JP2012122259A - Soil discharge device for mud pressure shield machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil discharge device for a mud pressure shield machine capable of securing mud pressure to resist against an earth pressure of a face and executing a tunneling work even for natural ground with many boulders clustered therein in no way inferior to tunneling a general gravel layer subject to use of a ribbon type shaftless screw conveyor which can convey the boulders.SOLUTION: A soil discharge device for a mud pressure shield machine comprises: a ribbon type shaftless screw conveyor 8 which is connected to a cutter chamber, has a maximum conveyable gravel diameter equal to or larger than a radius (D2/2) of a conveyance path 31, and conveys excavated soil including a gravel fraction from a cutter chamber; and a soil removing pipe 25 which is connected to the screw conveyor, has the conveyance path 35 with a diameter (D1) smaller than the diameter of the conveyance path of the screw conveyor, and has a length longer than the length where a plug zone is formed by a pressure loss of the excavated soil to be conveyed.

Description

  The present invention is a ground where a large amount of boulders are scattered, and it is possible to secure a mud pressure against the face soil pressure on the premise that a ribbon type shaftless screw conveyor capable of conveying boulders is used. In particular, the present invention relates to a sediment discharge device for a mud pressure shield excavator that can perform excavation work as well as excavating a general gravel layer or the like.

  In general, the mud pressure shield construction method uses a shield jack to propel a shield machine and, along with this propulsion, excavates the face of a natural ground with a rotary cutter in front of the shield machine. The excavated earth and sand are filled in the cutter chamber behind the rotary cutter and the screw conveyor for discharging the soil from the cutter chamber.

  At this time, the additive material is injected into the front surface of the rotary cutter or the cutter chamber. The additive is kneaded into the excavated earth and sand, and the earth and sand is converted into mud that is rich in plastic fluidity (property of being freely deformable and movable) and exhibits impermeability.

  Mud is filled from the cutter chamber to the screw conveyor, and the mud pressure that opposes the earth pressure and groundwater pressure (hereinafter referred to as “face earth pressure”) of the face due to the thrust of the shield jack. Will occur.

  In order to maintain a balance between the mud pressure and the face pressure, the balance of the propelling amount of the shield machine and the amount of soil discharged by the screw conveyor is used to dig while keeping the face stable. .

  By adding additives to the excavated soil and making mud with plastic fluidity and imperviousness, smooth drainage by the screw conveyor is ensured, and a plug zone (water stoppage area) is provided in the screw conveyor. It is formed to prevent groundwater eruption.

  This kind of mud pressure shield earth and sand discharging device is disclosed in Patent Document 1, for example. The “earth pressure bubble shield digging device” of Patent Document 1 is formed between a cutter head provided at the front of the shield body, a partition provided behind the cutter head, and the cutter head and the partition. A bubble conveyor that penetrates the partition and inserts a tip opening into the earth pressure chamber, and injects bubbles projecting into the earth pressure chamber through the partition; A soil removal transport pipe for liquid-tightly connecting a soil discharge port provided at a rear portion of the screw conveyor and a hopper installed outside the mine shaft, and the soil discharge transport pipe in the vicinity of the soil discharge port. And a pumping pump that continuously pumps the digging earth and sand with bubbles toward the hopper. In patent document 1, earth and sand are discharged | emitted with the screw conveyor with a shaft which has a rotating shaft in the center.

JP-B-1-37560

  By the way, when the ground is a geology in which many boulders such as boulders whose outer dimensions exceed φ500 are scattered and other boulders or gravels are included, such boulders have a rotation axis in the center. In general, it is impossible to convey the inner diameter of a general screw conveyor with a shaft for a shield machine, and it is inefficient and unrealistic to dig the boulder into small pieces.

  Adopting a ribbon type shaftless screw conveyor is conceivable for conveying boulders. The ribbon-type shaftless screw conveyor has spiral blades continuously provided in the length direction of the inner cylinder on the inner peripheral surface of the inner cylinder that is rotationally driven. Thereby, if a center rotating shaft is abolished and it is smaller than the internal diameter of the inner cylinder used as a conveyance path, even if it is a boulder, it can be conveyed.

  However, unlike a screw conveyor with a shaft, a ribbon type screw conveyor without a shaft cannot convey excavated earth and sand in a dense state. In particular, in excavated earth and sand containing boulders, the pressure in the transport path is extremely unstable because the boulders move away from the excavated earth and sand in an unstable manner.

  In this way, when excavated sediment cannot be transported in a solid state and the pressure in the transport path is unstable, the mud pressure across the screw conveyor from the cutter chamber to the screw conveyor is properly controlled even if the rotation speed of the screw conveyor is controlled. It is difficult to secure, and therefore, it is difficult to maintain equilibrium with the face pressure, and the mud pressure shield method cannot be safely constructed.

  That is, in the ribbon-type shaftless screw conveyor, a plug zone that becomes a water stop region and opposes the face soil pressure cannot be secured appropriately. In particular, when the groundwater pressure is high, the adoption of the ribbon type shaftless screw conveyor has been a problem in construction.

  The present invention was devised in view of the above-described conventional problems, and on the premise of using a ribbon type shaftless screw conveyor capable of transporting boulders, it is possible to secure a mud pressure that opposes the face soil pressure. Provide a mud pressure shield excavator earth and sand discharging device that can perform excavation work as well as excavating ordinary gravel layers etc. even if it is a natural mountain where many boulders are scattered The purpose is to do.

  A mud pressure shield excavator earth discharge device according to the present invention excavates from a face by a rotary cutter and is crushed, and excavated earth and sand including gravel filled in a cutter chamber behind the rotary cutter is applied to the face pressure. In the mud pressure shield excavator earth discharging device that discharges from the cutter chamber to the outside, the excavated earth and sand connected to the cutter chamber and having a maximum transportable gravel diameter equal to or greater than the radius of the transport path and including gravel A ribbon type screwless screw conveyor that conveys from the cutter chamber, and a conveying path that is connected to the screw conveyor and is set to a diameter smaller than the diameter of the conveying path of the screw conveyor. And a drainage pipe set longer than the length of the plug zone formed by pressure loss. That.

  The discharge pipe is connected to an air supply pipe for supplying air to the carry-out path in order to adjust the fluidity of excavated sediment.

  A water supply pipe for supplying water to the carry-out path is connected to the soil discharge pipe in order to adjust the fluidity of excavated sediment.

  In the mud pressure shield excavator according to the present invention, it is possible to secure the mud pressure against the face earth pressure on the premise that a ribbon type shaftless screw conveyor capable of conveying boulders is used. It is possible to carry out the excavation work in the same way as excavating a general gravel layer or the like even in a natural ground where many boulders are scattered.

It is a schematic sectional side view which shows one suitable embodiment of the earth-and-sand discharge apparatus of the mud pressure shield machine according to the present invention. It is a front view of the rotary cutter of the mud pressure shield machine shown in FIG. It is a schematic sectional drawing which shows the ribbon type shaftless screw conveyor of the earth-and-sand discharge apparatus of the mud pressure shield machine shown in FIG. It is a principal part side view of the connection part of the ribbon type screwless screw conveyor shown in FIG. 3 and a soil discharge pipe. In FIG. 4, it is an A direction arrow directional view. It is a graph which shows the particle size accumulation curve of a suitable natural ground by applying the earth and sand discharging apparatus of the mud pressure shield machine according to the present invention.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, a preferred embodiment of a mud pressure shield excavator earth and sand discharging apparatus according to the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows a schematic side view of the sediment discharge device 30 of the mud pressure shield machine 1 used in the mud pressure shield method according to the present embodiment, and FIG. 2 shows the mud pressure shield machine 1 of the mud pressure shield machine 1. A front view of the rotary cutter 2 is shown.

  The mud pressure shield machine 1 is mainly provided with a hollow cylindrical skin plate 3, a partition wall 4 provided on the front end side of the skin plate 3, and spaced forward from the partition wall 4. A rotary cutter 2 that is rotated by an unillustrated excavator to cut a natural face Z, a cutter chamber 5 that is formed between the rotary cutter 2 and the partition wall 4 and into which the excavated earth and sand are taken in, and the cutter chamber 5 An agitator (not shown) that mixes and agitates the taken earth and sand and the injected chemical material, and is provided behind the partition wall 4 in the skin plate 3 and is opposed to the segment 6. A shield jack 7 for generating a propulsive force to advance the rotary cutter 2 together with the skin plate 3 by taking force, and an intake end 8a is positioned in the cutter chamber 5 through the partition wall 4, End portion 8b is the skin plate 3 behind, is extended diagonally upward, and sediment from the ribbon axial without screw conveyor 8 which is earth removal from the cutter chamber within 5. The succeeding carriage 9 behind the shield machine 1 is provided with a cab 10 of the shield machine 1, and the driver controls the operation of the shield machine 1 from the cab 10.

  The mud pressure shield machine 1 according to the present embodiment is particularly suitable when excavating a face Z of a natural ground made of cobbles or cobblestone layers that may contain boulders X that are not preferably taken into the cutter chamber 5. Applies to Of course, the present invention can also be applied to a boulder-mixed cobble, a cobblestone layer, a normal gravel layer or the like that does not contain such a boulder X.

  As shown in FIG. 2, the rotary cutter 2 is a spoke type. The rotary cutter 2 is positioned at the center of the rotary cutter 2, and has a hub portion 12 to which the center bit 11 is attached, and extends radially from the hub portion 12 toward the peripheral edge of the rotary cutter 2. It comprises six spoke portions 16 to which the roller cutter 15 is attached, an intermediate ring 17 that connects the middle portions of the spoke portions 16, and an outer peripheral ring 18 that connects the tip portions of the spoke portions 16.

  The intermediate ring 17 is positioned substantially in the middle between the spoke portion 16 and the spoke portion 16 to restrict the gravel X, cobblestone, etc. having the above-mentioned large outer dimensions from being taken into the cutter chamber 5 from between the spoke portions 16. For this purpose, a restricting projection 19 is provided. That is, a boulder uptake restriction section R is formed in the rotary cutter 2 around the hub portion 12, as defined by a spoke portion 16, an intermediate ring 17 having a restriction projection 19, and an outer peripheral ring 18.

  In the mud pressure shield method according to the present embodiment, the chemical material is added to the earth and sand excavated by the rotary cutter 2 and is agitated and mixed by the agitator to convert the excavated earth and sand into plastic fluid and impermeable mud. . Then, the mud is filled in the cutter chamber 5, the screw conveyor 8, and the discharge pipe 25 described later, and the mud filled in the cutter chamber 5 and the like is pressed by the propelling force of the shield jack 7 to generate mud pressure. The mud pressure counteracts the face pressure and the face Z is stabilized.

  When the mud pressure shield machine 1 is propelled, in order to maintain the stability of the face Z, for example, the rotational speed of the rotary cutter 2 is kept constant, and the extension speed of the shield jack 7 and the rotational speed of the screw conveyor 8 are adjusted. The mud pressure generated in the cutter chamber 5 from the earth discharging pipe 25 through the screw conveyor 8 is measured by a earth pressure gauge (not shown) provided in the partition wall 4 so that the measured mud pressure is always kept constant. And I try to dig.

  The mud pressure shield excavator 1 according to the present embodiment includes a cutter chamber 5 for excavating the face Z of a natural mountain mixed with fine sand, coarse sand, and gravel, cobblestones, and even boulders X. Mud adjustment means for optimizing the state of the mud inside is provided.

  The mud adjustment means is provided at appropriate positions on the spoke portion 16 and the hub portion 12 of the rotary cutter 2, and the first injection means 20 for injecting the chemical material toward the face Z in front of the rotary cutter 2, and the central portion of the partition wall 4. The second injecting means 21 for injecting the chemical material into the cutter chamber 5 and the peripheral position of the partition wall 4 are provided in the vicinity of the outer periphery of the skin plate 3 and into the cutter chamber 5. The third injection means 22 for injecting the drug material is provided.

  The 1st and 3rd injection means 20 and 22 inject mud soil materials, such as a bentonite type additive. The second injection means 21 injects a bubble material. Specific configurations of the injection means 20 and 22 for injecting the mud material and the injection means 21 for injecting the foam material are well known.

  Moreover, although the case where the injection means 20 and 22 which inject | pour a mud clay material and the injection means 21 which inject | pour a foam material are provided separately is shown in this embodiment, a mud clay material and a foam material are injected into an inlet (FIG. The mixing means 20 and 22 for the mud material and the injection means 21 for the foam material are used by mixing in the vicinity or by shifting the injection timing of the mud material and the injection timing of the foam material. You may do it. That is, you may make it inject | pour mud material and a foam material from all the injection | pouring means 20-22.

  Sediment material containing gravel that has just been excavated and crushed by the rotary cutter 2 from the face Z is rotated by the rotary cutter 2 and is poured from the first injection means 20 of the rotary cutter 2 toward the face Z. In addition, it is taken into the cutter chamber 5 while being stirred and mixed with the bubble material. Also, the earth and sand containing gravel that has been excavated from the face Z by the rotary cutter 2 and crushed and taken into the cutter chamber 5 is removed from the second and third injection means 21 and 22 of the partition wall 4 in the cutter chamber 5. It is agitated and mixed with a mud clay material or a foam material injected into the chamber 5.

  That is, the earth and sand containing gravel excavated by the rotary cutter 2 is stirred and mixed with both the mud clay material and the foam material in the face Z position and the cutter chamber 5 before being taken into the screw conveyor 8.

  Further, the mud pressure shield machine 1 according to the present embodiment is provided with blockage monitoring means for monitoring blockage of earth and sand between the cutter chamber 5 and the screw conveyor 8. The blockage tendency of the earth and sand is estimated by the increase in the earth and sand temperature due to the frictional heat accumulated in the earth and sand that is stirred.

  The blockage monitoring means is provided in the screw conveyor 8 and is installed in the cab 10 for measuring the temperature of the earth and sand containing gravel (carrying out temperature) transported by the screw conveyor 8. The control unit 24 includes a control panel 24 that inputs the discharge temperature measured at 23 and displays the discharge temperature for the driver to visually recognize the discharge temperature.

  The soil discharge temperature measured by the temperature sensor 23 is compared with the set temperature for blockage estimation, and is input to the control panel 24 as feedforward control data for preventing blockage. When a tendency of temperature rise toward the set temperature is determined, the amount of chemicals to be injected from the injection means 20 to 22 is increased by manual control by the driver or automatic control by the control panel 24.

  The earth and sand discharge device 30 of the mud pressure shield machine 1 according to the present embodiment includes the ribbon type shaftless screw conveyor 8 and the earth discharge pipe 25 connected to the screw conveyor 8.

  Ribbon-type shaftless screw conveyor 8 is well known in the art. For example, as shown in FIG. 3, a continuous spiral blade is formed along the length of an inner peripheral surface of an inner cylinder 32 serving as a conveyance path 31. 33, the inner cylinder 32 is rotatably supported inside the fixed outer cylinder 34, a ring gear is provided at the longitudinal end of the inner cylinder 32, and a pinion provided on the drive motor is engaged with the ring gear. By rotating the inner cylinder 32 with a drive motor, the excavated earth and sand are conveyed by the spiral blade 33 from the intake end 8a in the cutter chamber 5 toward the discharge end 8b. .

  The conveying path 31 of the screw conveyor 8, that is, the inner cylinder 32, is different from a screw conveyor with a shaft that is easily clogged with gravel or the like, and the maximum conveyable gravel diameter M is at least the radius (D2 / 2) of the conveying path 31. However, it is possible to transport such large gravel that cannot be transported by a screw conveyor with a shaft.

  The size of such gravel is defined by the boulder uptake restriction section R of the rotary cutter 2. The inner diameter of the conveyance path 31 of the screw conveyor 8 is set in relation to the size of the boulder uptake restriction section R so that the boulder taken into the cutter chamber 5 can be conveyed by the screw conveyor 8. Alternatively, the size of the boulder uptake restriction section R is set in relation to the inner diameter of the conveyance path 31.

  As shown in FIGS. 4 and 5, a discharge pipe 25 is connected to the discharge end portion 8 b of the screw conveyor 8, and the discharge pipe 25 extends to a slide carry-out carriage 26 incorporated in the succeeding carriage 9, The soil discharged from the conveyor 8 is discharged to the slide carrying cart 26. The inside of the soil discharge pipe 25 becomes a carry-out path 35 for excavated soil.

  At the connecting portion between the discharge end portion 8a of the screw conveyor 8 and the soil discharge pipe 25, there is a sediment retaining portion 38 formed with an inner diameter larger than the diameter of the discharge path 35 of the soil discharge pipe 25 and the conveyance path 31 of the screw conveyor 8. The earth and sand retaining portion 38 is formed so that the excavated earth and sand sent from the screw conveyor 8 to the earth discharging pipe 25 is temporarily retained and can be smoothly moved while generating earth pressure.

  As shown in FIG. 4, the diameter D <b> 1 of the carry-out path 35, i.e., the inner diameter of the soil discharge pipe 25, can receive and carry boulders discharged from the screw conveyor 8, and cause a pressure loss described later. The diameter is set smaller than the diameter D2 of the transport path 31 (D1 <D2). The excavated earth and sand received in the earth discharge pipe 25 is sent toward the slip-out unloading carriage 26 while flowing in the earth discharge pipe 25 by the pushing action of the excavated earth and sand by the screw conveyor 8.

  The length of the soil removal pipe 25 reaching from the screw conveyor 8 to the slip-out unloading carriage 26 is such that a plug zone (water stoppage area) is formed in the soil removal pipe 25 due to pressure loss of excavated earth and sand sent while flowing in the transport path 35. It is set to be longer than the specified length. The pressure loss is calculated, for example, so as to meet the assumed maximum face soil pressure, and the length of the discharge pipe 25 is set to a length that can secure such a pressure loss. Moreover, a pressure loss can be changed by adjusting the plastic fluidity etc. of excavated earth and sand.

  The pressure loss can be calculated by using a well-known “expression of pressure loss of flow in a pipe in fluid dynamics”. As a matter of course, the pressure loss is reduced when the inner diameter of the earth removal pipe 25 is large, and the pressure loss is increased when the inner diameter of the earth removal pipe 25 is small. Therefore, the length of the earth removal pipe 25 is set in relation to the inner diameter. The

  The pressure loss when the excavated earth and sand moves through the discharge path 35 inside the drainage pipe 25 contributes to the generation of mud pressure inside the drainage pipe 25, and forms a plug zone that becomes a water stop region by this mud pressure, As a result, the discharge of earth and sand caused by groundwater pressure and the like is prevented.

  The earth and sand discharging device 30 of the mud pressure shield excavator according to the present embodiment can receive boulders and has a plug zone formed on the ribbon type shaftless screw conveyor 8 that can smoothly convey even the boulders. It is established by combining the drainage pipe 25 set to the length that causes the pressure loss, so that the excavated sediment including boulders can be discharged smoothly while ensuring the mud pressure against the face pressure. It has become.

  An air supply pipe 36 that supplies air to the transport path 35 is connected to the soil discharge pipe 25 in order to adjust the fluidity of the excavated sediment moving inside. In addition, a water supply pipe 37 for supplying water to the transport path 35 is connected to the soil discharge pipe 25 in order to adjust the fluidity of the excavated earth and sand that moves inside. These water and air, together with mud material, change the plastic fluidity of the excavated earth and sand, and adjust the pressure loss caused inside the earth discharge pipe 25, and consequently the mud pressure against the face soil pressure.

  In particular, when the mud pressure is higher than the face pressure, specifically, when the length of the discharge pipe 25 that causes pressure loss is too long, air and water are mixed into the excavated soil in the discharge pipe 25. Thus, the length of the soil discharge pipe 25 can be apparently adjusted to be set short.

  In the illustrated example, the air supply pipe 36 and the water supply pipe 37 are provided at the end of the soil discharge pipe 25 on the screw conveyor 8 side, and the fluidity of the excavated sediment in the soil discharge pipe 25 is determined in advance at the upstream position of the soil discharge pipe 25. Can be adjusted appropriately. However, the air supply pipe 36 and the water supply pipe 37 may be appropriately set in terms of connection location and number of installations.

  Next, the mud pressure shield machine 1 according to the above embodiment will be exemplified to describe the operation of the sediment discharge device. Specifically, the mud pressure shield excavator earth and sand discharging apparatus according to the present invention has a particle size accumulation curve shown in FIG. 6 (fine particles (sand content) having a particle size of less than 2 mm do not exceed 20%, and the particle size is 2 mm. It was developed for natural ground with over 80% of the above gravel stones (pebbles), and was actually used in tunnel excavation near Dainan Bay in Taiwan in a confidential state.

  The mud pressure shield method basically uses a propelling force of the shield jack 7 after adding chemicals to the mud filled from the cutter chamber 5 to the screw conveyor 8 to ensure plastic fluidity and imperviousness. A mud pressure that antagonizes the face pressure is generated, and the face Z is stably maintained by this mud pressure, and the rotational speed of the screw conveyor 8 that discharges from the cutter chamber 5 and the extension speed of the shield jack 7 are appropriately adjusted. Adjust and proceed with excavation.

  In the excavation work of the mud pressure shield machine 1, the mud pressure shield method according to the present embodiment uses a mud material such as bentonite-based additive and a cellular material as the chemical material, and uses these chemical materials as the first to the first materials. 3. From 3 injection means 20-22, it injects toward the cutting face Z ahead of the rotary cutter 2, and into the cutter chamber 5 again.

  In the present embodiment, it is intended for excavating a face Z of a natural ground made of cobblestone or cobblestone that can contain boulders X that are not preferably taken into the cutter chamber 5, and is represented by a bentonite-based additive. In addition to the action of increasing the plastic fluidity and imperviousness of earth and sand, mud clay materials are used to reduce gravel content such as gravel and cobblestones that crush boulders X. With respect to the excavated earth and sand, the gravel is wrapped with the excavated earth and sand to prevent the gravel from separating from the earth and sand, and the integrity of the earth and gravel is improved. Thereby, it is possible to suppress the separation action such as hindering the adhesion and bonding between the earth and sand particles, which is a difficulty of the foam material.

  In addition, the foam material is used in combination with the above-mentioned mud-soil material. The plastic fluidity and imperviousness that are effective can be suppressed to prevent the sediment containing gravel from adhering to the rotary cutter 2 and the partition wall 4, and by the cushioning action of the foam material that cannot be obtained with the mud material Enhance the compressibility of excavated sediment and mud material, prevent the gravel from rolling and moving in the cutter chamber 5 and screw conveyor 8, and even if it moves, the mud pressure suddenly fluctuates due to its cushioning action Can be suppressed.

  Therefore, by using a mud material and a foam material in combination, the mud pressure can be stabilized and the face Z can be stably maintained, and the gravel drained by the screw conveyor 8 can be stabilized. Smoothing can prevent the occurrence of blockage, and also prevent the occurrence of ejection.

  The excavated soil including the gravel mixed and stirred with the mud material and the foam material in this way is taken into the screw conveyor 8 from the cutter chamber 5, and further discharged through the soil discharge pipe 25 to the waste carrying cart 26. Is done. The ribbon type shaftless screw conveyor 8 is the spiral blade 33 of the inner cylinder 32, takes the excavated earth and sand in the cutter chamber 5 from the intake end 8a, and conveys it toward the discharge end 8b.

  Ribbon type shaftless screw conveyor 8 is different from screwed shaft conveyors in that the maximum transportable gravel diameter M can be set to be equal to or larger than the radius (D2 / 2) of transport path 31 and is made of excavated soil containing boulders. Even if it exists, it can take in from the cutter chamber 5 and can convey smoothly. The excavated earth and sand that has reached the discharge end portion 8b of the screw conveyor 8 is fed into the earth discharging pipe 25 by the pushing action from the screw conveyor 8, and the earth discharging pipe 25 moves the excavated earth and sand toward the slide carrying cart 26 by this pushing action. And carry it out. Air and water are appropriately mixed from the air supply pipe 36 and the water supply pipe 37 into the excavated earth and sand carried out by the soil discharge pipe 25, thereby adjusting the fluidity.

  The drainage pipe 25 is set in advance to be longer than the length at which the plug zone is formed due to the pressure loss of the excavated earth and sand to be carried out. Mud pressure is generated against the earth pressure. As a result, the balance between the mud pressure and the face pressure is maintained, and the amount of propelling by the shield machine 1 and the amount of earth discharged by the earth and sand discharge device 30 are balanced while keeping the face stable. While digging.

  In the operation of the mud earth pressure shield machine 1, the earth pressure value detected by the earth pressure gauge is compared with the set earth pressure value. If the earth pressure value is large, the rotational speed of the screw conveyor 8 is increased. If the earth pressure value returns to the set earth pressure value, the rotational speed of the screw conveyor 8 is restored. When the earth pressure value does not decrease, the excavation speed is reduced. Thereafter, when the earth pressure value returns to the set earth pressure value, the excavation speed is returned.

  On the other hand, when the earth pressure value is small, the rotational speed of the screw conveyor 8 is reduced, and when the earth pressure value returns to the set earth pressure value, the rotational speed of the screw conveyor 8 is returned. When the earth pressure value does not increase, the excavation speed is increased and the operation state is continued. This is because a faster excavation speed is preferable. Of course, if the earth pressure value reaches the set earth pressure value, the operation is continued in the current operation state.

  In the sediment discharge device 30 of the mud pressure shield machine according to the present embodiment, the gravel diameter M that is connected to the cutter chamber 5 and the maximum transportable gravel diameter M is equal to or larger than the radius (D2 / 2) of the transport path 31, Ribbon type shaftless screw conveyor 8 that conveys excavated earth and sand from the cutter chamber 5, and an unloading path that is connected to the screw conveyor 8 and has a diameter D 1 that is smaller than the diameter D 2 of the conveying path 31 of the screw conveyor 8. 35 and a discharge pipe 25 set longer than the length at which the plug zone is formed by the pressure loss of the excavated earth and sand to be carried out, the ribbon type shaftless screw conveyor 8 and the discharge pipe 25 have a large diameter. By the drainage pipe 25 that is capable of appropriately transporting gravel and has a length set so as to form a plug zone due to pressure loss of excavated sediment Supplemented points lack of ribbon axial without screw conveyor 8, it is possible to secure the construction by mud pressure shield tunneling.

  That is, in the ribbon type shaftless screw conveyor 8, the excavated earth and sand cannot be conveyed in a solid state. In particular, in the case of excavated earth and sand including boulders, the boulders push the excavated earth and sand and roll in an unstable manner. Although the pressure in 8 is extremely unstable, the discharge pipe 25 is set to such a length that a plug zone is formed by the pressure loss of the excavated earth and sand transported along the discharge path 35. By forming the zone, mud pressure can be generated in the cutter chamber 5 from the discharge pipe 25 through the screw conveyor 8 so as to maintain equilibrium with the face pressure, and the mud pressure shield construction method should be constructed safely. Can do.

  In addition, the plug zone can appropriately resist the groundwater pressure, and can prevent the occurrence of ejection.

  As described above, in order to make up for the shortcomings of the ribbon type shaftless screw conveyor 8, even if it is a natural mountain where many boulders are scattered by combining the earth removal pipe 25 that forms a plug zone with pressure loss. In general, excavation work can be carried out in the same way as excavation of general gravel layers.

  In addition, since the air supply pipe 36 and the water supply pipe 37 are connected to the soil discharge pipe 25, the fluidity of the excavated soil can be adjusted to control the pressure loss, and blockage or the like occurs in the soil discharge pipe 25. It is possible to appropriately form the plug zone while preventing this.

DESCRIPTION OF SYMBOLS 1 Mud pressure shield machine 2 Rotating cutter 5 Cutter chamber 8 Ribbon-type shaftless screw conveyor 25 Drainage pipe 30 Sediment discharge device 31 Conveyance path of screw conveyor 35 Drainage path of discharge pipe 36 Air supply pipe 37 Water supply pipe Z Cut face

Claims (3)

Mud pressure shield digging that excavates and crushes from the face by a rotary cutter and discharges the excavated soil containing gravel filled in the cutter chamber behind the rotary cutter to the outside while facing the face pressure. In the machine earth and sand discharge device,
Connected to the cutter chamber, the maximum transportable gravel diameter is equal to or greater than the radius of the transport path, and is connected to the screw conveyor with a ribbon type shaftless screw conveyor that transports excavated earth and sand containing gravel from the cutter chamber, A discharge path set to a diameter smaller than the diameter of the conveying path of the screw conveyor, and a discharge pipe set to a length longer than a length at which a plug zone is formed by pressure loss of the excavated earth and sand The mud pressure shield excavator's sediment discharge device.   The mud pressure shield excavator earth and sand according to claim 1, wherein an air supply pipe for supplying air to the carry-out path is connected to the earth discharge pipe in order to adjust fluidity of the excavated earth and sand. Discharging device.   3. The mud pressure shield excavator according to claim 1, wherein a water supply pipe that supplies water to the carry-out path is connected to the soil discharge pipe in order to adjust fluidity of excavated sediment. Sediment discharge device.

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