JP3499005B2 - Tail seal structure and shield method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a tail seal structure for a shield machine and a shield construction method. More specifically, when the gap thickness between the outer surface of the shield tail portion and the inner surface of the skin plate changes, A water-stop structure to prevent groundwater and sediment from flowing into the shield machine from the gap, and a seismic isolation layer between the outer surface of the lining and the ground surface near the boundary between the hard and soft layers. Regarding the shield construction method to be formed.

[0002]

2. Description of the Related Art Conventionally, when constructing a tunnel in a city or its suburbs, a shield construction method has been adopted.
Such shield tunnels are now required to have seismic resistance so that they can withstand the ground displacement of a large earthquake of the Kanto Earthquake, that is, the ground displacement ranging from 25 cm to 30 cm. Therefore, in order to withstand the deformation of the surrounding ground at the time of a large earthquake and to follow the deformation accompanying the subsidence of the shield tunnel, a flexible joint, for example, a flexible joint, may be used between the rings of the shield segment as the lining part. Flexible segments and elastic ring bolts were sometimes provided.

In the former method of using a flexible segment ring, the amount of ground displacement suddenly changes at the time of an earthquake near the boundary between the hard stratum and the soft stratum, so that the flexible segment ring is accurately installed near this boundary. Is required. However, it is difficult to accurately detect the boundary portion, and therefore, there are problems that the construction cost increases because a large number of flexible segment rings are installed around the boundary.

Further, in the latter method of providing the elastic ring bolt, when the surrounding ground is largely deformed at the time of an earthquake, the displacement amount cannot be absorbed, so that the secondary lining is provided.
In this secondary lining, it is necessary to provide a secondary lining concrete expansion joint for each segment ring, and there is a problem that the construction cost increases.

Therefore, in the vicinity of the boundary between the hard formation and the soft formation, seismic isolation material such as bentonite or urethane is injected into the gap between the segment outer surface and the ground surface (hereinafter referred to as "tail void"). It has been proposed to form a seismic isolation layer that absorbs external pressure and absorb the displacement of the ground during the earthquake to mitigate the effect on the tunnel. However, a normal tail void is, for example, only about 5 cm in a tunnel with a diameter of 5 m, and if this tail void is filled with seismic isolation material,
It is not possible to fully absorb the amount of ground displacement during a large earthquake ranging from 25 cm to 30 cm. Therefore, a section forming a seismic isolation layer (hereinafter referred to as “seismic isolation section” in the present specification)
Say. ) Various devices and methods have been proposed for thickening the tail void, and as one of them, in the seismic isolation section, a segment (for example, ductile) thinner than a normal segment (for example, RC segment) used for other sections is used. There is a method of forming a seismic isolation layer having a sufficient thickness in the ground side region, that is, in the tail void of the thin segment by using the segment or the steel segment) and the difference in the segment thickness.

[0006]

Normally, the gap between the inner surface of the skin plate and the outer surface of the segment (hereinafter referred to as "tail clearance" in this specification) is shown in FIG.
As shown in (a) and (b), a plurality of tail seal materials are provided, and there is a wire brush type tail seal material. Special high-viscosity grease is injected between the wire brush type tail seals to prevent groundwater, soil, and backfill injectant from entering the shield machine. However, when the seismic isolation layer is formed by the method described above, a thin segment is used in the seismic isolation section, so the outer circumference of the segment becomes smaller than other sections, the tail clearance expands, and the length is short with ordinary tail seal materials. There is a problem that it is difficult to prevent the intrusion of groundwater, soil, and backfill injection material.

Further, in order to allow the tail seal material to be commonly used for both the normal segment and the thin segment, even if it is made long, it is required to flexibly deform and seal the tail clearance when the tail clearance is short. When the tail clearance is long, the strength to withstand the increased pressure of groundwater, soil, and backfill injection material on the ground side is required, so there is no reality of a tail seal material with such material characteristics. Is.

The present invention has been made to solve the above problems, and an object thereof is to increase the tail clearance of a shield machine when a tail segment is thickened using a thin segment to form a seismic isolation layer. Even if it shrinks, this tail clearance will be reliably sealed, and groundwater, earth and sand,
It is an object of the present invention to provide a tail seal structure capable of preventing backfilling injection material and seismic isolation material from flowing into a shield machine.

Another object of the present invention is to provide groundwater, soil, sand, backfill in the case of forming a seismic isolation layer by using a thin segment to thicken a tail void near the boundary between a hard layer and a soft layer. An object of the present invention is to provide a shield construction method capable of preventing the injected material and the seismic isolation material from flowing into the shield machine.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in view of the above object, and its gist is in the case where the gap thickness between the outer surface of the lining portion of the shield tail portion and the inner surface of the skin plate changes. The water-stopping structure for preventing groundwater, earth and sand, backfill material, and seismic isolation material from flowing into the shield machine from the gap, which is provided along the entire circumference of the inner surface of the skin plate of the tail portion. With a tail seal,
An inner skin plate which is in contact with the first tail seal and is provided all around the inner side thereof, a fixing means for fixing the inner skin plate, and the lining portion provided all around the inner surface of the inner skin plate. And a second tail seal in contact with the tail seal structure.

In the tail seal structure of the present invention, the fixing means for fixing the inner skin plate is, for example, a plate material such as a steel plate which is connected to the inner surface of the skin plate at an end of the inner skin plate or at another suitable place. There are means for fixing by welding or screwing. At this time, a plate material such as a steel plate may be provided in a ring shape that is continuous over the entire circumference between the skin plate and the inner skin plate, and an appropriate number and an appropriate interval may be provided between the skin plate and the inner skin plate. You may set it up. In addition to the segments, a fume pipe and cast-in-place concrete can be considered as the lining portion.

In the tail seal structure of the present invention, when the thickness of the gap between the outer surface of the segment of the shield tail portion and the inner surface of the skin plate, that is, the tail clearance changes, a segment having a normal thickness such as an RC segment is used. When forming a shield tunnel using
There is a case where a thin segment (for example, a ductile segment or a steel segment, which is thin when compared with a segment having a normal thickness) is changed from a certain point. At this time, since the tail clearance is expanded, the tail seal structure of the present invention is provided in the shield tail portion,
Prevent groundwater, sediment, backfill injection material and seismic isolation material from entering the shield machine.

Contrary to the above, when the tail clearance is changed, the tail seal structure of the present invention is provided in the shield tail portion, and when the shield tunnel is formed by the thin segment, the tail clearance is usually changed from a certain point. It may be replaced with a thickness segment. At this time, since the tail clearance is reduced, the tail seal structure of the present invention is removed from the shield tail portion. The tail seal structure of the present invention can be removed by cutting the welded and fixed portion of the fixing means or removing the screw at the screwed portion.

In the tail seal structure of the present invention, the outer diameter of the inner skin plate is a segment having a normal thickness,
For example, the outer diameter may be the same as the outer diameter of the RC segment. By making the outer diameter the same as described above, when the inner skin plate is assembled into a ring shape, the inner skin plate is normally used without adjusting the height of the segment assembly guide. be able to.

In the tail seal structure of the present invention, a spacer may be provided between the skin plate and the inner skin plate in order to maintain a constant distance therebetween. By providing the spacer, the central axis of the shield machine can be aligned with the central axis of the inner skin plate, so that the inner skin plate can be prevented from being offset. This spacer may be a bolt having a screw hole on the inner skin plate and screwed to reach the skin plate from this hole. The height of the inner skin plate can be freely adjusted by using the bolt. be able to. Further, a nut may be provided on the inner skin plate so as to communicate with the hole having the screw thread, and by providing the nut, the bolt can be screwed without forming the screw thread in the hole having the screw thread. Can be put and fixed. Further, a spacer stopper having a groove for engaging the tip of the bolt may be provided at a portion where the bolt and the skin plate come into contact with each other.

In the tail seal structure of the present invention, the first tail seal and the second tail seal can use a tail seal composed of a wire brush type seal material and a seal material mounting metal fitting. Mold tail seal material is provided at appropriate places, for example, about 1 to 4 places, continuously along the entire inner circumference of the skin plate and inner skin plate, and special high viscosity grease is injected between the wire brush type tail seal materials. You may.
By injecting the high-viscosity grease in this way, it is possible to further enhance the effect of preventing the inflow of groundwater, earth and sand, backfill injection material and seismic isolation material into the shield machine. Also, the second tail seal is attached so as to contact the outer surface of the thin segment. At this time, if the mounting height adjustment base is provided on the inner skin plate over the entire inner circumference and the sealing material mounting bracket is fixed on the mounting height adjustment base, even if the outer diameter difference between the normal segment and the thin segment is large. It is possible to use the second tail seal as it is without having to lengthen the sealing material itself.

Another aspect of the present invention is a shield construction method for forming a seismic isolation layer between an outer surface of a lining portion and a ground surface near a boundary between a hard stratum and a soft stratum. At the formation start point, the inner skin plate equipped with water blocking means was assembled into a ring shape with a smaller diameter than the skin plate in the shield machine, and the outer diameter was smaller than the lining part of the normal thickness used before the start point. Assembling a thin lining part with approximately the same inner diameter, digging the shield machine by applying a reaction force to both or one of the inner skin plate ring and thin lining part assembled in the above process, and then digging the entire inner surface of the skin plate. The inner skin plate ring is fixed in contact with the inside of a tail seal provided over the circumference, and the thin lining portion is covered with a normal thickness cover already formed.
It is connected to the work part, and a new thin type is added in front of the thin lining part.
By rolling up the lining part , excavating the shield machine, and repeating the step of backfilling the seismic isolation material a predetermined number of times,
A shield that forms a seismic isolation layer, at the end point of the seismic isolation layer formation, releases the inner skin plate ring and then forms a lining part with the same normal thickness as before the seismic isolation layer formation start point. It is in the construction method.

In the shield construction method for forming the seismic isolation layer of the present invention, the water blocking means is composed of a wire brush type seal material and a seal material mounting metal fitting as in the second tail seal used in the tail seal structure. The same tail seal can be used, the number of attachments, the attachment points, and the attachment method can be the same, whereby a sufficient water blocking effect in the tail clearance can be obtained.

In the shield construction method for forming the seismic isolation layer of the present invention, an elastic material such as urethane resin or bentonite can be used as the seismic isolation material. A seismic isolation layer can be formed between the surface and the surface. At this time, the seismic isolation layer has a diameter of 5
For m-class tunnels, a thickness of 30 cm or more is desirable. By forming such a seismic isolation layer, even if a large earthquake of the Kanto earthquake level occurs and a ground displacement amount of 25 cm to 30 cm occurs, the seismic isolation layer with a thickness greater than the ground displacement amount is generated. Since it is elastically deformed and absorbed, its ground displacement is hardly transmitted to the shield tunnel, and therefore the shield tunnel can obtain earthquake resistance.

In the shield construction method for forming the seismic isolation layer of the present invention, the thin segment means that, when compared with a segment having a normal thickness, the inner diameter is the same, the thickness is smaller than the ground displacement amount, and the strength can withstand earth pressure. I have. The material of the thin segment and the segment of normal thickness are not particularly limited.

In the shield construction method for forming the seismic isolation layer of the present invention, the steps of assembling the thin segment ring, excavating the shield machine, and injecting the seismic isolation material are repeated a predetermined number of times, for example, a hard layer and a soft layer. 40 before and after the border
It is to form a seismic isolation layer continuously within a range of up to 50 m, and a necessary seismic isolation layer can be appropriately formed by repeating this process several times.

[0022]

According to the tail seal structure of the present invention, the tail seal is provided in double by providing the skin plate provided with another tail seal inside the tail seal provided inside the skin plate of the shield tail portion. By doing so, even when the tail clearance changes, groundwater, earth and sand, backfill material and seismic isolation material are prevented from flowing into the shield machine.

Further, in the shield construction method of the present invention, the tail void is thickened near the boundary between the hard formation and the soft formation by using thin segments. Even in the formation of seismic isolation layer,
It is possible to prevent groundwater, earth and sand, and backfill injection material and seismic isolation material from flowing into the shield machine.

[0024]

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a schematic sectional view of a shield machine for excavating while forming a base isolation layer using the tail seal structure of the present invention. 2 (a) is an enlarged sectional view of the tail seal structure of the present invention, FIG. 2 (b) is an AA sectional view of FIG.
FIG. 2C is a sectional view showing a fixing method of the tail seal material different from that shown in FIG. 2A, and FIG. 2D is a sectional view showing a fixing means of the inner skin plate different from that shown in FIG. 2A.
The tail seal structure of the present invention includes a first tail seal 2 provided on the entire inner surface of the skin plate 1 of the shield tail portion, and an inner skin provided on the inner circumference of the first tail seal 2 in contact with the first tail seal 2. The plate 3, a fixing plate 5 as a fixing means for fixing the inner skin plate 3, and a second tail seal 4 provided all around the inner surface of the inner skin plate 3.
And are provided as main parts.

Here, the fixed plate 5 is provided between the end 3a of the inner skin plate and the inner surface of the skin plate 1.
It is fixed by welding at 6 points (see FIG. 2 (b)). In addition,
The fixing plate is a skin plate 1 as shown in FIG.
It can also be fixed to the inner surface of the sheet and the end of the inner skin plate 3 by bolts 5 ".

Further, the first tail seal 2 and the second tail seal 4 (refer to FIG. 2A below) are the wire brush type tail seal materials 2a and 4a and the seal material attachment fittings 2b and 4b, respectively. The wire brush type tail seals 2 and 4 are continuously provided on the entire inner circumferences of the skin plate 1 and the inner skin plate 3, respectively.
Inject special high-viscosity grease between 4a and the seal.
Furthermore, the second tail seal 4a is the thin segment 1
It mounted so as to be in contact with the 0 outer surface. Note that normal segments
When the difference in outer diameter between the thin segment 10 and the thin segment 10 is large, as shown in FIG. 2 (c), the mounting height adjustment base 4c continuous to the entire inner circumference of the inner skin plate is welded, and the sealing material is provided thereon. By welding the mounting member 4b, it is not necessary to lengthen the sealing material 4a itself of the second tail seal 4,
It can be used as it is.

Except for the above-mentioned main parts, a spacer 7a is provided between the skin plate 1 and the inner skin plate 3 for maintaining a constant space therebetween. The spacer 7a is formed by all screws (bolts without bolt heads), and a hole 7d formed in the inner skin plate 3 and a nut welded on the inner skin plate 3 so as to communicate with the hole 7d. It is screwed so as to reach the spacer stopper 7b which is welded on the skin plate 1 through 7c. In addition, at a portion of the spacer stopper 7b with which the spacer 7a abuts, a hole for locking the tip of the spacer 7a is provided.

Next, referring to FIGS. 1 and 3 (a) to 3 (c), the shield machine 30 having the tail seal structure of the present invention is used to form the outer surface of the thin segment 10 and the ground near the boundary between the hard ground and the soft ground. A shield construction method for forming the seismic isolation layer 20 between the mountain 12 will be described.

At the starting point of the seismic isolation layer formation, first of all, the segment assembly space within the shield machine 30, that is, the inner skin plate having the same outer diameter as the outer diameter of the segment having the normal thickness, for example, the RC segment 11 in the shield tail portion 34. 3 is assembled in a ring shape, and the tail seal material 4a which is continuous to the entire inner circumference is attached to the inner skin plate 3 at two locations by the seal material attachment fittings 4b.
At this time, a normal segment guide (not shown) used when assembling the RC segment 11 is placed at several places below the skin plate 1, and the inner skin plate 3 is assembled on this. Further, the length of the tail seal material 4a is such that it can come into contact with the surface of a thin segment guide described later to obtain sufficient water blocking performance.

Next, thin segment guides (not shown) are attached to the inner skin plate 3 at several places under the inner surface thereof, and thin segments, for example, steel segments 10 are assembled inside the inner skin plate 3. At this time, the thin segment guide prevents the tail seal material 4a from being excessively deformed by the weight of the steel segment when the steel segment 10 is assembled in a ring shape.

After the inner skin plate 3 and the steel segment 10 are assembled into a ring shape, the steel segment 1
0 is fixed to the RC segment 11 with a bolt (not shown) or the like. Then, the jack 31 of the shield machine 30 is extended and a thrust is applied to both the inner skin plate 3 and the steel segment 10, that is, a reaction force is applied to the inner skin plate 3 and the steel segment 10, and the jack 3
1 is extended and the thrust is applied to the bulkhead 32, the cutter head 33 excavates the face 13, and the shield machine 3
0 is moved to the end of the shield tail portion 34.

Next, several portions of the ring-shaped inner skin plate 3 are fixed to the inner surface of the skin plate 1 by the fixing plate 5. At this time, the bolt hole of the RC segment 11 (not shown), so as to communicate with the connecting bolt hole of the thin segment ends. Also, inner skin plate 3
In order to keep the distance between the skin plate 1 and the skin plate 1 constant, spacers 7a are provided at several places between them. The spacer 7a is screwed into the bolt hole on the surface of the inner skin plate 3 through the spacer insertion hole 14 of the steel segment 10 until it reaches the skin plate 1. The spacer insertion hole 14 is also used as an injection hole when the seismic isolation material is injected, and the insertion hole 14 is covered.

After fixing the ring-shaped inner skin plate 3 to the skin plate 1 in this manner, the steel segment 10 is assembled into a ring shape at the shield tail portion 34, the shield machine 30 is dug, and seismic isolation is sequentially performed. The step of backfilling the material 21 from the injection hole 14 of the steel segment is repeated a predetermined number of times, and the seismic isolation layer 2 having a total length of about 40 to 50 m.
Form 0.

After the seismic isolation layer 20 is formed, the fixing plate 5
Also, the spacer 7a is removed, and the fixation between the inner skin plate 3 and the skin plate 1 is released. Then
After contracting the jack 31 of the shield machine 30, the RC segment 11 of normal thickness is provided at the shield tail 34.
Is assembled in a ring shape, a reaction force is taken, the jack 31 is extended, and the thrust is applied to the bulk head 32, while the cutter head 33 excavates the face 13 to propel the shield machine 30. That is, the jack 31 is extended, and thrust is applied to the RC segment 11 to move it to the end of the shield tail portion 34, that is, until it comes into contact with the steel segment 10 and the inner skin plate 3.

[0036]

According to the tail seal structure of the present invention, when the tail void is thickened by using the thin segment and the seismic isolation layer is formed, even if the tail clearance of the shield machine is expanded or contracted, this tail clearance is reduced. Can be reliably sealed to prevent groundwater, soil, and backfill pouring material from being pressed into the shield machine.

In the shield method of the present invention, in the vicinity of the boundary between the hard stratum and the soft stratum, when the tail void is thickened by using the thin segment to form the seismic isolation layer, groundwater, earth and sand, backfilling injection material and It is possible to prevent the seismic isolation material from flowing into the shield machine.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of a shield machine that excavates while forming a seismic isolation layer using the tail seal structure of the present invention.

2A is an enlarged cross-sectional view of a tail seal structure of the present invention, FIG. 2B is a cross-sectional view taken along the line AA of FIG. 1, and FIG. 2C is a method of fixing a tail seal material different from FIG. Sectional view, (d)
FIG. 7A is a cross-sectional view showing a fixing means for an inner skin plate different from that shown in FIG.

3 (a) to 3 (c) are schematic explanatory views of a shield construction method for forming a seismic isolation layer according to the present invention.

4A is a schematic cross-sectional view of a conventional shield machine, and FIG. 4B is an enlarged schematic cross-sectional view of a tail seal portion of FIG.

[Explanation of symbols]

1 Skin Plate 2 First Tail Seal 3 Inner Skin Plate 4 Second Tail Seal 5 Fixing Plate (Fixing Means) 10 Thin Lining Part (Thin Segment) 11 Normal Thickness Lining Part (Regular Thickness Segment) 21 Seismic Isolation Material 30 Shield Machine 34 Shield Tail

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuo Onodera 1-27-3 Nishisakado, Sakado City, Saitama Prefecture (72) Inventor Masao Sayamoto 1251 Maeda, Hatogaya City, Saitama Prefecture Hatagaya Minami Mansion 406 (72) Inventor Numaguchi Eisuke 2-13-12 Aoki, Kawaguchi City, Saitama Prefecture Mates Kawaguchi, Aoki 402 (72) Inventor Hiroshi Manaka 1-3 C-502 (56), Kamazawa-minami, Kanazawa-ku, Yokohama, Kanagawa Pref. JP-A-4-203198 , A) JP 56-159500 (JP, A) JP 5-263590 (JP, A) Actually open 2-66895 (JP, U) Actual 53-42439 (JP, U) (58) Fields surveyed (Int.Cl. ⁷ , DB name) E21D 11/00 E21D 11/14

Claims (2)

(57) [Claims] 1. To prevent groundwater, earth and sand, or backfill material from flowing into the shield machine from the gap when the gap thickness between the outer surface of the lining portion of the shield tail portion and the inner surface of the skin plate changes. Water-stopping structure of, the first tail seal provided on the entire circumference of the inner surface of the skin part of the tail portion, and the inner skin plate provided on the entire inner circumference in contact with the first tail seal, A tail seal structure comprising: fixing means for fixing the inner skin plate; and a second tail seal provided on the entire inner surface of the inner skin plate and in contact with the lining portion. 2. A shield construction method for forming a seismic isolation layer between an outer surface of a lining portion and a ground surface in the vicinity of a boundary between a hard stratum and a soft stratum, which is a shield machine at a seismic isolation layer formation start point. Inside, the inner skin plate equipped with water stopping means is assembled into a ring shape with a smaller diameter than the skin plate, and the outer diameter is smaller than the lining part of the normal thickness used before the starting point, and the inner diameter is almost the same. Assembling the lining part, excavating the shield machine by applying reaction force to both or one of the inner skin plate ring and the thin lining part assembled in the above process, and then tail seal provided over the entire inner surface of the skin plate. with the inside in contact to fix the inner skin plate ring, the normally connected to lining of the thickness that has already been formed a thin lining portion, further, before the thin lining portion Make up the Tana thin lining unit, and excavation the shield machine, by repeating a predetermined number of times the step of backfilling the seismic isolation material, to form a seismic isolation layer, with the seismic isolation layer formation end point, A shield construction method in which the inner skin plate ring is unfixed, and then a lining portion having the same normal thickness as before the seismic isolation layer formation start point is formed.