JPS61147000A - Prevention of back filling material in back filling materialsupply pipe - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Technical Field) The present invention prevents the backfilling material remaining in the backfilling material supply pipe for guiding the backfilling material into the gap between the lining segment and the ground from hardening. Concerning how to.

(Prior art) In the shield type tunnel excavation method, a lining segment is assembled at the rear of the shield body as the shield body moves forward, and there is a gap between the lining segment and the ground from inside the shield body. A backfilling material containing a cement component is injected through a backfilling material supply pipe extending outward from the shield.

When the backfilling material is continuously flowing through the backfilling supply pipe, the backfilling material does not harden within the supplying pipe. However, if the injection work of backfilling material is stopped due to new assembly of lining segments as the shield main body advances, change of workers, or suspension of excavation work, the backfilling material remaining in the supply pipe may harden, and especially when a hardening accelerator is added to the backing material, this tendency becomes strong in a short period of time. Such hardening of the backfilling material within the supply pipe makes it difficult to pour the backfilling material when restarting the injection.

Therefore, conventionally, the basic concept is to remove the backing material that is about to harden within the supply pipe from the supply pipe before hardening begins, so that the backing material does not remain in the supply pipe,
A piston is provided for pushing out the backfilling material remaining at the tip portion of the supply pipe extending rearward outside the shield body from the discharge port of the supply pipe, and after the backfilling injection operation is stopped, the piston is moved by a cylinder device. Attempts have been made to cause the backfilling material remaining at the tip of the supply pipe to be discharged from the outlet of the supply pipe, or to flush the backfilling material remaining in the supply pipe from the injection pipe with high-pressure water. Ta.

However, in the former method, it is necessary to provide a cylinder device for actuating the piston on the outer circumferential surface of the shield body, which complicates the configuration. The cylinder device may disturb the ground, and furthermore, it is impossible to clean other parts of the injection pipe other than the tip, and the backfill material may harden in other parts other than the tip. There are problems such as storage. Furthermore, in the latter method, treatment of the high-pressure water used for the cleaning poses a problem.

(Objective) Accordingly, an object of the present invention is to provide a method for preventing the backfilling material from hardening within the backfilling material supply pipe during suspension of injection of the backfilling material.

(Structure and Effects) The present invention focuses on the fact that whether or not a backfilling injection material containing a cement component starts to harden depends on the PH value of the backfilling injection material. In the part of the backfilling material supply pipe leading to the discharge port, there is a backfilling material containing a cement component and the PH of the backfilling material.
It is characterized by being filled with a mixture with carbon dioxide gas to reduce the value.

According to the present invention, the carbon dioxide gas mixed in the backfilling material reacts with the backfilling material to lower the pH value of the backfilling material to a value of, for example, 10 or less, at which the backfilling material will not harden. , hardening of the backfilling material within the supply pipe is prevented, and the backfilling material filled in the supply pipe as a mixture with carbon dioxide prevents groundwater from entering through the outlet.

The backfilling material filled in the supply pipe as a mixture with carbon dioxide gas is discharged from the supply pipe through the discharge port by the backfilling material being pumped through the supply pipe by restarting the backfilling material injection operation. Thereafter, the PH value is raised to a value that allows curing by mixing with new backing material that is not mixed with carbon dioxide gas. Therefore, the backfill material filled in the supply pipe as a mixture with carbon dioxide gas can be used as a suitable backfill material after restarting the backfill injection operation, and the carbon dioxide gas has an allowable amount of 5000 PPM. Since carbon dioxide is a gas with extremely low toxicity and is supplied for a very short time, no special post-treatment is required due to the use of carbon dioxide.

Furthermore, there is no need to provide a cylinder device or the like in the shield body in order to supply the mixture of carbon dioxide gas and backfilling material to the supply pipe, and the relatively simple structure allows backfilling to be carried out over almost the entire area within the supply pipe. Can prevent hardening of materials,
There is no disturbance of the ground like in the conventional method.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The features of the invention will become clearer from the following description of an illustrative embodiment, which shows an example of a device for carrying out the method yet to be invented.

The so-called Tonosho balanced shield type tunnel excavation device 10 shown in FIG. A partition wall 20 is provided, and a partition wall 20 is provided at the rear of the partition wall.
The shield body 12 is provided with a jack 24 that propels the shield body 12 by applying a reaction force to the jack 2.

The cutter head 14 is rotated by the operation of a drive device 30 connected to the rotation shaft 14a through a gear 26 provided on the rotation shaft 14a and a pinion 28 meshing with the gear. For example, by the operation of a screw conveyor 34 having a drive device 32 that is operated according to the digging of the excavation device 10,
atmospheric region 1 without causing a pressure drop in pressurized region 16.
They are sequentially discharged from the discharge port 36 of the screw conveyor, which is open at 8. Foam can be injected into the pressurized area 16 to provide water-stop properties and fluidity to the pickpocket in the pressurized area 16.

As the excavation device 10 advances, new segments 22 are additionally assembled one after another at intervals from the ground to cover the excavation wall surface 38, and in order to fill the gap between the lining segment 22 and the excavation wall surface 38. A backfilling material injection device 40 is provided in conjunction with the excavation device 10.

In the illustrated example, the injection device 40 includes a backfilling material supply pipe 42.
and a mixer 46 for mixing the backfilling material and the hardening accelerator which are pumped through the hardening accelerator feed pipe 44, and the mixer adds the hardening accelerator and transfers the mixed backfilling material to the segment 22. and a backfill material supply pipe 48 extending outwardly from the mixer 46 through the shield body and extending rearwardly along the shield body to guide the backfill material into the gap between the The filling material supply pipe returns to a discharge port 50 which opens into the gap behind the tail end of the shield body.

As shown in FIG.
An on-off valve 52 is provided, and a second on-off valve 54 is provided in the curing accelerator feed pipe 44 for intermittent supply of the curing accelerator to the mixer 46 . As the backing material, conventionally well-known backing materials such as mortar or cement suspension containing cement as a main component can be used, and as the hardening accelerator, an aqueous solution of sodium silicate can be used.

Further, a carbon dioxide gas supply pipe 58 extending from a liquefied carbon dioxide pump 56 serving as a carbon dioxide gas source is connected to the mixer 46 . The carbon dioxide gas supply pipe 58 is provided with a third on-off valve 60 for intermittent supply of carbon dioxide gas to the mixer 46.
A heating means 62 such as a heater for promoting vaporization of carbon dioxide gas and a flow rate adjustment valve 64 are provided between the opening/closing valve and the pump 56.

During backfilling, the third on-off valve 60 provided in the carbon dioxide gas supply pipe 58 is closed, and both the first and second valves 52 and 54 are opened, so that the mixer No carbon dioxide gas is supplied to 46,
The backing material and curing accelerator are supplied at a predetermined ratio. Therefore, the backfilling material to which the hardening accelerator has been added and mixed by the mixer is guided through the supply pipe 48 and from its discharge port 50 into the gap between the segment 22 and the excavated surface 38. The backing material to which a curing accelerator has been added starts to gel in 3 to 15 seconds and hardens in about 30 to 60 minutes.

When stopping or stopping the backfilling injection, the first on-off valve 52 provided in the backfilling material feed pipe 42 remains open, but the second on-off valve 52 provided in the hardening accelerator feed pipe 44 remains open. The on-off valve 54 is closed, and the carbon dioxide gas supply pipe 58
The third on-off valve 60 provided at is opened.

As a result, the curing accelerator is not supplied to the mixer, and the backfilling material and carbon dioxide gas are supplied at a predetermined ratio, so that the carbon dioxide gas mixed by the mixer 46 and the backfilling material are supplied to the mixer 46. The mixture with the material is pumped through the supply pipe 48 towards its outlet 50.

When the mixture reaches the discharge port 50 and the supply pipe 48 is filled with the mixture, the first and third on-off valves 52 and 60 are closed, and the second on-off valve 54 is closed.
It is placed in the same closed state.

The mixture in the supply pipe 48, that is, the backfill material to which carbon dioxide gas has been added and mixed, has a pH value of 1, which does not harden due to reaction with carbon dioxide gas, for example, a value of 10 or less.
Since it is lowered, it is filled into the supply pipe 48 without being hardened therein.

The mixture retained in the feed pipe 48 in this uncured state serves to prevent ingress of underground storage through the outlet 50 until backfilling is resumed.

The amount of carbon dioxide required to lower the pH value of the backfilling material to below 1O to keep it in a non-hardened state varies depending on the amount of cement in the backfilling material, but in general, The carbon dioxide gas for the backfilling material is about 3 to 8 liters converted to 1 atm, and the carbon dioxide gas is injected into the mixer 46 through the pre-delivery supply pipe 58 at a pressure of several kg/cm2, so the above-mentioned supply tube 4
The flow rate ratio of the backfilling material and carbon dioxide flowing through 2 and 58 may be set to 1:l.

When backfilling is restarted, as described above, both the first and second valves 52 and 54 are opened while the third on-off valve 60 is closed, and as a result, the mixer 46 is opened. The backing material to which the curing accelerator has been added and mixed is freshly fed under pressure to the supply pipe 48 . When the supply of this new backfilling material is started, the mixture of carbon dioxide gas and backfilling material that has been held in an uncured state in the supply pipe 48 is transferred from the discharge port 50 to the segment 22 and the excavation surface 38. Since the hardening accelerator is released into the gap between and mixed with the sequentially fed backing material to which a curing accelerator has been added and mixed, the pH value thereof is increased to, for example, a value of 11 or more, and it is cured in the gap.

Therefore, a piston for pushing out the backfilling material remaining in the backfilling material supply pipe as in the past is not provided in the supply pipe, and therefore, a cylinder device for operating the piston is provided on the outer periphery of the shield body. Since it is possible to prevent the backfill material from hardening within the supply pipe without using high-pressure water to clean the backfill material supply pipe, it is possible to prevent the hardening of the backfill material within the supply pipe. Furthermore, it is possible to prevent the backfilling material from hardening in the supply pipe without performing any special post-treatment, and thereby the backfilling injection work can be easily restarted.

The first to third on-off valves 52, 54 and 60
are respectively electromagnetic valves, and by continuously controlling the operation of the electromagnetic valves by a control circuit, the above-described series of operations of the respective opening/closing valves 52, 54, and 60 at at least one of the start of backfill injection and the pause of backfilling can be performed. Can be automated. In addition, as a signal when backfilling injection is stopped,
By inputting a stop signal of the shield excavation device 10 to the control circuit, when the excavation work is stopped, the supply pipe 48 is automatically filled with a mixture of carbon dioxide gas and backfilling material, and the backfilling material is also filled. The injection operation can be stopped. Furthermore, by providing a pressure detection means for detecting an abnormal increase in backfilling material injection pressure in the supply pipe, and inputting a signal from the pressure detection means to the control circuit as a signal for stopping backfilling injection. When the backfilling material injection pressure increases abnormally, the inside of the supply pipe 48 can be automatically filled with a mixture of carbon dioxide gas and the backfilling material, and the backfilling material injection operation can be stopped.

In the above, an example was explained in which the supply of the curing accelerator was stopped at the same time as the supply of carbon dioxide gas to the mixer 46 was started. This can coincide with interruptions in the supply of material to the mixer. That is, when the backfilling material injection operation is stopped, the inside of the supply pipe 48 can be filled with a mixture of carbon dioxide gas and the backfilling material to which a curing accelerator has been added. The curing accelerator gels when mixed alone with carbon dioxide gas, but does not gel when added to and mixed with the backing agent. Therefore, the mixture does not contain the curing accelerator. It exhibits the same action and effect as the above-mentioned mixture of backfilling material and carbon dioxide gas that does not contain it. However, in order to reliably prevent an unexpected reaction between the curing accelerator and carbon dioxide gas in the mixer 46, it is necessary to start supplying the curing accelerator to the mixer 46 at the same time as the supply of carbon dioxide gas starts. Preferably, the feed is stopped.

Further, in the above description, an example was explained in which a mixture of the backfilling material and carbon dioxide gas is filled in the backfilling material supply pipe that guides the backfilling material to which a curing accelerator has been added. The supply pipe can be filled with a mixture of backfill material and carbon dioxide gas to prevent hardening of the backfill material in the pipe which extends through the body into the gap between the ground and the segment.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view schematically showing a shield excavation device to which the method according to the present invention is applied, and FIG. 2 is a block diagram schematically showing the backfilling injection device shown in FIG. 1. . 10: Shield drilling equipment, 12: Shield main body, 22: Segment, 46: Mixer, 48: Backfilling material supply pipe. 50: Release port. Agent Patent Attorney Nobuyuki Matsunaga Figure 1 Figure 2

Claims (5)

[Claims] (1) As the shield body moves forward, backfill material is added to the part leading to the discharge port of the backfill material supply pipe for guiding the backfill material into the gap between the segment placed behind the shield body and the ground. A method for preventing hardening of a backfill material, which is characterized by filling a mixture of carbon dioxide gas and a backfill material containing a cement component during a pause in material injection. (2) The method for preventing hardening of a backfill material according to claim (1), wherein the backfill material is mortar. (3) The method for preventing curing of a backfilling material according to claim (1), wherein a curing accelerator is added to the backfilling material. (4) The backfilling material supply pipe extends outward from the shield body from a mixer for mixing the hardening accelerator with the backfilling material, and the carbon dioxide gas is mixed with the backfilling material in the mixer. The method for preventing hardening of a backfill material according to claim (3), wherein the method is mixed. (5) The method for preventing hardening of a backfill material according to claim (3), wherein the hardening accelerator is sodium silicate.