JPH08199990A - Precast member and joint structure thereof - Google Patents

Abstract

PURPOSE: To reduce stress concentration to fastening parts of precast members and bolts in a shield segment or the like and prevent the precast members and auxiliary members from breaking at an earthquake and during the construction and increase the safety of the tunnel or the like. CONSTITUTION: An arcuate recess 7 for dispersion of stresses, longitudinally extending on the joint face and an arcuate protrusion 8 for dispersion of stresses longitudinally extending likewise, are provided respectively at the joint face 2 between mutual rings of segments 2 or at the joint face between segments. When these recess and protrusion are fitted to each other, a clearance 9 is generated between them. When a larger shearing load than a designed strength due to the fastening force of bolt joints 5 acts on the segments, a fine sliding movement within a specified range is allowed in the clearance between the recess and protrusion and on the mutual joint faces.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precast member such as a shield segment which is acted upon by an external pressure or an internal pressure due to earth pressure, water pressure or the like, and its joint structure.

[0002]

2. Description of the Related Art Conventional general shield segments are
The segments are tightened with bolts to apply an axial force to each joint surface, and the shear force generated by the tunnel design load (positional pressure, water pressure, etc.) is countered by the friction force of the joint surface. That is, the joint surfaces and the bolts and nuts have strength and tightening force that maintain the design yield strength against the shear load expected after completion.

FIG. 12 is a model diagram illustrating load transfer between segments by a bolt joint, and 51 is a segment,
Reference numeral 52 denotes a bolt joint, 53 denotes an inter-segment joint portion tightened by the bolt joint 52, and 54 denotes an inter-ring joint portion similarly tightened by the bolt joint 52. In this case, since the inter-segment joint portion 53 has a function of transmitting the axial compression force, the axial tension force, the shearing force, and the bending force to the adjacent segment 51, the load applied to the segment 51 (tunnel) is mainly the tunnel. It is transmitted in the cross-sectional direction. Further, the inter-ring joint portion 54 secondarily transmits a load by the frictional force between the segment end faces in the tunnel axis direction and the segment end faces.

However, the joint structure using the bolt joints opposes the work load acting in the tail of the shield machine at the time of constructing the shield by the frictional force of the joint surface based on the bolt tightening force. Since the design value corresponds to the expected shear load later, it resists the excessive shearing force during construction caused by the jack thrust when the shield machine is propelled or the competition of each member in the tail. It is not possible, and slip occurs on the joint surface of each other. However, in the case of bolted joints, the actual condition is that the shear load generated during construction must depend on the shear strength of the bolt.
Therefore, a shear load is concentrated on the bolt, and a large stress is concentrated on the segment portion around the bolt, and there is a problem that the segment main body and the attached member under construction are damaged (cracking, peeling of concrete, etc.) from the portion.

Further, in curved construction, a large lateral force (shearing force of the ring joint) acts on the curved portion of the completed tunnel as the shield machine is propelled, and this force is sheared by the bolt tightening force. When it becomes larger than the proof stress,
There has been a problem that slippage occurs between the joints of the segments after the construction and excessive stress is generated around the bolts in the same manner as described above, and the segment body and the attached members after the construction are damaged.

On the other hand, Japanese Utility Model Publication No. 6-14300 discloses a joint structure with a tenon. FIG. 11 shows the main part thereof, in which one end of one segment 61a has a trapezoidal groove 62a having a trapezoidal cross section on both sides and the other end of the segment 61b has a trapezoidal ridge 62 having the same trapezoidal shape.
b is provided, and the concave groove 62a and the ridge 62b are provided as cushioning material
They are fitted together with 2c interposed.

FIG. 13 is a model diagram illustrating load transfer between segments by a tenon joint, where 61 is a segment,
62 is a joint with tenon by concave and convex fitting, 63 is a joint part between tenon with tenon joined by the tenon joint 62, 64
Shows a joint part between tenon rings with a tenon joint 62 similarly. In this case, the tenon-joint segment 63 can transmit the axial compressive force and the shearing force, but cannot transmit the axial tensile force and the bending force. Therefore, by transmitting as a shearing force to the adjacent segment 61 by the tenon (concave-fitting) in the joint part 64 with a tenon ring,
The load will be taken over by the transmission path indicated by the filled arrow.

Unlike the bolt joint, the joint with a tenon does not have the above-mentioned problems due to the concentration of stress on the bolt, but since the tenon of the unevenness directly resists the shearing force generated by the load, the joint and the construction are carried out. If the shearing force exceeds the design in, the tenon will be damaged. Further, the cushioning material as shown in FIG. 11 corrects an error such as a manufacturing error, and even if it is used, the tenon portion cannot be prevented from being damaged.

[0009]

The object of the present invention is to utilize the advantages of the bolt joint structure as they are and reduce the stress concentration on the tightening members such as bolts, which is the drawback thereof, to reduce the stress during an earthquake or during construction. Preventing damage to precast members (shield segments, etc.) and auxiliary members to improve safety of tunnels, etc., and to improve economy and workability by thinning precast members and simplifying joints. It is in.

[0010]

SUMMARY OF THE INVENTION The present invention is basically a bolt joint structure, that is, the joint surfaces of precast members have at least a design strength against a shear load due to the tightening force of tightening members such as bolts. The structure is joined so as to maintain it, but the following constitution is added to this.

That is, a stress dispersion joint portion is provided on the joint surfaces of the precast members so as to be slidably fitted in the width direction of the precast members to disperse the stress. One of the fitting portions for stress dispersion to be fitted is a concave portion that is recessed in an arc shape and extends in the longitudinal direction of the joint surface, and the other is a convex portion that projects in an arc shape and also extends in the longitudinal direction. Is a fitting state that allows sliding within a minute predetermined range between the concave portion and the convex portion and the mutual joint surfaces when a shear load larger than the design proof strength due to the tightening force of the tightening member is applied. For example, when the curvature of the stress-dispersing concave portion is set to be slightly larger than the curvature of the stress-dispersing convex portion, a gap is formed between the concave portion and the convex portion when they are fitted to each other, and a small predetermined range is formed by the gap. Only allow sliding. In this case, the gap between the stress-dispersing concave portion and the stress-dispersing convex portion is set smaller than the gap between the hole provided in the precast member for inserting the tightening member and the tightening member.

If the depth of the stress-dispersing concave portion and the height of the stress-dispersing convex portion are set such that the curved-surface top portion of the stress-dispersing convex portion is in pressure contact with the curved-surface trough portion of the stress-dispersing concave portion, the convex portion and the concave portion are separated from each other. Even if they are eccentric with respect to each other, an aligning action that tries to align their centers occurs.

[0013]

Since the joint structure of the present invention is basically the same as the bolt joint structure, when the precast member is a shield segment, the load transmission between the segments is the same as in FIG. However, the load transmission is performed while distributing the stress without concentrating the stress on the bolt.

That is, the segments are joined to each other so as to maintain the design proof stress due to the frictional force of the joint surface generated by the tightening force of the bolt against the shearing load, but the shearing load exceeding this frictional force is applied. At times, the stress-dispersing convex portion and the stress-dispersing concave portion are loose, so that the joint surfaces of the joints slide by a very small predetermined range. This releases the stress accumulated in the precast member due to the frictional force and the shearing force of the joint surface, and prevents the precast member from being damaged. The unevenness for stress distribution, in which the curvature of the arcuate surface is different, moderates the impact of the sliding of the joint surface and limits the amount of sliding to a minute range. This practically prevents the displacement of the joint surfaces, prevents damage to the precast member, and at the same time reduces stress concentration on tightening members such as bolts.

[0015]

Embodiments of the present invention applied to shield segments will be described below.

1 and 2 show an example of the shield segment according to the present invention. Since this segment 1 has an RC structure in which a rectangular shape is curved, the long side end faces of the segments are joint rings 2 and the short side end faces of the segment joint faces 3 are for joining the segments by bolt joints. ,
Each of the joint surfaces 2 and 3 is provided with a plurality of bolt insertion holes 4. In this example, since the C-shaped bolt joint 5 is used as shown in FIG. 4, the bolt insertion hole 4 is curved between the inner surface of the segment 1 and the joint surface 2 or 3 as shown in FIG. Further, the bolt insertion hole 4 has a diameter such that the C-shaped bolt joint 5 can be penetrated with a slight margin. A bolt box 6 is provided on the inner surface of the segment 1 for each bolt insertion hole 4.

On the joint surface 2 between both rings of each segment 1, a stress dispersion recess 7 is formed which is recessed in an arc shape and extends in the longitudinal direction.
And a convex portion 8 for stress dispersion that protrudes in an arc shape and extends in the longitudinal direction.
And the joint surface 3 between both segments are also provided with the same stress dispersion concave portion 7 and stress dispersion convex portion 8, respectively. In the case of this example, the convex portion 8 is integrally molded with concrete. The width of the concave portion 7 and the convex portion 8 is normally 1/2 of the width of the joint surfaces 2 and 3 of the segment 1.
Or about 1/3, but its size, curvature and concave portion 7
And the height of the convex portion 8 are determined by, for example, computer simulation using contact analysis by a finite element model.

When the segments 1 are joined together, the inter-ring joint surface 2 and the inter-segment joint surface 3 are joined together.
Are contacted with each other to fit the stress-dispersing concave portion 7 and the stress-dispersing convex portion 8 to each other, and the curvature of the curved surface of the concave portion 7 is adjusted so that a gap is formed between the concave portion 7 and the convex portion 8 in the fitted state. Is slightly larger than the curvature of the curved surface of the convex portion 8. That is, when the curved surface is an arc surface, the radius of the curved surface of the concave portion 7 is larger than the radius of the curved surface of the convex portion 8 as shown in FIG.
However, the depth of the concave portion 7 and the height of the convex portion 8 are equal to each other, and when the inter-ring joint surface 2 is in contact with each other and the inter-segment joint surface 3 is in contact with each other,
The curved surface valley portion 7a of the concave portion 7 and the curved surface top portion 8a of the convex portion 8 are in contact with each other, and usually a slight gap is provided on both sides of the contact portion (the width direction of the joint surfaces 2 and 3) as shown in FIGS. 9 is formed.

Therefore, since the concave portion 7 and the convex portion 8 have different curvatures, there is a loose fitting state, and there is a margin for sliding in the width direction of the joint surfaces 2 and 3 by the gap 9.
However, since the gap 9 is smaller than the gap 10 formed between the bolt of the bolt joint 5 and the bolt insertion hole 4, the ring-to-ring joint surface 2 of each of the segments 1 is formed.
Or, even if the inter-segment joint surface 3 is displaced in the width direction and the concave portion 7 and the convex portion 8 reach the sliding limit as shown in FIG. 7, a gap between the bolt of the bolt joint 5 and the bolt insertion hole 4 is formed. 10 remains slightly.

The concave portions 7 and the convex portions 8 have circular arc surfaces with a uniform radius, and as shown in FIG.
It may be a curved surface having different radii for each step or an elliptic curved surface as shown in FIG. Further, in the example of the drawing, the bolt insertion holes 4 are provided at substantially the same positions as the concave portions 7 and the convex portions 8 on the inter-ring joint surface 2 and the inter-segment joint surface 3, but the positions apart from the concave portions 7 and the convex portions 8 are provided. May be provided.
In addition, in FIG. 3, FIG. 4 and FIG. 5, 11 is a seal member.

A segment 1 as described above in FIGS.
The joint structure of this invention which joined each other is shown. In the tunnel axial direction, the ring-to-ring joint surfaces 2 are brought into contact with each other, and the recesses 7 and the protrusions 8 are fitted into each other, and in the tunnel cross-sectional direction, the segment-to-segment joint surfaces 3 are brought into contact with each other. The concave portion 7 and the convex portion 8 are fitted to each other, for example, the C-shaped bolt joint 5 is inserted into the bolt insertion hole 4 and tightened, and the tightening force joins them so that their joint surfaces maintain the design yield strength. At this time, even if the centers of the concave portion 7 and the convex portion 8 are eccentric, due to the tightening force of the bolt joint 5,
The curved peak 8a of the convex portion 8 is the deepest curved valley 7a of the concave portion 7.
Since the centering action of sliding toward the center of the concave portion 6 and the center of the convex portion 8 occurs, the positions of the segments 1 are automatically corrected. This occurs even after construction.

After joining the segments 1 in this way, when a shear load exceeding the design proof strength due to the tightening force of the bolt joint 5 acts on their joint surfaces, the recess 7
Since a gap 9 is formed between the bolt 8 and the convex portion 8 and a gap 10 is formed between the bolt of the bolt joint 5 and the bolt insertion hole 4, their joint surfaces slide. In this case, since the curved surface of the concave portion 7 and the curved surface of the convex portion 8 are arcuate surfaces, as the curved surface of the convex portion 8 slides along the curved surface of the concave portion 7, the stress is absorbed so as to be radially dispersed. To be done. Further, the gap 9 between the concave portion 7 and the convex portion 8 is the gap 10 between the bolt and the bolt insertion hole 4.
Because it is smaller, the sliding limit is reached between the concave portion 7 and the convex portion 8 before the bolt contacts the wall surface of the bolt insertion hole 4, as shown in FIG. 7. Then, after that, the shear load is transmitted even in the fitting portion between the concave portion 7 and the convex portion 8 in the state where the gap 10 between the bolt and the bolt insertion hole 4 slightly remains, so that the stress concentration on the bolt can be prevented. .

In the above embodiment, the segment 1
Although the convex portion 8 is integrally molded with concrete as the RC structure, it may be fitted into the fixed concave portion 1a of the RC structure or steel segment main body as made of rubber as shown in FIG. In this case, since the convex portion 8 itself has elasticity, when it is fitted into the stress-dispersing concave portion 7 of the opponent segment 1, even if a gap is not formed between the convex portion 8 and the opposing segment 1, the joint surface has a predetermined range. Can be allowed to slide. In addition, the segment body is R
As the C structure, the protrusions 8 may be made of metal, or both the segment body and the protrusions 8 may be made of metal. The same applies to the recess 7. Further, although the C-shaped bolt joint is used as the tightening member, a linear bolt joint or an anchor bolt may be used.

The present invention can be applied not only to the shield segment but also to other precast members (vertical tunnels, box culverts, piers, etc.) obtained by dividing a circle or a square into a precast member.

[0025]

According to the present invention, when a shearing load exceeding the design proof stress due to the tightening force of a bolt is applied, the stress is radially distributed by the sliding between the stress-dispersing convex portion and the stress-dispersing concave portion. After the protrusion and the recess reach the sliding limit, the shear load is transmitted to the fitting portion between the protrusion and the recess, so that the stress concentration on the bolt can be reduced. Therefore, it is possible to prevent the precast member and the auxiliary member from being damaged during the construction, and to improve the economical efficiency and the workability by thinning the precast member and simplifying the joint portion.

If the depth of the stress-dispersing concave portion and the height of the stress-dispersing convex portion are set so that the curved surface top portion of the stress-dispersing convex portion is in pressure contact with the curved-surface trough portion of the stress-dispersing concave portion, the convex portion and the concave portion are separated from each other. Even if they are eccentric to each other, an aligning action is made to try to align their centers. Therefore, even if the centers of these convex portions and concave portions are eccentric, the positions of the segments can be automatically corrected.

[Brief description of drawings]

FIG. 1 is a side view of an example of a shield segment according to the present invention.

FIG. 2 is an inner surface view of the above.

FIG. 3 is a cross-sectional view showing a state before segment joining of an embodiment of the joint structure according to the present invention.

FIG. 4 is a cross-sectional view of the above joined state.

5 is a cross-sectional view of a portion different from FIG.

FIG. 6 is a diagram showing a size relationship between a curved surface of a stress dispersion concave portion and a curved surface of a stress dispersion convex portion.

FIG. 7 is a cross-sectional view showing a state where the stress-dispersing concave portion and the stress-dispersing convex portion have reached the sliding limit.

FIG. 8 is a diagram showing an example in which the radius of the curved surface of the stress-dispersing concave portion and the radius of the curved surface of the stress-dispersing convex portion are different by two steps on both sides in the width direction.

FIG. 9 is a diagram showing an example in which the curved surface of the stress dispersion concave portion and the curved surface of the stress dispersion convex portion are elliptical.

FIG. 10 is a cross-sectional view showing another example of the present invention in which the stress-dispersing convex portion is made of rubber.

FIG. 11 is a cross-sectional view of a conventional tenon joint structure.

FIG. 12 is a model diagram illustrating load transfer between segments by a bolt joint.

FIG. 13 is a model diagram illustrating load transfer between segments by a tenon joint.

[Explanation of symbols]

 1 segment 2 inter-ring joint surface 3 inter-segment joint surface 4 bolt insertion hole 5 bolt joint 6 bolt box 7 stress dispersion concave portion 7a curved surface of stress dispersion concave portion 8 stress dispersion convex portion 8a stress dispersion convex surface Top 9 Gap between stress-dispersing concave portion and stress-dispersing convex portion 10 Gap between bolt and bolt insertion hole

Claims (5)

[Claims] 1. A precast member in which mutual joint surfaces are tightened and joined with a tightening member such as a bolt, and for stress dispersion in which the mutual joint surfaces are slidably fitted in the width direction to disperse stress. A precast member having a joint portion. 2. A precast member, wherein a plurality of precast members are tightened by tightening members such as bolts, and the joint surfaces of the precast members are joined to each other so as to at least maintain a design resistance against the shear load due to the tightening force of the tightening members. In the joint structure,
Mutual joint surfaces of the plurality of precast members are provided with a stress-dispersing concave portion that is recessed in an arc shape and extends in the longitudinal direction of the joint surface and a stress-dispersing convex portion that protrudes in an arc shape and also extends in the longitudinal direction. The convex portion and the concave portion and the convex portion, when the shear load larger than the design proof stress is applied, in a fitting state that allows only a small predetermined range of sliding on the joint surface, Joint structure for precast members. 3. The stress-dispersing concave portion has a curvature slightly larger than that of the stress-dispersing convex portion, and when the concave portion and the convex portion are fitted to each other, a gap is formed between them, and the gap causes a minute gap. The joint structure of the precast member according to claim 2, wherein the sliding is allowed only in a predetermined range. 4. A gap between the stress-dispersing concave portion and the stress-dispersing convex portion is smaller than a gap between the hole and the tightening member provided in the precast member for inserting the tightening member. Item 3. A joint structure for a precast member according to item 3. 5. The relationship between the depth of the stress-dispersing concave portion and the height of the stress-dispersing convex portion is such that the curved-surface top portion of the stress-dispersing convex portion is in pressure contact with the curved-surface valley portion of the stress-dispersing concave portion. The joint structure for a precast member according to claim 2, 3 or 4.