seam assembly.

S5. Step S4 is repeated until the assembly of all the lining rings 4 is completed.

The specific embodiments of the present invention are described above so that those skilled in the art can understand the present invention, but it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art, as long as various changes Within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are included in the protection list.

Claims (9)

1. A splicing method of a circular shield tunnel lining structure is characterized by comprising the following steps:

S1, calculating the position theta of the minimum normal stress according to the outer diameter D of the lining ring and the cross-sectional stress distribution of the lining ring, and taking the position theta of the minimum normal stress as the position for installing the top sealing block;

s2, calculating an initial splicing segment position omega according to the position theta of the minimum normal stress, the blocking block angle beta of the capping block and the blocking block angle gamma of the adjacent block;

s3, placing the initial assembled duct piece at the position omega, and then assembling the duct piece along the lining ring in a one-way mode;

S4, after lining segments are assembled into a complete lining ring, assembling the next lining ring at the rear side of the lining ring, wherein the assembling direction of the lining ring is opposite to that of the previous lining ring, and realizing staggered assembly;

And S5, repeating the step S4 until the assembly of all lining rings is completed.

2. The method for assembling the circular shield tunnel lining structure according to claim 1, wherein the calculation formula of the minimum normal stress is as follows:

θ＝122.8031+1.8663D+0.0968p₁+0.0332q₁-0.1151q₂-0.168p_k

Wherein p is₁For vertical loading, q₁Top lateral pressure, q₂As bottom lateral pressure, p_kas resistance of the formation, p₁、q₁、q₂and p_kis the cross-sectional stress distribution of the lining ring.

3. The method for assembling the lining structure of the circular shield tunnel according to claim 2, wherein the vertical loads comprise an upper vertical load and a lower vertical load, and the vertical load p is p₁The calculation method comprises the following steps:

p₁＝p_e1+p_w1

Wherein p is_e1is the pressure of the upper soil body, p_w1Is the upper water body pressure.

4. The method for assembling a circular shield tunnel lining structure according to claim 2, wherein the top lateral pressure q is₁The calculation method comprises the following steps:

q₁＝λp_e1+p_w1

wherein, the lambda is the lateral pressure coefficient of the soil body.

5. The method for assembling the circular shield tunnel lining structure of claim 4, wherein the bottom lateral pressure q2 is calculated by the following method:

Wherein rho is the soil density, t is the thickness of the pipe piece, and p_w2The pressure of the lower water body.

6. The method for assembling a circular shield tunnel lining structure according to claim 5, wherein the formation resistance p is_kThe calculation method comprises the following steps:

Wherein k is the formation resistance coefficient, R is the central radius of the pipe piece, g is the gravity acceleration, eta is the bending rigidity, E is the elastic modulus, and I is the inertia moment of the pipe piece.

7. The method for assembling the circular shield tunnel lining structure according to claim 6, wherein the method for calculating the initial assembling segment position ω is as follows:

8. The method for assembling a circular shield tunnel lining structure according to claim 1, wherein the lining ring comprises one capping block, two adjacent blocks and a plurality of standard blocks.

9. The method for assembling the circular shield tunnel lining structure of claim 1, wherein the positions of the two capping blocks of the two adjacent lining rings are mirror-symmetrical with respect to a vertical line passing through the centers of the lining rings.