JP4617909B2 - Injection method of additives in shield method - Google Patents

Description

  The present invention relates to an additive injection method in a shield method, and in particular, controls the injection amount of the additive according to the earth pressure in the chamber of the shield machine, and provides a uniform additive material corresponding to the earth pressure distribution. The present invention relates to a technique that enables injection.

  The shield method is generally adopted as a tunnel construction method for ground where there is groundwater or soft ground, for example, in civil engineering, etc. The body is formed, and the excavation work is performed by the shield machine while obtaining the propulsion reaction force from the formed lining body.

  This shield machine cuts the face of the ground excavated soil facing the cutter spoke while rotating the cutter spoke on which many cutter bits are erected, and takes the excavated soil into the chamber behind the cutter spoke. Furthermore, it advances while being conveyed and discharged backward by a screw conveyor provided at the lower part of the chamber.

  Here, in such earth pressure type shield method, for the purpose of stabilizing the face, improving the water stoppage and fluidity of the excavated soil, and suppressing the fluctuation of the face pressure, air bubbles and the like are introduced from the inlet provided in the cutter spoke. Injecting additives such as bentonite and clay into the face and the chamber is performed. That is, a plurality of additive inlets arranged in a straight line in the radial direction along the cutter spoke are provided, and a predetermined amount of additive that is set according to the amount of soil discharged and the state of soil discharge is set in the chamber. Is controlled based on a detected earth pressure detected by a pressure sensor attached to a substantially central position of the bulkhead of the bulkhead that forms the partition, and the injection is performed from the injection port.

Further, the pressure in the chamber is detected by a plurality of pressure sensors to determine the pressure gradient, and the addition rate of the additive is adjusted to the chamber according to the difference between the pressure gradient and the estimated natural pressure gradient. The following patent document describes a technique for injecting from the inlet provided in the center of the bulkhead and adjusting the discharge amount according to the difference between the chamber pressure and the estimated ground pressure, and excavating the earth and sand in the chamber. 1 is known.
Japanese Patent No. 2700411

By the way, even if the shield machine is of a medium size, its diameter is about 5 m, and when it is large, its diameter exceeds 10 m. Therefore, even in a medium-sized shield machine, the earth pressure difference between the upper end and the lower end in the chamber is considerable. For this reason, when the additive material injection amount from the injection port is set to be the same at the upper end portion and the lower end portion in the chamber, on the lower end side where the earth pressure is high, the injection resistance is large and it seems to be insufficient. Since the injection resistance is small on the upper end side where the earth pressure is low, it becomes excessive, and there is a problem that it is difficult to uniformly inject the additive into the chamber. In addition, the problem becomes more conspicuous in a configuration in which an additive is injected from an injection port provided in the center of the chamber as shown in Patent Document 1.

  If the amount of the additive material injected into the chamber becomes uneven, the plastic fluidity of the excavated earth and sand deteriorates, and adhesion of earth and sand to the chamber and cutter spoke may occur, which may cause clogging. There is.

  In particular, in the case of a large shield machine having a large cross section with a diameter exceeding 10 m, the earth pressure difference between the upper end and the lower end in the chamber becomes as large as 0.1 MPa, so the above problem Will be more serious.

  This invention is made | formed in view of the said situation, The objective is to provide the additive injection method in the shield construction method in which the injection | pouring of the uniform additive corresponding to earth pressure distribution is possible.

  In order to achieve the above object, according to the first aspect of the present invention, the earth pressure in the chamber of the shield machine is detected by a pressure sensor, and the additive material provided on the cutter spoke is based on the detected earth pressure. When adjusting the amount of additive material injected from the inlet, a plurality of the pressure sensors are arranged in at least two locations near the upper end and the center of the chamber, and the position of the additive material inlet is determined from the rotation angle of the cutter spoke. Calculating, selecting a pressure sensor close to the inlet from the plurality of pressure sensors according to the position of the inlet, and determining from the inlet based on the detected earth pressure of the selected pressure sensor It is characterized by adjusting the amount of additive material injected.

  Here, as shown in claim 2, the inside of the chamber is divided into an upper control region, an intermediate control region, and a lower control region that are symmetrical in the circumferential direction, and the intermediate control region and the lower control region. A plurality of pressure sensors are arranged symmetrically with respect to each region, and when the additive inlet is in the upper region, the output value from the pressure sensor provided near the upper end of the chamber is controlled by the control earth pressure. In the middle area and the lower control area, the output value of the pressure sensor having the smallest detected earth pressure among the plurality of pressure sensors in each area is used as the control earth pressure. obtain.

  According to the additive injecting method in the shield method of the present invention as described above, uniform air bubbles corresponding to the earth pressure distribution can be injected into the cross section. For this reason, even with a large cross section, the bearing effect and the plastic fluidity can be improved, and the cutter torque can be reduced and the blockage can be prevented.

  Hereinafter, a preferred embodiment of an additive injection method in the shield method according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a schematic sectional side view showing an example of a shield machine used in the earth pressure shield method. As shown in the figure, the shield machine 2 rotates a cutter spoke 6 on which a large number of cutter bits 4 are erected, and cuts the face of the soil to be excavated in the natural ground facing the cutter spoke 6. The soil is taken into the chamber 7 behind the cutter spoke 6 and further advanced while being transported and discharged rearward by the screw conveyor 8, and is extended in a state where the jack for propulsion 10 is in contact with the reaction force receiver. It is designed to gain a forward force. For this reaction force reception, the lining body 12 is used to cover the inner peripheral surface of the tunnel T formed behind the shield machine 2 and is sequentially assembled by the segments 12a.

  Then, during the excavation, for the purpose of stabilizing the face, improving the water stoppage and fluidity of the excavated soil, and suppressing the fluctuation of the face pressure, the additive material inlet 14 provided in the cutter spoke 6 is directed to the face. Additives are injected. In the embodiment, bubbles are used as the additive. The bubbles are formed by mixing and foaming air in the foaming material, and the foaming material is supplied from the foaming material generation plant 16 installed on the ground into the tunnel T behind the shield machine 2 through the shaft 18. .

  In the tunnel T, the foam material mine storage tank 20 for storing the foam material sent from the ground, the foam material injection pump 22 for pumping the foam material in the storage tank 20, and the foam material From the compressor 24 that pumps the air to be mixed, the injection unit 26 that adjusts the injection amount of the foaming material and the mixing amount of the air, the bubble injection control device 28 that controls the operation of the injection unit 26, and the foaming device 30 A bubble material injection means 31 is provided. The foaming material and air metered by the injection unit 26 are sent to a foaming device 30 provided behind the bulkhead 7a in the shield machine 2 through independent lines, and then foamed. A foam material foamed toward the face is injected from an inlet 14 provided in the spoke 6. The compressor 24 and the bubble injection control device 28 are controlled by a command signal from the central control device.

  2 is a front view showing the front end face of the shield machine 2, FIG. 3 is a sectional view taken along the line III-III in FIG. 2, and FIG. 4 is a view taken along the line IV-IV in FIG. It is sectional drawing. As shown in detail in FIG. 2, in this embodiment, the cutter spokes 6 are located between the main cutter spokes 6a extending radially from the center at radial intervals of 60 degrees, and between these main cutter spokes 6a. The sub-cutter spokes 6b having a length of about a half of the radius provided radially on the outer peripheral side in the radial direction. These cutter spokes 6 are sequentially No. 1 in the counterclockwise direction from the 12 o'clock direction shown in the figure. 1-No. When the numbers up to 12 are assigned, the number of the foam material inlet 14 is one at the center of rotation (14-1). 1 in 3 spokes (14-2), no. Two in 7 spokes (14-3, 14-4), no. A total of five ones (14-5) are provided for 11 spokes, and these inlets 14 (1 to 6) have different distances from the center of the machine.

  As shown in FIG. 4, nine pressure sensors 32 are arranged on the bulkhead 7a that defines the back surface of the chamber. These pressure sensors 32 are composed of three replaceable pressure sensors 32a (1 to 3) which can be replaced and six fixed pressure sensors 32b (1 to 6) which cannot be replaced. That is, the interchangeable pressure sensor 32a is located on the vertical axis passing through the center of the machine, one on the upper end side (32a-1), and on the horizontal axis is positioned closer to the outer side in the radial direction and left and right. One (32a-2, 32a-3) is arranged. Further, four fixed pressure sensors 32b (32b-1, 32b-2, 32b) are arranged on the outer side in the radial direction at positions rotated 50 degrees left and right from the upper end and the lower end with respect to the vertical axis passing through the center of the machine. -3, 32b-4), two on the left and right (32b-5, 32b-6) are located on the horizontal axis passing through the center of the machine at a position about 1/3 of the radius. . In the drawing, the phantom line with 14 (1 to 6) is the position of the injection port shown in FIG.

FIG. 5 is a block diagram schematically showing the bubble material injection means 31 connected to each of the five injection ports 14 (1 to 5) and its control system. As shown in the figure, the bubble injection control device 28 of each bubble material injection means 31 controls the rotation speed of the foaming material injection pump 22 and the air valve opening degree of the injection unit 26 to control the foaming material. The flow rate and the air flow rate are adjusted, and the adjustment amount is calculated based on a command signal from the central controller 40. That is, the central controller 40 sets the foaming ratio and the injection rate of the foam material according to the excavation speed and earth pressure of the shield machine 2, and calculates the air flow rate and the foaming material flow rate based on the set values. Then, the calculated value is sent to the bubble injection control device 28 as a command signal. The bubble flow rate, the air flow rate, and the foaming material flow rate are generally calculated as follows.
Bubble flow rate = cross-sectional area × (excavation speed / 1000) × (injection rate / 100) × 1000
Air flow rate = Bubble flow rate × (foaming magnification-1) / foaming magnification × (1 + control earth pressure × 10)
Foaming material flow rate = bubble flow rate / firing magnification

  By the way, the central controller 40 changes the control earth pressure depending on the position of each inlet when calculating the bubble flow rate from each inlet and the air flow rate and the foaming material flow rate for the bubble flow rate. ing. That is, the central controller 40 calculates the position of each additive inlet 14 (14-1 to 14-5) from the rotation angle of the cutter spoke 6, and each of the inlets 14 (14-1 to 14-5) is calculated. Pressure sensor 32 (32a-1 to 32a-3, 32b-1 to 32b-6) close to each inlet 14 (14-1 to 14-5) is selected from a plurality of pressure sensors according to the position. Then, based on the detected earth pressure of the selected pressure sensor 14, the amount of additive material injected from each inlet 14 (14-1 to 14-5) is calculated, and the calculated value is connected to each inlet. Is transmitted as a command signal to the bubble injection control device 28 of the bubble material injection means 31, and the bubble injection control device 28 controls the number of rotations of the foaming material injection pump 22 according to the calculated value, and the injection unit 26. The foaming material flow rate and the air flow rate are adjusted by controlling the air valve opening degree.

  That is, in the present embodiment, as shown in FIG. 4, a range of ± 50 degrees in the circumferential direction from the upper end position (12 o'clock position) is set as the upper control region with respect to the vertical line passing through the machine center, and the lower end position ( A range of ± 50 degrees in the circumferential direction from the 6 o'clock position is defined as a lower control region, and a range sandwiched between these upper control region and lower control region is defined as an intermediate control region. When the cutter spoke (No. 3, No. 7, No. 11) 6a provided with the inlet 14 (14-2 to 14-5) enters the upper control region, it is provided in the cutter spoke. The control earth pressure of the injection port 14 (14-2 to 14-5) is selected and adopted from the output value from the pressure sensor 32a-1 provided at the upper end of the bulkhead 7a. Further, in the lower region, the lower one of the output values from the pressure sensor 32b-3 or 32B-4 is adopted as the control earth pressure. Further, when the left and right intermediate control regions are entered, the output value from the pressure sensor 32a-2 or 32a-3 closer to the outer periphery is adopted as the control earth pressure.

  That is, the inside of the chamber 7 is divided into an upper control area, an intermediate control area, and a lower control area that are symmetrical in the circumferential direction, and the intermediate control area and the lower control area have a plurality of left and right symmetry. Pressure sensors 32a-2, 32a-3, 32b-1, 32b-2, 32b-3, and 32b-4 are arranged.

  Here, when the additive inlet 14 is in the upper region, the output value from the pressure sensor 32a-1 provided in the vicinity of the upper end in the chamber 7 is used as the control earth pressure, and the intermediate region and lower control are performed. When in the area, the pressure with the lowest detected earth pressure among the plurality of pressure sensors 32a-2, 32a-3, 32b-1, 32b-2, 32b-3, 32b-4 in each area. The output value of the sensor may be used as the control earth pressure. Further, the output values of a plurality of sensors installed in each region may be averaged and used as the control earth pressure.

  Or according to each rotation angle of the cutter spoke (No. 3, No. 7, No. 11) 6a provided with the inlet 14 (14-2 to 14-5), the cutter spoke (No. 3, No. 7, No. 11) The output value from the pressure sensor closest to each inlet 14 (14-2 to 14-5) provided in 6a is used as the control soil of each inlet. You may make it employ | adopt as pressure.

  The four fixed pressure sensors 32b-1, 32b-2, 32b-5, and 32b-6 are not used, but these are used for backup at the time of failure and more appropriate control according to the situation. At this time, it is used by switching appropriately.

It is side sectional drawing which shows schematic structure of the shield machine used for the earth pressure type shield method to which this invention is applied. FIG. 2 is a front view showing the front end face of the shield machine 2. It is sectional drawing of the III-III arrow line part in FIG. It is sectional drawing of the IV-IV arrow line part in FIG. It is a block diagram which shows a bubble material injection | pouring means and its control system roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Shield machine 6 Cutter spoke 7 Chamber 8 Screw conveyor 10 Propulsion jack 12 Covering body 14 Bubble injection port 16 Foaming material production plant 20 Foaming material underground storage tank 22 Injection pump 24 Compressor 26 Injection unit 28 Bubble injection control device 31 Bubble material injection means 32 Pressure sensor

Claims (2)

When detecting the earth pressure in the chamber of the shield machine with a pressure sensor, and adjusting the additive injection amount from the additive inlet provided on the cutter spoke based on the detected earth pressure,
A plurality of the pressure sensors are arranged in at least two locations near the upper end portion and near the central portion of the chamber, and the position of the additive inlet is calculated from the rotation angle of the cutter spoke, and the position is determined according to the position of the inlet. Selecting a pressure sensor close to the inlet from a plurality of the pressure sensors, and adjusting an additive material injection amount from the inlet based on a detected earth pressure of the selected pressure sensor. The injection method of the additive in the shield method. The inside of the chamber is divided into an upper control region, an intermediate control region, and a lower control region that are symmetrical in the circumferential direction, and a plurality of pressures are symmetrically applied to the intermediate control region and the lower control region. When the sensor is disposed and the additive inlet is in the upper region, the output value from the pressure sensor provided near the upper end of the chamber is used as the control earth pressure, and the control in the middle region and the lower control is performed. 2. The addition in the shield method according to claim 1, wherein when it is within the area, the output value of the pressure sensor having the smallest detected earth pressure among the plurality of pressure sensors in each area is set as the control earth pressure. Material injection method.

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