JPS6023597A - Shield tunnel drilling method and apparatus - 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] The present invention relates to a shield tunnel excavation method in which lining concrete is cast at the tail portion of the shield, and this lining concrete bears the propulsion reaction force for excavation, and a shield tunnel excavation method used in the construction of the same method. This relates to propulsion devices.

The segment, which accounts for 20 to 30% of the shield construction cost, is not used, and backfill injection is also omitted.

Various methods have been devised and implemented for the economical so-called cast-in-place lining method, in which lining concrete is poured directly at the tail portion of the shield.

The main shield machines used in this construction method are:
There are blade shield machines (Metsu cell shield machines), gripper set shield machines, propulsion jack type shield machines, etc. that belong to self-propelled shield machines.

The blade shield machine has sheet piles called blades arranged around the tunnel outer periphery, a supporting frame that supports the blades, and a bushing frame that moves the blades forward. Unlike an excavator, this machine utilizes the frictional force between the blades and the ground around the machine body. First, from the top of the tunnel, the same number of blades on the left and right sides are moved forward with a jack by absorbing the reaction force against the bushing frame. When the advance of each blade is completed, the supporting frame and the pushing frame are used to move the blade forward, and this process is repeated to move the blade forward.

This blade shield machine has good excavation efficiency because the excavation work is not restricted to backward work such as lining, and by changing the overhang length of the left and right blades,
Although it has features such as ease of construction on curved sections, it has the problem that the machine has multiple structures and is expensive.

In addition, the gripper set shield machine is a machine that divides the excavator into front and rear parts, and installs a gripper in the divided front body and rear body.
The gripper operated by the jacks can be seen, and the propulsion jacks are attached to the joints of both bodies.

The aircraft moves forward on its own by alternately operating grippers and propulsion jacks on the divided front and rear bodies, much like an inchworm moves forward. Similar to the blade shield machine, the gripper-shield machine that moves the machine forward in this way is characterized by good excavation efficiency because the excavation work is not restricted to backward-facing work such as lining, but on the other hand, Since the fuselage is divided into a front body and a rear body, the length of the fuselage becomes long, making it difficult to construct curved sections.In addition, if the soil of the ground is soft, for example, grippers to fix the fuselage to the ground are required. - It may not be as effective as expected, and furthermore, because the overall length of the aircraft is long, the amount of balls is large, and the structure is complicated and expensive.

Further, the propulsion jack-type shield machine has a structure that is almost the same as that of a commonly used shield excavator, and differs from the above two types in that the propulsion reaction force is borne by the cast-in-place lining.

As is clear from the shielding results to date, this propulsion jack-type shield machine is easy to construct curves, and compared to blade shield machines and gripper shield machines, the machine length is shorter, so the weight is lighter, and the structure is simpler. It has the characteristics of being simple and inexpensive.

However, since the cast-in-place lining bears the propulsion reaction force, problems arise with the lining. This point will be explained below.

First, there is a method in which the propulsion reaction force is borne by cast-in-place lining concrete, and the propulsion is carried out after the concrete has hardened.
Excavation speed decreases because it takes time for lining concrete to harden. On the other hand, the method of propelling the concrete before it hardens is faster than the method of propelling it after the concrete has hardened, but the concrete is still setting.

It applies a fluctuating jacking thrust to the concrete, which has an adverse effect on the lining concrete.

There is also a method of making the bush rod bear the propulsion reaction force. In the case of this method, the excavation speed is approximately the same as the propulsion speed before the concrete hardens, but if partial pressure is applied to the bush rod during construction of a curved section, the bush rod is displaced and the concrete is set. This can have negative effects and the bushing rod is heavy and expensive. The propulsion jack type shield machine has not been widely used to date because of the problems mentioned above.

The conventional techniques have been examined above, and although each machine has its advantages and disadvantages, the propulsion jack type is the best in terms of the structure of the excavator. The reasons for this are that, as mentioned above, the structure is simple, the price is low, and the machine length is short, making it easy to construct curves.

However, since shielding reaction force is required, it is necessary to use a propulsion jack type cast-in-place lining method.

The necessary conditions in this case are: (1) The speed of excavation can be increased.

(2) The lining is less prone to cracking after hardening.

(3) For example, do not use a bushing rod or the like as a means for receiving reaction force.

etc. are mentioned.

In order to increase the excavation speed, it is necessary to use concrete with early strength. The reason is that after concrete hardens,
This is because immediate propulsion is possible and the extension of the formwork can be shortened. Regarding this early-strengthening concrete, generally, with only the early-strengthening admixture commercially available as a concrete admixture, the compressive strength cannot be increased to about 100 kg/ctri' within 1 to 2 hours after concrete placement. It is difficult. Therefore, it is necessary to use the thrust of the propulsion jack to pressurize the poured concrete to increase its strength in a short period of time. However, because the thrust fluctuates due to changes in the shield machine's cutting edge resistance, changes in the peripheral friction of the shield machine, etc., there is a risk of having an adverse effect on the unhardened lining concrete, and the thrust of the shield machine becomes large. If this occurs, there is a risk that the lining concrete, which has already been hardened, may be destroyed. Therefore, it is necessary to apply a certain pressing pressure to the poured concrete. The main cause of cracks in concrete after hardening is that early-strengthening concrete is used, which generates a large amount of heat, and is rapidly cooled after hardening, resulting in temperature changes. These cracks in concrete are caused by bending and tensile stress being applied to the lining concrete, which is caused by applying press pressure that takes into account the elastic modulus of the ground to the unhardened lining concrete. By applying prestress, it is possible to prevent cracking due to tensile stress inside the concrete due to temperature changes and bending tensile stress caused by loads applied to the tunnel.

The present invention was proposed in view of the above points, and its objectives are to accelerate the excavation speed by increasing early strength, to prevent the destruction of hardening concrete, and to prevent lining concrete from setting when it is not set. The machine is short in length and light in weight, taking advantage of the propulsion method that can prevent underground water leakage and cracking of lining concrete after hardening, and the propulsion jack type shield machine that is suitable for this method. To provide a shield tunnel excavation device that is light, simple in structure, and inexpensive.

The shield tunnel excavation method of the present invention is a shield tunnel excavation method in which lining concrete is cast at the tail part of the shield and the tunnel is excavated by bearing the propulsion reaction force with this lining concrete. A pressure jack and a propulsion jack are used together, and the thrust of the pressure jack is measured and controlled by the side pressure applied to the formwork for concrete to be cast, and the thrust is calculated by subtracting the thrust of the pressure jack from the total thrust. The thrust force is transferred to the gripper via the formwork and the slide jack of the formwork.
It is characterized by the fact that it excavates by placing the burden on the excavator.

Further, the shield tunnel excavation device of the present invention is a shield tunnel excavation device in which lining concrete is cast at the tail portion of the shield, and the lining concrete bears the propulsion reaction force for propulsion.

A pressure jack and a propulsion jack are attached to the tail portion of a ring girder attached to the shield body, a press ring is attached to the pressure jack and pressurizes poured concrete, and a press ring is connected to the propulsion jack. a formwork for pouring concrete, a lateral pressure gauge attached to the formwork that totals the lateral pressure applied to the formwork to control the thrust of the pressure jack, and a gripper that bears the thrust of the propulsion jack. , a formwork slide jack mounted between the gripper and the formwork.

Further objects and features will become apparent from the embodiments of the invention described below.

FIG. 1 is a sectional view of the shield tunnel excavation device. In the figure, ■ is the ground to be excavated, 2 is the shield body,
3 is a scombrate provided on the outer periphery of the shield body,
4 is a ring girder attached to the rear of the shield body 2, 5 is a shield tail portion, and 6 and 7 are ring girders.
The pressure jacks 6 are installed at the tail part of the lining concrete 8 and the 4ft forward jacks, and the pressure jacks 6 are arranged at equal intervals around the circumference as shown in FIG. As shown in FIG. 2, the propulsion jack 7 is located at the center of the formwork 9 for pouring concrete, on the inner peripheral side of the pressure jack 6.
A plurality of them are located between the pressure jacks 6 at equal intervals around the circumference.

10 is a press ring that is attached to the pressure jack 6 to prevent leakage of poured concrete and pressurizes the concrete; 11 is a press ring attached to the pressure jack 6 at multiple locations on the circumference of the formwork 9 (as shown in FIG. 3); In the example, it is attached at four locations),
A lateral pressure gauge measures the lateral pressure applied to the formwork 9 and controls the thrust of the pressurizing jack 6, 12 is a concrete pouring port provided in the formwork 9, and 13 is a pipe connected to the concrete pouring port 12. , which is connected to a concrete pump (not shown). Numeral 14 denotes grits for receiving the Ht force of the propulsion jack 7, and as shown in FIG. We are prepared. 1B is a formwork slide jack mounted on the gripper 14 so as to be located between the grits 14 and the formwork 9.

Further, as shown in FIG. 5, the pressurization control of the pressurizing jack 6 is performed by adjusting the pressure of hydraulic oil supplied from the hydraulic pump 17 via a manual pressure regulating valve 18. The pressurizing jack 6 is extended by supplying the pressurizing jack 6 through the switching valve 18, and immediately after the inning concrete is poured, the pressurizing jack 6 is used to extend the concrete. Pressurize,
By reading the oil pressure with the oil/pressure gauge 20 when the average value of the readings of the plurality of side pressure gauges 11 attached to the formwork 9 reaches the set value P1, and maintaining this oil pressure with the pressure regulating valve. The structure is designed to apply pressure to the concrete that has been poured this time.

Next, the procedure for excavation using the apparatus configured as described above will be explained.

First, the gripper jaw 15 is contracted to release the gripper 14 from the lining concrete 8, and then the formwork slide gear 15 is contracted to release the gripper 14 from the lining concrete 8. Contract the lever 16 and use the gripper.
The jack 15 is extended to press and fix the gun 1-14 to the lining concrete 8.

Next, the propulsion jack 7 is contracted and at the same time the formwork propulsion jack 16 is extended to send the formwork 9 forward.

After the previously placed lining concrete 8 starts to set (approximately 1 hour after mixing the concrete - 1), the pressure jack 6 is contracted and concrete is poured from the concrete pouring opening 12 provided in the formwork 9. . Immediately after concrete is placed, pressure is applied by the pressurizing jack 6, and this is used in combination with the propulsion jack 7 to start excavation propulsion. The excavation promotion work must be carried out while the poured concrete maintains its fluidity.
This is because it is necessary to completely adhere to the

The pressure applied to the lining concrete 8 is set based on the elastic modulus and strength of the ground l. The measurement of this pressing force is
Immediately after concrete was poured, the lateral pressure applied to the formwork 9 with the fluidity maintained concrete pressurized by the pressure jack 6 was read with a lateral pressure gauge attached to the formwork 9, and the lateral pressure reached the set value. Excavation is carried out with the pressing force constant for the length of the concrete that has been placed this time.

The reasons for promoting excavation with a constant lateral pressure are (1) to ensure that the lining concrete adheres completely to the inner surface of the excavated ground, (2) to avoid applying excessive thrust to the previously placed lining concrete, ( 3) Preventing water leakage when the lining concrete is unset; (4) By applying prestress to the lining concrete in consideration of the elastic modulus of the ground.

Preventing cracks; It is in.

As mentioned above, the method of pressurizing while keeping the lateral pressure constant is to pressurize the concrete with the pressure jack 6 immediately after placing the lining concrete 1, and calculate the average of only the lateral pressure gauges 11 attached to the formwork 9. The oil pressure when the value reaches the set value is read by the oil pressure gauge 20, and this oil pressure is maintained by the pressure 18 to increase the pressure.

The reason for measuring the set value immediately after placing the lining concrete and applying constant pressure is that, according to experiments, the lateral pressure of the concrete gradually decreases from immediately after the lining concrete is placed, and by the time the concrete starts setting, the lateral pressure is 40%. This is because it decreases to a certain extent.

Furthermore, if the lining concrete is constructed with a constant mixing ratio of 1, construction can be performed with a nearly constant pressing force as long as there is no change in the ground.

In addition, in order to prevent the lining concrete from adhering to the formwork, excavation propulsion is temporarily suspended while the pressure jack 6 is operated, and the formwork slide jack 16 and propulsion jack 7 are operated alternately to remove the mold. The frame 9 may be slid back and forth.

Since the thrust of the pressure jack 6 alone is insufficient, the thrust of the propulsion jack 7 is used in combination to propel the excavation. At this time, the thrust of the propulsion jack 7 is transmitted to the formwork 9, and is further transferred to the gripper 14 via the formwork slide jack 16. After completing the excavation for the current pouring, excavation is carried out by repeating the above-mentioned work.

As is clear from the embodiments described above, the shield tunnel excavation method of the present invention has a cost of 20% to 20% of the shield construction cost.
It does not use segments that account for 30% of the shield, eliminates backfill injection and secondary lining, and does not use segments for the same internal cross section compared to general shields, making it possible to make the internal cross section smaller. In addition, by applying a certain pressing pressure to the lining concrete, it is possible to increase early and long-term strength, and by utilizing the elastic modulus of the excavated ground, it is possible to give pressure stress to the lining concrete, thereby reducing temperature changes. It is possible to prevent cracks caused by bending and tensile stress caused by the load applied to the l-channel.

Furthermore, according to the present invention, using the above construction method, suitable
It is possible to obtain a shield tunnel excavation device that is short in length, light in weight, simple in structure, and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a shield tunnel excavation device according to the present invention, and FIG. 2 is a sectional view taken along the line A-A in FIG. 1. 3 is a sectional view taken along the line BB in FIG. 1, FIG. 4 is a sectional view taken along the line CC in FIG. 1, and FIG. 5 is a hydraulic control circuit diagram of the pressure jack. l... Earth, 2... Shield body. 4...Ring girder-95...Tail part. 6... Pressure jack, 7... Propulsion jack. 8...Lining concrete, 9...Formwork. lO...press ring, 11...lateral pressure needle. 14...Gripper-9 1B...Formwork slide jack. 18...Pressure regulating valve. Applicant Kumagai Gumi Co., Ltd. Agent Patent attorney Funabashien side Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

Claims (1)

[Claims] 1. Placing lining concrete at the tail portion of the shield,
In the shield tunnel excavation method in which tunneling is carried out by bearing the propulsion reaction force using this lining concrete, a pressure jack that pressurizes the poured concrete and a propulsion jack are used together,
The thrust of the pressure jack is controlled by measuring the lateral pressure applied to the formwork for concrete to be cast, and the propulsion jack is borne by the thrust force obtained by subtracting the thrust of the pressure jack from the total thrust, and this thrust is applied to the formwork. and a shield tunnel excavation method characterized in that excavation is carried out by placing the load on a gripper via a slide jack of the same formwork. 2. The shield tunnel according to claim 1, wherein after placing the lining concrete, while the concrete maintains its fluidity, pressure is applied by a pressure jack to start excavation. Excavation method. 36. The shield tunnel excavation method according to claims 1 and 2, wherein the lateral pressure applied to the formwork is controlled to be constant. 4. The shield tunnel excavation method according to claim 3, wherein the set value of the lateral pressure is set based on the strength of the ground. 5. A patent claim characterized in that excavation is temporarily interrupted while the pressure jack is operated, and the propulsion jack and the slide jack of the formwork are operated alternately to slide the formwork back and forth. Scope: The shield tunnel excavation method described in item 1. 8. Place lining concrete at the tail of the shield,
In the excavation method, the shield body excavates by bearing the propulsion reaction force with this concrete lining. A press ring is attached to a jack and pressurizes the poured concrete, a formwork for placing concrete is connected to the propulsion jack, and a press ring is attached to the same formwork to measure the lateral pressure applied to the formwork and pressurize the poured concrete. A side pressure gauge that controls the thrust of the pressure jack,
A shield tunnel excavation device comprising: a gripper that bears the thrust of the propulsion jack; and a formwork slide jack installed between the gripper and the formwork. 7. A shield tunnel excavation device 8 according to claim 1, characterized in that a plurality of the lateral pressure gauges are provided and the pressure jack is controlled by the average value of the lateral pressure gauges, and the lateral pressure measured by the lateral pressure gauges is installed. The shield tunnel excavation apparatus according to claim 1, wherein the pressurizing jack is controlled by adjusting the hydraulic pressure supplied to the pressurizing jack using a regulating valve so that the pressure jack is adjusted to the pressure jack.