JPH0325600B2 - - Google Patents

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.

This is an economical so-called cast-in-place lining construction method that does not use segments, which account for 20 to 30% of the shield construction cost, and also eliminates backfilling and pours lining concrete directly at the tail of the shield. Various construction methods have been devised and implemented. The main types of shield machines used in this construction method include blade shield machines (Metsusel shield machines) belonging to self-propelled shield machines, gripper type shield machines, and propulsion jack type shield machines.

The blade shield machine has sheet piles called blades arranged around the tunnel outer circumference, a supporting frame that supports the blades, and a pushing frame that moves the blades forward.The forward motion of the machine is achieved by taking the reaction force from the thrust force from the segments. Unlike a shield tunneling machine, 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 using a jack to absorb the reaction force on the pushing frame. When the advancement of all the blades is completed, the supporting frame and the pushing frame are advanced by jacking, and this is repeated to advance the blade.

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, construction on curved sections is easy. However, the problem is that the machine has multiple structures and is expensive.

In addition, the gripper-type shield machine divides the excavator into front and rear parts, and attaches grippers operated by gripper jacks to the divided front and rear parts, respectively, and propels the machine to the joint part of both bodies. It is equipped with a jack.

The aircraft moves forward on its own by alternately operating the grippers and propulsion jacks in the divided front and rear bodies, much like an inchworm moves forward.

The gripper-type shield machine, which 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, just like the blade shield machine, but on the other hand, the machine Since the fuselage is divided into a front body and a rear body, the length of the aircraft becomes long, making it difficult to construct curved sections.In addition, if the ground is soft, for example, the gripper effect that fixes the aircraft to the ground becomes difficult. In addition, because the overall length of the aircraft is long, it is heavy, and the structure is complex and expensive.

Furthermore, the propulsion jack type shield machine has a structure that is almost the same as 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 it is lighter in weight and has a simpler structure. 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, 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 hardens requires time for the lining concrete to harden, which reduces the excavation speed. On the other hand, the method of propelling the concrete before it hardens is faster than the method of pushing after the concrete hardens, but it has a negative effect on the lining concrete because it applies a fluctuating jacking thrust to the concrete during setting.

There is also a method of making the push rod bear the propulsion reaction force. In the case of this method, the excavation speed is approximately the same as the propulsion before the concrete hardens, but if partial pressure is applied to the push rod when constructing a curved section, the push rod will be displaced, which will have an adverse effect on the concrete during setting. In addition, the push 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 excavation speed can be increased.

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

(3) Do not use push rods, etc. as a means of receiving reaction force.

etc. are mentioned.

In order to increase the excavation speed, it is necessary to use concrete with early strength. The reason for this is that the concrete can be moved immediately after it hardens, and the formwork only requires a short length of time. Regarding this early-strengthening concrete, it is generally not possible to increase the compressive strength to about 100 kg/cm ² within 1 to 2 hours after concrete pouring using only the early-strengthening admixtures that are commercially available as concrete admixtures. 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 time. However, because the thrust fluctuates due to changes in the shield machine's cutting edge resistance, changes in the surrounding 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 increases. If this occurs, there is a risk that the lining concrete, which has been cured to some extent, may be destroyed. Therefore, it is necessary to apply a certain pressing pressure to the poured concrete.
The main causes of cracks in concrete after hardening are:
Because early-strengthening concrete is used, it generates a large amount of heat and is rapidly cooled after hardening, resulting in temperature changes.In the case of unreinforced lining concrete, bending and tensile stress is applied to the concrete due to load conditions. However, such cracks in concrete are caused by applying prestress to the unhardened lining concrete by applying a press pressure that takes into account the elastic modulus of the ground. Cracks due to bending and tensile stress caused by loads applied to the tunnel can be prevented.

The present invention has been proposed in view of the above points, and its objectives are to increase the excavation speed by increasing early strength, to prevent wave breaking of hardening concrete, and to prevent lining concrete from setting when it is unset. The propulsion method is capable of preventing underground water leakage and cracking of the lining concrete after hardening, and the propulsion jack-type shield machine, which is suitable for this method, is short in length and lightweight. The object of the present invention is to provide a shield tunnel excavation device that is light, has a simple structure, and is 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 lining concrete bears the propulsion reaction force for excavation, and the cast lining concrete is processed. A pressure jack that presses the lining concrete and a propulsion jack that pressurizes the formwork of the lining concrete are used in combination. Immediately after the lining concrete is placed, the pressure jack is applied while the concrete maintains its fluidity. At the same time, the lateral pressure applied to the formwork by this pressurization is measured with a lateral pressure gauge to control the thrust of the pressurizing jack, and the thrust obtained by subtracting the thrust of the pressurizing jack from the thrust is applied to the propulsion jack. This thrust force is applied to the gripper via the formwork and the slide jack of the formwork to perform excavation.

Further, the shield tunnel excavation device of the present invention includes:
In a shield tunnel excavation device that casts lining concrete at the tail of the shield and uses this lining concrete to bear the propulsion reaction force for propulsion, a pressurizer installed on the tail of a ring girder attached to the shield body is used. a jack and a propulsion jack; a press ring attached to the pressure jack to pressurize the poured concrete; a formwork for pouring concrete connected to the propulsion jack; attached to the frame,
and a lateral pressure gauge for measuring lateral pressure for controlling the thrust of the pressure jack, a gripper for bearing the thrust of the propulsion jack, and a formwork slide jack installed between the gripper and the formwork. It is characterized by having the following.

Further objects and features of the invention 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, 1 is the ground to be excavated, 2 is the shield body, 3 is the skin plate provided on the outer periphery of the shield body, 4 is the ring girder attached to the rear of the shield body 2, 5 is the shield tail part, 6 and 7 are pressure jacks and propulsion jacks attached to the tail part of the ring girder 4,
As shown in FIG. 2, a plurality of pressure jacks 6 are provided at equal intervals around the circumference so that their centers are located at the center of the thickness of the lining concrete 8, and the propulsion jacks 7 are used for pouring concrete. As shown in FIG. 2, a plurality of pressure jacks 6 are located at the center of the formwork 9 on the inner circumferential side of the pressure jacks 6 and between the pressure jacks 6 at equal intervals around the circumference.

Numeral 10 is a press ring attached to the pressure jack 6 to prevent leakage of poured concrete and to pressurize the concrete. Numeral 11 is a press ring attached to the presser jack 6 at multiple locations on the circumference of the formwork 9 (as shown in FIG. 3). In the example, lateral pressure gauges are installed at four locations in the formwork 9 to measure the lateral pressure applied to the formwork 9 and control the thrust of the pressurizing jack 6, 12 is a concrete pouring port provided in the formwork 9, and 13 is a concrete This is a pipe connected to the pouring port 12, and is connected to a concrete pump (not shown). Reference numeral 14 denotes a gripper for receiving the thrust of the propulsion jack 7, and as shown in FIG. 4, a gripper jack 15 for expanding or contracting the gripper on the lining concrete 8 is provided. 16 is gripper 14
This is a formwork slide jack mounted on the gripper 14 so as to be located between the formwork 9 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 the hydraulic oil supplied from the hydraulic pump 17 via a manual pressure regulating valve 18, and by controlling the pressure of the hydraulic oil supplied from the hydraulic pump 17 via a switching valve 19. The pressure jack 6 is extended by supplying it to the pressure jack 6,
Immediately after placing the lining concrete, the concrete is pressurized by the pressure jack 6, and the hydraulic pressure is read by the hydraulic 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. By maintaining this hydraulic pressure with a pressure regulating valve, the concrete placed this time is pressurized.

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

First, the gripper jack 15 is contracted to release the gripper 14 from the lining concrete 8, and then the formwork slide jack 16 is contracted and the gripper jack 15 is extended to press the gripper 14 onto the lining concrete 8. Fix it.

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 one hour or more after mixing the concrete), the pressure jack 6 is contracted and concrete is poured from the concrete pouring port 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 and promotion work must be carried out while the poured concrete maintains its fluidity, and this is because the lining concrete 8 must be brought into complete contact with the ground 1.

The pressure applied to the lining concrete 8 is set based on the elastic modulus and strength of the ground 1. This pressure measurement is performed by reading the lateral pressure applied to the formwork 9 with a lateral pressure gauge attached to the formwork 9 immediately after concrete is poured, with the concrete maintaining its fluidity being pressurized by the pressure jack 6. Excavation work is carried out by keeping the pressing force at which the lateral pressure has reached the set value constant for the length of the concrete currently cast.

The reasons for carrying out excavation propulsion with a constant lateral pressure are: (1) to ensure that the lining concrete adheres completely to the inner surface of the excavated earth, (2) to avoid applying excessive thrust to the previously placed lining concrete, ( 3) Preventing water leakage when the lining concrete is unset, and (4) Preventing cracking by applying prestress to the lining concrete taking into account the elastic modulus of the ground.

As mentioned above, the method of pressurizing with a constant lateral pressure is to pressurize the concrete with the pressure jack 6 immediately after placing the lining concrete, and set the average value of only the plurality of lateral pressure gauges 11 attached to the formwork 9. The oil pressure that has reached this value is read by the oil pressure gauge 20, and this oil pressure is maintained by the pressure regulating valve 18 to increase the pressure.

According to experiments, the reason for measuring the set value immediately after pouring the lining concrete and applying constant pressure is as follows.
This is because the lateral pressure of concrete gradually decreases immediately after pouring, and by the time concrete begins to set, the lateral pressure has decreased to about 40%.

Furthermore, if the lining concrete is constructed with a constant mixture, it is possible to perform construction 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 applied 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 does not use segments that account for 20 to 30% of the shield construction cost, omits backfill injection and secondary lining, and is generally In addition to making it possible to make the inner hollow cross section smaller because no segments are used in the same inner cross section compared to the shield of In addition, by utilizing the elastic modulus of the excavated ground, it gives prestress to the lining concrete, thereby preventing cracks caused by temperature changes and cracks caused by bending and tensile stress caused by loads applied to the tunnel. be able to.

Furthermore, according to the present invention, by using the above construction method, it is possible to obtain a suitable 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 cross-sectional view of a shield tunnel excavation device according to the present invention, FIG. 2 is a cross-sectional view taken along the line A-A in FIG. 1, and FIG. 3 is a cross-sectional view taken along the line B-B in FIG. Fourth
The figure is a sectional view taken along the line CC in FIG. 1, and FIG. 5 is a hydraulic control circuit diagram of the pressurizing jack. 1... Earth, 2... Shield body, 4... Ring girder, 5... Tail part, 6... Pressure jack, 7... Propulsion jack, 8... Lining concrete, 9... Formwork, 10 ...press ring,
11...Side pressure gauge, 14...Gripper, 16...
Formwork slide jack, 18...pressure adjustment valve.

Claims (1)

[Scope of Claims] 1. In the shield tunnel excavation method in which lining concrete is cast at the tail portion of the shield and the tunnel is excavated by bearing the propulsion reaction force with this lining concrete, the cast lining concrete is pressurized. It uses a pressure jack and a propulsion jack that pressurizes the formwork of the lining concrete. Immediately after the lining concrete is placed, the pressure jack is used while the concrete maintains its fluidity. At the same time as pressurizing, the lateral pressure applied to the formwork due to this pressurization is measured with a lateral pressure gauge to control the thrust of the pressurizing jack, and a thrust obtained by subtracting the thrust of the pressurizing jack from the thrust is applied to the propulsion jack. A method for excavating a shield tunnel, characterized in that the thrust force is applied to a gripper via the formwork and a slide jack of the formwork for excavation. 2 The oil pressure when the average value of the multiple lateral pressure gauges attached to the formwork reaches the set value is read with a hydraulic pressure gauge, and this oil pressure is maintained with a pressure regulating valve to keep the side pressure applied to the formwork constant. The shield tunnel excavation method according to claim 1, characterized in that the shield tunnel excavation method is controlled to: 3. A patent claim characterized in that excavation is temporarily interrupted while the pressure jack is operated, and the propulsion jack and the formwork slide jack are alternately operated to cause the formwork to slide back and forth. Range 1
Shield tunnel excavation method described in section. 4. In a shield tunnel excavation device that casts lining concrete at the tail of the shield and excavates by bearing the propulsion reaction force with this lining concrete,
a pressure jack and a propulsion jack attached to the tail of a ring garter attached to the shield body; a press ring attached to the pressure jack and pressurizing the poured concrete; and a press ring connected to the propulsion jack. a formwork for pouring concrete; a lateral pressure gauge that is attached to the formwork and measures lateral pressure for controlling the thrust of the pressure jack; a gripper that bears the thrust of the propulsion jack; A shield tunnel excavation device comprising a formwork slide jack installed between the formwork and the formwork.