JP5155680B2 - Backfill injection method, tunnel construction system and tunnel construction method - Google Patents

Description

  The present invention relates to a backfill injection method, a tunnel construction system, and a tunnel construction method.

  A gap called a tail void is formed between the wall of the excavated excavation hole and the segment behind the shield excavator during excavation. Since this tail void causes loosening and settlement of the ground, it is necessary to fill it as soon as possible after passing through the shield machine. The work of filling the tail void is generally called backfilling. The material injected into the tail void is generally called an injection material or a backfill injection material. The injection material is required to have performance such as no material separation and a small volume change after injection (see Non-Patent Document 1, pages 71 to 73).

Conventionally, as an injecting material, a material in which a solidifying material such as cement, a mineral-based auxiliary material, and a stabilizing material (retarding material) such as sodium gluconate is used is used. Recently, a mixed-type injection material is also used in which a liquid A containing a solidifying material and a liquid B containing a plastic strength adjusting material such as sodium silicate are mixed.
Shield Construction Method Introduction Editorial Committee, “Shield Construction Method Introduction”, 3rd printing, Geotechnical Society of Japan, June 10, 1996, p. 71-73

  By the way, since the injection material filling the tail void is required to have the above-mentioned performance, when preparing this, the solidifying material, the mineral-based auxiliary material, the stabilizing material and the plastic strength adjusting material are all commercially available. It is common to use. However, if all these materials are covered by commercial products, there is a problem that the cost increases.

  On the other hand, when excavation is performed by the earth pressure type shield excavator, excavated soil is discharged from the excavator, and it is also costly to dispose it as construction sludge. Therefore, it is desired to reduce the amount of excavated soil to be disposed as construction sludge.

  The present invention has been made in view of such circumstances, and can reduce the raw material cost of the backfilling injection material and reduce the amount of excavated soil to be disposed as construction sludge, and the tunnel construction It is an object to provide a system and a tunnel construction method.

  The backfill injection method according to the present invention is discharged from the earth pressure shield machine into the space between the wall surface of the excavation hole excavated by the earth pressure shield machine and the outer surface of the segment installed in the excavation hole. It is characterized by injecting an injection material containing viscous soil contained in excavated soil.

  According to the backfill injection method according to the present invention, by mixing the clay contained in the excavated soil from the earth pressure type shield excavator into the injecting material, it is compared with the case of preparing the injecting material using all commercially available materials. In addition, the raw material cost of the injection material can be reduced. Further, by using the viscous soil as a part of the raw material of the injection material, it is possible to reduce an amount of construction sludge that is at least equivalent to the blending amount of the viscous soil.

  The backfilling injection method according to the present invention may include a classification step of separating and collecting massive consolidated viscous soil from excavated soil. When the clay is included in the excavated soil as a massive solid clay, the clay can be easily recovered from the excavated soil by classifying the excavated soil with a sieve or the like.

  When consolidated cohesive soil is recovered from excavated soil by classification, the backfill injection method according to the present invention includes a pulverizing step of pulverizing the consolidated viscous soil, and a mixing step of mixing the pulverized viscous soil and cement It is preferable to further comprise. When cement is mixed with pulverized viscous soil and mixed, it becomes easy to obtain granular viscous soil due to the granulation effect of cement. By using granular viscous soil for the preparation of the injection material, the quality of the injection material can be made uniform.

  The tunnel construction system according to the present invention excavates in the ground to form excavation holes, and earth pressure type shield excavators in which segments are arranged in the excavation holes, and viscosity from excavated soil discharged from earth pressure type shield excavators Classifying means for separating and collecting the soil, and backfilling injection means for injecting an injection material mixed with the collected viscous soil into the space between the wall surface of the excavation hole and the outer surface of the segment installed in the excavation hole It is characterized by providing.

  According to the tunnel construction system according to the present invention, the backfill injection method according to the present invention can be performed simultaneously with excavation of the shield tunnel. This can reduce the raw material costs of backfilling material and reduce the amount of excavated soil to be disposed of as construction sludge.

  The classification means in the tunnel construction system according to the present invention may be a sieve that separates and collects massive consolidated viscous soil from excavated soil. When viscous soil is contained in the excavated soil as a massive consolidated viscous soil, the viscous soil can be easily recovered from the excavated soil by adopting a sieve as a classification means.

  When consolidated clay is obtained from excavated soil by classification with a sieve, the tunnel construction system according to the present invention includes a pulverizing unit for pulverizing the consolidated viscous soil, and a mixing unit for mixing the pulverized viscous soil and cement. It is preferable to further comprise. When cement is mixed with pulverized viscous soil and mixed, it becomes easy to obtain granular viscous soil due to the granulation effect of cement. By using granular viscous soil for the preparation of the injection material, the quality of the injection material can be made uniform.

  In addition, the tunnel construction system according to the present invention transports a part of the remaining excavated soil from which at least a part of the viscous soil is removed by the classifying means and the content of the viscous soil is reduced into the existing segment. Preferably further means are provided. By transferring a part of the remaining excavated soil into the existing segment, the excavated soil can be effectively used for invert construction in which a substantially flat bottom surface or the like is laid in the segment. As a result, the amount of excavated soil to be disposed as construction sludge can be further reduced.

  The tunnel construction method according to the present invention includes an excavation process in which an earth pressure type shield excavator excavates to form an excavation hole, and a segment is arranged in the excavation hole, and the viscosity from excavated soil discharged from the earth pressure type shield excavator A classification process for separating and collecting the soil, and a backfilling injection process for injecting an injection material mixed with the separated and collected viscous soil into the space between the wall surface of the excavation hole and the outer surface of the segment disposed in the excavation hole; , A transporting process for transporting a part of the remaining excavated soil in which at least a part of the viscous soil is removed by the treatment in the classification process and the content of the viscous soil is reduced into the existing segment, and the remaining excavated soil And a bottom surface laying step of forming a substantially flat bottom surface in an existing segment.

  According to the tunnel construction method according to the present invention, the backfill injection method according to the present invention can be performed simultaneously with the excavation of the shield tunnel, and a substantially flat bottom surface can be formed in the existing segment. In the tunnel construction method according to the present invention, the construction sludge is used for invert construction in which a substantially flat bottom surface is laid in an existing segment, and a portion of the remaining excavated soil after the viscous soil is separated and recovered is used. As a result, the amount of excavated soil to be disposed of can be further reduced. In addition, the remaining excavated soil having a viscous soil content is suitable as a soil material for laying the bottom surface in the segment in that it is easier to compact than the excavated soil before separating and collecting the viscous soil.

  According to the present invention, the raw material cost of backfilling injection material can be reduced, and the amount of excavated soil to be disposed as construction sludge can be reduced.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.

(Tunnel construction system)
FIG. 1 is a side sectional view showing an earth pressure type shield machine 15 provided in the tunnel construction system 100 according to the present embodiment. FIG. 2 is an enlarged side sectional view showing the rear end portion of the shield machine 15.

  As shown in FIG. 1, the shield machine 15 includes an outer cylinder portion 1. A cutter head 2 is provided in front of the front end opening of the outer cylinder portion 1. Further, a partition plate 3 is provided at a position slightly rearward from the front end portion of the outer cylinder portion 1.

  The cutter head 2 has a number of cutter bits 2a on the front surface thereof. The cutter head 2 is attached to the partition plate 3 via a rotating shaft 4 a that is rotated by a motor 4. The cutter head 2 rotates as the rotating shaft 4a rotates. The cutter bit 2a cuts a natural ground by the rotation of the cutter head 2, and excavation is performed.

  The partition plate 3 is disposed so as to close the front opening of the outer cylinder portion 1, and forms a cutter chamber 5 together with the distal end portion of the outer cylinder portion 1 and the cutter head 2. In the earth pressure type shield machine 15, the excavated soil generated in the excavation is filled in the cutter chamber 5, and the pressure in the cutter chamber 5 is set so as to be substantially equal to the earth pressure of the ground and the groundwater. Adjust. This prevents sediment and groundwater from entering the outer tube portion 1.

  A tip of an additive injection tube 3a is connected to the partition plate 3, and various additives are added to the excavated soil in the cutter chamber 5 through the additive injection tube 3a. A base end 8 a of the screw conveyor 8 is connected to the lower position of the partition plate 3. The screw conveyor 8 takes in the excavated soil from the base end 8 a and discharges the excavated soil in the cutter chamber 5. The excavated soil taken in from the base end 8a moves upward in the casing 8b, and is discharged onto the belt conveyor 9 from the front end 8c.

  The excavated soil discharged from the tip 8c of the screw conveyor 8 is conveyed to the subsequent carriage by the belt conveyor 9 (see FIG. 3). As will be described later, a backfill injection material containing the viscous soil separated and recovered from the excavated soil is prepared through the processing in the subsequent carriage, and this is injected into the tail void.

  A shield jack 12 is provided at the rear portion of the outer tube portion 1. The shield jack 12 includes a shield jack rod 12a and a shield jack cylinder 12b. The tip of the shield jack rod 12a presses the assembled segment S. By pressing the segment S with the shield jack rod 12a, a reaction force is applied to the segment S to advance the shield machine 15.

  A tail seal 20 is provided at the rear end portion of the outer cylinder portion 1. The tail seal 20 stops water between the segment S and the shield machine 15 at the rear end portion of the shield machine 15. As shown in FIG. 2, the tail seal 20 includes a first stage tail seal 20a, a second stage tail seal 20b, and a third stage tail seal 20c. Among these, the third-stage tail seal 20c is provided at the innermost rearmost end portion of the outer cylinder portion 1, and the second-stage tail seal 20b is provided in front of the outer cylinder portion 1 inside the outer cylinder portion 1. A first-stage tail seal 20a is further provided on the inner side of the front side. The segment S assembled rearward and the inner side of the outer cylinder part 1 are closed by the tail seal 20 to prevent intrusion of earth and sand or groundwater into the outer cylinder part 1. In the present embodiment, the tail seal 20 has three stages. However, the number of stages of the tail seal is not three, but may be one stage, two stages, or four stages or more.

  The segment S has a through hole S1 penetrating from the inner surface toward the outer surface, and as shown in FIG. 2, the backfilling injection material U is passed through the through hole S1 to the outer surface of the segment S and the ground (excavation). It can be injected into the space between the wall of the hole).

  Next, classification means, crushing means, mixing means, and backfill injection means included in the tunnel construction system 100 according to the present embodiment will be described with reference to FIGS.

  FIG. 3 is a schematic cross-sectional view showing a preferred embodiment of the tunnel construction system 100 according to the present embodiment, that is, the following carts C1 to C5 equipped with the classification means, the pulverization means, etc. are shielded in the tunnel 30. It is a figure which shows the state arrange | positioned at the back of the machine. As shown in FIG. 3, the tunnel 30 constituted by the assembled segments S is inverted to form a substantially flat bottom surface 30 a. The first subsequent carriage C1 is connected to the shield machine 15 by a connecting member (not shown). Thereby, with the excavation of the shield machine 15, the first to fifth subsequent carriages move forward on the rail provided on the bottom surface 30a.

  The first succeeding carriage C1 includes a classifier for separating and collecting viscous soil from a part of excavated soil conveyed by the belt conveyor 9, a stirrer for preparing a soil material for invert construction, and the like. FIG. 4 shows an apparatus suitable for being mounted on the first succeeding carriage C1. The classifier 32 shown in FIG. 4 has a simple sieve (classifying means) 32a called a grizzly bar. When the clay is included in the excavated soil as the massive consolidated viscous soil M1, the consolidated viscous soil M1 can be easily separated and recovered from the excavated soil by using the simple sieve 32a. The consolidated viscous soil M1 separated from the excavated soil is conveyed to the second succeeding carriage C2 via the chute 32b and a belt conveyor (not shown).

  On the other hand, the excavated soil from which the consolidated viscous soil M1 is removed by the simple sieve 32a and the content of the viscous soil is reduced becomes the soil material M2 for invert construction through the following treatment. That is, the excavated soil falling downward on the simple sieve 32a is subjected to a modification process by the stirrer 34 after the cement supplied from the cement feeder 33 is added to become a soil material M2. This soil material M2 is conveyed to the base end side of the belt conveyor (conveying means) 36 through the screw conveyor 35. The belt conveyor 36 extends in the direction of the tip of the tunnel 30 and can transport the soil material M2 to a region where the invert work is not performed or a region during the invert work (see FIG. 3).

  The second subsequent carriage C2 includes a pulverizer for pulverizing the consolidated clay soil M1 from the first subsequent carriage C1. FIG. 5 shows an apparatus suitable for mounting on the second succeeding carriage C2. The crusher 42 shown in FIG. 5 mixes the rotary hopper 42a for mixing the cement supplied from the cement feeder 43 with the consolidated viscous soil M1, the cement and the viscous soil, and pulverizes the consolidated viscous soil M1. The crushing shaft 42b and the rotary hammer 42c are configured. In addition, the said apparatus mounted in the 2nd succeeding trolley | bogie C2 plays a role as a mixing means of a viscous soil and cement while serving as a crushing means of the consolidated viscous soil M1.

  The viscous soil material M3 containing granular viscous soil can be obtained by passing through the process in the crusher 42 with which 2nd succeeding trolley | bogie C2 is equipped. This viscous earth material M3 is conveyed to the third succeeding carriage C3 via the belt conveyor 45.

  As shown in FIG. 6, the third subsequent carriage C3 includes a hopper 52 that stores the clay soil material M3 conveyed from the second subsequent carriage C2 through the belt conveyor 45. By storing a certain amount of the clay soil material M3, for example, even if the shield machine 15 enters a layer with a low content of clay soil and the amount of clay soil separated and recovered from the drilled soil decreases, There is an advantage that the backfilling injection material can be stably prepared for a certain period.

  The fourth succeeding carriage C4 includes a mixer 62 that mixes the viscous earth material M3 conveyed from the third succeeding carriage C3 with water, and a storage tank 64 that stores the viscous earth-containing liquid obtained through the processing in the mixer 62. With.

  The fifth succeeding carriage C5 includes an injection material preparation tank 72 for preparing the backfilling injection material U. The injection material preparation tank 72 stores the viscous soil-containing liquid transferred from the storage tank 64 of the fourth subsequent carriage C4 through the pipe L65. The A liquid of the backfilling injection material U is prepared by blending the solidifying material, the auxiliary material, and the stabilizing material with the viscous soil-containing liquid in the injection material preparation tank 72. The backfilling injection material U is finally obtained by adding the B liquid containing the plastic strength adjusting material to the A liquid immediately before the backfilling injection work.

  The fifth succeeding carriage C5 further includes a backfill injection facility (backfill injection means) 75 for pumping the backfill injection material U. The backfill injection equipment 75 includes a transfer pump 76, a hose 77 connected to the transfer pump 76, and a nozzle 78 provided at the tip of the hose 77. The hose 77 extends to the position of the segment S immediately after assembly (see FIG. 3). The nozzle 78 can be inserted into a through-hole S1 provided in the segment S. The back pumping material U is injected into the tail void by starting the transfer pump 76 with the nozzle 78 inserted into the through hole S1 (see FIG. 2).

(Backfill injection method and tunnel construction system method)
According to the tunnel construction system 100 according to the present embodiment, the backfill injection method according to the present invention can be implemented immediately after the formation of the excavation hole by the shield machine 15. The backfilling injection method implemented by the tunnel construction system 100 is a method in which the backfilling injection material U in which the clay soil separated and recovered from the excavated soil is mixed in the space between the outer surface of the segment S and the ground is penetrated through the segment S. Inject through S1. The method of injecting the backfilling injection material from the through hole S1 of the segment S is generally called immediate injection.

  In this embodiment, the backfill injection method first separates and collects the consolidated viscous soil M1 from the excavated soil using the simple sieve 32a of the classifier 32 (classification step). Next, the consolidated viscous soil M1 obtained through this classification step is pulverized by the crusher 42, and the cement supplied from the cement feeder 43 and the pulverized viscous soil are mixed (pulverization step and mixing step).

  The cement supplied from the cement feeder 43 is preferably 2.5 to 3.0 parts by mass and preferably 2.6 to 2.8 parts by mass with respect to 100 parts by mass of consolidated clay soil M1. preferable. By blending an amount of cement within the above range, the granulation effect by the cement can be expected, and it becomes easy to obtain granular clay soil. In addition, there exists an advantage that the quality of a backfilling injection material can be equalize | homogenized by preparing granular viscous soil beforehand and using this for preparation of a backfilling injection material.

  Using the clay soil material M3 obtained through the above steps, the backfilling injection material U is finally prepared in the fifth succeeding carriage C5 (injection material preparation step). After inserting the nozzle 78 provided in the backfill injection equipment 75 into the through hole S1 of the segment S, the transfer pump 76 is activated to inject the backfill injection material U into the tail void (injection step).

  In the tunnel construction method according to the present embodiment, in addition to the steps included in the backfill injection method described above, an excavation step in which a drilling hole is formed by the shield excavator 15, and a soil material M2 for invert construction is provided on the belt conveyor 36. It further includes a transporting process for transporting into the segment S, and a bottom laying process for laying the soil material M2 and forming a substantially flat bottom surface 30a in the existing segment S using a rolling roller or the like ( (See FIG. 3).

  According to the tunnel construction system 100 according to the present embodiment, and the backfill injection method and the tunnel construction method using the tunnel construction system 100, the following effects can be obtained. That is, since the consolidated viscous soil M1 contained in the excavated soil is used as a part of the raw material of the backfilling injection material U to be injected into the tail void, compared with the case of preparing the same volume of the injection material with a commercially available material, The raw material cost of the injection material can be reduced. In addition, it is possible to reduce the amount of construction sludge equivalent to the blending amount of the viscous soil.

  In addition, according to the present embodiment, the soil material M2 having a reduced content of the viscous soil can be conveyed via the belt conveyor 36 to a region where the invert work is not performed or a region during the invert work. By using the soil material M2 made of excavated soil as the raw material for the invert construction for laying the bottom surface 30a, the amount of excavated soil to be disposed as construction sludge can be further reduced. The soil material M2 is suitable as a soil material for laying the bottom surface 30a because the clay soil is reduced as compared with the excavated soil as it is discharged from the shield machine 15 because the clay soil is reduced. It is.

  Furthermore, according to the present embodiment, a series of steps of separating and collecting the viscous soil from the excavated soil and preparing the backfilling injection material U using the same is performed in the tunnel 30 without carrying the excavated soil to the ground. This can be done with the following truck. As a result, since the cycle from the classification process and the injection material preparation process to the injection process can be sufficiently shortened, the deterioration of the performance of the backfilling injection material U is sufficiently suppressed, and the backfilling injection material U having the desired performance is tail-voided. Can be injected into.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment. For example, in the above embodiment, as a backfill injection method, a method of injecting the backfill injection material U into the tail void from the through hole S1 of the segment S (so-called immediate injection) has been exemplified. A method (so-called simultaneous injection) in which the filling material U is injected into the tail void from the rear end portion of the outer cylindrical portion 1 may be employed.

  Moreover, in the said embodiment, although viscous soil was contained as excavated soil as consolidated viscous soil M1, the case where viscous soil was easily isolate | separated from excavated soil using the simple sieve 32a was illustrated, but it generate | occur | produces. In the case where the viscous soil in the excavated soil is not consolidated into a lump, the viscous soil may be separated from the excavated soil using a conventionally known classification method.

  Furthermore, in the above embodiment, the tunnel construction system 100 provided with five subsequent carriages for processing excavated soil has been exemplified, but the number of subsequent carriages may be changed as appropriate according to the inner diameter of the tunnel and the amount of excavated soil. May be.

<Evaluation test of backfill injection material>
An injection material prepared using viscous soil separated and recovered from excavated soil and an injection material prepared without using clay soil were prepared, and an evaluation test of each injection material was performed.

(Experimental example 1)
Backfilling injections with the formulations shown in Table 1 were prepared. The viscous soil shown in Table 1 is obtained by separating and recovering consolidated viscous soil from excavated soil using an apparatus having the same configuration as the classifier 32 shown in FIG. 4, and this is the same as the crusher 42 shown in FIG. 5. It processed using the apparatus of the structure. Moreover, the value shown in Table 1 means the blending amount of each raw material per 1 m ^{3 of the} backfilling injection material prepared in this experimental example.

(Comparative Example 1)
Backfilling injections with the formulations shown in Table 2 were prepared. In addition, the value shown in Table 2 means the blending amount of each raw material per 1 m ^{3 of the} backfilling injection material prepared in this comparative example.

<Evaluation test>
(1) P funnel flow time P funnel flow time is measured according to JSCE-F521-1994 “Testing method for fluidity of injected mortar of prepacked concrete (P funnel method)” with A liquid as the sample to be measured. It is a measured value.
(2) Density Density is obtained by using the backfilling injection material immediately after mixing the liquid A and the liquid B as a sample to be measured.
(3) Bleeding rate The bleeding rate is a value measured in accordance with Japan Society of Civil Engineers standard JSCE-F522 "Testing method for bleeding rate and expansion rate of pre-packed concrete mortar (polyethylene bag method)".
(4) Gel time Gel time is about 1L of liquid A and a predetermined amount of liquid B are quickly mixed using a hand mixer in a 1.5L beaker until it no longer flows out even if the beaker is tilted. Means time.
(5) Uniaxial compressive strength The uniaxial compressive strength is JIS A 1216 “Soil uniaxial compressive testing method” using the backfilling injection material 1 hour and 28 days after mixing liquid A and liquid B. It is a value measured according to.

As shown in Table 1, the backfilling injection material of Experimental Example 1 contains 495 kg of viscous soil per 1 m ³ . When the density of cohesive soil material M3 and 1.7t / ^{m 3,} viscosity soil backfill of Example 1 implanted material 1 m ³ per 0.29 m ³ it is blended. By using this pouring material in the backfill pouring work, it is possible to reduce the amount of construction sludge equivalent to the blending amount as compared with the case of using the pouring material of Comparative Example 1 that does not use viscous soil. In addition, as shown in Tables 1 and 2, the use of raw materials (solidification materials, auxiliary materials, stabilizers, plastic strength adjusting materials) generally purchased when preparing backfilling injection materials, as shown in Tables 1 and 2, by using viscous soil Any amount can be saved.

  Moreover, as shown in Table 3, it was shown that the backfilling injection material of Experimental Example 1 has sufficient performance even when compared with the evaluation result of the injection material of Comparative Example 1 that does not use viscous soil. .

It is side sectional drawing which shows the suitable form of the shield machine provided with the tunnel construction system which concerns on this invention. It is a sectional side view which expands and shows the rear-end part of the shield machine shown in FIG. It is a schematic cross section which shows the suitable form of the tunnel construction system which concerns on this invention. It is a perspective view which shows the suitable form of the apparatus mounted in the succeeding trolley | bogie C1. It is a perspective view which shows the suitable form of the apparatus mounted in the succeeding trolley | bogie C2. It is a schematic diagram which shows the suitable structure of succeeding carriage C3, C4, C5.

Explanation of symbols

DESCRIPTION OF SYMBOLS 15 ... Earth pressure type shield machine, 30a ... Bottom, 32a ... Simple sieve (classification means), 36 ... Belt conveyor (conveyance means), 42 ... Crusher (pulverization means, mixing means), 75 ... Backfill injection equipment (back 100 ... tunnel construction system, M1 ... consolidated clay, U ... backfill injection material, S ... segment.

Claims (5)

In the space between the wall surface of the excavation hole excavated by the earth pressure shield machine and the outer surface of the segment installed in the excavation hole, the viscous soil contained in the excavation earth discharged from the earth pressure shield machine A backfill injection method for injecting an injection material containing
Separated and recovered from the excavated soil is a massive consolidated viscous soil used for the preparation of backfill injection material, and excavated soil from which the consolidated viscous soil has been removed to reduce the content of the viscous soil. A classification process ;
Crushing step of crushing the consolidated clay,
A mixing step of mixing the crushed cohesive soil and cement;
Back-filling injection method, characterized in that it comprises a. An earth pressure type shield excavator that digs in the ground to form a digging hole and arranges a segment in the digging hole;
From the excavated soil discharged from the earth pressure shield machine, the massive consolidated viscous soil used for the preparation of backfilling injection material and the consolidated viscous soil are removed to reduce the content of the viscous soil. Classification means for separating and collecting the excavated soil ,
Pulverizing means for pulverizing the consolidated viscous soil;
A mixing means for preparing an injection material by mixing crushed clay and cement;
And the wall surface of the wellbore, the space between the outer surface of the segments installed in the drilling hole, the backfill injection means for injecting the injection material,
A tunnel construction system characterized by comprising: The tunnel construction system according to claim 2 , wherein the classification means is a sieve that separates and collects massive consolidated viscous soil from the excavated soil. The tunnel construction system according to claim 2 or 3 , further comprising transport means for transporting a part of the excavated soil with a reduced content of the viscous soil into an existing segment. An excavation step in which the earth pressure type shield excavator excavates to form a drilling hole, and a segment is disposed in the drilling hole;
From the excavated soil discharged from the earth pressure shield machine, the massive consolidated viscous soil used for the preparation of backfilling injection material and the consolidated viscous soil are removed to reduce the content of the viscous soil. A classification process for separating and recovering the excavated soil used for the preparation of the soil material for laying the bottom surface ,
Crushing step of crushing the consolidated clay,
Mixing step of mixing ground clay and cement to prepare backfilling injection material;
A backfill injection step of injecting the backfill injection material into the space between the wall surface of the excavation hole and the outer surface of the segment disposed in the excavation hole;
A transporting step for transporting excavated soil used for preparing the soil material for laying the bottom surface into an existing segment;
Laying excavated soil used to prepare the soil material for laying the bottom surface, and forming a substantially flat bottom surface in the existing segment;
A tunnel construction method comprising:

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